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Building on the success of the world’s most powerful X-ray laser—the Linac Coherent Light Source (LCLS)—SLAC National Accelerator Laboratory is planning an upgrade that will keep the United States at the forefront of X-ray science.
Funded by the Department of Energy Office of Science, LCLS has been a spectacular success, consistently exceeding goals and expectations. Its highly focused beam arrives in strobe-like pulses just a few millionths of a billionth of a second long. This allows researchers to take crisp pictures of atomic motion and changes in chemical bonds, shedding light on the fundamental processes of chemistry, technology and life itself.
LCLS-II will add two new X-ray laser beams and room for additional new instruments, greatly increasing the number of experiments carried out each year. Its new capabilities will allow scientists to do important research that cannot be done anywhere today, including work in drug development, energy science and advanced materials.

​A Unique Tool

LCLS-II will enhance an LCLS research program that is already:

  • Increasing our understanding of chemistry to build better catalysts, which are used in 90% of all commercially produced chemical products including petroleum and biodiesel, pharmaceuticals and processed foods.
  • Exploring fundamental speed limits to build faster electronic devices.
  • Exposing the secrets—and vulnerabilities—of viruses, microbes and living cells.
  • Discovering new ways to decipher the structures of proteins involved in disease and its treatment.
  • Allowing direct observations of natural processes that convert sunlight into useable energy.

Increasing Capacity

The LCLS is in such high demand that only one out of four experimental proposals can be approved. Meanwhile, other countries are building similar X-ray lasers: Japan (operation began in 2012), South Korea (~2014), Germany (~2015) and Switzerland (~2016). Upgrades are critical for LCLS to stay in the forefront. By adding experimental stations and allowing several experiments to run at once, LCLS-II will increase the number of experiments run per year. Long-term plans call for additional expansion through 2025, accommodating up to 2,000 scientists per year at up to a dozen experimental stations.

Adding Research Capabilities

LCLS-II will provide an expanded range of X-ray wavelengths, allowing researchers to home in on carbon atoms involved in biological processes, peer inside thick three-dimensional materials and see intricate details of nanocrystal structures. It will set the stage for increasing the intensity of the X-ray laser beams 20-fold. In addition, researchers will be able to control the polarization of X-rays and whittle the pulse length down to about 1 femtosecond – one millionth of a billionth of a second.


Current plans call for defining the project’s cost and schedule and starting construction of the LCLS-II Injector Complex in 2012. FY 2013 would see construction start on undulators and technical hardware and the awarding of a contract for tunnel construction. Projected start of operations in 2019.



Artist’s conception of an atomic X-ray Laser
Artists conception of an atomic X-ray Laser 
Single pulse diffraction and structure of lysozyme
Single pulse diffraction and structure of lysozyme
Structure changes from an intense light pulse probed by LCLS
Structure changes from an intense light pulse probed by LCLS 

SLAC SLAC National Accelerator Laboratory, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy