Argonne National Laboratory has received approval from the U.S. Department of Energy (DOE) for the next phase of the $815 million upgrade of the Advanced Photon Source (APS). The Critical Decision 3 milestone approves the project’s final design for the upgrade and authorizes the laboratory to begin procurement and construction. The upgrade, according to a release from the DOE, will position the APS as the nation’s brightest energy, storage-ring-based x-ray source. The upgrade will replace the APS storage ring and develop or update x-ray beamlines and other equipment creating the more powerful x-ray facility. The APS-U storage ring will feature a new design, a multibend achromat lattice with many more bending magnets and magnet-focusing cells than the present machine, resulting in brighter x-ray production. The APS works like a giant x-ray microscope, producing extremely bright, focused x-rays that look through dense materials and illuminate the structure and chemistry of matter at the molecular and atomic level. X-rays produced at APS’s current power level are up to one billion times brighter than those of an x-ray found in a typical dentist’s office. “This project will be a scientific game-changer,” said Robert Hettel, director of the APS upgrade project. “The APS upgrade will allow researchers to see things at a scale they have never seen before with storage-ring x-rays. We’ll be able to look deep inside real samples, such as biological organisms, and observe atoms moving in real time. Such extreme levels of detail will open new frontiers and discoveries in basic science and help solve pressing problems across a wide range of industries.” The upgrade is expected to increase the brightness of the APS by two to three orders of magnitude. Removal of the old storage ring and installation of the new one is planned to begin in June 2022. The installation and subsequent ring commissioning period will last for about one year, after which the upgraded APS’s x-ray beamlines will be brought online for researchers.