Characterizing CRYO ASIC and Charge Readout in nEXO

Neutrinoless double beta decay (0vbb) is a lepton-number-violating nuclear transition forbidden in the Standard Model. The observation of 0vbb would fundamentally imply that neutrinos are their own anti-particles, indicating their Majorana nature and might explain the asymmetry of matter and anti-matter in the universe. nEXO is a proposed next-generation 0vbb experiment with 5000 kg of isotopically enriched liquid xenon (LXe) in a time projection chamber (TPC). Ionization charge produced by ionizing particles drifts along the electric field towards the anode where it is read out by arrays of crossed strips, deposited on 10 cm*10 cmdielectric tiles. The signal pre-processing, digitization and read-out steps are carried out at cryogenic temperatures by a follow-up novel System-on-Chip CRYO ASIC deployed on the back side of the tiles. nEXO requires a high precision of reconstruction of the electron pair’s energy to effectively discriminate signals from backgrounds. In this study, we focus on tests at SLAC and Stanford to characterize the CRYO ASIC, along and combined with charge readout tiles, and understand noise and signal reconstruction properties necessary to elucidate the charge reconstruction and physical potentials of nEXO.