Author ORCID Identifier

https://orcid.org/0000-0001-6587-0208

Year of Publication

2019

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Arts and Sciences

Department

Physics and Astronomy

First Advisor

Dr. Michael A. Kovash

Abstract

Despite nuclear fission prominence in nuclear physics, there are still several fundamental open questions about this process. One uncertainty is the energy distribution of neutrons emitted immediately after fission. In particular the relative energy distribution of neutrons above 8~MeV has been difficult to measure. This experiment measured the prompt neutron energy spectrum of n+235U from 3-10~MeV. The measurement took place at Los Alamos National Laboratory (LANL) and used a double time-of-flight technique to measure both the beam and fission neutron kinetic energies. Fission event timing was measured with a parallel plate avalanche counter. The fission neutron time-of-flight was measured with 2~m long plastic scintillation detectors. By combining the time-of-flight information with a known flight path the kinetic energy spectrum of neutrons was measured. To eliminate backgrounds various time-of-flight and energy cuts were imposed and an accidental coincidence background was subtracted. An MCNP simulation, including the 2~m neutron detector geometry, was done using the Madland and Nix model as the input energy distribution for the simulated neutrons. Finally, the measured energy spectrum was compared with the MCNP simulated n+235U fission neutron energy spectrum.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2019.179

Funding Information

This research was supported by the US Department of Energy grant DE-NA0003348.

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Nuclear Commons

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