AI Insight
This study directly compared two types of Silicon Photomultipliers (SiPMs) - FBK VUV-HD3 and HPK VUV4 - operating in liquid xenon to detect vacuum-ultraviolet light for rare-event physics experiments. The researchers found that HPK SiPMs detected 33-38% less light than FBK devices, a larger discrepancy than expected from standard models. The difference was explained by incorporating surface shadowing effects into optical simulations, which then accurately matched experimental observations.
Why it matters
These findings will directly inform the design and photosensor selection for next-generation dark matter and neutrino experiments that rely on liquid xenon detectors, potentially affecting the sensitivity and cost-effectiveness of multi-million dollar research facilities.
Understand the Science
Abstract: Silicon Photomultipliers (SiPMs) are a critical technology for the next generation of rare-event search experiments using liquid xenon (LXe). LXe scintillation is emitted primarily in the vacuum-ultraviolet (VUV), requiring photosensors with high VUV detection efficiency under cryogenic operating conditions. Direct characterization of VUV-sensitive SiPMs in LXe is therefore important for informing detector design and comparing device response. This work presents a direct comparison of Fondazione Bruno Kessler (FBK) VUV-HD3 and Hamamatsu (HPK) VUV4 SiPMs operated simultaneously within the Light-only Liquid Xenon (LoLX) detector. Using data collected with gamma sources placed outside the detector, we characterized the relative performance of these photosensors. Our analysis reveals that under these operating conditions, the HPK SiPMs observe 33-38% less light than the FBK devices, a larger difference than predicted by standard PDE models in vacuum measurements. We show that this discrepancy is resolved by an angular and wavelength dependent PDE model incorporating surface shadowing effects into our optical simulation, which then accurately reproduces the experimental data. This finding has significant implications for the selection and implementation of photosensors in future large-scale LXe detectors.
Source: Performance of FBK VUV-HD3 and HPK VUV4 SiPMs in the Light-only Liquid Xenon (LoLX) Detector