Validation of a loss-free counting system for neutron activation analysis with short-lived indicators

The use of loss-free counting systems makes possible the exact correction for pile-up and dead-time losses during counting of a mixture of short-lived radionuclides even at very high count rates. However, counting statistics cannot be calculated by taking into account only the Poisson distribution of the incoming γ-quanta, such as is done in existing computer programs for γ-spectrometry. At moderate count rates Muller statistic was found to account for the observed variability between duplicate countings; however, at higher count rates the variability of weighing factors was found to be significant in comparison with the Muller statistic. While counting statistics could not be correctly estimated for short-lived species, experiments showed excellent accuracy for initial dead times up to 90%.