Calibration of AMS C-14 ages prior to 20,000 years B.P. or more, using Fission Track ages of burnt obsidians

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The purpose of this research is to examine the degree and tendencies of the discordance of measured ages by two dating techniques (AMS C-14, FT) of the sample (charcoal and burnt obsidian, respectively) of simultaneous derivation. However, mostly because of the difficulties in FT dating, we couldn't obtain sufficient results.The Nagano series obsidians were glass-clear quality, and gave FT ages with 5% counting errors. However, the association status of charcoal and burnt obsidian depends on the third level of reliance (stratigraphic).To overcome these difficulties, the Hokkaido series obsidians were added. Their association status was second level (archaeological). However, due to fission-track-like etch pits derived from crystalline properties, and the small size of the specimens, it was difficult to obtain reliable and reproducible FT ages.As a result, we couldn't calculate conversion factors for AMS C-14 versus FT ages.Especially in the case of Hokkaido series, S/N (signal/noise) ratios were extremely low - beyond the limits of human vision?Therefore, research like this should be oriented for, as a first step, automatic and instrumental FT measurement that is urgently required.We have published papers and reports, including an oral presentation in a related field, all of which have been collated in the booklet report.