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 correct ion for pile-up and dead-time losses during counting of a mixture of s hort-lived radionuclides even at very high count rates. However, count ing statistics cannot be calculated by taking into account only the Po isson distribution of the incoming gamma-quanta, such as is done in ex isting computer programs for gamma-spectrometry. At moderate count rat es Muller statistic was found to account for the observed variability between duplicate countings; however, at higher count rates the variab ility of weighing factors was found to be significant in comparison wi th the Muller statistic. While counting statistics could not be correc tly estimated for short-lived species, experiments showed excellent ac curacy for initial dead times up to 90%.