Development of compact micro-pattern gaseous detectors for the CEPC digital hadron calorimeter

Résumé fourni par la source

An imaging hadron calorimeter with digital readout (DHCAL) using the micro-pattern gaseous detector (MPGD) technology is one of the hadron calorimeter options for the Circular Electron Positron Collider (CEPC). The sensitive detector of the CEPC DHCAL is required to be compact and highly efficient for MIPs with low hit multiplicity. A double-GEM detector and a resistive WELL (RWELL) detector based on the THGEM technique have been investigated as options for the DHCAL sensitive detector. A 030 cm × 3 cm double-GEM prototype with "3 mm-1 mm-1 mm" structure was built with the self-stretching technique to study the performance of the double-GEM detector for application to the CEPC DHCAL. The double-GEM prototype was read out with the MICROROC chip and tested with cosmic-rays. The results of the test show a detection efficiency higher than 95% and a hit multiplicity of 1.2. Compared with the GEM detector, the RWELL detector is advantageous in minimizing the dead area due to its simple assembly without stretching. In addition, it has a more compact structure than the double-GEM detector thanks to its single-stage gas amplification without any induction gap. A 25 cm × 25 cm RWELL prototype with a resistivie DLC electrode was developed by using the thermal bonding technique. And a fast grounding circuit was designed on its anode PCB to enhance the rate capability of the detector. Preliminary results from tests of the RWELL prototype with X-rays show that the detector could operate at a gain of 0∼800 with a 0∼2% uniformity, maintain such a gain when irradiated with 8 keV X-rays at a rate of 0∼30 kHz/cm 2 . Based on these results, the RWELL detector promises to be a good candidate as the sensitive detector of the CEPC DHCAL, which merits further studies.

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