Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive
neutron detection systems. The main reason for having neutron detection capability is to detect fission
neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and
Science Applications International Corporation (SAIC) use neutron detectors based upon 3 He-filled gas
proportional counters, which are the most common large neutron detector. There is a declining supply of 3 He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated.
Lithium Loaded Glass Fiber Neutron Detector Tests