The in-growth of 241Am from the decay of 241Pu is a well-regarded chronometer for the determination of the time since last chemical-separation in plutonium-based nuclear forensics samples. Alpha-spectrometry software will be presented that determines the relative amount of 241Am in plutonium special nuclear material with about a 1% (k = 2) total uncertainty. This is achieved by incorporating Pu isotopics determined by thermal ionization mass-spectrometry into the analysis and by utilizing accurate conversion-electron and tailing functions. Due to the lack of a consensus americium in bulk plutonium standard, it is difficult to determine overall measurement bias. Therefore, a total measurement uncertainty is determined by a GUM (Guide to the Expression of Uncertainty in Measurement) bottom-up methodology. Sources of uncertainty include Poisson statistics, nuclear data, deconvolution, interferences and sample inhomogeneities.

Software and analysis methods for the determination of americium in plutonium via alpha spectrometry

256th National Meeting (2018)

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