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MS: Fachverband Massenspektrometrie

MS 14: Accelerator Mass Spectrometry and Applications 4

MS 14.1: Hauptvortrag

Freitag, 27. März 2015, 11:00–11:30, PH/HS2

AMS detection of actinides at high mass separation — •Peter Steier¹, Rosmarie Eigl², Johannes Lachner¹, Alfred Priller¹, Francesca Quinto³, Aya Sakaguchi⁴, Stephan Winkler¹, and Robin Golser¹ — ¹University of Vienna, Faculty of Physics, Vienna, Austria — ²Hiroshima University, Earth and Planetary Systems Science, Hiroshima, Japan — ³Institut für Nukleare Entsorgung, KIT, Eggenstein-Leopoldshafen, Germany — ⁴University of Tsukuba, Center for Research in Isotopes and Environmental Dynamics, Tsukuba, Japan

AMS is the mass spectrometric method with the highest abundance sensitivity, which is a prerequisite for measurement of the long-lived radioisotope ²³⁶U (t_1/2=23.4 million years). The most successful application so far is oceanography, since anthropogenic ²³⁶U is present in the world oceans at ²³⁶U:²³⁸U from 10⁻¹¹ to 10⁻⁸. We have explored methods to increase the sensitivity and thus to reduce the water volume required to 1 L or less, which significantly reduces the sampling effort. High sensitivity is also necessary to address the expected typical natural isotopic ratios on the order ²³⁶U:²³⁸U = 10⁻¹³, with potential applications in geology.

With a second 90^∘ analyzer magnet and a new Time-of-Flight beam line, VERA is robust against chemical impurities in the background, which e.g. allows measuring Pu isotopes directly in a uranium matrix. This simplifies chemical sample preparation for actinide detection, and may illustrate why AMS reaches lower detection limits than other mass spectrometric methods with nominally higher detection efficiency.