Tabletop Source of Bright, Coherent Synchrotron X-Rays Developed

Generating closely focused beams of high energy X-rays, to study everything from molecular structures to the integrity of aircraft wings, could become easier and less expensive according to new research.

On October 27, 2010, in the journal Nature Physics, researchers from Imperial College London (UK), the University of Michigan (Ann Arbor, USA), and Instituto Superior Téchnico Lisbon (Portugal) described a tabletop instrument that generates synchrotron X-rays, whose energy and quality rivals that produced by some of the largest X-ray facilities in the world.

Scientific and medical developments frequently depend on the development of better diagnostic and analytic tools, to enable more and more precise investigations at higher and higher resolutions. The development and use of high-energy light sources to examine the details of a wide range of compounds for research and commercial purposes is a rapidly growing area of science and engineering. However, high power, high quality X-ray sources are typically very large and very expensive. For example, the Diamond Light Source synchrotron facility in Didcot, UK, is 0.5 km in circumference and cost US$421 million to build.

The researchers behind this study have shown that they can replicate much of what these huge machines do, but on a tabletop. Their microscale system uses a tiny jet of helium gas and a high power laser to produce an ultrashort, pencil-thin beam of high energy and spatially coherent X-rays.

"This is a very exciting development,” said Dr. Stefan Kneip, lead author on the study from the department of physics at Imperial College London. "We have taken the first steps to making it much easier and cheaper to produce very high energy, high quality X-rays. Extraordinarily, the inherent properties of our relatively simple system generates, in a few millimeters, a high quality X-ray beam that rivals beams produced from synchrotron sources that are hundreds of meters long. Although our technique will not now directly compete with the few large X-ray sources around the world, for some applications it will enable important measurements which have not been possible until now.”

The X-rays produced from the new system have an extremely short pulse length. They also originate from a small point in space, approximately 1 μm across, which results in a narrow X-ray beam that allows researchers to see fine details in their samples. These qualities are not readily available from other X-ray sources and so the researchers' system could increase access to, or create new opportunities in, advanced X-ray imaging. For example, ultrashort pulses allow researchers to measure atomic and molecular interactions that occur on the femtosecond timescale.

Dr. Zulfikar Najmudin, the lead investigator of the investigative team from the department of physics at Imperial College, added, "We think a system like ours could have many uses. For example, it could eventually increase dramatically the resolution of medical imaging systems using high energy X-rays, as well as enable microscopic cracks in aircraft engines to be observed more easily. It could also be developed for specific scientific applications where the ultrashort pulse of these X-rays could be used by researchers to ‘freeze' motion on unprecedented short timescales.”

Related Links:
Imperial College London
University of Michigan
Instituto Superior Téchnico Lisbon