# The Hybrid MPGD-based photon detectors of COMPASS RICH-1

## TL;DR

This paper presents the development, construction, and performance evaluation of novel hybrid gaseous photon detectors used in the COMPASS RICH-1 experiment, achieving high efficiency and resolution for single photon detection.

## Contribution

The paper introduces a new hybrid MPGD-based photon detector architecture combining THGEM and Micromegas technologies for RICH applications.

## Key findings

- Stable operation over 1.4 m² area
- Single photon angular resolution of ~1.8 mrad
- Detection of about 10 photons per ring at saturation

## Abstract

Novel gaseous detectors of single photons for RICH applications have been developed and installed on COMPASS RICH-1 in 2016. They have a hybrid architecture consisting of two staggered THGEM layers (one equipped with a CsI photoconverting layer) and a bulk Micromegas; they cover a total area of 1.4 squared meters and operate stably and efficiently. They provide a single photon angular resolution of ~ 1.8 mrad and about 10 detected photons per ring at saturation. The main aspects of their construction and commissioning, their characterization and performance figures are presented.