Doctoral Dissertations

Date of Award

5-2002

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Leo L. Riedinger

Committee Members

Carrol Bingham, Witek Nazarewicz, Larry Townsend

Abstract

This dissertation reports the observation of high-spin states in the neutrondeficient 128•129Nd and 130La nuclei from three fusion evaporation experiments. In one experiment, high-spin states in 128•129Nd were populated using the reaction 4°Ca + 92Mo. The 170-MeV 4°Ca beam was supplied by the 25 MV tandem at Oak Ridge National Laboratory. The Recoil Mass Spectrometer provided mass identification, while 1-ray and charged-particle emissions were detected by the CLARION spectrometer in conjunction with the HyBall array. In a second experiment emphasizing the highest spin states possible, the same reaction was used at a beam energy of 184 MeV provided by the ATLAS accelerator at Argonne National Laboratory. Charged-particle and 1-ray emissions were detected by the Microball array operating in conjunction with the Gammasphere spectrometer. The third experiment was performed at the Wright Nuclear Structure Laboratory at Yale University where high-spin states of 130La were populated using a 19F beam of 100 Me V average energy delivered to a 116Cd target, and the emitted 1 rays were detected by the Yrast-Ball array. For 128Nd, the previously known ground-state band has been extended to 11r = (34+) and four side bands were observed for the first time with a total of nearly 60 new transitions. A significant delay of the vh1112 crossing frequency was observed in the A ~ 130 region, with the largest values occurring consistently at N = 70. An attempt to understand the phenomenon was performed with calculations by the Cranked Shell Model (CSM) and the Projected Shell Model (PSM). The presence of octupole correlations in 128Nd and nearby even-even nuclei was also investigated.

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