Calibration of the 58 AVP type photomultiplier

Methods for and results of calibrating the pulse output from a 58 AVP photomultiplier used in an experiment with a Dirak monopole are discussed. The anode pulse amplitudes were calibrated using the observed fluctuations of electron pulses from standard multielectron flashes. The standard flash source was a photo diode, type AL 102B. The photodiode was fed with pulses from a generator with a duration of less than 10 ns, following with a frequency of 100 Hz. Light from the source was focused in an 80-mm-dia spot. The intensity of the spot was monitored with two film polaroids. The amplitude of a single photoelectron pulse of the anode current at the light spot was typically 20-40 μA. Calibration was done before and after each exposure to an accelerator. The calibration precision, assuming the same coefficient of secondary emission for all dynodes, was about 12%