High spin spectroscopic studies of 156Ho: shape changes and band termination

Hampson, Peter
High spin spectroscopic studies of 156Ho: shape changes and band termination. PhD thesis, University of Liverpool.

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High spin states in 156Ho have been populated through the 124Sn( 37 Cl, 5n)156Ho reaction at 177MeV as part of an experiment performed at the ATLAS facility of Argonne National Laboratory. A high statistics, high-fold γ-ray coincidence data set was collected with the GAMMASPHERE spectrometer array. Following a coincidence analysis 138 new transitions have been observed alongside a further 14 tentative transitions. A level scheme has been constructed building on previous work, which has been revised and considerably extended. A review of cranked shell model calculations, rotational alignments and B(M1)/B(E2) ratios of reduced transition probabilities has indicated that this nucleus is considerably soft with respect to triaxial deformation, which has facilitated in a reinterpretation of the configurations of four of the known bands. A further four new band structures have been identified, three of which exhibit behaviour characteristic of terminating bands. Within these structures two terminating states have been identified and valence-space interpretations have been associated with them that are consistent with known terminating bands in neighbouring nuclei. A third terminating configuration has been proposed but a corresponding terminating state has not yet been observed. An unusual backbend has been identified in a revised band structure. Following a review of nearby odd-odd nuclei it has been found that this behaviour may be systematic for odd-odd nuclei in the mass ∼160 region, however as of yet it defies a clear explanation, and therefore two possible interpretations have been presented.

Item Type: Thesis (PhD)
Additional Information: Date: 2014 (completed)
Uncontrolled Keywords: Holmium backbend terminating termination high-spin
Subjects: ?? QC ??
Depositing User: Symplectic Admin
Date Deposited: 06 Aug 2015 07:51
Last Modified: 16 Dec 2022 04:43
DOI: 10.17638/02011403
URI: https://livrepository.liverpool.ac.uk/id/eprint/2011403