Degree Type

Dissertation

Date of Award

1993

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Fred K. Wohn

Abstract

The properties of low-and high-spin levels in [superscript]198Bi have been studied with the [superscript]181Ta([superscript]22Ne,5n)[superscript]198Bi reaction at 116 MeV and 120 MeV bombarding energies. Levels along and near the yrast lines, including one isomer, were established up to spin J ≈ 30\hbar. The main configurations of these states are suggested to be [pi] h[subscript]9/2 coupled to the known excited states in [superscript]197Pb. A sequence of states built on the excitation of the odd proton (coupled to one, two, or three quasi neutron-holes) was observed. In addition, at least two collective bands were observed. These two bands are backbending bands and are suggested to be oblate collective structures built on oblate proton and possibly neutron states;A superdeformed (SD) band was observed for the first time in an Au isotope. The reaction used was [superscript]11B + [superscript]186W, demonstrating that very light ions can be used to populate SD bands at high angular momentum. The band is assigned to [superscript]191Au. The [gamma]-ray energies are at the so-called quarter-point energies of the [superscript]192Hg SD band, indicating that the [superscript]191Au SD band is "identical" to that of [superscript]192Hg;A search for resonant states in low-energy e[superscript]+e[superscript]- scattering through their decay to multi-photon final states was performed using e[superscript]+ from [superscript]68Ga sources and a Pb absorber. Energy-sum and invariant mass spectra of coincident 2[gamma] and 3[gamma] events were obtained using the 20-element High Energy-Resolution Array (HERA) facility. No evidence for resonant states was found, and upper limits for the partial decay widths of such resonances were established in the energy range from 1.1 to 1.8 MeV.

DOI

https://doi.org/10.31274/rtd-180813-12770

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Duc Ta Vo

Language

en

Proquest ID

AAI9414031

File Format

application/pdf

File Size

158 pages

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