1. A method for controlling voltage applied to a photomultiplier used in a scintillation counter radiation detector, comprising: determining numbers of voltage pulses having each of a plurality of predetermined amplitudes generated by the photomultiplier in response to radiation events being imparted to a scintillation detector; conducting the numbers of voltage pulses at each of the predetermined amplitudes to a trained artificial neural network; and causing the artificial neural network to generate a signal corresponding to an amount of adjustment to the voltage applied to the photomultiplier.