Reducing edge effects and improving position resolution in position sensitive NaI (Tl) detectors

Large two-dimensional position-sensitive NaI(Tl) crystals used in positron emission tomographs and elsewhere normally have gaps or inactive, unusable areas at the edges. Experiments aimed at reducing these edge effects were performed. Unencapsulated crystals were used to test the feasibility of optically coupling crystals together to decrease gap size. Other experiments tried to increase the sampling of the scintillation light at the edges in order to obtain better position sensitivity. Work was also performed to treat the edges to reduce unwanted reflections 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.<>