Application of fast neutron spectroscopy/radiography to airport security

Research is being conducted on a new type airport security system based on pulsed fast neutron spectroscopy. A pulsed 'white neutron' source is produced from the 9Be(d,n) reaction by allowing a pulsed 5 MeV deuteron beam to impinge on a thick beryllium target. By performing sample in/sample out experiments, the neutron attenuation as a function of neutron energy is determined. From the attenuation curves, the presence and amount of hydrogen, carbon, nitrogen and oxygen in the neutron beam is determined. The determination of these four elements allows one to determine with high probability the presence of explosives.