SBIR-STTR Award

The coupling of a pulsed neutron source and a depth-sensitive Compton camera based on fast inorganic scintillation crystals is proposed as a means for imaging high explosives and other materials at intermediate to long 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 during Phase I will not only allow precise depth-imaging, but they will also enable the position-sensing of the gamma-ray interaction location. The main focus of the Phase I research is optimizing the spatial resolution of a fast scintillation crystal bounded by two photomultiplier tubes using both: a) the variation in scintillation light intensity that reaches the ends of the crystal, and b) using the time-of-arrival differences between the measured light pulses. The results from both methods will be quantified and the optimal design will be tested using a diagnostic detector based on two-components. The angular resolution will be measured and modeled and the performance of the full-scale detector will thus be established, the fabrication of which will proceed during Phase II.

A depth-sensitive Compton camera based on fast inorganic scintillators is proposed as a means to rapidly image high explosives and other organic materials at intermediate to long ranges. The feasibility of the method, established during the Phase I research, will be demonstrated during Phase II, when diagnostic and scaled prototype detectors will be implemented. When coupled to an intense pulsed neutron source, the fast response and sizable detection areas of BaF2 scintillators permit the rapid imaging of the environment in a relatively economical package. Furthermore, the vigorous competition from background gamma-rays can be managed by deploying a segmented detector, which permits the use of a single high intensity neutron pulse or a rapid series of smaller pulses. The main focus of the Phase II research is on implementing the detection scheme so that the imaging capability can be optimized. To that end, diagnostic detectors will be used during Year 1 of the research to develop the pulse sensing hardware and image reconstruction software that will be used in the full-scale imager. During Year 2, a scaled prototype will be implemented using detector elements optimized in size and configuration in a modular arrangement.

Keywords:
Explosives Detection, Compton Camera, Radiation Detection, Elemental Mapping, Imaging, Scintillation Materials