Contributions of Cherenkov Light to the Signals from Lead Tungstate Crystals

Results are presented of detailed measurements of the signals generated by high-energy electrons and muons in lead tungstate crystals. A significant fraction of the light produced in these crystals and detected by photomultiplier tubes is the result of the Čerenkov mechanism. This is concluded from the angular dependence of the signals and from their time structure. Depending on the orientation of the crystals and on the particle type, Čerenkov light may account for up to 15% of the total signals.