Despite the atomic nuclei are quantum many-body systems made of interacting protons and neutrons, their spectra can be in many cases described by simple geometrical models. The best framework to explain microscopically such a collective behavior is the self-consistent mean-field approach based on energy density functionals like Skyrme, Gogny or Relativistic Mean Field. These methods have been...
ISOLTRAP [1] mass measurements of neutron rich copper isotopes are presented. $^{79}$Cu could be addressed by the first time using a Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF MS) [2]. With only one proton above the $Z$ = 28 core, the binding energies of the copper isotopes are sensitive to the evolution of nuclear shell structure close to the doubly-magic $^{78}$Ni isotope....
Shape staggering, shape coexistence and beta-delayed fission in bismuth isotopes studied by in-source laser spectroscopy (IS608)
A. Barzakh
*Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, 188300 Gatchina, Russia
On behalf of Leuven-Gatchina-ISOLDE-Mainz-Manchester-York and Windmill-ISOLTRAP-RILIS...
The idea that “new-is-small” reflects a paradigm moving industries and research. New materials, new applications, new technologies, - but what do we need to make the “new”, understandable, applicable and reliable? Clearly, as things go smaller and smaller, it is more difficult to probe at the appropriate scale without influencing the subject of interest. Ideally, one needs tip-less...
Most ferroelectrics are oxides of a number of different crystal classes. Their polar ordering typically arises as soft phonon process with one or more of the ionic entities shifting within the unit cells. This lowers the symmetry into polar symmetry groups. If nuclear probes substitute the inherent ions in the structure, their local environment more or less reflects the crystal symmetry. One...
Mg-doped p-type GaN is nowadays a core component of many optoelectronic devices which we find in our homes, e.g. LEDs for solid state white lighting or blue lasers. Yet there are some basic properties related to p-type doping of GaN that are still poorly understood and also limit the performance of devices. One such major problem is an inherent doping limit: once the Mg concentration in GaN...
The rock-forming alkali feldspars belong to the most abundant minerals in the Earth’s
crust and are formed as a solid solution between the sodium (NaAlSi$_3$O$_8$, albite) and
potassium (KAlSi$_{3}$O$_8$, orthoclase) end-member compositions. Well-founded knowledge
of self-diffusion data in alkali feldspar is a prerequisite for interpreting existing
interdiffusion data that, in turn control...
Rare-earth orthochromites of the formula RCrO$_3$ R=Dy, Pr, Ho, Yb, Er, Y, Lu, Sm are currently at the center of great controversy regarding ferroelectricity. While dielectric constant anomalies near $400-500$ K in the heavier rare-earth chromites were associated with non-centrosymmetry, others claim that the polarization observed in these systems is due to the combined effect of the electric...
So far, double charge exchange reactions have been less explored than single charge exchange reactions. We have revisited double charge exchange reactions and found their discovery potentials in two cases: one is production of a tetraneutron state and the other is a search for double Gamow-Teller Giant resonances. In the both cases, new techniques which exploit properties of exotic nuclei have...
The Facility for Rare Isotope Beams (FRIB) being built at Michigan State University (MSU), is based on a 400 kW, 200 MeV/u heavy ion driver linac. Once completed, FRIB will offer world‐unique opportunities for rare isotope science. It will provide a wide variety of high‐quality beams of unstable isotopes at unprecedented intensities, opening exciting research perspectives with fast, stopped,...
The NUSTAR Collaboration will perform experiments with relativistic exotic nuclei at GSI and FAIR. Presently, several new FAIR detector systems are under construction for high-resolution spectrometer experiments, decay spectroscopy, reaction studies with internal or external targets, and for experiments with stopped beams. Due to the delayed start of the FAIR project, several prototypes or...
CARIBU provides neutron-rich low-energy and reaccelerated beams to the ATLAS user’s community. It is unique in that it relies on spontaneous fission from a 252Cf source to produce the neutron-rich isotopes that are cooled and extracted as a low-energy beam using a large gas catcher and guiding radio-frequency structures. These beams are accelerated to 50 kV, purified by a compact...
The lightest nuclei present physics problems where progress is only made incrementally and slowly. New instrumentation is then essential for further advances. We present here two examples taken from ISOLDE runs in 2016.
The first problem is motivated in the astrophysically very important 12C(a,g)16O reaction. The cross section of this reaction at energies relevant to stellar helium burning is...
One of the most important unresolved problems in Nuclear Astrophysics is the so-called “Cosmological Lithium problem” (CLiP). It refers to the large discrepancy (factor 3-5) between the abundance of primordial 7Li predicted by the standard theory of Big Bang Nucleosynthesis (BBN) and the value inferred from the so-called ”Spite plateau” in halo stars.
In the framework of Standard Model, a...
183Hg -> 183Au decay was studied using the TATRA system. Conversion electrons were detected with the LN2 cooled windowless Si(Li) detector. The tape system was operated at 8E-8 mbar, therefore no deposition of mist on the surface of cold detector was observed during the run. The FWHM of 1.3 keV for conversion electrons above 100 keV was achieved, which is almost comparable with previous...
The propensity to adopt different shapes to minimize energy is a remarkable property of atomic nuclei. Nuclei around the $Z = 82$ shell closure exhibit a wide variety of these shapes. Low-lying excited states with different shape configurations to the ground state lead to shape-coexistence below the $N = 126$ shell closure. Additionally, octupole-deformed nuclei are found above the $N = 126$...
The work presented here pertains measuring the sign and magnitude of the spectroscopic quadrupole moment for the first excited 2+ state, Qs(2+), in 36Ar. This was done through a Coulomb excitation measurement using the reorientation effect at safe energies. The measurement was performed using a distance between nuclear surfaces of at least 6.5 fm as proposed by Spear in 1981 for light nuclei...
The VITO beamline (Versatile Ion-polarized Techniques Online) is the result of a recent initiative to combine several hyperfine interaction techniques requiring both spin-polarized and unpolarized nuclei for experiments relevant to material and life sciences, as well as nuclear physics and fundamental interactions studies. The first online experiment at VITO was performed at the end of 2014...
This poster will present the development of a new radio-frequency cooler buncher (RFCB) design for the collinear resonance ionisation spectroscopy (CRIS) experiment. A RFCB at CRIS would provide numerous benefits including the replication of online conditions during offline testing and would act as a beam energy reset; allowing CRIS to remain in a fixed setup. Due to spatial restrictions, a...
Electron emission channeling accurately measures the lattice location of radioactive impurities in single crystals by looking at the anisotropic emission of decay electrons (beta particles or conversion electrons) in the vicinity of major crystallographic directions. Lately, the search for the advantages that modern position-sensitive detectors (PSDs) can bring motivated several emission...
$^{208}$Pb is the heaviest stable doubly-magic nucleus and has been studied in great detail. Its first excited state occurs at 2.6 MeV and corresponds to an octupole vibration, resulting from the collective behaviour of a number of $E3$ ($\Delta l = \Delta j = 3$) particle excitations across the closed shell. This octupole transition has been observed in several other nuclei around...
The region of the chart of nuclei close to the doubly-magic nucleus 132Sn has been the object of
enormous interest in both experimental and theoretical investigations for the last several years. This
activity is well-motivated by the fact that nuclei with large neutron excess are an ideal playground
to verify the reliability of shell model predictions for nuclei far from stability. Crossing...
Gallium nitride (GaN) and related compounds represent a unique class of semiconductors with extraordinary properties related to their crystal structure, optical-, and electrical response.
Their exceptional properties have turned them into building-blocks for a wide range of state-of-the-art applications in optoelectronic and high-frequency devices including light emitting diodes, laser...
Highly porous nanograined materials have been developed throughout the last 10 years at ISOLDE-CERN, to deliver high and stable intensities of radioactive ion beams. The small grains provide short diffusion distances to the produced isotopes, while, after evaporation from the grain surface, the high porosity is beneficial for the isotope to escape the material envelope.
Embossed and rolled...
Laser spectroscopy enables a reliable determination of nuclear ground-state spins, moments and mean-square charge radii. Optical isotope shifts and hyperfine structures were measured for Ni ($\textit{Z}$ = 28) isotopes on the atomic transition $3d^94s^1$ $^3D_3 \rightarrow $ $3d^94p^1$ $^3P_2$ at 353.45nm. By using the COLLAPS setup at CERN-ISOLDE, measurements of $^{58-68,70}$Ni were made in...
Time Differential Perturbed Angular Correlation of γ-rays (TDPAC) experiments were performed in late 2014 for the first time using the decay cascade from 68mCu (6-, 721 keV, 3.75 min) at the VITO beam line at ISOLDE-CERN. Due to the relatively short half-life the TDPAC measurements were performed online at an improvised provisional experimental setup, where selected samples were chosen such...
Highly selective and efficient laser ion sources are of fundamental importance to study atomic and nuclear properties along the nuclear chart. Upgrading the well-established, highly element-selective laser resonance ionization technique with additional suppression of isobaric contaminations immediately at the exit of the hot ion source cavity led to the development of the Laser Ion Source and...
Nuclear reactions involving the production and destruction of 7Be is very much relevant in search for a solution to the cosmological lithium problem. In the experiment IS 554, we plan to measure with better accuracy the destruction of 7Be through resonance excitation of 7Be (d,p) 8Be*. This is required before one can invoke solutions beyond nuclear physics, particularly the newly conjectured...
In my talk, I will present first preliminary results of the 2016 campaign at HIE-ISOLDE with the MINIBALL and C-REX arrays and give an outlook for the planned experiments in the next years.
Neutron deficient $^{110}$Sn has been studied in safe Coulomb excitation using the MINIBALL array at HIE-ISOLDE.
$^{110}$Sn was post accelerated to 4.5 MeV/u and excited against a $^{206}$Pb target.
Previous measurements performed at REX-ISOLDE measured the reduced transition probability, B(E2), of $^{106,108,110}$Sn to the first excited 2$^+$ state with a precision of ~10-20\%.
These...
Few nuclei have attracted as much attention as $^{78}$Ni in the last decades, but unfortunately it remains out of reach of current generation ISOL facilities. For this reason, with only two protons above nickel, and the increasing occupation of neutrons in the $1g_{9/2}$ orbital, neutron-rich Zn isotopes are ideally suited to study the evolution of the proton shell gap, Z = 28, and the...
The availability of radioactive beams at energies (~10 MeV per nucleon) and intensities (>10^4 ions per second) conducive to transfer reaction measurements at HIE-ISOLDE will open up new opportunities for the study of the single-particle properties of nuclei in exotic systems. A new spectrometer, the ISOL Solenoidal Spectrometer (ISS), is being commissioned to exploit the available radioactive...
Negatively charged ions are mainly stabilized through the electron correlation effect. A measure of their stability is their binding energy which is termed the electron affinity (EA). This fundamental quantity is, due to the almost general lack of bound excited states, the only atomic property that can be determined with high accuracy for negative ions. Together with the ionization potential...
For the past 60 years, the ISOLDE facility has delivered beams of high intensity and quality to the community worldwide. To keep a leading role in the development of ISOL beam production, beams and target developments are constantly done to reach new types of isotopes, yet unmet intensities or purity grades. These developments are done in various fields such as material science, ion source and...
Among the different types of target, use of the neutron converter type has resulted in increased dynamic electrical load seen by the actual 60 kV extraction voltage modulator, with the consequence that the recovery time of the target voltage to the precision of 0.001% is delayed, which in turn reduce the possibilities for the detection of exotic isotopes with extremely short half-lives. This...
Highlights of the 2016 on-line period will be presented, together with the latest results from the continuous RILIS R&D undertaken at ISOLDE. Expanding RILIS capabilities increase the possibility for customized (experiment specific) operation.
The RILIS was requested for >75% of ISOLDE experiments in 2016. There have been a number highlights from the RILIS perspective. On the experimental...
After the first successful physics run with radioactive ion beams at HIE ISOLDE, in October 2015, the staged deployment of the linac continued in 2016 by adding a second cryomodule and by refurbishing the first one. During the physics run with one cryomodule, the second cryomodule was being assembled. The refurbishment of the first cryomodule was made necessary to overcome limits imposed by...
The High Intensity and Energy ISOLDE project (HIE-ISOLDE) is a major upgrade of the ISOLDE facility at CERN. The energy range of the post-accelerator will be extended from 2.85 MeV/u to 9.3 MeV/u for beams with A/q = 4.5 (and to 14.3 MeV/u for A/q = 2.5) once all the cryomodules of the superconducting accelerator are in place. The project has been divided into different phases, the first of...
A new design of the Quarter Wave Resonator (QWR) for Cryomodule (CM) 4 will be presented.
Since the performance of the recent QWRs produced seems limited by the welding at the highest radio-frequency (RF) magnetic field, intensive efforts have been made to design a seamless QWR without welding process. A beam port was removed for machining the whole shape of the cavity from a one single bulk...
The REX-ISOLDE post-accelerator comprises 7 RF cavities that are powered by their respective RF systems. Their purpose is the acceleration of radioactive ion beams of a wide spectrum of ion species from 5keV/u to up to 3MeV/u. This talk will provide a short introduction to the RF systems of this accelerator, and it will then focus on their operation and current limitations.
We discuss a current status of the shell-model calculations with charge-dependent Hamiltonians. In an empirical approach, such a Hamiltonian includes a two-body Coulomb interaction and effective charge-dependent forces of nuclear origin, resulting in five or six additional parameters for an sd or pf shell, respectively.The accuracy of the method is demonstrated on the description of...
A summary of the 2016 experimental campaign at the ISOLDE Decay Station will be presented alongside the preliminary results. The presentation will also include highlights of the already published results concerning the fast-timing study of 129Sn, the beta-delayed proton emission measurement of 20Mg and the 31Ar multi-particle decay experiment.
Exotic neutron-rich nuclei around N=40 exhibit rapid structural changes with proton and neutron number. While 68Ni40 shows signatures of a doubly magic nucleus, excitation energies and transition strengths suggest a rapid development of collectivity in the ground state of neutron-rich 26Fe and 24Cr isotopes towards N=40. Accurate masses in this...
The Collinear Resonance Ionization Spectroscopy experiment (CRIS) at ISOLDE combines the high sensitivity of resonance ionization spectroscopy with the high resolution offered by collinear laser spectroscopy. The first experiments at CRIS demonstrated the ability to reach exotic isotopes, normally out of reach for collinear laser spectroscopy methods based on photon detection, with an...
Bunched-beam collinear laser spectroscopy was added to the extensive list of techniques used to study the Bi isotopic chain at ISOLDE. The atomic hyperfine splitting in the transition previously employed for in-source laser spectroscopy was not fully resolved in the in-source measurements. As Bi is a well-known example of the Bohr-Weisskopf effect or “Hyperfine anomaly”, it became apparent...
In the beta decay of exotic nuclei, far from stability, the daughter nuclei might be formed in an excited state, which is unstable against particle emission. This phenomenon is called β-delayed particle emission and is due to a high Q-value and low separation energy for particle emission. The decay of the proton drip-line nucleus $^{31}$Ar is one of the most exotic β-delayed multi-particle...
Introduction
Interest in the element terbium (Tb) for medical application has grown recently [1]. Four Tb isotopes have been identified with the potential to provide unique theranostic treatment strategies which combine cancer therapy with diagnostic imaging. The isotopes $^{155}$Tb and $^{152}$Tb can provide SPECT and PET imaging respectively [2], whilst $^{161}$Tb can be used for beta−...
The study of porous nanoparticles as drug carriers is a growing field in cancer-therapy
research. The porous properties of the particle enable the anti-cancer drugs to be loaded
inside the particles and the surface of the particle can be modified with targeting moieties. The nanoparticles are then injected into the bloodstream and with the penetrative capabilities of the nanoparticle the...
The VITO (Versatile Ion-polarized Techniques Online) is a new beamline at ISOLDE that was initiated in 2014 due to the high demand for polarized beams in different areas of research, such as atomic physics, nuclear physics, solid state physics and biophysics [1].
In 2016, intensive designing and off line testing of the laser polarization β-asymmetry setup took place. The first on-line tests...
C. O. Amorim (1), J. N. Gonçalves (1), D. S. Tavares (2), C. B. Lopes (2), A. S. Fenta (1,3), T. Trindade (2), E. Pereira (2), J. G. Correia (4), V. S. Amaral (1)
- Physics Department and CICECO, University of Aveiro, 3810-193 Aveiro, Portugal
- Department of Chemistry, CICECO and CESAM, Aveiro Institute of Nanotechnology, University of Aveiro, 3810-193 Aveiro, Portugal
- KU Leuven,...
SiC is a wide band-gap semiconductor with several decades of material research and device development in high-power electronics with commercially successful applications. Transition metals (TM) impurities are invariably found in bulk samples of SiC due to the production processes normally employed. It is known that those impurities, either in their isolated form or when in complexes with other...
Graphene is a two-dimensional (2D) atomic crystal which consists of a single graphite layer with strong covalent bonds between carbon arranged in a hexagonal lattice. Since it was isolated by André Geim and Konstantin Novoselov in 2004, graphene has become a remarkable subject of research, exhibiting novel phenomena that extend to virtually every domain of material’s science and applications...
As the only ISOL facility worldwide, ISAC-TRIUMF is routinely operating targets under particle irradiation in the high-power regime in excess of 10 kW. TRIUMF’s current flagship project ARIEL, Advanced Rare IsotopE Laboratory, will add three new target stations providing isotopes to the existing experimental stations in ISAC, to a dedicated collection station as well as for chemical...
An overview of the current science program for the ISAC facility at TRIUMF is given, and the status
and plans for the upcoming ARIEL facility will be presented.
Beta decay is formidable laboratory for the study of weak interaction. These decays give today the most precise value of the Vud quark-mixing matrix and competitive limits on physics beyond the standard model like scalar or tensor currents. In my talk, I will cover the present status of 0+-0+ and mirror beta decays to determine the Vud matrix element and describe present and future activities...
The charge radius of a nucleus is one of its defining parameters and of inherent importance for the understanding and the calculation of its interactions. For elements heavier than Z=83, where no stable isotopes exist, only few nuclear charge radii have been measured. These measurements are of paramount importance to complement the measurements of relative difference in mean-square radii along...
