The Advanced Photon Source (APS) at Argonne National Laboratory is a storage-ring-based high-energy X-ray light source facility. It is one of five X-ray light sources owned and funded by the U.S. Department of Energy Office of Science. The APS began operation on March 26, 1995. It is operated as a user facility, meaning that it is open to the world’s scientific community, and more than 5,500 researchers make use of its resources each year.

Argonne National Laboratory is a federally funded research and development center in Lemont, Illinois, United States. Founded in 1946, the laboratory is owned by the United States Department of Energy and administered by UChicago Argonne LLC of the University of Chicago. The facility is the largest national laboratory in the Midwest.