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Full-Text Articles in Nuclear Engineering

Enabling Mobile Neutron Detection Systems With Clyc, Matthew C. Recker Sep 2019

Enabling Mobile Neutron Detection Systems With Clyc, Matthew C. Recker

Theses and Dissertations

Cs2LiYCl6:Ce3+ (CLYC) has the desirable property of being sensitive to both gamma rays and neutrons while producing waveforms suitable for pulse shape discrimination (PSD) to determine which radiation was detected. This dissertation examines the behavior of CLYC to support its further development for mobile and portable applications. First, the feasibility of performing PSD with CLYC and an inexpensive data acquisition system was examined. This system was able to clearly distinguish both events with a figure of merit of 1.42. Next, the performance of a SiPM was compared to a traditional PMT. Analysis showed that ...


Investigations Of Point Defects In Kh2Po4 Crystals Using Ab Initio Quantum Methods, Tabitha E. R. Dodson Sep 2019

Investigations Of Point Defects In Kh2Po4 Crystals Using Ab Initio Quantum Methods, Tabitha E. R. Dodson

Theses and Dissertations

Potassium dihydrogen phosphate (KH2PO4, or commonly called KDP) crystals can be grown to large sizes and are used for many important devices (fast optical switches, frequency conversion, polarization rotation) for high powered lasers. The nonlinear optical material has a wide intrinsic transparency range. Intrinsic point defects are responsible for several short-lived absorption bands in the visible and ultraviolet regions that affect high-power pulsed laser propagation. The primary intrinsic defects have been experimentally detected in KDP using electron paramagnetic resonance (EPR) experiments. The defect models established thus far include (i) self-trapped holes, (ii) oxygen vacancies, and (iii) hydrogen ...


Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk Aug 2019

Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk

Theses and Dissertations

Electron paramagnetic resonance (EPR), Fourier-Transform Infrared spectroscopy (FTIR), photoluminescence (PL), thermoluminescence (TL), and wavelength-dependent TL are used to identify and characterize point defects in lithium gallate and β-gallium oxide doped with Mg and Fe acceptor impurities single crystals. EPR investigations of LiGaO2 identify fundamental intrinsic cation defects lithium (VLi) and gallium (V2−Ga) vacancies. The defects’ principle g values are found through angular dependence studies and atomic-scale models for these new defects are proposed. Thermoluminescence measurements estimate the activation energy of lithium vacancies at Ea = 1.05 eV and gallium vacancies at Ea > 2 eV below the ...


Development Of A Mixed-Radiation Directional Rotating Scatter Mask Detection System, Bryan V. Egner Mar 2019

Development Of A Mixed-Radiation Directional Rotating Scatter Mask Detection System, Bryan V. Egner

Theses and Dissertations

Previous work demonstrated gamma-ray directional detection through the integration of a radiation detection system and an additively manufactured rotating scatter mask (RSM). This work advances the RSM directional detection system through improvements in the system's design, validation of a new scatter mask, and the novel ability to directionally detect both neutrons and gamma rays, a desirable feature for many nuclear safeguard and counterproliferation applications. The mixed-radiation RSM system developed for this research utilized the Spartan I mask design coupled with a 1" EJ-309 liquid scintillator. A GEome-try ANd Tracking (Geant4) model is developed and quantitatively compared to experimental measurements ...