Basic Research for AMS Radiocarbon Dating of Iron Artifacts(Proceedings of the 16^<th> Symposium on Researches Using the Tandetron AMS System at Nagoya University in 2003)
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- 鉄製遺物の^<14>C年代測定法のための基礎研究 (第16回名古屋大学タンデトロン加速器質量分析計シンポジウム平成15(2003)年度報告)
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In order to establish a technique of AMS ^<14>C dating of archeological iron artifacts, we have started to develop a prototype of carbon extraction system from iron samples by combusting a part of iron samples with a RF induction furnace since 1994. In addition, we also have tested successfully a method of carbon extraction by dissolving iron samples in CuCl_2 solution since 1998. Presently, we have overcome most of the problems of the two carbon extraction systems and methods provide us acceptable performances; carbon yield is normally around 80% and a ^<14>C background level is as low as 42-48 ka BP in apparent ^<14>C age. We have conducted an iron refining experiment to examine what the ^<14>C age of carbon contained in iron artifacts means, by using AMS ^<14>C dating and carbon extraction systems so far established. The experiment was conducted for source iron slugs, by-products formed during an ancient iron production in the 7^<th> century AD, with fuel (reducing agent) of modern charcoal whose production age was clear. The aim of the experiment was to determine whether older carbon characteristics in the source iron materials would be preserved, or carbon would be renewed with modern charcoal partly or completely, after such a treatment. ^<14>C concentration of carbon contained in the newly produced iron by an iron refining experiment was the most important point to check. The experiment yielded the ^<14>C concentration equivalent to that of the modern charcoal fuel. The result of iron refining experiment indicates that original old carbon existed in the iron have been replaced with modern carbon that was used as fuel. AMS ^<14>C dating on iron materials gives the age of the final episode of an iron manufacturing, refining or blacksmithing process. On the basis of these results, we also dated iron artifacts excavated from iron production sites such as Gennaitouge, Motooka and Ninjihaijikita sites, and obtained ^<14>C ages consistent with archaeological ages estimated for those sites.
第16回名古屋大学タンデトロン加速器質量分析計シンポジウム(平成15年(2003年度)報告 Proceedings of the 16th Symposium on Researches Using the Tandetron AMS System at Nagoya University in 2003 日時:平成16(2004)年1月22日(木)､23日(金) 会場:名古屋大学シンポジオン Date:January 22nd and 23rd,2004 Place:Nagoya University Symposion Hall
名古屋大学加速器質量分析計業績報告書 15 83-102, 2004-03