NEXT-100 Technical Design Report (TDR). Executive summary

Abstract

In this Technical Design Report (TDR) we describe the NEXT-100 detector that\nwill search for neutrinoless double beta decay (bbonu) in Xe-136 at the\nLaboratorio Subterraneo de Canfranc (LSC), in Spain. The document formalizes\nthe design presented in our Conceptual Design Report (CDR): an\nelectroluminescence time projection chamber, with separate readout planes for\ncalorimetry and tracking, located, respectively, behind cathode and anode. The\ndetector is designed to hold a maximum of about 150 kg of xenon at 15 bar, or\n100 kg at 10 bar. This option builds in the capability to increase the total\nisotope mass by 50% while keeping the operating pressure at a manageable level.\n The readout plane performing the energy measurement is composed of Hamamatsu\nR11410-10 photomultipliers, specially designed for operation in low-background,\nxenon-based detectors. Each individual PMT will be isolated from the gas by an\nindividual, pressure resistant enclosure and will be coupled to the sensitive\nvolume through a sapphire window. The tracking plane consists in an array of\nHamamatsu S10362-11-050P MPPCs used as tracking pixels. They will be arranged\nin square boards holding 64 sensors (8 times8) with a 1-cm pitch. The inner\nwalls of the TPC, the sapphire windows and the boards holding the MPPCs will be\ncoated with tetraphenyl butadiene (TPB), a wavelength shifter, to improve the\nlight collection.\n