Nuclear structure studies of 159Er up to high spin

Mohammed Mustafa, Mohammed
Nuclear structure studies of 159Er up to high spin. Doctor of Philosophy thesis, University of Liverpool.

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In the current work a detailed spectroscopic investigations of the gamma-decays from the excited states of the rare-earth nucleus 159Er has been performed to study the structural properties up to possible ultrahigh spins. The nucleus of 159Er had been populated by the reaction 116Cd(48Ca,5n ) at beam energy of 215-MeV in an experiment at Argonne National Laboratory using the Gammashphere array. Following a hypercube analysis of the collected data, new rotational bands were observed and the previously reported bands were extended up to possible spin through observation of new gamma-ray transitions in coincidence with the existing sequences. Possible angular intensity-ratio, B(M1)/B(E2)-ratios, measurements have been performed to confirm the nature of previously observed transitions and to assign multipolarites of the new ones. The band structures are discussed within the framework of cranked shell model calculations, revealing a diverse range of quasiparticle configurations. At spins of around 50¯h, there is evidence for a change from dominant prolate collective motion in the yrast band and its signature partner to oblate non-collective structures via the mechanism of band termination. A possible strongly deformed triaxial band occurs at these high spins, which indicate collectivity beyond 50¯h. The high-spin structures of data are interpreted within the framework of cranked Nilsson-Strutinsky calculations.

Item Type: Thesis (Doctor of Philosophy)
Additional Information: Date: 2012-07 (completed)
Subjects: ?? QC ??
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 17 Jan 2013 10:25
Last Modified: 16 Dec 2022 04:36
DOI: 10.17638/00006815
  • Nolan, Paul