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LXXI International conference "NUCLEUS – 2021. Nuclear physics and elementary particle physics. Nuclear physics technologies"
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Europe/Moscow
Description
The LXXI International conference "NUCLEUS – 2021. Nuclear physics and elementary particle physics. Nuclear physics technologies" will be held in St. Petersburg from September 20 to 25, 2021. The conference format is on-line only.
The conference is devoted to the actual nuclear and high energy physics problems, nuclear medicine. Also the synchrotron and neutron radiation studies will be covered. This is the oldest international nuclear conference in Russia and also one of the oldest in the World (since 1950). The main conference program will cover a rather broad range of topics.
The aim of the conference is the discussion of the latest results on:
- Experimental and theoretical studies of the properties of atomic nuclei.
- Experimental and theoretical studies of nuclear reactions.
- Modern nuclear physics methods and technologies.
- Relativistic nuclear physics, elementary particle physics and high-energy physics.
- Neutrino physics and astrophysics.
- Plasma physics and thermonuclear fusion.
- Synchrotron and neutron studies and infrastructure for their implementation.
- Nuclear medicine.
- Nuclear-physical methods in the study of cultural heritage objects.
The program will include plenary (30+5 min), oral (20+5 min) and poster presentations.
The working language of the Conference is Russian and English.
Organizing institutes
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Partners
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Nucleus2021
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Plenary
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1
Conference openingSpeaker: A.V. Titov (SPbU), V.V. Voronin (NRC "Kurchatov Institute"), V.A. Matveev (JINR), P. Giubellino (GSI), L. Musa (CERN), V.I. Zherebchevsky (SPbU)
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3
Reactor PIK status and scientific program for elementary particle and nuclear physicsSpeaker: Vladimir Voronin (Petersburg Nuclear Physics Institute NRC "Kurchatov Institute")
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10:25 AM
Coffee break
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4
Current status of the MPD@NICA Project
The Multi-Purpose Detector (MPD) is currently under construction in JINR, Dubna as part of the NICA Accelerator Complex. The MPD is designed to study the properties of the strongly interacting matter in the regime of maximum baryonic density expected to be reached in heavy-ion collisions at the center of mass energy of 4-11 GeV. The detector will operate in the collider mode and is equipped to measure various hadronic, leptonic and photonic signatures of the phase transition and critical point in a wide and uniform acceptance and dynamic range. In this talk, we review the current status of the MPD construction and the physical potential of the apparatus in the first years of its operation.
Speaker: Viktor Riabov (NRC Kurchatov Institute PNPI (RU)) -
5
Physics with SPD experiment at NICA collider
A brief overview of the Spin Physics Detector (SPD) experiment is presented.
SPD is a future multipurpose experiment foreseen to run at the NICA collider, which is currently under construction at the Joint Institute for Nuclear Research (JINR, Dubna, Russia).
The physics program of the experiment is based on collisions of longitudinally and transversely polarized protons and deuterons at c.m.s. NN energy up to 27 GeV and luminosity up to $10^{32}\text{cm}^{−2}\text{s}^{−1}.$
SPD will operate as a universal facility for the comprehensive study of the unpolarized and polarized gluon content of the nucleon, using complementary probes such as: charmonia, open-charm, and prompt-photon production processes.
Possible SPD studies at the first stage of the NICA collider operation with unpolarized proton and deuteron beams are also discussed.Speaker: Victor Kim (Petersburg Nuclear Physics Institute - PNPI NRC KI, Gatchina & SPbPU, St. Petersburg) -
6
FAIR and GSI: status and prospectsSpeaker: Paolo Giubellino (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))
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1
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12:35 PM
Lunch break
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Section 1. Experimental and theoretical studies of the properties of atomic nucleiConvener: Egor Zemlin (Saint Petersburg State University, Russia)
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7
Search for cluster states in $^{13}$C
$^{13}$C is a good example of a “normal” nucleus that is well described in the framework of the shell model. Its level scheme is reliably determined up to excitation energies ~ 10 MeV. However, not so long ago, in the framework of the development of the theory of the α-condensation in light nuclei (αBEC), the existence of exotic cluster states in light nuclei with a significantly increased, by 40-70%, size was announced. One of the most likely candidates was the Hoyle state (0$^+_2$, E = 7.65 MeV) in $^{12}$C. It was expected that analogues of the Hoyle state would appear in some neighboring nuclei, for example, the 1/2$^-$ (E = 8.86 MeV) state of $^{13}$C. This was successfully shown by the the Modified Diffraction Model (MDM) method, but obtained radius was much smaller than that predicted by the αBEC theory.
However, some open questions remain regarding the structure of low-lying $^{13}$C states. This leads to increased attention to $^{13}$C so far.
In 2014, our group announced the discovery of a state of $^{13}$C with an abnormally small radius. In the framework of the MDM method, when analyzing data on α-scattering on $^{13}$C at energies of 65 and 90 MeV, it was shown that this state has a radius reduced by 10%. At the same time, in the works of theoreticians dilute structure and increased radius were predicted for this state, and in part of the works, assumptions were made about the rotational structure of this state and the possibility of the formation of a rotational band on it.
Another important question is the search for possible analogues of the Hoyle state in $^{13}$C in highly excited states. At present confirmed analog of the Hoyle state is 1/2$^-$ (8.86 MeV) state in $^{13}$C. Other possible candidate is the state 1/2$^–$ 11.08 MeV. Increased radius close to the radius of the state of 8.86 MeV $^{13}$C was obtained within MDM method analysis. However, this result was obtained only at one energy, on the applicability boundary of the MDM method.
Moreover, the presence of a rotational band based on the Hoyle state in $^{12}$C was confirmed. A reasonable question arises about the existence of rotational bands on analogues of the Hoyle state in $^{13}$C. In [1] a hypothesis was put forward about a new type of symmetry in the $^{13}$C structure - D’$_{3h}$ symmetry. Earlier in the work of the same team of authors, a similar type of D$_{3h}$ symmetry was predicted for the $^{12}$C nucleus. On the basis of D’$_{3h}$ symmetry, the rotational nature of a whole group of low-lying $^{13}$C states was predicted. If this hypothesis is confirmed, our understanding about the $^{13}$C structure will radically change. In the work, 6 rotational bands were proposed, that is, almost all low-lying $^{13}$C states were distributed among the rotational bands.
Thus, a critical analysis of the available data is required to answer the question about the nature of low-lying excited $^{13}$C states.- R. Bijker, Phys. Rev. Lett. 122, 162501 (2019)
Speaker: Andrey Danilov (NRC Kurchatov Institute) -
8
Binding energies of light hypernuclei
Light hypernuclei are a natural laboratory for studying $YN$ and $YY$ interactions [1]. The repulsive nature of the $\Lambda N$ interaction leads to the fact that bound states in light nuclei are generated due to the $N-Y-N$ interaction. The decisive role in this interaction is played by the $\Lambda N\to \Sigma N$ conversion of one type of hyperons into another. Experimental data on hyperon separation energies $B_{\Lambda}[^4_{\Lambda}\text{He}(0^+)]$-$B_{\Lambda}[^4_{\Lambda}\text{H}(0^+)]$=$+0.35$ MeV from ground states of $^4_{\Lambda}$He, $^4_{\Lambda}$H hypernuclei also shows the charge dependence of $YN$ interactions [2]. In this work, the binding energies of light hypernuclei are obtained by solving the homogeneous Faddeev and Faddeev-Yakubovsky intergral equations for 3 and 4 particles in phase space with model $YN$ and realistic $NN$ interactions. The main attention is paid to the comparison of the counting tactic based on the partial-wave expansion [3] of the matrix elements of the transition operators with given separable potentials, and counting tactic [4] that allows direct integration of the matrix elements in a few-body phase space with given local potentials. The procedure [4] for searching T-matrix for three-bodies of different masses without partial-wave expansion is generalized. Direct calculations have confirmed a good agreement between the two methods for calculations the hyperon separation energies in the lightest hypernuclei. The influence of higher partial waves of realistic separable potentials, its charge dependence, and the accuracy of the procedure for solving the Lippman-Schwinger equation by the Noyes-Kowalski method for given local potentials are also discussed.
[1] A. Gal et al., Rev. of Mod. Phys. 88, 035004 (2016).
[2] E. Hiyama et al., Phys. Rev. C 65, 011301 (2001).
[3] M. Egorov et al., Nucl. Phys. A 1009, 122172 (2021).
[4] H. Liu et al., Phys. Rev. C 72, 054003 (2005).Speaker: Mikhail Egorov (RFNC-VNIITF) -
9
Study of neutron decay channels of light neutron-excess nuclei using ab initio methods
In recent decades, research related to low-energy nuclear physics has shown two basic trends. In experimental research, there has been a rapid transition from the study of stable and long-lived nuclei to the study of exotic, including nucleon-unstable systems. In theoretical research, an increasing place is occupied by high-precision microscopic approaches, in particular ab initio (from first principles) methods of describing nuclear systems.
The energy levels of light exotic nuclei are the subject of a large number of the investigation of such a type. Usually ab initio approaches are based on the use of NCSM model together with realistic nucleon-nucleon potentials. The problem of ab initio studies of nucleon- or cluster-decay properties of the states of nuclei looks more complicated. A number of methods to solve it are presented in literature [1-3] but they all have rather narrow ranges of applicability.
Being motivated by that we developed [4-7] a new theoretical scheme adopted for investigating of the decay properties of light nuclei and successfully applied it for the study of the energy levels and decay properties of 7Li and 8Be nuclei. A rather good description of the experimental data was achieved. The properties of a number of states which have not been observed were predicted.
In the present talk an advanced version of the method and the results of study of the spectra and neutron decay channels characteristics of unstable neutron-excess nuclei 7He and 10Li are presented. The predictions have been made may serve as a theoretical support of modern experiments which are performed at FLNR JINR.- Quaglioni S., and Navratil P.// Phys. Rev. C 79 (2009) 044606.
- Shirokov A. M., et al. // J. Phys. Conf. Ser. 2012. Vol. 403. P. 012021.
- Neff T. Phys. Rev. Lett. 106 (2011) 042502.
- Rodkin D. M., Tchuvil’sky Yu. M.// JETP Letters. 2019. V. 109. № 7 P. 425.
- Rodkin D. M., Tchuvil’sky Yu. M.// Physics Letters B. 2019. V. 788 P. 238.
- D. M. Rodkin, Yu. M. Tchuvil'sky // 2020 Chinese Phys. C 44 124105.
- D. M. Rodkin, Yu. M. Tchuvil'sky // Phys. Rev. C 103, 024304.
Speaker: Dr Dmitry Rodkin (Dukhov Automatics Research Institute (VNIIA)) -
10
Thermal shift of atomic levels in hydrogen: influence on the determination of the proton radius
The Quantum Electrodynamics theory for bound states at finite temperatures is discussed. The details of theory can be found in [1] where the derivation of thermal photon propagator in different forms and gauges is presented. The constructed theory is used to find the "thermal Coulomb interaction" and its asymptotic at large distances. Finally, the thermal effects of the lowest order in the fine structure constant and temperature are discussed in detail. Such effects are represented by the thermal one-photon exchange between a bound electron and the nucleus, thermal one-loop self-energy, thermal vacuum polarization, and recoil corrections and that for the finite size of the nucleus. As a result, the influence of thermal effects on the finding the proton radius and Rydberg constant from the hydrogen spectroscopy experiments is discussed.
References:
[1] D. Solovyev, Ann. Phys. 415, 168128 (2020)Speaker: Dmitry Solovyev (Saint-Petersburg State University) -
3:15 PM
Coffee break
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11
Large-scale calculation of nuclear ground-state properties
Presently, the nuclear energy density functional theory is known as the most convenient and powerful theoretical tool for the calculation of the properties of nuclei throughout the nuclear chart. In this work, large-scale calculations are performed using the self-consistent Hartree-Fock-Bogoliubov method [1-2] for even-even nuclei between $8\leq Z\leq 114$. The Skyrme-type functionals are used in the particle-hole channel of the calculations, and zero-range density-dependent pairing force of the surface, mixed, and volume type are employed in the particle-particle channel. Binding energies, two-particle separation energies, charge radii, deformation, and neutron skin thickness properties of nuclei are studied and compared with the available experimental data. The impact of the usage of the different types of pairing forces on the properties of nuclei and location of the particle drip lines are also studied.
- M. Stoitsov et al., Comput. Phys. Commun. 184, 6 (2013).
- R.N. Perez et al., Comput. Phys. Commun. 220 (2017).
*This work was supported by Yildiz Technical University Scientific Research Projects Coordination Unit. Project Number: FAP-2021-4103.
Speaker: Dr Esra Yüksel (Yildiz Technical University) -
12
SELF-CONSISTENT CALCULATIONS OF THE GROUND STATE AND β–DECAY PROPERTIES IN C, N, O REGION.
I.N. Borzov 1,2
1 National Research Centre “Kurchatov Institute”, 123182, Moscow, Russia
2Bogolubov Laboratory of Theoretical Physics, Joint Institute of Nuclear Research, 141980,
†E-mail: Borzov_IN@nrcki.ru, cc: ibor48@mail.ruIncluding the light neutron-rich nuclei to the r-process network is known to change the resulting heavy element abundances [1]. However, large-scale predictions of input data, in particular the β–decay rates are usualy obtained in the HF+BCS Quasiparticle Random Phase (QRPA) approximations. In case of the light neutron-rich nuclei they have to be taken with some care. In loosely bound isotopes close to the particle continuum in which a weak pairing approximation does not work, the cluster effects dominate [2].
The applicability limit of self-consistent description of the beta-decay properties using iterative HF+BCS for the ground state and continuum pnQRPA [3] is carefully checked for very neutron-rich C, N, O nuclei around the neutron shells at N=8,16 and compared with relativistic RHB+RQRPA [4] and FRDM+RPA [5] frameworks.
Supported by the grant of Russian Scientific Foundation (RSF 21-12-00061).Fig. 1. The Sxn-values within the DF3a functional and FRDM in 22-30Oisotopes.
Fig. 2. The T1/2 and total Pn-values calculated from DF3a+CQRPA and RHB+RQRPA
in O isotopic chain compared with AME-2020.- Terasawa, M., K. Sumiyoshi, T. Kajino, G. J. Mathews, and I.Tanihata, Astrophys. J. 562, 479 (2001).
- J. Okolowicz, M. Ploszajczac, W. Nazarewicz, Prog.Theor. Phys.Sup.,196, 230,2012
- I. N. Borzov ,Phys.Rev. C67, 025802 (2003); Phys.At. Nuclei 83, 700(2020)
- T. Marketin, L. Huther, and G. Martı´nez-Pinedo, Phys. Rev. C 93, 025805 (2016).
- P. Mo¨ ller, M. R. Mumpower, T. Kawano, and W. D. Myers, At. Data Nucl. Data Tables 125, 1(2019).
Speaker: Ivan Borzov (NRC KI) -
13
Stability of Light Exotic Λ-hypernuclei with Unstable Cores
In strangeness nuclear physics, exotic hypernuclei with a proton or neutron excess are of particular interest now [1]. Such systems loosely studied experimentally so far can be produced in heavy ion collisions [2] at NICA complex developed at JINR. Properties of exotic hypernuclei can bring new knowledge on subtle features of the hyperon-nucleon and hyperon-nucleus interactions. Specifically, density dependence of the ΛN interaction, ability of the hyperon to distort the nuclear core, charge symmetry breaking ΛN interaction can be investigated [3].
Due to the glue-like role of the Λ hyperon, there is a chance to stabilize systems with unstable nuclear cores. Particularly, we test the possibility of the 9ΛC hypernucleus to be bound. We use the Skyrme-Hartree-Fock approach, which has been widely and successfully applied to Λ hypernuclei including the light ones (e.g., [4,5]) and carefully examine various Skyrme potentials known from the literature. We predict that $^9_Λ\!$C with extreme Z/N=3 (impossible in nonstrange nuclei) is bound. We study also the stability of exotic boron, nitrogen and oxygen hyperisotopes.
References:
1. A. Gal, D.J. Millener, Phys. Lett. B 725, 445-450 (2013).
2. C. Rappold, J. Lopez-Fidalgo, Phys. Rev. C 94, 044616 (2016).
3. T.Yu. Tretyakova, D.E. Lanksoy, Eur. Phys. J. A 5, 391-398 (1999).
4. D.E. Lanskoy, Y. Yamamoto, Phys. Rev. C 55, 5, 2330-2339 (1997).
5. H.-J. Schulze, E. Hiyama, Phys. Rev. C 90, 047301 (2014).Speaker: Semyon Sidorov (Lomonosov Moscow State University) -
14
SPECTROSCOPY OF HEAVY HELIUM ISOTOPE 9He IN REACTIONS OF STOPPED PION ABSORPTION
The unbound heavy helium isotope 9He has one of the largest neutron-to-proton ratios. In spite of a significant number of experimental and theoretical works, the problem of the spectroscopy of 9He remains open [1, 2]. Even for the ground state, there is uncertainty in determining the resonance energy and spin-parity (1- or 1+). The situation with the excited states of 9He is also uncertain. The results obtained in different studies differ more strongly than the given measurement errors. One of the reasons for this discrepancy is poor statistics. Highly excited (Ex ~ 7 MeV) states were observed only in two works [3, 4]. In this work, the study of 9He spectroscopy is carried out on the basis of a joint analysis of the results obtained in three absorption reactions of stopped pions: 11B(π-,pp)X, 14C(π-, p4He)Х and 14C(π-, d3He)Х. The experiment was taken at low energy pion channel of LANL with two-arm multilayer semiconductor spectrometer. In these measurements missing mass resolution was 1 MeV for 11B target and 3 MeV for 14C target.
The advantages of using this method are the ability to study a wide range of excitation energies (up to 30 MeV) with sufficiently high statistics, which was previously demonstrated by us for 6-8He isotopes [5-7]. Reaction (π-,pp) has a pronounced selectivity: the yield of the ground state of the residue is strongly suppressed [7].
s-wave resonance in 9He just above threshold is not observed in all three reactions. The position of the lowest-lying state (Er =1.3(3) MeV) is consistent with the results of most other measurements [1, 2]. For the first time highly excited states are observed in following reactions: 11B(π-,pp)X (Er =10.5(2) MeV and G = 1.5(5) MeV) and 14C(π-, p4He)Х (Ex ~ 12.5 MeV and G ~1.5 MeV).- I.Tanihata, H.Savajols, and R. Kanungo, Progr. Part. Nucl. Phys. 8, 215 (2013).
- H.T.Fortune, EPJA. 54, 51 (2018).
- K.K.Seth et al., Phys. Rev. Lett. 58, 1930 (1987).
- W.von Oertzen et al., Nucl. Phys. A. 588, 129c (1995).
- Yu.B.Gurov et al., Phys. Atom. Nucl. 83, 377 (2020).
- B.A.Chernyshev et al., J. Physics: Conf. Ser. 1690, P.0120030 (2020).
- B.A.Chernyshev et al., JETP Letters. 113, 135 (2021).
Speaker: Dr Борис Чернышев -
5:15 PM
End of session
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7
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Section 2. Experimental and theoretical studies of nuclear reactionsConvener: Nikita Prokofyev (Saint Petersburg State University, Russia)
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1:35 PM
Beginning of the session
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15
Time-dependent description of reactions with weakly bound nuclei $^{11}$Li, $^{11}$Be
Numerical solution of the time-dependent Schrödinger equation [1-3] is used for studying the dynamics of breakup reaction and nucleon transfer at energies above the Coulomb barrier. The spin-orbit interaction is taken into account [2]. The evolution of the wave functions for an outer weakly bound two neutrons of $^{11}$Li nucleus and one neutron of $^{11}$Be in collisions with $^{28}$Si and $^{48}$Ti [3] nuclei is studied (see Fig. 1). The cross sections for the stripping of the outer nucleon due to transfer and breakup are calculated.
Referances
1. A.K. Azhibekov et al., Chinese Journal of Physics 65, 292 (2020).
2. V.V. Samarin, Bull. Russ. Acad. Sci.: Phys. 83, 411 (2020).
3. V. Lima et al., Nucl. Phys. A 795, 1 (2007).Speaker: Viacheslav Samarin (Joint Institute for Nuclear Research) -
16
REACTION CROSS SECTIONS FOR 10,11,12Be BEAM IONS ON 28Si, 59Co, 181Ta TARGETS
Total reaction cross section (σR) values for interaction 10,11,12Be cocktail beam particles with 28Si, 59Co, 181Ta target nuclei in the energy range
12–48 A·MeV are presented. Experimental method of direct measuring of σR is based on detection of prompt n, γ radiation by 12 CsI(Tl) detectors γ-spectrometer [1] was used. A comparison of the two methods for calculating the total cross sections of reactions will be presented. The first technique involves the use of averaged multiplicity. The second technique takes into account the experimental values of the registration efficiency of gamma radiation for various multiplicity of the spectrometer detectors [2].- Yu.E. Penionzhkevich, Yu.G. Sobolev, V.V. Samarin, M.A. Naumenko, Phys. Rev. C 99, 014609 (2019);
- Yu. G. Sobolev et al., Bull. Russ. Acad. Sci.: Phys., 2020, V. 84, No. 8, p. 948 (2020).
Speaker: Mr Sergey Stukalov (JINR) -
17
Microscopic analysis of elastic scattering of one-proton halo nucleus $^{17}$F on different mass targets
An analysis of cross sections of elastic scattering of $^{17}$F on
$^{12}$C, $^{14}$N, $^{58}$Ni, and $^{208}$Pb nuclei at energy 170
MeV and on $^{208}$Pb at various energies is carried out by using
the microscopic optical potentials (OPs). The proton and neutron
density distributions of the exotic nucleus $^{17}$F are computed
in the framework of microscopic models. The real part of the OP is
calculated by a corresponding folding procedure accounting for the
anti-symmetrization effects, while the imaginary part is obtained
on the base of the high-energy approximation [1]. In the hybrid
model of the optical potential developed and explored in our
previous works [2,3] the only free parameters are the depths of
the real and imaginary parts of the OPs obtained by fitting the
experimental data. A good agreement of the theoretical results
with the available experimental data is achieved pointing out
clearly to a peripheral character of the scattering.\bigskip
[1] V. K. Lukyanov, E. V. Zemlyanaya, and K. V. Lukyanov, Phys.
At. Nucl. {\bf 69}, 240 (2006); JINR Preprint P4-2004-115, Dubna,
2004.[2] K. V. Lukyanov {\it et al.}, Eur. Phys. J. A {\bf 33}, 389
(2007).[3] V. K. Lukyanov {\it et al.}, Phys. Rev. C {\bf 80}, 024609
(2009); Phys. Rev. C {\bf 82}, 024604 (2010); Phys. Rev. C {\bf
88}, 034612 (2013); Phys. Rev. C {\bf 91}, 034606 (2015); Eur.
Phys. J. A {\bf 53}, 31 (2017); Phys. Rev. C {\bf 100}, 034602
(2019).Speaker: Mitko Gaidarov (INRNE-BAS) -
3:15 PM
Coffee break
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18
CLUSTERING AND MICROSCOPICALLY SEPARATED STATES FORMATION IN FISSION POTENTIAL ENERGY CALCULATIONS
Potential Energy calculations are the basis for static and dynamic studies of the nuclear fission process. Calculation of surface, nuclear, Coulomb, rotational functionals, curvature, congruence, and Wigner energy functionals was recently presented for a wide variety of nuclear shape parameterizations [1].
Current approaches typically aim to achieve a theoretical description of the potential energies and shapes of a fissioning system along the conventional fission valleys. In contrast, we study the whole potential energy surface using a realistic mean field and flexible shape parameterization [2], with the aim of treating specific areas of surface related to the new cluster structure formation. To achieve this, we conducted calculations of the regions of maximum energy, saddle points and partly ridges separating the various passes to fission.
Nucleon localization relative to the cluster formation has been studied based on the realistic mean field calculations [3]. Rearrangement of nucleons gives rise to decentralized dynamics in a fissile system in terms of nucleon degrees of freedom.
Decentralized model approach is suggested with the aim of finding specific requirements needed for the new cluster state formation. Clustering could be simulated as a dynamics of neighboring particles. This type of dynamics occurs when particles can autonomously adapt to their environment. There are many examples in nature where adaptability arises from simple decentralized processes [4].References:
1. A.V. Karpov et al., Computer Physics Communications 258, 107605 (2021).
2. V.V. Pashkevich, Y.V. Pyatkov, A.V. Unzhakova, JMP E 19, 718 (2010).
3. A.V. Unzhakova, O.N. Granichin, Exotic Nuclei 351 (2019).
4. Y.V. Ivanskiy et al., Int. Conf. CoDIT, Malta DOI:10.1109/CoDIT.2016.7593526 (2016).Speaker: Dr Anna Unzhakova (Saint Petersburg State University) -
19
Studies of the reactions $^9$Ве$(р,d)$ and $^9$Ве$(р,α)$ in the energy range of 300-1400 keV
At present, at low astrophysical energies there is experimental information on the cross sections of the reactions $^9$Ве$(р,d_0)$ and $^9$Ве$(р,α_0)$ obtained by different authors [1-14]. Nevertheless, as shown in the review [15], the extrapolation of the S-factors of these reactions to zero energy has a large uncertainty (the difference is up to 10 times). This is partly due to the many resonances present at low energies. For reliable extrapolation of experimental data, for example, by the R-matrix method, it is very important to have accurate experimental data in the regions of the maxima and minima of the available resonances. Obtaining these data for the region E$_\text{p, lab.}$= 300 - 1400 keV the present work that has been carried out at the electrostatic tandem accelerator UKP-2-1 of the Institute of Nuclear Physics (Almaty) is devoted. The Be film of natural isotopic composition ($^9$Be ~ 100%) was used as a target. Detailed description of the accelerator and experimental methods can be found in [16, 17] and in their references.
The measurement of the differential cross sections of the reactions 9Ве(р,d0) and $^9$Ве$(р,α_0)$ at the range of angles θ$_\text{lab.}$ = 200 - 1650 with a step of 100 at E$_\text{p, lab.}$ = 400, 600, 940, 1050, 1200, 1300 and 1400 keV have been carried out with an error of about 15%. We also measured the excitation functions of these processes for the angles θ$_\text{lab.}$ = 700 and 1600 in the energy range E$_\text{p, lab.}$ = 300 - 1400 keV with a step of 10 - 20 keV. Within the limits of error, the results of the present experiment coincided with the literature data in the overlapping areas.References:
1. J.A. Neuendorffer, D.R. Inglis, S.S. Hanna, Phys. Rev. 82, 75 (1951).
2. G. Weber, L.W. Davis, J.B. Marion, Phys. Rev. 104, 1307 (1956).
3. G.M. Hudson et al., Nucl. Phys. A 184, 175 (1972).
4. A.J. Sierk, T.A. Tombrello, Nucl. Phys. A 210, 341 (1973).
5. D. Zahnow, C. Rolfs, S. Schmidt, H.P. Trautvetter, Z. Phys. A 359, 211 (1997).
6. C.R. Bruneet al., Phys. Rev. C 57, 3437 (1998).
7. R.B. Day, R.L. Walker, Phys. Rev. 85, 582 (1952).
8. J.B. Marion, J. S. Levin, Phys. Rev. 115, 144 (1959).
9. H.R. Blieden, G.M. Temmer, K.L. Warsh, Nucl. Phys. 49, 209 (1963).
10. T. Yanabuet al., J. Phys.Soc. Japan 19, 1818 (1964).
11. S. Moritaet al., Nucl. Phys. 66, 17 (1965).
12. Q.-G. Wen et al., Phys. Rev. C 78, 035805 (2008).
13. N. Catarino et al., Nucl. Instr. and Meth. B 371, 50 (2016).
14. S. Krat et al., Nucl. Instr. and Meth. B 358, 72 (2015).
15. Yi Xu et al., Nucl. Phys. A 918, 61-169 (2013); http://arxiv.org/abs/1310.7099v1 .
16. N. Burtebayev et al., Phys. Rev. C 78, 035802 (2008).
17. S. Dubovichenko et al., Chinese Physics C 41, 014001-1 (2017).Speaker: D.M. Zazulin (Institute of Nuclear Physics, Almaty, Kazakhstan; Al-Farabi Kazakh National University, Almaty, Kazakhstan) -
20
Cross section measurement of the 13C(α,n0)16O reaction in the 2-6.2 MeV α-particle energy range
The 13C(α,n)16O reaction cross section plays an important role as the background source in the geoneutrinos measurements and as the source of neutrons for the s-process in nuclear nucleosynthesis. The cross section for its reverse reaction is important for the number of practical applications, including the design of the nuclear power plants, the assessment of helium accumulation in structural materials, and dosimetry. The sets of experimental data on this reaction cross section, as well as the evaluation given in different libraries, differ significantly (20-50%) from each other. The report presents the results of measurements performed by the time-of-flight method on a tandem accelerator at IPPE JSC. The thickness and characteristics of the 13C target, as well as the state of the target during measurements, were determined by ion beam analysis methods. The analysis of the influence of multiply scattered neutrons on the measurement results is carried out. The experimental data obtained are compared with the results of other authors and with the evaluated cross sections from the nuclear data libraries.
Speaker: Mr Pavel Prusachenko (IPPE) -
4:50 PM
End of session
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1:35 PM
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physicsConvener: Evgeny Andronov (St Petersburg State University (RU))
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21
Short range correlations investigated by DSS collaboration in deuteron involved reactions
Investigation of the reactions of deuteron elastic scattering and deuteron breakup are interesting from the point of view of nucleon-nucleon (NN) and three nucleon (3N) correlations, special attention is paid to short distances with high transferred momenta. The Deuteron Spin Structure (DSS) collaboration revealed a strong sensitivity to the spin structure of short-range isoscalar NN correlations, this has been observed for elastic dp scattering in deuteron analyzing powers. Spin structure of np short-range correlations was found earlier in the inclusive reaction of Ayy's tensor analyzing power at JINR synchrophasotron. The analysis was performed at different energies in wide areas of fraction of longitudinal xF and the transverse momenta pT of proton. Ayy demonstrates dependence on at least these two internal variables, but the approach used could not describe the data. Effective cross section and analyzing powers of the elastic dp process are obtained and partially processed in the energy range 200 - 2000 MeV. The most interesting energy region we plan to pass through with a step of only 50 MeV. The results are compared with a relativistic model of multiple scattering. The deuteron breakup reaction in the region of hundreds of MeV have rich phase space, by scanning, angular and energetic we can learn more about short-range correlations of nucleons or e.g. on non - nucleonic degrees of freedom depending on the selected part of the phase space. A large influence of relativistic effects was observed in the reaction d (n, np) n at 200 MeV in the configuration where one arm was fixed and the other scanned the angular interval. Contribution from relativistic effects can reach up to 60%. Deuteron - proton breakup reaction is investigated in the energy range 300 - 500 MeV in specific areas of the phase space, where the influence of short-range correlations and in some cases also relativistic effects should be remarkable.
Speaker: Marian Janek (Zilina University, Slovakia) -
22
Thermal multifragmentation in C + Au interactions at 22 GeV incident energies
The analysis of charge distribution (Fig. 1) of intermediate mass fragments (IMF) was performed for interaction of 22 GeV carbon projectiles with a gold terget. The main behavior of charge distribution is well described by a power low with a power function exponent equal to 2.16 $\pm$ 0.03. The power law distribution follows from the classical droplet Fisher model [1], which predicts this behavior of the liquid droplet sizes with the power function exponent equal to 2-3 at the critical point. Experimental data are well described by a combined model INC [2] + SMM [3].
The relative angle correlation of IMF has been studied for $^{12}$C + Au collisions at 22 GeV. Strong suppression at small relative angles is observed caused by Coulomb repulsion of fragments. The time scale for IMF emission is estimated by comparison the measured correlation function to that obtained by the multi-body Coulomb trajectory calculations with time as a parameter. The analysis has been done on an event-by-event basis. The mean decay time of fragmenting system is found to be less than 59 $\pm$ 10 fm/c.
This work was performed at the Dubna Nuclotron with the 4$\pi$ detector array FASA. Calculations were performed using HybriLIT platform of LIT JINR. The research was supported by Grant No. 19-02-00499 A from Russian Foundation for Basic Research.Fig. 1. Charge distribution of IMF produced in C + Au collisions at 22 GeV. Points - experimental data. Solid line - INC + SMM calculations.
- M.E. Fischer, Physics 3, 255 (1967)
- V.D. Toneev et al., Nucl. Phys. A 519, 463 (1990).
- J. Bondorf et al., Phys. Rep. 257, 133 (1995).
- V.V. Kirakosyan et al., Instrum. Exp. Tech. 51, 159 (2008).
Speaker: Dr Sergej Avdeyev (JINR) -
23
Experimental study of the e+e- -> n anti-n process at the VEPP-2000 e+e- collider with the SND detector
The e$^+$e$^-$$\rightarrow$ $\text{n} \bar{\text{n}}$ cross section has been measured in the experiment at the VEPP-2000 e$^+$e$^-$ collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) electromagnetic calorimeter is used to select n anti-n events. The value of the measured cross section from the threshold up to 2 GeV varies from 0.6 to 0.4 nanobarn. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio |GE|/|GM| of the neutron electric and magnetic form factor is obtained from the measured angular distribution and found to be close to 1.
Speaker: Sergey Serednyakov (BINP Novosibirsk) -
24
QUASI-ELASTIC KNCKOUT OF NUCLEON FROM THE SHORT-RANGE NN CORRELATION AND RESCATTERINGS IN THE REACTION 12C+p→10A+ pp+N
Short-range correlated (SRC) NN pairs play an important role in structure of atomic nuclei and are studied using mainly electron beams [1]. A new step was done at BM@N in JINR [2] where the reaction $^{12}$C+p→$^{10}$A+pp+N is studied using the $^{12}$C beam at energy of 4 GeV/nucleon in inverse kinematics providing interaction with the hydrogen target to probe the SRC pairs in the $^{12}$C. In theoretical analysis [3] of the SRC effects in this reaction is used a properly modified approach developed earlier (see Ref. [4] and references therein) to describe the quasi-elastic knock-out of fast deuterons from the light nuclei $^{12}$C and $^{7,6}$Li by protons in the reactions (p,pd) and (p,nd) [5]. Elementary sub-processes in the (p,Nd) were the backward quasi-elastic scattering of the proton on the two-nucleon clusters p{pn}→pd and p{nn}→nd at the proton beam energy 670 MeV. As in Ref. [4], the spectroscopic amplitudes for NN-pairs in the ground state of the $^{12}$C nucleus are calculated here within the translation-invariant shell model (TISM) with mixing configurations. Factorization of the two-nucleon momentum distribution over the internal n$_\text{rel}$ (q$_\text{rel}$) and the c.m.s. n$_\text{cm}$ (k$_\text{c.m.}$) momenta is assumed and for n$_\text{rel}$ (q$_\text{rel}$) the squared deuteron (or singlet deuteron) wave function the CD Bonn NN-interaction potential is used. Relativistic effects in the sub-process p+{NN}$\rightarrow$p+N+N of quasi-elastic knockout of nucleon from the SRC pair are taken into account in the light-front dynamics [6]. We found that the c.m. distribution of the deuteron clusters obtained within the TISM and used in [4], [5] to describe the (p,Nd) data [4] has to be modified considerably [6] to describe the kc.m. distribution of the SCR NN pairs measured in the electron data [7]. The ratio of the spin-singlet to spin-triplet pairs {pp}s/{pn}t is calculated and found to be in agreement with existing data. Here the initial and final state interaction effects are estimated within the eikonal approximation using the Glauber model for the N-$^{10}$A scattering. The one-loop approximation with elastic N-$^{10}$A rescatterings is applied and the effect is found to be moderate.
This work is supported in part by the RFBR grant № 18-02-40046.References:
1. O.Hen et al., Rev. Mod. Phys. 89, 045002 (2017) .
2. M. Patsyuk et al., Nature Phys. 17, 693 (2021); arXiv:2102.02626 [nucl-ex].
3. Yu.N. Uzikov, Izv. RAN, Ser. Fiz. 84 , 580 (2020).
4. M.A. Zhusupov, Yu.N. Uzikov, Fiz. El. Chast. At. Yadr. 18, 323 (1987).
5. J. Ero et al., Nucl. Phys. A 372, 317 (1981); D. Albrecht et al., Nucl. Phys. A 322, 512(1979).
6. Yu.N. Uzikov, EPJ Web Conf. 222, 03027 (2019).
7. E.O. Cohen et al., Phys. Rev. Lett. 121, 092501 (2018).Speaker: Yuriy Uzikov (Joint Institute for Nuclear Researches, M.V. Lomonosov State University, Dubna State University) -
25
Cold Superdense Baryonic Component of Nuclear Matter
Started in the late 1950s at DLNP JINR pioneering experimental studies of proton scattering on nuclei allowed D.I. Blokhintsev assumed the presence in nuclei a lower mass nucleus in a compressed state, i.e. the presence of a cold strongly compressed component in ordinary nuclear matter. The search and study of two- and three-nucleon systems in nuclei continued at DLNP JINR and ITEP (Moscow) and beyond. The investigations were carried out in the kinematic region, outside the kinematics of the nucleon-nucleon interaction. In the future, the processes in this kinematic region were called cumulative processes.
In this report is presented the results of the cumulative processes study outside of the nuclear fragmentation region and with production of particles with the transverse momentum greater than 1 GeV/c. These experiments were carried out with proton and carbon nuclei beams by the IHEP(Protvino) accelerator complex. The data were takeout using the SPIN set up – single-arm magnetic spectrometer. The obtained data showed that the processes of direct knock-out of deuteron and tritium nuclei with momentum up to 6.5 GeV/c are observed. This confirms the presence of deuterons and tritium in the nuclear matter in a highly compressed state, in other words, existing of the cold superdense baryonic component.Speaker: S.S. Shimanskiy (JINR, Dubna) -
3:40 PM
Coffee break
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26
A possibility to register associated pair production of hadrons and light nuclei in a kinematically forbidden region in AA-interactions on the FODS double arm spectrometer at the U-70 accelerator complex (The Monte Carlo simulation)
The possibility to register the associated pair production of hadrons and light nuclei in a kinematically forbidden region in AA-interactions on the FODS double arm spectrometer at the U-70 accelerator complex (Protvino) is analyzed. The value of ion beam energy is 20.5 GeV/nucleon ($\sqrt{s_{NN}}$=6.3 GeV). The mode of measurements with one arm makes it possible to study production of hadrons and nuclei in forward direction at zero angle for values of Feynman variable reaching x=2.5. Here we analyze a variant with activationof both arms. The arms are installed asymmetrically at angles of 128.9 mrad and -268.9 mrad relatively to propagation of the ion beam for South and North arms respectively. This gives ability to register processes with emission of the secondary nucleons and nuclei into forward and backward hemispheres in the center of mass. The purpose of such an experiment is to explicitly reveal the cases of binary interactions, showing the cluster structure of nucleus.
This work was supported by the grant from the Russian Foundation for Basic Research Но.19-02-00278.Speaker: Mikhail Bogolyubsky (NRC Kurchatov Institute - IHEP) -
27
DESCRIPTION OF THE SPECTRA OF CUMULATIVE PROTONS, PIONS AND PHOTONS IN COLLISIONS OF HEAVY IONS WITH INTERMEDIATE ENERGY BASED ON THE HYDRODYNAMIC APPROACH
$\bf{A.T. D’yachenko^{1,2}, I.A. Mitropolsky^{2}}$
$^{1}$Emperor Alexander I Petersburg State Transport University, St. Petersburg, Russia
$^{2}$ B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Gatchina, RussiaOn the basis of the hydrodynamic approach with a nonequilibrium equation of state [1-3], collisions with a beryllium target of $^{12}$C nuclei at energies of 0.3-3.2 GeV per nucleon, studied at the ITEP accelerator, with the emission of protons [4], pions [5] and photons [6] are considered. Experimental proton spectra contain a high-energy cumulative part, as well as a soft part, to which fragmentation contributes. We were able to describe the cumulative part of the proton spectrum [2] within the framework of the nonequilibrium hydrodynamic approach, taking into account the nuclear viscosity and the correction for the microcanonical distribution [2] and to supplement the calculations with the proton contribution based on the statistical mechanism of fragmentation in the soft region of the spectrum [3]. Distinguishing the compression stage, the expansion stage, and the spread stage with the formation of secondary particles, we described the experimental inclusive double differential cross sections for the emission of pions at an energy of 3.2 GeV per nucleon for carbon nuclei [5], which were presented recently, as well as the emission of hard photons [6], presented earlier.In our approach, the description of the cumulative spectra of secondary particles is achieved due to the isolation and hydrodynamic evolution of local heating - hot spot in the overlap region of colliding heavy ions. We also considered the emission of protons and pions for various nuclei at the energies of the SIS accelerator (GSI). Agreement with the experimental data is achieved without introducing fitting parameters, and can be extended to the energy range of the NICA accelerator complex under construction in Dubna.
1.A.T. D’yachenko, K.A. Gridnev, W. Greiner, J. Phys. G $\bf{40}$, 085101 (2013)
2.A.T. D’yachenko, I.A. Mitropolsky, Phys. Atom. Nucl. $\bf{83}$, 558 (2020)
3.A.T. D’yachenko, I.A. Mitropolsky, Bull. Russ. Acad. Sci. Phys. $\bf{85}$, 554 (2021)
4.B.M. Abramov et al., Phys. Atom. Nucl. $\bf{78}$, 373 (2015)
5.V.V. Kulikov et al., Phys. Atom. Nucl. $\bf{84}$, no.4 (2021)Book of Abstracts of LXX Int. Conference “Nucleus-2020” P. 168
6.I.G. Alekseev et al., Phys. Atom. Nucl. $\bf{78}$, 936 (2015)Speaker: Prof. Alexander D'yachenko (Petersburg State Transport University) -
28
Quark-Gluon Plasma is appeared in collisions of medium nuclei at higher energies than in heavy ion interactions
Recently the NA61/SHINE collaboration has published new experimental data on Pi- meson production in Ar-40+Sc-45 interactions at projectile nucleus laboratory momenta 13, 19, 30, 40, 75 and 150 GeV/c/N. The data are analyzed in Epos LHC, Epos 1.99 and Geant4 FTF models. The data were obtained for 0 - 5 % centrality interactions. In order to imitate the centrality selection we choose impact parameters intervals 0 - 2.5, 0 - 2.9, and 0 - 3.1 fm for the pointed models, correspondently, normalizing model results on experimental data at 19A GeV/c. In the case, the model results are in agreement with each other and experimental data at momenta below 75A GeV. At higher energies, only Epos LHC gives satisfactorily results. Epos 1.99 and Geant4 FTF model essentially underestimate the data. Two last models are pure hadronic models. The Epos LHC considers collective hadronization which simulates QGP effects. Earlier, irregularities in particle production were observed in heavy ion collisions at energies above 20*A GeV/c (NA49 analysis).
Speaker: Prof. V. Uzhinsky and A. Galoyan (Joint Institute for Nuclear Research (RU)) -
29
z-Scaling and Search for Signatures of Phase Transition in Nuclear Matter
The concepts of "scaling" and "universality" have been developed to study critical phenomena. Scaling implies that systems near a critical point (CP) exhibit self-similarity and are invariant with respect to scale transformations. The universality of their behavior lies in the fact that vastly different systems behave in a similar way near the respective CP.
We present some results of analysis of hadron production in $p+p$ and $A+A$ collisions obtained in the framework of $z$-scaling in searching for signatures of a phase transition in nuclear matter. This approach is one of the methods allowing systematic analysis of experimental data on inclusive cross sections over a wide range of the collision energies, multiplicity densities, transverse momenta, and angles of various particles. The concept of the $z$-scaling is based on the principles of self-similarity, locality and fractality reflecting general features of particle interactions. The self-similarity variable $z$ is a function of the momentum fractions $x_1$ and $x_2$ of the colliding objects carried by interacting hadron constituents and depends on the fractions $y_a$ and $y_b$ of the scattered and recoil constituents carried by the inclusive particle and its recoil counterpart. The scaling function $\psi(z)$ is expressed via inclusive cross-section, multiplicity density and three model parameters. Structure of the colliding objects and fragmentation processes is characterized by the structural and fragmentation fractal dimensions $\delta$ and $\epsilon$, respectively. The produced medium is described by a "specific heat" $c$. The function $\psi(z)$ reveals energy, multiplicity, angular and flavor independence found in analyses of inclusive spectra measured at the ISR, SPS, Tevatron, RHIC and LHC. A microscopic scenario of hadron production in terms of constituent momentum fractions and recoil mass of produced system is developed. The constituent energy loss as a function of energy and centrality of collision and transverse momentum of inclusive particle is estimated in the $z$-scaling approach. Discontinuity of the model parameters - the fractal and fragmentation dimensions and "heat capacity" - are discussed from the point of view of the search for a phase transitions in the nuclear matter.
- M. Tokarev, A. Kechechyan, I. Zborovsky, Nucl. Phys. A 993, 121646 (2020).
- M. Tokarev et al., Phys. Part. Nucl. 51, 141 (2020).
- I. Zborovsky, Int. J. Mod. Phys. A 33, 1850057 (2018).
- M. Tokarev, I. Zborovsky, Int. J. Mod. Phys. A 32, 1750029 (2017).
- I. Zborovsky, M. Tokarev, Phys. Part. Nucl. Lett. 18, 302 (2021).
Speaker: Prof. Mikhail Tokarev (Joint Institute for Nuclear Research) -
30
Correlation in $^{8}Be$ nuclei formation and $\alpha$-particle multiplicities in fragmentation of relativistic nuclei
In the events of peripheral dissociation of relativistic nuclei in the nuclear track emulsion, it is possible to study the emerging ensembles of He and H nuclei, including those from decays of the unstable $^{8}$Be and $^{9}$B nuclei, as well as the Hoyle state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2$\alpha$-pairs, 2$\alpha p$- and 3$\alpha$-triplets in the approximation of conservation of momentum per nucleon of the primary nucleus. In the same approach, it is possible to search for more complex states. Correlation between the formation of $^{8}$Be nuclei and the multiplicity of accompanying $\alpha$-particles in the dissociation of relativistic $^{16}$О, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei are investigated. On this basis, estimates of such a correlation are presented for the unstable $^{9}$B nucleus and the Hoyle state. An enhancement in the $^{8}$Be contribution to dissociation with the $\alpha$-particle multiplicity is found. It is shown that decays of $^{9}$B nuclei and Hoyle states follow the same trend.
Speaker: Andrei Zaitcev (Joint Institute for Nuclear Research (RU))
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21
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physics: FlowConvener: Vladislav Sandul (St Petersburg State University (RU))
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31
Proton directed flow relative to the spectator plane in Ag+Ag collisions at 1.23A and 1.58A GeV with HADES
We report a new measurement of proton directed flow $v_1$ relative to the spectator plane for Ag+Ag collisions at the beam energies of 1.23A and 1.58A GeV recorded by the HADES experiment at GSI. The projectile spectator plane is estimated using signals of the charged fragments registered with the HADES forward hodoscope. Directed flow is presented differentially as a function of transverse momentum and rapidity in different centrality classes. The slope of $v_1$ at midrapidity, $dv_1/dy$, is reported as a function of centrality and collision energy. The new results extend the existing data available from the previous HADES measurements of directed flow in Au+Au collisions at the beam energy of 1.23A GeV. Sensitivity of the directed flow to the initial angular momentum and connection with the measurement of the lambda hyperon directed flow and global polarization are discussed.
Speaker: Mikhail Mamaev (NRNU MEPhI) -
32
Scaling of collective flow of charged and identified hadrons in Au+Au collisions at $\sqrt{s_{NN}} = 11.5 - 62.4$ GeV from the STAR experiment
Author: Alexey Povarov (for the STAR Collaboration)
National Research Nuclear University MEPhI (NRNU MEPhI)Heavy-ion collisions create matter which is characterized by high temperature and energy density, called Quark-Gluon Plasma (QGP). Azimuthal anisotropy of produced particles is sensitive to the transport properties of QGP (the equation of state, speed of sound and specific shear viscosity) and may provide information about initial state of the collision. In this work, we report results for elliptic ($\upsilon_{2}$) and triangular ($\upsilon_{3}$) flow of charged and identified hadrons ($\pi^{\pm}, K^{\pm}, p, \bar{p}$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 11.5, 14.5, 19.6, 27, 39 and 62.4 GeV from the STAR experiment at RHIC. Measurements of the collective flow coefficients $\upsilon_{2}$ and $\upsilon_{3}$ are presented as a function of particle transverse momenta ($p_{T}$) and collision centrality. In addition the number of constituent quark scaling will be presented for these energies.
Speaker: Alexey Povarov (NRNU MEPhI) -
33
Search for the Chiral Magnetic Wave using the ALICE detector in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} =$ 5.02 TeV
In heavy-ion collisions, a strong magnetic field ($\sim$ 10$^{15}$ T) is expected to be created, which together with the presence of a non-zero electric and axial charge density, can lead to vector and axial currents in the produced system called the Chiral Magnetic Effect (CME) and Chiral Separation Effect (CSE), respectively. Their coupling gives rise to a collective excitation in the quark-gluon plasma (QGP) called the Chiral Magnetic Wave (CMW), causing a charge-dependent elliptic flow, $v_{2}$. As a result, the normalized difference of $v_{2}$ of positive and negative charges, ($\Delta v_{2_{\mathrm{Norm}}}$), may exhibit a positive slope as a function of the asymmetry ($A_{\mathrm{ch}}$) in the number of positively and negatively charged particles in an event. However, non-CMW mechanisms like Local Charge Conservation (LCC) can also lead to a similar dependence of $v_{2_{\mathrm{Norm}}}$ on $A_{\mathrm{ch}}$. A similar measurement with $v_{3}$ can probe the effect of LCC as we expect it not to be affected by the CMW.
In this talk, we present ALICE measurement of $v_{2}$, $\Delta v_{2_{\mathrm{Norm}}}$, $v_{3}$ and $\Delta v_{3_{\rm{Norm}}}$ of charged hadrons in $0.2 < p_{\mathrm{T}} < 1.0$~GeV/$c$ and pions in $0.2 < p_{\mathrm{T}} < 0.5$~GeV/$c$ as a function of $A_{\mathrm{ch}}$ in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} =$ 5.02 TeV. The slope parameters corresponding to $v_{2_{\mathrm{Norm}}}$ and $v_{3_{\mathrm{Norm}}}$ versus $A_{\mathrm{ch}}$ are measured as a function of collision centrality to search for the CMW phenomena at LHC energies. We will also compare the ALICE results with those from the CMS experiment and lower collision energy STAR experiment and also with different model predictions.
Speaker: Prottay Das (National Institute of Science Education and Research (IN)) -
34
Study of the beam energy dependence of anisotropic flow in relativistic heavy ion collisions using scaling relations.
Anisotropic flow measurements of produced particles in relativistic heavy-ion collisions play an essential role in the studies of transport properties of the strongly interacting metter.
In this work we provide the results of the most comprehensive systematic study of the beam energy dependence of anisotropic flow based on existing data and discuss them using different scaling relationsfor azimuthal anisotropy.Speaker: Arkadiy Taranenko (NRNU MEPhI) -
35
Anisotropic flow at energies $\sqrt{s_{NN}}$=2-11 GeV
Multi-Purpose Detector (MPD) experiment at NICA collider has the potential for discoveries in the area of QCD phase diagram with high net baryon densities and moderate temperatures. Anisotropic transverse flow is one of the key observables to study the properties of matter created in heavy-ion collisions. The directed and elliptic flow were studied at the beam energy range $\sqrt{s_{NN}}$=2-11 GeV corresponding to HADES (SIS18), BMN (Nuclotron), and MPD (NICA) experiments. Comparison of the existing experimental data with different heavy-ion event generators is employed to provide a useful tool for feasibility studies at the MPD experiment.
Speaker: Mr Peter Parfenov (NRNU MEPhI) -
3:40 PM
Coffee break
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36
Performance of the CBM experiment at FAIR for measurement of charged hadron anisotropic flow
The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using collisions of heavy ions at center-of-mass energies of a few GeV per nucleon. Anisotropic transverse flow is among the key observables to study the properties of matter created in such collisions. The CBM performance for charged hadron anisotropic flow measurements is studied with Monte-Carlo simulations using gold ions at SIS-100 energies with lab momentum up to 12A GeV/c employing different heavy-ion event generators. Various combinations of CBM detector subsystems are used to investigate the possible systematic biases in flow measurement and to study the effects of detector azimuthal non-uniformity. The resulting performance of CBM for flow measurements is demonstrated for different harmonics of identified charged hadron anisotropic flow as a function of rapidity and transverse momentum in different centrality classes.
Speaker: Oleg Golosov (National Research Nuclear University MEPhI (RU)) -
37
CBM performance for the measurement of $\Lambda$ hyperon’s directed flow in Au+Au collisions at FAIR SIS-100 energies
Oleksii Lubynets $^{(1, 2)}$ and Ilya Selyuzhenkov $^{(1, 3)}$ for the CBM Collaboration
$^{(1)}$ GSI, Darmstadt, Germany
$^{(2)}$ Goethe Universität Frankfurt, Frankfurt am Main, Germany
$^{(3)}$ NRNU MEPhI, Moscow, Russia
The main goal of the CBM experiment is to study highly compressed baryonic matter
produced in collisions of heavy ions. The SIS-100 accelerator at FAIR will give a possibility
to investigate the QCD matter at temperatures up to about 120 MeV and net baryon
densities 5-6 times the normal nuclear density. Hyperons produced during the dense phase
of a heavy-ion collision provide information about the equation of state of the QCD matter.
The measurement of their anisotropic flow is important for understanding the dynamics and
evolution of the QCD matter created in the collision.
We will present the status of the performance studies for Λ hyperon directed flow
measurement with the CBM experiment at FAIR. Λ hyperons decay within the CBM detector
volume and are reconstructed via their decay topology. The Particle-Finder Simple package,
which provides an interface to the Kalman Filter Particle (KFParticle) mathematics, is used to
reconstruct $\Lambda \rightarrow p+\pi^-$ decay kinematics and to optimize criteria for $\Lambda$ hyperon candidate
selection. Directed flow of $\Lambda$ hyperons calculated using different flow measurement
techniques is studied as a function of rapidity, transverse momentum and collision centrality.
The effects on flow measurement due to non-uniformity of the CBM detector response in the
azimuthal angle, transverse momentum and rapidity are corrected using the QnTools
analysis package.Speaker: Mr Oleksii Lubynets (GSI Helmholtzzentrum für Schwerionenforschung) -
38
Relative elliptic flow fluctuations at NICA energy regime
The main aim of the MPD experiment at the future collider NICA is to study the strongly interacting matter created in the heavy-ion collisions at center-of-mass energies $\sqrt{s_{NN}}$ = 4-11 GeV. The azimuthal anisotropy is a key observable in such collisions as its sensitivity to the transport properties and equation of state of the created matter. The relative elliptic flow fluctuations are of intense interest since they can be used as a probe for the initial conditions using the ratio of cumulants $v_2\{4\}/v_2\{2\}$. State-of-the-art models of heavy-ion collisions: UrQMD, AMPT, and vHLLE+UrQMD are employed for the study of relative elliptic flow fluctuations at the NICA energy regime.
Speaker: Vinh Luong (National Research Nuclear University MEPhI (RU)) -
39
A multiharmonic/large-order flow cumulant analysis for relativistic heavy-ion collisions
In the past years, significant progress has happened in high-energy nuclear physics models. A more robust and quantitative picture has replaced the qualitative descriptions of heavy nuclei collisions in the earlier days, enabling us to have a clearer picture of different stages of a heavy-ion collision. These models typically have $O(10)$ free parameters that are tuned by Bayesian analysis in recent years. To better understand the free parameter values, it is essential to experimentally probe their phase space by observables, each containing independent information of the model.
In this presentation, our focus is on anisotropic flow observables. We introduce a method to extract anisotropic flow cumulant systematically. Employing a Monte Carlo simulation tuned by Bayesian analysis results, we predict the value of some abandoned low-order flow harmonic cumulants with significant signals that have not been measured at the LHC. Moreover, we introduce a new method to extract the linear and nonlinear hydrodynamic response coefficients based on our multiharmonic cumulant study. Besides, this systematic study enables us to propose a genuine three-particle correlation function for the first time. This observable is a summation of all third-order flow harmonic cumulants of all harmonics. The large-order flow cumulant ($v_n\{2k\}$ with large $k$) contains a unique piece of information about the underlying flow distribution. In particular, we discuss the relation between the nonvanishing Lee-Yang zero phase and large-order flow cumulant ratios at ultra-central, ultra-peripheral, large, and small collision systems.Based on:
1. S. F. Taghavi, (2020), arXiv:2005.04742 [nucl-th] (will be appeared in Eur.Phys.J.C)Speaker: Seyed Farid Taghavi (Technische Universitaet Muenchen (DE)) -
40
The effect of different centrality determination on the elliptic flow measurements
One of the methods for studying the transport properties of QCD matter at extreme temperatures and energy densities is the study of anisotropic flow. The precise definition of centrality is an important task since directed and elliptic flow coefficients are dependent on centrality. Two methods of centrality determination were considered to study the effect of different centrality determination on the elliptic flow measurements. The first method is based on the Glauber model, and the second is based on inverse Bayes' theorem together with the geometric properties of the collision. Comparison of elliptic flow with centrality determination methods based on both charged particle multiplicity in TPC and the energy deposited in the forward calorimeters FHCal will be presented.
Speaker: Dim Idrisov (MEPHI)
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31
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Section 8. Nuclear medicineConvener: Nikolai Maltcev (St. Petersburg State University (RU))
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41
Development of new methods for medical radionuclide production for radioisotope complex at NRC “KI” - PNPI
At NRC “KI” - PNPI (National Research Center “Kurchatov Institute” - Petersburg Nuclear Physics Institute) the cyclotron C-80 capable of producing 40–80 MeV proton beam with a current of 100 $\mu$A has been constructed. One of the main goals of C-80 is production of a wide spectrum of medical radionuclides for diagnostics and therapy. A special beam line will be erected as well for the treatment of malignant eye diseases. Currently a project is being worked out for the construction of radioisotope complex with three target stations at the beam of C-80. The peculiarity of the proposed facility is the use of the mass-separator with the target-ion source device as one of the target stations for on-line, or semi on-line production of a high purity separated medical radionuclides. The radionuclides planned to be produced are $^{64,67}$Cu, $^{68}$Ge, $^{82}$Sr, $^{111}$In, $^{123,124}$I, $^{223,224}$Ra, $^{225}$Ac and others, believed to be promising for diagnostics and therapy. Presently new thermal methods for selective production of radionuclide pointed out are being developed. The general idea is to use the difference in volatility of atoms of the needed radionuclide and target material when it is heated in a high vacuum at definite temperature. The results of a new high temperature method utilization for separation of $^{67}$Cu, $^{82}$Sr from irradiated target materials have been presented. Also the results of experiments for the production of radioisotopes $^{223,224}$Ra and $^{225}$Ac by the mass-separator method are discussed. It is important to emphasize that the method of “dry” thermal separation allows the subsequent use of the mass-separator method for further purification of the targeted radionuclides.
Speaker: Vladimir Panteleev (Petersburg Nuclear Physics Institute of National Research Center “Kurchatov Institute”, Gatchina, Russia) -
42
STUDY OF DOSE TRANSMISSION IN A MULTILEAF COLLIMATOR ON A VARIAN HALCYON ACCELERATOR
The study of dose transmission is a vital topic because the number of patients who have developed delayed radiation injuries increases every year [2,3].
Recently commissioned linear accelerator Varian Halcyon V1.0 (Varian Medical Systems, Palo Alto, Calif., USA) without collimation shutters is now gaining popularity in oncology clinics. The Halcyon MLC System features the stacked and staggered dual‐layer multileaf collimator. The primary and secondary collimators are fixed; there is no flattering filter [1, 4].
This study aims to measure dose transmission from a Varian Halcyon multileaf collimator experimentally. Our experiments were carried out on the Varian Halcyon linear accelerator with a boundary photon energy of 6 MeV:
- Investigation of the effect of field size on dose transmission. IMRT plans were created to irradiate the phantom with different sized fields in the treatment planning system Eclipse. The dose profile was measured with an IC Profiler SunNuclear array detector. A water-equivalent Solid Water GAMMEX phantom was used. The data obtained were used to plot the beam profiles. All received doses were normalized to a absorbed dose in a 10 × 10 cm2 reference field at a depth of 10 cm.
- Measurement of dose transmission at a small field size. In this experiment, a plan was created to irradiate the 3D Scanner SunNuclear water phantom. The multileaf collimator was positioned to create a rectangular beam size 1x2 cm2. The SNC125c ionization chamber was used.
The experiment showed that despite the fact that in all experiments, the same dose of 200 monitor units was applied, the dose transmission becomes larger with increasing field size. At a distance of 16 cm from the central axis, doses of 0.003, 0.012, 0.029, 0.052, 0.092, 0.128 Gy are observed for fields with sizes 5x5, 10x10, 15x15, 20x20, 25x25 cm2, respectively.
The results of the current study are essential for understanding how field size affects dose transmission.
Bibliography:
- Lim TY, Dragojević I, Hoffman D, Flores‐Martinez E, Kim GY. Characterization of the Halcyon TM multi-leaf collimator system. J Appl Clin Med Phys. 20: 106– 114 (2019);
- NCRP, NCRP Report 170. Second Primary Cancers and Cardiovascular Disease After Radiation Therapy. Bethesda, Md: National Council on Radiation Protection and Measurements (2011);
- Takam R, Bezak E, Marcu LG, Yeoh E. Out-of-field neutron and leakage photon exposures and the associated risk of second cancers in high-energy photon radiotherapy: current status. Radiat Res. 176:508–520 (2011);
- Varian Medical Systems. Halcyon Brochure. 2017 URL: https://www.varian.com/sites/default/files/resource_attachments/Halcyon_brochure_RAD10443B_092417.pdf.
Speaker: Elena Morozova -
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STUDY OF DOSE-ENHANCING AGENTS ON BREMSSTRAHLUNG PHOTONS FROM SL75-5MT MEDICAL ACCELERATOR
Author: Vladimir Skorkin
Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia
Corresponding Author: skorkin@inr.ru
Contrast-enhanced radiotherapy allows to enhance the radiation dose absorbed by the tumor when using the hard elements (I, Gd, Au, Bi, etc.) for a photon absorption [1]. The dose-enhancing agents have a better absorption capacity, than biological tissues and thus sparing the surrounding healthy cells. In [2], an increase dose absorbed by iodinated water (for 50 mg/ml iodine concentrations) was obtained at using bremsstrahlung photons generated by the clinical linear electron accelerator SL75-5MT. Normally, dose-enhancing agent concentrations employ up to 15 mg/ml.
In our work, we investigated the possibility of using metal-organic composites containing dose-increasing agents to increase the absorption of SL75-5MT bremsstrahlung photons. The present study aims to assess feasibility of using of the metal-organic composites SL75-5MT bremsstrahlung photons to increase radiation absorbed by [3]. The linear accelerator 0.5-4.5 MeV photons (80% of total flux and 2 Gray/min absorbed dose) created secondary X-rays and electrons in the dose-enhancing metallic agents of the metal-organic composites. This is enhanced the radiation dose absorbed by the tumor. The dose absorbed by tissue-equivalent phantom with metallic agents (Cd, Au, W, Bi, Pb) was measured by PTW MULTIDOS dosimetry with clinical ionization chambers. In addition, a gamma radiation from the phantom were measured using BDMG-08R gamma detectors. For Au, Bi, Pb dose-enhancing agents the absorbed dose increased by 10-20%. The significant increase in the absorbed dose (> 50%) was observed from d(γ,n)p reaction when using deuterated water instead of tissue-equivalent phantom. Therefore, it is possible to employing deuterated water for photon energy spectra of SL75-5MT clinical accelerator in order to reach a therapeutically significant effect.
References:
1. Koryakin S.N. at al, Rossiyskiy biotherapevticheskiy jurnal. 15, 52 (2016).
2. Vorobyeva E.S. at al, Bulletin of RSMU. 4, 57 (2017).
3. Burmistrov Yu.M. at al, J. Surface Investigat. 13, 195 (2019).Speaker: Vladimir Skorkin (INR RAS) -
44
Enhanced production cross sections of $^{123,124,126,128}$I via incomplete fusion reactions: scope in nuclear medicine
It has been a constant research endeavor to find new ways of producing radionuclides for diagnostic and therapeutic purposes in nuclear medicine. The research area has ever grown due to technological developments and facilities like heavy-ion accelerators. The iodine isotopes e.g., $^{131}$I has been widely used as a radiotracer for thyroid-related diseases. This neutron-rich isotope ($^{131}$I) is produced using a reactor. Although often difficult to procure locally, but it can be transported easily because of its long lifetime ($\tau_{1/2}$= 8.04 d). Another isotope $^{123}$I produced using cyclotron, is also utilized in recent times. The suitable $\gamma$-ray energy (E$_\gamma$) region is 100-600 keV which is high enough to be sufficiently penetrating through the medium of the human body, and can be fully absorbed in the detector. These two isotopes of iodine – $^{131}$I emitting the photon of energy 364 keV and $^{123}$I of energy 159 keV – qualify the requirement.
We investigated the production of four isotopes of iodine $^{123,124,126,128}$I via incomplete fusion reactions (ICF) by bombarding the beams of $^{10,11}$B (60-78 MeV) on $^{122,124}$Sn foils using the 14-UD Pelletron accelerator at the Tata Institute of Fundamental Research, Mumbai, India. The experimental results for our initial experiment $^{11}$B+$^{122}$Sn were presented [1] in the conference NN2012. Later, we utilized the same experimental procedure for the other reactions as well. Our purpose was two-fold. Firstly, to measure the cross sections of all the long-lived (minutes to days) reaction products using the off-line γ-ray spectrometry. The main products (Cesium nuclei) of the complete fusion reactions (CF) were produced with high cross sections as expected, and were in the good agreement with the statistical model code PACE4 [2] predictions. Secondly, our main objective was to identify all the ICF products – with enhanced cross sections over the PACE4 predictions – and understand the reaction mechanism. Special attention was paid to iodine isotopes because of their relevance in nuclear medicine. Our results turned out to be quite promising. All the iodine isotopes produced through ICF (α-channels) – $^{123}$I ($\tau_{1/2}$= 13.2 h, E$_\gamma$=159 keV), $^{124}$I ($\tau_{1/2}$= 4.2 d, E$_\gamma$=603 keV), $^{126}$I ($\tau_{1/2}$= 12.9 d, E$_\gamma$=389 keV), and $^{128}$I ($\tau_{1/2}$= 25 m, E$_\gamma$=443 keV) – were suitable radiotracers because of long lifetimes and $\gamma$-ray energies. Moreover, through the process of ICF reactions their cross sections were an order of magnitude higher than the expected CF process.
Earlier works on ICF reactions in literature were carried out at high beam energies, and the sum rule model (original-SRM) [3] was quite successful in explaining the observed results. However, the original-SRM underestimated the ICF cross sections at our utilized low beam energies. We therefore made modification in the model mainly to incorporate the energy dependence in the definition of critical angular momentum. Using our modified-SRM, we found a significant improvement in predicting the enhancement in the cross sections. The present work has much potential in nuclear medicine, as it can improve the accessibility of many iodine isotopes for the better scope in their utilization and circulation.
1. B. Bhujang et al., Journal of Physics: Conference Series 420, 012128 (2013).
2. A. Gavron, Phys. Rev. C 21, 230 (1980).
3. J. Wilczyński et al., Phys. Rev. Lett. 45, 606 (1980).Speaker: Pragya Das (Indian Institute of Technology Bombay) -
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3D visualization of radiotracers for SPECT imaging using a Timepix detector with a coded aperture
The report contains a description of the SPECT system based on the Timepix detector with a coding aperture developed at DLNP JINR. Using a semiconductor pixeled detector with CdTe sensor and Timepix readout chip allows conduct research using multinuclide radiopharmaceuticals with high energy and submillimeter spatial resolution for laboratory animals. Are given the main characteristics of the resulting system, examples are shown 2D and 3D images obtained with calibration phantoms. Is being discussed possible development of the system, including changing the field of view and spatial resolution, as well as the ability to create on the basis SPECT / CT scanner installations. The characteristics of the installation are compared with commercial counterparts.
Speaker: Vladislav Rozhkov (JINR)
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3:40 PM
Coffee break
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Section 7. Synchrotron and neutron studies and infrastructure for their implementationConvener: Nikolai Maltcev (St. Petersburg State University (RU))
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Advanced cold neutron source for HEC-3 at the reactor PIK (status & performances)
Several cold neutron sources (CNS) are planned to be built at the reactor PIK. Two of them are planned to be mainly used for condensed matter physics. They will produce cold neutrons in the horizontal experimental channels HEC-3 and HEC-2 with highest brightness. Neutron source for the channel
HEC-3 will be mounted in the vertical vacuum tube placed in the heavy water reactor reflector [1]. The chamber of spherical form filled with liquid deuterium will be placed into the tube. The operation temperature of the deuterium is in the range of 21 – 25 K, and the volume of it is about 24.6 liters. The chamber has a displacer of special form to increase the neutron brightness of the source. The CNS will be operated in two modes: the normal mode with the chamber filled with liquid deuterium and the standby mode without deuterium. In both cases the released heat in the chamber will be removed with the special helium loop. Heat load in the chamber and in the other elements of the source placed in the vertical tube was calculated using MCNP code and the full computer model of the reactor. It includes prompt neutron and gamma heat releases as well as heat release from the decay gamma radiation from the reactor core as well as from the activation products of the reactor and CNS constructional materials. Also, the impact of the β-decay radiation was included. Tritium production in the deuterium was evaluated as well as the activity of the deuterium along the reactor operation.
There is also a special neutron reflector in the tube between the chamber and a heat exchanger. The purpose of the reflector is to increase the brightness of the source as well as to reduce the activation of constructional materials in the upper part of the CNS.
The neutron guide system of CNS HEC-3 is also described as well as setups in the experimental hall and in the hall of horizontal channels which are planning to use these cold neutrons.- V.A. Mityukhlyaev et al. Neutron-physical calculations for the CNS HEC-3 of reactor PIK. Preprint PNPI # 2959 (2014)
Speaker: Victor Mityukhlyaev (NRC «Kurchatov Institute» - PNPI) -
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Development of the high-brightness HEC-2 cold neutron source at the reactor PIK
The main goal of the created cold neutron source on horizontal experimental channel HEC-2 of reactor PIK is to obtain the maximal neutron brightness. There are two main possibilities for using two different material as a main body in the thermalisation chamber of the source: the liquid deuterium or the parahydrogen. When using optimal size and form of the chambers they give nearly equal brightnesses of the source. There are different pro and contra for using each of this options. Here we made the comparison of these two possibilities within neutron physical calculations.
Liquid deuterium as well as liquid hydrogen may present in two spin state in the mixtures: para- and ortho- states. Inelastic cross-section of para- and ortho- deuterium are similar but for hydrogen they are strongly different at energies smaller then 1 meV. For this reason the optimal form of the maximal brightness deuterium and hydrogen chambers will be strongly different. They will also have different heat loads. The brightness of the sources depends also on the position of the chambers in the heavy water reflector toward the reactor core. We made the optimization calculation of the form and the position of the liquid deuterium chamber to provide the maximal brightness of it and compare the obtained brightness and heat load with the brightness and heat load of the parahydrogen chamber of optimal size placed in the same position.Speaker: Mikhail Onegin (Petersburg Nuclear Physics Institute) -
48
The development of Nuclear Security Culture in the Republic of Belarus in 2020-2021
Nuclear security culture is an essential means for nuclear security enhancement. It contributes to the ability of personnel to effectively mitigate potential threats to nuclear and radioactive material by promoting appropriate attitude and behavior that result in personnel adopting a more rigorous and prudent approach to their nuclear security responsibilities. Within organizations that have a strong nuclear security culture it is less likely that personnel will commit a malicious act, either due to their belief that nuclear security is important or to the deterrence factor of vigilance and professional adherence to nuclear security practices.
This paper is a continuation of the «Advanced Nuclear Security Program at The Joint Institute for Power and Nuclear Research – Sosny» [1] which reflects the process of nuclear security culture implementation and strengthening. The authors touched upon the development of nuclear security culture in the Republic of Belarus in 2020-2021. This time coincides with the period of the first unit of Belarusian Nuclear Power Plant in Ostovets commissioning on the one hand, and with the spread of COVID-19 on the other.
The role of nuclear security culture has increased as reflected in a number of regulations approved 2020:
• Requirements and rules for ensuring nuclear and radiation safety «General provisions for nuclear power plants safety insurance» [2]
• Requirements and rules for ensuring nuclear and radiation safety «Safety when handling ionizing radiation sources. General provisions.» [3]
Role, functions and requirements for nuclear security culture are set forth not only for Belarusian nuclear power plant [2], but also for organizations operating ionizing radiation sources [3].
Presently, we all are living in a time of COVID-19 spread. Sanitary standards establishment has made corrections to organization of activities necessary for development and strengthening of nuclear security culture in organizations.
The paper presents the approach and lists the activities organized by the Scientific Institution “JIPNR - Sosny” to improve nuclear security culture.References
1. T Korbut et al, J. Phys.: Conf. Ser. 1689 012014 (2020)
2. Ministry for Emergency Situations of the Republic of Belarus Requirements and rules for ensuring nuclear and radiation safety «General provisions for nuclear power plants safety insurance» 8/35399 (2020)
3. Ministry for Emergency Situations of the Republic of Belarus Requirements and rules for ensuring nuclear and radiation safety «Safety when handling ionizing radiation sources. General provisions» 8/36169 (2020)Speaker: Mrs Tamara Korbut (Scientific Institution "JIPNR-Sosny")
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Section 6. Plasma physics and thermonuclear fusion.Convener: Nikolai Maltcev (St. Petersburg State University (RU))
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ON THE POSSIBILITY OF OBSERVING THE STIMULATED DE-EXCITATION OF THE NUCLEAR ISOMER 186mRe IN THE PLASMA OF Z-PINCH AT THE ANGARA-5-1 FACILITY
In ref. [1] a laser plasma with an electron temperature Θe ~ 1 keV, a lifetime of about 0.3 ns and a mass of ~ 1 μg was obtained from metallic rhenium containing isomeric nuclei of the 186mRe (T1/2, m = 2∙105 y). In such a plasma, there was observed stimulated de-excitation of isomeric 186mRe nuclei with a probability Pstim ~ 10 – 7, which was determined after a laser shot by the degree of disequilibrium between the decay of the isomers and the 186Re nuclei in the ground state (T1/2, g = 91 h).
The probability Pstim is proportional to the plasma lifetime, and to enhance the effect, it was proposed in ref. [2] to use instead of laser plasma an electric discharge plasma with the 186mRe isomeric nuclei, the lifetime of which increases up to ~ 10 ns while maintaining the temperature Θe ~ 1 keV. Such a plasma can be obtained in high-current Z-pinches at the Angara-5-1 facility at the JSC TRINITY. The plasma is formed during the implosion of a two-cascade cylindrical multi-wire assembly (liner) when a current pulse of ~ 4 MA passes through it, with a voltage of 1 MV and a duration of ~ 100 ns [3]. The outer cascade with a diameter of 12 mm with mass of ~ 300 μg/cm per unit liner length is composed of aluminum wires, the inner cascade with a diameter of 6 mm and a linear mass of ~ 20 μg/cm is composed of tungsten wires with a diameter of 6 μm. The material of the pinch plasma is mainly deposited at the ends of the discharge gap 16 mm long, from where a sample can be taken to determine the probability Pstim according to the method of ref. [1]. For the experiments, a technique was developed for introducing the 186mRe isomer into the liner by electrodeposition of a rhenium layer about 0.5 μm thick onto tungsten wires. The mass of rhenium in the liner will be ~ 10 μg. Thus, in the plasma of the Angara-5-1 facility, the amount of the 186mRe isomer can be an order of magnitude higher than in the laser plasma of the experiment [1], and the probability Pstim can be two orders of magnitude higher. All this shows that the proposed experiments at Angara-5-1 facility are promising.References:
1. V.V. Vatulin, N.V. Zhidkov, A.A. Rimskii-Korsakov, V.V. Karasev, V.V. Koltsov, A.I. Kostylev, G.V. Tachaev, Bull. Russ. Acad. Sci.: Phys. 81, 1159 (2017).
2. V.V. Koltsov. “On stimulation of nuclear isomer de-excitation in plasma of electric explosion of conductors”. Proc. Int. Conf. “Nucleus-2018” - 68th Meeting on Nuclear Spectroscopy and Atomic Nucleus Structure. Voronezh, Russia. July 2-5, 127 (2018).
3. G.S. Volkov, V.I. Zaitsev, E.V. Grabovski, M.V. Fedulov, V.V. Aleksandrov, N.I. Lakhtyushko // Plasma Phys. Rep. 36, 191 (2010).Speaker: Vladimir Koltsov (Khlopin Radium Institute) -
50
Plasma shielding effects on nuclear spectra: 18Ne application
In this study, for ?the first time, in particular to astrophysics and fusion studies, how atomic nuclei embedded in the plasma environment are affected by plasma are systematically analysed. The related interactions in plasma environments considered as Debye and quantum plasma are depicted by more general exponential cosine screened Coulomb (MGECSC) potential. The plasma effects on the change of nuclear energy levels are probed through computations performed within the nuclear shell-model framework. For this purpose, the single-particle energy (spe) values to be used in the calculations are obtained by considering the modified Woods-Saxon (WS) potential due to shielding effect of plasma environment. As the modification in question is executed on Coulomb interaction term in WS potential, the computations are carried out for 18Ne nucleus which has two valence protons. Under the influence of the plasma, it is confirmed that the spe's change within certain limit value ranges. When considering the nuclear shell-model for the related computing, it is clear that this change leads to an obvious shifting in the energies of the nuclear states. It is observed that proton spe values are sensitive to Plasma shielding effect, and shielding effect has a significant potent on the ground-state and excited energy states of the nucleus. In particular, the ground-state binding energies are determined to be extremely sensitive to the plasma shielding parameters Plasma environments affect the proton spe and ground state energy (gse) in the same way.
Speaker: Serkan Akkoyun (Cumhuriyet University)
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Poster session (Mixed): Nuclear medicine, study of cultural heritage, plasma physics, neutrino and astrophysicsConvener: Nikita Prokofiev (Saint Petersburg State University, Russia)
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Study of the silvering process of ancient Roman coins using nuclear-physical methods and complementary techniques
Monetary system in ancient time was a challenging task, influenced by economic crisis, availability of metal sources and monetary reforms. In particular, the Ag content of the currency minted for about sixty years by the Antoninii emperors reflected the economic health or crisis of the Roman Empire. At the beginning, the Antoninianus denomination was a silver-rich coin (up to 80% of Ag), but gradually was devalued becoming a bronze coin with a very low content of silver (about 2–3% of Ag).
Two of ancient Roman silver coins (one of them was mint as barbarian imitations of roman coin), dating back between III-IV Centure AD have been characterized. We used a set of modern micro- and non-invasive analytical techniques: Focused Ion Beam-Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray Microanalysis (FIB-FESEM-EDXM), Scanning Electron Microscopy (SEM-EDX), Micro-X-ray Fluorescent analysis (µXRF), Synchrotron- and Neutron-based Computer Tomography (CT), Synchrotron-based X-ray Diffraction (XRD), Neutron Radiation Analysis (NRA) that offers the most advantageous means of obtaining access to the bulk composition and other complementary methods.
The results revealed that a complex Ag-Cu and Ag-Cu-Pb-Sn alloys were used. The use of alloys was common in the flourishing years of the Roman Empire. In the prosperous periods, Romans produced Ag-Cu alloys with relatively high silver content for the manufacture of both the external layers and inner nucleus of coins. This study also revealed that, although surface silvering processes were applied in different periods of crisis under the reign of Antoninii, even during crisis, Romans produced Antoninianus of high quality. It possible, moreover, a first attempt to improve the silvering procedure using Hg-Ag amalgam has been identified, because Hg was detected in the upper silver layer of coins.
Speaker: Dr Evgeny Sozontov (NRC "Kurchatov Institute") -
52
STRONTIUM ISOTOPE EVIDENCES
Abstract-
Four outstanding multiple burials were discovered near Eulau, Germany. The 4,600-year-old graves contained groups of adults and children buried facing each other. Skeletal and artifactual evidence and the simultaneous interment of the individuals suggest the supposed families fell victim to a violent event. In a multidisciplinary approach, archaeological, anthropological, geochemical (radiogenic isotopes), and molecular genetics methods were applied to these unique burials. Using autosomal, mitochondrial, and Y-chromosomal markers, it was identified genetic kinship among the individuals. A direct child-parent relationship was detected in one burial, providing the oldest molecular genetic evidence of a nuclear family. Strontium isotope analyses point to different origins for males and children versus females. It tells insight into a Late Stone Age society, which appears to have been exogamous and patrilocal, and in which genetic kinship seems to be a focal point of social organization.
Cotton (Gossypium sp.), a plant of tropical and sub-tropical origin, appeared at several sites on the Arabian Peninsula at the end of the 1st mill. BCE -beginning of the 1st mill. CE. Its spread into this nonnative, arid environment is emblematic of the trade dynamics that took place at this pivotal point in human history. Due to its geographical location, the Arabian Peninsula is connected to both the Indian and African trading spheres, making it complex to reconstruct the trans-continental trajectories of plant diffusion into and across Arabia in Antiquity. Key questions remain pertaining to: provenance, i.e. are plant remains of local or imported origin and the precise timing of cotton arrival and spread. The ancient site of Mleiha, located in modern-day United Arab Emirates, is a rare and significant case where rich archaeobotanical remains dating to the Late Pre-Islamic period (2nd–3rd c. CE), including cotton seeds and fabrics, have been preserved in a burned-down fortified building. To better understand the initial trade & production of cotton in this region, strontium isotopes of leached, charred cotton remains are used as a powerful tracer and the results indicate that the earliest cotton finds did not originate from the Oman Peninsula, but were more likely sourced from further afield, with the north-western coast of India being an isotopically compatible provenance. Identifying the presence of such imported cotton textiles and seeds in southeastern Arabia is significant as it is representative of the early diffusion of the crop in the region, later to be grown extensively in local oases.Speaker: Mr NARAYAN PRASAD AGARWAL (UNIVERSITY OF CALCUTTA,INDIAN SCIENCE NEWS ASSOCIATION) -
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SIMULATIONS EXAMINE PERFORMANCE OF PURE BORON, BORON CARBIDE, HIGH-DENSITY CARBON AND BORON NITRIDE ABLATORS—THE MATERIAL
Abstract-
The performance of pure boron, boron carbide, high-density carbon and boron nitride ablators—the material that surrounds a fusion fuel and couples with the laser or hohlraum radiation in an experiment—in the polar direct drive exploding pusher (PDXP) platform. The platform uses the polar direct drive configuration to drive high ion temperatures in a room-temperature capsule and has potential applications for plasma physics studies and as a neutron source. Our simulations predict that the platform is not amenable to the electron-ion coupling measurements due to a lack of implosion symmetry, these alternate materials do enable better coupling between the lasers and capsule, we can test those predicted impacts on future neutron source experiments.
Examining the improvement in coupling because it could help improve the yield of the polar direct drive neutron sources, and ultimately provide data on the validity of laser modeling for direct drive simulations. Inertial confinement fusion simulation code developers implement more advanced models for electron-ion coupling, and modeling the direct drive implosions have been closely coupled with that code development. One of the main goals has been to create ignition in deuterium-tritium plasma in the laboratory. The design of these experiments relies heavily on computer models that are based on an understanding and assumptions about the behavior of these hot plasmas. In these experiments, ions are heated more rapidly than the electrons via a very strong laser-generated shock. Intended to use time resolved spectroscopy, which is a measure of how much light is being emitted from the plasma at a specific frequency, in order to measure the temperatures of both the ions and the electrons as a function of time during the experiment. Electron-ion coupling is a parameter that describes how ions and electrons exchange energy in plasma. The PDXP platform was developed to study electron-ion equilibration but ended up being an ideal neutron source for several other campaigns. The great advantage of this platform is that it is simple —spherical shell filled with fuel—and allows multiple diagnostics from any ports to take data and produces high neutron yield. This research did a theoretical study of performance (neutron yield) versus composition of the shell materials and its thickness.Based on these models predicting a particularly useful improvement in performance, like higher yield, or the model predicting a large change in a measured quantity, like the trajectory of the imploding capsule or the temperature of the nuclear burn, we can execute to test if the calculation was indeed successful at predicting the change in performance.Speaker: Mr NARAYAN PRASAD AGARWAL (UNIVERSITY OF CALCUTTA,INDIAN SCIENCE NEWS ASSOCIATION) -
54
ION CHANNELS AND NUCLEAR PORE CHANNEL GATING
Abstract
Calcium, sodium, potassium, zinc, magnesium etc & all other ion channels carry vital biological functions with respective signaling playing great role in plasma, heart beats, dopamine & many other functions either directly by particle, ions or by their waves. There are three main types of ion channels, i.e., voltage-gated, extracellular ligand-gated, and intracellular ligand-gated along with two groups of miscellaneous ion channels. Ion channels facilitate passive movement of ions across biological membranes and are essential for life. Ion-channel engineering approaches help elucidate structure-function mechanisms of proteins. Engineered ion channels are important tools for probing and manipulating cell biology. Voltage-gated channels respond to perturbations in cell membrane potential, and are highly selective for a specific ion, i.e., Na+, K+, Ca2+, and Cl-, Others are Ligand-Gated Ion Channels (LGIC),‘Cys-Loop” LGIC, Ionotropic Glutamate Receptors., P2X Receptors. .Mechano-Sensitive Ion Channels. Their ions &ion channels enable the flow of electrical signals through the body.
Nuclear envelope (NE) cisternal Ca2+ and cytosolic ATP are required for nuclear-pore-complex-(NPC-) mediated transport of DNAs, RNAs, transcription factors and other large molecules. Isolated cardiomyocyte nuclei, capable of macromolecular transport (MMT), have intrinsic NPC ion channel behavior.Ca2+ and IP3 waves may convert the NE into an effective Ca2+ barrier and, consequently, affect the regulation of gene activity and expression through their feedback on MMT and NPCC gating. Thus, [Ca2+] NE regulation by intracellular messengers is an effective mechanism for synchronizing gene activity and expression to the cellular rhythm. We found that calcium ion channels & some other ion channels play great roles in all biological activities & require great investigations in field of nuclear medicines as most of diseases are caused by abnormal functions of ions & ion-channels in lives. Behind biology is physics or nuclear physics & all require simultaneous quite clear definitions in this respect.Speaker: Mr Narayan Prasad Agarwal (Indian Science News Association, University of Calcutta, INDIA.) -
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Generation of radiation effects from high-energy gamma quanta during irradiation of biological objects at the medical linear accelerator ELEKTA AXESSE
The study of X-ray-induced mutations The white gene is becoming one of the main test objects in the study of the problem of direct and reverse mutation of its alleles under the action of X-ray radiation [1], and later under the action of neutrons and γ-radiation [2] on such biological objects as Drosophila melanogaster. Moreover, at present, Drosophila is used as a model object in the study of the influence of various environmental factors, such as high and low temperatures, the inclusion of active oxygen in the metabolism, nutritional characteristics and diabetes mellitus on longevity and fertility [3-4]. The work [5] studied the number and frequency of mutations in the white gene induced by different doses of reactor neutrons (E = 0.85 MeV) with doses from 2.5 Gy to 20 Gy, as well as by 60-Co γ-radiation with doses up to 60 Gy. In various works, gamma-ray irradiation of the studied biological objects is mainly carried out with energies up to 3 MeV. In this work, experiments have been carried out to study mutations of the radiation effect on the capabilities of new generations of Drosophila melanogaster by beams of gamma quanta with energies of 10 and 15 MeV. The radiation doses were 2 Gy, 10 Gy and 20 Gy. The electron accelerator Elekta Axesse of the Sunkar Cancer Center (Almaty, Republic of Kazakhstan) was used as a source of gamma quanta. The technique of irradiation of biological objects was tested by measuring the experimental linear absorption coefficients of 6 MeV gamma quanta obtained at this linear accelerator for elements B, C, O, S, Fe, Ba [6].
As a result of the experiments, the types of induced mutations, the dependence of the mutagenic effect on the dose were determined, and the significance of genetic effects for various energies of gamma quanta was estimated. This made it possible to develop a methodology and perform experiments on irradiation of Drosophila melanogaster to study the influence of hard gamma radiation and the occurrence of radiation effects and mutations in this energy range.
This research has been funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP09258978).- A. Pastink et al. Mutat. Res. 177 (1987)
- I.D. Alexandrov. Mutat. Res. 127 (1984)
- L. Arquier et al. Archives of Cardiovascular Diseases Supplements 13(2), (2021)
- L.P. Zakharenko et al. Insects 12, (2021)
- E.V. Kravchenko et al. Radiation biology. Radioecology 59(5), (2019)
- T.M. Gladkikh et al. 9th International Scientific Conference. Almaty (2016)
Speaker: Mirgul Bigeldiyeva (al-Farabi Kazakh National University) -
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Influence of high-energy proton and gamma-radiation on DNA structure in solution
The use of a specific technique and type of radiation in radiotherapy of tumors is determined by various factors: the localization of the tumor in the body, its oxygenation, the stage of the disease, the availability of the technique for the patient, etc. The study of damage in the DNA structure under the influence of different types of radiation and with varying irradiation conditions provide important information for improving the methods of radiation therapy. This work compares the damage in the DNA structure under the action of ${}^{60}Co$ $\gamma$-radiation (used in the gamma knife therapeutic device) and 1 GeV protons (at synchrocyclotron of the St. Petersburg Institute of Nuclear Physics Research Center "Kurchatov Institute" SC-1000, since 1975 there has been a medical center for stereotactic proton therapy). These two types of radiation have the same value of LET = 0.3 keV/$\mu m$.
Disturbances in the DNA structure were studied by spectrophotometric melting. The parameters of the helix-coil transition in the irradiated macromolecule are influenced by various types of radiation damage. Single- and double-strand breaks, destruction, modification, and release of nucleobases lead to destabilization of the secondary structure and lower the melting temperature of DNA (Tm), while interstrand cross-links increase Tm [1].
Melting curves of DNA irradiated with doses of 0-100 Gy were obtained at ionic strengths of solutions of 5 mM and 150 mM $NaCl$, as well as at a total ionic strength of 5 mM = 3 mM $Na^+$ + 2 mM $Mg^{2+}$. The absorption spectra of DNA solutions were measured at $25^oC$, $95^oC$, as well as after melting and rapid (within 10 min) cooling to $25^oC$. From these data, the helix-coil transition interval, Tm, the DNA molar extinction coefficient, the hyperchromic effect, and the degree of DNA renaturation after melting upon rapid cooling were determined. Proton and $\gamma$-irradiation cause a broadening of the melting interval, which indicates an increase in the heterogeneity of the DNA structure, i.e. the appearance in the DNA chain of regions that differ sufficiently in thermal stability. For DNA irradiated in 150 mM $NaCl$ solutions with proton and $\gamma$-radiation, several maxima are observed in the differential melting curves. Under these conditions, it is possible to assume the formation of cross-links (both between two complementary strands and between DNA regions distant along the chain) as a result of irradiation. In 0.15M $NaCl$ solutions, the secondary structure of DNA is more resistant to radiation than in 5mM $NaCl$ solutions. It was found that proton irradiation causes a smaller drop in DNA Tm than $\gamma$-irradiation in a 0.15M $NaCl$ solution at doses of 0–100 Gy and in a 5 mM $NaCl$ solution at doses of 70-100 Gy. For the DNA irradiated with protons at doses of 10 and 20 Gy, an abnormally large hyperchromic effect was recorded, exceeding the value measured for native DNA. The data obtained allow us to conclude that under proton irradiation, clustered damage are formed in the DNA structure -- slowly repairable or unrepairable sites, while under $\gamma$-irradiation, isolated DNA lesions appear, which can be quickly and efficiently repaired in the cell [2]. Thus, irradiation with high-energy protons has a greater lethal effect on the cell than $\gamma$-irradiation.
References
1. C.R.Cantor, P.R. Schimmel. Biophysical Chemistry. Part 2,3. W. H. Freeman and
Company, San Francisco (1980).
2. E.Sage, N.Shikazono, Free Radical Biology and Medicine 107, 125 (2017).Speaker: Sofia Paston (St.Petersburg State University) -
57
Investigation of the effect of fixation devices on dose delivery in radiation therapy of head tumors.
The main goal of radiation therapy is to irradiate the target with a given dose while maximizing the protection of healthy tissues and organs. According to the theoretical data from radiobiology and the ICRU recommendations, to achieve the maximum results of radiation therapy, dose delivery with an accuracy of 3-5% is required [1]. The dosimetric effect of devices external to the patient is a complex combination: an increase in the dose to the skin, a decrease in the dose in a tumor, and a change in the dose distribution [2]. Despite the fact that the use of dosimetry protocols (TRS-398, TRS-483) and modern dose calculation algorithms can significantly reduce the uncertainty in dose delivery, the presence of immobilization devices is usually overlooked in treatment planning.
We studied the effect of immobilization devices on the dose in the skin layer and the average dose in the target during RT of head tumors. In the Eclipse treatment planning system, VMAT irradiation of target (ball of radius R = 3 cm) was simulated in the CIRS STEEV patient's head phantom with the inclusion of the following Q-fix fixation devices in the phantom model: headrest, thermoplastic mask (U-shaped mask support, thermoplastic part of the mask ), base plate ACCUFIX. The PTW 3D Semiflex ionization chamber (measuring volume 0.07 cm3) for measuring the average dose in the target was positioned in the geometric center of the target. Parameters such as the speed of the accelerator gantry, the speed of movement of the multi-leaf collimator blades and their position, dose rate and beam energy remained unchanged for all dosimetric irradiation plans. The therapeutic table was taken into account in all cases; when analyzing the irradiation plans, the dose distributions were normalized to 1. The experiment on measuring the average dose in the volume of the ionization chamber was carried out on a linear medical accelerator TRUEBEAM (Varian).
The simulation results showed that the failure to take into account fixing devices in dosimetric planning (not including fixing devices in the patient model) can lead to an underestimation of the average, maximum, minimum dose in the target and target coverage by 1.3%, 0.8%, 1.4 % and 1.3%, respectively. The use of a 1.6 mm U-shaped thermoplastic Q-fix mask as a fixing device increases the dose in the cutaneous 1.1% (the thickness of the skin layer according to the recommendations of RTOG 1021 [3] is a layer of 5 mm from the edge of the phantom). The simulation results are in good agreement (less than 0.2%(+-0.03%) discrepancy) with the measurements of the average dose in the target. The results obtained show the need to take into account the immobilization device when planning radiation therapy, since the errors caused by their absence in the model are comparable to the allowable limits.
This research has been supported by the Interdisciplinary Scientific and Educational School of Moscow University «Photonic and Quantum technologies. Digital medicine»- B.J. Mijnheer et. al., What degree of accuracy is required and can be achieved in photon and neutron therapy?, Radiother. Oncol. 8, 237– 252 (1987).
- A.J. Olch et. al., Dosimetric effects caused by couch tops and immobilization devices: Report of AAPM Task Group 176 (2014)
- C.F. Hiran et. al., Clinical Research Protocol RTOG 1021 (2013).
Speaker: Mr Georgii Smirnov (Faculty of Physics, Lomonosov Moscow State University) -
58
Simulation of Prompt Gamma Imaging in Hadron Therapy
Hadron therapy is efficient method of cancer treatment due to phenomenon of the Bragg peak which cause precise localization of the dose absorbed by biological tissues [1, 2]. It improves quality of life of a patient minimizing action of therapeutic beam on healthy part of body. Transversal scattering of the beam is less than that for other kinds of radiotherapy.
Hadron therapy has some shortcomings. It is highly sensitive to unavoidable errors of preparing the treatment plan and its realization. Influence of some kinds of errors or uncertainties cannot be accounted in simulation or theoretic considerations. So experimental or "online" techniques are absolutely required to control the hadron therapy treatment process and especially stopping region of protons or carbon ions from the therapeutic beam [3]. Positron emission and computer tomography methods may be used to control the treatment process. Prompt Gamma Imaging (PGI) method is relatively new and perspective technique, which may be very efficient. Our study consider dependence of the beam parameter, Bragg peak localization and distribution parameters of secondary particles in the PGI method. Reference points of distribution are defined which may be used to define Bragg peak position. Proton and carbon ions have been considered. FLUKA and GEANT4 packages are used for simulation.
Bibliography
1. R.R. Wilson., Radiology 47, p.487, (1946).
2. Radhe Mohan, David Grosshans., Advanced Drug Delivery Reviews 109, p.26 (2017).
3. Antje-Christin Knopf, Antony Lomax., Phys. Med. Biol. 58, p.131 (2013).Speaker: Sergei Nemnyugin (Saint Petersburg State University) -
59
THE LEVEL OF THE URANIUM, RADIUM, AND OTHERS RADIONUCLIDES CONCENTRATION IN OBJECTS OF ENVIRONMENT AND BIOOBJECTS IN POWERFUL INDUSTRIAL CENTER
The problem of actinides and radionuclides migration, distribution, and concentration process in objects of environment and bioobjects stay of one of the importance and actual. There are the samples of drinking water, soil, roots, and the leaf of hydrophyte “Pistia stratiotes”, the teeth of patients (72) with odontogenic inflammatory diseases, and patients' kidney stones (54) with urolithiasis treated. The samples were taken from Kharkiv`s region. The determination of actinides and radionuclides content in samples was performed by gamma spectrometer method on Ge(Li)-detector with the volume of 50 cubic cm and resolution of 3.2 keV at 1332 keV line. To reduce the influence of background the detector is equipped with three-layer Pb-Cu-Al protection. Samples irradiated by bremsstrahlung from the linear accelerator electron with energy 23 MeV and current 500 micro A. Activation of samples carried out on air, the temperature of samples in the course of the activation didn’t exceed 40 degrees C. The more significant error is for 238U (line 186 keV is equal sums of the line from 226Ra + 235U). The errors of measurements were from 7 to 25%. The limit of detection elements for photoactivation analysis was 100-0.1 ppm. The 235U and 226Ra in the nuclear reaction were calculated with help of the program complex PENELOPA. In addition to gamma activation analysis, there was the method of IR-spectroscopy (the spectral range 4000…400 cm-1 regions) and crystal-optical investigation for determination of different chemical components, crystalline form, classification kidney stones, etc. in biological samples.
The whole samples contained 235,238U and 226Ra. In drinking water, there are these actinides 1.2 - 1.8 ppm Bk/cubic dm. The actinides content in various types of soil has differences. There are radionuclides content in hydrophyte 40K, 131I, 7Be, 228Ac, 212,214Pb, 137Cs, 235U, 226Ra. It has been found that the accumulation of 226Ra, 212,214Pb, 214Bi in the teeth with odontogenic pathology is 15…40 times higher than in the teeth of patients with the same pathology in other countries. For the samples of teeth and kidney stones, 235U content was from 1 to 100 ppb.
The detected actinides and radionuclides confirm the influence of technogenic pollution of the ecosystem, as well as their geochemical mobility and biogenic migration.Speaker: Mikola Dykyi (Head of department) -
60
Topology of distribution of natural radioactivity on the surface of the human body
The main share of oncological diseases of the lungs and bronchi is caused by radon isotopes and their daughter decay products [1], therefore, the study of radiation damage to biological objects from radon isotopes 219Rn, 220Rn, 222Rn and their decay products is an urgent task. In Kazakhstan, lung cancer is in second place (10.4%) among oncological diseases.
The aim of this work was to study the distribution of natural alpha, gamma and beta background over the surface of the human body as an indicator of cancer risk and cancer incidence. A method of measuring the topology of distribution over biological objects and the human body of local zones of background radiation using modern electronic radiometers was developed: RKS-01A-SOLO, RKS-01B-SOLO and RKS-01G-SOLO. The distribution of alpha, gamma, and beta activity over the human body was measured in a room with the lowest background by scanning along and across the body at the closest possible distance from it. Measurements were taken at the following control points: head-4, thyroid-3, left-1.9 and right side of the chest-2.1, stomach-1 and legs-0.
According to the results (Figure 1) of measurements of the radioactivity of the control points of the human body, it can be seen that the greatest background is found in the region of the thyroid gland and in the region of the brain. These results confirm the previously known facts [2] that the accumulation of radioactivity in the human body is concentrated in adipose tissues, as well as in muscle tissue accumulations. The well-known pattern of an increase in the natural radiation background with the age of a person is associated with the effect of accumulation of radioactivity due to long-lived radionuclides. The same pattern in medicine is diagnosed as an increase in diseases in the corresponding localizations. This pattern will be investigated in the future in the pool of age categories of the population due to the fact that the risk of cancer morbidity increases with age, as well as in cancer patients in the corresponding medical institutions.
This research is funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP09058404).- 2012 IARC Monographs on the Evaluation of Carcinogenic Risks to Humans // IARC. – Vol. 100D Radiation. – 2012. – ISBN 978 92 832 1321 5.
- Beckman I.N. Radiochemistry. Vol. 1. – Moscow: Yurayt Publishing House, 2020. – 473 p.
Speaker: Yuliya Zaripova (al-Farabi Kazakh National University) -
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Precision measurements of $^{144}$Ce - $^{144}$Pr beta-spectra with Si(Li)-spectrometer
A.V. Derbin, I.S. Drachnev, A.M. Kuzmichev, I.S. Lomskaya, M.S. Mikulich, V.N. Muratova, N.V. Niyazova, D.A. Semenov, M.V. Trushin, E.V. Unzhakov
Petersburg Nuclear Physics Institute National Research Center Kurchatov Institute
The discovery of solar and atmospheric neutrino oscillations means that at least two of three neutrino mass states are nonzero. The oscillation parameters and the Planck telescopeconstraints on the sum of light neutrinomasses limit the most severe mass state of the three known types of neutrinos ($\nu_e, \nu_\mu, \nu_\tau$) to 70MeV. Heavier sterile neutrinos appear in many SM extensions, they are well-motivated candidates for the role of dark matter particles. This work is devoted to the search for manifestations of massive neutrinos in the $\beta$-spectra of $^{144}\rm{Ce}$ – $^{144}\rm{Pr}$ nuclei. The $^{144}\rm{Ce}$ – $^{144}\rm{Pr}$ electron antineutrino source is one of the most suitable for studying neutrino oscillations into a sterile state with a mass of about 1 eV. The $^{144}\rm{Ce}$ – $^{144}\rm{Pr}$ decay schemes allow to test the emission of neutrinos with masses from several keV to 3 MeV. The range of possible investigated masses is determined by the resolution of the β-spectrometer and the end-point energy of $^{144}\rm{Pr} \beta$-decay [1].
We used an original $\beta$-spectrometer with 4$\pi$-geometry [2], consisting of two Si(Li) -detectors with a sensitive volume thickness 8 mm, that exceeds the range of 3 MeV electrons. The 4$\pi \beta$ total absorption spectrometer allows direct measurement of $\beta$-spectra, which does not require corrections of the response function due to backscattering of electrons from the surface of the crystal. The measured spectrum, containing $1.5 \times 10^9$ events, was fitted in the energy range (250 - 3030) keV. The upper limits on the mixing parameter $|U_{eH}|^2$ were determined in a standard way from the profile of the dependence $\chi^2 (|U_{eH}|^2)$. As a result, for neutrinos with a mass $m_{\nu H}$ in the range (100–2200) keV, new upper limits were set at the level $|U_{eH}|^2 \leq (0.1 −3.0) \times 10^{−3}$ for $90\%$ C.L., which are 2-3 times more stringent than those obtained in previous experiments.
The work was supported by the Russian Science Foundation: grant RFBR pos. 19-02- 00097 and grant RSF pos. 20-02-00571.Bibliography
1. A.V. Derbin, I.S. Drachnev, I.S. Lomskaya, V.N. Muratova et al., Search for neutrinos with mass (0.01–1.0) MeV in $\beta$-decays of $^{144}\rm{Ce}$ – $^{144}\rm{Pr}$nuclei, JETP Letters, 2018, vol. 108, p. 531
2. Alekseev I.E., Bakhlanov S.V., Derbin A.V., Drachnev et al., A Silicon 4π Spectrometer of β-Decay Electrons with Energies of up to 3 MeV, Instrum. Exp. Tech. 64 (2021) 2, 190-194Speaker: Prof. Alexander Derbin (Petersburg Nuclear Physics Institute NRC KI) -
62
Sensitivity of r-process simulation to choice of the mass model
Astrophysical r-process is considered to be the main source of neutron-rich isotopes beyond the iron peak and, therefore, poses a great interest to modern nuclear physics. It takes place in stellar medium at temperatures above 1 GK and very high densities that can be reached in extreme scenarios,such as supernova explosions or neutron star and black hole collisions. Computer simulations of the r-process depend on a very large number of nuclear parameters.
In this study we have calculated r-process nucleosynthesis using numeric model [1], based on the SkyNet library [2], and obtained final mass distributions of r-process products at the temperature of 1.2 GK. One of the most important parameters that impacts neutron capture rates in r-process are masses of participating nuclei, especially in the little-studied exotic isotope regions of the nuclide chart. Sensitivity of the calculation to different nuclear mass models has been studied by substitution of complete astrophysical neutron capture rate libraries, that were used during the calculation. Several reaction rate libraries with different parameters were obtained via TALYS package [3] and their results were compared to each other in the interval $A = 60 ÷ 220$.
Calculations were performed using the macro-microscopic models FRDM [4] and WS4 [6], the Skyrme interaction-based HFB mass model [5], and the new mass evaluation based on local mass relations [7]. Calculated r-process yields illustrate the differences of the considered mass models.
References:
[1] Negrebetskiy V.V., Stopani K.A., Moscow Univ. Phys. Bull. 76, 22 (2021).
[2] Lippuner J., Roberts L.F., ApJS 1, 233 (2017).
[3] Koning A.J., Rochman D. et al., Nucl. D. Sheets 1, 155 (2019).
[4] Möller P., Nix J.R. et al., ADNDT 59, 185 (1995).
[5] Goriely S., Chamel N., Pearson J.M., Phys. Rev. Lett. 102, 152503 (2017).
[6] Na-Na Ma, Hai-Fei Zhang et al. 2019 Chinese Phys. C 43, 044105 (2019).
[7] Vladimirova E.V., Simonov M.V., Tretyakova T.Yu., Proceedings of AYSS-2020, Dubna, Russia, 9-13 Nov. 2020 (in print)Speaker: Vasily Negrebetskiy (Lomonosov Moscow State University)
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PlenaryConvener: Yury Novikov (Petersburg Nuclear Physics Institute of ‘Kurchatov Research Center’)
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63
Detection of sterile neutrinos in the Neutrino-4 experiment, comparison with the results of other experiments and the 3 + 1 neutrino model
The results of measurements of the dependences of the flux of reactor antineutrinos and their spectrum on the distance to the center of the active zone of the SM-3 reactor (Dimitrovgrad, Russia) in the range of 6 12 meters are presented. We observe the effect of oscillations at a confidence level of $3 \sigma$ in the vicinity of the parameter values $\Delta m_{14}^{2}=\left(7.3 \pm 0.13_{s t} \pm 1.16_{\text {syst}}\right)$ eV$^{2}$ and $\sin^{2} 2 \theta=0.36 \pm 0.12_{\text {stat}}$ $(2.9 \sigma)$. The paper presents a comparison of this result with the results of other experiments on the search for sterile neutrinos. Combining the results of the Neutrino-4 experiment with the results of gallium and reactor anomalies, we obtained the value $\sin ^{2} 2 \theta_{14} \approx 0.19 \pm 0.04(4.6 \sigma) .$ The results of the Neutrino- 4 experiment are compared with the results of other reactor experiments NEOS, DANSS, STEREO, PROSPECT and with the results of the accelerator experiments MiniBooNE, LSND and with the results of the IceCube experiment. An analysis of the results within the framework of the $3+1$ neutrino model is presented. The mass of sterile neutrinos from the Neutrino-4 experiment (assuming that $\left.m_{4}^{2} \approx \Delta m_{14}^{2}\right)$ is $m_{4}=2.68 \pm 0.13 \mathrm{eV}$. Using estimates of mixing angles from other experiments, the following masses for electron neutrinos, muon neutrinos, and tau neutrinos can be calculated: $m_{\beta}=(0.58 \pm 0.09) \text{eV}$, $m_{\mu}=0.42 \pm 0.24 \mathrm{eV}, m_{\tau} \leq 0.65 \text{eV}$. The PMNS matrix for four states together with sterile neutrinos is presented, as well as a scheme for mixing neutrino flavors with sterile neutrinos for direct and inverse mass hierarchies.
References:
1. Serebrov A.P. et al. Experiment Neutrino-4 search for sterile neutrino and results of measurements Phys. Rev. D in press, arXiv:2005.05301
2. Serebrov A.P., Samoilov R.M. Analysis of the Results of the Neutrino-4 Experiment on the Search for the Sterile Neutrino and Comparison with Results of Other Experiments. JETP Lett. 112, 199–212 (2020). arXiv:2003.03199 https://doi.org/10.1134/S0021364020160122 .Speaker: A.P. Serebrov (NRC "KI" Petersburg Institute of Nuclear Physics, Gatchina, Russia) -
64
Status and physics potential of JUNO
The Jiangmen Underground Neutrino Observatory (JUNO) is a neutrino experiment under construction in a 700 m deep underground laboratory near Jiangmen in South China. The main neutrino target will consist of 20 kton of liquid scintillator held in a spherical acrylic vessel. The experiment is designed for the determination of the neutrino mass ordering, one of the key open questions in neutrino physics. This measurement will be done by studying the fine spectral structure of reactor antineutrino vacuum oscillations at a baseline of 53 km, requiring an unprecedented energy resolution of 3% at 1 MeV. The light produced by the scintillator will be seen by about 20,000 large PMTs (20”) and about 25,000 small PMTs (3”). The OSIRIS detector will monitor the radio-purity of the liquid scintillator during the months-long filling of the main detector, while the unoscillated spectrum from one reactor core is planned to be closely monitored by the Taishan Antineutrino Observatory (TAO). JUNO will also significantly improve the precision of already measured neutrino oscillation parameters. Astrophysical measurements of solar, geo, supernova, DSNB, atmospheric neutrinos, as well as searches for proton decay or dark matter are also a part of the vast physics programme. The presentation will review the physics goals, design, as well as the status of the JUNO project.
Speaker: Dr Yury Malyshkin (Joint Institute for Nuclear Research) -
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Baikal-GVD neutrino telescope: status and first results
The Baikal Gigaton Volume Detector (Baikal-GVD) is the km$^3$-scale
underwater neutrino telescope designed for the study of high-energy
astrophysical neutrino flux. The Baikal-GVD sensitivity range extends from 100 GeV to multi-PeV neutrinos and beyond. The telescope is being
in its construction phase and presently consists of 64 strings
carrying 2304 optical sensors providing an effective volume for
high-energy cascade detection of 0.4 km$^3$. An overview of the detector
construction, the status and prospects of the detector deployment and
of the first results from partially built telescope is given in this
talk.Speaker: Dr Grigory Safronov (INR RAS) -
10:45 AM
Coffee break
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First experimental proof of CNO fusion cycle in Sun with the Borexino Experiment
Borexino, an ultra-pure liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso in Italy, has detected solar neutrinos from the CNO fusion cycle for the first time in history. The CNO cycle is predicted to be the dominant energy production process in massive stars, while it is a secondary mechanism for the solar energy production. Its small associated neutrino flux, as well as the similarity of the spectral shapes of electrons scattered off CNO and pep solar neutrinos and electrons from the decays of $^{210}$Bi background, make measurement of CNO solar neutrinos very challenging. The proof of the existence of CNO fusion process in Nature has been made possible by carrying out several campaigns of purification of Borexino liquid scintillator and in 2016, thermal stabilization of the detector. This talk, on the behalf of the Borexino collaboration, will present the overview of the challenges along with their solutions adopted to extract the CNO solar neutrino signal with the rejection of the null hypothesis with greater than 5sigma significance at 99% C.L as well as the implications of this result for solar physics.
Speaker: Ms Apeksha Singhal (Forschungszentrum Jülich - IKP-2) -
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KATRIN: current status of project and result on the neutrino mass.
N.A. Titov INR RAS (for the KATRIN collaboration)
The KArlsruhe TRItium Neutrino experiment (KATRIN) is designed to improve the existed direct limit on the effective electron antineutrino mass by an order of magnitude, with a projected sensitivity of 0.2 eV/c2 at the 90% confidence level. To achieve this KATRIN is using a windowless gaseous molecular tritium source containing up to 100 GBq activity and electrostatic spectrometer with adiabatic magnetic collimation with resolution at 1 eV level.
At May,2021 five data taking runs (with duration about two month each) are completed. First two runs are analyzed and provide new neutrino mass limit mν < 0.8 eV/c2. First data run is analyzed for the presence of light sterile neutrino signal. With current level of sensitivity KATRIN data can’t neither confirm nor exclude Neutrino-4 experiment claim of observed sterile neutrino signal. Currently, the main efforts of the KATIN team are aimed at reducing the spectrometer background and achieving stable data collection parameters.. In the historical introduction are considered main milestones of neutrino mass search, particularly contribution of Leningrad - St.Petersburg physicists.Speaker: Nikita Titov -
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Recent results from IceCube
IceCube neutrino observatory is 1km3 detector located at the South Pole in Antarctica. Its construction with was completed in 2010. Since then it has continuously collected data: cosmic rays with IceTop, cosmic rays induced muons with in-ice arrays, low energy atmospheric neutrinos with Deep Core, and high energy atmospheric and astrophysical neutrinos with IceCube. The unexpectedly large astrophysical diffuse neutrino flux has been discovered by IceCube in 2013. Its spectrum has been characterized with all-flavor neutrino events starting in the detector, muon neutrino induced tracks as well as cascades events, which are dominated by electron and tau neutrino flavors. The energy spectrum is well described by a single power law with a spectral index of 2.5. The origin of astrophysical diffuse neutrino flux remains largely unknown. Data samples utilizing various event topologies have been used to search for astrophysical point sources. So far, IceCube has found an evidence of astrophysical neutrinos originating from two point sources, the TXS 0506+056 blazar and from the NG 1068 active galaxy. High statistics of atmospheric neutrinos collected with the DeepCore array are used for neutrino oscillation analyses and for searches of sterile neutrinos. In this talk we will present most recent physics results from IceCube with astrophysical and atmospheric neutrinos as well as cosmic ray results with IceTop.
Speaker: Joanna Kiryluk (Stony Brook University)
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12:50 PM
Lunch break
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Section 1. Experimental and theoretical studies of the properties of atomic nucleiConvener: Dmitrii Nesterov (St Petersburg State University (RU))
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SELF-CONSISTENT STUDY OF NUCLEAR CHARGE RADII IN Ca REGION
I.N. Borzov 1,2, S.V. Tolokonnikov1,3
1 National Research Centre “Kurchatov Institute”, Moscow, Russia
2Bogolubov Laboratory of Theoretical Physics, Joint Institute of Nuclear Research, Dubna, Russia
3 Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia†E-mail: Borzov_IN@nrcki.ru, cc: ibor48@mail.ru
Fully self-consistent study of the charge radii in the long chains of the Ar to Sc isotopes is presented. The neutron-deficient and neutron-rich nuclei with pairing in both neutron and proton sectors, as well as the (semi-) magic nuclei around the closed neutron shells at N=20, 28, 32 are treated within the Energy Density Functional (EDF) approach with the Fayans functional DF3-a [1]. A comparison with its new options is done, namely Fy(stand) and more recent Fy(∆r,HFB) [2].
The performance of the DF3-a is analysed in describing both absolute radii and OES effects found in the CERN-ISOLDE experiments for 36-52Ca [3] and 36-52K [4] isotopes (Figs.1,2). In addition to a large-scale parametric fitting of the Fayans EDF suggested in [2], a new physics related to a higher power density gradient terms in its surface and pairing parts is of importance. A self-consistent account for the A-dependent fluctuating contribution due to the quasiparticle-phonon coupling explained strong increase of the radii at N>28 in Ca isotopes [5]. It is expected to be responsible for observed local anomalies in isotopic dependence of the absolute radii [3,4].
Supported by the grant of Russian Scientific Foundation (RSF 21-12-00061).Fig. 1. The charge radii of K, Ca, Sc isotopes calculated within the DF3-а functional compared to the data [3,4] and calculations[5 ]. For Ca isotopes, the DF3-a calculation with phonon corrections is shown.
Fig. 2. The charge radii of K isotopes calculated within the DF3-a functional with the gradient paring term compared to the data [3,4].- S.V. Tolokonnikov, E.E. Saperstein, Phys. At. Nucl. 74, 1277 (2011).
- P.-G. Reinhard, W. Nazarewicz, Phys. Rev. C95, 064328 (2017).
- A.J. Miller et.al. Nature Physics, vol.15, 432 (2019).
- A.Koszorus et.al. Nature Physics, https://doi.org/10.1038/s41567-020-01136-5 (2020).
- E.E. Saperstein, I.N. Borzov, S.V. Tolokonnikov, JETP Letters,
Speaker: Ivan Borzov (NRC KI) -
70
First calculation of the $\gamma\gamma$-decay width of a nuclear $2_1^+$ state: The case of $^{48}$Ca
In Ref. [1], the $\gamma\gamma$-decay of a nuclear transition in competition with an allowed $\gamma$-decay has been discovered. This is the observation of the $\gamma\gamma$-decay of the first excited $J^{\pi}=11/2^{-}$ state of $^{137}$Ba directly competing with an allowed $\gamma$-decay to the $J^{\pi}=3/2^{+}$ ground state.The branching ratio of the competitive $\gamma\gamma$-decay of the $11/2^{-}$ isomer of the odd-even nucleus $^{137}$Ba to the ground state relative to its single $\gamma$-decay was determined to be $(2.05\pm0.37)\times10^{-6}$. This discovery has very recently been confirmed and the data were made more precise, in particular with respect to the contributing multipolarities [2].
The competitive double-$\gamma$ decay of the $2_1^+$ state of an even-even spherical nucleus is studied for the first time. The coupling between one-, two- and three-phonon terms in the wave functions of excited states is taken into account within the microscopic model based on the Skyrme energy density functional. The approach enables one to perform the calculations in very large configurational spaces [3,4]. We estimate the generalized electric dipole polarizabilities involved in the $\gamma\gamma/\gamma$ decay process and make a prediction for the branching ratio of the competitive $\gamma\gamma$-decay relative to its single $\gamma$-decay calculated to be $3\times10^{-8}$ for the case of $^{48}$Ca [5].-
C. Walz, H. Scheit, N. Pietralla, T. Aumann, R. Lefol, and V. Yu. Ponomarev, Nature 526, 406 (2015).
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P.-A. S$\ddot{o}$derstr$\ddot{o}$m et al., Nature Commun. 11, 3242 (2020).
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Nguyen Van Giai, Ch. Stoyanov, and V. V. Voronov, Phys. Rev. C 57, 1204 (1998).
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A. P. Severyukhin, V. V. Voronov, and Nguyen Van Giai, Eur. Phys. J. A 22, 397 (2004).
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A. P. Severyukhin, N. N. Arsenyev, N. Pietralla, in preparation.
Speaker: Alexey Severyukhin (JINR) -
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71
Experimental study of halo in isobar-analog states
One of the most striking discoveries in nuclear physics made at the end of the last century was the discovery of the neutron halo in the ground states of some light nuclei located near the neutron stability boundary.
The discovery of the halo led to a revision of many existing ideas in nuclear physics. The purpose of this research is to search and study halo in isobar - analog states of light nuclei. The study of states with a halo in isobar analogs allows one to investigate the manifestation of isotopic invariance at new objects and to relate the properties of the neutron and proton halo. The question of the existence of halo in isobar - analog states has so far not been practically raised in the experimental plan.
The proposed approach is based on measuring the radii of states in which the halo exists or can exist. Its first application made it possible to determine the proton halo in an unbound state of $^{13}$N. Isobaric invariance leads to the fact that the states of two neighboring nuclei obtained by replacing a neutron with a proton are analogous, i.e. have in the first approximation the same structure. In the case of isobar analogs having a halo, the situation is more complicated, since such a change leads to a change in the thresholds that determine the very fact of the appearance of the halo. The data on the radii can give new information for solving the long-standing problem of a single description of the halo in both parts of the spectrum - discrete and continuous. It is proposed to solve problem: Experimentally determine the radii of a number of states in which there can be a halo in nuclei from $^{6}$Li to $^{14}$O, forming isobar - analog doublets and triplets.
We have discovered new possible candidates for a halo in the isobar-analog multiplets A = 12 and A = 14. Signs of a halo were found for the 2$^-$ and 1$^-$ states in the A = 12 multiplet members: 1.19 and 1.80 MeV in $^{12}$B, 16.57 MeV and 17.23 MeV in $^{12}$C and 1.67 and 2.62 MeV in $^{12}$N. In the multiplet A = 14, the 1$^–$ 8.06 MeV state in $^{14}$N turned out to be a candidate for the halo. It should be noted that this is a rather nontrivial result. First, most of the states lie in the continuous spectrum. Secondly, the results were obtained within the framework of two independent methods: ANC (method of asymptotic normalization coefficients) and MDM method (Modified diffraction model). A great achievement was the development of the ANC method for studying resonance states, which made it possible to identify new cases of a proton halo in isobaric analog states. The research results correspond to the world level.Speaker: Alla Demyanova (NRC Kurchatov Institute) -
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SINGLE-PARTICLE ASYMPTOTIC NORMALIZATION COEFFCIENTS IN MIRROR MEDIUM-MASS NUCLEI
The asymptotic normalization coefficients (ANCs) show how likely nucleons can stay in classically forbidden region and their knowledge if important for studying peripheral reactions such as proton capture in stellar environments.
We investigate relations between neutron, $C_n$, and proton, $C_p$, ANCs in mirror nuclear states for medium-mass nuclei, 40 ≤ A ≤ 100, using a two-body potential model with local and nonlocal nucleon-core interactions. Assuming that nuclear potential wells in mirror states are the same, we calculate ratios $R_b = (C_p/C_n)^2$ and compare them to predictions of model-independent analytical formula (7) from [1]. We found that despite increasing strength of the Coulomb interaction with nuclear mass this formula has an accuracy similar to that found in earlier investigations for light nuclei. The analytical formula works better for nonlocal than for local potentials, with the accuracy on most cases within 5%.Fig. 1. Ratio $R_b$ in terms of analytic estimate $R_0$ as a function of proton separation energy $S_p$ for different orbital momentum of removed nucleon, calculated in local (left panel) and nonlocal (right panel) models. The spread of $R_b$ reflects different choice of nucleon-core potentials.
The study is extended to bound-unbound mirror pairs by assessing relations between $C_n$ and the width $\Gamma_p$ of a mirror proton resonance. The deviation of the calculated ratio $\Gamma_p/C_n^2$ from prediction of analytical formula (see expression (8) in [1]) is similar to that obtained for bound-bound mirror pairs. The knowledge of the ratio $\Gamma_p/C_n^2$ can be used to determine widths of narrow proton resonances of astrophysical importance by measuring ANCs of mirror neutron states in peripheral transfer reactions.
1. N. K. Timofeyuk et al., Phys. Rev. Lett. 91, 232501 (2003).Speaker: Olga Sukhareva (Omsk State Technical University) -
3:30 PM
Coffee break
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Pairing and (9/2)n configuration in the neutron-rich Ni isotopes
Neutron-rich nickel isotopes in vicinity of $^{78}Ni$ present an excellent opportunity to study the way in which neutron excess affects the properties of nuclear shell structure. Studies in this region of isotopes also provide insight in the nuclear mechanism of r-process responsible for their synthesis. The path of the consequent reactions constituting r-process is dictated by the shell structure of nuclei far from stability.
As experimental investigations kept advancing and a wealth of new spectroscopic information in various nickel isotopes was obtained, in particular, at the RIBF facility operated by RIKEN Nishina Center in Tokyo [1], the number of variants of their model description is growing, primarily the shell model approach. Neutron-rich $^{70-76}Ni$ are of particular interest due to the significantly different scheme of low-lying states and the $E2$ decay pattern in comparison with other $g_{9/2}$ nuclei, for example, $^{94}Ru$ and $^{96}Pd$ [2]. The new data in these isotopes may allow to test the conservation of seniority, the quantum number referring to the number of nucleons not coupled with total angular momentum $J = 0$. Seniority as a good quantum number can shed light on the properties of excited states such as their modes of decay.
We study the spectra of neutron-rich nickel isotopes $^{70-76}Ni$. To this end, pairing forces in form of surface delta interaction are employed to account for formation of the ground state multiplet (GSM) with seniority $ν = 2$ states. GSM splitting is described with mass relations or masses of neighbouring nuclei. Subsequently, seniority model is used to reproduce or predict the states $ν = 3$ in odd-odd isotopes and $ν = 4$ in even-even isotopes. Earlier in this approach, we considered multiplets of $ν = 2$ and $ν = 4$ states in isotones with $N = 50$ [3]. It is shown that the approximation of delta interaction is not sufficient to reproduce the energy of first $J = 2$ state. Correct account of this state should allow for description of reversed order of states $J = 4$ with $ν = 2$ and $ν = 4$ observed in experiment.Refs:
1. A.I. Morales et al., Phys. Lett. B 781, 706–712 (2018).
2. P. Van Isacker, Int. J. of Mod. Phys. E 20, 191-198 (2011).
3. M.E. Stepanov et al., Bull. of the RAS: Physics, 82, 697–701 (2018).Speaker: Дарья Жуляева -
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Description of the spectra of the lowest states for a chain of Zr isotopes based on the geometric collective model
The work is devoted to the description of the spectra of the lowest states and transition probabilities for the chain of zirconium isotopes $^{92-102}$Zr in the framework of the geometric collective model. As the mass increases, these isotopes undergo a transition from the spherical structure of the ground state to the deformed one; in $^{96}$Zr, the coexistence of spherical and deformed states is observed. The consideration is based on the collective Bohr quadrupole Hamiltonian, taking into account the triaxial degree of freedom. The selection of the potential parameters for each nucleus was carried out in such a way as to minimize the standard deviation between the available experimental data and the calculated values. The obtained potentials are close in shape to the potentials of the mean field models. Fairly good agreement with experimental data is observed. The deviations of the calculated data for isotopes with a spherical shape are analyzed.
Speaker: Evgenii Mardyban (JINR) -
75
Giant neutron halo in Ce isotopes near the neutron drip line
Neutron halo is one of the most intriguing properties of nuclei with sufficient excess of neutrons. Neutron halo was first observed experimentally in $^{11}Li$. The giant neutron halo of more than two neutrons was predicted also theoretically in medium and heavy mass nuclei near the neutron drip line, in particular in Ca, Zr, Ce. The halo and giant halo forms in $^{186-190}Ce$ and $^{192-198}Ce$ isotopes respectively according to the calculations within the relativistic HFB and RMFPC-CMR-BCS theories [1,2].
We investigated the neutron single-particle structure of Ce isotopes by the dispersive optical model (DOM) [3]. The method to construct dispersive optical model potential is given, for example, in [4]. The evolution of the neutron single-particle energies (see Fig.1) was calculated in the assumption that diffuseness parameter $a_{HF}$ of the potential increased from 0.65 for $^{184}Ce$ to 0.8 fm for $^{198}Ce$. The halo in Ce isotopes near the neutron drip line forms when neutrons occupy low-l states $4s_{1/2}$, $3d_{5/2}$ and $3d_{3/2}$. The calculated root mean square radii $R_{rms}$ of these states are in the interval approx. from 10 to 12 fm, whereas the radii $R_{rms}$ of the neighboring states equal to 6 - 7 fm. The total number of neutrons in halo states exceeds 2 for N > 134. The neutron density distributions of the $^{184}Ce$ with traditional magic neutron number N = 126 and $^{198}Ce$ with N = 140 are shown in Fig.2. For the latter isotope, the neutron density demonstrates the long tail, which can be attributed to the giant halo.Speaker: Olga Bespalova (Moscow State University) -
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ON DETERMINATION OF 82Se TWO-NEUTRINO DOUBLE BETA DECAY MECHANISM AND STERILE NEUTRINOS CONTRIBUTION
Semenov S.V.1, Khruschov V.V.1, Fomichev S.V.1
1 National Research Center "Kurchatov Institute", Moscow, Russia, 123182E-mail: Semenov_SV@nrcki.ru
It is presented the calculation of the amplitude of 22 decay of 82Se on the basis of High-States Dominance (HSD) and Single-State Dominance (SSD) mechanisms [1]. The ground state of the intermediate nucleus 82Br for 22 decay of 82Se has quantum numbers 5-, so contribution of this state in the transition amplitude is very suppressed hence it is needed to take into account exited 1+ states of 82Br [2]. In 82Se decay the excited state of the bromine-82 (82Br*, 11+) with Ex = 75 keV offers a large strength of the Gamow-Teller transition B(GT)=0.338, while high-lying exited 1+ states of the bromine-82 with Ex < 2 MeV exhibit transition strength of order of magnitude lesser. As a consequence one can assume that the SSD hypothesis holds. The alternative is when a transition occurs through a large number of intermediate high excited states then the HSD mechanism takes place and choosing of the mechanism has influence on differential intensities of the decay. The SSD mechanism is supported by measurement data for the electron energy distribution gained at the NEMO-3 [3]. Measurements obtained in the CUPID-0 experiment also point to the SSD superiority for the total electron energy distribution as compared with HSD [4]. Experimental investigation of an electron energy distribution, which is sensitive to a nuclear mechanism, can be used for differentiation of these theoretical approaches [3]. It is found the dependences for the differential intensity of the decay on an electron energy corresponded to HSD and SSD mechanisms. Possible presence of sterile neutrinos also affects a phase factor value [5, 6] that should be taken into account for computation of a no removal background and sensitivity evaluation for experiments in the search for 82Se neutrinoless double beta decay.
- O. Civitarese and J. Suhonen, Phys. Rev. C58, 1535, (1998).
- S.V. Semenov, AIP Conference Proceedings, 942, 67 (2007);
- R. Arnold et al., Eur. Phys. J. C78, 821 (2018).
- O. Azzolini et al., Phys. Rev. Lett. 123, 262501 (2019).
- V.V. Khruschov and S.V. Fomichev, Int. J. Mod. Phys. A34, 1950175 (2019).
- P.D. Bolton et al., arXiv: 2011.13387.
Speaker: Dr Sergei Semenov (Kurchatov Institute) -
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PAIRING ENERGIES OF ODD ACTINIDE NUCLEI IN FIXED QUANTUM STATES
The pairing energies (PE) of nonmagic atomic nuclei with $A \geq 50$ can be derived from the odd nuclei masses $M$ provided it is possible to present $M$ as a sum of two terms [1]:
1) a smooth function of nucleon numbers having the same form of Tailor series expansion for even-even and odd nuclei;
2) PE: $P_{n}\left(N^{\prime}, Z\right)$ and $P_{p}\left(N, Z^{\prime}\right)$, where $N\left(N^{\prime}\right)$ and $Z\left(Z^{\prime}\right)$ denote even (odd) numbers of neutrons and protons and indices $n(p)$ refer to neutron (proton) $\mathrm{PE}$.Traditionally the masses of two adjacent odd nuclei is used for calculations of $\mathrm{PE}$ and this procedure smoothes out the influence of the state of odd nucleon on $\mathrm{PE}$. To overcome this problem, we have proposed [2] the expression for PE, which includes only one odd nucleon mass. This expression is based on the assumptions 1), 2) and Taylor series expansion of mass surface up to the third order in the number of nucleons. For example,
$P_{n}\left(N^{\prime}, Z\right)=M\left(N^{\prime}, Z\right)-\frac{9}{16}\left[M\left(N^{\prime}+1, Z\right)+M\left(N^{\prime}-1, Z\right)\right]+$
$\hspace{2.1cm} +\frac{1}{16}\left[M\left(N^{\prime}+3, Z\right)+M\left(N^{\prime}-3, Z\right)\right]$
The results of calculations of pairing energies of deformed $\mathrm{U}(\mathrm{Z}=92)$ and Pu$(\mathrm{Z}=94)$ actinide nuclei with Nilsson quantum numbers $K^{\pi}\left[N n_{z} \lambda\right]$ of odd neutron quasiparticles are given in the
Table. The masses of nuclei are taken from Atomic Mass Evaluation - AME2020 [3]. The results obtained confirm our conclusion about the dependence of $\mathrm{PE}$ on the state of an odd nucleon.
$ \begin{array}{|c|c|c|c|c|c|c|c|} \hline N^{\prime} & Z & P_{n}, \mathrm{keV} & K^{\pi}\left[N n_{z} \lambda\right] \text{neutrons} & N^{\prime} & Z & P_{n}, \mathrm{keV} & K^{\pi}\left[N n_{z} \lambda\right] \text{neutrons} \\ \hline 141 & 92 & 573 & 5 / 2^{+}[633] & 143 & 94 & 564 & 7 / 2^{-}[743] \\ 143 & 92 & 626 & 7 / 2^{-}[743] & 145 & 94 & 520 & 1 / 2^{+}[631] \\ 145 & 92 & 578 & 1 / 2^{+}[631] & 147 & 94 & 551 & 5 / 2^{+}[622] \\ 147 & 92 & 574 & 5 / 2^{+}[622] & 149 & 94 & 454 & 7 / 2^{+}[624] \\ \hline \end{array} $References:
1. D.G. Madland, J.R. Nix, Nucl. Phys. A 476, 1 (1988).
2. A.K. Vlasnikov, A.I. Zippa, V.M. Mikhajlov, Bull. Russ. Acad. Sci.: Phys. 80, 905 (2016); 81, 1185 (2017); 84, 919 (2020); 84, 1191 (2020); 84, 1309 (2020).
3. https://www-nds.iaea.org/amdc/Speaker: A. K. Vlasnikov (Saint Petersburg State University)
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Section 2. Experimental and theoretical studies of nuclear reactionsConvener: Nikolai Maltcev (St. Petersburg State University (RU))
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SPONTANEOUS AND INDUCED TERNARY AND QUATERNARY FISSION AS A VIRTUAL PROCESSES
In experimental papers [1, 2] the yields, angular and energy distributions of the pairs of light third and fourth particles, such as $\alpha$-particles pair $(\alpha_1,\alpha_2)$, were obtained for the spontaneous quaternary fission of the nuclei $^{252}$Cf, $^{248}$Cm and for the induced by thermal neutrons quaternary fission of compound nuclei $^{234}$U, $^{236}$U. Using the theoretical concepts [3-5] of ternary and quaternary fission as virtual processes [6], we consider spontaneous quaternary fission from the ground states of even-even actinides [1,2] with the sequential emission of two $\alpha$-particles from nuclei A and (A-4) with the formation of the intermediate nuclei $(A-4)$ and $(A-8)$ in the virtual states, and the subsequent binary fission of the residual fissile nucleus $(A-8)$ into light and heavy fission fragments. Induced quaternary fission occur from the excited states of compound nucleus $A$, which is formed when the neutron is captured by the target nucleus, and after that the process goes in the same way as in analogous spontaneous fission. These $\alpha$-particles, in contrast to the $\alpha$-particles that fly out in the sub-barrier $\alpha$-decay from ground states of the studied nuclei $A$ and $(A-4)$, when the energies $Q_{\alpha_1}^A$ and $Q_{\alpha_2}^{(A-4)}$ of this decays are close to $4-6$ MeV, are long-ranged, since their asymptotic kinetic energies $T_{\alpha_1} \approx 16 $ MeV and $T_{\alpha_2} \approx 13 $ MeV, are markedly larger than energy values $Q_{\alpha_1}^A$ and $Q_{\alpha_2}^{(A-4)}$.
The quaternary fission yield $N_{\alpha \alpha f}^A$ normalized to the yield of the binary fission of the nucleus $A$ for spontaneous fission using the formula [4] for the virtual quaternary fission width of nucleus $A$ can be presented as
$ N_{\alpha \alpha f}^A=\frac{1}{(2\pi)^2}\int\int\frac{(\Gamma_{\alpha_1}^A)^{(0)}(T_{\alpha_1})(\Gamma_{\alpha_2}^{(A-4)})^{(0)}(T_{\alpha_2})(\Gamma_{f}^{(A-8)})^{(0)}} {(Q_{\alpha_1}^A-T_{\alpha_1})^2(Q_{\alpha_2}^{(A-4)}-T_{\alpha_2})^2(\Gamma_{f}^A)^{(0)}}dT_{\alpha_1}dT_{\alpha_2}, (1) $
where index (0) denotes to the configuration of fissile nuclei, corresponding to the appearance of two deformed fission prefragments, connected by the neck; $(\Gamma_{\alpha_1}^{A})^{(0)}$ and $(\Gamma_{\alpha_2}^{(A-4)})^{(0)}$ are the width of the $\alpha$-emission from the fissile nucleus neck. In (1) the ratio of the binary fission widths $ (\Gamma_{f}^{A})^{(0)}/(\Gamma_{f}^{(A-8)})^{(0)}\approx 1$. In the case of the induced quaternary fission the energy $Q_{\alpha}^A$ should be replaced by $Q_{\alpha}^A+B_n$, where $B_n$ is neutron binding energy in compound nucleus A. Using Gamov formulae for $(\Gamma_{\alpha_1}^{A})^{(0)}$ and $(\Gamma_{\alpha_2}^{(A-4)})^{(0)}$ , taking into account the fact that the probabilities of formation of the $\alpha_1$ and $\alpha_2$ particles are close to each other and the neck radius $r_{neck}^{A}$ before the emission of $\alpha_1$-particle does not differ from the neck radius $r_{neck}^{(A-4)}$ before the emission of the second $\alpha_2$-particle, the specified estimation of the yield $N_{\alpha \alpha f}$ for spontaneousand induced quaternary can be derived.-
P. Jesinger et al., Eur. Phys. J. A. 2005. V. 24. P. 379.
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M. Mutterer et al., in Proceedings of "Dynamic. Aspects of Nuclear Fission", Slovakia, 2002, p. 191.
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S.G. Kadmensky, L.V. Titova / Physics of Atomic Nuclei. 2013. V. 76. P.16.
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S.G. Kadmensky, O.A. Bulychev / Bull. of RAS: Physics. 2016. V. 80. P. 921.
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S.G. Kadmensky, L.V. Titova, D.E. Lyubashevsky, Phys. Atom. Nucl. 83, 298 (2020).
Speaker: Larisa Titova (Voronezh State University) -
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Advances in modeling of fast neutron induced fission on 232Th
Nuclear data obtained in the neutron induced fission of 232Thorium are of a great importance for advanced fast reactors based on Th fuel cycle. Fission cross sections, mass and charge distributions, prompt emission in fission including neutron multiplicities, yields of some isotopes of interest, and associated uncertainties were obtained. This paper presents the theoretical predictions and the first results on 232Th(n,f) by applying Talys and an author’s computer code for modelling of nuclear reaction mechanisms. Uncertainties induced by nuclear data were quantified using preliminary, energy-dependent relative covariance matrices evaluated with ENDF nuclear data and processed for the studied fission process. Theoretical evaluations obtained are compared with existing experimental data. The present researches on 232Th(n,f) reaction are realized in the frame of nuclear data program running at JINR basic facilities IREN and MT-25 Microtron.
Speaker: Dr Cristiana Oprea (JINR) -
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238U IN THE NEUTRON FIELD AND THE BREMSSTRAHLUNG RADIATION FIELD ON THE BEAMS OF PROTONS AND ELECTRONS OF THE ACCELERATORS AT JINR: CALCULATIONS AND EXPERIMENTS
In the framework of the “Energy and Transmutation of RAW” collaboration [1], the experiments were carried out at the accelerators: Nuclotron, Phasotron and LINAC of JINR and have studied deeply of nuclear inelastic processes using gamma spectroscopy techniques and HPGe detector.
The neutron fields on the proton beam were created using the lead and uranium targets. The field of the secondary bremsstrahlung radiation during the irradiation of the samples on the electron beams was obtained with the use of the lead (or bismuth) converter. The gamma spectra were measured and studied with the HPGe detectors on the spectrometric complex at YASNAPP-LNP and LHEP JINR.
As the result of the study, the yields of the products of the secondary reactions: (n, f), (γ, f) – fission reactions in the 238U samples; (γ, xn) – photonuclear reactions in the 238U, 209Bi samples and also (n, γ) for all the samples.
For the theoretical interpretation of the studied reaction, the simulation programs were used: FLUKA, GEANT4 and MCNP. As the result of simulating, the calculations were made: the distribution of neutrons emitted from the lead targets by energies and coordinates on the proton beam (figure 1); the distribution of the secondary bremsstrahlung radiation (and the secondary neutrons) on the electron beam produced using the Pb or 209Bi converters; the quantitative results of the (n, f) fission reaction products on the proton beams in the 238U samples; the quantitative results of the photonuclear reaction products (n, γ)on the electron beams in the 238U and 209Bi samples.
The calculation estimates of the yields of the capture and fission products in the reactions on the actinide nuclei were made at the energy of the incident charged particles with E > 1 GeV.Fig. 1. The distribution of the neutron emitted from the lead target on the proton beam with E = 660 MeV.
[1] S.I. Tyutyunnikov, V.I. Stegailov et al., “NUCLEUS-2020”. St-Petersburg, 117-118 (2020).Speakers: Mr Toan Tran (Joint Institute for Nuclear Research), Dr Vladimir Stegailov (Joint Institute for Nuclear Research) -
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STUDIES OF ISOMERIC STATES OF NUCLEI ON THE PROTON BEAM OF THE PHASOTRON AND ELECTRON BEAM OF THE LINAC-200 ACCELERATORS AT JINR USING THE 209Bi, 238U, 165Ho TARGETS
The experiments in the framework of the project “Energy and Transmutation” were carried out with the use of the Phasotron and LINAC-200 accelerators at JINR. The samples were placed in the neutron fields produced by the interaction of the proton beam with the lead target or in the bremsstrahlung radiation fields, which were produced in the lead converters irradiated with the electron beams. Gamma spectra of the activated samples were measured using HPGe detectors. The measurement times were from a few minutes to several hours. The yields of the nuclei and their half-life times were studied. Gamma spectra were measured using HPGe detectors on the spectrometric complex at YASNAPP-LNP and LHEP JINR.
- The bismuth and lead residual nuclei in the 209Bi target as the results of (γ, xn) reactions were identified to A =199.
- In the (γ, f) fission and (n, γ) capture reactions, when using the 238U target, more than 30 nuclei of fragments were identified and the fission curve was obtained (see the report of the conference).
- In the irradiation of 165Ho in the field of the bremsstrahlung radiation with an energy of 100 MeV, the decay of the nuclei and their isomeric states were observed to A = 156.
In the result of the experiments on the bremsstrahlung radiation, we observed all the isomeric states in the nuclei of the holmium with A = 155 ÷ 165 [1, 2, 3].
The decay of some nuclei of the holmium and their isomers are shown in Figure 1.Fig. 1. The decay of the Holmium nuclei.
1. V.G. Kalinnikov et al., // “NUCLEUS-2009”. Cheboksary, 148 (2009).
2. V.G. Kalinnikov et al., // “NUCLEUS-2006”. Sarov, 339 (2006).
3. V.I. Stegailov et al., // LV National conference on nuclear physics. St-Petersburg, 72 (2005).Speaker: Dr Vladimir Stegailov (Joint Institute for Nuclear Research) -
3:30 PM
Coffee break
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HIDDEN VARIABLES IN ANGULAR CORRELATIONS OF THE PARTICLES EMITTED IN FISSION
The hidden-variables (HV) theory was once put forward by opponents of the probabilistic interpretation of the wave function (EPR paradox). It was assumed that the state of the system could be predicted with a less uncertainty than this is admitted by the Heisenberg uncertainty principle, if one knew additional, that is HV. This theory is rejected by the community. However, examples can be given of how HV suddenly appear, for example, in modern simulations of the angular distributions of gamma quanta or neutrons emitted from fission fragments. This happens if one considers the spin of each fragment to have a definite direction in the plane perpendicular to the fission axis, and then averages over the directions of the spin in the azimuthal plane. In this way, the well-known phenomenon of the alignment of the spins of fragments in a plane perpendicular to the fission axis might be erroneously treated. Then the supposed direction of the fragment’s spin appears as a HV. Contrary, in a consecutive quantum-mechanical approach, the state of the fragment is characterized by two quantum numbers: the spin and its projection onto the quantization axis z, which is along the fission axis. Then the alignment of the fragments merely means that the projection of their spins onto this axis is close to zero. And in the general case of incomplete alignment, it is necessary to use the density matrix.
A comparative analysis of experiments [1,2] on studying the (n, f), on one hand, and (n, n), on the other hand, angular correlations in fission is carried out, based on the model proposed by muonic conversion in fragments of prompt fission of 238U with negative muons. Their fundamental difference is shown in the sense of the information that can be inferred from them. To show this explicitly, and for the purpose of testing the experimental method, I propose an experimental check of the empirical relation between the alignment and polarization parameters, respectively:
AnJ = 2 Anf .
Among the other examples of use of HV, I point out the use of the immeasurable parameter ξ in the method of specific differences for the elimination of the Bohr—Weisskopf effect in the study of the hyperfine splitting in heavy ions of 209Bi [3].- A. Chietera, L. Stuttge, F. Gönnenwein et al. EPJ A 54, 98 (2018).
- I.S. Guseva, in Proceedings of ISINN-23, Dubna, May 25-29, 2015, JINR, E3-2016-12 (Dubna, 2016), p. 80.
- L. V. Skripnikov, S. Schmidt, J. Ullmann et al. Phys. Rev. Lett. 120, 093001 (2018).
Speaker: Feodor Karpeshin -
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Joint report: DISTORTIONS OF THE REGISTRATION OF DELAYED NEUTRONS FROM 238U FOTOFISSON BY A SCINTILLATION SPECTROMETER IN Pb PROTECTION BETWEEN LEA PULSES AND POSSIBILITY OF ISOLATING A COMPONENT WITH T1 / 2 = 1 ms.
In previous works [1–3], we measured spectra of delayed neutrons (DNs) from photofission of 238U and looked for short-lived components in these DNs (with half-life T1/2 down to 1 ms) in time intervals between pulses of the linear electron accelerator at the energy of incident on metal U-target electrons Ee = 10 MeV. Fast neutrons were registered by scintillation stilbene (thickness 50 mm, diameter 50 mm) spectrometer with discrimination of background g-quanta using differences in shapes of scintillation pulses. This spectrometer has Pb-shielding (thickness 5 cm). In order to avoid negative influence on the used scintillation detector from background of g-quanta and neutrons, produced by beam pulses, the controlled divider of power supply for the photomultiplier tube of the scintillation detector [4] was used (especially important for short-lived groups of DNs). For more details see [1–4] and references therein.
In the present work we considered distortions in registered spectra of DNs using Monte Carlo simulation for transport of DNs by codes LOENT and SHIELD [5–7] taking into account, first of all, interactions of DNs with atomic nuclei of Pb-shielding for stilbene spectrometer.1. L.Z.Dzhilavyan, et al. Phys. Part. Nucl. 50, 626 (2019). 2. L.Z.Dzhilavyan, et al. Bull. Russ. Acad. Sci. Phys. 84, 356 (2020). 3. L.Z.Dzhilavyan, et al. Phys. Atom. Nucl. 84, (2021). 4. L.Z.Dzhilavyan, et al. Bull. Russ. Acad. Sci. Phys. 83, 474 (2019). 5. L.N.Latysheva, N.M.Sobolevsky. LOENT – the code for Monte Carlo simulation of neutron transport in complex geometries. Preprint INR RAS No 1200/2008. 6. https://www.inr.ru/shield/ 7. A.V.Dementyev, N.M.Sobolevsky. SHIELD – Universal Monte Carlo Hadron Transport Code. Scope and Applications. // Radiation Measurements. 1999. Vol. 30. P. 533. https://doi.org/10.1016/S1350-4487(99)00231-0Fission of actinide nuclei produces fast neutrons, mainly “prompt” neutrons (PNs), but also (2%) “delayed” neutrons (DNs with different half-lives T1/2). Usually, for the sake of convenience, DNs are divided into 6–8 groups according to their T1/2-values at approximately 0.2 s < T1/2 < 56 s (see, e.g., [1]). But there are some indications that it is necessary to search for short-lived DNs with T1/2 down to 1 ms (see, e.g., [2]).
In previous works [3–5], we tried to find such short-lived DN-components in time intervals between pulses of the linear electron accelerator LUE-8-5 of the INR RAS [6] at the incident electron energy Ee = 10 MeV, the duration of each beam pulse 3 (10^-6)s, and their repetition rates (50–300)s(^-1). As we showed in [4], under such conditions, after about 7 min of irradiation with beam with stable parameters, flux of all DNs with 0.2 s < T1/2 < 56 s will be almost constant at an aggregated saturation level (except for some statistical fluctuations). Under these conditions, the sought short-lived component of DNs will give an addition to this level which will decrease exponentially with increasing of t – time after beam pulse (from t = t0 – start of each measuring interval).
In the present work, we considered possibility for separating a short-lived component with T1/2 = 1 ms from total quantity of DNs at photofission of 238U in dependence on as characteristics of DNs (namely, ai – the relative part of the i-th group of delayed neutrons), as characteristics of used registration process (values of t0 and levels of accumulated “statistics”).1. V.M.Piksaikin, et al., Voprosy Atomnoy Nauki i Tekhniki. Seriya: Yaderno-reaktornye konstanty. Vypusk 1. P. 184 (2019). 2. S.B.Borzakov, et al., Study of Delayed Neutron Decay Curves at Fission of 235U and 239Pu by Thermal Neutrons. // Voprosy Atomnoy Nauki i Tekhniki. Seriya: Yaderno- reaktornye konstanty. Vypusk 2, (1999). 3. L.Z.Dzhilavyan, et al., Phys. Part. Nucl. 50, 626 (2019). 4. L.Z.Dzhilavyan, et al., Bull. Russ. Acad. Sci. Phys. 84, 356 (2020). 5. L.Z.Dzhilavyan, et al., Phys. Atom. Nucl. 84, (2021). 6. G.Nedorezov, et al., Bull. Russ. Acad. Sci. Phys. 83, 1161 (2019).Speaker: Dzhilavyan L.Z., 1 (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia) -
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237Np, 239Pu ACTINIDES IN THE NEUTRON FIELD OF THE “QUINTA” URANIUM TARGET
The study of the production of actinides in the neutron field of the “Quinta” uranium target was carried out within the framework of the “Energy – Transmutation” project at the accelerators of JINR: Nuclotron and Phasotron.
The purpose of this work is to compare the yields of capture and fission reactions at various energies of the charged particles in a range from 1 to 20 GeV, determine their relation [3] for the residual nuclei in the 237Np sample and compare with the ratio in the 239Pu sample.Fig. 1. The fission and capture yields for 237Np [2].
Fig. 2. Comparison of gamma spectra of 237Np samples, irradiated with the proton beam (A) and the secondary neutrons (B) at the distance of 200 mm from the proton beam in the “Quinta” uranium target.
The studies were carried out using HPGe detectors on the spectrometric complex at YASNAPP-LNP and LHEP JINR. The reliability of the studies is confirmed by the presence of the gamma transition with energy 984.5 keV and 1028.5 keV arising in the presence of the neutron capture with the 237Np nucleus in the “B” gamma spectra (Fig 2).
To interpret the results obtained in Figure 1, the report discusses the possibility of the cumulative data from the experiments on multifragmentation [1].
1. S.P. Avdeyev, W. Karcz, V.I. Stegailov et al., // Bull. Russ. Acad. Sci. Phys, 84, 979-980 (2020).
2. S. Kilim, S.I. Tyutyunnikov, V.I. Stegailov et al., // NUKLEONIKA 63(1), 17-22 (2018).
3. S. Kilim, S.I. Tyutyunnikov, V.I. Stegailov et al., // XXIII Inter. Baldin Seminar, Dubna, 80-81 (2016).Speakers: F.A. Rasulova (Joint Institute for Nuclear Research, Dubna), Dr V.I. Stegailov (Joint Institute for Nuclear Research, Dubna) -
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THE FIRST EXPERIMENTS AT E = 180 MEV ON THE ELECTRON BEAM OF THE LINAC-200 ACCELERATOR TO DETERMINE ISOMERS OF BISMUTH AND LEAD
In the framework of the “Energy + Transmutation” [1] project, the experiments have been carried out at the LINAC-200 accelerator of JINR. The 209Bi samples were irradiated in the field of bremsstrahlung radiation by the 180 MeV electrons. The bismuth was used as a converter to obtain the bremsstrahlung radiation, Figure 1.
The gamma spectra of the 209Bi activated samples were studied using HPGe detectors in a range from 40 to 3000 keV on the spectrometric complex at YASNAPP-LNP and LHEP JINR. The identification of the nuclei and their yields obtained in the 209Bi sample as a result of the irradiation and were carried out under the periods of the half-life time and the ratio of the intensities of the gamma rays in the spectra as well as compared the results with literary data on the study of 209Bi (γ, xn) reactions [2].
The yields of the bismuth nuclei obtained in (γ, xn) reactions at the electron energies E = 60 and 180 MeV are shown in Figure 1.
The yield of the isotopes with A = 202 for E = 180 MeV is up to more than ten times compared with the yield at E = 60 MeV, which makes it possible to effectively study the isomers and structure of the bismuth nuclei and lead with masses of A from 199 to 203.Fig. 1. The relative yields of the (γ, xn) reactions in 209Bi.
1. S.I. Tyutyunnikov, V.I Stegailov et al., // “NUCLEUS-2020”. St-Petersburg, 117-118 (2020).
2. S.S. Belyshev et al., // Eur. Phys. J. A 51, 67 (2015).Speakers: F.A. Rasulova (Joint Institute for Nuclear Research, Dubna), Dr Vlardimir Stegailov (Joint Institute for Nuclear Research)
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Section 3. Modern nuclear physics methods and technologiesConvener: Vladimir Zherebchevsky (St. Petersburg State University)
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86
New technologies for the vertex detectors at the NICA collider experiments
In modern high energy physics and elementary particle physics experimental research, one of the important problems is connected with the study of the yields of the hadrons containing heavy quarks. These hadrons practically do not interact (low interaction cross sections) with the nuclear medium and, therefore can provide undistorted information about the states of nuclear matter arising in the relativistic nuclei collision processes. Thus, an effective registration of strange and charmed particles by the experimental setup in the nucleus-nucleus collisions at the NICA collider plays a key role in the analysis of possible nuclear matter evolution and its phase transitions mechanisms. In addition, at relatively low energies of the colliding nuclei at the NICA collider ($\sqrt {s_{NN}}$ = 4 - 11 GeV) [1], it becomes possible to study inside the nuclei the different clusters of dense nuclear matter [2].
The number of secondary particles produced in central collisions of relativistic ions can reach several thousand in the energy range of the NICA collider. For precise registration of these events we need the vertex detector systems, which allow reconstructing the tracks of primary charged particles and products of their decays. These detector systems should provide the ability to reconstruct the decay vertices of short-lived multi-strange and charmed hadrons with high spatial resolution at minimum material budget. Therefore, the leading high energy and elementary particle physics experiments: ALICE, ATLAS, CMS at the Large Hadron Collider (LHC), STAR at the Relativistic Heavy Ion Collider (RHIC) are using now the silicon pixel sensors as the main element of the whole tracking system [3].
In present overview the technologies for the vertex detectors at the NICA collider experiments together with new ultra-light radiation-transparent carbon fiber support structures as basic elements for these detectors and CMOS monolithic active pixel sensors are discussed. To investigate the efficiency and main characteristics of the proposed carbon fiber support structures and pixel sensors, the comprehensive studies with gamma, beta sources, with cosmic rays and also with different cooling systems were carried out.Acknowledgments: the reported study was supported by RFBR, research project No. 18-02-40075.
- V.Kekelidze, V.Matveev, I.Meshkov, A.Sorin, G.Trubnikov, Physics of Particles and Nuclei, Vol. 48, No. 5, pp. 727–741 (2017).
- V.I. Zherebchevsky, V.P. Kondratiev, V.V. Vechernin, S.N. Igolkin, Nuclear Inst. and Methods in Physics Research, A 985,164668 (2021).
- ALICE collaboration, Technical design report for the upgrade of the ALICE Inner Tracking System, Journal of Physics G: Nuclear and Particle Physics, vol. 41, iss. 8, P087002 (2014).
Speaker: Dr Vladimir Zherebchevsky (St Petersburg State University (RU)) -
87
Simulation of ToF performance of ECal MPD/NICA
A cylindrical electromagnetic calorimeter with a length of 6 m and an inner (outer) diameter of 3.45 (4.6) m, composed of 38400 trapezoidal towers with a base of 4x4 cm2 and a length of 40 cm, is created to operate as part of the MPD detector of the NICA project. “Shashlyk” technology was used for tower development with 210 alternating layers of lead and a scintillator 0.3 and 1.5 mm thick, pierced with 16 wavelength-shifting fibers to collect light on a silicon photomultiplier. Calorimeters of this type can provide subnanosecond time resolution that can be used for neutron identification, background suppression, and separation of hadron and electromagnetic showers. Because of the complexity of the light collection process, the time response simulation of a calorimeter presents significant difficulties. In full, this task comes down to obtaining the distribution of energy release in scintillators, converting it into photons of blue light, collecting these photons on wavelength-shifting fibers, converting and capturing green photons in fibers, transporting them to a multipixel APD, shaping its output signal and registering with digital electronics. The current status of the simulation program is discussed, as well as the results of time measurements on the manufactured calorimeter modules using electron beam. This work was supported by the RFBR grant no. 18-02-40054.
Speaker: Dr V.V. Kulikov (NRC ”Kurchatov Institute” - ITEP, Moscow 117218, Russia) -
88
Luminosity determination with ALICE at the LHC
Cross section measurements in hadronic collisions are crucial to the physics program of ALICE. These measurements require a precise knowledge of the luminosity delivered by the LHC. Luminosity determination in ALICE is based on the measurement of visible cross sections in dedicated calibration sessions, the van der Meer (vdM) scans. By combining information from the ALICE detectors and the LHC instrumentation, a per cent level of precision on luminosity can be achieved. This contribution presents a review of the ALICE luminosity determination methodology and results during the LHC Run 2. In particular, new results will be presented for pp collisions at $\sqrt{s}$~=~13~TeV and for Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$~=~5.02~TeV. The latter include a measurement of the inelastic hadronic interaction cross section.
Speaker: Artur Furs (Russian Academy of Sciences (RU)) -
3:05 PM
Coffee break
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Study of performance of Fast Beam-Beam Collision monitor system with MC simulations and machine learning methods
New experiments are being planned at the NICA collider beams aimed to explore the properties of high-density baryonic matter formed in heavy-ion collisions with energies up to $\sqrt{s_{NN}}=11$ GeV. With the aim of selecting the collision events of interest, it was proposed in [1] to develop a fast beam-beam collision monitor (FBBC) system, which would be capable to determine the time and space of each ion-ion collision.
In this report, we consider a system of 6 segmented ring-shaped detectors based on the microchannel plates (MCP) placed in the vacuum of the beam-pipe at some distance along the beam-line on both sides from the center of the experimental facility. Intrinsic high timing characteristics of MCPs (signal duration below 1 ns) allow to consider the required functionality of the FBBC for monitoring the luminosity of collisions and to provide the event selection, precise event timing information, determination of the event interaction point, and suppression of the beam-gas interaction events.
MC simulations of the beam-beam collisions monitoring system were performed within the DQGSM[2] event generator. Taking into account the information about the multiplicity of registered charged particles and their time-of-flight, the position of the interaction point and multiplicity/centrality in the event were estimated. To perform such estimations, different machine learning methods were used. It is shown that the monitoring system and machine learning algorithms can provide an interaction point position within the acceptance of the experiment with the precision of about $\pm 1.6$ cm at least; also the ability of the system to distinguish peripheral and central collisions is discussed.This work is supported by the RFBR grant №18-02-40097/19
- A.A. Baldin, G.A. Feofilov, P. Har’yuzov, F.F. Valiev, NIMA958(1), 162154 (2020).
- K.K. Gudima, S.G. Mashnik, A.G. Sierk, Report LA-UR-01-6804, Los Alamos (2001).
Speaker: Vladislav Sandul (St Petersburg State University (RU)) -
90
Implementation of high-performance computing technologies in the BmnRoot framework
The purpose of the BM@N experiment at NICA accelerator complex in Joint institute for Nuclear Research (Dubna, Russia) is study of heavy-ion collisions with fixed targets. Successful study requires efficient algorithms of event reconstruction and particle identification using data from the detector subsystems of the facility as well as its efficient and high-performance software implementation in the BmnRoot package. Development and study of such algorithms, their software implementation and optimization of the existing software components of the BmnRoot are subjects of the report. Implementation of simulation and reconstruction algorithms for hybrid computing systems are also discussed.
The study was supported by RFBR grant № 18-02-40104 mega.Speaker: Sergei Nemnyugin (Saint Petersburg State University) -
91
Neural network application to event-wise estimates of the impact parameter
Evaluation of the impact parameter in a single event is crucial for correct and efficient data processing in collision-based nuclear and particle physics experiments. Real-time estimates of the impact parameter allows experimentalists to preselect the most informative events at the data acquisition stage, before any processing. Here we consider a number of model setups to check whether a neural network can evaluate the impact parameter from the spacial and time-of-flight data collected in real time by a set of inexpensive microchannel plate ring detectors.
We evaluate several detector geometries, including the geometries considered for SPD detector [1] at NICA, and several neural network architectures.We have shown that even low spacial resolution detectors in realistic geometry would make it possible to separate low $-$ less than 6 fm $-$ impact parameter events from other collisions with 84% probability.
The analysis of the full $4\pi$ geometry would rise the probability of the low impact parameter collision identification to 97%. Appropriate usage of the time of flight information is crucial to obtain these results. Without time information the quality of identification of low impact parameter events does not exceed 64%, with especially high contamination from high $-$ greater than 12 fm $-$ impact parameters.The presented computational experiments prove application of neural network techniques for direct impact parameter evaluation useful for future experimental setups.
This work is partially supported by Russian Foundation for Basic Research grants 18-02-40104 mega and 18-02-40097 mega.
- V.M. Abazov et al., arXiv:2102.00442v2 (2021).
Speaker: Kirill Galaktionov (St Petersburg State University (RU)) -
92
Efficiency study of the ECal detector of the HADES experiment
The High Acceptance DiElectron Spectrometer (HADES) is a fixed target experiment which explores the properties of hadronic matter in collisions of pions, protons and nuclei at beam energies 1-2 AGeV. Currently the HADES experiment operates at the SIS18 accelerator in GSI, Darmstadt. When the SIS100 accelerator is built, HADES will be the first experiment in FAIR Phase-0 project.
In order to extend capabilities of HADES in measurements of hyperons and neutral mesons, the new electromagnetic calorimeter ECal was built. In March 2019 the ECal detector was used for the first time in measurements of Ag+Ag collisions at beam energies 1.58 and 1.23 AGeV. The calibration of ECal was done using electrons and positrons emitted in collisions. Their identification and measurement of momentum was carried out by the RICH, MDC and RPC detectors.
This talk describes the procedure of the ECal efficiency determination with usage of machine learning.Speaker: Arseniy Shabanov (Russian Academy of Sciences (RU)) -
5:30 PM
End of session
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physicsConvener: Igor Altsybeev (St Petersburg State University (RU))
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93
Soft-QCD studies in ALICE: focus on forward particle multiplicities and the underlying event
It is well-established that high-multiplicity pp and p–Pb collisions exhibit a collective-like behaviour and signatures, like the strangeness enhancement and the ridge behaviors, that were commonly attributed to the formation of the Quark-Gluon Plasma. These processes, which are typically described by phenomenological models and soft QCD measurements, provide important constraints on the model parameters. Thus, the study of system size dependence of particle production and characterisation of underlying events is crucial.
We present measurements of charged and neutral particle production in the forward rapidity range (-3.4 < $\eta$ < 5.0 and 2.3 < $\eta$ < 3.9) exploiting the full coverage of the ALICE detector at forward rapidities. The evolution of the width of the pseudorapidity density distribution with centrality is shown and a lower bound on the Bjorken energy density for different collision systems is extracted. We also present results obtained using Underlying Event (UE) techniques, allowing the measurement of the average number density in the Toward, Transverse, and Away regions with respect to the leading trigger particle. For the first time at the LHC, an analysis, based on UE measurements, is applied also to p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV to test the similarities between pp and p-Pb collisions. The charged particle multiplicity in the Transverse UE-dominated region, $N_{\rm TS}$, is used as a multiplicity estimator to study particle production mechanisms in pp, p-Pb and Pb-Pb collisions at the same center-of-mass energy. Finally, the UE studies are used to search for jet-like modification by subtracting the UE contributions measured in the Transverse region from the Toward and the Away regions. The results are compared with predictions from QCD-inspired Monte Carlo event generators with different particle-production mechanisms and initial conditions.
Speaker: Christian Holm Christensen (University of Copenhagen) -
94
Collective dynamics of heavy ion collisions in ATLAS
This talk gives an overview of the latest measurements of collective behavior in a variety of collision systems with the ATLAS detector at the LHC, including pp collisions at 13 TeV, Xe+Xe collisions at 5.44 TeV, and Pb+Pb collisions at 5.02 TeV. These include measurements of vn-[pT] correlations in Xe+Xe and Pb+Pb, which carry important information about the initial-state geometry of the Quark-Gluon Plasma and can potentially shed light on any quadrupole deformation in the Xe nucleus; measurements of flow decorrelations differential in rapidity, which probe the longitudinal structure of the colliding system; and measurements of the sensitivity of collective behavior in pp collisions to the presence of jets, which seek to distinguish the role that semi-hard processes play in the origin of these phenomena in small systems. These measurements furthermore provide stringent tests of the theoretical understanding of the initial state in heavy ion collisions.
Speaker: Adam Trzupek (Institute of Nuclear Physics Polish Academy of Sciences (PL)) -
95
Global polarization of $\Xi$ hyperons in Au+Au collisions in the STAR experiment
The hot dense matter produced in non-central heavy-ion collisions possess a large initial orbital angular momentum. This initial orbital angular momentum leads to global polarization of hadrons produced after hadronization, which could be measured via CP-violating weak decays of hyperons.
The STAR experiment observed non-zero $\Lambda$ global polarization. Large amount of new data provided opportunities to measure multistrange hyperon polarization. It could be important input for hydrodynamic studies of system.
It this talk, we will report results of $\Xi$ hyperon global polarization ($P_{\Xi^{-}+\overline\Xi^{+}}$) measurement for Au+Au collisions at $\sqrt{s_{NN}}$ = 27, 54.4 GeV and 200 GeV.Speaker: Egor Alpatov (NRNU MEPhI) -
96
Hard probes of heavy ion collisions with ATLAS
This talk gives an overview of the latest hard process measurements in heavy ion collision systems with the ATLAS detector at the LHC, utilizing the high statistics 5.02 TeV Pb+Pb data collected in 2018. These include multiple measurements of jet production and structure, which probe the dynamics of the hot, dense Quark-Gluon Plasma formed in relativistic nucleus-nucleus collisions; measurements of electroweak boson production to constrain the modifications of nuclear parton densities and test the Glauber model and binary scaling picture of heavy ion collisions; and measurements of quarkonia and heavy flavor production to probe the QGP medium properties. A particular focus of the measurements is the systematic comparison of fully unfolded data to state of the art theoretical models.
Speaker: Martin Krivos (Charles University (CZ)) -
97
Jet substructure measurements with ALICE
Jet substructure measurements, based on the distribution of constituents within a jet, are able to probe specific regions of QCD radiation phase space for jet showers in vacuum. This powerful capability provides new opportunities to study fragmentation patterns of parton showers in vacuum and the dynamics of jet quenching in heavy-ion collisions.
The ALICE experiment has unique capabilities for jet substructure measurements, due to its high-precision tracking system and focus on jets with low transverse momenta. The excellent tracking of the ALICE detector also allows the study of jet substructure in the heavy-flavour sector by tagging jets with fully reconstructed charm hadrons. Heavy-flavour jets are declustered to trace all branchings of the charm quark and to reveal mass dependence of the shape and structure of the parton shower due to the dead-cone effect.
In this talk, we report several new jet substructure measurements in pp and Pb–Pb collisions by the ALICE Collaboration. These include the first fully corrected inclusive measurements of the groomed jet momentum fraction, $z_{\text{g}}$, and the groomed jet radius, $\theta_{\text{g}} \equiv R_{\text{g}}/R$, as well as the $N$-subjettiness distribution and the fragmentation distribution of reclustered subjets. We also report on the measurement of several groomed substructure observables of heavy-flavour jets in pp collisions, fragmentation functions and the new measurements of the radial distributions of $\text{D}^{0}$ mesons or $\text{Λ}_{\text{c}}^{+}$ baryons in jets. The measurements will be compared to theoretical calculations and provide new constraints on the physics underlying parton fragmentation and jet quenching.
Speaker: Robert Vertesi (Wigner Research Centre for Physics (Wigner RCP) (HU)) -
3:55 PM
Coffee break
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98
Production of K*(892)0 mesons in small collision systems at PHENIX experiment
The investigation of nuclear matter effects in relativistic ion collisions, especially quark-gluon plasma (QGP) ones, is one of the main goals of PHENIX experiment [1]. To study the dynamics of collisions at high energies, strange hadron production is considered as a significant tool. Due to its strange quark content, the $K^{*0}$ meson is a good probe for the investigation of such QGP effects as strangeness enhancement and flavor dependence of partonic energy loss [2]. New results of the PHENIX experiment on hadron production and elliptic flow in small collision systems suggested the possibility of QGP formation in such systems [3]. Thus, the measurement of $K^{*0}$ mesons production in small collision systems allows to investigate aspects of QGP formation depending on the collision system size. We have performed analyses of $K^{*0}$ meson production in wide set of small systems such as p+Al, p+Au, and $^{3}$He+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.
In this talk, we present invariant transverse momentum ($p_{T}$) spectra and nuclear modification factors ($R_{AB}$) of $K^{*0}$ meson as a function of $p_{T}$ measured in p+Al and p/$^{3}$He+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Nuclear modification factors of K0 meson in p+Al and p/d/$^{3}$He+Au collisions are in a good agreement at $p_{T}$ < 2 GeV/c whereas at intermediate-pT range (2 GeV/c < $p_{T}$ < 5 GeV/c) a hint of ordering is observed. $R_{AB}$ values for $K^{*0}$, $\varphi$, and $\pi^{0}$ mesons fall on the same curve in all centrality bins in favor of strangeness enhancement effect absence.
- K. Adcox et al., Nucl. Phys. A 757, 184-283 (2005)
- V.P. Kondratev and G.A. Feofilov, Elementary Particle and Nuclear Physics 42, 6 (2005)
- A. Accardi et al., Phys. Lett. B 586, 244-253 (2004)
Speaker: Vladislav Borisov (Peter the Great St.Petersburg Polytechnic University (SPbPU)) -
99
Measurement of charged hadron production in relativistic ion collision systems
Measurement of charged hadron production in relativistic ion collision systems is one of the main methods to study hadronization of quark gluon plasma (QGP) - a state of matter, which is thought to consist of asymptotically free quarks and gluons [1]. According to QCD calculations, conditions in small collision systems are not sufficient for QGP formation, but flow studies in the PHENIX experiment established the evidence of possible QGP formation in such systems [2]. Therefore, investigation of charged hadron production in small collision systems is important to distinguish cold nuclear matter effects and possible QGP effects.
Theoretical calculations of charged hadron production in small collision systems can be provided by Angantyr model in Pythia8 [3], which is generalized the formalism for pp collisions to an event generator for nuclei collisions and consequently considers only cold nuclear matter effects. Therefore this model can serve as an effective tool for studying non-collective background to observables sensitive to collective behavior.
This talk will present PHENIX results on identified hadron production in small collision systems. Nuclear modification factors and ratios of identified charged hadrons ($\pi^{\pm}$, $K^{\pm}$, $p$ and $\bar{p}$) as a function of $p_T$ and centrality measured in p+Al and $^{3}$He+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV will be presented. Comparison of obtained experimental data with theoretical predictions based on the Angantyr model in Pythia8 will be discussed.
- A. Adare et al., Phys. Rev. C 83, 064903 (2011)
- PHENIX Collaboration, Nat. Phys. 15, 214–220 (2019)
- C. Bierlich et al., High. Energ. Phys. 2018, 134 (2018)
Speaker: Ms Daria Larionova (Peter the Great St.Petersburg Polytechnic University (SPbPU)) -
100
Investigation of light flavor particle production at the MPD experiment
Precise study of heavy ion collisions in the energy range $\sqrt{s_{NN}}$ = 4 - 11 GeV is one of the key features of the NICA complex which is currently under construction at JINR (Dubna). Current experimental results in this area suggest this energy region as the most interesting to study the QCD phase diagram and search for phase transition and possible Critical Point. The MPD experiment at NICA will perform Bi+Bi collisions with $5*10^{25}$ luminosity for the first physics runs and will switch to Au+Au collisions with higher luminosity in later runs allowing us to collect high statistics for comprehend analysis.
We present recent results on light flavor particle production, centrality determination and nuclear modification factor at the energy range $\sqrt{s_{NN}}$ = 7.7 – 11 GeV. Charged pion and kaon production in different centrality regions is calculated for several MC models. Nuclear modification factor $R_{CP}$ and pion to kaon ratios are presented.
We discuss measurements that will be performed on the first experimental data of the MPD experiment.Speaker: Alexey Aparin (JINR) -
101
Energy and mass dependencies for the characteristics of $p_T$ regions observed at LHC energies
The $p_T$ distributions of the $K^0$- and $\phi$ - mesons produced in the $pp$ collisions at $\sqrt{s}=2.76$ $TeV$ have been analyzed by fitting them using the exponential function. It was observed that the distributions contain several $p_T$ regions similar to the cases with the charged particles, $\pi^0$- and $\eta$- mesons produced in the same events. These regions could be characterized using three variables: the length of the region $L^{c}_K $ and free fitting parameters $a^{c}_K $ and $b^{c}_K $. It was observed that the values of the parameters as a function of energy grouped around certain lines and there are jump-like changes. These observations together with the effect of existing the several $p_T$ regions can say on discrete energy dependencies for the $L^{c}_K $ , $a^{c}_K $ and $b^{c}_K $. The lengths of the regions increase with the mass of the particles.This increase gets stronger with energy. The mass dependencies of the parameters $a^{c}_K $ and $b^{c}_K $ show a regime change at a mass $\simeq 500 MeV/c^2$. According to the phenomenology of string theory, these results could be explained by two processes occurring simultaneously: string hadronization and string breaking. In the experiment we can only measure the spectrum of the hadronized particles, since we cannot access the spectrum of the strings themselves. The string breaking effect could be a signal of string formations and the reason behind the observation of several $p_T$ regions and the jump-like changes for the characteristics of the regions.
Speaker: Prof. Suleymanov Mais (Baku State University)
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93
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Section 5. Neutrino physics and astrophysicsConvener: Egor Zemlin (Saint Petersburg State University, Russia)
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102
Nuclear inelastic scattering effect in spectra of neutrinos at weak coupling regime
Effect of inelastic nuclear scattering in magnetized hot and dense matter in neutrino spectra relevant for supernovae, neutron star mergers, proto-neutron stars is considered. At finite temperature neutrino exhibits exo- and endoenergetic scattering on nuclear species due to the neutral-current Gamow-Teller interaction component. The kinetic equation for neutrino transport at decoupling regime is derived from an analysis of energy transfer cross sections [1] due to additional noticeable mechanisms of energy exchange. The energy transfer coefficient is shown to change from positive to negative value at neutrino energy increasing four times the matter temperature. Such a property results in focusing neutrino energy.
[1] V. N. Kondratyev, et al. // Phys. Rev. C 2019. V. 100, 045802Speaker: Vladimir Kondratev -
103
INTERPRETATION OF THE XENON1T EXCESS IN THE DECAYING STERILE NEUTRINO MODEL
The observed excess of electronic recoil events in the XENON1T experiment with energies from 1 to 7 keV [1] is considered in the framework of the phenomenological model with three active and three sterile neutrinos [2]. Assuming sterile neutrinos with appropriate masses in the several keVs domain to be decaying [3], it becomes possible to interpret the observed energy spectrum of electronic recoil events. Using this approach allows one to predict several peaks in the energy range of 1 - 7 keV for electronic recoil events owing to dark photons and photons emitted in this energy range [4, 5]. To study oscillations with decaying sterile neutrinos analytical expressions are obtained for transition and surviving probabilities for different neutrino flavors and the graphs of these probabilities are presented at some test values of model parameters.
- E. Aprile et al. (XENON collab.), and X. Mougeot, Phys. Rev. D102, 072004 (2020).
- V.V. Khruschov and S.V. Fomichev, Int. J. Mod. Phys. A34, 1950175 (2019).
- V.V. Khruschov, arXiv: 2008.03150.
- A.E. Nelson and J. Scholtz, Phys. Rev. D84, 103501 (2011).
- P. Arias et al., JCAP 1206, 013 (2012).
Speaker: Dr V.V. Khruschov ( National Research Center "Kurchatov Institute") -
104
SHAKE AS THE PREDETERMINING MECHANISM OF THE NEUTRINOLESS DOUBLE ELECTRONIC CAPTURE
The process of double neutrinoless e-capture is of great interest as a test of the Majorana nature of neutrino This process is traditionally considered as a resonance one, since not a single particle is emitted as a result of the nuclear transformation [1]. In contrast, we performed calculations of the probability of shake off and shake up, with the ionization or excitation of the electron shell during the nuclear transformation. $^{164}$Er nucleus is one of the main candidates for discovering the neutrinoless mode of the process [2]. As a result, the contribution of the new mechanism turns out to be three times stronger than that of the traditional resonance mechanism [3]. It rapidly increases with the increasing resonance defect, thus becoming the main mechanism of the double neutrinoless electron capture. One can conclude that account of the shake mechanism generally increases the decay rate by an order of magnitude. Therefore, the double neutrinoless e-capture appears not to be a resonance process at all. This considerably increases the chance for successful experimental research of the process.
References:
1. Z. Sujkowski and S. Wycech, Phys. Rev. C 70, 052501 (2004).
2. S. A. Eliseev, Yu. N. Novikov, and K. Blaum, J. Phys. G 39, 124003 (2012).
3. F. F. Karpeshin, M. B. Trzhaskovskaya, L. F. Vitushkin, Yad. Fiz. 83, 344 (2020) [Phys. At. Nucl. 83, 608 (2020)]; arxiv:2008.03906.Speaker: Feodor Karpeshin -
105
RESONANCE STRUCTURE OF NEUTRINO CAPTURE CROSS SECTION BY 100Mo NUCLEI
The work presents calculations of the solar neutrino capture cross-section σ(Eν) by 100Mo nuclei. In calculations experimental data on strength function S(E), received in charge-exchange reactions (3He, t) [1, 2] were used. Within the framework of the self-consistent theory of finite Fermi systems, the charge-exchange strength function S(E) for this nucleus is calculated. The influence of the resonance structure of the strength function S(E) on the calculated cross section for the capture of solar neutrinos was investigated. The influence of the Gamow-Teller [3], analog [4] and pygmy resonances [5] is taken into account, and the contributions of each resonance to the cross section for the capture of solar neutrinos σ(Eν) by the 100Mo nucleus was distinguished. The question of changing the neutrino capture cross section due to taking into account the effect of neutron emission from the daughter nucleus is considered. The contribution of all components of the solar neutrino spectrum is calculated. It was noted that the capture of solar neutrinos by the 100Mo nucleus is a background process in the study of double beta decay of this nucleus.
The work is partial supported by the grant of the Department of Neutrino Processes of the National Research Center “Kurchatov Institute”.Speaker: Алексей Осипенко (Национальный Исследовательский центр “Курчатовский Институт”,Москва, Россия) -
3:30 PM
Coffee break
-
106
SELF-CONSISTENT CALCULATIONS ОF SOLAR CNO NEUTRINO CAPTURE-RATES FOR 115In.
I.N. Borzov 1,2
1 National Research Centre “Kurchatov Institute”, 123182, Moscow, Russia
2Bogolubov Laboratory of Theoretical Physics, Joint Institute of Nuclear Research, 141980,
†E-mail: Borzov_IN@nrcki.ru, cc: ibor48@mail.ruThe first direct detection of the neutrinos from carbon-nitrogen-oxygen (CNO) fusion cycle in the Sun has been announced recently by the BOREXINO Collaboration [1]. An estimate of possible “CNO-like” events induced by geo-antineutrino from 40K decay in the Hydride model of the Earth has been done in [2]. This has revived attention to the additional experimental prospects given by improved 115In detector system (LENS Project [3]).
In the report, the CNO neutrino capture rates for 115In are calculated within a revised self-consistent approach to the charge-exchange excitations of odd-A nuclei [4]. It includes new version of the Fayans functional DF3-a fitted to the spin-orbit splitting data for 105 nuclei [5]. The β-decay strength function is calculated within continuum Quasiparticle Random Phase (pnQRPA) approximation including the Gamow-Teller and first-forbidden transitions [6].Supported by the grant of Russian Scientific Foundation (RSF 21-12-00061).
- M. Agostini M., K. Altenmuller, S. Appel et al. for BOREXINO Collaboration
// arXiv:2006.15115. 2020. - L.B. Bezrukov et.al., Izvestia RAN 85, (4), 566 (2021).
- R.S. Raghavan, The LENS Experiment: Spectroscopy of Low Energy Solar Neutrinos,
Neutrino 2010, Athens, Greece, 2010. - I. N. Borzov, S.A. Fayans, and E.L. Trykov, Nucl. Phys. A485, 335 (1995).
- N. V. Gnezdilov, I. N. Borzov, E. E. Saperstein, and S. V. Tolokonnikov, Phys. Rev. C 89, 034304 (2014).
- I.N. Borzov, Phys.Rev. C67, 025802 (2003)
Speaker: Ivan Borzov (NRC KI) - M. Agostini M., K. Altenmuller, S. Appel et al. for BOREXINO Collaboration
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107
FISSION FRAGMENTS DISTRIBUTION AND HEAVY NUCLEI NUCLEOSYNTHESIS.
The discovery of neutron star merger process and simultaneous observation of heavy elements registered for the first time [1] confirms the theoretical findings that neutron star merger scenario for the close binary is the main site for the r-process passing.
As it was shown for the first time in numerical calculations of the r-process [2], the fission in such a scenario became one of the main reaction channel for the heavy nuclei formation due to involvement of fission products into the r-process as secondary seed nuclei. More than that in such a scenario, leading to the initial conditions with big ratio of free neutrons to seeds, the role of fission products mass distribution became very important for the creation of second peak on the abundance curve. From the other hand the agreement of predicted abundances of second peak heavy nuclei with observations is the test for theoretical models of fission fragment mass distribution.
In the present report the influence of fission fragment mass distribution models and their parameters on the nucleosynthesis results of heavy nuclei in neutron-rich matter of jets, formed as a result of neutron stars merger, are discussed. We considered the fission fragment mass distributions, based on the FFDn [3] and KT-M [4] models, and have researched the dependence of predicted value of chemical elements abundances on the fission fragments mass distribution models used.
It was shown that fission fragments mass distribution models, with parameterization leading to mainly symmetrical fission gives better agreement with abundances observations for the second peak. Besides that the theoretical peak position coincides with observable one only for models, in which fission neutrons were taking into account. And the number of fission neutrons in these models for the neutron rich nuclei should be in times more than in fission of experimentally known nuclei. Under formation of heavy elements in the r-process the contribution of triple fission to the addition to binary one was also evaluated [5,6].The work was done under financial support of Russian Science Foundation (project № 21-12-00061).
- N.R.Tanvir et al. // The Astrophysical Journal Letters. 2017. V.848, P. L27.
- I.V.Panov, F.-K.Thielemann // Astronomy Letters. 2003. V.29, P.510.
- I.V.Panov, I.Yu.Korneev, F.-K.Thielemann // Astronomy Letters. 2008. V.34, P.189.
- T.Kodama, K.Takahashi // Nucl. Phys. A. 1975. V.239(3), P.489.
- A.V.Karpov // Phys. Rev. C. 2016. V.94. id. 064615.
- Yu.V.Pyatkov, D.V.Kamanin, A.A.Alexandrov et al. // Phys. Rev. C. 2017. V.96. id.064606.
Speaker: Igor Panov (ITEP) -
108
Some corrections to Fermi-functions and neutrino capture cross-sections
Neutrino capture cross-section, which depend on the incident-neutrino energy $E_{\nu}$, has the form:
$\sigma(E_{\nu}) = \frac{(G_F g_A)^2}{\pi c^3 \hbar^4} \int_{0}^{W - Q} W p_e F(Z, A, W) S(x) dx$
where $S(E)$ is the charge-exchange strength function, $G_F / (\hbar c)^3 = 1.1663787(6) \times 10^{-5}$ $GeV^{-2}$ is the weak coupling constant, $g_A = - 1.2723$ is the axial-vector constant and $F(Z, A, W)$ is the Fermi-function, which takes into account the Coulomb interaction between beta-particle and the daughter nucleus. The change in the Fermi-function is practically proportional to the change in the cross-section. Since the founding work of Fermi [1] which presented the Fermi-function for point-like nucleus there have been many works describing corrections to the Fermi-function including finite nuclear size, charge distribution, screening etc. One can see a good review of different types of them in [2].In this work we present the influence of finite nuclear size, screening etc. corrections to the Fermi-function and consequently to cross-section as an example of the $^{127}$I [3]. Particular attention is paid to the dependence of Fermi-function on the nuclear charge radius $R_C$ . Recent experimental results of isotopic dependence of the charge radii for K, Cu, Sn together with theoretical calculations based on the self-consistent theory of finite Fermi-systems with the Fayans density functional was taken into account [4], [5].
- E. Fermi, Z.Phys. 88, 161–177(1934).
- L. Hayen, et al., Rev.Mod.Phys. 90, 015008 (2018).
- Yu. S. Lutostansky, G. A. Koroteev, N.V. Klochkova, A.P. Osipenko, V.N. Tikhonov, and A.N. Fazliakhmetov, JETP Lett. 111, 603 (2020).
- E. E. Saperstein and S. V. Tolokonnikov, Phys. Atom. Nuclei 79, 1030–1066 (2016)
- I. N. Borzov and S. V. Tolokonnikov, Phys. Atom. Nuclei 83, 828–840 (2020).
Speaker: Almaz Fazliakhmetov (MIPT, INR RAS, NRC "Kurchatov Institute") -
109
BETA-DECAY RATE IS AN IMPORTANT FACTOR OF THE R-PROCESS HEAVY NUCLEI FORMATION.
More than the half of all nuclei heavier iron in nature are formed in the nucleosynthesis, supported by rapid neutron capture process, and the region where it has occurred lies close to neutron drip-line [1]. The nucleosynthesis rate of heavy nuclei in the r-process is defined both by the astrophysical scenario and beta-decay rates of heavy nuclei involved. Under speeding up or slowing down the nucleosynthesis wave movement into the region of more heavier nuclei, the trajectory of the r-process is changed as well as the position of the third peak on the abundance curve of heavy nuclei [2], that is pointing out on the complicated influence of the beta-decay model on nucleosynthesis.
Using the results of heavy nuclei abundances calculations in the r-process in the scenario of neutron stars merger the sensitivity of the results on input data was determined. The influence of different theoretical models of beta-decay on abundances of heavy nuclei was investigated.
In the nucleosynthesis calculations global beta-decay half-lives predictions based on different microscopic models [3, 4, 5] have been used. The calculations have confirmed the strong beta-decay model influence on heavy nuclei nucleosynthesis process. Comparison of the results have shown that dependence of average nucleosynthesis rate value on existed theoretical models of beta-decay is weak. But even the moderate change of the rate leads to the shift of platinum peak position in comparison with observations and strong discrepancy in abundances. All these results have shown that for reliable predictions of heavy nuclear abundances the more prominent microscopic models [6] are needed.The work was done under financial support of Russian Science Foundation (project № 21-12-00061).
- I.V. Panov // Astronomy Letters. 2003. V.29, P.163.
- I.V.Panov, Yu.S. Lutostansky // Physics of Atomic Nuclei. 2020. V.83, P.613.
- I.V.Panov, Yu.S. Lutostansky, F.-K. Thielemann // Nucl. Phys. A. 2016. V.947. P.1.
- P.Möller, B.Pfeiffer, K.-L.Kratz // Phys. Rev. C. 2003. V.67. 055802.
- T.Marketin, L.Huther, and G.Mart´ınez-Pinedo // Phys. Rev. C. 2016. V.93. 025805.
- I.N.Borzov // Physics of Atomic Nuclei. 2020. V.83. P.700.
Speaker: Igor Panov (ITEP) -
110
Sensitivity of liquid argon dark matter search experiments to core-collapse supernova neutrinos.
Future liquid-argon DarkSide-20k and ARGO detectors, designed for direct
dark matter search, will be sensitive also to core-collapse supernova
neutrinos, via coherent elastic neutrino-nucleus scattering.
Thanks to the low-energy threshold of ∼0.5~keVnr achievable via the
ionization channel, DarkSide-20k and ARGO have the potential to discover
supernova bursts throughout our galaxy and up to the Small Magellanic
Cloud, with sensitivity also to the neutronization burst.
The accuracies in the reconstruction of the average and total
neutrino energy in the different phases of the supernova burst,
as well as its time profile, taking into account the expected background
and the detector response, are reviewed.Speaker: Igor Machulin (NRC "Kurchatov Institute")
-
102
-
Poster session (Experimental and theoretical studies of the properties of atomic nuclei)Convener: Egor Zemlin (Saint Petersburg State University, Russia)
-
111
Nucleon density profiles and nucleus-nucleus interaction potential
One of the standard methods to construct the internuclear potential is the folding procedure. Consequently, the characteristics of the Coulomb barrier obtained by this procedure turn out to be sensitive to both the parametrization of the nucleon-nucleon interaction and the quality of the description of the nucleons distribution in nuclei [1,2]. In this report, the calculations are carried out for spherical even-even nuclei with $Z, N \ge 8$. Required nucleon density distribution is chosen as a Fermi-distribution. Special attention is paid to the correction of charge radius. The approximation most accurately describing experimental data is applied [3]. The dependency of the potential barrier localization from both diffuseness and half-density radius is considered. Gained nucleon density Fermi-distributions are compared with those obtained in Skyrme-Hartree-Fock approach.
- V. Zagrebaev et al., Phys. Part. Nucl. 38, 469 (2007).
- A. B. Migdal. The Theory of Finite Fermi-Systems and Properties of Atomic Nuclei, 2-nd ed. (Nauka, Moscow, 1983) [in Russian].
- I. Angeli et al., At. Data Nucl. Data Tables 99, 69 (2013).
Speaker: Mr Makar Simonov (Faculty of Physics, Lomonosov Moscow State University; Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research) -
112
Diffraction processes in elastic scattering of 16-О by medium nuclei
As one of the methods for the experimental detection of the multicluster structure of atomic nuclei, the authors proposed a method for expanding the experimental angular distributions of differential cross sections for elastic diffraction scattering into multicluster components [1-2]. Within the framework of the diffraction theory and under the assumption of total absorption inside the interaction sphere, the authors obtained expansions of the total amplitudes of the angular distributions of the differential cross sections for elastic scattering of 16-O, in particular, on 28-Si at energies of 20.83 MeV [3] and 240 MeV [4].
The experimental data are described within the framework of the theory of diffraction scattering as a superposition of wave functions on an absolutely black nucleus and on its absolutely black substructures (for example, alpha clusters) [2]. Figures 1 and 2 show the fitting results. Satisfactory agreement is seen between the theoretical curves and experimental data. In Figure 1, there is a discrepancy with theory in the range of back angles from 160 to 177 degrees. This is due to the limited applicability of this model, which, within the framework of this paradigm, does not take into account other nuclear phenomena. Thus, the interaction of 16-O ion beams with 28-Si revealed clumps of nuclear matter with characteristic radii of 1 fm and 0.5 fm. The analysis of the differential cross sections for elastic scattering of 16-O already at 40-Ca by this method has shown itself to be unsatisfactory, which speaks in favor of the "dissolution" of clusters in the mean nucleon field of the nucleus.
This research has been funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP09258978).- K.A. Gridnev et al., Bulletin of the Russian Academy of Sciences Physics 78(7), (2014)
- V.V. Dyachkov et al., Physics of Atomic Nuclei 83(12), (2020)
- M.C.Mermaz et al., J. PR C 29, 147 (1984)
- L.M. Fonseca et al., J. PR C 100, 014604 (2019)
Speaker: Dr Vyacheslav Dyachkov (al-Farabi Kazakh National University) -
113
Alpha decay characteristics of superheavy elements
Superheavy elements are of great interest from the point of view of fundamental nuclear physics. The most important task of this direction is not only the discovery of new elements, but also the synthesis of the maximum number of isotopes of each element, which makes it possible to consider the change in the physical properties of heavy nuclei both with a change in the number of protons and with an increase in the number of neutrons. An important feature of the region of superheavy nuclei is the predominant decay with the emission of an alpha particle. This feature is at the heart of modern methods for registration of new elements, so prediction of the alpha decay characteristics of unknown elements is very important [1].
The alpha decay energy of an unknown nucleus can be obtained by evaluating the binding energies of the corresponding nuclei. Successful phenomenological approach application to binding energy predictions for nuclei with a proton number $Z$ up to 106 based on the residual np-interaction formula was demonstrated in our previous work [2]. The report presents the further development of the approach. The prediction method is expanded by taking into account experimental alpha decay energy. This modification made it possible to overcome the limitations and carry out calculations in the field of heavier nuclei. New results obtained using the latest experimental data compilation AME2020 [3]. Comparison with other model predictions is presented.
1. Yu.Ts. Oganessian et al., Phys. Scr. 92, 02300 (2017).
2. E.V. Vladimirova et al., Int. J. Mod. Phys. E 30, 2150025 (2021).
3. Meng Wang et al., Chin. Phys. C 45, 030003 (2021).Speaker: Ivan Mostakov (Lomonosov Moscow State University) -
114
Study of ground states of 13,14C, 13,14N, 14O nuclei by Feynman's continual integrals
The ground states of ${}^{13,14}$C, ${}^{13,14}$N, ${}^{14}$O nuclei were studied in two complementary few-body models. In first model the studied isotopes were considered as cluster nuclei with following configurations: ${}^{13}$C ($3\alpha + n$ ), ${}^{14}$C ($3\alpha + 2n$), ${}^{13}$N ($3\alpha + p$), ${}^{14}$N ($3\alpha + n + p$), ${}^{14}$O ($3\alpha + 2p$). In second model the studied isotopes were considered as systems consisting from nuclear core ${}^{12}$C and one or two valence nucleons. The wave functions and energies of these few-body systems were calculated by Feynman’s continual integrals method in Euclidean time [1–3]. The algorithm of parallel calculations was implemented in C++ programming language using NVIDIA CUDA technology [4]. Calculations were performed on the NVIDIA Tesla K40 accelerator installed within the heterogeneous cluster of the Laboratory of Information Technologies, Joint Institute for Nuclear Research, Dubna [5]. Results of the few-body model were compared with results of the shell model of deformed nuclei [6, 7].
References
1. Feynman R.P. and Hibbs A.R. Quantum Mechanics and Path Integrals (McGraw-Hill, New York, 1965).
2. Shuryak E.V. and Zhirov O.V. // Nucl. Phys. B. 1984. V.242. P.393.
3. Samarin V.V. and Naumenko M.A. // Phys. Atom. Nucl. 2017. V.80. P.877.
4. Naumenko M.A. and Samarin V.V. // Supercomp. Front. Innov. 2016. V.3. P.80.
5. http://hybrilit.jinr.ru.
6. Samarin V.V. // Phys. Atom. Nucl. 2010. V.73. P. 1416.
7. Samarin V.V. // Phys. Atom. Nucl. 2015. V.78. P. 128.Speaker: Viacheslav Samarin (Joint Institute for Nuclear Research) -
115
Collisional quenching of the pionic helium long-lived states
About 60 years ago G. Condo [1] suggested a possible existence of long-lived states of pionic and kaonic helium atoms
($\pi^- \mathrm{He}^+$ and $K^- \mathrm{He}^+$) in order to explain that a some fraction (about 2%) of the negative mesons decays after the stopping in the helium target, contrary to the hydrogen target.
A direct experimental evidence of the similar states was obtained by the observation of the time spectra of the products of $K^-$ decay and of the products of $K^-$ and $\pi^-$ nuclear absorptions.
The discovery of the similar metastable states of antiprotonic helium [2] opened a whole new area of the study that bring an extensive information on the exotic atoms and fundamental antiproton characteristics [3,4].
Recently laser-induced transition in pionic helium was observed for the first time [5]. A possibility of the further precision laser spectroscopy of this system depends, in particular, on the stability of the states against the quenching by collisions with the medium atoms. We consider Stark transitions between the highly excited states in the collisions
$(\pi^- \mathrm{He}^+)^*_{nL} + \mathrm{He} \rightarrow (\pi^- \mathrm{He}^+)^*_{nL'} + \mathrm{He} \quad (L'\neq L)$,
which can be expected as the most probable due to a small difference of the inner initial and final energies.
The cross sections and transition rates are calculated by solving the close coupling equations involving the different $L$ at a fixed $n$. In order to obtain an interaction between the colliding systems we calculate the Potential Energy Surface (PES) of the three electrons in the field of three heavy particles (two $\alpha$-particles and $\pi^-$). (Similar PES calculations were done in the paper [6], however no results for the potential were published.)Dependencies of the Stark transition cross sections on the quantum numbers of the states and on the initial kinetic energy will be presented in the talk.
1. G.T. Condo, Phys. Lett. 9 (1964) 65.
2. M. Iwasaki, S.N. Nakamura, K. Shigaki et al. Phys. Rev. Lett. 67 (1991) 1246.
3. T. Yamazaki, N. Morita, R.S. Hayano, E. Widmann, J. Eades, Phys. Reports 366 (2002) 183–329.
4. R.S. Hayano, M. Hori, D. Horva'th, E. Widmann, Rep. Prog. Phys. 70 (2007) 1995-2065.
5. M. Hori, H. Aghai-Khozani, A. Sótér, A. Dax, D. Barna, Nature 581 (2020) 37.
6. B. Obreshkov and D. Bakalov, Phys. Rev. A 93 (2016) 062505.Speakers: Dr Grigoriy Korenman (MSU SINP), Sergey Yudin (MSU) -
116
THE ALIGNMENT OF THE ${}^{16}O$($3^-$; 6.131 MeV) NUCLEUS FORMED IN SOME NUCLEAR REACTIONS AT $E_x\approx 7.5$ MeV/NUCLEON
Experimental and calculated the $F_2(\theta_y)$ and $F_4(\theta_y)$ alignment angular dependences of the ${}^{16}O$ nucleus in the excited state $3^-$ (6.131 MeV), formed in the reactions ${}^{16}O(\alpha,\alpha)^{16}O$, ${}^{14}N(\alpha, d)^{16}O$, ${}^{15}N(\alpha, t)^{16}O$ and ${}^{19}F(p,\alpha)^{16}O$ at energies $E_\alpha = 30.3$ MeV and $E_p = 7.5$ MeV are presented. The orientation parameters $F_k$ ($k =1,\dots,2J, |F_k| \le 1$) are polynomials in the mean values of the powers $\langle J_z\rangle$ and are included in the expression for the interaction energy of nuclei with an electromagnetic field [1]. The parameter of the dipole orientation $F_1$ is called polarization, and the quadrupole $F_2$ is the alignment of the nuclei. Since the method of angular correlations used in this work makes it possible to experimentally determine only even components, we consider the parameters of the quadrupole $F_2$ and hexadecapole $F_4$ orientations. In the case of an isotropic spin distribution, the alignment is zero. The maximum value of the parameters is achieved at the maximum value of the spin projection $M=J$ onto the quantization axis:
$F_2=\frac{2J+1}{\sqrt{5}}\sqrt{\frac{(J+1)(2J+3)}{J(2J-1)}} T_{20},$ $F_4=\frac{2J+1}{6}\sqrt{\frac{(2J+3)(2J+2)(2J+4)(2J+5)}{J(J-1)(2J-1)(2J-3)}} T_{40} ,$ $T_{k0}=\frac{1}{2J+1}\frac{\rho_{k0}(\theta_y)}{\rho_{00}(\theta_y)},$
where $\rho_{k0}(\theta_y)$ is the spin tensor component of the nucleus density matrix.
Experimental information was obtained on the basis of previously retrieved [2-5] spin-tensors $\rho_{kK}(\theta_y)$ density matrices of the ${}^{16}O$ nucleus ($3^-$; 6.131 MeV) by measuring of the angular particle-gamma correlations.
The experimental orientation parameters are compared with the calculated ones under the assumption of the mechanisms of stripping or pickup a nucleon cluster by the coupled channel method (FRESCO code [6]) and a compound nucleus (TALYS code [7]). The features of the behavior of the orientation parameters of the ${}^{16}O$ nucleus ($3^-$; 6.131 MeV) formed in various reactions are discussed and compared.- G.R. Khutsishvili. Uspekhi Fizicheskikh Nauk. V.53, P. 381 (1954).
- A.V. Ignatenko et al. Izvestiya RAN. Seriya Fizicheskaya. V.58, P. 188 (1994).
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- A.V. Ignatenko et al. Izvestiya RAN. Seriya Fizicheskaya. V. 66, P. 1507 (2002).
- A.V. Ignatenko et al. Izvestiya RAN. Seriya Fizicheskaya. V. 60, P. 189 (1996).
- I. J. Thompson. Comp. Phys. Rep. 7, 167 (1988); http://www.fresko.org.uk/.
- A.J. Koning, S. Hilaire, and M. C. Duijvestijn. TALYS: AIP Conf. Proc. 769, 1154 (2005); https://tendl. web.psi.ch/tendl_2019/talys.html.
Speaker: Nataliia Zelenskaya (M.V. Lomonosov Moscow State University) -
117
CALCULATIONS OF THE OCTOPOLE DEFORMATION OF RADIUM AND THORIUM ISOTOPES IN THE HARTREE-FOCK-BOGOLYUBOV APPROXIMATION WITH SKYRME FORCES
In the Hartree-Fock-Bogolyubov (HFB) approximation, assuming the axial symmetry of nuclei with Skyrme forces (SkM* and SLy4), we calculated the properties of Ra and Th isotopes with A = 218 – 230. These isotopes are currently intensively studied for the presence of octupole deformation in them. In addition, HFB calculations of the properties of Ra and Th isotopes were carried out in the vicinity of the neutron drip line with A = 280 – 290. We used the computer code HFBTHO v2.00d [1] in our calculations. Pairing of nucleons in nuclei is described by density-dependent zero-range pairing forces with different sets of pairing force constants. In the calculations, we used the constrained conditions on the parameters of the quadrupole $β_2$ and octupole $β_3$ deformations of nuclei and refining calculations without the constrained conditions in the vicinity of the minimum of the dependence of the total nuclear energy $E(β_2, β_3$) on $β_2$ and $β_3$. It is shown that for the considered isotopes Ra and Th, the value of $β_3$ nuclei strongly depends on the choice of the parameters of the nucleon pairing force. The preferred values of the constants of the pairing forces of neutrons and protons for the considered isotopes Ra and Th were selected from a comparison of the calculated values of the proton and neutron energy gaps with their values calculated from the even-odd differences in the masses of neighboring nuclei. The increase in the pairing strength leads to a decrease or complete disappearance of $β_2$ and $β_3$ in the considered isotopes Ra and Th.
Speaker: Vyacheslav Tarasov (Nat. Sci. Center "Kharkov Institute of Physics & Technology") -
118
STRUCTURE OF LEVELS AND ELECTROMAGNETIC TRANSITION RATES IN ODD-ODD NUCLEI CLOSE TO DOUBLY-MAGIC NEUTRON DEFICIENT $^{100}$Sn
In our previous papers, we extensively studied odd-odd nuclei adjacent to doubly
magical stable nuclide $^{208}$Pb, as well as to also doubly magical neutron excess
$^{132}$Sn. To date, some experimental information has emerged also about the
properties of such nuclei in the vicinity of an extremely neutron deficient and
also doubly magical $^{100}$Sn. In our calculations of odd-odd nuclei close to
$^{100}$Sn, we applied random phase
approximation and multi-particle shell model, both based on the phenomenological
nuclear potential [1] and effective two-body interaction [2], which parameters were
defined by us before. The subject of our interest were $^{98}_{49}$In$_{49}$,
$^{100}_{49}$In$_{51}$, $^{98}_{47}$Ag$_{51}$ and $^{94}_{45}$Rh$_{49}$. In these
nuclei we determined energy spectra and $E2, M1$ transition rates. Effective
transition operators were also defined by us before [3], and they successfully
described $E2$ and $M1$ transitions in nuclei close to $^{208}$Pb and $^{132}$Sn.
In particular, the values of proton and neutron effective charges were $e_p = 1.6|e|$
and $e_n = 0.9|e|$. In our case, the value of $e_p \approx 1.6|e|$ was also obtained
by us by using the experimental $T_{1/2}$ values of the $8^{+}_{1} \to 6^{+}_{1}$
and $6^{+}_{1} \to 4^{+}_{1}$ transitions in $^{98}_{48}$Cd$_{50}$ [4], as well as our
RPA calculation for these cases. However, the energy of an analogous $6^{+}_{1} \to 4^{+}_{1}$ transition and its half-life in $^{102}_{50}$Sn$_{52}$ are known with
great uncertainty [4, 5] and thus the value of neutron effective charge in nuclei
close to$^{100}$Sn is also very uncertain [5]: $e_n = 2.3(+0.6 -0.2)|e|$. Such a
large value of neutron effective charge is a subject of discussions. Here, we defined
the values of $e_p$ and $e_n$ from the joint description of the $4^{+}_{1} \to 6^{+}_{1}(gr.st.)$ and $2^{+}_{1} \to 4^{+}_{1}(gr.st.)$ transitions in $^{98}$Ag
and $^{94}$Rh. The result is $e_p \approx 1.6$ and $e_n \approx 2.8$. Mention that
the obtained by us value of $e_n$ agrees with the experimental results [6, 7],
considered together with theoretical calculations performed by us for the
$6^{+}_{1} \to 4^{+}_{1}$ transition in $^{102}$Sn [2].- V. I. Isakov et al., Eur. Phys. J. A {\bf14}, 29 (2002).
- V. I. Isakov, Phys. At. Nucl. {\bf76}, No 7, 828 (2013).
- S. A. Artamonov, et al., Sov. J. Nucl. Phys. {\bf36}, No 4, 486 (1982).
- https://www-nds.bnl.gov/ensdf/
- M. Lipoglav$\breve{s}$ek et al., Phys. Lett. B {\bf440}, 246 (1998).
- T. Faestermann, {\em Spectroscopy of N $\sim$ Z Nuclei:
$^{100}$Sn and Neighbours}, https://indico.ific.\uv.es/event/349/contributions/6172/
attachments/4036/4532/Faestermann.pdf, 24 (2011). - M. G$\acute{o}$rska, {\em Recent results in the region of $^{100}$Sn}, https://indico.in2p3.fr/
event/12970/\contriburions/12367/attachments/10498/13010/SSNET$\_$gorska$\_$2016$\_$2.pdf, 36 (2016).
Speaker: Vadim Isakov (PNPI NRC KI St.-Petersburg) -
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THE INFORMATION SYSTEM MASCA FOR CALCULATION AND GRAPHICAL REPRESENTATION OF ATOMIC MASSES, BINDING ENERGIES OF NUCLEI, ENERGIES OF SEPARATIONS AND NUCLEAR DECAYS, ENERGY THRESHOLDS OF NUCLEAR REACTIONS
The database MASCA contains the evaluated atomic mass values of AME 2020 [1]. The program-interface to it allows getting the recommended values of atomic mass and nuclear binding energy for a given nuclide, as well as the calculated values of the energies of the main nuclear decays; the energies of proton and neutron separations; nuclear pairing energies; energy thresholds of nuclear reactions caused by protons, neutrons, deuterons, gamma quanta, etc. The covariance matrix is used to calculate the uncertainties of the derived quantities.
For the selected group of nuclides and the selected mass characteristics, a table of their values and a graphical representation of their changes for any of the three parameters $A$, $Z$, $N$ can be got [2]. The resulting tables and graphs can be saved and used in applications. The database MASCA and the program-interface to it have passed state registration [3] and are free distributed on request.
Using databases of different years under the same shell, AME 2012, AME 2016 and AME 2020, allows us to compare them quantitatively and study the dynamics of our knowledge in this area.
The information system MASCA can be used for educational purposes when studying the basics of nuclear physics.- W.J.Huang et al., Chinese Phys. C45, 030002 (2021).
- L.P.Kabina et al. PNPI preprint 3053, Gatchina, 2021, 20 p.
- L.P.Kabina et al. The certificate 2017620770 of state registration of the database, 2017; The certificate 2017615009 of state registration of the code, 2017.
Speaker: I.A. Mitropolsky (PNPI of NRC Kurchatov Institute)
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PlenaryConveners: Andrianov Vladimir (Saint Petersburg State University, Russia), Alexander Andrianov (Saint Petersburg State University, Russia)
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Highlights from the STAR experiment
One of the main aims of the relativistic nuclear physics is an exploration of the properties of hot and dense nuclear matter produced in heavy-ion collisions. The Relativistic Heavy Ion Collider (RHIC) provides a unique opportunity to map the QCD phase diagram colliding different nuclei species and varying the energy of collisions. The second phase of the Beam Energy Scan (BES) program at RHIC covers a broad energy range for gold-gold collisions $\sqrt{s_{NN}}$= 7.7−27 GeV. The Fixed-target Program (FXT) extends collision energy range available for the analysis down to $\sqrt{s_{NN}}$= 3.0 GeV.
In this talk, we will present recent results from the STAR experiment and the future plans.
Speaker: Grigory Nigmatkulov (National Research Nuclear University MEPhI) -
121
Overview of recent measurements by NA61/SHINE at the CERN SPS
NA61/SHINE at the CERN SPS performed a unique two-dimensional scan of system size and collision energy with a goal to search for a critical point of the strongly interacting matter and to explore properties of matter at the onset of deconfinement. This talk will cover highlights from recent measurements in p+p, Be+Be, Ar+Sc, and Pb+Pb reactions. The results concern hadron yields and their ratios, charged hadron directed and elliptic flow, proton intermittency, electromagnetic effects, higher-order moments of multiplicity and net-charge fluctuations. A comparison with model predictions and data from other experiments in the SPS energy range will be also shown. The physics case and status of the ongoing upgrade of the NA61/SHINE facility will be discussed.
Speaker: Evgeny Kashirin (National Research Nuclear University MEPhI (RU)) -
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PHENIX overview
Relativistic heavy ion collisions have been considered as a unique way to create and study the quark-gluon plasma (QGP) where the quarks and gluons are de-confined. PHENIX, which stands for the Pioneering High Energy Nuclear Interaction eXperiment, was operated for 16 years until 2016, and has been producing physics results from the data taken until then. Over this period, collision data were recorded spanning nine collision energies from 7.7 GeV to 510 GeV, and nine collision systems using Au, U, Cu, Al, p, and d. PHENIX is capable of detecting a wide variety of particles such as leptons, photons, light and heavy hadrons, with which many observables including but not limited to jets, particle correlations, single hadron spectra and flow have been measured and studied. Much progress is still being made in analysis of the data we took.
In this overview PHENIX talk, we will report the latest results from PHENIX, both on soft and hard probes from small to large systems.
Speaker: Maya Shimomura (Nara Women's University (JP)) -
10:45 AM
Coffee break
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The sPHENIX experiment at RHIC
The sPHENIX experiment at RHIC is currently under construction and on schedule for first data in early 2023. Built around the excellent BaBar superconducting solenoid, the central detector consists of a silicon pixel vertexer adapted from the ALICE ITS design, a silicon strip detector with single event timing resolution, a compact TPC, novel EM calorimetry, and two layers of hadronic calorimetry. The hybrid streaming/triggered readout of the detector enables full exploitation of the luminosity provided by RHIC. The experiment will deliver unprecedented data sets for a wide variety of multi-scale measurements at RHIC, including studies of jet modification, upsilon suppression and open heavy flavor production in p+p, p+Au and Au+Au collisions. The talk will describe the readiness of the experiment for operations, present current projections of key jet and heavy flavor measurements, and discuss their potential scientific impact.
Speaker: Marzia Rosati (Iowa State University (US)) -
124
Belle II: status and prospects
The Belle II experiment at the SuperKEKB energy-asymmetric e$^+$e$^−$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The target luminosity of the machine is 6×$10^{35}$ cm$^{−2}$s$^{−1}$ and the Belle II experiment aims to record 50 ab$^{−1}$ of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the matrix elements and their phases, with unprecedented precision and explore flavor physics with B and charmed mesons, and τ leptons. Belle II has also a unique capability to search for low mass dark matter and low mass mediators. We also expect exciting results in quarkonium physics with Belle II. In this presentation, we will review the status of the Belle II detector, the results of the planned measurements with the full available Belle II data set, and the prospects for physics at Belle II.
Speaker: Peter Lewis (University of Hawaii) -
125
Applying Heavy-Ion Storage Rings for Precision Experiments at the Intersection of Atomic, Nuclear and Astro-Physics
The storage of freshly produced radioactive particles in a storage ring is a straightforward way to achieve the most efficient use of such rare species as it allows for using the same rare ion multiple times. Employing storage rings for precision physics experiments with highly-charged ions (HCI) at the intersection of atomic, nuclear, plasma and astrophysics is a rapidly developing field of research.
Until very recently, there were only two accelerator laboratories, GSI Helmholtz Center in Darmstadt, Germany (GSI) and Institute of Modern Physics in Lanzhou, China (IMP), operating heavy-ion storage rings coupled to radioactive-ion production facilities. The experimental storage ring ESR at GSI and the experimental cooler-storage ring CSRe at IMP offer beams at energies of several hundred A MeV. The ESR is capable to slow down ion beams to as low as 4 A MeV ($\beta$=0.1). Beam manipulations like deceleration, bunching, accumulation, and especially the efficient beam cooling as well as the sophisticated experimental equipment make rings versatile instruments. The number of physics cases is enormous. The focus here will be on the most recent highlight results achieved within FAIR-Phase 0 research program at the ESR.
First, the measurement of the bound-state beta decay of fully-ionized $^{205}$Tl was proposed about 35 years ago and was finally accomplished in 2020. Here, the ESR is presently the only instrument enabling precision studies of decays of HCIs. Such decays reflect atom-nucleus interactions and are relevant for atomic physics and nuclear structure as well as for nucleosynthesis in stellar objects.
Second, the efficient deceleration of beams to low energies enabled studies of proton-induced reactions in the vicinity of the Gamow window of the p-process nucleosynthesis. Proton capture reaction on short-lived $^{118}$Te was attempted in 2020 in the ESR. Here, the well-known atomic charge exchange cross-sections are used to constrain poorly known nuclear reaction rates.
The performed experiments will be put in the context of the present research programs at GSI/FAIR and in a broader, worldwide context, where, thanks to fascinating results obtained at the presently operating storage rings, a number of new exciting projects is planned. Experimental opportunities are being now dramatically enhanced through construction of dedicated low-energy storage rings, which enable stored and cooled secondary HCIs in previously inaccessible low-energy range. The first such facility, CRYRING, has been employed at GSI for first experiments with decelerated beams of HCIs from the ESR.
Thanks to the fascinating results obtained at the ESR and the CSRe as well as to versatile experimental opportunities, there is now an increased attention to the research with ion-storage rings worldwide. An isochronous storage ring for mass measurements, R3, has just been commissioned at RIKEN. Dedicated ring facilities are proposed for ISOLDE at CERN, TRIUMF, FRIB, LANL, and JINR.Speaker: Yuri A. Litvinov (GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
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12:45 PM
Lunch break
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Section 1. Experimental and theoretical studies of the properties of atomic nucleiConvener: Tatiana Lazareva (St Petersburg State University (RU))
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Limiting temperature of nuclei within effective relativistic mean-field theory
The recent detection of the gravitational wave GW170817, accompanied by a $\gamma$-ray burst and electromagnetic afterglow from the merger of neutron-star binary, has opened a new era of nuclear astrophysics. With neutron stars as a predominant laboratory for testing infinite nuclear matter, it has become easy to fine-tune the equation of the state (EoS) of nuclear matter using observational constraints. The nuclear matter EoS is of utmost importance for calculating infinite matter properties besides giving reasonable input about finite nuclei. Understanding the ground state of nuclear matter is essential, but its behaviour at finite temperature is equally significant for various terrestrial and astrophysical processes such as multi-fragmentation in nucleus and supernova explosion [1]. The estimation of limiting temperature $T_l$ (the maximum temperature that a nucleus can sustain) of a nucleus is extremely important to extract relevant nuclear properties. The analysis of this limiting temperature helps to understand the qualitative behaviour of liquid-gas phase transition in an excited nucleus and astrophysical processes such as the structure of proto-neutron star and supernova explosion etc.
We have used the effective relativistic mean-field theory (E-RMF) to analyze the limiting temperature of the excited nucleus using several parameter sets which satisfy various observational constraint of EoS [2]. We add the Coulomb interaction and surface tension due to the finite size effect of the nucleus and solve the coexistence equation for phase equilibrium. Surface tension is a function of the critical temperature ($T_c$) of infinite matter [3], which is not a good constraint variable [4], unlike other infinite nuclear matter saturation properties. Therefore, we look for the possible correlation of the limiting temperature of nuclei with zero and critical temperature properties. These correlations might help to understand observables that could not be measured directly in experiments.
[1] Vishal Parmar et al., Phys. Rev. C 103 055817 (2021).
[2] M. Dutra et al., Phys. Rev. C 90 055203 (2014).
[3] S. S. Avancini et al., Phys. Rev. C 78 015802 (2008).
[4] Vishal Parmar et al., J. Phys. G: Nucl. Part. Phys. 48 025108 (2021).Speaker: Vishal Parmar (Thapar Institute of Engineering and Technology) -
127
Convergence of calculations in oscillator basis
We study general convergence trends of binding energy calculations in oscillator basis depending on two basis parameters, the oscillator frequency, $\hbar\Omega$, and maximal oscillator quanta, $N$. We propose and test a new method which suggests extending the Hamiltonian matrix by the kinetic energy matrix elements. We study also convergence of calculations with smoothed potential matrix elements [1].
We use the SS-HORSE (single-state harmonic-oscillator representation of scattering equations) approach [2] extended to the case of bound states [3]. Within this method, we extract the $S$ matrix from the results of variational calculations with oscillator basis and locate the $S$-matrix poles associated with bound states. The respective binding energies improve the variational results and provide an extrapolation of the variational binding energies to the infinite basis space. A great advantage of our approach as compared with other extrapolation techniques suggested in current literature [4–6] is that it makes possible to calculate also asymptotic normalization constants.
References:
- J. Révai, M. Sotona and J. Žofka, J. Phys. G 11, 745 (1985).
- A. M. Shirokov, A. I. Mazur, I. A. Mazur and J. P. Vary, Phys. Rev. C 94, 064320 (2016).
- A. M. Shirokov, V. A. Kulikov and A. I. Mazur, Phys. At. Nucl. 82, 285 (2019).
- Yu. A. Lurie and A. M. Shirokov, Ann. Phys. (NY), 312, 284 (2004).
- P. Maris, J. P. Vary and A. M. Shirokov, Phys. Rev. C. 79, 014308 (2009).
- S. A. Coon, M. I. Avetian, M. K. G. Kruse, U. van Kolck, P. Maris and J. P. Vary, Phys. Rev. C. 86, 054002 (2012).
- R. J. Furnstahl, G. Hagen and T. Papenbrock, Phys. Rev. C. 86, 031301(R) (2012).
Speaker: Vasily Kulikov (Lomonosov Moscow State University) -
128
Z(4)-DDM: A γ-rigid solution of the Bohr Hamiltonian with Davidson potential for β and γ = 30°
In this work we modify the Davydov-Chaban Hamiltonian describing the collective motion of $\gamma$-rigid atomic nuclei by allowing the mass to depend on the nuclear deformation. We construct Z(4)-DDM (Deformation-Dependent Mass) model by considering the Davidson potential, and solve the problem by techniques of asymptotic iteration method (AIM). We compare the results of the calculated spectra and $B(E2)$ transition rates for series of $^{108-116}$Pd and $^{190-198}$Pt isotopes with experimental data as well as with other theoretical models. Exact analytical expressions are derived for spectra and normalized wave functions of Davidson potential. The obtained results show an overall agreement with the experimental data and an important improvement in respect to other models. Prediction of a new candidate nucleus for triaxial symmetry is made.
Speaker: Dr Alaaeddine Lahbas (ESMaR, Department of Physics, Faculty of Sciences, Mohammed V University in Rabat) -
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ON THE TRUE AND FICTITIOUS ENHANCEMENTS OF THE FUNDAMENTAL SYMMETRY BREAKING EFFECTS
All the enhancements of the P-violation effects in γ-transitions between the compound-nucleus states were analyzed in the classical paper [1] by I.S. Shapiro. The source of these effects is the weak interaction $V_W$ leading to the fact that the wave function $\psi$ of this state contains, besides the wave function of a definite parity $\psi_1$ , the small admixture of the opposite parity state $\psi_2$:
$$\psi=\psi_1+c\psi_2\hspace{2cm}(1)$$ The effect is defined by the ratio of the P-forbidden transition normalized by the total transition value: $$R=\frac{c(A_a\cdot A_f)}{(A_a+cA_f)^2}\approx\frac{cA_f}{A_a}\equiv\frac{n}{d}\hspace{2cm}(2)$$ Here $A_a$ and $A_f$ are the amplitudes of the P-allowed and P-forbidden transitions. The review [1] indicates 3 types of enhancement: 1) kinematical enhancement, 2) structural enhancement and 3) dynamical enhancement. The kinematical enhancement appears when the allowed transition is the magnetic one which is smaller than the forbidden electric of the same multipolarity by the factor $(v/c)\approx10$. The structural enhancement appears when the allowed transition amplitude comes to be unusually small due to some suppression caused by the structure of the initial and final states. One should point that both the kinematical and structural enhancements arise because of the decrease of the denominator $d$ in Eq. (2). Only the dynamical enhancement is caused by the increase of the admixture coefficient: $$c=\frac{<\psi_1|V_w|\psi_2>}{E_1-E_2}= \frac{v_P}{D}$$ in the numerator $n$ of (2). Here $v_P$ is the weak interaction matrix element, while the enhancement of the admixture for the high-lying exited states is caused by their strongly decreased level spacing. It is assumed that the largest magnitude of the symmetry-breaking effect allows to measure it with the largest accuracy (i. e. with the smallest relative error). This assumption is shown to be often misleading. Indeed, the experimentally measured value (2) is the ratio of the normally distributed numbers of numerators $n$ to denominators $d$. Taking their absolute errors to be σ and neglecting the correlation between them, one obtains for the relative error of the measured effect: $$\frac{\sigma_R}{R}\approx\sqrt{\frac{\sigma^2}{n^2}+\frac{\sigma^2}{d^2}}$$ We see that the dynamical enhancement of $n$ decreases the relative error and indeed leads to the enhanced accuracy of the effect’s measurement. However, the other two enhancements lead only to the slight increase of the relative error and to the poorer accuracy of the effect’s measuring. Usefulness of the relative error approach to transmission measurements is also discussed.References:
1. I.S.Shapiro, Sov. Phys.Uspekhi. 95, 647 (1968).Speaker: Prof. Vadim Bunakov (Petersburg Nuclear Physics Institute, National Research Center Kurchatov Institute, Gatchina) -
3:10 PM
Coffee break
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New mass evaluation and its implication for the neutron-rich nucleosynthesis product yield
Estimates for experimentally unknown nuclear masses are obtained by a phenomenological approach based on a local mass relation for the residual neutron-proton interaction. The local mass relations method provides both high accuracy of isotope mass predictions and mathematical simplicity of calculations [1, 2]. Results based on different databases AME2012-2020 [3] are presented. Neutron-rich isotopes in the r-process region are considered in detail.
The rates of neutron capture reactions at temperatures of 0.1-10 GK are calculated using the TALYS program [4] with the obtained mass estimates. The resulting rates are compared with calculations based on other mass prediction approaches. The resulting rates are also applied to calculate the r-process products yield in standard scenarios using the SkyNet library [5].
The results presented in this work demonstrate sensitivity of nucleosynthesis calculations to nuclear characteristics and neutron dripline localization.- J. Janecke et al., At. Data Nucl. Data Tables 39, 265 (1988).
- E.V. Vladimirova et al., Int. J. Mod. Phys. E 30, 2150025 (2021).
- Meng Wang et al., Chin. Phys. C 45, 030003 (2021).
- A.J. Koning et al., Nucl. Data Sheets 1, 155 (2019).
- J. Lippuner, L.F. Roberts, ApJS. 1, 233 (2017).
Speaker: Elena Vladimirova (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State) -
131
The role of spin-spin forces in calculations of transition probabilities between the first one-phonon states.
The self-consistent method for studying second-order anharmonic effects, within the framework of many-body quantum theory, is used for the first time to investigate the role of spin-spin forces in the probabilities of transitions between low-lying one-phonon states. Our approach includes accounting for: 1) self-consistency between the mean field and effective interaction based on the use of the energy density functional method with the proven parameters of Fayans functional DF3-a [1], 2) three-quasiparticle correlations in the ground state, 3) nuclear polarizability effects and 4) spin-spin interactions. E1-transitions between one-phonon 3-1 and 2+1 states in semimagic tin isotopes were studied. Good agreement with experiment [2] was obtained. It is shown that three-quasiparticle correlations in the ground state make a significant contribution to the value under study, as in our previous calculations for the EL transitions between first 3- and 2+ states in magic nuclei [3]. The specificity of this problem in nuclei with pairing and the effects of the spin components of the phonon creation amplitude are considered.
- S. V. Tolokonnikov, E. E. Saperstein, Phys. Atom.Nucl. 73, 1684 (2010).
- L. I. Govor, A. M. Demidov, O. K. Zhuravlev, et al., Sov. J. Nucl. Phys. 54, 196 (1991).
- S. P. Kamerdzhiev, D. F. Voitenkov, E. E. Sapershtein, S. V. Tolokonnikov, and M. I. Shitov, JETP Lett. 106, 139 (2017).
Speaker: Mr Mikhail Shitov (National Research Center Kurchatov Institute, Moscow, Russia) -
132
Effect of tensor correlations on the Gamov-Teller strength distribution in closed-shell parent nuclei
The effect is studied within a properly modified version of the continuum-random-phase-approximation (cRPA). Numerical results are obtained for the Gamow-Teller (GT) strength distribution in $^{208}Bi$. For this distribution, the experimental data concerned with the main-peak energy and the respective fraction of the Ikeda sum rule ($x_{peak}^{(-)}$) 1, and also the low-energy part distribution (total fraction $x_<^{(-)}$) [2] are available. Within the study, a realistic partially self-consistent phenomenological mean field (with parameters taken from independent data) and the spin-isovector component of Landau-Migdal forces (with the dimensionless strength g’) are exploited. In various calculations of the GT strength distribution (some results are shown in the Table), the parameter g’ is adjusted to reproduce the observed main-peak energy. There are two sources of considered tensor correlations (the latter mean a mixture of GT and respective $1^{+}$ spin-quadrupole excitations): (i) the mean-field spin-orbit term, and (ii) the appropriate component of tensor forces. Correlations of the first type are taken into account within the so-called non-symmetric version of cRPA. The corresponding equations can be found in Ref. [3]. These equations are directly extended by inclusion of the related contact tensor forces (with dimensionless strength $g_t^{'}$ ). The separable tensor forces are exploited in Ref. [4].
The calculation results obtained for various $g_t^{'}$ values (a part of results is given in the Table, where the total fraction $x_{tot}^{(-)}$ evaluated for the excitation energy interval 0-70 MeV is also shown) allow us to conclude: (i) the effect of definitely existing tensor correlations of the first type is weak; (ii) accounting for second-type correlations seems questionable and needs further consideration.
This work was supported in part by the Russian Foundation for Basic Research under grant no. 19-02-00660.
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H. Akimune et al., Phys. Rev. C 52, 604 (1995).
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A. Krasznahorkay et al., Phys. Rev. C 64, 067302 (2001).
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M. G. Urin, “Relaxation of Nuclear Excitations“. Energoatomisdat, Moscow, 1991 (in Russian).
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A. P. Severyukhin and H. Sagawa, Prog. Theor. Exp. Phys. 103D03 (2013).
Speaker: Vladimir Bondarenko (Shubnikov Institute of Crystallography Russian Academy of Scien) -
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133
NUCLEAR RADII SYSTEMATICS BASED ON AN ARTIFICIAL NEURAL NETWORK WITH FUZZY LOGIC
This paper develops the first experience of using a fuzzy hybrid network model for the systematics of nuclear radii [1]. The root-mean-square charge radii of atomic nuclei measured by different methods are collected in the NuRa database [2]. A good result for the radii of all nuclei is given by the parametrization (the smooth curve in Fig.1).)
$R=(r_0+r_1 A^{1/3})\cdot A^{1/3}$ , if $r_0=1.07$ fm, $r_1=-0.0236$ fm.
In the hybrid model, all nuclei were divided into four groups: light ($Z≤17$), medium ($18≤Z≤31$), medium-heavy ($32≤Z≤51$), and heavy nuclei ($Z≥52$). Parameters of the hybrid network were separately defined in each group of nuclei. After combining, they created a single model for describing the radii of all nuclei, which was the basis for systematics.
Figure 1 shows how the hybrid model (polyline) describes the experimental data (black circles) in the group of light nuclei. The model reproduces jumps and characteristic fractures in the mass dependence of radii in isotopic chains. When the domain of definition is expanded by $A$ and $Z$, the model errors increase dramatically [1]. Further development of the model is associated with the attraction of additional information about the nuclear binding energy and deformation.Fig.1. The root-mean-square charge radii of light nuclei with $Z≤17$.
- N.J.Ilinykh, L.E.Kovalev. Particle and Nuclei, Letters, 2018, v.15, p.558.
- I.A.Mitropolsky, L.P.Kabina, S.S.Lisin. The certificate 2018621327 of state registration of the database, Rospatent, 2018.
Speaker: I.A. Mitropolsky (PNPI of NRC Kurchatov Institute) -
134
STRUCTURE AND PROPERTIES OF NUCLEAR ISOMERS. ON THE 100TH ANNIVERSARY OF THE DISCOVERY OF NUCLEAR ISOMERISM
In some nuclei, there are metastable states with "anomaly" long lifetimes, called nuclear isomers [1]. The report mentions the main events of the history of the discovery and research of the phenomenon of nuclear isomerism. The properties of isomeric states with a lifetime of more than 1 second (605 isomers in 548 nuclides) are considered on the base of the ENSDF 2021 file [2].
Studying the isomer properties is an excellent test of the correctness of our ideas about the structure of the nucleus. It is possible to distinguish isomerism by spin (in deformed nuclei – by the spin projection), by the equilibrium form, in particular the intruder states and fission isomers, and by the excitation energy. In the latter case, the transition energy is so small, for example, at $^{235}$U or $^{229}$Th, that the electromagnetic lifetime becomes large even in the absence of other prohibitions.
Nuclear isomers are energy accumulators, so the search for controlled deexcitation methods would open the way to a new energy source [3]. The discovery of the neutron acceleration in an "isomeric" medium, when thermal neutrons, inelastic scattering on isomers, carry away their energy, proves that such a statement of the question makes sense. The cross-section of such a process at the isomeric state of $^{180m}$Hf is $σ_{in}=52 (13)$ bn [4].
The excitation of isomers in the neutron capture allows us to study the influence of the resonant environment on their lifetime. For example, for the $^{119m2}$Sn isomer, an increase in the observed lifetime of 5% was obtained, depending on the increase in the concentration of tin nuclei and the creation of Moessbauer resonance conditions [5]. The continuation of these studies opens up new prospects for the use of this phenomenon in nuclear technologies.- O.Hahn. Berichte der Deutschen Chemischen Gesellschaft, 1921, Bd.54, S.1131.
- ENSDF 2021: https://www.nndc.bnl.gov/ensdf/.
- E.V.Tkalya. Physics-Uspekhi, 2005, v.175, p.555.
V.V.Vatulin et al. Bull. of the RAS, phys. ser., 2017, v.81, p.1296. - I.A.Kondurov et al. JETP Letters, 1980, v.31, p.254;
Phys. Lett. B, 1981, v.106, p.383. - Yu.E.Loginov et al. JETP Letters, 2008, v.87, p.7.
Speaker: Ivan Mitropolsky (PNPI of NRC Kurchatov Institute)
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Section 2. Experimental and theoretical studies of nuclear reactionsConvener: Vladislav Sandul (St Petersburg State University (RU))
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135
Characteristics of Heavy-Ion Fragmentation Reactions at Fermi Energies
Heavy-ion-induced projectile fragmentation reactions at Fermi energies are of general interest as a means to investigate the properties of nuclei far from the valley of stability and for various applications. It is thus of importance to understand in detail the production mechanism. Here we treat such reactions in a microscopic approach, which consists of three steps: initialization of ground states of the colliding nuclei, dynamical evolution until the freeze-out point where the primary fragments can be identified, and de-excitation of these primary hot fragments. For the dynamical evolution we use a Boltzmann-Vlasov-type transport code, and for the de-excitation a statistical multi-fragmentation description. Here we further introduce realistic, stable initializations of the colliding nuclei, which are important to control and determine the excitation energies of the nuclei and fragments. We apply this approach to collisions of light projectile nuclei, and calculate isotope distributions and velocity spectra of the produced isotopes. In particular, the velocity spectra are shown to contain much information on the reaction mechanism.
Speaker: Dr Tatiana Mikhailova (JINR) -
136
A Systematic Study of Excitation Functions of Various Evaporation Residues in Heavy Ion Reactions at Moderate Excitation Energy: Incomplete Fusion Vs Complete Fusion
A Systematic Study of Excitation Functions of Various Evaporation Residues in Heavy Ion Reactions at Moderate Excitation Energy: Incomplete Fusion Vs Complete Fusion
Avinash Agarwal1*, Anuj Kumar Jashwal1, I. A. Rizvi2, R. Kumar3 and A. K. Chaubey4
1 Department of Physics, Bareilly College, Bareilly, MJPR University, Bareilly – 243001 INDIA
2 Department of Physics, Aligarh Muslim University, Aligarh – 202 002, INDIA
3 Nuclear Physics Group, Inter University Accelerator Center, New Delhi-110 067, INDIA
4 Department of Physics, Addis Ababa University, P. O. Box 1176, Addis Ababa, ETHIOPIA
* Email: avibcb@gmail.comStudy of heavy ion induced reactions with special reference incomplete fusion (ICF) and complete fusion (CF) process has been a subject of paramount interest of nuclear physicists working on heavy ion (HI) nuclear reactions at low and intermediate energies [1–4]. Measurement and analysis of excitation functions of various evaporation residues populated in nuclear reactions induced by heavy ions (HIs) occurring at near and above barrier energies provides inimitably sensitive probes of the actual reaction dynamics mostly associated in heavy ion interactions. Present work is an attempt to exclusively measure and study the excitation functions (EFs) of evaporation residues populated in 12C+159Tb system at energies ≈ 4.5 – 6.5 MeV/nucleon. The stacked foil activation technique followed by offline γ – ray spectroscopy
with a high-resolution HPGe detector has been employed. The experimentally measured excitation functions are compared with the theoretical predictions obtained from statistical model code PACE- 4 [5]. For xn and/or pxn channels, the experimentally measured excitation functions are found to be in good agreement with theoretical predications. However, in case of α emitting-channels, the measured EFs had significantly more production cross-section values than PACE-4 predicated values, which may be credited to the incomplete fusion (ICF) of the projectile with the target nucleus.
The coupled channel (CC) calculations are also performed using a modified version of the code CCFULL [6] for the present system. CC calculation performed using the code CCFULL do not take into account the coupling to unbound or continuum state and hence the breakup of the incident projectile is not considered into account. The experimental data have been compared to the result of CC calculation. A good description of the experimentally measured CF cross section data can be obtained by multiplying the CC calculation, by a factor of 0.89. Thus, it can be concluded that experimentally measured CF cross sections for 12C+159Tb system have been suppressed by 11% in comparison to value predicted by CC calculations performed by using the code CCFULL.References:
1. Avinash Agarwal et. al., Phys. Rev. C 103, 034602 (2021)
2. Munish Kumar et. al., Phys. Rev. C 100, 034616(2019)
3. Sabir Ali et. al., Phys. Rev. C 100, 064607 (2019)
4. Amit Chauhan et.al., Phys. C 99, 064609 (2019)
5. A. Gavron, Phys. Rev. C 21, 230 (1980).
6. K. Hagino et. al., Comput. Phys. Commun. 123, 143 (1999)Speaker: AVINASH AGARWAL (DEPARTMENT OF PHYSICS,MJPR UNIVERSITY, BAREILLY COLLEGE, BAREILLY) -
137
Alpha decay of Polonium isotopes using different choices of assault frequency
The alpha (α) emission is one of the prominent ground state decay mechanism, which is used as investigating tool to understand the relative stability of a nuclear isotopes. In last few decades, many experimental and theoretical attempts were made to understand the cluster-core interplay of radioactive nuclei. The preformed cluster model (PCM) [1,2] have successfully explored α-particle and other ground state decay modes in recent years. In this methodology, cluster is supposed to be preformed inside the mother nucleus and the preformation probability of decaying fragment serves as an important tool to investigate the half-life and the decay constant. The relative stability of a nucleus depends on the decay constant which is the product of three factors such as assault frequency (ν0), penetration probability (P) and the preformation probability (P0). In this work, we have used the classical and quantum mechanical assault frequency in reference to [3]. Classically, it is considered that alpha particle move back and forth inside the nucleus. In the quantum mechanical approach the alpha particle is considered to be vibrating near the surface of parent nucleus, under the influence of harmonic oscillator potential. A comparative study is carried out for the alpha decay of Polonium (Po) isotopes (having mass AP=188-218) within the framework of PCM. The fragmentation potential, preformation probability and penetration probability of considered Po isotopes are investigated. The relevant role of proton (Z) and neutron (N) magic shell closures of the daughter nuclei is worked out. The PCM calculated α-decay half-lives are calculated using both assault frequency approaches and compared with the available experimental data [4].
Speakers: Nitin Sharma (Thapar Institute of Engineering & Technology, Patiala, India), Prof. Manoj Kumar Sharma (Thapar Institute of Engineering & Technology) -
138
ALPHA PARTICLES EMISSION IN FAST NEUTRONS PROCESSES ON 143ND NUCLEUS
Nuclear reactions induced by fast neutrons starting from 0.5 MeV up to 25 MeV followed by alpha particles emission were investigated. Cross sections, angular correlations and related asymmetry effects were evaluated with Talys [1] and own computer codes. Contribution to the cross section of nuclear reaction mechanisms like direct, compound and pre-equilibrium together with discrete and continuum states of residual nuclei were determined. Theoretical evaluations are compared with existing experimental data. Further, parameters of nuclear potential in the incident and emergent channels are obtained. Using cross-section and angular correlation theoretical Talys data, forward-backward effects are obtained for different incident neutron energies and target dimensions. The Simulated forward-backward asymmetry coefficient is much lower than the experimentally measured effect [2]. The difference can be explained by the presence of other emergent channels including alpha particles and not by the existece of so-called non-statistical effects suggested in [2].
The present work was realized in the frame of the fast neutrons scientific program from FLNP JINR Dubna.Speaker: Alexandru Ioan Oprea (JINR) -
3:10 PM
Coffee break
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139
Test setup for registration of coincident signals from reactions with the emission of charged particles and neutrons on the RADEX channel
The neutron beam of the RADEX channel of the INR RAS is used by us to study few-nucleon reactions caused by neutrons with an energy of $10-100$ MeV. The registration in the coincidence of neutrons and charged particles, their identification and energy determination are necessary for study such reactions. For the preliminary test measurements, the reaction $n + ^{6}\text{Li} \rightarrow \alpha + d + n$ with the registration of secondary alpha particles and neutrons was chosen.
The kinematic simulation according to the technique described in [1] showed that it’s possible to register alpha particles and neutrons on opposite sides of the beam axis at angles of $\sim 90^\circ$ and $\sim 30^\circ$ respectively.
Test measurements can be considered successful if there are peaks in the energy spectrum of alpha particles corresponding to the breakup of the ground and excited states of the $^{6}\text{Li}$ nucleus in coincidence with the neutron signal.
To test the possibility of registration in the coincidence of charged particles and neutrons a prototype of the setup was created (fig. 1). The setup prototype includes a small vacuum scattering chamber with an installed $^{6}\text{Li}_{2}\text{CO}_{3}$ target and an $\Delta E - E$ telescope of silicon. A neutron detector based on an organic scintillator makes it possible to distinguish signals from neutrons and gamma quanta by the pulse shape. To measure the neutron energy by time-of-flight the fast $\Delta E - E$ signals of the telescope are used as start impulse.
The setup was tested on the neutron beam of the RADEX channel. The obtained experimental data are currently being processed.
It’s assumed that the use of the second arm for the registration of charged particles and a thin target will make it possible to significantly expand the program of investigated few-nucleon reactions on the neutron beam of the RADEX channel. It will also be possible to reconstruct the complete kinematics of such reactions with the separation of background and investigated reactions.- S.V. Zuyev, A.A. Kasparov and E.S. Konobeevski // Bull. Russ. Acad. Sci.: Phys. 2017. V.81. №6. P.679.
Speaker: Aleksandr Kasparov (INR RAS) -
140
NEW PHOTONEUTRON REACTION CROSS SECTIONS FOR Pb ISOTOPES
The total photoneutron yield reaction cross sections (,xn) = (,1n) + 2(,2n) + 3 (,3n)+… for 208Pb were obtained in experiments carried out using bremsstrahlung, quasimonoenergetic annihilation photons (Livermore (USA) [1] and Saclay (France) [2], and tagged photons [3]. Available data were evaluated using the method of reduction – the special treatment for converting different experiments data into the form for the monochromatic photon effective spectrum [4]. The comparison of data forces one to conclude that all cross sections under discussion agree to each other with exception of Livermore one having a significantly lover value. Using the experimental-theoretical method and the objective physical criteria of data reliability partial reactions (,1n), (,2n), and (,3n) cross sections were evaluated [5] using the Saclay [2] cross section exp(,xn). It was shown that significant differences between Saclay and Livermore, as well as between evaluated and Livermore, data are the results of the loss notable amount of neutrons from the reaction (,1n). Data for total and partial reactions for 206,207Pb were obtained only at Livermore in the same experiment as for 208Pb [1]. Because similar to the situation for 208Pb the values of both exp(,xn) cross sections are noticeably smaller in comparison with the once theoretically calculated in the frame of the Combined PhotoNucleon Reaction Model (CPNRM) [6] both exp(,xn) for 206,207Pb were normalized to the theor(,xn) with the factors 1.21 (207Pb) and 1.13 (206Pb). With those normalized exp(,xn) the reliable cross sections for (,1n), (,2n), and (,3n) reactions were evaluated using experimental-theoretical method. It was obtained that new evaluated cross sections are noticeably different from the experimental once. It was shown that in analogy to the situation for 208Pb such kind differences in the cases of 206,207Pb could be explained only by the loss many neutrons from the reactions (,1n).
- R.R. Harvey et al., Phys. Rev. 136, B126 (1964).
- A. Veyssiere et al., Nucl. Phys. A 159, 561 (1970).
- L.M. Young, Ph.D. Thesis, University of Illinois, 1972.
- V.V. Varlamov et al., IAEA NDS, INDC(CCP)–393, IAEA, Vienna, Austria, 1994.
- V.V. Varlamov et al., Phys. Atom. Nucl. 76, 1403 (2013).
- B.S. Ishkhanov et al., Phys. Atom. Nucl. 71, 493 (2008).
Speaker: Prof. Vladimir Varlamov (Lomonosov Moscow State University) -
141
Non-statistical nature of fragments' spin distributions in binary nuclear fission
Since for spontaneous and low-energy induced fission, compound fissile nuclei and primary fission fragments in the vicinity of the scission point are in cold nonequilibrium states [1], when constructing the spin distributions of these fragments, it is necessary to take into account [2,3] only zero transverse bending- and wriggling-vibrations of the indicated fissile nuclei. Expressing the normalized distribution function of $W\left(\mathbf{J_1}\mathbf{,}\mathbf{J_2}\right)$ fission fragments over spins $\mathbf{J_1}$ and $\mathbf{J_2}$ in terms of the product of the squared moduli of the wave functions of zero bending- and wriggling-vibrations, one can obtain [4]:
$ W\left( {{\mathbf{J}}_{\mathbf{1}}}\mathbf{,}{{\mathbf{J}}_{\mathbf{2}}} \right)=\frac{4{{J}_{1}}{{J}_{2}}}{\pi {{C}_{b}}{{C}_{w}}}\exp \left[ -\frac{1}{2}\left( \frac{1}{{{C}_{b}}}+\frac{1}{{{C}_{w}}} \right)\left( J_{1}^{2}+J_{2}^{2} \right)+\left( \frac{1}{{{C}_{b}}}-\frac{1}{{{C}_{w}}} \right)J_{1}^{{}}J_{2}^{{}}\cos \phi \right], (1)$
where $\phi \left(0\le \phi \le 2\pi \right)$ is the angle between the two-dimensional spin vectors of fragments $\mathbf{J_1}$ and $\mathbf{J_2}$ lying in plane $XY$. By integrating in (1) over variables $J_2$ and $\phi$, one can obtain [4] the normalized distribution of spin $J_1$ of the first fission fragment and estimate the average value $\bar{J}_1$ of spin $J_1$:
$ W({{J}_{1}})=\frac{4{{J}_{1}}}{{{C}_{b}}+{{C}_{w}}}\exp \left[ -\frac{2J_{1}^{2}}{{{C}_{b}}+{{C}_{w}}} \right],\bar{J}{}_{1}=\int\limits_{0}^{\infty }{{{J}_{1}}W({{J}_{1}})}d{{J}_{1}}=\frac{1}{2}\sqrt{\frac{\pi }{2}}{{\left( {{C}_{b}}+{{C}_{w}} \right)}^{{1}/{2}\;}}.(2) $For a fissile nucleus $^{236}$U at values [4] of parameters $M_w=1.6\cdot10^6\text{MeV}\cdot\text{Fm}^2\cdot\text{s}^2$; $M_b=2.0\cdot 10^6\text{MeV}\cdot\text{Fm}^2\cdot\text{s}^2$; $K_w=295\text{MeV}\cdot\text{rad}^{–2}$; $K_b=52\text{MeV}\cdot\text{rad}^{–2}$; $\hbar\omega_w=2.3\text{MeV}$; $\hbar\omega_b=0.9\text{MeV}$; $C_w=132\hbar^2$ and $C_b=57\hbar^2$, it follows that the energies of vibrational quanta $\hbar\omega_w$ and coefficients $C_w$ for wriggling-vibrations turn out to be noticeably larger than those for bending-vibrations. This means that the main contribution to $\bar{J}_1$ (2) comes from wriggling vibrations. Then the calculated value $\bar{J}_1=8.6$ correlates well with the experimental [5] average values of the spins of fission fragments $\bar{J}_1=7–9$.
This means that the spin distribution of fission fragments is determined with a good degree of accuracy by taking into account zero wriggling and bending vibrations of a composite fissile system. This confirms the assumption [6] about the inequality of the statistical Gibbs distribution with temperature $T$ for the spin distribution of fragments, which is used in [1].
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Bohr A. and Mottelson B. Nuclear Structure (W.A. Benjamin, NY, Amsterdam, 1969).
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V.E. Bunakov, S.G. Kadmensky, D.E. Lyubashevsky // Phys. At. Nucl. V. 79. P. 304 (2016).
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S.G. Kadmensky, V.E. Bunakov, D.E. Lyubashevsky // Phys. At. Nucl. V. 80. P. 447 (2017).
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J.B. Wilhelmy, et al., Phys. Rev. C V. 5. P. 2041 (1972).
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A. Gavron, Phys. Rev. C V. 13. P. 2562 (1976).
Speaker: Dmitrii Lyubashevsky (Voronezh State University) -
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142
Analysis of neutron-induced fission cross-sections of Pb isotopes near the closed neutron shell
We analised the fission cross-section of Pb-204, Pb-206, Pb-207 and Pb-208 nuclei at neutron energies varied from 30 MeV up to 180 MeV. Experimental data were obtained from [1]. The main parameters influence the calculated fission cross-sections are the height of the fission barrier and the level density at the top of the barrier. The height of the barriers are determined by the shell corrections which are different for different near magic Pb-208 nuclei. We determine the barrier heights fitting the experimental cross-sections with TALYS code calculations. An example of experimental fission cross-section for Pb-207 nucleus is shown on Fig.1. The solid line on the figure is the result of the TALYS calculation. Difference of the obtained barriers with liquid drop model barrier heights or Sierk model heights [2] give the size of the shell correction of the fissioning nuclear at the deformation on the top of the barrier.
The auther is grateful to A.N. Smirnov for stimulating interest in the problem.- I.V. Ryzhov et al., NIM A 562, 439 (2006)
- A.J. Sierk, Phys. Rev. C 33, 2039 (1986)
Speaker: Mikhail Onegin (Petersburg Nuclear Physics Institute) -
143
Separation efficiency and separation time of mass separator MASHA measured for radon and mercury isotopes
The discovery of the Super Heavy Elements (SHE) with atomic number Z=113-118 as well as new neutron excess isotopes of the elements with Z=104-112 was one of the outstanding scientific results of the last decades. These high priority experiments were carried out on the cyclotron U400 of the FLNR (JINR, Dubna, Russia). The synthesis of the new super heavy elements stimulated works on the development of methods of their identification by means of the technique called Isotope Production On-Line (ISOL). Thereto, in the FLNR there was designed and put into commissioning the mass separator MASHA - Mass Analyzer of Super Heavy Atoms. The uniqueness of this mass spectrometer consists in ability to measure "on line" the masses of the synthesized isotopes of the super heavy elements simultaneously with detection of their alpha decays and spontaneous fission.
The main characteristics of MASHA setup is the separation efficiency and separation time. To determine these parameters two experiments by using the complete fusion reactions $^{40}$Ar+$^{144}$Sm and $^{40}$Ar+$^{166}$Er, E$_{beam}$ = 5-7 MeV/n, were carried out. The experiments were carried out at the U400M cyclotron of the FLNR, JINR (Dubna). In the first experiment, the absolute cross sections of evaporation residua (radon and mercury isotopes) were obtained. In addition the absolute cross sections for p(xn) and $\alpha$(xn) reactions were also measured. The method of moving absorber made of ultra-thin aluminum foils (0.8 $\mu$m), where the reaction products were stopped, was used. The alpha decay of synthesized isotopes was detected by using silicon detectors. Energy resolution of alpha-radioactive isotopes was ~ 100 keV. Time moving of aluminum absorbers between two extreme positions was 0.3 s. The using of beam interruption method allowed to measure half-life of synthesized nuclei. As a result, the method allowed reliable identification of reaction products. In the second experiment, the excitation functions of the same reactions were measured with upgraded mass separator MASHA including the modernization of rotating target assembly, solid hot catcher, ECR-ion source, beam diagnostics and DAQ system. To register the products of nuclear reactions, a multi-strip silicon detector was installed in the focal plane of the mass separator.
By direct comparison of these results, the separation efficiency and separation time of evaporation residua were determined.Speaker: Alena Kohoutová (Joint Institute for Nuclear Research) -
144
Spin-correlation experiment for investigating dd reactions in PNPI
After Leemann et al. [1] experimentally demonstrated that the thermonuclear reaction cross section of $^{3}He(d,p)^{4}He$ could be increased by a factor of 1.5 by using polarized reactants, theorists [2] showed that the same effect could be achieved with other reactions, in particular, in $^{2}H(d,p)^{3}H$ and $^{2}H(d,n)^{3}He$. The usage of polarized particles could lead to improvements of future thermonuclear reactors. However, there are no experiments performed with both polarized deuterons at energy below 100 keV due to its complexity and high cost. Low cross-sections and cosmic background are the biggest issues of the experiment.
PNPI Gatchina (Russia) in collaboration with Forschungszentrum Juelich (Germany) and INFN University of Ferrara (Italy) have been carring out the first low-energy spin-correlation experiment POLFUSION [3] with both reactants polarized. Two polarized beam sources have been brought to Gatchina from KVI (Groningen, Netherlands) and University of Ferrara with necessary improvements [4]. The $4 \pi$ detector system to measure the angular distributions of the fusion products has been developed by PNPI. It consists of 576 silicon PIN photodiodes arranged in a cubic structure.
POLFUSION sets the goal to measure vector and tensor analyzing powers, spin correlation coefficients, quintet state suppression factor of dd reactions with various combinations of polarization directions. The results will allow to solve the discrepancy
between different theoretical predictions.
The experimental setup is described. Results of the test-run in 2020 are presented. Details of future plans are discussed.- Ch. Leemann, H. Buergisser, P. Huber, U. Rohrer, H. Paetz gen. Schieck, F. Seiler, Ann. Phys. (N.Y.) 66, 810 (1971).
- H. Paetz gen. Schieck, The status of “Polarised Fusion”, Eur. Phys. J. A44, 321–354 (2010).
- K. Grigoryev et al., Double polarized dd-fusion experiment, J. Phys.: Conf. Ser. 295 (2011) 012168.
- A. Solovev et al., JINST 15 C08003 (2020).
Speaker: Mr Ivan Solovyev (NRC Kurchatov Institute PNPI (RU))
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135
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Section 3. Modern nuclear physics methods and technologiesConvener: Dmitrii Nesterov (St Petersburg State University (RU))
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145
New mechanic and cooling systems for the silicone detectors used in high energy physics experiments
A key role for charged particles tracking in modern high energy physics experiments, belongs to the central vertex detectors surrounding the interaction point. With these detectors, it can be possible to investigate heavy-flavour particle (registering of the particles containing c and b quarks) physics and investigate the space-time evolution of strongly interacting matter so-called quark-gluon plasma. To achieve these goals, it is important to improve the spatial resolution of primary and secondary vertices and to decrease a registration threshold for transverse momenta of charged particles. Therefore, the new pixel detectors with minimum material budget (to reduce the multiple scattering effects) and efficient mechanic and cooling systems should be used for tracking charged particles.
In the present work, the ideas, developments and studies of mechanic and cooling systems for novel vertex detectors based on silicon pixel sensors have been presented. The obtained results can be used in both high-luminosity collider experiments and for some high-technology medical applications.
The reported study was supported by RFBR, research project No. 18-02-40075.Speaker: Dmitrii Nesterov (St Petersburg State University (RU)) -
146
Complex estimation of the proportional chamber cathode surface condition after work at Large Hadron Collider experiment
In the report the complex study of the multiware proportional chamber cathodes surface that had worked under continuous radiation exposure conditions at Large Hadron Collider (LHC) experiment was performed. At the areas where the spontaneous self-supporting electron emission effect (Malter-effect – ME) was observed and where there was no effect, the cathode surface was investigated. For the first time the detector cathode surface was studied with the help of a set of methods including nuclear-scanning microscopy, atomic-scanning microscopy, Raman spectrometry and Roentgen-phase analysis. An essential difference at cathode surface structure at the regions with or without ME was detected. Possible mechanisms inducing this electron emission effect are discussed.
Speakers: Dr Gennadii Gavrilov (Petersburg Nuclear Physics Institute named by B.P.Konstantinov of NRC «Kurchatov Institute»), Prof. Marina Buzoverya (All-Russian Research Institute of Experimental Physics) -
147
Analyzing power in quasi-elastic proton-proton scattering at the beam energies of 200-650 MeV/nucleon
Analyzing power of the quasi-elastic proton-proton scattering was obtained using a polarized deuteron beam and a polyethylene target at the Nuclotron Internal Target Station. The selection of useful events was performed using time and amplitude information from scintillation counters. The asymmetry on hydrogen was obtained by the carbon background subtraction. The analyzing power values were obtained at the beam energies of 200-650 MeV/nucleon and were compared with the predictions of the partial-wave analysis. The obtained values show the possibility of the deuteron beam vector polarization determination using this method.
Speaker: Ivan Volkov (JINR) -
148
Proton polarimeter for the experiments at the Nuclotron
Terekhin A.A.1, Ladygin V.P.1, Piyadin S.M.1, Khrenov A.N.1, Isupov A.Y.1, Reznikov S.G.1, Gurchin Y.V.1, Janek M.2, Tishevsky A. V. 1, Volkov I. S.
1 Joint Institute for Nuclear Research, Dubna, Russia;
2 Physics Department, University of Zilina, Zilina, Slovakia;
E-mail: aterekhin@jinr.ruThe polarimeter upgrade program at the Nuclotron for the experiments at the internal target are presented. This polarimeter is intended for measurements of the proton and deuteron polarisation. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy are performed. The results of the first test of the new detectors are presented.
Speaker: Arkadii Terekhin (JINR) -
3:10 PM
Coffee break
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149
Towards MAPS based Inner Tracking System of NICA MPD.
The Multipurpose Detector (MPD) of the NICA complex at JINR will include an Inner Tracking System (ITS) which is a vertex detector meant to complement the Time Projection Chamber of the MPD for the precise tracking, momentum determination and vertex reconstruction for hyperons ($\Lambda$, $\Xi$, $\Omega$) and D-mesons. It will be placed inside the bore of the TPC and it will be composed of 5 layers of silicon Monolithic Active Pixel Sensors (MAPS) grouped in two barrels, with 3 layers on the inner barrel and 2 layers on the outer barrel (Fig. 1), with a spatial resolution of less that 5 $\mu$m and a material budget of less than 0.8%$X_0$. The project is a collaboration between Russian and Chinese institutions lead by the JINR and the Central China Normal University, respectively. The production and assembly of the detector will be shared by both countries, while the mechanics will be designed and manufactured completely at JINR and the readout electronics will be developed and produced in China. The project foresees the construction of the outer barrel on a first stage (2022/2023) based on the same MAPS technology used for the outer barrel of the ALICE-ITS2 1 currently under commissioning at CERN as the first MAPS-only large area ($\sim$ 10 m$^2$) detector. These are 15 mm x 30 mm x 100 $\mu$m silicon sensors (from TowerJazz 180 nm CMOS technology) with 1024 x 512 pixels. The addition of the inner barrel is programmed for a second stage (2025/2026) with the intention of building it based on 280 mm-long and 30 $\mu$m-thick bent sensors currently under R&D by the ALICE-ITS3 project at CERN [2]. Nevertheless, the use of the current ALICE-ITS2 inner barrel technology (15 mm x 30 mm x 50 $\mu$m) is considered as a backup plan. Figure 1 shows a cut of the MPD-ITS geometry along with a breakdown of one of the 42 Stave structures that compose the outer barrel. Each one of this Staves is segmented into two identical structures (Half Staves) where 2 rows of 7 MAPS are attached to a Flexible Printed Circuit to conform a structure called Hybrid Integrated Circuit (HIC) and 7 of this HICs are glued to a multilayer composite graphite plate with embedded cooling pipes (Cold Plate). According to the current MPDRoot-based simulation results [3, 4] of the MPD tracking system (ITS + TPC) for central Au + Au collisions at $\sqrt{S_{NN}}$= 9 GeV, on the initial stage with only 2 layers (outer barrel) and a beam pipe dimeter of 64 mm the signal extraction of reconstructed hyperons from the invariant mass spectrum of their decay products would be performed with an efficiency of 0.2% which is enough for assessing the identification ability of the system at debugging stage. On the other hand, only with the setup of a 5-layers ITS plus the TPC and a beam pipe diameter of 40 mm would it be possible to achieve a reliable detection efficiency of about 1% for both multi-strange and charmed particles.
References:
1. M. Mager et al., NIM A, 824 434–438 (2016).
2. "Expression of Interest for an ALICE ITS Upgrade in LS3" ALICE-PUBLIC-2018-013 (https://cds.cern.ch/record/2644611/files/ITS3%20EoI.1.pdf).
3. A. I. Zinchenko et al., Phys. Part. and Nucl. Lett., 17, 856–870 (2020).
4/ D.A. Zinchenko, et al., Phys. Part. and Nucl. Lett., 18, 134 (2021).Speaker: Cesar Ceballos Sanchez (Joint Institute for Nuclear Research (RU)) -
150
Particle identification methods in the BM@N experiment
The BM@N (Baryonic Matter at the Nuclotron) is a fixed target experiment at the NICA (Nuclotron-based Ion Collider fAcility). The first physics runs were carried out with the collection of experimental data in 2018. One of the important problems of the experiment is particles identification. This paper discusses the implemented identification algorithms based on the separation of charged particles by time of flight. The implemented methods were planned to be applied to experimental and Monte Carlo data. However, the experimental data are noisy, therefore, before applying identification methods to them, the filtering procedures described in this work were carried out. The paper also describes the implemented algorithm for calculating the efficiency of stations. It is used in order to determine how much better the Monte Carlo data than the experimental ones. After adding in the Monte Carlo data effects that make them more similar to the results obtained in the experiment, the identification method was applied to them. The results of the effectiveness of the method, obtained by testing it on modified Monte Carlo data, are presented in this work. This work is supported by Russian Foundation for Basic Research grant 18-02-40104 mega.
Speaker: Konstantin Mashitsin (St Petersburg University) -
151
Calibration and performances of the electromagnetic calorimeter at MPD/NICA.
The electromagnetic calorimeter (ECal) is an integral part of the MPD experiment and designed to measure the energy and coordinates of photons and electrons as a manifestations of the nuclear matter properties. ECAL has a segmented structure and consists of 2.400 modules, everyone has 16 cells (towers). Each tower is assembled from 210 layers, which is a set of alternating lead and scintillation plates pierced with wavelength shifting fibers to transport light to photodetectors [1]. Mass production of calorimetric modules was launched last year. At the present time, more than 300 modules of various types have been produced. The calorimeter modules are tested and calibrated in two directions: on the stand at JINR using cosmic rays and on the electron beam of S-25R «Pakhra» of the Lebedev Physics Institute [2]. This report presents the methods and results of calibration and testing of the selected ECal modules. The simulation programs for beam and cosmic tests were developed [3]. Last experimental results in comparison with simulated data are presented and discussed. This work was supported by RFBR grant no. 18-02-40079.
Keyword: Multi-Purpose Detector, electromagnetic calorimeter (ECal), «Pakhra» synchrotron, calibration, cosmic rays, nuclаer matter properties
- V. V. Kulikov et al., JINST 15, C09017 (2020) 09.
- V.I. Alekseev et al., Bull. Lebedev Phys. Inst. 47, 201 (2020).
- A. Yu. Semenov et al., JINST 15, C05077 (2020) 05.
Speaker: Mr M. A. Martemianov (NRC «Kurchatov Institute» - ITEP, Moscow 117218, Russia) -
152
Scintillation detector prototypes for Beam-beam counter at NICA SPD
The Beam Beam Counter of the Spin Physics Detector at NICA is proposed for local polarimetry and luminosity monitoring. The main option of the Beam Beam Counter is the scintillation tiles with SiPM readout. The work presents the results for studies the scintillation detector prototypes using two developed options of the front-end electronics. The estimation of time resolution using the time-walk correction procedure, as well as the coordinate scanning are discussed.
Speaker: Mr Aleksey Tishevsky (JINR) -
153
Cathode strip chambers for the outer tracker of the BM@N experiment
Baryonic Matter at Nuclotron (BM@N) is a fixed target experiment at the NICA accelerator complex (JINR) aiming at studies of nuclear matter in relativistic heavy ion collisions. The outer tracking system for the BM@N heavy ion beam program is based on Cathode Strip Chambers. The outer tracker will be installed downstream the analyzing magnet to precise parameters of tracks, obtained in central tracking system and to find corresponding hits in time-of-flight systems. The full configuration of the CSC tracking system will include four CSC of the size 1129×1065 mm$^2$ and two CSC of the size 2190×1453 mm$^2$. First Nuclotron beam test of the 1129×1065 mm$^2$ CSC was performed in beams of C, Ar and Kr ions in March 2018: the chamber was installed in front of time-of-flight detectors to check its performance as outer tracker for heavy ions. The structure of the BM@N CSC detectors and the results of the study of their characteristics are presented. The full configuration of the CSC tracking system is shortly reviewed.
Speaker: Rasuljon Kattabekov (JINR) -
154
READOUT ELECTRONICS OF THE SILICON TRACKING SYSTEM OF THE BM@N EXPERIMENT AT NICA
BM@N experiment at NICA in Dubna is currently being upgraded for the study of dense nuclear matter in heavy-ion collisions. One of the major upgrades is a new hybrid tracking system consisting of large-area Silicon Tracking System (STS) and seven GEM planes. The STS contains four tracking stations equipped with double-sided micro-strip silicon sensors of CBM-type. To collect data from 600 000 channels, a state-of-art data acquisition system (DAQ) based on the STS-XYTER ASIC and supporting the GBT data transmission protocol is being developed and tested. The standalone, initially self-triggered STS data acquisition system must be able to operate on a trigger and be integrated into the global DAQ of the BM@N experiment. Front-end electronics, electrical connections, data concentrator and architecture of data processing board are described in the report. The results of testing of a pilot version of the readout chain are presented.
Work is supported by RFBR 18-02-40047 grant.Speaker: Mikhail Shitenkov (CBM)
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physics: Centrality, BM@N/NICA physicsConvener: Valerii Kondratev (Saint-Peresburg State University)
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155
Methods for centrality determination in heavy-ion collisions with the CBM experiment
Centrality is an important concept in a study of strongly interacting matter created in a heavy-ion collision whose evolution depends on its initial geometry. Experimentally collisions can be characterized by the measured multiplicities or energy of produced particles at midrapidity or spectator fragments emitted in the forward rapidity region. Relation between collision geometry and experimentally measured multiplicities is commonly evaluated within the Monte-Carlo Glauber approach.
We will present methods for centrality determination in heavy-ion collisions with the Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR). The multiplicity of charged hadrons is provided by the CBM silicon tracking system (STS) and connected to collision geometry parameters using the Monte-Carlo Glauber model. The energy of spectator fragments is estimated with the CBM projectile spectator detector (PSD). We will discuss possibilities to determine centrality using the PSD and Monte-Carlo Glauber model.
Speaker: Ilya Segal (National Research Nuclear University MEPhI (RU)) -
156
Spectator matter in collisions of relativistic deformed nuclei
Density distributions of many nuclei in their ground states are not spherically symmetric and are described by modified Woods–Saxon distributions using spherical harmonics [1]. Collisions of deformed $^{129}$Xe, $^{197}$Au and $^{238}$U nuclei were studied, in particular, in the ALICE experiment at the LHC [2] and in the STAR experiment at RHIC [3]. I was shown [4], that collision events with different initial orientations of deformed nuclei lead to different azimuthal distributions of multiplicities and transverse momentа of produced particles. It is also expected that by the comparison of experimental results with theoretical predictions the adequacy of the shape parametrization can be evaluated [5]. As shown [6,7], the detection of non-interacting spectator neutrons in forward Zero Degree Calorimeters helps to distinguish central $^{238}$U–$^{238}$U collisions with different initial orientations.
In the present work we use our Abrasion–Ablation Monte Carlo for Colliders (AAMCC) model [8,9] to calculate various characteristics of spectator matter in $^{238}$U–$^{238}$U collisions at RHIC. The modeling of each collision event consists of several stages. Firstly, the size and shape of spectator prefragments from both colliding nuclei are defined using Glauber Monte Carlo model. Secondly, the excitation energy of spectator prefragments is calculated. Thirdly, the minimum spanning tree (MST) clustering algorithm is applied to both prefragments to define secondary clusters. Finally, cluster decays are simulated with SMM, Fermi Break-up and evaporation models from Geant4 toolkit. In addition to spectator neutrons considered in Ref.[6,7], we also model the production of spectator protons and nuclear fragments.
We show that the yields of spectator nucleons and their forward-backward asymmetry strongly depend on the relative initial orientation of colliding $^{238}$U nuclei. As found, the widest and the narrowest distributions of the nucleon asymmetry are observed in side-side and tip-body collisions, respectively. On the one hand, body-tip collisions result in the largest (body side) and smallest (tip side) numbers of spectator nucleons. On the other hand, tip-tip and body-body collisions result in similar distributions of both observables. We also study the dependence of the multiplicity of spectator nucleons on the quadrupole deformation parameter β$_2$ of $^{238}$U. As found, larger β$_2$ leads to a higher multiplicity of spectator nucleons in tip-body $^{238}$U–$^{238}$U collisions. This makes it possible to use experiments on nucleus-nucleus collisions at relativistic energies to explore nuclear deformation.
The work has been carried out with the financial support of the Russian Fund for Basic Research within the project 18-02-40035-mega.
1. Q.Y. Shou et al., Phys. Lett. B 749, 215 (2015).
2. S. Acharya et al., Phys. Lett. B 784, 82 (2018).
3. L. Adamczyk et al., Phys. Rev. Lett. 115, 222301 (2015).
4. S. Kundu et al., Eur. Phys. J. A 55, 157 (2019).
5. G. Giacalone, Phys. Rev. C 102, 024901 (2020).
6. A. Goldschmidt et al., Phys. Rev. C 92, 044903 (2015).
7. V. Bairathi et al., Phys. Rev. C 91, 054903 (2015).
8. A.O. Svetlichnyi, I.A. Pshenichnov, Bull. Russ. Acad. Sci. Phys. 84, 911 (2020).
9. I.A. Pshenichnov, U.A. Dmitrieva, A.O. Svetlichnyi, Bull. Russ. Acad. Sci. Phys. 84, 1007 (2020).Speaker: Nikita Kozyrev (MIPT, INR RAS) -
2:20 PM
Contribution cancelled
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157
Cluster formation in spectator matter in collisions of relativistic nuclei
Nucleons which escape interactions with nucleons of the collision partner in collisions of relativistic nuclei move forward and form spectator matter. Reliable models describing the properties of spectator matter are of particular interest for modeling the response of forward calorimeters in experiments at NICA [1,2] and at the LHC [3]. In ultracentral collisions of nuclei a fireball with a large volume is formed, and residual spectator matter has a characteristic shape of a narrow crescent. In contrast to more peripheral collisions, the loss of cohesion between very few spectator nucleons can be expected and the spectator system does not reach thermal equilibrium. It can also happen in collisions of light nuclei like $^{16}$O. However, traditional abrasion-ablation models consider spectator matter only as a single excited nuclear system in full equilibrium with its subsequent decays.
In order to improve the description of spectator matter we have developed an advanced algorithm of the prefragment clusterization based on the construction of a minimum spanning tree (MST). The algorithm is implemented into the AAMCC model [4,5] to calculate the yields of spectator fragments taking into account all secondary decays. The developed MST clustering is based on the Kruskal algorithm [5] and takes into account the expansion of excited spectator matter by considering the correlation [7,8] between the matter density and its excitation energy.
With AAMCC model supplemented by the MST clustering we study the properties of spectators in ultracentral $^{208}$Pb—$^{208}$Pb collisions. In the absence of the MST clustering the number of free spectator nucleons is overestimated, while the agreement with data is restored with MST. Our approach allows us to describe better the data on fragmentation of $^{16}$O in nuclear emulsions [8,9]. However, due to neglecting alpha-clustering in initial $^{16}$O nuclei in the present version of the model the fractions of events with two and three alpha-particles are underestimated. AAMCC-MST model can be used to predict the production of spectator fragments in $^{16}$O—$^{16}$O collisions at the LHC in future runs [10].
The work has been carried out with financial support of the Russian Fund for Basic Research within the project 18-02-40035-mega.- M. B. Golubeva et al., Phys. Atomic Nucl. 76.1, 1-15 (2013).
- V. Golovatyuk et al., Nuclear Physics A. 982, 963-966 (2019).
- B. Abelev et al., Phys. Rev. C. 88, 044909 (2013).
- A.O. Svetlichnyi, I.A. Pshenichnov, Bull. Russ. Acad. Sci. Phys. 84, 911 (2020).
- I.A. Pshenichnov, U.A. Dmitrieva, A.O. Svetlichnyi, Bull. Russ. Acad. Sci. Phys. 84, 1007 (2020).
- T.H. Cormen et al., Introduction to algorithms. MIT press (2009).
- J.N. De et al., Phys. Lett. B. 638, 160 (2006).
- V.E. Viola et al., Phys. Rev. Lett. 93, 1 (2004).
- M.S. El-Nagdy et al., J. Phys. Commun. 2, 035010 (2018).
- Zhang Dong-Hai, Chin. Phys. Soc. 11(12), 1254-05 (2002).
- J. Brewer, A. Mazeliauskas, W. van der Schee, https://arxiv.org/abs/2103.01939
Speaker: Mr Roman Nepeivoda (MIPT, INR RAS) -
3:10 PM
Coffee break
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158
The identification capability of the Inner Tracking System for the detection of D-mesons at the NICA/MPD
The yields of charmed particles are the important observables sensitive to critical phenomena in QCD-matter at high baryon density. Highly efficient registration of such short-lived products of nuclear interactions using the Inner Tracking System (ITS) of Multi-Purpose Detector (MPD) based on Monolithic Active Pixel Sensors will play a key role in the charm production analysis.
The identification capability of the ITS has been studied during the Monte Carlo simulation, when reconstructing the decays of D$^{0}$, D$^{+}$ and D$^{+}_{s}$, produced in central Au+Au collisions at NICA energies. Results of D-meson reconstruction using Kalman Filter and Vector Finder tracking methods are compared.
The reported study was supported by RFBR research project No. 18-02-40119 and No. 18-02-40075Speaker: Dr Nicolai Maltsev (Saint-Peresburg State University) -
159
Probing the Gluon Helicity Distribution at SPD
Since the results the from European Muon Collaboration (EMC)
indicated that the combined quarks and anti-quarks account for only
about one-quarter of the proton spin, theories and experiments have
been trying to understand and measure the contributions from other
sources. Gluons have been of particular interest in the last couple of
decades. Spin asymmetry measurements from proton-proton collisions
sensitive to gluons are the prime channels to access this information.
After years of suggested models predicting a variety of gluon spin
contributions, RHIC results helped constrain the gluon helicity PDF
in the last decade. The proposed Spin Physics Detector (SPD) at
the NICA facility in JINR, Dubna will be an excellent laboratory to
probe various gluon spin distributions inside protons and deuterons.
In particular, double helicity asymmetry measurements at SPD will be
sensitive to the gluon helicity distributions and will make signi?cant
contributions to constrain the uncertainties in the large momentum
fraction (Bjorken $x$) region ($0.3 \leq x \leq 0.5$).Speaker: Amaresh Datta (JINR) -
160
Feasibility studies of tau-lepton anomalous magnetic moment measurements with ultra-peripheral collisions at the LHC
Ultra-peripheral heavy-ion collisions provide a unique opportunity to study two-photon induced processes. The production of tau lepton pairs in the process $\mathrm{Pb}+\mathrm{Pb} \rightarrow \mathrm{Pb}+\mathrm{Pb} + \tau^{+}\tau^{-}$ at the LHC is particularly interesting since its cross section is sensitive to poorly known electromagnetic moments of the $\tau$-lepton. Possible deviations of the anomalous magnetic moment $a_{\tau}= (g-2)/2$ of the $\tau$-lepton from the Standard Model predictions may indicate the presence of effects beyond the Standard Model, such as contributions of supersymmetric particles or composite nature of the $\tau$-lepton. In this contribution, the prospects of exclusive ditau cross section measurements in ultra-peripheral Pb-Pb collisions at the LHC will be discussed and projections for possible $a_{\tau}$ limits will be presented.
This work was supported by the Russian Foundation for Basic Research (RFBR, 21-52-14006) and the Austrian Science Fund (FWF, I 5277-N).
Speaker: Nazar Burmasov (NRC Kurchatov Institute PNPI (RU)) -
161
A Monte Carlo simulation of the BM@N detector performance for strangeness production studies in heavy-ion interactions
In a few months, the accelerator complex of the Booster and Nuclotron at JINR (Dubna) will be ready to accelerate heavy ions. At the same time, the Baryonic Matter at Nuclotron (BM@N) experimental setup is completing its configuration to investigate relativistic heavy-ion beam interactions with fixed targets.
One of the most important experimental tasks of the BM@N physics program is determination of the equation of state of the high-density baryonic matter. This task can accomplished via measurements of the (multi)strange hyperon excitation function, i.e. hyperon yields at different energies.
In the talk, the results of the Monte Carlo simulation of the BM@N detector performance for studying strangeness production in heavy-ion interactions will be presented.
Speaker: Alexandre Zinchenko (Joint Institute for Nuclear Research (RU)) -
162
Performance evaluation of the Stage-I Inner Tracking System for hyperon reconstruction at MPD/NICA
The upgrade program of the Multi-Purpose Detector (MPD) experiment at the Nuclotron-Based Ion Collider Facility (NICA) complex considers assembly and installation of an Inner Tracking System (ITS) made of Monolitic Active Pixel Sensors (MAPSs) between the beam pipe and the Time Projection Chamber (TPC). It is expected that the new detector will enhance the experimental potential for reconstruction of short-lived particles — in particular, open-charm hadrons.
The new detector is planned to be built in two stages. At the first stage, two outermost layers will be installed. In the talk, results of a Monte Carlo study of the performance of this configuration for reconstruction of (multi)strange hyperons will be presented.
Speaker: Mrs Dilyana Suvarieva (JINR) -
163
Prospects of photon conversion measurements in the future MPD experiment at NICA
The future MPD experiment at the NICA collider is aimed to study hot and dense matter created in heavy ion collisions at center-of-mass energies from 4 to 11 GeV. Measurements of photon spectra via reconstruction of electron-positron pairs from photon conversions provide a unique opportunity to probe the temperature of the produced medium and study $\pi^0$ and eta meson yields down to low transverse momenta. In this contribution, feasibility of photon conversion measurements with the MPD experiment will be discussed. A proposal to increase the photon conversion probability with a dedicated retractable converter will be presented and the prospects to probe the material budget of the experiment with converted photons will be evaluated.
This work was funded by RFBR according to the research project No.18-02-40045.
Speaker: Evgeny Kryshen (NRC Kurchatov Institute PNPI (RU))
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155
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physics: QCD; theoryConvener: Daria Prokhorova (St Petersburg State University (RU))
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164
A LIGHT-FRONT AdS/QCD QUARK-DIQUARK NUCLEON MODEL IN PROTON-PROTON AND HEAVY-ION COLLISIONS
This work discusses a phenomenological quark-diquark nucleon model based on light-front soft-wall AdS/QCD holography able to be used in particle collision simulations.
The light-front holography has predicted two particle bound state wave function inside nucleons which can not be derived simply from a picture of valence quarks, namely diquarks [1]. In this framework, from the construction of phenomenological diquark Parton Distribution Functions based on light-front QCD and soft-wall AdS/QCD [2, 3] matched to data from NNPDF2.3 QCD+QED NNLO [4, 5]; as well as, due to consequences of the color gauge $SU(3)_c$ in QCD, we have armed a nucleon model and implemented it into the PYTHIA simulation package.
The quark-diquark nucleon model contains both scalar (isoscalar-scalar diquark singlet) state and axial-vector (isoscalar-vector diquark and isovector-vector diquark) state as participating in hard-scattering process alongside quarks and gluons in particle collisions.Thanks to the hadronization machinery already existing in PYTHIA, we were able to to compare the model in the proton-to-pion ratio in proton-proton collisions at transverse momentum region $0\leq p_T \leq 20$ GeV at $\sqrt{s} = 13$ TeV with default PYTHIA processes and experimental data from ALICE experiment [6]. The quark-diquark model shows an enhancement of baryon production in the region $2\leq p_T \leq 4$ GeV, being in better agreement with experimental data than default PYTHIA models, which only consider quarks and gluons in hard processes.
On the side of heavy-ions, we compared the quark-diquark nucleon model to data from PHENIX experiment in HeAu collisions at $\sqrt{s} = 200$ GeV [7], obtaining a better agreement in the $p/\pi^+$ ratio than the default models in PYTHIA in the region $0\leq p_T \leq 3$ GeV.
In general terms, as expected from a quark-diquark nucleon model with interacting valence diquarks in hard-processes, the studied systems of collisions showed a subtle increase of production of proton over pions not observed in models without diquark hard-processes. It is proposed to generalize and use the model in phenomena where diquark degrees of freedom may play a role.References:
1. Stanley J. Brodsky, Guy F. de Teramond, Phys. Rev. Lett. 96, 201601 (2006)
2. T. Gutsche, V. E. Lyubovitskij, I. Schmidt and A. Vega, Phys. Rev. D 89 5, 054033 (2014), Phys. Rev. D 92 1, 019902 (2015) (erratum)
3. Tanmay Maji, Dipankar Chakrabati, Phys. Rev. D 94 9, 094020 (2016)
4. Richard D. Ball et al., Nucl. Phys. B 877, 290-320 (2013)
5. B. Rodriguez-Aguilar, Ya. A. Berdnikov, e-Print: 2105.05884 [hep-ph]
6. Shreyasi Acharya et al., Eur. Phys. J.C 81 3, 256 (2021)
7. D. Larionova, et al. Nucleus-2021Speaker: Benjamin Rodriguez-Aguilar (Peter the Great St.Petersburg Polytechnic University (SPbPU)) -
165
Effective models of hadrons in Quantum Field Theory on the Light Front
A possibility to obtain the spectrum of mesons (as quark-antiquark states) in effective model of Quantum Chromodynamics on the Light Front (LF) is considered. We use the effective Hamiltonian on the LF having the quark fields interracting with the zero modes of gluon fields. This effective Hamiltonian includes these terms in such a way that one can get quark-antiquark bound states. We chose these terms using arguments connected with the investigation of the limit transition to canonical formulation on the LF from the usual one, and also some semiphenomenological assumptions.
Speaker: Igor Lebedev (Saint Petersburg State University) -
166
Theory of holographic models for linear Regge trajectories and its applications
In our work we systematized various holographic models and relations between them. We started by constructing the most general theory that has a quadratic in fields, holographic 5D action violating the Poincaré invariance along the fifth coordinate, but which still produces linear Regge mass spectrum. This setup shows that a solvable Soft-Wall (SW) model with linear spectrum can have two $z$-dependent terms in the five-dimensional mass. However, as we demonstrated both these contributions can be reformulated as modifications of the AdS background.
After briefly reviewing our holographic framework outlined above, we discuss various phenomenological applications and properties of holographic models. In particular, we consider the vector two-point correlation function and pion form factor. In both cases we highlight the differences between the results produced by various SW models. In the case of pion form factor we compare our results with experimental data and show that the SW$^-$ model is remarkably successful in describing both mass spectra and pion form factor data with the universal value of the intercept, while the SW$^+$ model doesn't have this property. This is especially interesting considering that the SW$^-$ model reproduces Vector Meson Dominance concept.
Based on: arXiv:2106.01846
Speaker: Timofey Solomko (Saint-Petersburg State University) -
167
Large rapidity gap events in proton-nucleus collisions at LHC energies
Role of photon-exchange in proton-nucleus collisions with forward large rapidity gaps at LHC energies is discussed.
Relative contributions via gamma- and pomeron- exchanges for forward large rapidity gap events in proton-lead collisions are estimated.
The obtained results compared with recent preliminary CMS data at LHC.Speaker: Sergey Nasybulin (NRC Kurchatov Institute PNPI (RU)) -
3:10 PM
Coffee break
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168
Dynamic Strong Magnetic Field for Quark Gluon Plasma Equation of State
We study the equation of state of quark gluon plasma (QGP) with dynamic strong and intense magnetic field. This magnetic field is expected to be generate due to the collisions of massive nuclei at relativistic heavy ion collider and large hadron collider. To get a deeper understanding of QGP physical picture, we use a quasi-particle model with various initial condition. The calculation results with quasi-particle model are found to be significant not only in the presence of static magnetic field but also provide significant contribution for dynamic magnetic field. We compare results with and without dynamic magnetic field. The results of QGP equation of state with dynamic magnetic field give deeper insights in QGP. Therefore, the current investigation of the QGP equation of state give unique insights into the development of heavy ion collisions, early universe and various other properties of quark matter under extreme conditions. The model work is thus useful for theoreticians and experimentalists to understand QGP better.
Speaker: Dr Yogesh Kumar (Deshbandhu College, University of Delhi, india) -
169
Theoretical limitations of amplitudes and their decisive influence on the parameters of resonances
Recent years have shown how important a role in resonance spectroscopy is played by theoretical limits imposed on amplitudes. They are unitarity and crossing symmetry. Generally, it is about the analysis of the analytical structure of complex amplitudes, which are so important that, for example, they eliminate long-existing ambiguities in experimental data and dramatically change the resonance parameters. These changes strongly affect the interpretation of the resonance structure, which is crucial in searching for e.g. exotic states, so important in testing the Standard Model. These searches are the main or one of the main lines of research carried out by, for example, the GlueX, Compass and Nica projects. There is no doubt now that the decisive conclusions about these important and sometimes key topics come from theoretical analysis - much more accurate and demanding than even the data from a well-conducted and analyzed experiment. This indicates a new and often accepted, even by definition, conservative collective Particle Data Group, method of analyzing experimentally determined data and amplitudes and drawing very often revolutionary but certain conclusions so very important today for the evaluation of effects beyond the Standard Model. The presentation will show the greatest achievements of the above-mentioned methods for mesons to about 2 GeV and prospects for their further development. As an example, the results of $f_0(500)$, $\rho(1450)$ and $K^*(800)$ resonance analyzes [1,2,3] will be presented. The presentation will also encourage all physicists - experimentalists and theorists to use the presented methods and to abandon the long-known e.g. isobar models violating unitarity. Modern physics (especially after the discovery of Higgs) and its requirements, force us to apply the above-mentioned methods and undoubtedly represent the future of physics.
[1] "The Pion-pion scattering amplitude. IV: Improved analysis with once subtracted Roy-like equations up to 1100 MeV", R. Garcia-Martin, R. Kaminski, J.R. Pelaez, J. Ruiz de Elvira, F.J. Yndurain, Phys. Rev. D 83 (2011) 074004.
[2] "Strong evidence of the $\rho(1250)$ from a unitary multichannel reanalysis of elastic scattering data with crossing-symmetry constraints", N. Hammoud, R. Kaminski, V. Nazari, G. Rupp, Phys. Rev. D 102 (2020) 5, 054029.
[3] "Determination of the lightest strange resonance $K_0^*(700)$ or $\kappa$, from a dispersive data analysis", J.R. Peláez, A. Rodas, Phys. Rev. Lett. 124 (2020) 17, 172001.
Speaker: Dr Kaminski Robert (Institute of Nuclear Physics PAS) -
170
On the Possibilities of Using the Basic Principles of Quantum Field Theory for Modeling the Interaction of Neutrinos with a Strongly Inhomogeneous Medium
Recently, much attention has been paid to the effects of interaction of quantised fields with macro-objects. This area of research is important for the development of both theoretical and experimental physics, and there is every reason to believe that their results will find many scientific and technical applications. Here, to construct the models necessary for theoretical research, the Symanzik approach can be used, which was initially proposed for the description of quantum field systems with inhomogeneous space-time [1]. It was developed to describe the effects of the interaction of fields of quantum electrodynamics (QED) with two-dimensional materials. The requirements of locality, renormalisability and gauge invariance impose essential restrictions on the admissible form of the modified Lagrangian. To describe in the framework of a unified model all the effects of interaction of a homogeneous and isotropic material plane with QED fields, in the most general case, no more than nine additional dimensionless constants are sufficient [2-9].
It is proposed to apply the Symanzik approach to modeling the processes of neutrino propagation in a strongly inhomogeneous medium, taking into account the possibility of calculating the characteristics of the oscillation regime [10-12]. Scattering of neutrinos on a homogeneous isotropic plane is considered as a simple example. The analysis of the influence of their collisions with the plane on the oscillation processes is carried out.
References
- K. Symanzik, Nucl. Phys. B 190, 1 (1981).
- V. N. Markov and Yu. M. Pis’mak, J. Phys. A: Math. Gen. 39, 6525-6532 (2006);
arXiv:hep-th/0505218v3 (2005). - V. N. Marachevsky and Yu. M. Pis’mak, Phys. Rev. D: Part. Fields 81, 065005
(2010). - D. Yu. Pis’mak and Yu. M. Pis’mak, Theor. Math. Phys., 166, 1423 (2011), 175,
816 (2013), Phys. Part. Nucl. 44, 450 (2013),. - D. Yu. Pis’mak, Yu. M. Pis’mak, and F. J. Wegner, Phys. Rev. E 92, 013204
(2015). - D. Yu. Pismak and Yu. M. Pismak, Theor. Math. Phys. 184, 1329 (2015).
- Yu. M. Pismak and D. Yu. Shukhobodskaia, EPJ Web of Conf. 125, 05022 (2016),
126, 05012 (2016), 158, 07005 (2017) - Yu. M. Pismak, Phys. Part. Nucl. Lett. 15, 380 (2018).
- Yu. M. Pismak and O.Yu. Shakhova, Physics of Particles and Nuclei, 51, 4, 578
(2020). - В. Pontecorvo, Sov. Phys. JETP 6, 429 (1957) , 7 172 (1958)
- V. GгiЬоv, В. Роntесогvо, Phys. Lett. B28, 493 (1969).
- S.M. Bilenky, В. Pontecorvo Phys. Rep. 41, 225 (1978)
Speaker: Yury Pismak -
171
Multidimensional spinors and Dirac equation in the theory of superalgebraic spinors
The theory of superalgebraic spinors [1] - [6] is an extension of the theory of algebraic spinors [7]. It is a modern version of algebraic quantum field theory. The main difference of this theory from other versions of quantum field theory is that the field operators in it are the superposition of Grassmann densities in momentum space and their derivatives. In this case, gamma operators (algebraic analogs of Dirac gamma matrices) are constructed from the Grassmann densities and their derivatives. In this approach, we have proved that in the case of a four-dimensional spacetime, in addition to the five gamma operators corresponding to the Dirac gamma matrices, there are two more gamma operators (Clifford vectors). The generator of rotation in the plane of these vectors is the operator of the electric charge, and the electromagnetic field is the connection in the spinor bundle [4]. We have constructed explicitly the spinor vacuum state vector and inversion operators P, T and C [6] - [7]. We have proved that the vacuum is symmetrical with respect to the P, CT and CPT inversions. But the operators T and C transform the vacuum into an alternative one and therefore cannot be operators of the exact symmetry of the spinors [6] - [7].
This paper discusses the extension of the theory to more than four dimensions. Such a generalization is nontrivial, since in this case the classification of representations of the Lorentz group is fundamentally different from the four-dimensional case, and the spinor cannot be considered the representation (1/2, 0), and the antispinor, the representation (0, 1/2). Moreover, for an odd number of dimensions, the automorphisms of Clifford algebras are not internal. Therefore, the theory of spinor bundles is considered only for even-dimensional spaces. The use of the superalgebraic spinor formalism allows us to solve these problems.- M. Pavšič, Advances in Applied Clifford Algebras, 22, 449 (2012).
- V. V. Monakhov, J. of Physics: Conference Series 1051, 012023 (2018).
- V. V. Monakhov, Theor. and Math. Physics 200, 1026 (2019).
- V. Monakhov, Universe 5, 162 (2019).
- V. Monakhov, A. Kozhedub. Geom. Integrability & Quantization, 22, 165 (2021).
- V. Monakhov, Universe 7, 124 (2021).
- P.Lounesto, Clifford algebras and spinors, Cambridge University Press (2001).
Speaker: Prof. Vadim Monakhov (Saint Petersburg State University) -
5:10 PM
End of session
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164
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Poster session (Experimental and theoretical studies of nuclear reactions)Convener: N.A. Prokofiev (Saint Petersburg State University, Russia)
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172
INVESTIGATION OF CONTINUOS SPECTRA OF LIGHT CHARGED PARTICLES EMITTED IN PROTON INDUCED REACTION ON 103Rh NUCLEUS AT 22 MeV ENERGY
The development of the new generation of nuclear energy systems with a high level of safety (Accelerator Driven System), consisting of a proton accelerator, the neutron production target and sub critical reactor are deployed in many countries. In creating such devices for correct modeling of the neutron flux the data on the spectral composition and angular distributions of secondary protons and light charged particles produced by primary proton beam are required.
Continuous energy spectra of protons, deuterons and alphas emitted from reactions initiated by proton of 22 MeV on rhodium nucleus were measured on isochronous cyclotron U-150M of Institute of Nuclear Physics (Kazakhstan). For registration two telescopes of detectors were used. One of them consisted of silicon detector of 100 micron thickness and CsI(Tl) detector of 2.5 cm thickness (for protons and deuterons), and another consisted of 50 micron and 2 mm silicon detectors (for alphas). The self-supporting foil of Rh with thickness of 3 mkm was used in these experiments.
The energy calibration of a spectrometer was carried out on kinematics of levels of residual nuclei in the reaction 12C(p,xp) and protons of recoil. The whole systematic error was less than 10 % and the statistical uncertainty was less than 8 %.
The analysis of the experimental results has been conducted in the Griffin exciton model [1] of the preequilibrium decay of nuclei. The code Talys, which describes the emission of particles with mass numbers from 1 to 4, has been used in our theoretical calculations. A satisfying agreement between experimental and calculated values in the energy region corresponded to the pre-equilibrium mechanism has been achieved.- Griffin J. J. // Phys. Rev. Lett. 1966. №9. P.478.
Speaker: Timur Zholdybayev (Institute of Nuclear Physics) -
173
Study of the reaction based on the scattering of deuterons by a $^{9}$Be nucleus at an energy of 23 MeV
The experiment $^{9}$Be(d,d')$^{9}$Be at E(d) = 23 MeV was carried out at the HI-13 tandem accelerator, China Institute of Atomic Energy (CIAE), Beijing. Two different method of detection were used: Q3D spectrometer at forward angles and strip detectors (ΔE-E) at medium and large angles. Differential cross sections were obtained for the following excited states: g.s, 2.43, 2.78, 3.05, 3.82, 4.7, 5.59, 6.38, 6.76 and 7.94 MeV. The theoretical analysis of the obtained experimental data was carried out using the DWBA and MDM methods. The conclusion was made about the formation of bands in the $^{9}$Be.
Speaker: Viktar Starastsin (National Research Center «Kurchatov Institute») -
174
Spectroscopic factor for $^{25}$Mg→$^{24}$Mg+n through the “experimental” ANC from analysis of the peripheral transfer reactions.
A possibility of determining the spectroscopic factor (SF) for the $^{25}$Mg→$^{24}$Mg+n configuration is demonstrated by a method that significantly reduces its dependence on the model geometric parameters of the bound-state potential. In this method, to exclude the strong dependence of results on the single-particle potential parameters the additional information about the asymptotic normalization coefficient (ANC), C$^2_{exp}$ for $^{25}$Mg→$^{24}$Mg+n [1] is introduced into the DWBA analysis. ANC value is extracted from the analysis within the framework of the MDWBA method (see [2] and references therein) of the reaction $^{24}$Mg(d,n)$^{25}$Mg at E$_d$ =13.6 [3] and 14.5 MeV [1].
Studying the behavior of the test functions R(b) which is a criterion of reaction peripherality [2] in the region of the main maximum of the angular distributions at both energies indicates a strong non-peripherality of the neutron transfer process in this reaction. Here b is the one-particle normalization coefficient, that determines the amplitude of the tail of the one-particle wave function of the neutron in the nucleus $^{25}$Mg. So, owning to the MDWBA conception, one can’t extract the correct value of ANC for the configuration {$^{25}$Mg=$^{24}$Mg+n} from the MDWBA analysis. But, one can obtain the SF Z24Mg+n value if the geometry parameters of the neutron bound state potential are known (or known the single particle ANC b).
With that, owing to the established value of the ANC of this configuration from the analysis of the peripheral reaction $^{25}$Mg(d,t)$^{24}$Mg, it is possible to establish the value of the spectroscopic factor from the DWBA analysis with the additional restriction on b value. As shown in [2], the square of ANC is uniquely related to the SF Z by the relation C2 = Zb2, and the SF value for the bound state $^{25}$Mg→$^{24}$Mg+n can be obtained which is equal to . In this case, the uncertainty of its value, associated with the ambiguity of the choice of the geometrical parameters of the nuclear potential of the bound state $^{24}$Mg + n, turns out to be significantly minimized.- S.V. Artemov, et al., Doklady Akademii Nauk Uzbekistan #3, 38 (2018).
- A. M. Mukhamedzhanov, et al., Phys. Rev. C63, 024612 (2001).
- Tokarevskiy V.V., Sherbin V.N. Yadernaya fizika 22 #5, 917 (1975).
Speaker: Olimjon Tojiboev (Institute of nuclear physics) -
175
EXCITATION OF ISOMERIC STATES IN (γ, n), (n, 2n) AND (n, γ) REACTIONS ON 120,122,128,130Te NUCLEI
The isomeric ratios in reactions of the (γ, n), (n, 2n) AND (n, γ) types on 120,122,128,130Te nuclei in the energy range of 10-35 MeV have been studied by the method of induced activity. Samples of natural Sm have been irradiated in the bremsstrahlung beam of the betatron SB-50 of National University of Uzbekistan in the energy range of 1035 MeV with energy step of 1 MeV
Speaker: Prof. Satimbay Palvanov (The isomeric ratios in reactions of the (γ, n), (n, 2n) AND (n, γ) types on 120,122,128,130Te nuclei in the energy range of 10-35 MeV have been studied by the method of induced activity. Samples of natural Sm have been irradiated in the bremsstrahlung beam of the betatron SB-50 of National University of Uzbekistan in the energy range of 1035 MeV with energy step of 1 MeV) -
176
STUDY EXCITATION OF ISOMERIC STATES IN (γ,n) AND (n,2n) REACTIONS ON 82Se, 81Br AND 90Zr
This work presents work results of investigation of the isomeric yield ratios Ym/Yg of the 82Se(γ,n)81m,gSe, 82Se(n,2n)81m,gSe, 81Br(,n)80m,gBr, 81Br(n,2n)80m,gBr, 90Zr(γ,n)89m,gZr and 90Zr(n,2n)89m,gZr reactions. The isomeric yield ratios were measured by the induced radioactivity method. Samples of natural Se, Br and Zr have been irradiated in the bremsstrahlung beam of the betatron SB-50 in the energy range of 1035 MeV with energy step of 1 MeV. For 14 MeV neutron irradiation we used the NG-150 neutron generator.
Speaker: Dr Feruza Egamova (National University of Uzbekistan) -
177
EXPERIMENT FOR DETERMINING np-SCATTERING LENGTH IN THE n + d → (np) + n REACTION
In the INR RAS experimental studies of nucleon-nucleon and three-nucleon interactions and effects of charge symmetry breaking are carried out [1, 2]. A test experiment to determine the np-scattering singlet length (a$_{np}$) on the neutron beam of the RADEX channel of the INR RAS was carried out. The experiment purpose is to determine anp in the reaction n + d → (np) + n and search for the influence of three-nucleon forces (3NF). The influence of 3NF can be manifested in the difference between the a$_{np}$ value obtained in the reaction with three particles in the final state and the value obtained in the forward np-scattering.
The experiment was carried out at low neutron energies of 10$\pm$2 MeV using a C$_{6}$D$_{6}$ scintillator as an active deuterated target. The experiment consists in the registration of a recoil neutron and a neutron from the breakup of the np-system as well as the fact of registration of a breakup proton in a deuterated target.
The energy of the neutron beam, the energy and emission angle of the proton are recovered from the kinematics of the reaction n + d → n + p + n. The relative energy of the np-system is calculated for each event and then the dependence of the reaction yield on the relative energy is plotted. The experimental dependence is compared with the simulation results which depend on the np-scattering length.
The test experiment showed that it’s possible to determine the value of a$_{np}$ and to compare this value with the value obtained in the forward np-scattering at sufficient statistics.- Konobeevski E., Kasparov A., Mordovskoy M., Zuyev S., Lebedev V., Spassky A. Few-Body Syst. 2017. V.58. Art. № 107.
- E.S. Konobeevski, A.A. Afonin, S.V.Zuyev, A.A. Kasparov, V.V. Mitcuk, M. V. Mordovskoy and S.I. Potashev. Phys. At. Nucl. 2020. V.83. №4. P.523.
Speaker: Michael Mordovskoy (INR RAS) -
178
Analysis of production of forward-angle fragments in the 22Ne +Be/Ta(40 MeV/nucleon)nuclear reactions.
The velocity, charge, and isotopic distributions of the products of nuclear reactions by 22Ne +Be/Ta (40 MeV/nucleon) were obtained at COMBAS fragment separator at the U400M Research Facility in JINR. The results of velocity spectra analytical parametrization and isotopic ratios are presented. Velocity distributions are parametrized as consisting of three terms: direct Gaussian-like component representing direct component, second Gaussian-like component at smaller energies having the dissipative nature and exponential component corresponding to velocity attenuation at smaller velocities. The results are compared with model predictions. The discussion of the different mechanisms involved in these types of the reactions is given.
Speaker: Erdemchimeg Batchuluun (JINR) -
179
Investigation of heavy-ion fusion reaction with formation of medium mass nuclei at low energies
In low-energy nuclear reaction physics the interactions of 12C, 16O nuclei play an important role at the studies of the stellar nucleosynthesis. The low interaction energies (which are relevant for the processes occurring in the stars) lead to significant difficulties in describing the fusion reaction mechanism for these nuclei. The main problem in this case connected with the resonance structure [1] of studied nuclei and the lowering of the reaction cross section due to the hindrance effect [2].
In this work, the recently proposed approaches [3] were used to describe resonances in the framework of the potential model. The decrease of the cross-section due to hindrance effect was taken into account and the results for possible position of the astrophysical S-factor maximum were obtained using the R-matrix approach with account for the resonances.The reported study was supported by RFBR, research project No. 20-02-00295.
- S.Ohkubo, K.Yamashita, Physics Letters B 578, 304 (2004).
- G. Montagnoli, A. M. Stefanini, C. L. Jiang et al., Phys. Rev. C 101, 044608 (2020).
- S. Yu. Torilov, N. A. Maltsev, V. I. Zherebchevsky, Bull. Russ. Acad. Sci. Phys. 85, 548 (2021).
Speaker: Sergey Torilov (Saint Petersburg State University) -
180
New set of optical parameters for neutron scattering on $^{12}$C nuclei
The project TANGRA is devoted to study of nuclear reactions induced by 14.1-MeV tagged neutrons. Several measurements of $\gamma$-quanta angular distributions were conducted, including the experiment with carbon sample [1]. At the moment it is planned to measure angular distributions of the neutrons scattered on carbon, the results will require model description. An optical model [2] will be used in the analysis of experimental data.
Optical potentials are often used with other methods: the coupled-channel approach (CC) can be used with various nuclear deformations and approaches to handle excited states of the nucleus. In our case, an oblate shape was adopted for $^{12}$C, and the first excited state at 4.44 MeV ($2^+_1$) was considered rotational in CC, as it was proposed in some works. The estimation of $^{12}$C deformation is somewhat ambiguous, the quadrupole deformation parameter $\beta_2$, apparently, depend on type and energy of the probing particle used [3].
To determine the correct optical parameters and $\beta_2$ for $^{12}$C, we developed a specially designed ROOT library, which can iteratively run TALYS [4] calculations and process their results. The potential parameters were obtained by minimizing the deviation of the differential cross sections for elastic and inelastic neutron scattering calculated in TALYS from the experimental data.
The obtained optical potential was used to calculate integral and differential cross sections of the most probable processes occurring in the interaction of 14.1 MeV neutron with $^{12}$C nucleus. The calculated values were compared with experimental data.
- D.N. Grozdanov et al.,Yadernaya Fizika, 81, 548 (2018)
- W.H.Dickhoff and R.J.Charity, Prog. Part. Nucl. Phys. 105, 252 (2019)
- W.J.Vermeer et al, Phys. Lett. B 122, 23 (1983)
- A.J. Koning and D. Rochman, Nucl. Data Sheets, 113, 2841 (2012)
Speaker: Ilya Dashkov (Joint Institute for Nuclear Research, 141980 Dubna, Russia; Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia) -
181
PROBING ISOSCALING TO DETERMINE THE NUCLEAR TEMPERATURE IN LOW-ENERGY FISSION
We examined the bulk of available yields of fission fragments from $Z$=28 to $Z$=67 verifying the applicability of isoscaling for low-energy fission.
The phenomenon of isoscaling indicates the statistical distribution of the energy,
released during the fission process, among the corresponding fission fragments.
This behavior has been already discovered in special cases of fission processes
as described in previous studies (from the first work [1] to the latest one [2]).
In this connection, the yields ($Y_1$,$Y_2$) of specific isotopes with ($N,Z$),
produced in two similar fission reactions, are related by the following equation:
\begin{equation}
\frac{Y_2}{Y_1} = C \cdot exp(\alpha \cdot N + \beta \cdot Z) ,
\end{equation}
where $C$ is a normalisation constant.
The isoscaling parameters ($\alpha$ and $\beta$) were obtained by fits applied to the ratios of fission fragment yields available for 4 different energy classes of low-energy fission processes compiled in ENDF/B-VII.1 data library for fissioning nuclei with atomic numbers from 90 (Th) to 100 (Fm) [3]. The isoscaling parameters are related to the nuclear temperature, the mass and the atomic numbers of the nuclei, undergoing fission, and the symmetry energy coefficient $C_{sym}$. The last magnitude is well known from fits of experimental binding energies achieved within the liquid drop model [4]. The value $C_{sym}$ = 23 MeV, adopted therefrom, is used to evaluate nuclear temperatures which are in rather good agreement with corresponding values obtained by other approaches such as the isotope thermometry [5].
This new approach to extract the nuclear temperature in low-energy fission is described in details.- W.A. Friedman, Phys. Rev. C 69, 031601 (2004).
- J. Drnoyan et al., Phys. Part. Nucl. Lett. 13, 342 (2016).
- https:// www-ndc.iaea.org
- S.R. Souza et al., Phys. Rev. C 667, 051602 (2003).
- M.N. Andronenko et al., Bull. Russ. Acad. Sci.: Phys. 84, 1540 (2020).
Speaker: Dr Lyudmila Andronenko (Petersburg Nuclear Physics Institute of NRC KI) -
182
Study of four-neutron correlations in cluster decay of $^{12}$Be highly-exited states on RADEX channel
Kinematic simulation of simultaneous four-neutron emission at $\alpha$-cluster decay of $^{12}\text{Be}^{*}$ highly-exited states has been considered in $^{13}\text{C}(n,2p)^{12}\text{Be}^{*}$ reaction on RADEX cascade neutron. The cluster decay fragments should have specific energy and angular correlations reflecting strong spatial correlations of "valence" nucleons orbiting in the decay nucleus [1]. The study of characteristics of cluster decay channels is extremely important for studying the cluster properties of various nuclear states [2]. Calculations using the antisymmetric model of molecular dynamics revealed the α-cluster structure of the isotopes $\text{Be}$, $\text{B}$, and $\text{C}$ [3]. In $^{12}\text{Be}$ highly-exited states the possibility the formation of $^{8}\text{Be}$-cluster and a $4n$-correlated cluster with a radius of $\le$ 3 fm in a nuclear field $\ge$ 3 MeV or as a resonance with an energy of 2 MeV in the continuous spectrum [4]. Excitation of the highly-exited $\alpha$-cluster states in $^{12}\text{Be}$ is possible when a proton pair is quasi-elastically knocked out of $^{13}\text{C}$ at an angle of $\sim 15^{\circ}$ by a cascade neutron with an energy of $\ge$ 40 MeV or in an $n-p$ charge exchange reaction followed by rescattering by a proton at an energy $\le$ 100 MeV. In the work a two-stage kinematic simulation of the process of formation and escape of $4n$-correlated cluster in $^{13}\text{C}(n,2p2\alpha)4n$ reaction was carried out. At the first stage, the $^{13}\text{C}(n,2p)^{12}\text{Be}^{*}$ reaction was considered with excitation of double analog state of $^{12}\text{C}$ (Fig. 1a). At the second stage, subsequent $\alpha$-cluster decay of $^{12}\text{Be}^{*}$ on $4n$-correlated cluster and $^{8}\text{Be}$ or $\alpha$-particles was considered.
Estimated parameter of the pulsed source of cascade neutrons at an energy of 40-100 MeV is $10^{13}$ n/s. Calculations show that of two-proton registration from the formation of an excited state of $^{12}\text{Be}^{*}$ is possible in a narrow cone. The decay of the $\alpha$-cluster excited state of $^{8}\text{Be}+4n$ should be recorded at the widest solid angle. The registration of 4-particle coincidence must suppress the background (Fig. 1b).- P.Sharov at al // Int. Conf. "Nucleus-2020", Book of Abstracts, Dubna, 38 (2020).
- D.Rodkin at al // Int. Conf. "Nucleus-2020", Book of Abstracts, Dubna, 51 (2020).
- Y.Kanada-En'yo, K.Ogata. // Phys.Rev.C.2019.V.100.p.064616.
- S.C.Pieper // Argonne, Illinois 60439, USA. 2018, arxiv: nucl-th/0302048v2.
Speaker: Vladimir Skorkin (INR RAS) -
183
Preliminary results of the study of gamma-ray transitions in 11C and 11B nuclei in 9Be(3He,nγ)11C and 9Be(3He,pγ)11B reactions
Excitation functions of gamma-transition in nuclei produced in reactions involving the 3He and 9Be ions are required to reconstruct distributions of fast 3He ions in thermonuclear plasma using gamma-ray spectrometry methods [1]. The distribution of fast ions can be obtained in two following ways: analyzing the gamma-line intensities measured by a gamma-spectrometer and analyzing the shape of the gamma-line broadened by the Doppler effect. The latter method also requires precise semiconductor spectrometers to be used in the measurements. The 3He minority ions are applied to the so-called three-ion ion-cyclotron radiofrequency (ICRF) scenario of tokamak plasma heating [2]. 3He ions accelerated to the MeV-energy range were observed in JET plasma [3]. The obtained data presented in this work will be applied for the analysis of the plasma heating regimes at JET and future facilities such as ITER.
Excitation functions of gamma-transition in 11C и 11B nuclei produced in reactions involving the 3He and 9Be ions were measured on the Cyclotron of Ioffe Institute in the energy range from 1.5 to 6 MeV. A target consisted of beryllium, deposited on a 0.5-mm-thick tantalum substrate, was used in the measurements. The thickness of beryllium is 212 μg/cm2. Gamma radiation was measured by two HPGe spectrometers with a relative efficiency of 49% and 56%. In the first measurements, the line shapes of 6.9-MeV gamma-transition from the 9Be(3He,nγ)11C reaction and 8.92-MeV transition from the 9Be(3He,pγ)11B reaction were obtained at the energy of 3He of 2.57 MeV [4]. In the present work, angular distributions of 2.0-, 4.32- and 6.9-MeV gamma-transitions from the 9Be(3He,nγ)11C reaction and 2.12-, 7.29- and 8.92-MeV transitions from the 9Be(3He,pγ)11B reaction were measured. Furthermore, based on the 7.29- and 8.92-MeV gamma-line shape analysis, the angular distribution of the proton emission upon the population of the corresponding excitation levels of the 11B nucleus was obtained, as well as the angular distribution of the neutron emission upon the population of the 6.9-MeV level of the 11C nucleus. In this work, the preliminary results of measurements of partial cross-sections and angular distributions of gamma quanta, protons and neutrons are presented at different energies of the 3He beam.- V. G. Kiptily, F. E. Cecil, and S. S. Medley, Plasma Phys. Control. Fusion 48 R59 (2006)
- Ye. O. Kazakov et al., Nat. Phys. 13 973–8 (2017)
- V.G. Kiptily et al., Nucl. Fusion 50 084001(2010)
- M.V. Iliasova et al., Tech. Phys. Lett. 47 2 103–106 (2021)
Speaker: Margarita Iliasova (Ioffe Institute) -
184
Analysis for 6Li+12C elastic scattering using different potentials
Experimental angular distributions for the elastic scattering of 6Li projectile on a 12C target have been reanalyzed in the energy range 4.5- 60 MeV. The projectile-target optical potential was calculated phenomenologically with optical model (OM) of Woods-Saxon (WS) potential shape for real and imaginary parts and semi-microscopically using both of double folding approach based on energy dependent São Paulo potential (SPP) and double-folding cluster (DFC) potential. The generated cluster folding potentials is based on the (α-d) structure of 6Li.The theoretical calculations using the different concerned potentials reproduce fairly well the experimental data in the whole energy range.
Speaker: Ahmed Amer (National Research Nuclear University “MEPhI”) -
185
Proton-capture measurements on stored radioactive ions for the p-process nucleosynthesis
Highly-charged stable or radioactive ions can be stored and cooled in a heavy-ion storage ring offering unrivaled capabilities for precision studies of the atomic and nuclear structure, and for astrophysics [1]. We have employed the unique feature of the Experimental Storage Ring (ESR) facility at GSI to address astrophysically relevant reactions for explosive nucleosynthesis, in
particular for the poorly understood production of the rare p-nuclei.
After the successful campaign for (p,γ) measurements on stored stable beams [2-3], within the framework of the experimental program at GSI in 2020 and 2021, the (p, γ) reaction cross-sections have been successfully measured at 10MeV/u, 7 MeV/u and 6 MeV/u beam energies using a radioactive ion beam for the first time, namely 118 Te beam with 6 days half-life. Using a Double Sided Silicon Strip Detector (DSSSD), introduced directly into the Ultra High Vacuum environment of the storage ring, the proton-capture reaction products have been detected. With the application of the newly developed “elimination of the Rutherford elastic scattering” (ERASE) technique the sensitivity for the proton-capture products is maximized.
In this contribution, the experimental method for precision studies of the proton-capture will be introduced with the highlight on the working principle of the ERASE background suppression technique. In addition, preliminary experimental results from the 118 Te(p,γ) 119 I reaction measurement will be discussed in detail.- F. Bosch et al., Prog. Part. Nucl. Phys. 73, 84 (2013).
- B. Mei et al., Phys. Rev. C 92, 035803 (2015).
- J. Glorius et al., Phys. Rev. Lett. 122, 092701 (2019).
Speaker: Dr Laszlo Varga (GSI) -
186
ЦИФРОВАЯ ЭЛЕКТРОНИКА 2.0 ДЛЯ ПОСТРОЕНИЯ ПОЛНОСТЬЮ ОЦИФРОВАННЫХ СИСТЕМ СБОРА И ОБРАБОТКИ ДАННЫХ
Построение цифровых схем для обработки и управления экспериментальными установками за 15 лет с тех пор, как CAEN выпустил на рынок первые диджитайзеры стало, по сути, стандартом. За прошедшие десятилетия сотни средних и крупных экспериментов в мире были выполнены на основе продвигавшейся CAEN парадигмой цифрового подхода. Это и эксперименты по исследованию тёмной энергии, гамма-сферы, построенные за эти годы во многих странах мира, эксперименты по нейтринным осцилляциям, эксперименты на различных токамаках, ядерных реакторах, астрофизика, исследования ядерных распадов и многое-многое другое.
Растущие сложность экспериментов приводят к появлению всё новых требований к цифровой электронике. Они уже не ограничиваются роста скоростей оцифровки, или ростом скорости передачи и обработки данных. Растущие объёмы данных делают всё более и более заманчивой идею не переносить данные на компьютер, а обрабатывать их прямо на железе, непосредственно во время сбора данных. Проблемой тут встаёт либо невозможность изменять встроенную в ПЛИС прошивку, либо требования к написанию сложного низкоуровнего кода для работы с ПЛИС.
Мы рады представить научному сообществу 2-е поколение DIGITIZERS 2.0, которое решает все стоящие перед современным научным сообществом задачи.
- Больше скорости оцифровки
- Большая битность сигнала
- Большие объёмы памяти
- Большие скорости передачи данных
- Большая плотность каналов
- Возможность легко изменять прошивки ПЛИС и обрабатывать данные на самом диджитайзере.Speaker: Ivan Bredikhin
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PlenaryConvener: Grigori Feofilov (St Petersburg State University (RU))
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187
Overview of CMS results
In this overview, the physics highlights of the CMS results are presented, with a focus on the latest results obtained with the full LHC Run 2 statistics.
Speaker: Sergei Shmatov (Joint Institute for Nuclear Research (RU)) -
188
Highlights of recent results from ATLAS
Recent results from ATLAS will be presented. These include highlights of heavy ion physics as well as measurements of properties of the Higgs boson and the top quark, diboson production, and searches for supersymmetry and exotics.
Speaker: Christopher John Meyer (Indiana University, US) -
189
Overview of LHCb results
The LHCb detector at the LHC specialises in studying decays of beauty and charm hadrons, with excellent tracking, secondary vertex reconstruction and particle identification capabilities.
Here we present an overview of recent highlighted results from the broad physics programme at LHCb, including the flavour anomalies and precise determination of CKM parameters. Specific attention is paid to the topic of hadron physics, covering both exotic and conventional hadron spectroscopy.
Speaker: Adam Morris (University of Bonn) -
190
Recent results with ALICE at the LHC
A Large Ion Collider experiment (ALICE) at the LHC allows to study different aspects of strong interaction physics. This talk gives an overview of its experimental programme based on selected recent results.
Measurements based on jets and hadrons containing charm and beauty quarks at the LHC allow to constrain the interaction between the quark-gluon plasma and partons, to learn about radiation in quantum chromodynamics and about hadronisation in different environments. We discuss new results on these topics in proton-proton, proton-nucleus and nucleus-nucleus collisions.
The highly relativistic collisions involving charged ions at the LHC allow to identify photon-induced interactions. Recent ALICE measurements as a probe of hadron structure and the initial state of heavy-ion collisions are presented.
Collisions at ultra-relativistic energies at the LHC produce large numbers of hadrons and nuclei of variable light-flavour quark content. They can be used to perform production and correlation measurements sensitive to the production mechanisms and the inter-particle interactions. Furthermore, the detector material can be used to study particle absorption cross sections. The talk will show unique measurements provided by ALICE and mention their connection to other fields as the equation of state of neutron stars and dark matter searches in space.Speaker: Michael Andreas Winn (Université Paris-Saclay (FR)) -
11:20 AM
Coffee break
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191
Overview of heavy-ion results from CMS
Recently, CMS collaboration presented important results to widen our knowledge of Quark-Gluon-Plasma (QGP) state, known as the state of the early universe, by using high energy heavy ion collisions. In this presentation, I would like to introduce them and share the detailed news including hard and soft probes produced in the heavy ion collisions at $\sqrt{s_{NN}}$ = 5.02 TeV and analyzed with Run ll data, corresponding luminosity to 1.7nb$^{-1}$.
Speaker: Dong Ho Moon (Chonnam National University (KR)) -
192
Present and future upgrades of ALICE
ALICE is currently completing major upgrades for LHC Run 3 and in the meantime further projects are already underway. ALICE is developing thinned wafer-sized monolithic active pixel sensors to replace the inner tracking layers during the Long Shutdown 3. This resulting detector will have an unprecedented low material budget, and consequently drastically reduced interaction probabilities and unparalleled vertexing performance. Furthermore, we plan to install a Forward Calorimeter (FoCal) comprising a Si-W electromagnetic calorimeter with pad and pixel readout and a hadronic calorimeter with conventional metal-scintillator technology with optical readout, covering 3.4 < eta < 5.8. Finally, a proposal of a next-generation heavy-ion experiment for LHC Run 5 is also in preparation and will be discussed. This new apparatus foresees an extensive usage of thin silicon sensors for tracking and a modern particle identification system, combining a silicon-based time of flight detector, a RICH and preshower detector. The advantages of extremely low material budget, fast read-out and high resolution will enable novel measurements of electromagnetic and hadronic probes of the QGP at very low momentum.
Speaker: Stefania Beole (Universita e INFN Torino (IT)) -
193
CMS detector upgrade
The CMS Upgrade projects, both Phase-1 and Phase-2, are aimed for the improvement of detector systems to provide the necessary physics performance under the challenging conditions of high luminosity at the HL-LHC. In this second phase of the LHC physics program, it's being planned to increase the instantaneous luminosity by $5.0^{34}$ cm$^{−2}$ s$^{−1}$ with the goal of integrating some 3000 fb$^{−1}$ by the end of 2037. The corresponding mean number of collisions (pileup) per bunch crossing will be 140, with the possibility to increase it up to 200. Installation of the upgraded detector systems started in LS2 and is planned to be completed in LS3, presently scheduled for 2025 to mid-2027. CMS detectors need to be modernised in order to improve the ability to isolate and precisely measure the products of the most interesting collisions.
Speaker: Pavel Bunin (Joint Institute for Nuclear Research (RU)) -
194
Nuclear Physics at ISOLDE-CERN
The ISOLDE Facility at CERN is the world’s leading facility for the production of radioactive ion beams (RIBs) using the ISOL (Isotope Separation On-Line) method. Over 1000 isotopes of more than 70 elements have been produced by the impact of a 1.4 GeV proton beam on a variety of targets and using different ion sources for providing beams at 40-50 keV energy. Purified isotope/isomer beams can be further accelerated to about 10 MeV/u using the HIE-ISOLDE post-accelerator.
The low-energy and accelerated beams are used for a wide variety of experiments in nuclear structure research, but also for studying astrophysical processes, for materials properties research, for biochemical and biomedical research and for fundamental interaction studies.
This presentation will introduce the ISOLDE facility and RIB production, including some recent examples of experiments addressing open questions in nuclear physics.Speaker: Sean John Freeman (Experimental Physics Department, CERN, Switzerland; University of Manchester, UK)
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2:00 PM
Lunch break
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Section 1. Experimental and theoretical studies of the properties of atomic nuclei: Few-Body Problem in Physics: Theory and Solution MethodsConvener: Sergey Yakovlev (St Petersburg State University)
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195
Study of light nuclei within the SS-HORSE-NCSM approach
We present investigations of resonant states of exotic $^7$He nucleus and calculations of bound states and resonances of $^9$Li nucleus. Our results are obtained within an analysis of the $S$-matrix based on calculations within the no-core shell model (SS-HORSE-NCSM approach [1, 2]) using the realistic nucleon-nucleon interaction Daejeon16 [3].
Results for the $5/2^-$ and low-lying $3/2^-$ resonances in $^7$He are in reasonable agreement with experiment. There is a contradictory experimental information about energy and width of the $1/2^-$ resonance in $^7$He. In our calculations, the energy $E_{r}$ of this resonance is 2.7 MeV and the width $\Gamma$ is about 4 MeV. We predict in $^7$He also wide overlapping resonances $3/2^-$, $3/2^+$ and $5/2^+$ with energies around 4-5 MeV which are supposed to form an experimentally observed wide resonance at 6 MeV of unknown spin-parity.
The binding energy of the $^9$Li ground state is in reasonable agreement with experimental data. The calculated excitation energy of the first exited state of $^9$Li is 3.54 MeV which is larger than the experimental value of 2.691 MeV. We predict in our approach also the asymptotic normalization coefficients for these bound states. Experimentally there are $^9$Li resonances of unknown spin-parity with $E_r=0.232$ MeV and $\Gamma=0.1$ MeV and $E_r=1.316$ MeV and $\Gamma=0.6$ MeV; we obtain $^9$Li resonant states $5/2^-$ ($E_r=0.27$ MeV, $\Gamma=0.21$ MeV) and $3/2^-$ ($E_r= 1.53$ MeV, $\Gamma=2.39$ MeV).
References:
-
A. M. Shirokov, A. I. Mazur, I. A. Mazur and J. P. Vary, Phys. Rev. C 94, 064320 (2016).
-
A. M. Shirokov, A. I. Mazur, V. A. Kulikov, Phys. At. Nucl. 84, 131 (2021).
-
A. M. Shirokov, I. J. Shin, Y. Kim, M. Sosonkina, P. Maris and J. P. Vary, Phys. Lett. B 761, 87 (2016).
Speaker: Dr Igor Mazur (Pacific National University, Khabarovsk, Russia; University of Korea, Seoul, Republic of Korea) -
-
196
Incoming wave bondary conditions in sub-barrier heavy ion fusion reactions
We analyze sub-barrier heavy ion fusion reactions based on the coupled-channels description with the correct incoming wave boundary conditions, implemented by means of the finite element method. With the aid of the Woods-Saxon potential
the experimental cross sections and the so-called S factors of these reactions are remarkably well reproduced within the sudden approximation approach with the correct incoming wave boundary conditions. We found that accounting for the nondiagonal matrix elements of the coupling matrix, traditionally neglected in the
conventional coupled-channels approaches in setting the entangled left boundary conditions inside the potential pocket, and its minimal value are crucially important for the interpretation of experimental data.Speaker: Sergue Vinitsky -
197
THREE-BODY SCATTERING IN THE TOTAL ANGULAR MOMENTUM REPRESENTATION
Scattering problem for three-body systems is of great importance for many areas of physics. The complicated boundary conditions at large distances, especially for Coulomb potentials, are a major difficulty for studying of this problem [1]. While several methods have been developed for the solution to this problem, mathematically sound and computationally effective approaches are still in demand.
In this report, we present an approach based on splitting the reaction potential into a short-range part and a long range tail part to describe few-body scattering in the case of the Coulomb interaction [2,3]. The solution to the Schroedinger equation for the long range tail of the reaction potential is used as an incoming wave. This reformulation of the scattering problem into an inhomogeneous equation with asymptotic outgoing waves makes it suitable for solving with the exterior complex scaling technique. The potential splitting approach is illustrated with calculations of scattering processes in systems with non-zero angular momentum. The accuracy of the approach is analyzed.
- L.D. Faddeev, S.P. Merkuriev, Quantum Scattering Theory for Several Particle Systems. Kluwer, Dordrecht (1993).
- M.V. Volkov, E.A. Yarevsky, S.L. Yakovlev, Europhys. Lett. 110, 30006 (2015).
- E. Yarevsky, S.L. Yakovlev, N. Elander, J. Phys. B: At. Mol. Opt. Phys. 50, 055001 (2017).
Speaker: Evgeny Yarevsky (St Petersburg State University) -
198
Direct calculation of quasi-stationary states of the neutron plus nonspherical nucleus system.
The states of the Be$^{11}$ nucleus as a core of Be$^{10}$ plus a neutron are studied in [1, 2], as well as many others. The Be$^{10}$ nucleus is an almost ideal object for studying the effects associated with the non-spherical shape of the nucleus. It has the largest deformation parameter for stable and long-lived nuclei. Usually the coupled channel method is used, the problem is reduced to a system of equations in a spherical symmetric field. In this work the method of direct solution of scattering by an axially symmetric potential has been used. Resonances in scattering, which are obviously also quasi-stationary states, have been calculated.
The differences arising from these two approaches are shown. The main effect is the nature of the resonances. Resonances are the result of the interaction of a nuclear potential and an analogue of a centrifugal potential. This follows from a direct calculation using the axial symmetry of the problem. The resonances here are equivalent to the states of a complex nucleus, which is a neutron and a deformed core.
This work was supported by the Grant No. BR09158499 (Development of complex scientific research in the field of nuclear and radiation physics on the basis of Kazakhstan accelerator complexes) of the Ministry of Energy of the Republic of Kazakhstan.- H. Esbensen, B. A. Brown, and H. Sagawa Phys. Rew. C 51, (1995), 1274-1279
- I Hamamoto and S Shimoura J. Phys. G: Nucl. Part. Phys. 34 (2007) 2715–2725
Speaker: Pavel Krassovitskiy (Join institute for nuclear research) -
4:40 PM
Coffee break
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199
Theoretical Study of Weakly-Bound Triatomic Systems with Discrete Variable Representation method
The interest to weakly-bound triatomic systems is stimulated by their connection with Efimov physics. There is a variety of systems including helium and helium-alkali triatomic molecules [1] whose states are close to Efimov regime. Some of these systems have bound states with nonzero orbital momentum. These latter states are much less studied than the states with the zero angular momentum.
Another interesting problem is connected with possible resonance states of systems under discussion. Study of resonance states is an interesting area of few-body quantum physics [2]. Resonance states are usually associated with the poles of the analytic continuation of the resolvent or $S$-matrix. There exist various methods of their calculations. In this work, the complex rotation method [3] is used.
Both above mentioned problems result in additional computational complexity, so a computationally effective approach is required. To speed up calculations, we use the discrete variables representation [4] based on the basis of functions, which are in some way localized on the grid in the angular space. The method has been generalized to complex functions to make it applicable to calculation of resonance states.
In this report, the bound and resonance energies of few weakly-bound triatomic systems including He${}_2$Li and He${}_2$Na have been calculated with the variational approach and the DVR expansion. The results are compared with results of other authors.
This research was supported by Russian Science Foundation grant No. 19-32-90148.
Research was carried out using computational resources provided by Resource Center "Computer Center of SPbU" (http://cc.spbu.ru).-
H. Suno et al., Few-Body Syst. 54, 1557 (2013).
-
V.I. Kukulin et al., Theory of Resonances, Springer:Dordrecht, 347 (1989).
-
B. Simon Phys. Lett. 71A, 211 (1979).
-
J.C. Light, T.Jr. Carrington, Adv. Chem. Phys. 114, 263 (2000).
Speaker: Vladimir Timoshenko (Saint-Petersburg State University) -
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200
DETERMINATION OF ASYMPTOTIC NORMALIZATION COEFFICIENTS BY ANALYTIC CONTINUATION OF DIFFERENTIAL CROSS SECTIONS
Asymptotic normalization coefficients (ANC) are fundamental nuclear characteristics important both in nuclear reaction and nuclear structure physics. The role of ANCs is especially substantial in determining the cross sections for astrophysical nuclear reactions inaccessible for direct measurement due to the large Coulomb barrier [1]. ANCs are on-shell observables, as distinct from the spectroscopic factors which are off-shell quantities and cannot be reliably extracted from experimental data.
In the present work, we discuss the possibility of determining ANCs by analytic continuation of the differential cross sections of transfer reactions to the pole point in the scattering angle $\theta$ lying in the unphysical region $\cos \theta>1$. Special attention is paid to the corrections to the pole contribution to the differential cross section due to the Coulomb interaction in the initial and final states of the reaction (see [2] and references therein). The role is discussed of kinematic singularities arising in the case of nonzero orbital angular momenta at the vertices of the pole diagram, which determines the transfer mechanism. The discussed method was applied to the reaction ${ }^{12} \mathrm{C}(d, p){ }^{13} \mathrm{C}^{*}\left(1 / 2^{+} ; 3.09 \mathrm{MeV}\right)$. Five experimental differential cross sections corresponding to the deuteron energy in the range of $5-30 \mathrm{MeV}$ were used to determine the important ANC $C$ for the vertex ${ }^{13} \mathrm{C}^{*} \rightarrow{ }^{12} \mathrm{C}+n$ by analytic continuation. The $C$ values obtained from the analysis of the $(d, p)$ reaction at different energies turned out to be close to each other. The average value of the squared ANC obtained by the method of analytic continuation with account of the Coulomb corrections is $C^{2}=3.52 \mathrm{fm}^{-1}$.
This work was supported by the Russian Foundation for Basic Research grant No. 19-02-00014.
References:
1. A.M.Mukhamedzhanov, N.K.Timofeyuk, Sov. J. Nucl. Phys. 51, 431 (1990).
2. L.D.Blokhintsev, A.M.Mukhamedzhanov, A.N.Safronov, Sov. J. Part. Nucl. 15, 580 (1984).Speaker: L.D. Blokhintsev (Lomonosov Moscow State University) -
201
Optimal bounds on the quantum speed of subspace evolution
By a quantum speed limit one usually understands an estimate on how
fast a quantum system can evolve between two distinguishable states.
The most known quantum speed limit is known in the form of the
celebrated Mandelstam-Tamm inequality that bounds the speed of the
evolution of a state in terms of its energy dispersion. In contrast
to the basic Mandelstam-Tamm inequality, we are concerned not with a
single state but with a (possibly infinite-dimensional) subspace
which is subject to the Schr\"odinger evolution. By using the
concept of maximal angle between subspaces we derive optimal bounds
on the speed of such a subspace evolution. These bounds may be
viewed as further generalizations of the Mandelstam-Tamm inequality.
In the present work we extend some of our previous results [1] to
the case of unbounded Hamiltonians.This is a joint work with Sergio Albeverio.
[1] S.Albeverio and A.K.Motovilov, Quantum speed limits for
time evolution of a system subspace, arXiv:2011.02778 (2020) [8
pages].Speaker: Prof. Alexander K Motovilov (JINR) -
202
Spectral density for a discretized continuum
Different approaches which employ discretization of continuum, for example, by projecting the operators and wave functions into some finite $L_2$ basis, are widely used nowadays as efficient techniques to solve the scattering problems. Here we discuss how to extract information about scattering from the discretized spectra of unperturbed and total Hamiltonians. It is shown that if the discrete eigenvalues $E_j$ lie on some smooth curve $\lambda(x)$ (i.e. $E_j=\lambda(x=j)$) then one can construct a smooth integrated spectral density (ISD) for the corresponding Hamiltonian by using the inverse function. The difference of ISDs for the total and unperturbed Hamiltonians gives the spectral shift function which is proportional to the scattering phase shift. Also, one can define separate spectral densities for the Hamiltonians as derivatives of the above ISDs. Although each spectral density doesn’t correspond to the initial continuous spectrum and depends on the way of the discretization, the difference of these densities for the total and unperturbed Hamiltonians does define a proper continuum level density (CLD) for the initial problem in question. In particular, this CLD can be used to find resonances in the system. Thus, a rather simple treatment of discretized spectra of unperturbed and total Hamiltonians allows to find scattering observables in a wide energy region without solving scattering theory equations.
The approach represents a generalization of the discrete spectral shift method [1,2] developed by the authors previously. As illustrations, we consider several examples from atomic and nuclear physics, including p-$^{12}$C scattering, by using the Gaussian basis representation. Also, relations between the suggested method and the known approaches, such as the SS-HORSE [3] and the $R$-matrix, are discussed.- O.A. Rubtsova, V.I. Kukulin, V.N. Pomerantsev, A. Faessler, Phys. Rev. C 81, 064003 (2010).
- O.A. Rubtsova, V.I. Kukulin, V.N. Pomerantsev, Phys. At. Nucl. 77, 486 (2014).
- A.M. Shirokov, A.I. Mazur, I.A. Mazur, J.P. Vary, Phys. Rev. C 94, 064320 (2016).
Speaker: Dr Olga Rubtsova (Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics) -
203
HYPER-RADIAL ASYMPTOTIC OF THE WAVE FUNCTION OF THREE PARTICLES WITH COULOMB INTERACTION IN THE CONTINUUM
The asymptotic form of the wave function of a three-particle system interacting via Coulomb potentials in the continuum is described. The hyperradial asymptotic behavior of the wave function is found by study the weak asymptotic of the three-body wave function [1,2] and then applying to the asymptotic solutions of the Schroedinger equation in the hyper-spherical representation. The perspective of applications to the analysis of the few nucleon system is discussed.
- S.L. Yakovlev, Theor. Math. Phys. 186 (1): 126 (2016)
- S.L. Yakovlev, Theor. Math. Phys. 206 (1): 68-83 (2021)
Speaker: Prof. Sergey Yakovlev (St Petersburg State University)
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195
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Section 2. Experimental and theoretical studies of nuclear reactionsConveners: Agniya Zvyagina (Saint Petersburg State University), Alexaner Zharov (Saint Petersburg State University, Russia)
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3:00 PM
Beginning of the session
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204
DATA ANALYSIS FROM CATCHER FOIL EXPERIMENT FOR CROSS SECTIONS MESUREMENT OF 40Ar + 144Sm REACTION
Cross sections from the complete fusion reaction of 40Ar + 144Sm were measured by the catcher foil method [1] (on the U400M cyclotron at the Flerov Laboratory of Nuclear Reactions). The catchers were made out of five aluminum foils (0.8 µm thick) stacked downstream from the target. The experiment was carried out in repetitive short cycles (10 s). The foils were periodically moved from the beam position to the detector position. Data from the detector were analyzed to obtain α-spectra of implanted isotopes. A new method of data analysis was proposed in the work taking into account TRIM [2],[3] and Geant4 [4]Monte-Carlo simulations for alpha spectra, PACE4 [5]fusion-evaporation code for residual nuclei energy distribution, Couple channel method calculation [6] for theoretical cross sections and SRIM [3] evaluation of produced isotopes stopping ranges. Using this method the 1pxn, 2pxn and 1αxn complete-fusion excitation functions are presented.
[1] G. M. & W. R. D. Vermeulen, H. -G. Clerc, C. -C. Sahm, K. -H. Schmidt, “Cross sections for evaporation residue production near the N=126 shell closure,” Z. Phys. A - Atoms Nucl., vol. 318, pp. 157–169, 1984.
[2] J. P. Biersack and L. G. Haggmark, “A Monte Carlo computer program for the transport of energetic ions in amorphous targets,” Nucl. Instruments Methods, vol. 174, no. 1–2, pp. 257–269, 1980.
[3] J. F. Ziegler, M. D. Ziegler, and J. P. Biersack, “SRIM - The stopping and range of ions in matter (2010),” Nucl. Instruments Methods Phys. Res. Sect. B, vol. 268, no. 11–12, pp. 1818–1823, 2010.
[4] S. Agostinelli et al., “GEANT4 - A simulation toolkit,” Nucl. Instruments Methods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip., vol. 506, no. 3, pp. 250–303, 2003.
[5] O. B. Tarasov and D. Bazin, “LISE++: Exotic beam production with fragment separators and their design,” Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms, vol. 376, pp. 185–187, 2016.
[6] V. Karpov et al., “NRV web knowledge base on low-energy nuclear physics,” Phys. At. Nucl., vol. 79, no. 5, pp. 749–761, 2016.Speaker: Mr Antonín Opíchal (Flerov Laboratory of Nuclear Reactions, JINR; Department of Experimental Physics, Faculty of Science, Palacky University) -
205
Production cross sections of mercury and radon isotopes in complete fusion reactions with 36,40Ar and 40,48Ca projectiles
The complete fusion - excitation functions of xn-evaporation channels of the reactions 144Sm(40Ar, xn){184-x}Hg, 148Sm(36Ar, xn){184-x}Hg, 144Nd(40Ca, xn)^{184-x}Hg, 142Nd(48Ca, xn)^{190-x}Hg, and 166Er(40Ar, xn)^{206-x}Rn have been measured by using the catcher foil method [1]. A modified version this technique was applied allowing to measure decay properties of α-radioactive nuclides with half-lives ≥ 0.1 s. The beam interruption method was used for the isotope identification. The influence of the beam energy spread at its passing through absorbing foils and the target layer on the excitation functions has been taken in account using the Gold deconvolution method [2]. The measured excitation functions have been compared with theoretically calculated with the coupled-channel model [3,4]. The influence of both the target and projectile nucleus deformations on the final xn-evaporation channel cross sections has been analyzed.
References
1. D. Vermeulen et al., Z. Phys. A 318, 157 (1984)
2. M. Morhac et al., Nucl. Instr. Meth. A 401, 385 (1997)
3. V.I. Zagrebaev, V.V. Samarin, Physics of Atomic Nuclei, 67, 1462 (2004)
4. A.V. Karpov et al., Nucl. Instr. Meth. A 859, 112 (2017)Speaker: Dr Elena Chernysheva (Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research) -
206
DETERMINATION OF PHOTONEUTRON PRODUCTION FROM DIFFERENT TARGETS IRRADIATED BY ELECTRON BEAM
This research focused on photoneutron production determination using two different photoneutron converters BeO, D2O. Experiment was carried out on a linear electron accelerator [1] in A. Alikhanyan National Laboratory in Yerevan, Armenia. A set of targets was irradiated by 70MeV electron beam. Reaction rates were determined as a result of investigations. Besides experimental results, a number of simulations were also conducted using MCNP software [2] to determine reaction rates and they were compared with ones obtained from the experiment.
REFERENCES
1. A.Sirunyan, A.Hakobyan, G.Ayvazyan, et al. LUE-75 Linear Accelerator Facility at Yerevan Physics Institute. J. Contemp. Phys. 53, 271–278 (2018). https://doi.org/10.3103/S1068337218040011
2. C.J.Werner(editor), "MCNP Users Manual - Code Version 6.2", Los Alamos National Laboratory, report LA-UR-17-29981 (2017).Speaker: Elmira Melyan (Brno University of technology) -
4:40 PM
Coffee break
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207
Study of reactions with proton emission at Emax = 20 MeV on natural and enriched hafnium targets
The study of the cross-sections and yields for the population of high-spin isomeric states in reactions with the charged particles emission makes it possible to get information on the exciting levels’ structure in the continuous and discrete regions of excitation as well as on the mechanisms of the nuclear reaction occurrence. Therefore, our work aims to investigate the production yields of Lu-(179m+g) and Lu-178m in reactions with bremsstrahlung gamma quanta for energies in the giant dipole resonance region.
The weighted average yields were measured by the activation method using γ-quanta bremsstrahlung for electrons with the 20 MeV maximum energy on targets of natural metallic hafnium and enriched hafnium Hf-180 in powdery form.
The spectra of irradiated targets were measured by the Canberra and Ortec HPGe spectrometers with the (15-40)% detection efficiency compared to the 3'×3'' NaI (Tl) detector. The spectrometers’ energy resolution was 1.8–2.0 keV on the Co-60 1332 keV γ-line.
The gamma transitions from the Lu-(179m+g) and Lu-178m decays are reliably distinguished in the studied spectra.
The Lu-179m+g weighted average population yield was measured for the (γ, p)-reaction on Hf-180, and Lu-178m weighted average population yield was measured for the (γ, p)-reaction on natural hafnium at the 20 MeV maximum value of the γ-ray bremsstrahlung for the first time.
The following values of the weighted average yields were obtained: for 180Hf(γ, p)179m + gLu-reaction 185(49) μbn, for 179Hf (γ, p) 178mLu -reaction 12.7 (21) μbn.
We stated the dominance of non-statistical processes as a modeling result within the framework of the TALYS-1.9 program code. The obtained data are discussed.
This research was performed according to the Development program of the Interdisciplinary Scientific and Educational School of Lomonosov Moscow State University «Photonic and Quantum technologies. Digital medicine».Speaker: Dr Andrij Savrasov (Institute for Nuclear Research of National Academy of Sciences of Ukraine ) -
208
Study of photonuclear reactions with the charged particles emission for the zirconium-89 production
Zirconium-89, with a half-life of 3.3 days, is one of the most promising radioisotopes for nuclear imaging based on monoclonal antibodies (Immuno-PET). Immuno-PET studies require that the half-life of the diagnostic radioactive isotope coincide with the biological half-life of the carriers (monoclonal antibodies), which exceeds 24 hours and averages 2-6 days. Thus, the half-life of 89Zr ideally matches the half-life of antibodies, and the average positron energy of 395 keV allows for high-resolution PET images.
Currently, the production of Zr-89 is carried out mainly in reactions with protons and deuterons. Accelerators of these particles are complex and expensive to maintain. A promising method for obtaining zirconium-89 is the use of widespread and economic electron accelerators.
However, it is tough to obtain the required radionuclide from the 90Zr(γ, n)89Zr reaction. It is difficult to isolate the Zr-89 from an irradiated zirconium matrix. Therefore, we have carried out studies of reactions with the emission of alpha particles. We studied (γ, αn) and (γ, α)-reactions on natural molybdenum, molybdenum enriched in the 94Mo isotope, natural zirconium, and natural niobium.
The experimental weighted average yields of the reactions under study at the boundary energy of bremsstrahlung gamma quanta of 20 MeV are as follows:
90Zr(γ,αn)85Sr: 0.030 ± 0.015 mbn
96Zr(γ,αn)91Sr: 0.15 ± 0.05 mbn
93Nb(γ,αn)88Mo: 1.16 ± 0.12 mbn
93Nb(γ,αn)88Mo: 0.97 ± 0.10 mbn
94Mo(γ,αn)89Zr: 1.04 ± 0.09 mbn
100Mo(γ,αn)95Zr: 0.03 ± 0.01 mbn
99Mo(γ,α)88Zr: 0.081 ± 0.009 mbn
The obtained data are discussed.
The reported study was funded by RFBR according to the research project 20-315-90124.Speaker: Mr Pavel Remizov (Lomonosov Moscow State University) -
209
Study of (γ, p)-reactions on tungsten isotopes
The study of the cross-sections and yields of (γ,p)-reactions allows one to obtain information on the structure of excited levels in the continuous and discrete regions of excitation and the mechanisms of the nuclear reactions’ occurrence. Our work aims to study the yields of Ta-185,183,182 in reactions with the proton emission for irradiated targets by the bremsstrahlung gamma quanta with energies in the region of giant dipole resonance.
The study of the weighted average yields was carried out by the activation method on a bremsstrahlung γ-beam for electrons with the 20 MeV maximum energy on natural tungsten targets.
The spectra of irradiated targets were measured on Canberra and Ortec HPGe gamma spectrometers with the (15-40)% detection efficiency compared to the 3'×3' NaI(Tl) detector. The energy resolution of the spectrometers was 1.8–2.0 keV on the Co-60 1332 keV γ-lines.
The gamma transitions from the Ta-185,183,182 decay are reliably distinguished in the spectra.
The weighted average yields of the reactions 186W(γ,p)185Ta, 184W(γ,p)183Ta, and 183W(γ,p)182Ta have been measured on natural tungsten targets at the 20 MeV maximum energy of bremsstrahlung photons for the first time.
The following values of the weighted average yields were obtained: for 186W(γ,p)185Ta-reaction 0.70(7) mbn, for 184W(γ,p)183Ta-reaction 1.8(3) mbn, and for 183W(γ,p)182Ta-reaction 3.9(13) mbn. We can state the dominance of non-statistical processes as a modeling result within the TALYS-1.9 program code framework. The theoretical weighted average yields were significantly lower than the experimental values. The obtained data are discussed.Speaker: Prof. Viktor Zheltonozhsky (Lomonosov Moscow State University) -
210
Potentials for $\alpha$+$^{116,122,124}$Sn elastic scattering
The present work reports the analyses of the experimental angular distributions of $\alpha+^{116,122,124}$Sn elastic scattering in terms of the non-monotonic (NM) and modified single-folded (MSF) potentials. These two types of optical model (OM) potentials have enjoyed success in explaining the $\alpha$-induced elastic scattering and non-elastic processes on several targets [1-4]. The NM potential is a complex potential having a soft repulsive core in its real part which has its root in the energy-density functional (EDF) theory of Brueckner, Coon and Dabrowski (BCD) [5]. The MSF potential, on the other hand, is a semi-microscopic single-folded potential [4] based on the combined distributions of $\alpha$-like clusters and unclustered nucleons in the target. Empirically adjusted imaginary potentials are used in conjunction with the real potential to reproduce the experimental $\alpha+^{116,122,124}$Sn elastic scattering data. Two sets of real NM potentials have been found through the analysis using the unshifted and shifted repulsive cores respectively termed as Set-1 and Set-2 potentials. The volume integral per nucleon pair for the real part of the Set-1 and Set-2 potentials has been found to be ~100 MeV.fm$^{3}$ which is normally expected for the NM potential. The closeness of the fits to the data using the real potential with unshifted repulsive core and with shifted repulsive core suggests that the effect of the potential shape in the central region of the target is not that significant in determining the cross-sections and the scattering is dominated by the nuclear potential at the surface of the target nuclei. The MSF potential, without any renormalization, satisfactorily describes the $\alpha+^{116,122,124}$Sn elastic scattering data for the energies considered herein. The number of nucleons making -like clusters is deduced as $4A_{\alpha}=88$ for all the three isotopes of Sn, while the number of unclustered nucleons has been found as $A_N=28$, 34, and 36 for $^{116}$Sn, $^{122}$Sn, and $^{124}$Sn respectively in the time-average picture.
A. S. B. Tariq et al., Phys. Rev. C 59(5), 2558 (1999).
M. N. A. Abdullah et al., Eur. Phys. J. A 18, 65 (2003).
S. Hossain et al., J Phys G: Nucl. Part. Phys. 40, 105109 (2013).
M. N. A. Abdullah et al., Phys. Lett. B 571, 45 (2003).
K. A. Brueckner, S. Coon, J. Dabrowski, Phys. Rev. 168, 1184 (1968).Speaker: Prof. M. Nure Alam Abdullah (Department of Physics, Jagannath University, Dhaka 1100, Bangladesh) -
6:35 PM
End of session
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3:00 PM
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physics: Higgs physicsConvener: Andrey Seryakov (St Petersburg State University (RU))
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211
CMS Higgs results
The Higgs boson within the Standard Model (SM) has been discovered by the ATLAS and CMS experiments in 2012. However analyzing a larger volume of LHC dataset collected by the CMS detector from 2016 to 2018 at a higher center of mass energy ($\sqrt{s}$ = 13 TeV) is expected to shed more light on the Higgs boson properties and would improve the related measurement sensitivity. Few comprehensive analysis on the Higgs decaying to different standard model particles(including all possible Higgs production modes) using the Run 2 dataset of $137 \text{fb}^{-1}$, recorded by the CMS experiment would be presented here. The sensitivity of the analyses are improved by categorizing the events based on different Higgs production mechanisms: Gluon-Gluon fusion (GGH), Vector Boson Fusion (VBF), Vector Boson associated production (VH) and top quark associated production (ttH, tH). Combining all production modes, the latest Higgs boson signal strength measured in $H\rightarrow \gamma \gamma$ decay channel is to be $1.02_{-0.09}^{+0.11}$ with respect to the corresponding SM predictions. Also the measurements of other properties like standard model signal strength modifiers, production cross sections, and its couplings to other Standard Model particles will also be presented.
Speaker: Prafulla Saha (National Institute of Science Education and Research (IN)) -
212
Higgs boson measurements in its decays into bosons with the ATLAS experiment
With the full LHC Run 2 pp collision dataset collected at 13 TeV, very detailed measurements of Higgs boson properties can be performed using its decays into bosons. This talk presents measurements of Higgs boson properties using decays into bosons and their combination with fermionic decays, including production mode cross sections and simplified template cross sections, as well as their interpretations.
Speaker: Heng Li (University of Science and Technology of China (CN)) -
213
Higgs boson measurements in couplings to quarks and leptons with the ATLAS experiment
Testing the Yukawa couplings of the Higgs boson to quarks and leptons is important to understand the origin of fermion masses. The talk presents several new measurements in Higgs boson decays to two bottom quarks or two tau leptons, searches for Higgs boson decays to two charm quarks or two muons, as well as indirect constraints of the charm-Yukawa coupling. The production of Higgs bosons in association with top quarks will also be discussed. These analyses are based on pp collision data collected at 13 TeV.
Speaker: Yasuyuki Horii (Nagoya University (JP)) -
214
CMS Top Results
As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. Top quarks are involved in many beyond standard model (BSM) physics. Due to comparatively higher statistics than Tevatron, CMS has been able to and continuously doing precise measurements on top-quark properties for thorough scrutiny of standard model (SM) and search for new physics. This talk will be focused on the different measurements done on Top quark on CMS.
Speaker: Aloke Kumar Das (National Institute of Science Education and Research (IN)) -
4:40 PM
Coffee break
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215
Searches for heavy Higgs bosons in the framework of 2HDM model
Difficulties associated with the multiplicity of particle production in proton collisions at the LHC and with theoretical description of hadronization lead to assumptions about a new physics in studying the angles of escape and energy of jets. Problems of such physics are connected with the vacuum properties related to the hierarchy problem. The explanation of difficulties of Standard Model (SM) is realized within the theories beyond SM, one of which is Supersymmetry (SUSY). The most promising SUSY model is 2-Higgs-Doublet Model (2HDM) [1]. In the framework of 2HDM model we presented the searches for heavy neutral and charged Higgs bosons, which are performed through the calculations of production cross sections using MadGraph5aMC@NLO program [2] with ansatz of Yukawa coupling and the restricted parameter space connected with LHC Run 2 data [3, 4]. The searches for heavy resonances are performed over the mass range 0.1–1 TeV for the $p p \to A t\overline{b}$, $p p \to H^+b\overline{t}$ , $p p\to H^+t\overline{t}$ , $p p\to H H Z$ decay modes. The presented data demonstrate the jump in the production cross section of $H^+ b \overline{t}$ and $H H Z$ production processes in the mass range of 100-200 GeV and 100-300 GeV accordingly at energy of 14 TeV.
References:
1. G. Branco et al., Physics Reports 516, 1 (2012).
2. J. Alwall et al., JHEP 07, 079 (2014).
3. P. Sanyal, Eur. Phys. J. C 79, 913 (2019).
4. K. Babu and S.Jana, JHEP 02, 193 (2019).Speaker: Dr Tetiana Obikhod (Institute for Nuclear Research NAS of Ukraine) -
216
Combined Higgs boson measurements and their interpretations in Effective Field Theories and new physics models with the ATLAS experiment
Combining measurements of many production and decay channels of the observed Higgs boson allows for the highest possible measurement precision for the properties of the Higgs boson and its interactions. These combined measurements are interpreted in various ways; specific scenarios of physics beyond the Standard Model are tested, as well as a generic extension in the framework of the Standard Model Effective Field Theory. The latest highlight results of these measurements and their interpretations performed by the ATLAS Collaboration will be discussed.
Speaker: Fabian Becherer (Albert Ludwigs Universitaet Freiburg (DE)) -
217
Searches for low- and high-mass Higgs-like resonances with the ATLAS detector
Several theories beyond the Standard Model predict the existence of new particles decaying into pairs of gauge bosons. These states generally have masses larger than that of the Higgs boson, while some theories predict resonances with masses smaller than it. The latest ATLAS results on searches for such resonances in final states with leptons and photons based on pp collision data collected at 13 TeV will be presented.
Speaker: Luis Pascual Dominguez (Tel Aviv University (IL)) -
6:10 PM
End of session
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Section 4. Relativistic nuclear physics, elementary particle physics and high-energy physics: LF,CFConvener: Evgeny Andronov (St Petersburg State University (RU))
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Study of neutral and charged pions fluctuations with ALICE experiment
Fluctuations of relative yield of neutral and charged pions are expected to be sensitive to the creation of quark-gluon matter, pion Bose-condensate or chiral phase transition, which may take place in AA, pA or even pp collisions. Quantitatively, such fluctuations can be estimated using the variable $\nu_{dyn}$ which, by its construction, reduces or completely removed most of the collisional bias, such as impact parameter fluctuations or fluctuations from the finite number of particles within the detector acceptance. In this report we will present the results of the analysis of fluctuations of charged and neutral pions using the dynamic variable $\nu_{dyn}$ in Monte-Carlo simulation of pp, pA and AA collisions at an energy of 5.02 TeV in the ALICE experiment. We will demonstrate that photons measured in the PHOS calorimeter do reproduce fluctuations of parent pions after correcting for the probability of registering one or two decay photons. We will discuss contributions of resonance decays and ways to reduce related contribution to $\nu_{dyn}$. Possible relations to recent ALICE results on charged and neutral kaon fluctuations in Pb-Pb collisions will be addressed.
Speaker: Evgeniia Nekrasova (National Research Centre Kurchatov Institute (RU)) -
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Multiplicity dependence of pion-emitting source size in p+Au and d+Au collisions at $\sqrt{s_{NN}}$~=~200 GeV in STAR experiment
Femtoscopy is a tool to measure the spatial and temporal characteristics of a system produced after a collision of two nuclei happened. Currently, it is not possible to directly measure these properties of the system, however, femtoscopy rely on a different approach to accomplish this task, it uses momentum correlations of particle pairs. Those correlations originate from quantum statistics and final state interactions of identical particles. By measuring a relative momentum distribution of two identical particles it becomes possible to extract the femtoscopic radii. The femtoscopic radii as a function of event multiplicity or a pair transverse momentum provide the information about dynamics of the system. It is also important to understand how the system size would change for different collision species.
In this work, we present the charged pion femtoscopy for p+Au and d+Au collisions at $\sqrt{s_{NN}}$~=~200~GeV taken in the STAR experiment. Emitting-source radius dependence on the event multiplicity and transverse momentum of the pion pairs will be discussed.
Speaker: Eugenia Khyzhniak -
220
Accessing the genuine three-baryon interactions via femtoscopic studies in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE
The femtoscopic studies done by the ALICE Collaboration provided results with unprecedented precision for the short-range strong interactions between different hadron pairs. The next challenge is the development of the three-particle femtoscopy which will deliver the first ever direct measurement of genuine three-body forces. Such results would be a crucial input for the low-energy QCD and neutron star studies. In particular, the momentum correlation of p–p–p triplets can provide information about genuine three-nucleon forces while the p–p–$\Lambda$ interaction is a necessary piece to understand if the production of $\Lambda$ hyperons occurs in neutron stars.
In this talk, the first study of p–p–p and p–p–$\Lambda$ correlations will be presented. The results were obtained using high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV measured by ALICE at the LHC. The measured three-body correlation functions include both three- and two-particle interactions. The cumulant method was applied to subtract lower-order contributions and infer directly on the genuine three-body forces. The two-particle contributions were estimated both experimentally by applying mixed-event technique, and mathematically by projecting known two-body correlation functions on the three-body systems. The measured p–p–p and p–p–$\Lambda$ correlation functions and the corresponding cumulants will be shown.Speaker: Laura Šerkšnytė (Technische Universitaet Muenchen (DE)) -
221
Angular correlations of particle yield ratios
Measurements of fluctuations allow one to study phase transitions and other collective phenomena in systems formed in high-energy hadronic collisions.
In this report, we will discuss properties of a recently proposed fluctuation observable, namely, the correlation coefficient between ratios of identified particle yields measured in two angular acceptance windows. With such an observable it is possible, for instance, to study the correlation between relative strangeness yield in separated rapidity intervals, which should be sensitive to the density of the fireball formed in A--A collisions. These correlations are also sensitive to various short-range effects, in particular, they are affected by spin statistics. We will show predictions from several models of pp and A--A collisions that include known effects, and these calculations will serve as baselines for the future measurements with this observable in real experimental data.Speaker: Igor Altsybeev (St Petersburg State University (RU)) -
4:40 PM
Coffee break
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222
Study of multiplicity and transverse momentum fluctuations in the Monte-Carlo model of interacting quark-gluon strings
In the search for the critical point of strongly interacting matter one of the key methods is the study of the event-by-event fluctuations of different event observables. One important aspect of this research is an accurate definition of the initial conditions event-wise. Namely, the influence of the trivial fluctuations, such as those of the system volume should be eliminated in the studied quantities or well-controlled in the experiment. From the phenomenological point of view, one can address this question in the two-stage string model of particle production, whose results can act as a baseline to estimate the non-critical background of fluctuations. In this work we develop and use Monte-Carlo model of interacting quark-gluon strings of the finite length in rapidity space to determine the influence of the string fusion on the final fluctuation measures [1]. On the other hand, the model results in comparison to the experimental data can guide us in the study of the particle production sources and their interactions.
This work is supported by the RFBR research project no. 18-02-40097.[1] Prokhorova, D.S., Kovalenko, V.N. Study of Forward-Backward Multiplicity Fluctuations and Correlations with Pseudorapidity. Phys. Part. Nuclei 51, 323–326 (2020).
Speaker: Daria Prokhorova (St Petersburg State University (RU)) -
223
Strongly intense observables as a tool for studying clusters of quark-gluon strings in relativistic hadronic interactions
The using of strongly intensive observables are considered as a way to suppress the contribution of trivial ”volume” fluctuations in experimental studies of the correlation and fluctuation phenomena [1]. In this regard, we study the properties of the strongly intensive variable $Σ$ characterizing correlations between the number of particles produced in two observation windows separated by a rapidity interval in pp interactions at LHC energies in the model with quark-gluon strings (color flux tubes) as sources [2,3].
It is shown that in the version of model with independent identical strings this variable really depends only on the individual characteristics of a string and is independent of both the mean number of strings and its fluctuation, which reflects its strongly intensive character.
In the version of the model when the string fusion processes are taken into account, and a formation of string clusters of a few different types takes place, it was found that the observable $Σ$ is proved to be equal to a weighted average of its values for different string clusters, with weight factors, depending on details of the collision - its energy and centrality [4].
The analytical calculations are supplemented by the MC simulations permitting to take into account the experimental conditions of pp collisions at LHC energies. We perform the MC simulations of string distributions in the impact
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