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Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Muir, D.*; Prchniak, L.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; et al.
Physical Review C, 110(2), p.024318_1 - 024318_16, 2024/08
被引用回数:0 パーセンタイル:0.00(Physics, Nuclear)In the selenium isotopes various shape phenomena are present, in particular the emergence of a dominant oblate deformation in the most neutron-deficient isotopes has been observed. The scenario of shape coexisting oblate and prolate bands has been proposed across the isotopic chain, with the crossing point of such bands being located near Se, where no coexistence has yet been identified. To determine the presence or absence of any low-lying state in Se, confirm the level structure, and interpret the nuclear deformation with theoretical models. A combined internal conversion electron and -ray spectroscopy study was undertaken with the SPICE and TIGRESS spectrometers at the TRIUMF-ISAC-II facility. Nuclear models were provided by the Generalised Triaxial Rotor Model (GTRM) and the collective Generalised Bohr Hamiltonian (GBH). Despite a comprehensive search, no evidence was found for the existence of a state below 2 MeV in Se. Significant discrepancies to the previously established positive parity level scheme were found. GBH calculations using UNEDF1 mass parameters were found to reproduce the revised low-lying level structure well. Se does not have a well defined axial shape. The 2 state at 1601 keV resembles a quasi- excitation rather than a member of a shape coexisting band; the presence of such a band is all but ruled out.
Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.
Physical Review C, 106(1), p.014312_1 - 014312_9, 2022/07
被引用回数:5 パーセンタイル:70.77(Physics, Nuclear)The selenium isotopes lie at the heart of a tumultuous region of the nuclear chart where shape coexistence effects grapple with neutron-proton pairing correlations, triaxiality, and the impending proton dripline. In this work a study of Se by internal conversion electron and -ray spectroscopy was undertaken with the SPICE and TIGRESS arrays. New measurements of the branching ratio and lifetime of the state were performed yielding a determination of milliunits. Two state mixing calculations were performed that highlighted the importance of interpretation of such strength values in the context of shape-coexistence.
Gillespie, S. A.*; Stott, A.*; Andreyev, A. N.; 他30名*
Physical Review C, 103(4), p.044307_1 - 044307_9, 2021/04
被引用回数:1 パーセンタイル:15.62(Physics, Nuclear)Proton-rich Au isotopes are an excellent laboratory to study shape coexistence and isomerism at low excitation energies. In this work, two new isomeric states were found in the odd-odd nuclide Au in an experiment at RITU in JYFL, Jyvaskyla. These two isomers significantly extend the current knowledge of this nucleus and pave the way to future in beam studies where they will be used to tag new gamma rays. Possible spin assignments for the new isomeric states are proposed. Finally, the new data will help clarify the poorly known -decay scheme of two long-lived states in the Tl to Au decay chain.
Gillespie, S. A.*; Andreyev, A. N.; Al Monthery, M.*; Barton, C. J.*; Antalic, S.*; Auranen, K.*; Badran, H.*; Cox, D.*; Cubiss, J. G.*; O'Donnell, D.*; et al.
Physical Review C, 99(6), p.064310_1 - 064310_6, 2019/06
被引用回数:3 パーセンタイル:30.18(Physics, Nuclear)An experiment has been performed to study excited states in the neutron-deficient nucleus Ir via the use of the JUROGAM II high-purity germanium detector array and the RITU gas-filled separator at JYFL, Jyvskyl. By using isomer tagging, an isomeric state with a half-life of 6.58(15) s has been observed in Ir for the first time. It has been established that the isomer decays via a 45.2 () - 26.1 () keV cascade to new states below the previously reported ground state in Ir with . We now reassign this state to the isomeric state discovered in this study.
West, J. M.*; 青木 和弘; Baker, S. J.*; Bateman, K.*; Coombs, P.*; Gillespie, M. R.*; Henney, P. J.*; Reeder, S.*; Milodowski, A. E.*; 吉田 英一
JNC TJ7400 99-002, 117 Pages, 1997/01
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Smallcombe, J.; Garnsworthy, A. B.*; Korten, W.*; Singh, P.*; Ali, F. A.*; Andreoiu, C.*; Ansari, S.*; Ball, G. C.*; Barton, C. J.*; Bhattacharjee, S. S.*; et al.
no journal, ,
The phenomenon of shape coexistence is prevalent in the Z34 region, with isotopes of neutron-deficient even Ge, Se and Kr each exhibiting the characteristic low-lying coexisting 0+ bands which display quadrupole deformation different to that of the ground states. In the selenium isotopes, Se seem to show a prolate ground structure with shape coexisting oblate excitation, while in Se the oblate structure appears to have become the ground state. The exact nature of the low-lying structure Se and any shape coexistence remains uncertain. Combining the Spectrometer for Internal Conversion Electrons (SPICE) with the TIGRESS HPGe Array, a full electron and gamma-ray experimental study of Se, Se was undertaken at the TRIUMF ISAC-II facility to unveil the low-lying structure of these nuclei. Details of the device and experiment will be presented, alongside the experimental results and possible structural interpretations for both isotopes.