High Efficiency Spectroscopic Angular Imaging via a Compton Camera using Fast Inorganic Scintillators

In order to effectively manage hazardous environments, one requires a detailed knowledge of those materials that pose a threat to valued assets. Through both detector characterization and system modeling, we demonstrated the feasibility of using a Compton Camera based on inorganic scintillators as a means to rapidly image high explosives and other organic materials at intermediate to long ranges, when they are impinged upon by a high-flux neutron stream. In particular, we evaluated five different scintillation materials- NaI(Tl), Ba2, LaCl3(Ce), bismuth germanium oxide (BGO), and CsI2, and two different configurations- cylindrical bar detector and pixellated planes. The experiments confirmed the analytical prediction that a compact (less than a cubic foot of detector material) bar-detector comprised of NaI(Tl) is a feasible method of rapidly imaging explosives at intermediate ranges (10s of meters). What remains is to optimize the light propagation characteristics of the crystals (via the boundary reflectors) and to couple the entire system together into a Phase II prototype. The main technical objective of Year 1 of the Phase II research is to thus build a demonstration instrument that is capable of HE detection and localization, which will be optimized and demonstrated during the Year 2 work.