Inter-Crystal Optical Crosstalk in Radiation Detectors: Monte Carlo Modeling and Experimental Validation

High-performance radiation detectors often employ crystal arrays where light can leak between them, a phenomenon called inter-crystal crosstalk, which demands mitigation for optimal detector performance. The complexity of measuring optical crosstalk in conventional detector geometries makes optical Monte Carlo simulation essential to study and reduce crosstalk through better designs. Addressing the absence of validated transmission models in Monte Carlo toolkits, we developed and integrated a new simulation model into the look-up table Davis Model, aiming at simulating optical photon refraction at crystal interfaces using GATE. For the first time, we validated the inter-crystal optical crosstalk model with experiments in two optically coupled LYSO crystals read by two SiPMs, testing three thicknesses and four interfaces (air, glue, Teflon, ESR). Simulated and experimental crosstalk agreed within one FWHM for all configurations. These results show the possibility of predicting optical photon transmission in detector designs with multiple crystal elements. Indeed, although validated using only two crystals, the model can be used in more complex geometries. The model, available to GATE users upon request, provides a valuable resource for researchers when optimizing detector geometry where optical crosstalk needs to be considered, i.e., ensuring optical isolation between the photodetector’s responses.