Detection of chemical explosives using a template-matching procedure

Full text: Methods to detect chemical explosives quickly and from a standoff distance are, unfortunately, needed in order to protect troops and civilians from improvised explosive devices. Backscatter radiography and trace detection methods are being used but have limitations. Our group has been investigating a template-matching procedure, which compares a collection of responses (signatures) obtained by interrogation of a target, using photon and/or neutron beams, to templates stored in a library. Each template consists of the same collection of signatures that would be produced by a target containing an explosive in a given configuration. The template-matching procedure is relatively straightforward and leads to figure-of-merit metrics that can be used, in principle, to differentiate safe from dangerous targets. The entire process is called signature-based radiation scanning, because it involves scanning a target, by sequentially interrogating volumes of the order of several hundred cm3 using one or more radiation beams, and analyzing a set of signatures. The template-matching procedure incorporates uncertainties in the measured signatures and allows nonuniform weighting of the signatures. The template-matching procedure is described and experimental results based on early neutron interrogation studies are presented. (author)