Calculation of time resolution of scintillation counters with constant fraction discriminators

Constant fraction discriminators have been used for a long time in scintillation counters. In spite of that the author has so far not encountered in the literature a description of the dependence of the random timing error resulting from stochastic phenomena in such counters on parameters and energy. In this paper expressions, allowing random timing error calculation on the basis of the energy involved and parameters of scintillator, photomultiplier and cf discriminator, are given. Comparison to experimental results indicates that those substantially agree with the analysis. The paper also presents some experimental results concerning scintillation counters using fixed threshold discriminators and some comments about their agreement with the calculation results using existing theoretical expressions. Predictions of the error for some scintillators when using cf discriminators are given also.