Performance of Hamamatsu VUV4 SiPMs for detecting liquid argon scintillation

TL;DR

This study evaluates Hamamatsu VUV4 SiPMs for direct detection of liquid argon scintillation light at cryogenic temperatures, demonstrating their photon detection efficiency without wavelength shifting.

Contribution

It provides the first detailed characterization of VUV4 SiPMs' performance in liquid argon, including direct sensitivity and efficiency measurements at cryogenic conditions.

Findings

Photon detection efficiencies of 14.7% and 17.2% at 128 nm.

Successful operation of VUV4 SiPMs inside liquid argon without wavelength shifting.

Cryogenic performance data for VUV4 SiPMs in liquid argon.

Abstract

Detection of light signals is crucial to a wide range of particle detectors. In particular, efficient detection of vacuum ultraviolet (VUV) light will provide new opportunities for some novel detectors currently being developed, but is technically challenging. In this article, we characterized the performance of Hamamatsu VUV4 silicon photomultipliers (SiPMs) for detecting VUV argon scintillation light without wavelength shifting. Using a customized cryogenic amplifier design, we operated two models of VUV4 SiPMs inside liquid argon and thoroughly examined their direct sensitivities to liquid argon scintillation. In addition to describing their cryogenic performance, we measured a photon detection efficiency of $14.7^{+1.1}_{-2.4}$% and $17.2^{+1.6}_{-3.0}$% at 128 nm for these two VUV4 models for operation at 4 V of overvoltage, with the main uncertainty arising from the SiPM reflectivity for VUV light.