A new technique for thick source alpha counting determination of U and Th

A new technique for the calculation of U and Th concentration is presented based on the alpha particle spectrum taken from a thick sample by using a s ilicon detector. Four approaches to the analysis of the experimental data a re presented, one being an improvement on the known pairs technique. By the proposed technique it is possible to calculate the concentrations of certa in daughter nuclides in the two series, or the sum of the activity concentr ations of others. This allows the detection of secular disequilibrium in ou r samples. This technique also has the advantage of being more accurate and provides the opportunity to cross-check the results derived from the diffe rent approaches. (C) 2000 Elsevier Science B.V. All rights reserved.