COMPASS is a fixed target experiment at CERN SPS aimed to study HadronStructure and Spectroscopy. Hadron Identification in the momentum range between3 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 ofCOMPASS, RICH-1 have been upgraded by replacing four MWPCs based photondetectors with newly developed MPGD based photon detectors. The architecture ofthe novel detectors is a hybrid combination of two layers of THGEMs and aMicroMegas. The top of the first THGEM is coated with CsI acting as areflective photo-cathode. The anode is segmented in pads capacitively coupledto the APV-25 based readout. The new hybrid detectors have been commissionedduring 2016 COMPASS data taking and stably operated during 2017 run. In thispaper all aspects of the novel photon detectors for COMPASS RICH-1 arediscussed.
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