An active interrogation detection system (ACTINIDES) based on a dual fast neutron/gamma-ray coded aperture imager

We report on the initial characterization efforts for an active interrogation detection system (ACTINIDES) for applications in maritime security. The ACTINIDES concept is based on neutron/gamma-ray detection, measurement and imaging using a coded aperture mask and an array of liquid scintillator detectors. The coded mask is based on a modified uniformly redundant array (MURA) with hybrid mask elements comprised of high-density polyethylene and lead. The detector array is composed of thirty liquid scintillators. Liquid scintillator detectors are sensitive to both neutrons and gamma rays, with discrimination between the two accomplished by measurement of differences in the de-excitation light pulses. The proof-of-concept study of the instrument has been conducted passively in the laboratory; ultimately, the fully scaled-up instrument is designed to be used in tandem with an active interrogator. Results from the full laboratory test campaign will be presented, along with future prospects for work with an active interrogator.