PERFORMANCE OF A LARGE-SCALE SCINTILLATING-FIBER TRACKER USING VLPC READOUT

We report on results of a cosmic ray test of a scintillating fiber tra cker using Visible Light Photon Counter (VLPC) readout. Two different detector configurations have been constructed and operated, the first with a total of 3,072 channels and the second with 1,785 channels. The 3,072 channel system is a prototype for the D0 detector tracking upgr ade and represents a configuration that is similar to that in the fina l detector. The second, smaller test was specifically designed to stud y the position resolution capabilities of the fiber tracker. A descrip tion of the cosmic ray test including trigger, fiber configuration, un doped lightguides, VLPC cassettes and cryogenics, and calibration syst em is given. Final results from the 3,072 channel test will be present ed, including measurements of resolution, light yield per minimum ioni zing particle, singlet and doublet efficiency, and long-term stability . Resolution results from the second, 1,785 channel test will be compa red to the predicted resolution from Monte Carlo studies.