Nuclide analysis on low-statistics alpha-particle spectra: An experimental verification for Pu isotopes

In spectrometry with low-activity α-particle sources, deconvolution of multiplets which usually have poor statistics is a problem. In the present work, a peak-fitting model that is used successfully in metrology of α-particle spectrometry has been applied to the low-level case to identify problems and limitations. The method consists of measuring relative peak areas and peak positions in spectra of the single isotopes of interest. They serve to subsequently optimize (in the least-squares sense using constraints) the isotopic ratio in the spectra from the mixed-isotope sources. It is found that the method can perform reasonably well provided all sources have about the same thickness. Source thickness and the large solid angle produce peak deformation and increase coincidence summing with conversion electrons. At present they limit the application of the peak-fitting model.