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Portable device for explosives' detection (SENNA) based on Nanosecond Neutron Analysis (NNA) / Associated Particles Technique (APT) has been created and tested. SENNA is a single suitcase weighting 35 kg; it is remotely controlled from any PC-compatible computer. Inside is an APT neutron generator with a 3×3 matrix of semiconductor detectors of associated alpha-particles, two BGO-based detectors of gamma-rays, fully-digital data acquisition electronics, data analysis and decision-making software, and batteries. Detection technology is based on determining chemical composition of the concealed substance by analyzing secondary gamma-rays from interaction of tagged fast neutrons with its material. A combination of position-sensitive alpha-detector and time-of-flight analysis allows one to determine the location of the detected material within the inspected volume and its approximate mass. Fully digital data acquisition electronics is capable of performing alpha-gamma coincidence analysis at very high counting rates, which leads to reduction of the detection time down to dozens of seconds. SENNA's scenario-driven automatic decisionmaking algorithm based of "fuzzy logic" mechanism allows one to detect not only standard military or industrial explosives, but also improvised explosives (including those containing no nitrogen), even if their chemical composition differs from that of standard explosives. SENNA can also be "trained" to detect other hazardous materials, such as chemical/toxic materials, if their chemical composition is in any way different from that of the surrounding materials.
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