Thick GEM-based detectors of single photons for Cherenkov imaging applications

Photon detectors based on micropattern gas detectors represent a new generation of gaseous photon detectors. In the context of a project to upgrade the gas photon detectors of COMPASS RICH-I, we are performing an R&D programme aimed both to establish the principles and to develop the engineering aspects of photon detectors based on multi-layer arrangements of thick GEMs electron multipliers coupled to a CsI photoconverter. The major results of a four-year R&D study are recalled with emphasis to the most recent achievements.