Fast gain calibration of photomultiplier and electronics

We report on a fast method for calibration of the gain of photomultiplier tubes and associated electronics. The gain was determined by the analysis of fluctuations of the signal in a fast ADC at constant illumination of photomultipliers. The theoretical description includes the effects of analogue filters, and photomultiplier afterpulses, digitization of the signal, and digital integration. In a comparison with measurements, possible errors in the calibration induced by drifts are analyzed and discussed.