Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Engineering Physics

First Advisor

Larry W. Burggraf, PhD


This work demonstrates the first instantiation of the FitzGerald Rotating Scatter Mask (RSM) as a proof-of-concept for two-dimensional source direction determination using a single, inexpensive, non-cooled scintillator, as well as an alternate mask design for comparison. A large RSM was additively manufactured from low-Z, acrylic like material, and rotated around the ubiquitous standard 3" x 3" NaI(Tl) or NaI(Tl)/CsI(Tl) phoswich detector, set internally to the mask. Smaller versions of the FitzGerald and alternate RSM designs were 3D printed for testing and used in conjunction with a LaBr detector to characterize the RSM system with a size and weight reduction applied. A simplified, analytic, attenuation by Compton scatter of the Full-Energy Peak (FEP) model, based on a Beer-Lamberts law relationship was built, developed, and applied to the design geometry of the RSMs. This model is later parameterized and used in conjunction with experimental results to create detector response matrix (DRM) libraries for both the FEP and Compton continuum portions of the spectra. Source directions were successfully predicted over the 3π steradian acceptance angle of the system, with an average resolution determined to be ~4° when using the FEP attenuation by scatter-out based library for comparison.

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