A new compact position-sensitive PMT for scintillation detectors

A new compact position-sensitive photomultiplier tube (PS-PMT), Hamamatsu R7600-C12 [1], has been developed for scintillation detectors. The PS-PMT has 11 stages of metal channel dynodes [2] and 6(X) + 6(Y) crossed plate anodes in a 25.7 mm square x 20 mm high metal can package, where the;photo-sensitive area is 22 mm square. The performance of the PS-PMT was evaluated in terms of applicability to radiation imaging systems. In comparison with the former type of PS-PMT (Hamamatsu R5900-C8 [3]), the new PS-PMT provides smaller light spread and better position response. Also, by removing the flange at the bottom of the PS-PMT, the ratio of the effective area to the outward area is increased. The spatial resolution capability was demonstrated by imaging a stratified LSO array having an element of 1.8 mm x 1.8 mm x 10 mm. Each crystal element is clearly identified on the image map with 662 keV uniform gamma-ray irradiation. This paper describes the characteristics of the new PS-PMT and the experimental results for a gamma-ray imaging detector.