Doctoral Dissertations

Date of Award

5-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Nuclear Engineering

Major Professor

Eric D. Lukosi

Committee Members

Jason P. Hayward, Lawrence H. Heilbronn, Stefan M. Spanier

Abstract

The radiation detection field has been rapidly growing in the recent three decades due to the Special Nuclear Materials (SNM) proliferation hazards. Monitoring and detecting SNM with high resolution has been a practical issue. Recently, Neutron Scatter Camera (NSC) addressed this issue by identifying the different SNM with high efficiency. However, the huge size of the detection system beside the poor resolution requires developing an alternative NSC. Two Diamond-based Neutron Scatter Camera (DNSC) systems were investigated. The two-diamond array demonstrated good energy resolution of reconstructing spectrum of multiple neutron sources. Moreover, the spectrum of 239PuBe source was reconstructed experimentally via the two-diamond array NSC. The measured spectrum agreed well with the peak of 3 and 10 MeV. On the other hand, the diamond array, in addition to its capability of spectroscopy, pinpointed several neutron sources. For instance, the simulated system could locate and identify a highly active 252Cf source ( 2.3*1010 n/s) placed 1 meter away within 6 hours.The Chi-Nu measurements started back in 2012 at Los Alamos National Lab to obtain more accurate data of fission neutrons. In this dissertation, a novel Double Time-of-Flight (DToF) detection system was utilized to investigate the capability of reconstructing the prompt fission neutrons spectra that were produced by the fast neutron irradiation of two fissile materials which coated a diamond detector. Unlike the Chi-Nu, DToF simulation measurements used only one type of detector (diamond detectors) for all neutron energy range. The simulation results represented good resolution but more accurate correction factors are needed for the low detection efficiency (~3%) of the system.Protecting astronauts for future space missions from galactic cosmic rays (GCR) is an issue for NASA. Identifying the light ions that strike through the spaceship craft is the first goal to design a shielding material. To address this issue, a ΔE/ΔE detector was explored for the measurement of Minimum Ionizing Particles (MIPs) using the beam-line at the NASA Space Radiation Laboratory (NSRL). The measurements were analyzed by Geant4 simulation, which showed promising results in using a ΔE/ΔE detector to define interacted isotopes.

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