  We present the results of modeling and simulating the Hamamatsu R5912
photomultiplier tube that is used in most of the sites of the Latin American
Giant Observatory (LAGO). The model was compared with data of in-operation
water Cherenkov detectors (WCD) installed at Bucaramanga-Colombia and
Bariloche-Argentina. The LAGO project is an international experiment that spans
across Latin America at different altitudes joining more than 35 institutions
of 11 countries. It is mainly oriented to basic research on gamma-ray bursts
and space weather phenomena. The LAGO network consists of single or small
arrays of WCDs composed mainly by a photomultiplier tube and a readout
electronics that acquires single-particle or extensive air shower events
triggered by the interaction of cosmic rays with the Earth atmosphere.
