A new facility at the U.S. Department of Energy’s SLAC National Accelerator Laboratory will combine a petawatt laser system with an x-ray free-electron laser (XFEL) to further the scientific understanding of matter in extreme conditions. Coupled to the lab’s Linac Coherent Light Source (LCLS), the Matter in Extreme Conditions Upgrade (MEC-U) received approval from the DOE Office of Science to move from its conceptual design phase to preliminary design and execution, having passed what is known as Critical Decision 1. “It’s been gratifying to see the community rally together to support this project, and I think this achievement really validates those efforts. It shows that this notion of locating high-energy lasers next to an XFEL can now be realized,” said SLAC scientist Arianna Gleason. “Working in concert, they’ll allow us to look behind the curtain of physics at extreme conditions to see how it’s all stitched together, opening a new frontier.” In a new underground experimental facility coupled to SLAC’s Linac Coherent Light Source, two state-of-the-art laser systems — a high-power petawatt laser and a high-energy kilojoule laser — will feed into two new experimental areas dedicated to the study of hot dense plasmas, astrophysics, and planetary science. Courtesy of Gilliss Dyer, SLAC National Accelerator Laboratory. SLAC will work in partnership with Lawrence Livermore National Laboratory and the University of Rochester’s Laboratory for Laser Energetics to design and construct the facility in a new underground cavern. There, two state-of-the-art laser systems — a high-power petawatt laser and a high-energy kilojoule laser — will feed into two new experimental areas dedicated to the study of hot dense plasmas, astrophysics, and planetary science. “Not only are we working with some of the leading laser laboratories in the world, but we’re also working with world experts in the experimental science, high-energy density science, and the operation of DOE Office of Science user facilities where scientists from all over the world can come to do experiments,” said Alan Fry, MEC-U project director. The project builds on the success achieved at the existing Matter in Extreme Conditions instrument at LCLS. Funded by the DOE Office of Science’s Fusion Energy Sciences program, MEC uses short-pulse lasers coupled to x-ray laser pulses from LCLS to precisely probe the characteristics of matter. “The new high-power lasers being designed by Livermore and Rochester are world-leading in their own right,” Fry said. “The fact that they’re coupled to LCLS then really puts it over the top in terms of capabilities.” MEC-U will also take advantage of the LCLS-II upgrade to the LCLS facility, which will provide x-ray laser beams of unsurpassed brilliance for probing those plasmas, doubling the x-ray energy that has been attainable to date. Access to the facility will be open to researchers from across the country and around the world, facilitated in part by LaserNetUS, a research network aimed at boosting access to high-intensity laser facilities at labs and universities across the country.