Demonstration of self-seeding in a hard-X-ray free-electron laser
Abstract
The Linac Coherent Light Source (LCLS) is an X-ray free-electron laser at the SLAC National Accelerator Laboratory, which has been operating since 2009 for a wide range of scientific research. The free-electron laser process at LCLS is based on self-amplified spontaneous emission (SASE) where spontaneous emission from the initial electron beam shot noise is amplified by its interaction with the electrons over a long magnetic undulator. Although SASE is very effective, producing tremendously powerful, ultrashort X-ray beams, the start-up from noise leaves poor temporal coherence and a broad, noisy spectrum. We present experimental results of a new method, suggested by colleagues at DESY, allowing self-seeding using X-rays from the first half of the undulator to seed the second half through a diamond-based monochromator, producing near Fourier-transform-limited X-ray pulses with 0.4-0.5 eV bandwidth at 8-9 keV. These results demonstrate self-seeding at ångstrom wavelengths with a relative bandwidth reduction of 40-50 with respect to SASE.
- Publication:
-
Nature Photonics
- Pub Date:
- October 2012
- DOI:
- 10.1038/nphoton.2012.180
- Bibcode:
- 2012NaPho...6..693A