Evaluation of reflective separators for arrays of small crystals used with avalanche photodiodes

Thin, highly reflective, opaque separators are required for compact arrays of small discrete scintillation crystals used in conjunction with pixellated photodiode readouts in high-resolution imaging applications. Mechanical stability, individual detector performance, and cost are the main factors to be considered in the choice of a suitable separator. Five different types of reflective separators were tested with 4×4 arrays of BGO, LSO and CsI(Tl): white reflector paint, white epoxy, a composite separator made of metallized Mylar(C) coated with white paint, white plastic and Mylar(C)-Al. The light output and intrinsic resolution of individual crystals in the arrays were measured as a function of energy and the results were compared to simulation of light collection efficiency obtained with DETECT97