Laboratory studies of THGEM-based WELL structures with resistive anode

In this work we investigate three variants of single amplification-stage detector elements; they comprise THGEM electrodes closed at their bottom with metallic or resistive anodes to form WELL-type configurations. We present the results of a comparative study of the Thick-WELL (THWELL), Resistive-WELL (RWELL) and Segmented Resistive WELL (SRWELL) focusing on their performance in terms of spark-quenching capability, gain variation with position and counting rate, pulse shapes and signal propagation to neighboring readout pads; the study included both 30 × 30 and 100 × 100 mm² detectors. It was shown that the WELL structures with resistive anodes offer stable operation even in a highly ionizing environment with effective spark quenching, as well as higher gain than the standard THGEM/inductiongap configuration. Cross talk between neighboring readout pads (here 10 × 10 mm² in size) was shown to be effectively eliminated in the segmented detector with a conductive grid underneath the resistive layer. The latter multiplier should allow for the design of very thin detectors, e.g. sampling elements in digital hadronic calorimeters planned for experiments in future linear colliders.