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Title: Spectroscopy of exotic proton-rich nuclei close to A = 120
Author: Angus, Lee James
ISNI:       0000 0004 2743 2532
Awarding Body: University of the West of Scotland
Current Institution: University of the West of Scotland
Date of Award: 2012
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Three experiments have been performed in order to identify excited states ill the neutron-deficient isotopes 117La and 118,120Ba. In the first experiment, the recoil decay-tagging method has been used, utilising the, JUROGAM II germanium-detector array in conjunction with the Recoil Ion Transport Unit and the Gamma Recoil Electron Alpha Tagging spectrometer to study the 64Zn(58Ni,p4n)117La reaction. In the subsequent analysis the proton decay from the ground-state of 117La was observed with an energy and half life of Eproton = 810 (2) keY, and tl/2 = 21 (2) ms, respectively. By tagging on the 117La proton decay energy, it has been possible to observe new ,,-ray transitions between excited states in 117La. Due to the lack of counts it has not been possible to determine coincidence relationships, however, the spectra suggests that the 1fhll/2 band and possibly the 1f97/2 [422) 3/2+ band, may be the source of the observed y-rays, and hence, it is possible that the proton decaying state is fed by both of these. In the second experiment the Garnrnasphere germanium-detector array was used in standalone mode to study the 58Ni(64Zn,2p2n)1l8Ba and 58Ni(64Zn,2p )120Ba reactions. In the third experiment the same reactions were studied, this time utilising Gammasphcrc in conjunction with the Microball charged-particle detector array and the Argonne Fragment Mass Analyser. For 120Ba, the subsequent analysis has revealed a strongly-coupled rotational band, observed up to 23h and assigned a configuration of 7T[(g9/2)-lhll /2). In addition, the low-lying negative-parity band based on the 1T[g7/2hll/2) configuration has been extended up to 29h and its signature partner observed up to 26h. For llBBa, the ground-state band has been tentatively extended up to 24h, and a signature partner for the low-lying negative-parity band has been observed up to 16h. Angular-distribution coefficients been extracted and used to determine y-ray multipolarities and mixing ratios. Ratios of reduced transition probabilities B(Ml)/B(E2) and B(El)/B(E2) have also been measured and used to investigate the structure of the states.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available