Cristiano GALBIATI - Princeton University, USA

The existence of dark matter in the Universe is now established by a variety of cosmological observation and it represents the first evidence of new physics beyond the Standard Model of particle physics.  Observation of dark matter particles in low background detectors operating in the cosmic silence of underground laboratories would open a door on a new sector of physics, but this has required  the development of new solid state photodetectors with an outstanding photon counting ability.  The advanced nanofabrication techniques available in the nanoelectronic fabs make now possible their mass production. The DarkSide program of dark matter detectors at Laboratori Nazionali del Gran Sasso (LNGS) relies on two-phase argon Time Projection Chambers (TPCs), installed at the center of two nested veto detectors.  Its DarkSide-50 detector, currently in operation, is the only noble liquid dark matter detector operating in a background-free mode.  The primary method for sensing of particles is detection of VUV argon scintillation light (128 nm) wavelength-shifted in the blue region (~430 nm).  An improvement to the sensitivity of the program depends critically on the development of Silicon Photomultipliers (SiPMs) photosensors operating at the cryogenic temperature of 87 Kelvin.  SiPMs would replace traditional PhotoMultiplier Tubes (PMTs), permitting to reduce the radioactive background of the detector and to significantly enhance the yield of detected scintillation light detected.  A new detector of the DarkSide program will utilize SiPMs designed by FBK, mass produced by LFoundry. Success in the development of SiPMs would make of DarkSide-20k the highest sensitivity detector in the world in the search for dark matter and could make its direct observation possible.  The SiPMs developed for DarkSide will also find possibile applications in other field, from medicine to bio-molecular imaging.

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