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Measurement of Uranium-236 in Particles by Secondary Ion Mass Spectrometry



David S. Simons, John D. Fassett


The determination of the relative isotopic abundance by secondary ion mass spectrometry of 236U in uranium-containing material is complicated by the presence of 235U1H+ ions at the same nominal mass as the uranium isotopic peak. The net intensity of the 236U signal is usually determined by a peak-stripping procedure, whereby the 235U1H+ contribution is obtained by applying the 238U1H+/238U+ ratio to the 235U+ signal. The subtraction of one signal from another has consequences for the uncertainty of the final 236U abundance determination that may be especially significant when the amount of sample is limited, as is the case with small uranium particles that are of great interest for nuclear safeguards. We have developed a model based on Poisson counting statistics to determine the effects of various parameters on the uncertainty of the 236U abundance, including uranium enrichment level, hydride-to-parent ratio, uranium mass consumed during analysis, single versus multichannel counting, and sample substrate composition.
Journal of Analytical Atomic Spectrometry


hydride, isotope, isotopic abundance, particle, secondary ion mass spectrometry, SIMS, uranium


Simons, D. and Fassett, J. (2017), Measurement of Uranium-236 in Particles by Secondary Ion Mass Spectrometry, Journal of Analytical Atomic Spectrometry, [online], (Accessed April 15, 2024)
Created January 12, 2017, Updated January 27, 2020