Visible light photon counters and the Dط scintillating fiber tracker

The Visible Light Photon Counter (VLPC) will be used as the photodetector for a large-scale scintillating fiber tracker in the Dط upgrade. The VLPC is a solid-state device capable of high-rate single photon counting with excellent quantum efficiency, low noise and small gain dispersion. The development of the VLPC through several versions will be discussed, including the results of the characterization of more than 4278 channels of version HISTE-IV. Results of a cosmic ray test of a 3072 channel fiber tracking prototype read out with HISTE-IV VLPCs will be presented, including measurements of position resolution, tracking efficiency, and stability of VLPC performance over many months of operation. Finally, preliminary results from tests of the latest version of VLPCs and a discussion of their implementation in the Dط tracker will be given.