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Since radiocarbon age is a hypothetical age based on assumed model, conversion to real age (calendar age) are required for practical dating. The dataset used for conversion to real age from radiocarbon age has been constructed by international consortium and is called INTCAL calibration curve. Most parts of radiocarbon calibration dataset have been constructed by measuring ^<14>C concentration in dendrochronologically dated tree-ring samples from woods in Europe and North America. Regional ^<14>C offsets from INTCAL have been frequently argued based on the some systematic difference found in samples from different regions. In Japanese archeology, detailed chronology based on pottery typology has been established. So a resolution in a few tens of years is required for any chronologies to be fully developed. In order to provide high-resolution age required, it is important to investigate local effect in ^<14>C concentration in Japan. The wood sample used in this study was a bog wood of Japanese cypress found at Iida, Nagano Prefecture. It included tree-rings of 705 BC to 193 BC which was dendro-chronologically dated. The sample was cut into 5 years tree-ring specimens. Alpha-celluloses were extracted by AAA treatments, and bleaching with chlorine, and assayed into graphite targets. AMS measurements were performed at Nagoya University. The results obtained by our work indicate that the difference in radiocarbon age from IntCal04 is negligible in the range studied. However, we found a significant disagreement of about 50 ^<14>C years peaking at around 370 BC, where the calibration curve have a steep declining slope. The feature found in Japanese wood samples from 400 BC to 300 BC is smoother than the IntCal04 calibration curve.
第18回名古屋大学年代測定総合研究センターシンポジウム平成17(2005)年度報告 Proceedings of the 18th symposiumon on Chronological Studies at the Nagoya University Center for Chronological Research\in 2005 日時:平成18 (2006)年1月17日(火)､18日(水) 会場:名古屋大学シンポジオン Date:Januaryl7th and 18th, 2006 Venue:Nagoya Uhiversity Symposion Hall
名古屋大学加速器質量分析計業績報告書 17 130-134, 2006-03