Date of Award
3-2024
Document Type
Thesis
Degree Name
Master of Science in Nuclear Engineering
Department
Department of Engineering Physics
First Advisor
Jesse C. Foster, PhD
Abstract
Neutrons can cause irreparable harm to electronics, and experiments are needed to understand their effects fully. This work explores using pulsed power, which is low-cost compared to other sources, to create a useful neutron-rich environment. Deuterated polyethylene was used as anode and catcher material to generate the neutrons from the Deuterium-Deuterium (DD) fusion reaction. A simple, effective, and repeatable method was employed to directly cast deuterated polyethylene onto polyethylene sheets to fabricate the anode and catcher. The DD reactions were made by an ion beam-driven pulsed power generator, Gamble II, with the catcher located in the cathode. Zinc, copper, aluminum, and indium activation foils were used with gamma counting on High-Purity Germanium (HPGe) detectors to unfold the neutron energy spectrum from Gamble II shots. Even though significant uncertainty exists, unfolding results from two shots showed the neutron fluence varying from approximately 10^10 to 10^12 [n/cm2] in the 2.5 MeV energy range. Bubble detectors and neutron time of flight (nTOF) diagnostics were also used to complement the activation foils. While bubble detector measurements did not agree with the unfolded spectrum, they did qualitatively illustrate a strong presence of neutrons. Lastly, the nTOF data showed peaks corresponding to 1.8 and 5.2 MeV. The 1.8 MeV peak seems plausible from a deuteron-on-carbon reaction, and the 5.2 MeV peak is likely associated with 2.45 MeV neutrons. However, additional work is required to verify the presence of those neutrons. It was thought that 14.1 MeV neutrons from a Deuterium-Tritium (DT) might be possible in this experiment, but the nTOF measurements did not indicate their presence. Regardless, these results encourage the potential utilization of Gamble II as a neutron effects platform; however, further work is needed to characterize the neutron spectrum more accurately.
AFIT Designator
AFIT-ENP-MS-24-M-055
Recommended Citation
Smith, Christopher J., "Neutron Spectrum Unfolding from Activation Foils Irradiated in Gamble II using Deuterated Polyethylene Anodes" (2024). Theses and Dissertations. 7699.
https://scholar.afit.edu/etd/7699
Comments
A 12-month embargo was observed for posting this work on AFIT Scholar.
Distribution Statement A, Approved for Public Release. PA case number on file.