Thesis (Ph. D.)--University of Washington, 1993. / Vita. Includes bibliographical references (leaves [176]-189).

Thesis (M. Phil.)--University of Hong Kong, 1996. / Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, August 2000. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 62-64). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 155-158).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Magister Scientiae - MSc / Gamma ray spectroscopy has provided enormous amounts of information on the behaviour and structure of atomic nuclei [SHA88, BEA92, EBE08]. Most of the major discoveries in experimental nuclear physics over the last five decades are strongly associated with improvements in detector technologies. Inorganic scintilators led to the discovery in 1963 of the first excited states of a rotational band based on the ground state of 162Dy. Improvements in peak-to-background ratios and detector resolutions obtained with germanium led to the first evidence of backbending which is associated with a two quasi-particle excitation in 162Dy [SHA88]. More recently the development of composite and highly-segmented Ge detectors has significantly increased the performance and power of detection systems. The Clover detector is such a detector system and is in use at iThemba LABS. This study concerns the evaluation of the particle transport code MCNPX 2.5.0 as a tool to model complex composite detectors such as the Clover. Lanthanum silicate (LSO) and Lead tungstate (PbWO) are also evaluated as possible suppressor shield materials. It is shown that reasonable agreement between experiment and simulation is found when the experiment is accurately reproduced. However, when complex detection modes are implemented in the detector based on the number of elements that fire, MCNPX cannot be used to model the detector performance exactly. Differences between simulated and experimental results are found in suppressed add-back mode. It is proposed that the discrepancies are due to limitations in implementation of the pulse-height and special anti-coincidence tally in MCNPX. LSO and PbWO are compared to BGO as suppressor shield materials. It is found that LSO is not an ideal material for a suppression shield. PbWO is shown to give performance values similar to that of BGO. The back-plug is shown to have no effect on the Peak-to-Total ratio but is effective at reducing the background at lower energies. / South Africa

We have performed a blind search for a gamma-ray transient of arbitrary duration and energy spectrum around the time of the LIGO gravitational-wave event GW150914 with the six-spacecraft interplanetary network (IPN). Four gamma-ray bursts were detected between 30 hr prior to the event and 6.1 hr after it, but none could convincingly be associated with GW150914. No other transients were detected down to limiting 15-150 keV fluences of roughly 5 x10-(8) -5 x 10(-7) erg cm(-2). We discuss the search strategies and temporal coverage of the IPN on the day of the event and compare the spatial coverage to the region where GW150914 originated. We also report the negative result of a targeted search for the Fermi-GBM event reported in conjunction with GW150914.

The success of many experiments at rare-isotope facilities, such as the National Superconducting Cyclotron Laboratory (NSCL), depends on achieving a level of statistics that is partly driven by the overall number of nuclei produced in the beam. One such future study at the NSCL requires maximizing the beam content of 34mCl. To prepare for this 34mCl study, an initial measurement to determine the 34mCl yields and overall beam purity was performed at the NSCL by utilizing a Beta-decay experimental station. Isotopes delivered to the experimental station were identified using standard time of flight and energy loss techniques. To explore ways of maximizing 34mCl production, 6 different beam energy settings that selected different rigidities for isotopic selection and altered its entrance angles before the beam went into the fragment separator, were utilized. The absolute intensity of the peak energies associated with the decay of 34mCl (1177, 2127, and 3304 keV) were determined, as well as the overall number of 34Cl atoms delivered, thereby enabling 34mCl yield and beam purity determinations for each beam setting.

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