Single photon detection with SiPMs irradiated up to 10$^{14}$ cm$^{-2}$ 1-MeV-equivalent neutron fluence

TL;DR

This study investigates the effects of high neutron irradiation on silicon photomultipliers (SiPMs), demonstrating that annealing and cryogenic operation enable single photon detection even after exposure to fluences up to 10^14 cm^-2.

Contribution

The paper shows that annealing and cryogenic temperatures can restore SiPM performance after extreme neutron irradiation, extending their usability in high-radiation environments.

Findings

Annealing at high temperature improves SiPM performance post-irradiation.

Cryogenic operation reduces dark count rate below 1 kHz after high fluence exposure.

Single photon detection remains feasible after irradiation up to 10^14 cm^-2 with proper treatment.

Abstract

Silicon photomultipliers (SiPM) are solid state light detectors with sensitivity to single photons. Their use in high energy physics experiments, and in particular in ring imaging Cherenkov (RICH) detectors, is hindered by their poor tolerance to radiation. At room temperature the large increase in dark count rate makes single photon detection practically impossible already at 10$^{11}$ cm$^{-2}$ 1-MeV-equivalent neutron fluence. The neutron fluences foreseen by many subdetectors to be operated at the high luminosity LHC range up to 10$^{14}$ cm$^{-2}$ 1-MeV-equivalent. In this paper we present the effects of such high neutron fluences on Hamamatsu and SensL SiPMs of different cell size. The advantage of annealing at high temperature (up to 175 $^{\circ}$C) is discussed. We demonstrate that, after annealing, operation at the single photon level with a SiPM irradiated up to 10$^{14}$ cm$^{-2}$ 1-MeV-equivalent neutron fluence is possible at cryogenic temperature (77 K) with a dark count rate below 1~kHz.