SOLEIL ("Sun" in French) is a synchrotron facility near Paris, France.

It is located in Saint-Aubin in the Essonne département, a south-western suburb of Paris, near Gif-sur-Yvette and Saclay, which host other facilities for nuclear and particle physics.

[citation needed] The facility is an associate member of the University of Paris-Saclay.

[citation needed] SOLEIL also hosts IPANEMA, the European research platform on ancient materials (archaeology, palaeontology, past environments and cultural heritage), a joint CNRS / French Ministry of Culture and Communication research unit.

It takes the electrons 1.2 μs to travel around this ring at almost the speed of light; 847,000 times per second.