TIME DISTORTION OF A POISSON-PROCESS AND ITS EFFECT ON EXPERIMENTAL UNCERTAINTY

By means of computer simulations of spectrometry counting, the effect of pulse pileup and system dead-time on the experimental uncertainty i s investigated and compared with theoretical expectations. Different c ounting statistics are observed depending on the type of count loss, i .e. due to pulse pileup, extending or non-extending system dead-time o r a combination of these mechanisms. Simulations were also applied to test the ability of ''loss-free counting'' to deal with the different event loss mechanisms, and to assess the corresponding counting uncert ainty. Some findings have been tested experimentally by comparison wit h the statistical behaviour observed in real gamma-spectrometry at hig h incoming pulse rate, including the counting uncertainties in loss co rrected spectra (LFC with virtual pulser). (C) 1998 Elsevier Science L td. All rights reserved.