On the Development and Validation of a Digital Coincidence Counting System for the Primary Standardisation of Radionuclides

For decades, the electrical outputs from nuclear particle detectors used in the 4pi-beta-gamma coincidence counting technique for the absolute standardisation of radioisotopes have been analysed using sophisticated analogue techniques. Recent advances in the performance of digital signal acquisition technologies have facilitated a means of registering pulse shapes and arrival times for events from both channels of a coincidence counting system, at count-rates enabling adequate precision of the technique. In this thesis, the development of such a dedicated digital data acquisition system is discussed, and a suite of highly modular and re-usable software analysis routines is presented. Such a scheme yields unsurpassed flexibility in the application of particle counting regimes with respect to standard analog methods. Emphasis has been placed on the validation of the analysis software routines, which primarily proceeds via the use of a dedicated Monte-Carlo simulation software package, developed in this project. The precise estimation of the true rate of a sampled Poisson process requires access to the distribution of intervals between subsequent events. New formulae are presented for the moments of such interval distributions, where the process has been perturbed by the insertion of a non-extending dead-time, particularly for the case where one is only interested in a particular region of the total distribution.

KEIGHTLEY John; 

2009-01-07

University of London - Imperial College London

JRC49500

https://publications.jrc.ec.europa.eu/repository/handle/JRC49500,