SiPMs coated with TPB: coating protocol and characterization for NEXT

Abstract

Silicon photomultipliers (SiPM) are the photon detectors chosen for the\ntracking readout in NEXT, a neutrinoless {\\beta}{\\beta} decay experiment which\nuses a high pressure gaseous xenon time projection chamber (TPC). The\nreconstruction of event track and topology in this gaseous detector is a key\nhandle for background rejection. Among the commercially available sensors that\ncan be used for tracking, SiPMs offer important advantages, mainly high gain,\nruggedness, cost-effectiveness and radio-purity. Their main drawback, however,\nis their non sensitivity in the emission spectrum of the xenon scintillation\n(peak at 175 nm). This is overcome by coating these sensors with the organic\nwavelength shifter tetraphenyl butadienne (TPB). In this paper we describe the\nprotocol developed for coating the SiPMs with TPB and the measurements\nperformed for characterizing the coatings as well as the performance of the\ncoated sensors in the UV-VUV range.\n