EXDEP/CTX: an explosive detection system for screening luggage with high energy X-rays

A novel technique for detecting explosives using an RF linac has been developed. The patented EXDEP techniques uses an intense 14-MeV X-ray beam to photoactivate the nitrogen comprising >18.5% of most explosives. Activated nitrogen (t/sub 1/2/=10 min) decays, emitting a positron, which annihilates and produces two 511-keV photons that are detected. An EXDEP/CTX system has been designed to screen luggage for concealed explosives by identifying their unique combination of chemical constituents and physical density. The EXDEP technique measures the nitrogen concentration of materials on a per-unit-volume basis together with a three-dimensional computer tomography X-ray (CTX) scanner to measure their physical density. The determination of whether or not there is an explosive present is based on two factors: (1) the count rate for each volume element and (2) the number of volume elements that have the appropriate count rate. The probability of detection for the EXDEP/CTX system should be over 99% with a false alarm probability substantially less than 1%.<>