Beta spectrum unfolding for measurement of multiple labeled samples

The paper presents the results obtained in the implementation and validation processes for a liquid scintillation spectrometric method used to measure low energy beta activity in multilabeled samples containing high energy beta emitters (impurities). The method is based on deconvolution of the total spectrum with reconstruction of the spectral contribution for every individual radionuclide. The hypothesis used is that the ratio of the net counting rate in two different regions for a given radionuclide is a constant for a given level of quench and thus the spectral shape of the radionuclide could be reconstructed by using a reference spectrum at the same quench level. The advantage of the method consists in the fact that it does not require setting up quench correction curves. Just the activity concentration for the standard solution from nuclide of interest should be accurately known. When the activity concentrations for reference solutions of the impurities are known, the activities of the impurities could also be calculated. The technique has been successfully used on experimental samples containing H-3 as radionuclide of interest and Sr/Y-90 as impurities. (authors)