Demonstration of a Cruciform Gamma-Ray Direction-Finder with both Self-Shielding and Compton Imaging Modes

Abstract

Effective technologies for locating radioactive materials across large areas are being developed as governments globally prepare for nuclear incidents. The present study investigates a Cruciform device that provides both Compton gamma imaging and simple direction-finding based on self shielding. The Compton imaging and selfshielding modes perform well for detecting a single medium-energy source at multiple azimuthal angles. The performance degrades, however, for both modes at higher elevation angles.The self-shielding mode can determine the source direction even for low-energy sources when the Compton-scattering mode is impossible. The Compton-scattering mode on the other hand provides gamma images of two equal-energy sources, where the self-shielding mode points to the source distribution centroid.In conclusion, the Cruciform detector helps determine distant sources, especially near the horizon. The Compton mode provides actual imaging capabilities in the presence of higher energy sources, while its self-shielding mode helps determine lowenergy sources.