Deconvolution of alpha liquid scintillation spectra for quantitative analysis of actinide elements in water samples

Abstract

Summary The reliability and accuracy of actinide measurement in environmental samples strongly depend on the α-spectrum deconvolution process used to identify all radionuclides present in the sample, and the necessity to take into account internal conversion is demonstrated. In this process, all actinides can be resolved as the sum of three peaks: the main alpha transition and two sum peaks for which the additional α ray is merged with the internal conversion on L-shell peak and with all other conversions on M-shell, N-shell, etc. The intensity of the internal conversions for thorium, uranium, plutonium and americium have been calculated and normalised to the intensity of the main alpha transition. These data can be used to determine the activity of any above-mentioned actinide by alpha liquid scintillation with alpha/beta discrimination. The quantitative analysis and the isotopic ratio determination of several certified solutions of actinides demonstrate the validity of this approach.