First large sample study of visible light photon counters (VLPC's)

Characterization of a large number of visible light photon counters (VLPC) is an integral part of the scintillating fiber system test for the DO upgrade, currently underway at Fermilab. We report results from our investigation of 4200 channels of HISTE IV VLPC's, for use in a cosmic ray test. We have studied the dependence of critical device characteristics like quantum efficiency, gain, and noise as a function of operating temperature and VLPC bias voltage, and the variation of these characteristics over the large sample. We also discuss the general operation of the devices and the problems encountered during the characterization.