Separation of cosmic-ray components in a single water Cherenkov detector

We describe the use of a water Cherenkov detector to study in detail the signals associated to secondary cosmic rays. In particular we describe a direct way to identify some of the components of secondary cosmic rays. It consists of a polyethylene tank of 1.54 m of diameter filled with water up to a height of 1.2 with one 8″ phototube looking downwards in the center of the tank at the level of the water. By collecting data using three different types of triggers, namely, vertical non-central muons, vertical central muons and arbitrary muons, we show the existence of very strong correlations among the voltage amplitudes, charge depositions, and rise times from 10% to 90% for isolated electrons, isolated muons and extended air showers using a single detector. The simple technique described also allows a clear identification of the muon interaction with the PMT glass envelope. We discuss a way in which our results can be used, in conjunction with a classification scheme such as neural networks, to form artificial signals for extensive air showers with the purpose to estimate the muon/EM ratio of air showers measured with large ground arrays of water Cherenkov detectors such as in the case of the Pierre Auger Observatory.