• Establishment of Chemical Preparation Methods and Development of an Automated Reduction System for AMS Sample Preparation at KIGAM

      Hong, Wan; Park, Jung Hun; Kim, Kyeong J.; Woo, Hyung Joo; Kim, Jun Kon; Choi, Han Woo; Kim, Gi Dong (Department of Geosciences, The University of Arizona, 2010-01-01)
      Many previous studies on the sample preparation of various kinds of radiocarbon dating samples by accelerator mass spectrometry (AMS) have been examined at KIGAM (Korea Institute of Geoscience and Mineral Resources) and our own procedures have been established. Furthermore, an automated reduction system has been developed. The volume of the reduction region was minimized to improve the reduction yield, and air-actuated pneumatic valves and solenoid arrays were used for computer control of the system. Operation of all the valves and vacuum pumps and signals from the temperature sensors and pressure gauges were interfaced to a personal computer with an A/D board. A computer program was also developed to perform automatic operation of the reduction system. This system consistently shows a higher reduction yield than 90%. The reduction time of the system is currently 140 min.
    • Simple Pretreatment Method Development for Iron and Calcium Carbonate Samples

      Park, Junghun; Hong, Wan; Choi, Han Woo; Kim, Joonkon; Kim, Gi Dong (Department of Geosciences, The University of Arizona, 2010-01-01)
      Since iron artifacts generally contain trace amounts of carbon, an iron sample needs to be relatively large, as compared to other materials, and a specially designed combustion system is required. An elemental analyzer (EA) was used for the combustion of iron without any special chemical treatment. CO2 gas with 1 mg of carbon was obtained from the combustion of an iron artifact by using an EA and reduced to graphite for accelerator mass spectrometry (AMS) measurement. In this work, AMS dating results done at the Korea Institute of Geoscience and Mineral Resources (KIGAM) for several ancient iron artifacts are presented and compared with independently estimated ages. This method was found to be useful for the pretreatment of iron artifacts that contained 0.1% carbon. A simple pretreatment method using an EA was also applied to calcium carbonate (CaCO3) samples. Samples were preheated overnight at 100-300 C, without any special chemical treatment. This removed modern CO2 contamination and the background level decreased to a comparable value measured in samples treated with phosphoric acid under vacuum.