A new proof-of-principle contraband detection system

An accelerator-based technique is being developed to detect contraband materials in large containers. The source, which uses a low-energy proton beam to generate high-energy gamma rays, uses the gamma resonance absorption technique to detect nitrogen-14 and chlorine-35 in containers. Both these materials are commonly found in contraband drugs as well as in explosives. Through the use of segmented BGO detectors to detect the resonant gamma rays a quantity as low as ∼ 1 kg can be located with a considerable degree of confidence. Several stations at a port of entry can be operated with one accelerator, as described