The CRILIN calorimeter: gamma radiation resistance of crystals and SiPMs

TL;DR

This study evaluates the gamma radiation resistance of PbF$_2$ and PbWO$_4$-UF crystals and SiPMs for use in the CRILIN calorimeter at the Muon Collider, highlighting their durability and potential for high-radiation environments.

Contribution

It provides new comparative data on the radiation hardness of PbF$_2$ and PWO-UF crystals and SiPMs, informing material choices for radiation-tolerant calorimeters.

Findings

PbF$_2$ crystals show partial transmittance recovery after irradiation.

PWO-UF crystals maintain stable transmittance under gamma radiation.

SiPMs exhibit increased dark current and breakdown voltage post-irradiation.

Abstract

The Crilin calorimeter is a semi-homogeneous calorimetric system based on Lead Fluoride (PbF$_2$) crystals with UV-extended Silicon Photomultipliers (SiPMs) proposed for the Muon Collider. This study investigates the radiation resistance of crystals and SiPMs, subjected to 10 kGy gamma irradiation, equivalent to a 10-year service life in the Muon Collider. Our findings indicate that while PbF$_2$ crystals exhibit a decrease in transmittance post-irradiation with partial recovery over time, the alternative PbWO$_4$-Ultra Fast (PWO-UF) demonstrates exceptional radiation hardness, maintaining stable transmittance. SiPMs showed an increase in dark current and breakdown voltage post-irradiation, with less degradation observed in the SiPM biased during the exposure to radiation compared to the unbiased component. These results underscore the viability of PbF$_2$ for radiation-tolerant calorimeters, though improvements in production homogeneity are needed. The superior performance of PWO-UF crystals suggests they are a promising alternative for high-radiation applications, but their higher cost must be carefully considered.