The Hpw Proton Decay Experiment

The Harvard-Purdue-Wisconsin water Cherenkow proton-decay detector is described. Running through early August, 1983, comprises 3.1 x 10/sup 6/ triggers at a 0.6 Hz rate, and 3.6 x 10/sup 6/ triggers at 0.7 Hz. Track reconstruction is demonstrated for cosmic-ray muons. The apparatus records full data for as many as 7 delayed triggers occuring within 32 microseconds of the primary trigger or each other. Such delayed triggers have been used to calibrate the detector on electron-decays of muons. We discuss the implications of delayed triggers for rapid recognition of certain classes of candidates for nucleon decay, and indicate the present sensitivity of the experiment.