Masters Theses

Date of Award

12-2023

Degree Type

Thesis

Degree Name

Master of Science

Major

Nuclear Engineering

Major Professor

Jason P. Hayward

Committee Members

Jason P. Hayward, Michael Howard, Chester Ramsey, Xianfei Wen

Abstract

The focus of this research is on the preparation of a deuterated organic scintillation detector for fast and high energy neutron spectroscopy. The underlying physics of organic scintillation detectors, the process in which a neutron undergoes interaction with the detector material, as well as the readout and data processing procedure is introduced.

For methodology, a comprehensive setup of an EJ301-D deuterated organic scin- tillation detector is detailed. This includes algorithmic development for three distinct purposes. Firstly, it involves the creation of iterative unfolding algorithms, specif- ically the GRAVEL and Maximum Likelihood Expectation-Maximization (MLEM)

algorithm. The second development is conformal binning which enhances the results of unfolding. Finally, matrix condition is detailed which is useful for analyzing the outcomes of unfolding. Scintillation detector setup also includes the generation of an EJ301-D response matrix. This process involves simulating neutrons through the detector to track the recoil particles, tallying the light output response from the energy deposition of these recoil particles. Because light output response is dependent on the type of recoil particle, a method was developed for determining the proton and carbon response function using a deuteron response function. The setup of our scintillation detector also involved methods of using different gamma sources to describe calibration, resolution, and pulse processing.

An experiment was conducted using a deuterium and tritium (DT) fusion generator to determine the accuracy of the detector setup. The expected 14.1 MeV neutron peaks and the 2 to 3 MeV energy spectra deposition from residual deuterium-deuterium (DD) reactions were successfully verified. The initial analysis concluded with a sample application, wherein the prepared detector was utilized to measure neutron behavior in a proton therapy environment. Sufficient preparation and careful considerations were not undertaken for a formal analysis of dose and comparisons with other studies. Nonetheless, observations were made such that the neutron spectrum fit within the energy range of the detector, and that temporal pulse separation in the secondary neutron spectrum, correlating to pulses from the incident proton beam, could be observed. These observations offered an initial insight for the future execution of an experiment that is more formally controlled.

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