Three layer GSO depth-of-interaction detector for high energy camera

3層DOI検出器による高エネルギー線対応型カメラ

山本 誠一*; 渡部 浩司*; 河地 有木; 藤巻 秀; 加藤 克彦*; 畑澤 順*

Yamamoto, Seiichi*; Watabe, Hiroshi*; Kawachi, Naoki; Fujimaki, Shu; Kato, Katsuhiko*; Hatazawa, Jun*

Using GSOs of different Ce concentration, three layers DOI blcok detectors were developed to reduce the parallax error at the edges of the pinhole caemra for high energy photons. GSOs with Ce concentrations of 1.5 mol% (decay time 40 ns), 0.5 mol% crystal ( 60 ns), 0.4 mol% ( 80 ns) were selected for the depth of interaction (DOI) detectors. These three types of GSOs were optically coupled in depth direction, arranged in 22 22 matrix and coupled to plat panel photomultiplier tube (FP-PMT, Hamamatsu H8500). Sizes of these GSO cells were 1.9 mm 1.9 mm 4 mm, 1.9 mm 1.9 mm 5 mm, and 1.9 mm 1.9 mm 6 mm for 1.5 mol%, 0.5 mol%, and 0.4 mol%, respectively. With these combinations of GSOs, all spots corresponds to GSO cells were clearly resolved in position histogram. Pulse shape spectra showed three peaks for these three decay times of GSOs. The block detector was contained in a 2cm thick tungsten shield and pinhole collimator with 0.5 mm aperture was mounted. With using the pulse shape discrimination, energy resolution as well as spatial resolution for Cs-137 photons was improved at the edge of the detector where the photons entered with angle. The DOI detection was effective for pinhole camera for high energy photons.