Novel resistive charge-multipliers for dual-phase LAr-TPCs: towards stable operation at higher gains

Cryogenic versions of Resistive WELL (RWELL) and Resistive Plate WELL (RPWELL) detectors have been developed, aimed at stable avalanche multiplication of ionization electrons in the vapor phase of LAr (dual-phase TPC). In the RWELL, a thin resistive DLC layer deposited on top of an insulator is inserted in between the electron multiplier (THGEM) and the readout anode; in the RPWELL, a resistive ferrite plate is directly coupled to the THGEM. Radiation-induced ionization electrons in the liquid are extracted into the gaseous phase. They drift into the THGEM's holes where they undergo charge multiplication. Embedding resistive materials into the multiplier proved to enhance operation stability due to the mitigation of electrical discharges — thus allowing operation at higher charge gain compared to standard THGEM (a.k.a. LEM) multipliers. We present the detector concepts and report on the main preliminary results.