SAMOP 2023 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 6: Accelerator Mass Spectrometry II

MS 6.6: Vortrag

Donnerstag, 9. März 2023, 15:45–16:00, F128

Lowering the background levels of ¹⁴C AMS measurements at CologneAMS — •Tom Sittig, Martina Gwozdz, Stefan Heinze, Markus Schiffer, Elisa Chopan, Gereon Hackenberg, Timm Pabst, and Dennis Mücher — Institute for Nuclear Physics, University of Cologne, Germany

AMS CO₂ gas measurements are useful as they allow for ultra small sample sizes to be analysed. A low background is important to achieve reliable and reproducible ¹⁴C/¹²C ratios. Because previously these background levels were higher than expected at CologneAMS when performing blank measurements, a source of contamination was investigated. As the result a new preparation routine has been implemented at the 6MV AMS system of CologneAMS.

By including the target holders alongside the CO₂-targets during heating for an extended period of time, followed by cooling both to room temperature under an argon atmosphere, we were able to decrease the background level by 60%. The new blank ratios are consistent with the machine blank level at 3.7·10⁻¹⁵±18%. The stability of background levels is also improved and consistent with statistical expectations.

This increased stability allows us to investigate the sources of memory effects observed in cases where samples with low ¹⁴C contents were preceded by samples with high ¹⁴C content, optimising our setup even further in the future.