First discovered and manufactured in Berkeley Radiation Laboratory in 1940, the isotope carbon-14 (C-14, also called radiocarbon) has since played a fundamental role in the development of biomedical sciences, human sciences and environmental sciences. This project aims to produce an up-to-date history of its first applications in Europe, by exploring the circulation of materials, instruments and techniques based on this isotope after World War 2. In particular, research will focus on three case studies of appropriation of isotopic tracing techniques, which will be approached from a transnational perspective: the use of C-14 techniques by molecular biologists, the use of radiocarbon in archeological dating and the use of carbon-14 in environmental sciences. The study of the use of similar techniques in different disciplines will allow for an analysis on interdisciplinary connections between fields, and also for a comparative study of the transfer and validation of these techniques among different research communities. Besides studying these methodological and epistemological questions, the project will result in a up-to-date chronology and a guide of sources on the history of nuclear sciences in Europe, as well as a repository of oral interviews to key actors in thsi field. The project will also pay attention to the public image of these researches in the public sphere, in relation to the campaign “Atoms for Peace” and the development of nuclear industry in Europe. In doing so, the project will develop new historiographical techniques related to the use of the press as a source in the history of science.