The accelerator mass spectrometry facility at the Seoul National University (SNU-AMS) was completed in December 1998 and a report was presented at the Vienna AMS conference in September 1999. At the conference, we described the basic components of our accelerator system and reported the results of the performance test. Since then, extensive testing of the accuracy and reproducibility of the system has been carried out, and about 200 unknown samples have been measured so far. We obtained a precision of 4‰ for modern samples, and an accuracy of approximately 40 yr was demonstrated by analyzing samples that were previously dated with a conventional technique and by other AMS laboratories. We present these results here, together with detailed descriptions of our data-taking and analysis procedures.

ABSTRACT. We present the current status of accelerator mass spectrometry (AMS) dating of iron artifacts at Seoul National University (SNU). In ancient iron production, charcoal was widely used as carbon for the smelting process, whereas coal is used in modern times. If reliable data could be obtained from carbon by using AMS, ancient iron artifacts could be traced to their production age. In normal acid treatment, it is not easy to extract carbon due to its colloidal property. The negative charge property of the carbon colloid, however, makes it possible for it to be precipitated with positive ions by dissolving the iron chemically. An extraction yield of the carbon incorporated in modern cast iron of about 70% is attained. More refined methods to increase the extraction rate are under progress for archaeological applications.