Radiation Resistance of the Muon Collider CRILIN Calorimeter Prototype Equipped With Cherenkov Lead Fluoride Crystals

This study investigates the radiation resistance of lead fluoride (PbF2) and PbWO4-ultra fast (PWO-UF) as light-emitting crystals for CRystal calorImeter with Longitudinal INformation (CRILIN), a semi-homogeneous calorimetric system proposed for the Muon Collider. PbF2 and PWO-UF monocrystals were exposed to 60Co gamma radiation at various steps. Possible damage recovery due to room-temperature annealing and exposure to natural light was also monitored. Irradiation tests were also carried out on a prototype of CRILIN equipped with PbF2 crystals. Optical-transmittance measurements revealed an exceptional radiation hardness for PWO-UF, whereas most of the radiation damage induced in PbF2 can be recovered with exposure to natural light. PWO-UF shows superior performance with respect to PbF2, but the cost difference must be carefully taken into consideration for the choice.