Mainz 2017 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 6: Accelerator Mass Spectrometry and Applications I
MS 6.1: Invited Talk
Wednesday, March 8, 2017, 14:30–15:00, RW 2
Laser Isobar suppression for cooled 26AlO− and 36Cl− ions — •Johannes Lachner, Andreas Kalb, Christoph Marek, Martin Martschini, Alfred Priller, Peter Steier, and Robin Golser — Faculty of Physics, University of Vienna, Austria
The newly developed Ion-Laser InterAction System (ILIAS) was connected to the Vienna Environmental Research Accelerator (VERA). ILIAS allows to slow down negatively charged ions to thermal velocities in a linear radiofrequency quadrupole (RFQ) filled with He gas. I will present our experiments on isobar suppression via collisions in the RFQ and via element selective photodetachment.
In the photodetachment experiments we used a 532 nm laser (18 W), which is coupled into the beamline and our RFQ via a viewport in a 90∘ magnet, the first filter after the negative ion source. The VERA mass spectrometer then allows identifying trace amounts of nuclides and molecules in the beam transmitted through the ion cooler. We studied the effects of collisions of the beam with He buffer gas and of laser photodetachment on the AMS-relevant ions 36Cl− and 26AlO−: Suppression factors of the isobars (26MgO− and 36S−) of 103 and 107, respectively, are realized. Sufficient suppression of the isobars in the ion cooler will allow for the choice of lower charge states after the accelerator and improve the yields of detection. We therefore tested different charge states for the nuclides of interest and report on the separation of the isobars and of m/q interferences at beam energies between 10 and 25 MeV using a multi-anode gas-ionization chamber. The new isobar suppression method will widen the capabilities of smaller and middle-sized AMS facilities and open the future for novel AMS isotopes.