Inter-crystal optical crosstalk: modeling in GATE and experimental validation

High resolution radiation detectors involves using small scintillating crystals optically isolated between each-other. To optimize detectors for avoiding spatial and energy performance detriment, the understanding of inter-crystal crosstalk is of great interest. Accurate optical Monte Carlo simulation plays a crucial role in this context. In this work we focused on inter-crystal optical photon crosstalk. We optimized the validated look-up table Davis Model to accurately simulate optical photons refraction at crystal interfaces using the toolkit GATE, with the goal of including accurate inter-crystal optical crosstalk in detector optimization. The crystal interfaces and bulk and optical properties of the materials were accurately modeled. Illustrative results showed an optical crosstalk of less then 1.35% when using two coupled 3 × 3 × 15 mm3 bismuth germanate crystals. The transmission model will be validated against experimental measurements and made available to GATE users. Complete simulations will be performed and will include the modeling of optical photons transport, reflection, refraction and detection using the software GATE, as well as a complete simulation of SiPMs at micro-cell level.