Studies of scintillation properties of CaMoO4 at millikelvin temperatures

TL;DR

This study investigates the scintillation properties of CaMoO4 at millikelvin temperatures using a specialized low-temperature detection module, revealing key decay constants and energy resolution relevant for cryogenic rare event detection.

Contribution

It introduces a novel measurement setup with a low-temperature photomultiplier to study CaMoO4 scintillation at millikelvin temperatures, providing new data on decay times and energy resolution.

Findings

Energy resolution of 30% at 122 keV

Fast decay constant of 40.6 microseconds

Slow decay constant of 3410 microseconds

Abstract

Application of CaMoO4 as a scintillation target in cryogenic rare event searches relies on the understanding of scintillation properties of the material at the temperatures at which these detectors operate. We devised and implemented a detection module with a low-temperature photomultiplier from Hamamatsu (model R8520-06) powered by a Cockcroft-Walton generator. The detector module containing the CaMoO4 crystal was placed in a 3He/4He dilution refrigerator and used to measure scintillation characteristics of CaMoO4 in the millikelvin temperature range. At the lowest temperature achieved, the energy resolution of CaMoO4 for 122 keV from a 57Co source is found to be 30% (FWHM), and the fast and slow decay constants are 40.6+-0.8 us and 3410+-50 us, respectively. The temperature variation of the CaMoO4 decay kinetics is discussed in terms of a three-level model of the emission center