Radioactivity determination of individual radionuclides in a mixture by liquid scintillation spectra deconvolution.

A spectrum deconvolution method has been applied to logarithmic liquid scintillation spectra containing more than one radionuclide, to determine the activity of the individual components. The shape of the sample spectrum has been used for resolving the various components in the sample by fitting the reference spectrum of each component to the measured composite spectrum. The procedure has been applied to environmental samples containing (90)Sr, (90)Y and (85)Sr, added as a tracer for the chemical recovery determination. Comparisons are made with results obtained using a modified window-based method and results obtained by measuring the (85)Sr activity by gamma-ray spectrometry and subtracting its contribution to the LS count rate. It is demonstrated that this treatment of the beta-particle spectra represents a rapid and reliable method of determining these radionuclides in a mixture, even at low activity levels.