Speaker
Description
Photomultiplier tubes (PMTs) are often used in low-background particle physics experiments, which rely on an excellent response to single-photon signals and stable long-term operation. In particular, the Hamamatsu R11410 model is the light sensor of choice for many detectors utilising xenon as target material. In the past, this PMT model has shown issues affecting its long-term operation, including light emission and the degradation of the PMT vacuum through small leaks, which can lead to spurious signals known as afterpulses. In this talk, we present an improved PMT testing procedure that includes newly developed tests targeted at the detection of intermittent light emission as well as vacuum degradation. The use of both new and upgraded facilities allowed us to test in total 368 new PMTs for the XENONnT detector in a cryogenic xenon environment. We exclude the use of 26 of the 368 tested PMTs and categorise the remainder according to their performance. Given that we have improved the testing procedure compared to XENON1T, yet we rejected fewer PMTs, we expect significantly better PMT performance in XENONnT.
