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MS: Fachverband Massenspektrometrie

MS 8: Accelerator Mass Spectrometry II

MS 8.4: Vortrag

Donnerstag, 23. September 2021, 14:45–15:00, H3

Increasing the ionization yield for the detection of ²³⁶U and ²³³U by AMS — •Michael Kern, Karin Hain, Peter Steier, Andreas Wiederin, and Robin Golser — University of Vienna, Faculty of Physics - Isotope Physics, Vienna, Austria

The detection efficiency of Accelerator Mass Spectrometry for uranium isotopes ²³⁶U or ²³³U is mainly limited by the rather low yield of the corresponding negative ions extracted from a caesium sputter ion source (≈ 10⁻⁴). With our new sample preparation method environmental U is embedded in only 200 µg Fe₂O₃ matrix which is then mixed with PbF₂. Extracting U as UF₅⁻ instead of UO⁻ yields an improvement in detection efficiency of up to a factor of 10. Thus significantly shortened measurement duration can be obtained, while maintaining the same statistical uncertainty. UF₅⁻ extraction seems advantageous for the suppression of molecular isobaric background (²³³ThH³⁺, ²³³UH³⁺) and allows operation at lower He stripper gas pressure. This presentation will give detailed insights on the new sample preparation as well as ion current characteristics and method verification.