.
The multi-particle-plus-triaxial-rotor (MPR) model calculations were performed for several nuclei in the 100, 130 and 190 mass regions. Multiple chiral systems associated with many-particle nucleon ...configurations were found, but they may not necessarily form pairs of near-degenerate bands in an obvious way. Excited chiral systems may exhibit better near-degeneracy than the yrast one. Projections of the angular momenta along the nuclear axes were examined to study the nature of the chiral bands.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The nuclear level density (NLD) and γ-ray strength function (γSF) of 63Ni have been investigated using the Oslo method. The extracted NLD is compared with previous measurements using particle ...evaporation and those found from neutron resonance spacing. The γSF was found to feature a strong low-energy enhancement that could be explained as M1 strength based on large-scale shell model calculations. Comparison of γSFs measured with the Oslo method for various Ni isotopes reveals systematic changes to the strength below 5MeV with increasing mass.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The conditions for reaching degeneracy in chiral partner bands built on two-quasiparticle configurations are examined using the two-quasiparticle-plus-triaxial-rotor model. It is shown that in order ...for degeneracy to occur it is not sufficient to have an aplanar orientation of the total angular momentum, but the angular momenta of the two valence particles need to be completely aligned along the short and long nuclear axes. Such perfect alignment seems impossible to reach with realistic parameters within this model. These results suggest that two-quasiparticle chiral bands may be formed in suitable nuclei, but perfect degeneracy between the partner bands is unlikely to be found.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Two nearly degenerate positive-parity bands with the πg9/22⊗νg9/2−1 configuration and three nearly degenerate negative-parity bands with the πg9/2(p3/2,f5/2)⊗νg9/2−1 configuration have been ...identified in 81Kr. They are interpreted as chiral doublet bands and pseudospin-chiral triplet bands, which is supported by the constrained covariant density functional theory and the multiparticle plus rotor model calculations. The present work reports two new chiral configurations πg9/22⊗νg9/2−1 and πg9/2(p3/2,f5/2)⊗νg9/2−1, and the first example of pseudospin-chiral triplet bands involving the π(p3/2,f5/2) pseudospin doublet.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Three ΔI=1 bands with the πg_{9/2}⊗νg_{9/2} configuration have been identified in _{35}^{74}Br_{39}. Angular distribution, linear polarization, and lifetime measurements were performed to determine ...the multipolarity, type, mixing ratio, and absolute transition probability of the transitions. By comparing these experimental observations with the corresponding fingerprints and the quantum particle rotor model calculations, the second and third lowest bands are, respectively, suggested as the chiral partner and one-phonon wobbling excitation built on the yrast band. The evidence indicates the first chiral wobbler in nuclei.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Abstract
The Low Energy Radioactive Ion Beam (LERIB) facility 1 will be used to produce low-energy radioactive-ion beams (RIBs) with energies up to 60 keV. Radioactive reaction products will be ...created by a 66 MeV proton-beam impinging on a target made of carbide disks, such as SiC 2. These reaction products will then be ionized in a target-ion-source (TIS) and extracted as beam. The TIS design allows three ion-sources: a surface ion-source 3, a forced electron-beam induced arc-discharge (FEBIAD) ion-source 4, and a resonance-ionization laser ion-source, or RILIS. The surface-ionization source was commissioned with stable beams in October 2021. The production of ions from Group-1 elements was accomplished with beams of
39
K
+
,
41
K
+
and
23
Na
+
where currents were measured in the
μ
A range. This source may be advantageous for producing stable pilot-beams for future radioactive-beam experiments. The FEBIAD is still in development at present.
Gamma-ray line production cross sections from nuclear reactions induced by 30 - 200 MeV protons on natC and Mylar targets have been measured at the SSC facility of iThemba LABS. Results for the 4.439 ...and 6.129 MeV prominent lines of 12C and 16O of astrophysical concern are reported and discussed.
We report γ-ray spectra for the line observed at Eγ = 4.44 MeV in our previous experiments at iThemba LABS’ SSC facility using 30 - 200 MeV proton beams to irradiate a natC target. It is actually a ...complex composed of several lines of interest broadened by Doppler effect. In addition to the dominant 4.439 MeV line of 12C, two other lines at Eγ = 4.319 and 4.445 MeV assigned to 11C and 11B, respectively, are significant components of this complex. The analysis of its line shapes based on nuclear reaction models is the main topic of this contribution.
Reaching new depths in nuclear structure investigations requires new experimental equipment and new techniques of data analysis. The modern γ-ray spectrometers, like AGATA and GRETINA are now built ...of new-generation segmented germanium detectors. These most advanced detectors are able to reconstruct the trajectory of a γ-ray inside the detector. These are powerful detectors, but they need careful characterization, since their output signals are more complex. For instance for each γ-ray interaction that occurs in a segment of such a detector additional output signals (called proportional crosstalk), falsely appearing as an independent (often negative) energy depositions, are registered on the non-interacting segments. A failure to implement crosstalk correction results in incorrectly measured energies on the segments for two- and higher-fold events. It affects all experiments which rely on the recorded segment energies. Furthermore incorrectly recorded energies on the segments cause a failure to reconstruct the γ-ray trajectories using Compton scattering analysis. The proportional crosstalk for the iThemba LABS segmented clover was measured and a crosstalk correction was successfully implemented. The measured crosstalk-corrected energies show good agreement with the true γ-ray energies independent on the number of hit segments and an improved energy resolution for the segment sum energy was obtained.