Characterization and performance of visible light photon counters (VLPCs) for the upgraded DØ detector at the Fermilab Tevatron

Abstract The upgraded DO detector at the Tevatron collider will use about 100 000 pixels of Visible Light Photon Counters (VLPCs) readout for its scintillating fiber tracker and preshower detectors. VLPCs are solid state photodetectors that are operated at the temperature of a few degrees Kelvin, capable of detecting single photons. All VLPC chips were characterized in the presence of a 20 MHz background of photoelectrons. The acceptance rate was 87%. The operating bias ranges from 5.8 to 8.0 V, the gain from 20 000 to 60 000, and the threshold from 5 to 15 fC. All 8 pixels belonging to one chip have very similar efficiencies, thresholds and gains.