Speaker
Description
Distributed silicon photomultiplier (SiPM) arrays provide a compact photosensor architecture for liquid scintillator detectors, but the temperature dependence of SiPMs immersed directly in the scintillation medium remains poorly characterized. We studied a 125-liter linear-alkylbenzene-based liquid scintillator detector read out by 125 immersed SiPM channels from room temperature to −30 °C. Cosmic-ray muons were used to evaluate the sensor and detector responses. Cooling from +15 °C to −30 °C reduced the per-channel dark-count rate by a factor of about 13, increased the single-photoelectron response by 49%, and increased the muon light yield by 17%. Improved photoelectron separation and baseline stability also enabled stopping-muon selection, yielding an effective muon lifetime of 1992 ± 134 ns, consistent with the expected value for a hydrocarbon scintillator after accounting for μ− capture on carbon. These results demonstrate stable low-temperature operation of immersed SiPM arrays.