| 摘要 |
An apparatus and method for detecting, locating, and analyzing chemical compounds located within a test subject using subatomic particle activation. In a first embodiment, an excitation source excites a target to simultaneously produce beams each consisting of certain subatomic species, for example fast neutrons and alpha particles. The test subject (and chemical compounds contained therein) is irradiated by the fast neutrons, thereby stimulating the emission of prompt gamma rays. Gamma and alpha detectors are positioned relative to the test subject and target(s) so as to detect the emitted prompt gamma rays and alpha particles in substantial coincidence, and the known physical relationship between the beams is used to spatially locate the activated chemical compound. Energy spectra derived from the gamma detectors are filtered to eliminate all non-relevant spectral artifacts, thereby 1) permitting the creation of a plurality of parallel coincidence channels; 2) reducing the subsequent signal processing required; and 3) increasing the overall accuracy and efficiency of the chemical compound identification and analysis processes. In a second embodiment, thermal neutron-induced gamma emissions are detected and analyzed in conjunction with the fast neutron-induced gammas to provide a warning signal of the possible presence of certain types of contraband. A multi-beam/multi-target embodiment is also disclosed for more accurate spatial location. A method for calibrating and evaluating the efficacy of the system under varying test parameters is further disclosed.
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