关键词: 加速器质谱, ¹⁴C测年, 高精度

Abstract: The precision and accuracy of AMS ¹⁴C dating have been studied. The main source of error comes from the statistical error of ¹⁴C counting and the instability of beam transmission efficiency. For high precision measurement the non-linearity error of current-frequency- conversion in beam current integrator and the time-dependent fractionation introduced by crater effect in ion source should also be considered. To meet the requirement of Xia-Shang-Zhou Chronology Project, PKUAMS upgrade was carried out. The stability of power supplies and the system vacuum were improved. The ion source has been replaced by a new one with better performance and reliability. With new data acquisition system the precision of lived time readout could reach 0.005%-0.01%. In order to obtain high precision age data, it is necessary not only to improve the precision of ¹⁴C measurements, but also to use the series samples in dendrological calibration by wiggle-matching method based on the Bayesian approach. The reliability of sample age depends on suitable sample selection and preparation, as well as the elimination of systematic error in measurement.

Key words: accelerator mass spectrometry(AMS), ¹⁴C dating, high precision