The Fourth International Radiocarbon Intercomparison (FIRI)

The issue is devoted to the design and analysis of the Fourth International Radiocarbon Intercomparison, which aimed to define and improve the overall level of confidence in the direct comparison of information obtained from different measurement systems. The program focussed on assessing and establishing consensus protocols to be applied in the identification, selection, and sub-sampling of materials for subsequent analysis. A large-scale intercomparison then produced direct evidence on precision and accuracy, and provided a quantification of some of the main sources of variation associated with the measurements. As a result, a further series of 14C reference materials was created. The issue describes the selection, collection, and preparation of samples for use in the intercomparison; the design and organization of the laboratory intercomparison; the analysis and interpretation of the results; and concludes with a discussion of the future needs in the community and how the further tier of reference materials created can be used. Includes