Active Interrogation System for Detecting and Identifying SNM

Active interrogation holds the most promise for detecting heavily shielded materials at a distance. This effort will use pulsed neutron excitation of fission reactions in the target being inspected in conjunction with an imaging detector. Special nuclear material (SNM) that is present will undergo fission reactions that generate prompt and delayed neutrons which will be emitted by the target. The presence of emitted neutrons will indicate that SNM may be present. Recording the time course of the delayed neutron emissions will provide additional information about the target identity. We will examine the design and construction of a complete active interrogation system including a compact neutron generator and fast neutron imaging detector. Imaging offers several significant advantages: interrogating the entire target simultaneously, improving the signal-to-background ratio, and distinguishing between real threats and false alarms. The system will be based on an RF-Plasma neutron generator design from Lawrence Berkeley National Laboratory (LBNL) and the fast neutron imaging telescope (FNIT) being developed at the University of New Hampshire.