Absolute determination of 79Se/80Se with AMS

Selenium-79 measurement with accelerator mass spectrometry (AMS) is increasingly being used for the determinations of 79Se relevant nuclear data. Furthermore, 79Se was deemed to be an ideal tracer nuclide for long-period and non-intrusive biological studies on selenium. An ultra-sensitive AMS measurement method of 79Se has been established at the CIAE-AMS system. For further applications of 79Se-AMS, reference standards were requested. 79Se can be derived from the 78Se(n, γ)79Se reaction but cannot be accurately quantified by theoretical calculation owing to the small and dubious cross section and other relevant parameters. In this paper, an AMS method has been developed for the absolute determination of the 79Se/80Se ratio in a 79Se sample with relatively high 79Se content. The relative standard uncertainty of 79Se/80Se ratio is 4.7% and a reference standard is thus acquired. The results are favourable for further applications of 79Se-AMS.