Conveners
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- There are no conveners in this block
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- There are no conveners in this block
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- There are no conveners in this block
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- There are no conveners in this block
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- There are no conveners in this block
Section 1. Experimental and theoretical studies of the properties of atomic nuclei
- Sergey Yakovlev (Saint Petersburg State University)
The theoretical description of nuclear magnetic excitations within self-consistent models is hampered by the fact that the parameters of the underlying energy-density functionals (EDF) are determined without accounting for magnetic properties which leaves the EDF’s spin parameters uncertain. In a recent paper [1] we have explored low-lying M1 excitations in $^{208}$Pb within a self-consistent...
The study of nuclear giant resonances has long been a subject of extensive theoretical and experimental research. The multipole response of nuclei far from the $\beta$-stability line and the possible occurrence of exotic modes of excitation present a growing field of research. In particular, the study of the isoscalar giant monopole resonances (ISGMR) in neutron-rich nuclei is presently an...
The $\beta$-decay properties are very important for understanding the nuclear structure evolution at extreme N/Z ratios, for analysis of radioactive ion-beam experiments, and modeling of the astrophysical r-process. For this reason, the $\beta$-decay properties of r-process “waiting-point nuclei” $^{129}$Ag, $^{130}$Cd, and $^{131}$In provides valuable information, with important tests of...
The semi-microscopic particle-hole dispersive optical model (PHDOM), in which main relaxation modes of high-energy particle-hole-type nuclear excitations are together taken into account [1], has been implemented for describing various giant resonances in medium-heavy closed-shell nuclei (see, e.g., Refs. [2,3]).
A lot of experimental data concerned with giant resonances in medium-heavy...
The particle-hole (p-h) dispersive optical model (PHDOM) developed recently [1] is adopted and implemented for describing main properties of Isoscalar Giant Multipole Resonances (ISGMPR) up to L=3 in medium-heavy closed-shell nuclei. The overtones of monopole and quadrupole isoscalar giant multipole resonances are also studied. Being considered in a large excitation-energy interval, the main...
The evolution of single-particle energies $\it E_{nlj}$ of near to spherical medium and medium- heavy nuclei as they approached neutron drip line was studied within the dispersive optical model (DOM) [1]. The main attention was paid on the dependence of the diffuseness parameter $\it a_{HF}$ of the Hartree-Fock component of the potential on neutron-proton asymmetry and its influence on the...
Fully self-consistent calculation of the Odd-Even Staggering (OES) of the charge radii in the long isotopic chains is presented. The nuclei around the neutron shells at N=20, 28, 50 including non-magic ones with pairing in both neutron and proton sectors are treated in the Density Functional Theory. Well-established Fayans functional DF3-a developed in [1] is used. A comparison with its new...
The report considers the structure of high-spin (9+) isomers and the nature of rotational bands in Ho and Dy nuclei with A= 156, 158, 160.
A detailed comparative analysis of the decay of holmium isomers into dysprosium levels (Ho → Dy) for A= 156, 158, 160 (see Fig. 1.).
Fig. 1. Decay of isomer 9+ in ${}^{156}$Ho nucleus.
1. V.G.Kalinnikov et al. // Int. conference on nuclear physics...
The real observed excitation spectrum of deformed nuclei is complex and contains levels having both a rotational nature and levels arising from collective vibrations. The collective spectra of atomic nuclei with axial-symmetry quadrupole and octupole deformations are characterized by rotational bands with alternating parity.
Earlier energy sequences with alternating parity of deformed...
The self-consistent calculations with the use of functionals of both Skyrme and Fayans have been performed for the probability of E1-transitions between the first one-phonon $2^+$ and $3^-$states in Sn isotopes. Good agreement with the available experimental data has been obtained. As in our previous calculations for the quadrupole moments of the first $2^+$ [1], and $3^-$ states [2], and for...
${}^{156}$Gd-одно из изученных ядер. Причиной этого является то, что величина сечения $(n,\gamma)$ - реакции дает богатые возможности для изучения спектра излучения. Наиболее полные результаты по этому ядру представлены в работах [1,2]. В реакции $(n,\gamma)$ получены данные об уровнях ротационных полос с $K=0_{1}^{+}$ - до ${26}^{+}$, $0_{2}^{+}$ до ${14}^{+}$, $2_{1}^{+}$ до ${14}^{+}$,...
On the base of microscopic version of the IBM1 plus other bosons
of positive parity with spins from $0^+$ to $10^+$ properties of
yrast-band states in even Ce isotopes are studied. Parameters of
the boson Hamiltonian and interactions of the collective
quadrupole bosons with other bosons are calculated
microscopically. This study is a continuation of similar works on
the isotopes Xe and...
A non-adiabatic collective model that takes into account the relationship of rotational motion with longitudinal and transverse vibrations of the quadrupole type of the surface of the nucleus allows us to explain a number of patterns observed in the excitation spectra of deformable non-axial even-even nuclei.
Various well-known types of deviations of nuclear collective motion from purely...
Shape coexistence is a remarkable phenomena consisting in the presence in the same nucleus, within the narrow energy range, of two or more states which have distinct properties and can be interpreted in terms of different intrinsic shapes [1]. Recently accumulated experimental data have shown that $^{96}$Zr has coexisting spherical and deformed structures with small mixing amplitudes. The...
An extension of the self-consistent theory of finite Fermi systems [1,2] to the energy region of pygmy- and giant resonances in magic nuclei is performed with the aim to consider particle-hole (ph) and complex 1p1h⊗phonon configurations and to consistently account for the phonon coupling (PC) .
A new equation for the effective field, which determines nuclear polarizability,
has been...
The presence of an energy gap in the spectrum of single nucleon states of even-even nuclei facilitates the identification of collective excitations corresponding to a change in the surface shape and rotation of atomic nuclei. In odd atomic nuclei, the energy of single-nucleon excitations usually differs little from the energy of collective excitations; therefore, their separation is possible...
$\mathrm{Vlasnikov A.K.}, \fbox{Zippa A.I.}, \mathrm{Mikhajlov V.M.}$,
St. Petersburg State University, St. Petersburg, Russia
E-mail: a.vlasnikov@spbu.ru
If an ideal energy surface around a deformed nucleus with even $N$ and $Z$
existed and were linear and quadratic in deviations $s$ and $t$ from $N$ and $Z$
respectively $(|s| / N \ll 1,|t| / Z \ll 1)$
$\begin{aligned} E(N+s,...
Estimation of the surface tension coefficients in the even-even nuclei could be performed due to connection of surface tension and nuclear rigidity [1]. The values of rigidities are connected with the mean squared deformations of nuclei [2]. The estimation of the surface tension coefficients in the even-even nuclei were presented in [3]. The coefficients $\sigma$ show great fluctuations: from...
In recent years, several successful applications of the Artificial Neural Networks (ANNs) have emerged in nuclear physics, high-energy physics, and other fields of science. These works have already shown, that modeling of nuclear data with ANNs provides a valuable complementary approach to theory-driven models of the systematics of nuclear data (see e.g. [1] and references therein). A...
We had suggested in our previous publications (see, e.g. [1-2]) the definition of quantum chaos based on the Liouville-Arnold theorem. It states that a system featuring N degrees of freedom is regular if it has M = N linearly independent first integrals of motion in involution. First (global, isolating) integrals of motion are those that, by Noether’s theorem, are associated with the symmetry...
A (3+3)-neutrino model is used to describe the effects of sterile neutrinos in beta-decay and neutrinoless double beta-decay of nuclei. This model was detailed in [1] and includes three active neutrinos να (α = e, , ) and three new sterile neutrinos: a sterile neutrino νs, a hidden neutrino νh and a dark neutrino νd. The 66 mixing matrix Umix is used in the model. The values of mixing...
Stable isotope selenium-82 is a perspective object for double beta decay investigations and searches for neutrinoless transition. It is used as a 2-source in large-scale projects - NEMO-3, SuperNEMO, CUPID-0. In the recent experimental works [1,2] two-neutrino channel for 82Se was examined in order to determine nuclear mechanism of 22-decay. The question is whether contribution of the...
Mechanism of simultaneous non-sequential four-neutron (4$n$) emission (or "true" 4$n$-decay) has been considered in phenomenological five-body approach.
This approach is analogous to the model of the direct decay to the continuum often applied to 2$n$- and 2$p$-decays. It is demonstrated that 4$n$-decay fragments should have specific energy and angular correlations reflecting strong...
Successful applications of the total absorption $\gamma$-spectroscopy $(TAGS)$ for the $\beta$-decay strength function $S_{\beta}(\textit{E})$ resonance structure study, methods of $TAGS$ spectra interpretation, and results of analysis of $S_{\beta}(\textit{E})$ structure for the Gamow-Teller $(GT)$ $ \beta^{+}/EC$ and $\beta^{-}$ -decays were summarized in [1,2]. Development of...
The $\beta$-decay strength function $S_{\beta}(\textit{E})$ governs [1,2] the nuclear energy $\textit{E}$ distribution of elementary charge-exchange excitations and their combinations like proton particle $({\pi}p)$-neutron hole $({\nu}h)$ coupled into a spin-parity $I^{\pi}$: $[{\pi}p \otimes {\nu}h]I^{\pi}$ and neutron particle $({\nu}p)$-proton hole $({\pi}h)$ coupled into a spin-parity...
The $\beta$-transition probability is proportional to the product of the lepton part described by the Fermi function $f( \textit{Q}_{\beta} - E)$ and the nucleon part described by the $\beta$-decay strength function $S_{\beta}(\textit{E})$, where $E$ is the excitation energy in daughter nuclei and $ \textit{Q}_{\beta}$ is the total energy of $\beta$-decay.
The previously dominant statistical...
The SIDDHARTA-2 and AMADEUS collaborations aim to provide experimental information on the low-energy strong interaction between antikaons and nucleons. The investigation of the antikaons dynamics in nuclear medium is fundamental for understanding the non-perturbative QCD in the strangeness sector, with implications going from the domain of nuclear physics to astrophysics. The DA$\Phi$NE...
Hypernuclei provide an excellent opportunity to investigate the properties of baryon-baryon interaction. Exotic systems with a neutron or proton excess are of particular interest. The response of weakly bound nuclear states to hyperon addition is determined by the core polarization by the hyperon [1]. Due to the glue-like role of the Λ-hyperon, there is a chance to stabilize loosely bound...
During the decay of Yb and Tm, Er with A = 157, the structure and isomerism of daughter isotopes levels were studied.
An investigation of ${}^{157}$Er decay made it possible to establish a scheme of ${}^{157}$Ho excited states in the energy range up to 3 MeV.
The spectra of gamma rays, electrons, and gamma-gamma coincidence were studied.
The obtained experimental results were compared...
The study of nuclear matter is one of the most interesting branches of nuclear physics from a theoretical and experimental point of view. Especially it goes quite capacious when the internal structure of studying nuclei is extraordinary. As an example can be nuclei in follow: ${}^{6}$He and ${}^{6}$Li, which are unstable and have a Borromean structure; ${}^{9}$Be having also Borromean...
Recently a strong disagreement between the theoretical prediction [1] of the specific difference of hyperfine splittings in H-like and Li-like $^{209}$Bi ions and the experiment was found [1]. This problem was called the “hyperfine puzzle”. We have shown [3] that the reason of the discrepancy was caused by the inaccurate "standard" value of the magnetic moment of the $^{209}$Bi nucleus, which...
Search for spatial parity and time-invariance violation is one of the most topical fields of particle physics. Observation of P,T-invariance violation at atomic and molecular physics may lead to some new restrictions for Standard Model extensions and even be indirect evidence of unknown particles existence. So, precise theoretical and experimental study of molecular electronic structure is...
Structure of nuclei near Z=50 proton magic shell closure and neutron number near Z=64 subshell closure are found to exhibit the single-particle structure that coexist with the collective structure and therefore, gives the possibility to investigate both the structures within the single nuclear system [1-3]. The collective band structures have been systematically observed in both odd-odd and...
Beside of the general interest to structure of the light exotic nuclei 10Li attracts attention of theoreticians as well as experimentalists because this nucleus is a binary subsystem of famous halo-nuclei 11Li. Last time many experiments were devoted to study the structure of low energy spectrum of 10Li but to the moment the status is far from consensus, even the spin-parity of the ground...
An overview of experimental results on the level structure of heavy helium isotope 8He, obtained in the reactions of the stopped pion absorption by light nuclei, is presented. Excited states of the 8He were observed in several reaction channels on the 9Be, 10,11B and 12C nuclei: 9Be(pi-,p)8He, 10B(pi-,pp)8He, 11B(pi-,pd)8He, 11B(pi-,3He)8He, 12C(pi-,p3He)6He, 14C(pi-,d4He)8He and...
The unbound heavy helium isotope $^{9}$He was discovered in pion double charge exchange reaction $^{9}$Be($\pi^{-}$,$\pi^{+}$)$^{9}$He at E$_{\pi}$ = 194 MeV [1]. Despite a significant number of experiments performed to date, the problem of the level structure of $^{9}$He remains open [2, 3]. In particular, the energy and quantum numbers of the ground state are undefined. The studied range of...
Clusters of gas atoms are a large class of molecules interacting via van der Waals type potentials. Some weakly bound clusters show universal characteristics and scale invariants related to the famous Efimov effect [1], which was experimentally confirmed in an ultracold gas of the Cs atoms [2]. The helium trimer system has been long considered as an ideal candidate for observing Efimov states....
One of the fundamental physical limits on the speed of the time evolution of a quantum state is known in the form of the celebrated Mandelstam-Tamm inequality. This inequality gives an answer to the question on how fast can an isolated quantum system evolve from its initial state to an orthogonal one. Extensions of the Mandelstam-Tamm inequality give optimal speed bounds for the evolution...
Calculation of vibrational-rotational bound states and metastable states of a diatomic beryllium molecule important for laser spectroscopy [1] are presented. The solution to the problem is performed using the potential curve given in [2,3] and the authors' software package that implement the iteration Newton method and the high-accuracy finite element method [4]. The efficiency of the...
Three-atomic molecules at ultralow energies are of a great interest in both experiment and theory.
The ability to control the scattering length in ultracold gases make these systems ideal candidates for experimental study of Efimov
physics [1]. After the first successful observation of Efimov states in an ultracold Cesium gas [2],
a lot of the experimental evidence for the Efimov states...
The long-lived interest to weakly-bound triatomic systems is stimulated by their connection with Efimov physics [1]. While the most studied system is the Helium trimer [2], there is a variety of other systems [3,4] like helium-alkali triatomic molecules under investigation. Although their bound states with zero total orbital momentum lie very close to the breakup threshold, some of those...
The recent results [1,2] of the dibaryon model for nucleon-nucleon (NN) interaction are presented. The model is based on a mechanism with the intermediate six-quark (dibaryon) state formation. Thus, the total Hamiltonian of the system has a two-channel matrix form where the external channel corresponds to the ordinary relative motion of two nucleons and the internal channel takes into account...
Systems of particles with a low binding energy and a wave function that is widely distributed in space are considered in this work. The study of these systems is not an easy task and requires different approaches, solution methods and additional computational recourses. Extensive studies of weakly bound systems have been conducted in recent times [1,2,3].
The goal of the work is the...
SCATTERING PROCESSES IN FEW-BODY SYSTEMS WITH NON-ZERO ANGULAR MOMENTUM
Yarevsky E.A. and Yakovlev S.L.
Department of Computational Physics, St Petersburg State University, St Petersburg, Russia
E-mail: e.yarevsky@spbu.ru
Scattering problems for few-body systems are of great importance for many physical processes. The complicated boundary conditions at large distances, especially for...
The asymptotic form of the wave function of a few-particle system in the continuum is described. The contribution of the rescattering processes in the leading terms of the asymptotic behavior of the wave function is analyzed. The hyperradial asymptotic behavior of the wave function is found after averaging over the hyperspherical angular variable. The perspective of applications to the...
