Speaker
Description
Liquid xenon (LXe) based detectors are a leading technology for low-background searches, including dark matter and neutrinoless double beta decay detection. Improving the sensitivity of next-generation experiments requires further reduction of radioactive backgrounds from detector components, motivating silicon photomultipliers (SiPMs) as a leading candidate to replace widely used photomultiplier tubes (PMTs).
The Light Only Liquid Xenon (LoLX) Collaboration operates an upgraded small-scale detector (LoLX 2) at McGill University with a ~ 5 kg LXe target. The detector is designed to study scintillation properties of LXe and the production of Cherenkov radiation. Instrumented with a total of 80 SiPMs from two manufacturers, Hamamatsu and Fondazione Bruno Kessler, LoLX 2 also allows for the direct in situ comparison of photosensor performance in identical experimental conditions, using a vacuum-ultraviolet PMT for reference.
This talk will present the results of the first experimental run of LoLX 2, including a comparison of the relative photon detection efficiency (PDE) and operational characteristics of the photosensors using laser calibrations and external gamma sources, highlighting a significant discrepancy of 33–38% in PDE for the Hamamatsu VUV-4 compared to PDE models from vacuum measurements. Supported by a comprehensive Monte Carlo simulation that includes photon transport and a detailed SiPM optical model, we resolved the discrepancy with an angular and wavelength-dependent PDE model incorporating surface shadowing effects. Prospects for the next upgrade of the system will briefly be discussed, including improved electronics for signal readout, the deployment of an internal radiation source, and the implementation of an online xenon purification system.
| Keyword-1 | Liquid Xenon |
|---|---|
| Keyword-2 | Silicon Photomultiplier |
| Keyword-3 | Scintillation |