Observation of light emission from Hamamatsu R11410-20 photomultiplier tubes

TL;DR

This study demonstrates that Hamamatsu R11410-20 photomultiplier tubes emit single photons when biased at high voltage, even with high dark count rates, which is crucial for experiments detecting rare events in liquid xenon detectors.

Contribution

First observation of photon emission from R11410-20 PMTs under high voltage bias at various temperatures, highlighting a potential background in rare event searches.

Findings

Photomultiplier tubes emit single photons at high voltage bias.

Emission observed at room temperature and down to -60°C.

Implication for background considerations in liquid xenon detectors.

Abstract

We have shown that high voltage biased Hamamatsu R11410-20 photomultipliers with a dark count rate above 10 kHz emit single photons. The effect has been observed in a few units at room temperature and temperatures reduced down to -60 degrees Celsius. The effect should be taken into account in experiments aimed on search for rare events with small energy depositions in massive liquid xenon detectors.