A scintillating fiber tracker with high time resolution for high-rate experiments

A fast and precise scintillating fiber (SciFi) tracker, using 0.5-mm-diameter fibers (Kuraray SCSF-78MJ) and position-sensitive photomultiplier tubes (Hamamatsu H6568), has been developed for the COMPASS (NA58) experiment at CERN. Tests of a 16-channel prototype showed an excellent stability in time resolution, in spatial resolution, as well as in detection efficiency under different beam flux of up to 1.4 /spl times/ 10/sup 8/ muons/spill. Four SciFi tracker stations have been constructed and all of them are presently under operation in the experiment with high performances as expected from the prototype.