Lior Arazi (Weizmann Institute of Science)
Thick Gas Electron Multipliers (THGEMs) have the potential of constituting robust sampling elements in Digital Hadron Calorimetry (DHCAL), in future HEP Colliders like the ILC. We report on the properties of novel, most promising single- and double-THGEM structures, with multipliers mounted in a WELL configuration on top a segmented resistive layer coupled to readout pads; the overall thickness of the detector is about 5 mm (excluding the electronics). A 10x10 cm2 prototype, with 1 cm2 pads and APV-SRS readout, was very recently investigated in muon and pion beams, studying several multiplier configurations. Full efficiency, as high as 98%, was demonstrated with average pad-multiplicity as low as 1.1. The local efficiency and multiplicity values across the pad surface are provided as well. The use of the resistive anode resulted in a dramatic decrease in discharge magnitude, with typical potential drops of only a few volts; such micro-discharges occurred with probabilities of the order of 10^-6 for muons and 10^-5 for pions, in rates as high as a few kHz/cm2. The detector operated stably throughout the run, with no observable gain shifts and nearly no disruption of data acquisition. Further optimization work and research on larger detectors are underway.
Adam Yigal Rubin (Weizmann Institute of Science (IL)) Amos Breskin (Weizmann Institute of Science (IL)) Carlos Azevedo (University of Aveiro) Eraldo Oliveri (Sezione di Pisa (IT)) Hugo Natal da Luz (University of Coimbra) Joao F.C.A. Veloso (Uni Aveiro) Joaquim dos Santos (University of Coimbra) L Moleri (Weimann Institute) Lior Arazi (Weizmann Institute of Science) Michael Pitt (Weizmann Instetute of Science)