R&D for the charge readout of the nEXO experiment

The nEXO experiment searches for neutrinoless double beta decay using a 5-tonne scale LXe time projection chamber enriched to 90% in Xe136, reaching a half-life sensitivity greater than 10²⁸ years. We outline several efforts pursued by the Stanford group; amongst other, the testing of a cryogenic application specific integrated circuit (ASIC) for the charge readout, a solution chosen to meet the stringent noise and radioactivity requirements, and to reduce the system complexity improving measurement fidelity with respect to room temperature solutions. Prototypes of the nEXO charge-readout module readout with an ASIC readout system, developed by SLAC, are being tested in a LXe TPC. Additionally, a larger TPC is under construction able  to accommodate a 4 tile charge readout module, investigate cross-talk between the tiles and its impact on the energy resolution