Heidelberg 2015 – scientific programme

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MS: Fachverband Massenspektrometrie

MS 10: Accelerator Mass Spectrometry and Applications 2

MS 10.6: Talk

Wednesday, March 25, 2015, 18:30–18:45, PH/HS2

¹³⁵Cs at VERA - developments for a new AMS isotope — •Johannes Lachner, Magdalena Kasberger, Martin Martschini, Alfred Priller, Peter Steier, and Robin Golser — VERA Laboratory, University of Vienna, Faculty of Physics, Austria

Decreasing activities of ¹³⁷Cs (T_1/2=30.2 yr) in environmental samples complicate the decay counting measurements of this important isotope for radioecological assessment. This raises the interest in mass spectrometric methods for the measurement of radioactive Cs isotopes. Due to its longer half-life (T_1/2=2.3 Myr), the sister isotope ¹³⁵Cs is even more suited for MS techniques. The combined measurement of the two isotopes would allow identification and tracing sources of contamination. At the current stage, the isobars ^135,137Ba prohibit measurements in samples from the general environment.

We present results for AMS measurements of Cs concerning negative ion formation, transmission through the accelerator and detection obtained at the 3 MV VERA facility. In addition to its use for the production of negative Cs beams, Rb sputtering was tested during these measurements for various AMS elements. In the present setup and in chemically pure samples of Cs₂SO₄, ¹³⁵Ba can be suppressed to ¹³⁵Ba/¹³³Cs ratios of ≈10⁻⁹ . Further potential for isobar suppression is expectable after the future installation of the Ion-Laser-Interaction system (ILIAS) at VERA.