User Community Dynamics at a Large-Scale Research Infrastructure: Comparative Insights from Two Cases at the SOLEIL Synchrotron

This article analyzes the role of large-scale Research Infrastructures (RIs) in structuring the scientific landscape through the study of the dynamics of their academic user communities. We adopt a qualitative, meso-level approach to understand how an RI influences the emergence and evolution of scientific collectives. The study relies on a comparative analysis of two cases at the SOLEIL synchrotron facility: the biomedical sciences user community and the quantum materials user community. Drawing on a theoretical framework built from the literature on the social and scientific impacts of RIs, as well as on communities of practice and social networks, the analysis reveals two contrasted dynamics of community development. The biomedical community, which is emerging, is characterized by high heterogeneity, weak ties, and an individual mode of instrument appropriation that relies on boundary spanners to bridge the gap between the clinical world and the research infrastructure. In contrast, the quantum materials community, which is more mature, exhibits a collective mode of appropriation marked by strong ties, high visibility, and the integration of RI scientists as full scientific peers. These results highlight two distinct trajectories in the structuring of scientific communities around a large-scale instrument: the convergence of pre-existing disciplines on the one hand, and, on the other, the emergence of a new specialized branch within an established scientific community through the progressive specialization of some of its members.