Abstract: A new AMS graphite target preparation line based on Fe/H₂ reduction method has been developed in the ¹⁴C laboratory at China Earthquake Administration,China. This paper demonstrates its performance on AMS-¹⁴C of internationally-accepted standards,known-age samples and blank measurements,and also discusses the reduction conditions of the graphite. The quality of this line is tested by the measurement of background and standard samples and the results show that the blank value of this line is between 0.45 and 0.49pMC,corresponding to the limited age of 45,700a,if the machine background is subtracted. We also have tested the reproducibility and memory effect of this line. Furthermore,we carried out the dendro-dated tree ring samples test and the comparison of different labs with same samples to test the reliability. These good results allow us to use the line in routine ¹⁴C dating.

Key words: accelerator mass spectrometry, graphite target preparation line, ¹⁴C dating

摘要： 中国地震局地质研究所¹⁴C实验室于2011年建立了一套新的铁氢法（Fe/H₂）制备加速器质谱仪（AMS）¹⁴C石墨靶系统，并对比不同温度、初始H₂：CO₂比例、不同活化铁粉等实验条件，以石墨合成效率和合成时间作为评判标准，筛选出最优的制备石墨的反应条件。在此基础上对一批本底样品（无烟煤，商业石墨）和标准样品（美国OX-Ⅱ，中国碳糖）进行了测试来检验系统的性能。结果表明：系统的本底值为0.45～0.47pMC，加速器本底为（0.13±0.01）pMC，扣除加速器本底，系统测年上限可达到45.7ka BP，稳定性良好。此外，还对系统进行了记忆效应检验和已知年龄树轮及相同样品不同实验室测定结果对比的实验，进一步检验系统的可靠性。实验结果表明，新系统合成的石墨靶满足加速器质谱仪的要求，可以进行¹⁴C年龄测定。

关键词: 加速器质谱仪, 石墨制靶系统, ¹⁴C测年