Date of Award

3-2021

Document Type

Thesis

Degree Name

Master of Science in Nuclear Engineering

Department

Department of Engineering Physics

First Advisor

Darren Holland, PhD

Abstract

The goal of this work was to use the adjoint transport equation to characterize the energy spectrum of a point neutron source using the time-energy fluence at the satellite. The adjoint transport was solved via Monte Carlo methods in the new program called Space to Air High-Altitude Region Adjoint (SAHARA). A new adjoint source event estimator was developed to improve the computational efficiency. This work explores SAHARA’s performance using mono-energetic and continuous sources. In general, the identified source spectra were noticeably shifted towards lower energies, but were able to capture the source spectrum shapes. Lastly, SAHARA was applied to the real-world neutron energy spectrums of Fat Man and Little Boy. SAHARA provides a new tool for estimating the source spectrum from space-based neutron measurements.

AFIT Designator

AFIT-ENP-MS-21-M-125

DTIC Accession Number

AD1145714

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