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VERA Seminar

Slow anion beams in the spotlight of a green laser

Johannes Lachner, Faculty of Physics, Isotope Research and Nuclear Physics, University of Vienna

The separation of rare trace isotopes from their isobars, i.e. atoms or molecules of very similar mass, is the major challenge of sensitive mass-spectrometric methods. The experimental setup at the Vienna Environmental Research Accelerator (VERA) was expanded with an ion cooler on the injection side, which allows for additional isobar suppression via interaction of negative ions (anions) with a laser beam. The anion beam is decelerated electrostatically and in collisions with He buffer gas inside a radio-frequency quadrupole. Element-selective photodetachment of the slowed-down ions is achieved by overlapping the ion beam with an intense photon beam.

Our first application of the combined setup was to separate the particularly interesting isobar pairs 36Cl/36S and 26AlO/26MgO using 2.33 eV photons (532 nm from a Nd:YAG laser). In these experiments we have observed various surprising disappearances of molecules as well as emergences of new molecular anions from the ion cooler. As the photodetachment on the low-energy side makes high beam energies redundant for isobar separation we can turn our focus also on setups to measure 26Al and 36Cl at lower beam energies. I will show results for charge states 2+ or 3+ on the high-energy side of the accelerator with special regard to the separation and suppression of the numerous potential m/q interferences.


Donnerstag, 18.05.2017    16:30 Uhr

Währinger Str. 17 (Kavalierstrakt, Zugang durch den Hof)
1090 Wien


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