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MS: Fachverband Massenspektrometrie

MS 5: Poster

MS 5.6: Poster

Dienstag, 11. März 2025, 17:30–19:00, Foyer Physik

AMS-detection of ¹⁸²Hf: Characterization of new low-level reference materials and cross-contamination experiments — •Laurenz Widermann¹, Martin Martschini¹, Silke Merchel¹, Sebastian Fichter², Dominik Koll^2,3, Johannes Lachner², Johannes H. Sterba⁴, Anton Wallner², and Robin Golser¹ — ¹University of Vienna, Faculty of Physics, Austria — ²HZDR, Dresden, Germany — ³TUD Dresden University of Technology, Dresden, Germany — ⁴TRIGA Center Atominstitut, TU Wien, Vienna, Austria

To detect the potentially supernova-produced radionuclide ¹⁸²Hf (t_1/2=8.9 · 10⁶ yr) as low as 2.2 · 10⁴ atoms per ferromanganese crust sample with Accelerator Mass Spectrometry (AMS), the stable isobar ¹⁸²W needs to be suppressed by six orders of magnitude.

Ion-Laser InterAction Mass Spectrometry (ILIAMS) in Vienna allows suppression of ¹⁸²WF₅⁻ by a factor of 10⁵. New low-level reference materials prepared from a known activity of ¹⁸²Hf, with ¹⁸²Hf/¹⁸⁰Hf ratios between 10⁻¹³–10⁻¹¹, were characterized and cross-checked against ViennaHf-10 and ViennaHf-11. These previously used materials have too high ¹⁸²Hf/¹⁸⁰Hf ratios (>10⁻¹⁰) to allow measurements at the 10⁻¹⁴ level expected from crust samples.

New isobar spikes for correcting A =182 counts for residual ¹⁸²W were investigated at the AMS-facilities in Vienna and Dresden. Sputtering targets spiked with varying amounts of tungsten revealed both short-term cross-contamination and long-term memory effects.

This work is supported by ChETEC-INFRA (H2020 #101008324).

Keywords: AMS; Nuclear Astrophysics; Hafnium-182; Isobar Suppression