In-Situ Performance of FBK VUV-HD3 and HPK VUV4 SiPMs in the LoLX Liquid Xenon Detector
This paper presents a direct in-situ comparison of FBK VUV-HD3 and HPK VUV4 SiPMs within the LoLX liquid xenon detector, revealing that HPK devices detect 33–38% less light than FBK devices under operating conditions and demonstrating that this discrepancy is resolved by an optical simulation incorporating angular and wavelength-dependent surface shadowing effects.