Low-Temperature Scintillation Properties of CaWO4 Crystals for Rare-Event Searches

TL;DR

This study investigates the low-temperature scintillation properties of CaWO4 crystals, revealing temperature-dependent decay times and alpha/gamma light yield ratios, crucial for rare-event detection in cryogenic conditions.

Contribution

First measurement of CaWO4 scintillation decay times and alpha/gamma light yield ratio dependence at cryogenic temperatures for rare-event searches.

Findings

Long decay component in ms range below 40K.

Alpha/gamma light yield ratio decreases by 8-15% at low temperatures.

Temperature dependence of scintillation properties aids in event discrimination.

Abstract

In prospect of its application in cryogenic rare-event searches, we have investigated the low-temperature scintillation properties of CaWO4 crystals down to 3.4 K under {\alpha} and {\gamma} excitation. Concerning the scintillation decay times, we observe a long component in the ms range which significantly contributes to the light yield below 40K. For the first time we have measured the temperature dependence of the {\alpha}/{\gamma}- ratio of the light yield. This parameter which can be used to discriminate {\alpha} and {\gamma} events in scintillating bolometers is found to be about 8-15% smaller at low temperatures compared to room temperature.