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First lasing and operation of an ångstrom-wavelength free-electron laser


The recently commissioned Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs (10−15 s). With these beam characteristics this light source is capable of imaging the structure and dynamics of matter at atomic size and timescales. The facility is now operating at X-ray wavelengths from 22 to 1.2 Å and is presently delivering this high-brilliance beam to a growing array of scientific researchers. We describe the operation and performance of this new ‘fourth-generation light source’.

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Figure 1: LCLS machine layout.
Figure 2: Photograph of a single undulator segment.
Figure 3: Electron trajectories through the undulator after beam-based alignment.
Figure 4: FEL gain length measurement at 1.5 Å.
Figure 5: Measured X-ray pulse energy (blue) and estimated peak power (green) versus FWHM electron bunch length.


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The authors would like to express their sincere thanks to the many people at SLAC, LLNL, ANL and UCLA who contributed to this project, including the accelerator operations group, the electron and X-ray systems controls groups, ANL undulator systems design, LLNL X-ray diagnostics/optics, RF engineering, mechanical design, metrology, precision magnetic measurements, power conversion and the dedicated machine maintenance groups. We also thank the LBNL timing and synchronization team and in particular H. Sinn and J. Gruenert of DESY and S. Zholents of LBNL for their appreciable help with FEL commissioning in the spring of 2009. We are also grateful for the support of the US Department of Energy, Office of Science, under contract no. DE-AC02-76SF005, and the sponsorship of the LCLS mission by the Office of Basic Energy Sciences.

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P.E., J.A., R.B., P.B., Z.H. and H.-D.N. co-wrote the paper. All authors designed, constructed and tested the accelerator and X-ray systems, performed experiments and analysed the data. J.G. was the LCLS project director.

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Correspondence to P. Emma.

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Emma, P., Akre, R., Arthur, J. et al. First lasing and operation of an ångstrom-wavelength free-electron laser. Nature Photon 4, 641–647 (2010).

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