ELETTRA, the synchrotron light source on the outskirts of Trieste in Italy, shares with its sister facility ALS in California the world record for brightness in the spectral domain of 'soft' X-rays. Commissioned in 1993 under the leadership of the Physics Nobel laureate Carlo Rubbia, ELETTRA is, basically, a storage ring for electrons, an ultra-high-vacuum tube in which electrons circulate along a nearly-circular trajectory. The electrons interact with different types of magnetic devices which force them to emit X-rays. The electrons circulate at a speed close to that of light, therefore are subject to the laws of Albert Einstein's relativity. ELETTRA, therefore, puts relativity at work to produce X-rays of superior quality. The emitted X-rays are collected by beamlines which depart from the main ring and are terminated by experimental chambers designed for a wide variety of applications. The X-ray wavelength for each beamline can be controlled and modified over a very wide spectral range. This is a marked advantage over the fixed wavelength of conventional X-ray sources: the wavelength can be optimised for each specific application. Furthermore, one can implement techniques that require wavelength-scanning, most notably for chemical analysis.
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