14C dating of archaeological samples by AMS of Tokyo University

With an internal beam monitor method, a technique similar to that applied to 10Be, it is possible to obtain reasonably precise measurements of 14C/12C. The typical reproducibility was about ±2% for 14C/12C measurements of standard samples, and the best background level was 14C/12C < 3x10-16 which corresponded to an age of more than 67 000 years. 14C measurements were attempted on some archaeological samples. Two of them were charred seeds and pieces of wood, which gave results close to the background level. The other two samples were small pieces of skeletons of human hunter gatherers, from which collagen was extracted and 14C/12C ratios were measured. (orig.)