Optimization of Light Collection from Crystal Scintillators for Cryogenic Rare Decay Experiments

The aim of this work is optimization of light collection in conditions similar to that in cryogenic scintillating bolometers. Energy resolution and relative pulse amplitude of scintillation detectors were measured using CaWO4 crystals with different shapes (cylindrical, hexagonal, cube and triangle prism), reflector materials and shapes, optical contact and surface conditions (polished and diffuse). Light collection was simulated using the ZEMAX ray-tracing software. The results of the simulations are in good agreement with the measured values of light output. Scintillators in the shape of a triangular prism with diffused surface surrounded by an external mirror shaped as truncated cone provide the highest light collection efficiency.