REDUCING EDGE EFFECTS AND IMPROVING POSITION RESOLUTION IN POSITION-SENSITIVE NAI(TL) DETECTORS

Large two dimensional position sensitive NaI(Tl) crystals used in posi tron emission tomographs and elsewhere normally have gaps or inactive, unusable areas at the edges. Experiments aimed at reducing these edge effects have been performed. Unencapsulated crystals have been used t o test the feasibility of optically coupling crystals together to decr ease gap size. Other experiments increased the sampling of the scintil lation light at the edges in order to obtain better position sensitivi ty. Work was also performed to treat the edges to reduce unwanted refl ections and increase the position sensitive area. Finally, experiments aimed at improving the position resolution throughout the crystal as well as at the edges were performed.