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Title
X-ray lasers and crystallography
Description
The invention of the laser in the 1950 s for visible light and microwaves, and the slow but steady recognition of its manifold uses, is a truly remarkable story in the history of science. But the severe λ[superscript 3] dependence of the ratio of stimulated (mostly coherent) to spontaneous (incoherent) emission meant that efforts to build an X-ray laser seemed hopeless for decades. As so often happens in the history of science, the breakthrough eventually occurred at the interface of several fields – synchrotron science (and especially their insertion devices), laser physics, and work on microwave tubes for radar, emerging from the second world war. Synchrotrons themselves were an outgrowth of the particle accelerators of nuclear physics, whose X-ray radiation was considered a nuisance. All of this culminated recently in the construction of the first hard-X-ray laser, the US Department of Energy's Linac Coherent Light Source (LCLS), at their SLAC laboratory near Stanford. The first X-ray lasing occurred in that two-mile long tunnel on April 21, 2009, at about 2 kV, in an all-or-nothing moment of intense excitement, as theoretical predictions proved spot-on. The new laser principle needed for hard-X-ray lasing, the free-electron laser (FEL), was first demonstrated in the infra-red region at Stanford in 1975 in John Madey's group, following earlier theoretical work by Motz and Phillips on microwave tubes. Other FELs soon followed, in the microwave and visible region, leading to the LCLS. The XFEL method provides brief pulses of X-ray laser radiation by the SASE (self-amplified spontaneous emission) process, using a resonant undulator driven by a LINAC electron accelerator. Each LCLS pulse, of 10 fs duration (repeated 120 times a second) contains about 10[superscript 12] hard-X-ray photons, about the same number that a synchrotron might generate in a second.
Date Created
2014-04-30
Contributors
- Spence, John (Author)
- College of Liberal Arts and Sciences (Contributor)
- Department of Physics (Contributor)
Resource Type
Extent
2 pages
Language
eng
Copyright Statement
In Copyright
Primary Member of
Identifier
Digital object identifier: 10.1107/S2052252514009567
Identifier Type
International standard serial number
Identifier Value
2052-2525
Series
IUCrJ
Handle
https://hdl.handle.net/2286/R.I.45181
Preferred Citation
Spence, J. C. (2014). X-ray lasers and crystallography. IUCrJ, 1(3), 151-152. doi:10.1107/s2052252514009567
Level of coding
minimal
Cataloging Standards
Note
View the article as published at http://journals.iucr.org/m/issues/2014/03/00/hi0131/index.html
System Created
- 2017-08-18 02:38:43
System Modified
- 2021-08-16 02:23:30
- 3 years 3 months ago
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