A Neutron Based Interrogation System For SNM In Cargo

Abstract

A complete system has been simulated using experimentally obtained input parameters for the detection of special nuclear materials (SNM). A variation of the associated particle imaging (API) technique, referred to as reverse associated particle imaging detection (RAPID), has been developed in the context of detecting 5‐kg spherical samples of U‐235 in cargo. The RAPID technique allows for the interrogation of containers at neutron production rates between ∼1×108 neutrons/s and ∼3×108 neutrons/s. The merit of performance for the system is the time to detect the threat material with 95% probability of detection and 10−4 false positive rate per interrogated voxel of cargo. Detection times of 5 minutes were found for a maximally loaded cargo container uniformly filled with iron and as low as 1 second in containers loaded to ¼ of full capacity with either iron or wood. The worse case system performance, 30 minutes interrogation time, occurs for a maximally loaded container containing wood at 0.4 g/cm3.