Improvements of PKUAMS for precision 14C analysis of the project of Xia–Shang–Zhou Chronology

To meet the requirements of the Xia‐Shang‐Zhou Chronology project, an upgrade of the AMS facility at Peking University has been carried out, commencing in 1996, and a new sample preparation system with high eAciency and low memory has been set up in the Department of Archaeology. A NEC MC-SNICS ion source has been installed and the injection system has been reconstructed. Computer control of the beam line has been implemented using Group 3 ControlNet, and a new data acquisition system has been developed. The alignment and vacuum of the beam line have also been improved. The upgraded system was commissioned in 1998. Subsequent experience has led to eAcient procedures for beam tuning and 14 C/ 13 C measurement. A precision of 0.5% in the 14 C/ 13 C ratio has been achieved. Many samples have now been measured for the Xia‐Shang‐Zhou Chronology project. ” 2000 Elsevier Science B.V. All