O01_P06

Studying ¹⁴C production in meteorites using the Bernese ¹⁴C extraction line and the MICADAS system at LARA, University of Bern

Tauseef M¹, Leya I¹, Szidat S², Gattacceca J³

¹Space Research and Planetary Sciences, University of Bern, , Switzerland, ²Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, , Switzerland, ³CNRS, Aix Marseille University, CEREGE,  Aix-en-Provence, France

Carbon-14 dating is the most robust technique for determining the terrestrial ages of meteorites. With our updated ¹⁴C extraction system, we can measure up to 15 samples without breaking the vacuum, thereby achieving low blanks and a high sample throughput (Sliz et al. 2018, 2020). Briefly, we are able to quantitatively and reproducibly extract CO₂ gas from pre-cleaned meteorite samples (typical masses 50 mg). Preheating the samples at 500 °C in a continuous flow of pure oxygen reduces the remaining atmospheric contamination. Gas extraction is at ~1600 °C under an O₂ partial pressure of 30±5 mbar for 10 min. Evolved gases are first purified at 500°C –1000°C using CuO, quartz spherules, and silver wool. Next, gases are cleaned and separated using a water trap at –78 °C and cold fingers (~100 °C). The purified CO₂ gas is then collected in a glass capillary and is subsequently introduced into the gas ion source of the MICADAS AMS system (University of Bern). We finally give our results as specific activity concentrations (dpm/kg), which are then used to determine the terrestrial ages of meteorites. Here we will present new data for ¹⁴C and ¹⁰Be activity concentrations in freshly fallen meteorites to better constrain the ¹⁴C and ¹⁰Be production rates and consequently determine more accurate and more precise terrestrial ages of meteorites.

References

Sliz M.U. et al. 2018. 81st Annual Meeting of The Meteoritical Society 2018 (LPI Contrib. No. 2067)

Sliz M.U. et al. 2020. Radiocarbon Vol 62, Nr 5, p 1371–1388