MPGD-based photon detectors for the upgrade of COMPASS RICH-1 and beyond

TL;DR

This paper presents the development, construction, and successful deployment of hybrid MPGD-based photon detectors in the upgraded RICH-1 detector at CERN's COMPASS experiment, enhancing hadron identification capabilities.

Contribution

Introduction of a novel hybrid MPGD-based photon detector architecture for RICH-1, combining THGEMs and Micromegas, with successful commissioning and stable operation during data taking.

Findings

Detectors achieved stable operation during 2017 data run.

Hybrid design improved photon detection efficiency.

Successful integration into the existing RICH-1 system.

Abstract

COMPASS is a fixed target experiment at CERN SPS aimed to study hadron structure and spectroscopy. Hadron identification in the momentum range between $3$ and $55 GeV/c$ is provided by a large gaseous Ring Imaging Cherenkov Counter, RICH-1. To cope with the challenges imposed by the new physics program of COMPASS, RICH-1 has been upgraded by replacing four MWPC-based photon detectors with newly developed MPGD-based photon detectors. The architecture of the novel detectors is a hybrid combination of two layers of THGEMs and a Micromegas. The top of the first THGEM is coated with CsI acting as a reflective photo-cathode. The anode is segmented in pads capacitively coupled to the APV-25 based readout. The new hybrid detectors have been commissioned during the 2016 COMPASS data taking and stably operated during the 2017 run. In this paper design, construction, operation and performance aspects of the novel photon detectors for COMPASS RICH-1 are discussed.