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 The ion source has been replaced by a new one with better performance and reliability.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

摘要： 加速器质谱¹⁴C测量误差的主要来源是¹⁴C计数的统计误差与束流传输的不稳定性。对高精度测量还要考虑束流积分仪中IFC的非线性及离子源中弹坑效应引起的时变分馏。为得到高精度的样品年代数据，除提高¹⁴C测量精度外，还要用系列样品进行高精度的树轮校正，并采取必要措施保证测量结果的可靠性。

关键词: 加速器质谱, ¹⁴C测年, 高精度