Extended High Temperature Exposure of a Silicon Photomultiplier for the nEXO Neutrinoless Double Beta Decay Experiment

The Pocar Lab located at UMass Amherst is one of many labs working with the next-Enriched Xenon Observatory (nEXO) collaboration, assisting in the pursuit of detecting neutrinoless double beta decay in Xenon-136. We report on the effects of an accidental baking of the Pocar lab's Liquid Xenon cell, subjecting a Hamamatsu VUV4 Silicon Photomultiplier (SiPM) to elevated temperatures of 460 Kelvin for a duration of approximately 2.5 days. Producing ratios of comparable SiPM signal amplitude data from before and after the event, we find an increase in the Photon Detection Efficiency (PDE) of the SiPM, ranging from 25 to 30 percent. A comparison of current-voltage (IV) curve plots in the same manner indicate little to no internal damage to the SiPM. We postulate that the PDE boost could be attributed to the high temperatures helping remove potential debris on the surface of the SiPM, citing a study done by Hamamatsu.