SBIR-STTR Award

The coupling of a neutron source and a Compton camera based on fast inorganic scintillation crystals is proposed as a means for imaging high explosives and other materials at intermediate ranges. The use of scintillators allows one to deploy relatively large active detection areas, which are crucial if short measurement times are going to be achieved. The temporal response of the fast scintillation component of the BaF2 crystals that we intend to use will not only mitigate pulse pile-up concerns and allow precise depth-imaging in pulsed applications, but it also enables the precise position-sensing of the gamma-ray interaction location. The main focus of the Phase I research is to develop a 3-element bar-detector design to validate the feasibility previously predicted through models and measurements, so that a scaled prototype device can be fabricated and tested in Phase II.

Keywords:
Stand-Off Detection, Neutron Interrogation, Gamma-Ray Imaging, Barium Flouride

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 (10's 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.

Keywords:
Stand-Off Detection, Neutron Interrogation, Gamma-Ray Imaging, High-Explosives, Scintillators