Hannover 2016 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 9: Accelerator Mass Spectrometry and Applications II
MS 9.6: Talk
Thursday, March 3, 2016, 16:00–16:15, f128
Dating with Atom Trap Trace Analysis of 39Ar — •Sven Ebser1, Zhongyi Feng1, Lisa Ringena1, Florian Ritterbusch1,2, Arne Kersting2, Stefan Beyersdorfer2, Emeline Mathouchanh2, Werner Aeschbach2, and Markus K. Oberthaler1 — 1Kirchhoff-Institute for Physics, Heidelberg, Germany — 2Institute of Environmental Physics, Heidelberg, Germany
Atom Trap Trace Analysis (ATTA) is an ultra-sensitive counting method for rare and long-lived isotopes. It is based on the high selectivity of resonant photon scattering during laser cooling and trapping in order to distinguish the rare isotope from the abundant ones. We have focused on the rare argon isotope 39Ar and developed an ATTA-setup. As an inert noble gas and with a half-life of 269 years it is the perfect tracer to fill the dating gap for ice and water samples between 50 and 1000 years before present, for which time period no other tracers exist. The experimental challenge lies in the low atmospheric abundance of 39Ar (39Ar/Ar = 8.23· 10−16) which requires a stable and reproducible performance of all components of the apparatus leading to a robust 39Ar detection efficiency. Our first results from groundwater samples reveal the potential of this table top experiment to routinely measure small samples down to 10 mL STP of argon. Furthermore, we will present current developments such as more efficient cooling techniques and optical pumping to enhance the flux of metastable argon atoms with the aim to increase the count rate. Shorter measurement times and smaller sample sizes together with a reduction of statistical uncertainties will thus become possible.