Observation of /sup 238/U photofission products

Sophisticated solutions are being developed by researchers to improve detection of clandestine fissile material. In this work, a simpler approach is investigated as an interim solution. Using the existing 9-MeV X-ray radiography units deployed for cargo inspection, delayed fission product gamma rays from induced photofission are seen minutes after probing a small sample of /sup 238/U. By acquiring both time and energy information, a relatively large number of usable fission products can be identified. Using the radiographic images along with an efficient portable scintillator capable of detecting gamma rays above 3 MeV may provide a cost-effective improvement to existing inspection systems.