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Uncertainty of nuclear counting



Stefaan Pomme, John Keightley, Ryan P. Fitzgerald


Nuclear counting is affected by pulse pileup and system dead time which induce rate-related count loss and alter the statistical properties of the counting process. Fundamental equations are presented to predict deviations from Poisson statistics due to non-random count loss in nuclear counters and spectrometers. Throughput and dispersion of counts are studied for systems with pileup, extending and non-extending dead time, before and also after compensation for count loss. Equations are provided for random fractions of the output events, applicable to spectrometry applications. Methods for loss compensation are discussed, incl. inversion of the throughput equation, live-time counting and loss-free counting. Secondary effects in live-time counting are addressed: residual interference from pileup in systems with imposed dead times and errors due to varying count rate when measuring short-lived radionuclides.


nuclear counting, dead time, pulse pileup, radionuclide metrology, counting statistics


Pomme, S. , Keightley, J. and Fitzgerald, R. (2015), Uncertainty of nuclear counting, Metrologia, [online],, (Accessed June 21, 2024)


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Created May 21, 2015, Updated October 12, 2021