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MS: Fachverband Massenspektrometrie
MS 11: Accelerator Mass Spectrometry and Applications III
MS 11.6: Vortrag
Freitag, 4. März 2016, 12:30–12:45, f128
41Ca measurements at 500 kV — •Christof Vockenhuber — Laboratory of Ion Beam Physics, ETH Zurich, Switzerland
41Ca is an AMS isotope particularly interesting for biomedical applications. We have improved the performance of 41Ca measurements using low-energy AMS at the 500 kV AMS system TANDY at ETH Zurich for reliable measurements and high sample throughput. In order to simplify sample preparation CaF3− ions from CaF2 material are used to suppress the interfering stable isobar 41K in the ion source by a large amount. The transmission for Ca2+ ions through the tandem accelerator at 500 kV is >50% with He stripping. However, at this low energy 41Ca and 41K cannot be separated in the gas ionization detector. Instead the beam switching system is utilized to correct measured 41Ca rates for the 41K contribution. For this purpose, 41Ca2+ and 39K2+ ions are sequentially injected and counted in the detector. Assuming a natural 41K/39K ratio the measured 41Ca/40Ca ratios can be corrected for the K content and allows measurements down to 10−12 range. The measurement procedure and some applications are discussed.