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MS: Fachverband Massenspektrometrie
MS 6: New Methods, AMS II, Applications, Actinides
MS 6.4: Talk
Wednesday, March 13, 2024, 18:00–18:15, HS 3042
Residence time measurements of Cl− ions inside the ILIAMS cooler in equilibrium — •Felix Albrecht, Martin Martschini, Michael Kern, Peter Steier, and Robin Golser — University of Vienna, Faculty of Physics, Austria
The ILIAMS (Ion-Laser InterAction Mass Spectrometry) ion cooler, developed at VERA (Vienna Environmental Research Accelerator), plays a pivotal role in providing isobar separation for isotopes that are typically inaccessible to mid-energy accelerator mass spectrometry systems. By combining a gas-filled RFQ ion guide with high-powered lasers, ILIAMS suppresses unwanted isobaric anions via laser photodetachment. The suppression efficiency is limited by the ion residence time inside the cooler, which can be varied mainly through the buffer gas pressure and the guiding field strength.
For the first time, measurements of the ion residence time at equilibrium conditions were performed using a new, custom-built multi-beam switcher. Through sequential injection of the stable isotopes 35Cl− and 37Cl−, followed by mass separation by a Wien filter, the buildup- and washout functions of both ion species were observed. The about 3-times higher-current 35Cl− beam pushed the previously injected, lower-current 37Cl− ions through the cooler, yielding a peak in the washout function. This allowed for a direct observation of space charge effects inside the ILIAMS cooler.
Similarly, by pulsed injection of 37Cl− into a 35Cl−-filled cooler, residence time distributions of the former were directly measured.
Keywords: AMS; ion optics; residence time; space charge; chlorine