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Description
Near Ultraviolet, High Density (NUV-HD) SiPM technology, developed at FBK (Trento, Italy), is based on a p-on-n junction and features peak photon-detection efficiency (PDE) in excess of 60% at 410 nm. Dark Count Rate (DCR) is in the order of 100 kHz/mm2, correlated noise is 10% at 55% PDE and microcell pitch ranges between 15 um and 40 um. Sensitivity remains high down to 320 nm, with a PDE of 48% (including package).
Single Photon Timing Resolution (SPTR) of NUV-HD SiPMs was below 30 ps FWHM, when measured on single SPAD with covered edges, and increased to 75 and 180 ps FWHM for SiPMs with active areas of 1x1 mm2 and 3x3 mm2, respectively, because of the electronic noise. NUV-HD SiPMs provide state-of-the art 85 ps FWHM coincidence resolving time (CRT) in PET applications, reading out the light of a Ca co-doped LYSO crystal.
Recent interest in the SiPM readout of liquid scintillators (mainly LAr and LXe) triggered the development of a cryogenic variant of the NUV-HD technology (NUV-HD-Cryo), which is optimized for operation at cryogenic temperatures and features a DCR of a few mHz/mm2 at 77 K. At this temperature, few-photon counting capability was demonstrated, with S/N larger than 14, using a 24 cm2 SiPM array coupled to a single analog readout channel. Ongoing optimizations include the development of devices with extended deep-UV sensitivity: preliminary results show a PDE of 20 % at 178 nm.
