Mainz 2026 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 8: Isobar Suppression Techniques
MS 8.5: Talk
Friday, March 6, 2026, 12:15–12:30, N 6
Collisional detachment of AlO− and MgO− in the ALIS RFQ ion cooler at CologneAMS — •Derin Schmidt1, Markus Schiffer1,2, Timm-Florian Pabst1, Natasha Goaba Kalanke3, Stefan Heinze1, and Dennis Muecher1 — 1University of Cologne, Institute of Nuclear Physics, Germany — 2University of Cologne, Department of Prehistoric Archaeology, Laboratory of Isotope Archaeology, Germany — 3Department of Physics and Astronomy, Botswana International University of Science and Technology, Botswana
Laser isobar suppression is currently revolutionizing AMS; however, the underlying atomic- and molecular-level mechanisms responsible for its exceptional photodetachment efficiency are not yet fully understood.
In the Anion Laser Isobar Separator (ALIS) at CologneAMS, a radio frequency quadrupole (RFQ) ion cooler filled with He buffer gas is used in combination with a high-power laser to suppress the 26MgO− molecular isobar in 26AlO− beams.
Systematic measurements of collisional detachment in this cooler are presented. For a stable 27AlO− beam, the transmission was measured as a function of He pressure.
The count rate in the gas ionization detector for standard materials was analyzed for different ion cooler He buffer gas pressures and normalized to the slow sequentially injected stable 27Al beam, to determine the ratio of collisional-detachment cross sections σcol(26MgO)/σcol(27AlO).
Keywords: Collisional Detachment; Photodetachment; CologneAMS; Aluminium-26