Development of low background PMT R13111

Abstract

Photomultiplier tubes (PMTs) are one of the largest background sources for many direct dark matter search experiments. The development of a new low background PMT, Hamamatsu R13111, for liquid xenon dark matter experiments is ongoing. With its 3-inch-wide convex protruding photocathode, the R13111 achieved a large reduction in radioactive impurity compared to its precursor, the R10789, which was used in the XMASS-I detector. Xenon leaks, a problem reported by the XENON1T and PandaX experiments, are also investigated to realize stable operation with liquid xenon.