UNL Researchers Use Compact Laser to Generate Synchrotron X-Rays
3 December 2013
A research team at the University of Nebraska-Lincoln (UNL) has demonstrated an innovative method to produce synchrotron X-rays by deploying a "tabletop" but powerful laser, the university has reported on its website.
Synchrotron X-rays are perfect for a broad range of research purposes, from examining the structure of matter to advanced medical images, but so far access to the technology has been restricted since most devices are too big and expensive and they can be found only in a small number of sites across the globe.
In conventional synchrotron devices, electrons are accelerated to exceptionally high energy and then confined to change direction periodically and release energy at X-ray wavelength with the help of magnets. For their experiment, detailed in the journal Nature Photonics, the researchers at UNL's Extreme Light Laboratory used laser light to replace both the electron accelerator and the magnets. The team first directed their laser beam to a gas jet, producing a beam of relativistic electrons. Another beam was then focused on to the accelerated electron beam, causing a rapid vibration and making the electrons emit a bright burst of synchrotron X-rays. During this process, called Compton scattering, the light's photon energy was boosted by a million-fold but still the overall length of the accelerator and synchrotron was smaller than the size of a dime.
Compact lasers have been applied for generating X-rays in the past, but they didn't have some of the characteristics peculiar to synchrotron light, like the relatively pure and tunable color spectrum, and rather resembled the 'white light' released by the sun, the lab's director and project leader Donald Umstadter said. This new device generates X-rays over a much broader range of photon energies, extending even to the energy range of nuclear gamma rays, he added.