A neutron based scanner to detect explosives in small, sealed containers

A scanning system has been designed for portal protection applications, with the capability of detecting explosive materials after an initial scan of 30 seconds. The scanner operates using the principle of neutron induced return gamma-ray spectrometry. This system utilizes high purity germanium detectors, a neutron generator based on deuterium-tritium fusion and a unique neutron reflector and guide design. The neutron reflector amplifies the flux and alters the energy spectrum of neutrons produced by the generator. A depleted uranium reflector is shown to perform 7.3 times better than no reflector, and is found to perform 1.5 times better than a tungsten reflector using MCNP simulation. This improvement is due to neutron knockout and induced fission occurring in depleted uranium. The system is capable of detecting 300g of explosives with 90% detection probability, which includes a 15% rescan rate after a 30 second initial scan.