Three techniques (API, PFNA and PFTNA) are described and compared in this brief review of neutron based technologies for the detection of contraband in cargo containers. It appears that the role that these techniques can play in the detection of contraband in Customs, airline security and physical security applications remains to be demonstrated. However, their utilization in the fields of non-proliferation, arms control and disarmament, radwaste remediation and pollution control seems more straight forward since the issues of thruput and radiation safety are not so critical.
Siraj M. Khan,
"Review of neutron-based technologies for the inspection of cargo containers", Proc. SPIE 2276, Cargo Inspection Technologies, (6 October 1994); doi: 10.1117/12.189178; https://doi.org/10.1117/12.189178