CRYO: A System-on-Chip for Charge Readout in the nEXO Experiment

CRYO is a charge read-out ASIC aimed for noble liquid Time Projection Chamber (TPC) experiments. It implements a system-on-chip (SoC) architecture with minimal number of I/Os making it an attractive solution for neutrino experiments such as DUNE (far detector) and nEXO. Two different variants of CRYO ASIC have been designed to meet the requirements of the experiments. The version for DUNE has been reported previously by immersing the ASIC in LN2 to be close to LAr temperature (i.e., 87 K). This contribution, on the other hand, focuses on the test and characterization of the nEXO variant, an improved version optimized to operate at 160 K and with the front-end (FE) section tailored for the equivalent capacitance of the LXe detector (i.e., 40 pF). The small size of the ASIC (7 mm x 9 mm) and the absence of packaging bring an additional benefit in terms of radioactivity load, which is a critical requirement in nEXO for rare events such as neutrinoless double beta (0 νββ) decay. Similar to the DUNE version, the nEXO variant is fabricated in a 130 nm CMOS process and works with a single supply voltage. We present preliminary results obtained in cold gas using LN2 to emulate the LXe environment (i.e., 160 K).