Date of Award

Spring 2022

Project Type

Thesis

Program or Major

Physics

Degree Name

Master of Science

First Advisor

Mark L McConnell

Second Advisor

James Ryan

Third Advisor

Harald Kucharek

Abstract

All orbiting spacecraft are susceptible to space radiation that can cause permanent damage to spacecraft electronics. The atmospheric neutron flux is one of the potential candidates that give rise to space radiation. To extend the atmospheric neutron study as a function of various geophysical and observational parameters (like magnetic rigidity, altitude, and phase of the solar cycle), the NASA COMPTEL (Compton Telescope) instrument on-board the CGRO (Compton Gamma Ray Observatory) spacecraft had been used to measure the spatial and temporal variation of neutrons. We used gamma-ray telescopic mode to measure the instrumental 2.2 MeV line that arose from the thermal neutron being captured by a proton in the D1 module. Hence, the 2.2 MeV line served as a surrogate for the albedo neutron flux. To support the CRAND (Cosmic Ray Albedo Neutron Decay) theory, systematic measurements of the 2.2 MeV line rate were done as a function of various parameters primarily geomagnetic rigidity ranging from 4-18 GV, geocentric elevation 0-180, and spacecraft altitude ranging from 325-525 km. Using the Morris et al. neutron fit function, the estimated line rate was calibrated to obtain measured neutron flux. To evaluate our findings, the measured neutron flux data was compared with Claret et al. simulated neutron data at solar minimum and solar maximum and also. Our neutron measurements follow the same trend as the simulated data.

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