Hannover 2016 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 7: Accelerator Mass Spectrometry and Applications I

MS 7.3: Vortrag

Donnerstag, 3. März 2016, 11:45–12:00, f128

Carrier free ¹⁰Be/⁹Be measurement with AMS — •Johannes Lachner¹, Marco Ploner¹, Aya Sakaguchi², Peter Steier¹, and Robin Golser¹ — ¹Faculty of Physics, University of Vienna, Austria — ²Faculty of Pure and Applied Sciences, University of Tsukuba, Japan

Measuring ¹⁰Be/⁹Be ratios is a powerful tool to date marine deposits in the range of million years if it succeeds to determine minute amounts of the long-lived ¹⁰Be and the stable ⁹Be. The low abundance of Be in natural samples poses challenges to the preparation of samples and to very sensitive measurements of both ¹⁰Be and ⁹Be. The high efficiency of BeO⁻ extraction from the Fe₂O₃ target matrix in combination with a good transmission from the low energy side into the detector enables us to measure 0.1% of the total material during the first hour of sputtering a target. Ion source cross-contamination from intense standards and traces of Be taken up during the preparation of the targets currently limit the background to levels of 0.06 counts per second (¹⁰Be) and 15 pA (⁹Be²⁺). We present the establishment of the carrier-free Be method at the VERA laboratory and show results of Fe-Mn crusts from the Pacific Ocean dated back to 17 Myr.