Modeling and Simulation of the R5912 Photomultiplier for the LAGO Project

We present the results of the Hamamatsu R5912 photomultiplier tube modelling and simulating. The model can be adapted to any photomultiplier architecture by changing the number of electrodes, voltage distribution, and intrinsic PMT parameters. Our approach solves the use of tapered voltage dividers and allows photomultiplier simulations under stimulation conditions. The model implementation is not limited to SPICE-based software but also be used with compiled and interpreted programming languages. The modeled pulse charge of a vertical muon differs about 4% from the data. The resistive divider model tested reproduces the voltage distribution along the dynodes with a variance of ~3.5%. We compare the photomultiplier model linearity with the data from the operating LAGO's (Latin American Giant Observatory) water Cherenkov detectors installed at Bucaramanga-Colombia and Bariloche-Argentina.