The Pile-Up Problem in Pulse Fluorometry

Abstract

In this first contribution we consider the single-photon counting experiment. This is followed by a discussion of the Poisson process. The most important function to be described is the zeroth pulse interval density, which corresponds to the experimental result. Only in the limit of a low mean photon count rate (as a ratio to pulse repetition rate), does this function correspond to the required true time-dependence of the fluorescence. In other cases either an electronic pile-up inspector must be used, or the zeroth pulse interval density function itself should be fitted. The distinction between electronics-limited (type E) pileup, and statistical TAC-limited (type S) pile-up is clearly made. Finally, (rather than earlier, where the issues are already confused enough), the nature and variety of dead times are considered in more detail.