System test of a three-column LHCb RICH-2 prototype detector

Abstract A three-column prototype of the downstream LHCb Ring Imaging Cherenkov detector (RICH-2) has been constructed. The prototype module contains six 8 cm diameter Hybrid Photon Detectors (HPDs), mounted in a close-packed arrangement, and read out at the full LHC speed of 40 MHz. Pairs of HPDs are read out with LHCb prototype on-detector RICH electronics utilizing radiation-tolerant FPGA technology, optical links and 40 MHz trigger-timing and control (TTC). The columns have a modularized mechanical arrangement with compact high- and low-voltage distribution systems. A full system test of the readout has been verified. The three-column structure has been mounted in a Cherenkov vessel and Cherenkov rings have been observed from N 2 and C 4 F 10 gas radiators in a CERN pion test beam.