Gamma-Ray Spectroscopy of Neutron-Deficient Nuclides 129Nd, 131Pm and 132Pm

Sullivan, Conor
(2023) Gamma-Ray Spectroscopy of Neutron-Deficient Nuclides 129Nd, 131Pm and 132Pm. PhD thesis, University of Liverpool.

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The newly commissioned MARA recoil separator has been coupled with the efficient high-purity germanium (HPGe) JUROGAM γ-ray spectrometer and a suite of focal-plane detector systems to facilitate detailed studies of in-beam and isomeric delayed radiation emitted by various types of nuclides. Excited quantum states were populated in the highly neutron-deficient nuclides 129Nd, 131Pm and 132Pm utilising the fusion-evaporation reaction 58Ni + 78Kr > 136 Gd∗. In the study of 129Nd, three new isomeric states were observed at excitation energies of 1893, 2109 and 2284 keV, respectively. The state at 2284 keV was measured to have a half-life of 679 ± 60 ns. Excited states existing above this level were measured using the JUROGAM spectrometer and characterised within the framework of the cranked shell model. The study of 131Pm focused on detailed in-beam γ-ray measurements, resulting in extensions to the yrast band at high and low spin. To accommodate the lowest spin states, reinterpretation of the band in terms of its deformation aligned nature resulted in reassignment of the yrast band to Nilsson orbital [532]5/2−. The lowest spin state of 5/2− is then proposed to be the ground state, in agreement with theoretical studies. Finally, band extensions at high and low spin were made in the study of doubly odd 132Pm. Two low-spin isomeric states were measured, with half-lives of 187 ± 4 ns and 19.9 ± 0.5 μs. γ radiation observed to depopulate these states is proposed to feed the ground state of the this nucleus, allowing unambiguous assignment of absolute excitation energies for two of the four observed bands.

Item Type: Thesis (PhD)
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Aug 2023 15:19
Last Modified: 16 Aug 2023 15:20
DOI: 10.17638/03170270
  • Paul, Edward
  • Joss, David