PORTABLE INSTRUMENT FOR CODED-APERTURE IMAGING OF GAMMA-RAY SOURCES

A portable gamma-ray imaging system with a coded aperture is described . The system contains a position-sensitive detector encased in a lead housing. Coded masks for forming images, a unit with a shutter and a v ideocamera, an electronic unit, and a personal computer are mounted in side the housing. The detector consists of a thin CsI(Tl) scintillator (40 mm in diameter and 3 mm thick), two image intensifiers, and a CCD array. The instrument has a sensitivity sufficient for detecting a po int Cs-137 source that produces an additional dose rate of 10 mu R/h w ithin 20 min with a signal-to-background ratio of 5. The total angles of view are 24 degrees and 21.5 degrees for masks of the ninth and six th ranks, respectively. The angular resolution is 1.2 degrees, and the dynamic range is 10(6). The gamma-ray images of distributed Cs source s are presented.