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SLAC Fact Sheet: The Linac Coherent Light Source

World's first hard X-ray free-electron laser achieves first light, April 2009

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SLAC National Accelerator Laboratory is home to a two-mile linear accelerator—the longest in the world. Originally a particle physics research center, SLAC is now a multipurpose laboratory for astrophysics, photon science, accelerator and particle physics research. (Click on image for larger version.)

The Linac Coherent Light Source is the world's first hard X-ray free-electron laser, located at the U.S. Department of Energy's SLAC National Accelerator Laboratory in Menlo Park, California. SLAC is operated by Stanford University for the DOE. The LCLS produced its first laser light in April 2009.


The LCLS will open scientific frontiers as a first-in-kind lightsource.

  • The Linac Coherent Light Source generates X-ray laser pulses of unprecedented energy, record-shattering brilliance and ultrashort duration, enabling frontier research into the structure of materials and the processes of chemistry and life.
  • The LCLS is the first free-electron laser capable of producing hard X-rays—those at the high-energy, short-wavelength end of the X-ray spectrum. With wavelengths smaller than single molecules, X-rays are ideal for imaging at the tiny scale of atoms and molecules.
  • At its full potential, the LCLS will produce ultrashort X-ray pulses more than a billion times brighter than any previous source—powerful enough to make images of single molecules.
  • The LCLS will provide 10 trillion X-ray photons in a flash of about 100 femtoseconds—a quadrillion times more efficient than today's best storage-ring-based synchrotron lightsources.
  • The LCLS X-ray pulses will be extremely brief, allowing this unique laser to work much like a high-speed camera. The LCLS X-ray flash will provide an unprecedented "shutter speed" of less than 100 femtoseconds—about the time it takes light to travel the width of a human hair—making is possible to capture images of chemical and biological processes in action.
  • The LCLS is more than a mile long, and its undulator hall will soon include 33 undulator magnets with a total of about 3000 alternating north–south poles.


Several Department of Energy laboratories and U.S. universities made significant contributions to the LCLS project.

  • Argonne National Laboratory oversaw the design and fabrication of the full LCLS undulator system; the magnets within these undulators were precision tuned, installed and aligned by SLAC teams. Together, SLAC and Argonne scientists created the monitoring and positioning systems that keep the electron beam on target with great precision.
  • A suite of diagnostic, focusing and transport equipment, designed at Lawrence Livermore National Laboratory, is currently being installed. This equipment will measure and optimize the LCLS X-ray beam.
  • Cornell University designed and constructed a unique pixel array detector that is capable of capturing and storing images extremely quickly.
  • Additional technical contributions were made by Lawrence Berkeley National Laboratory, which provided a fiber-optic based system to carry timing information from the linear accelerator to the experimental halls; and UCLA, which provided research and development support in understanding the physics of free-electron lasers.
  • In addition, Pacific Northwest National Laboratory provided additional project management which helped make this project successful.

LCLS Instruments

A suite of X-ray instruments for exploiting the unique scientific capability of the LCLS will be built at SLAC. Each instrument will have unique capabilities, creating a diverse experimental landscape for probing ultrafast dynamics. A short introduction to each instrument follows.

  • The Atomic, Molecular and Optical science instrument will enable the study of the interaction between the extremely intense LCLS X-ray pulses and the basic constituents of matter: atoms and molecules.
  • The X-ray Pump Probe science instrument will predominantly use a fast optical laser to generate rapid changes in matter, and the hard X-ray pulse from the LCLS to probe the structural dynamics initiated by the laser excitation.
  • The X-ray Correlation Spectroscopy instrument will observe dynamical changes of large groups of atoms in condensed matter systems over a wide range of time scales.
  • The Coherent X-ray Imaging instrument will take advantage of the extremely bright, ultrashort LCLS pulses of hard X-rays to allow imaging of non-periodic nanoscale objects, including single or small clusters of biomolecules at or near atomic resolution.
  • The Soft X-ray Materials Science beamline will enable the high brightness and timing capability of the LCLS to be applied to scattering and imaging experiments that require the use of soft X-rays.
  • The proposed sixth and final LCLS instrument will allow researchers to create and probe matter at temperatures exceeding 10,000 Kelvin and at pressures 10 million times the earth's atmospheric pressure at sea-level. The Matter in Extreme Conditions instrument would use both the LCLS's ultra-bright, ultra-short X-ray pulses and powerful optical lasers to enable unprecedented understanding of exotic states of matter otherwise only found at the cores of giant planets.

LCLS Background

Previous news leading up to the LCLS first light:


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