World’s Most Intense X-Ray Laser Focuses on Livermore Science
THE Linac Coherent Light Source, or LCLS, is the brightest x-ray source in the world and the first x-ray laser available for use by scientists worldwide. It is also the most significant scientific facility built to date in the new millennium by the Department of Energy’s Office of Science.
As described in the article Groundbreaking Science with the World’s Brightest X Rays, Livermore scientists are leaders in applying this unique instrument. Using its unprecedented spatial and temporal resolution, they are studying the most fundamental processes that occur in materials and for the first time are capturing atoms and molecules in motion. The Laboratory has been interested in developing x-ray lasers for several decades. In 1984, scientists demonstrated the world’s first laboratory x-ray laser on Livermore’s two-beam Novette laser, and in 1996, they built the tabletop COMET x-ray laser at the Laboratory’s Jupiter Laser Facility.
Livermore has been closely involved with LCLS since its conception. Our involvement began with an experiment at Brookhaven National Laboratory called VISA, which in 2001 demonstrated the feasibility of a process called self-amplified spontaneous emission (SASE), the basis of LCLS’s extraordinarily bright and coherent x-ray pulses. The experiment’s success contributed to the decision by the Energy Department to build the $420 million LCLS at the SLAC National Accelerator Laboratory in Menlo Park, California.
During the LCLS research and development phase, Livermore invested Laboratory Directed Research and Development funds toward showing that x-ray optics could be built to withstand the intense x-ray fluences LCLS would generate. During construction, we partnered with SLAC and Argonne National Laboratory to complete the project on time and within budget. Following the facility’s commissioning, Livermore researchers began an experimental program to explore the behavior of materials under extreme conditions of temperature and pressure. Our researchers have been among the most successful competitors for beam time on LCLS and have led and collaborated on a number of pioneering experiments conducted with partners from universities and research centers in the U.S. and Europe.
Our experimental program focuses on three broad categories. First, we are advancing the field of x-ray quantum electronics. Experiments led by Nina Rohringer are demonstrating the ability of the main LCLS beam to “pump” a secondary x-ray beam of greater coherence using a gaseous target. Second, in experiments led by Stefan Hau-Riege, we are advancing materials science by studying the damage caused by intense x-ray pulses. Finally, we are imaging biomolecules such as proteins and viruses. These experiments, led by Henry Chapman of the University of Hamburg (formerly of Livermore) and Matthias Frank, are developing the methods for precise injection of biomolecules. The work is a step toward unraveling the structure and operation of membrane proteins that control the cellular exchange of chemicals with the environment. Successful imaging will benefit fields ranging from human health to bioenergy.
The ability of LCLS to examine the physical processes in materials under extreme conditions is directly relevant to the Laboratory’s national security mission, in particular its stockpile stewardship responsibilities, where understanding the response of materials to high pressures and temperatures is critical to predicting how nuclear explosives function. LCLS also offers a complementary capability to experiments conducted on the National Ignition Facility, the world’s most energetic laser and the center of Livermore’s high-energy-density research.
Lessons learned at LCLS will benefit x-ray lasers now being planned in Europe and Japan. LCLS is the second large facility using SASE. The first was the free-electron laser FLASH developed at the Deutsches Elektronen-Synchrotron in Hamburg, Germany, which generates extreme ultraviolet photons. Many Livermore experiments being conducted on LCLS were first demonstrated on FLASH, which is scheduled for an upgrade to an x-ray laser source similar to LCLS. Working on this new generation of x-ray sources, Laboratory scientists will continue to push the frontiers of science and enhance our nuclear security.