Absolute Number Calibration of Photoelectrons of Photomultiplier Tubes using the Nature of Statistical Distribution

To obtain precise number of photoelectrons emitted from the photoelectric surface of photomultiplier tubes in short time simply and effectively is very important for experiments which use many photomultiplier tubes. The number of photoelectrons can be estimated from a formula which is made based on a statistical distribution. We have examined the precision of this formula by simulations and experiments. As a result, we found that the formula can be used very precisely after some corrections which depends mainly on the emission number of secondary electrons from the first and second dynodes of the photomultipliers.