Characterisation of Silicon Photomultipliers for Liquid Xenon Detectors

TL;DR

This study characterizes silicon photomultipliers (SiPMs) for use in liquid xenon detectors, focusing on their performance at cryogenic temperatures, stability, and radioactivity levels, demonstrating their suitability for low-background radiation detection applications.

Contribution

The paper provides a comprehensive characterization of Hamamatsu SiPMs at cryogenic temperatures, including stability, noise, and radioactivity, supporting their application in liquid xenon detectors.

Findings

SiPMs maintain stable single-photon response at cryogenic temperatures.

Dark and correlated noise rates are low and manageable.

Radioactivity levels of SiPM materials are suitable for low-background experiments.

Abstract

Silicon Photomultipliers (SiPMs) are considered as a solid-state sensor alternative to photomultiplier tubes in experiments using liquid xenon (LXe) as a radiation detection medium. The main requirements are single-photon detection of the vacuum ultraviolet scintillation light from LXe at 178$\,$nm with high resolution and detection efficiency and low noise rates. Further requirements for dark matter and double beta decay searches are ultra-low radioactivity levels of all the components including the substrates and cold electronics. Here we describe our characterisation of Hamamatsu 6$\times$6$\,$mm$^2$ SiPMs in the temperature range 110-300$\,$K in nitrogen gas, as well as long-term measurements in cold nitrogen gas at 172$\,$K and liquid xenon at 185$\,$K. After we introduce the experimental setups, the data acquisition schemes and analysis methods, we show the single-photon response, the gain versus bias voltage, as well as the dark and correlated noise rates. We demonstrate the long-term stability at cryogenic temperatures, and conclude that SiPM arrays are promising candidates for photosensor arrays in liquid xenon detectors. Furthermore, we study the radioactivity of the raw SiPM materials with gamma spectrometry and inductively coupled plasma mass spectrometry and conclude that SiPMs are suitable for use in low-background experiments.