Development of pixel hybrid photon detectors for the RICH counters of LHCb

The particle identification system proposed for the LHCb experiment is based on RICH counters with three different radiator materials and hybrid photon detectors (HPDs) as a possible readout. Within this framework, one approach to HPD design is the "pixel-HPD". This is based on standard image intensifier geometries that strongly focus the photoelectrons onto a silicon pixel array, bump-bonded to a binary readout chip with matching pixel electronics. This paper reports on the ongoing developments in this field and in particular on the first operation of a 40:11 mm pixel-HPD prototype tube.1