Complex scientific questions often require collaboration between scientists to access scientific instruments (deS. Price, Res Policy 13:3–20, 1984; Shrum et al. 2007, Structures of scientific collaboration, The MIT Press, 2007), knowledge and social capital from scientists outside of their immediate networks (Burt, Am J Sociol 110:349–399, 2004; Collins, Tacit and explicit knowledge, University of Chicago Press, https://press.uchicago.edu/ucp/books/book/chicago/T/bo8461024.html, 2012; Granovetter, Am J Sociol 78:1360–1380, 1973; Polanyi, Personal knowledge: towards a post-critical philosophy (Repr. (with corr.)). Routledge & Kegan Paul, 1962). Synchrotron radiation facilities are a unique case to explore this type of collaboration, as external scientists going to the facility to do their ordinary research work are common. These external users use complex scientific instrumentation that could require the additional accumulated knowledge of internal scientists and staff more familiar with the technical and social aspects of the instruments. These collaborations sometimes result in a co-authored publication with internal staff, employed in these facilities. However, this is not always the case. Data from the European Synchrotron Radiation Facility (ESRF) shows that most often, external scientists do not include internal staff in the co-author fields of the subsequent publication from scientific work done in one (or more) instruments in these facilities. Instrument collaboration networks are constructed and analysed over the period 2000–2018 for the different scientific instruments within the facility. A strong relationship between the level of external collaboration and the structure of the networks is found and explored. The results provide further insight into factors that shape collaboration and knowledge transfer, also relevant to policy makers and facility managers seeking to promote these activities.