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

Poznan 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 C-14 systems. Despite simpler construction of the AMS spectrometer, the quality of our C-14 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 (approximate to0.1 pMC), it is still a minor part of our C-14 blank (0.25-0.3 pMC), which is comparable to that found in many AMS C-14 facilities. Our standard precision of single cathode C-14/C-12 measurement of a modern sample corresponds to 0.3 per mil. This, together with simultaneous measurements of C-13/C-12 ratio (and correction for isotopic fractionation), enables single cathode C-14 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. (C) 2004 Elsevier B.V. All rights reserved.