Date of Award

2015

Document Type

Thesis

First Advisor

Pedroni, Dr. Ronald S.

Abstract

The main goals of this work are an assessment of a specific Uranium-233 target to determine if it is suitable for Nuclear Resonance Fluorescence measurements; to advance fundamental nuclear-physics knowledge important for developing the nuclear materials detection capabilities using γ-rays; to provide experimental data needed for building computer models to evaluate concepts of systems for detecting special nuclear materials in cargo containers; and to educate students and young scientists in basic nuclear-physics and the experimental techniques relevant to the mission of the Domestic Nuclear Detection Office (DNDO) at the Department of Homeland Security (DHS). The Nuclear Resonance Fluorescence (NRF) measurements are carried out at the Triangle Universities Nuclear Laboratory (TUNL) using the High Intensity Gamma-rays Source (HIγS) facility. An assessment of the Uranium-232 contaminant in the sample was made as part of our efforts to measure the radioactive decay and to develop techniques for making NRF measurements on Uranium-233. For the assessment, the energy of the γ-rays emitted from the target without an incident γ-ray beam was measured using high-purity germanium (HPGe) detectors. The collaboration is trying to develop techniques that will help enable NRF measurements of Uranium-233 in addition to other radioactive targets. The nominal energy range covered by the measurements is from 2 to 5 MeV, where the transmission of gamma-rays through steel is close to the maximum value. The overall objectives of the collaboration is to make NRF measurements on actinides. The work in this thesis is a part of the effort to carry out (γ,γ’) measurements on Uranium-233. A substantial goal is to obtain signal above the background signal due to the radioactivity of the sample itself. A sample assaying is an important part of developing experiments for performing NRF measurements on radioactive samples. In this thesis, the techniques used to assay the radioactive compounds of the Uranium-233 sample is described. What we want to know about our sample is the radioactive decay, can it be used for NRF measurements, its age and how much Uranium-232 contamination is present. In addition a database for the measurements will be created on the TUNL Web site as a national resource for researchers.

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