Study of combined THGEM/GAPD-matrix multiplier in a two-phase Cryogenic Avalanche Detector in Ar

Two-phase Cryogenic Avalanche Detectors (CRADs) with combined THGEM/GAPD-matrix multiplier have become an emerging technique in rare-event experiments such as those of coherent neutrino-nucleus scattering and dark matter search. In this work we continue to study the performance of the two-phase CRAD in Ar with THGEM/GAPD-matrix charge/optical readout. The matrix was composed of a 3×3 array of GAPDs (Geiger-mode APDs), optically recording THGEM-hole avalanches in the Near Infrared (NIR). Gain, time, amplitude and spatial resolution properties of the combined multiplier are described.