Erlangen 2022 – wissenschaftliches Programm
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MS: Fachverband Massenspektrometrie
MS 4: Accelerator Mass Spectrometry
MS 4.2: Vortrag
Mittwoch, 16. März 2022, 11:00–11:15, MS-H9
Why and how producing an isotopic spike for the analysis of environmental 237Np — •Karin Hain1, Martin Martschini1, Aya Sakaguchi2, Peter Steier1, Andreas Wiederin1, Akahiko Yokoyama3, and Robin Golser1 — 1University of Vienna, Faculty of Physics, Austria — 2University of Tsukuba, Faculty of Pure and Applied Science, Japan — 3Kanazawa University, Institute of Science and Engineering, Japan
The quantitative analysis of the potential oceanographic tracer 237Np by mass spectrometric techniques such as Accelerator Mass Spectrometry (AMS) still suffers from the lack of an isotopic spike. Measurements using non-isotopic spikes for normalisation, such as 242Pu, have achieved acceptable results for selected environmental materials, but require careful control of the oxidation states during chemical separation and monitoring of the relative ion source output. In our joint project with the University of Tsukuba we successfully produced mass 236 by the irradiation of Th foils with a 7Li beam in the 30-40 MeV range at the RIKEN Nishina Center. First AMS measurements using fluoride molecules indicate that the observed surplus of mass 236 above background is indeed 236Np. The by-production of mass 237, however, is higher than expected from model calculations with the EMPIRE code and needs further investigation. This contribution will discuss environmental levels of 237Np obtained with AMS using non-isotopic normalisation and the present status of the 236Np spike production.