Low-energy 14C AMS in Pozna Radiocarbon Laboratory, Poland

Abstract

Poznań Radiocarbon Laboratory is equipped with the “Compact Carbon AMS” machine produced by NEC, and the self-designed lines for graphite production from natural samples. Our AMS machine is characteristic first by a low voltage accelerator, that makes the spectrometer construction simpler, its size smaller and the maintenance easier than in case of the larger AMS 14C systems. Despite simpler construction of the AMS spectrometer, the quality of our 14C results is comparable to those obtained with larger AMS systems. A few months activity of the laboratory demonstrated high precision of the AMS machine and fine purity and good reproducibility of graphite target preparation. Though our AMS machine background is rather high (≈0.1 pMC), it is still a minor part of our 14C blank (0.25–0.3 pMC), which is comparable to that found in many AMS 14C facilities. Our standard precision of single cathode 14C/12C measurement of a modern sample corresponds to 0.3 per mil. This, together with simultaneous measurements of 13C/12C ratio (and correction for isotopic fractionation), enables single cathode 14C dating of young samples with an error of ±30 years. Accuracy of dating is not significantly worse, which has been demonstrated by the tests with samples of known age.