The LHCb RICH photon detector system

The LHCb experiment at the CERN Large Hadron Collider will employ two Ring Imaging Cherenkov (RICH) detectors for particle identification. The Cherenkov photons will be detected by planes of photon detectors covering a total active surface area of 2.1 m2. The detector chosen for this task is the pixel hybrid photon detector (HPD). This combines silicon pixel sensors, integrated electronics and high-density interconnects together with vacuum-tube technology to produce an efficient, low-noise detector sensitive to single photons. For the complete photon detector system of the LHCb RICH, 484 such HPDs are required and these have been fully integrated into detector modules. Specific aspects of this integration within the RICH system are described together with the steps taken to ensure the efficiency and reliability of the detector in the harsh environment of LHCb.