The 7th FELs of Europe PhotonDiag conference took place in Liverpool, UK from 2nd to 4th September 2025. PhotonDiag is the première conference focused on the technical aspects of photon delivery to science experiments on advanced, accelerator-based photon sources and free-electron laser (FEL) sources in particular. It covers the thematic areas of photon diagnostics, photon beamlines and optics, photon detectors and computational techniques associated with these areas. 

The conference was organised by the Accelerator Science and Technology Centre (ASTeC) of UKRI-STFC Daresbury Laboratory in conjunction with Diamond Light Source. It was hosted by Liverpool University in the excellent facilities of the Guild of Students. The attractive location is at the heart of Liverpool and opposite the landmark of Liverpool Metropolitan Cathedral. The event was sponsored by Axilon AG, Strumenti Scientifici Cinel S.r.l, JJ X-ray, Omniscan Ltd and XDS Oxford Ltd. 

Over the three days of the conference, the 68 delegates enjoyed a wide-ranging set of talks and posters. In total, there were 13 invited talks, 24 contributed talks and 20 posters. An important part of the conference is the opportunity for experts to interact with each other, exchanging ideas and fostering collaborative solutions to the complex challenges presented by todays and tomorrows advanced photon sources. Despite the busy talk schedule, there was plenty of time to talk over refreshment breaks whilst enjoying the excellent catering provided by the University. The conference dinner took place in the historic setting of the Victoria Gallery and Museum on the evening of the 3rd, a venue that garnered much appreciation.

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