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New experimental tools and techniques open windows that allow scientists to peek into unexplored scientific realms and to test theoretical predictions. X-ray imaging is unique, both because of the penetrating power of x rays in solid matter—as Wilhelm Röntgen discovered in 1895—and because x-ray wavelengths are short enough to resolve the interatomic spacing in matter via diffraction—Max von Laue’s discovery in 1912. Those properties allow scientists to push forward fundamental physical sciences and to find major applications in structural imaging, from new commercial drugs to jet turbine blades.
The early success of the Linac Coherent Light Source (LCLS) has bolstered plans for more accelerator-based x-ray free-electron lasers (XFELs) in Europe and Asia. But the new machines create a challenge: The ultrabright femtosecond pulses generated by XFELs have properties far beyond previous sources. They carry a million times more pulse energy than synchrotron x rays, are 10 000 times shorter, and have coherence that can produce focused x-ray beams with intensities up to 1020 W/cm2, more than a billion times greater than any previously achieved. The XFELs demand new research methods that can take advantage of those characteristics.
Physics Today:
Brighter and faster: The promise and challenge of the x-ray free-electron laser
Philip H. Bucksbaum and Nora Berrah
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