Readout of Large Capacitance SiPMs by Weak Coupling to Charge Sensitive Amplifier

Abstract

Large area and large capacitance silicon photomultiplier (SiPM) arrays are employed to collect scintillation light in noble liquid time projection chambers (TPC) such as DarkSide, nEXO, MEGII, protoDUNE and DUNE. Light readout using ASICs designed for operation in noble liquids is a solution for large meter-scale photon detectors. However, conventional readout requires a high voltage decoupling capacitor larger than SiPM capacitance (in the range of tens of nF) to achieve full charge transfer to the preamplifier. Here, we demonstrate a readout concept by weakly coupling (via a capacitor lower by an order of magnitude than SiPM capacitance) to a charge sensitive amplifier, LArASIC in this case, without any loss in the signal to noise ratio (S/N). The single-photoelectron detection, signal-to-noise ratio, timing resolution, and coincidence detection are experimentally characterized.