High-spin spectroscopy on Au and a systematic study of moments of inertia in prolate rotational bands from Dy to Tl

Author

Wilhelm Friedrich Mueller

Date of Award

5-1997

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Leo L. Riedinger

Abstract

High-spin states have been studied in ¹⁸¹Au and ¹⁷⁹Au nuclei for the first time. These are the most neutron-deficient Au isotopes which have been studied in detail. Excited states in ¹⁸¹Au were populated by the ¹⁵⁰Sm(³⁵Cl,4n) heavy-ion fusion reaction, and studied at the Oak Ridge Holifield Heavy-Ion Research Facility with the Spin Spec-trometer and 19 Compton-suppressed Ge detectors. Eight prolate rotational bands have been established in the analysis of this nucleus. Bands based on πh_9/2, πf_7/2, πi_13/2, and πh_11/2 configurations have been clearly identified. In addition, there is a structure of high-lying states feeding at high spins into the πi_13/2 band in ₁₈₁Au. Of the two observed side bands, one has been identified as a rotational band base on the three quasiparticle excitation π1/2 [660] ⊗ v1/2[521] ⊗ v5/2|[512], and the second has been suggested as the unfavored signature of the πi_13/2 band. A final observed band has been suggested as the unfavored signature of the πf_7/2 configuration. The experiment to study high-spin states in ¹⁷⁹Au took place at the AT-LAS facility at Argonne National Laboratory. The AYE-ball array of 19 Compton-suppressed Ge detectors was used in conjunction with the Fragment Mass Analyzer and a double-sided silicon strip detector to make the first positive identification of excited states in ¹⁷⁹Au by the recently developed method of Recoil Decay Tagging. These states were populated in a ¹²⁴Te(^{58,/sup>Ni,p2n) reaction. From the study, the πi_13/2 band was clearly established, and a lower limit of 592 keV is determined for the bandhead energy. Three other bands have been observed in the this nucleus with suggested configurations assignments of πh_9/2 and πd_3/2. In addition to the study of 181Au and 179Au, a systematic analysis was made of moments of inertia of ground-state rotational bands in even-even nuclei and πh_9/2 and πi_13/2 bands in odd-Z even-N nuclei. From the study of even-even nuclei, an em-pirical relationship was developed from experimental data where by the deformation of a nucleus can be inferred from the moment of inertia with very good correlation to other observables. This relationship is applied to measured moments of inertia in intruder (πh_9/2 and πi_13/2) bands using theoretically determined deformation param-eters. Prom this comparison, it can be concluded that the amount of deformation enhancement caused by the occupation of an intruder orbital is underpredicted in some regions.}

Recommended Citation

Mueller, Wilhelm Friedrich, "High-spin spectroscopy on Au and a systematic study of moments of inertia in prolate rotational bands from Dy to Tl. " PhD diss., University of Tennessee, 1997.
https://trace.tennessee.edu/utk_graddiss/9567