China plans 'brightest light' to decode microworld

BEIJING -- China will start building the world's brightest synchrotron radiation light source by the end of this year in Beijing, hoping to help scientists better study the structure of microscopic particles.

The High Energy Photon Source (HEPS), also called "Beijing light source" in Chinese, is expected to produce X-rays up to 300 keV in photon energy, according to the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences (CAS), which is in charge of the development of the project.

A synchrotron radiation light source is a source of electronmagnetic radiation usually produced by a storage ring.

To generate light of extreme brilliance, electrons will be accelerated nearly to the speed of light in several stages and forced to travel in a closed path. Bending magnets and insertion devices in the storage ring will supply the strong magnetic fields to help convert high energy electrons into photons with high brilliance.

Construction of the HEPS will be finished in six and a half years and its first phase will cover about 65 hectares in Beijing's suburban Huairou district. It will consist of accelerator chains, 14 beamlines and other auxiliary facilities.

The accelerator chains include a linear accelerator, a booster and a gigantic storage ring with a circumference up to about 1,360 meters.

The storage ring is considered key to the generation of "brightest light," as it will effectively lower the emittance down to 60 pm rad or lower, according to a scientific paper published in Chinese Physics C.

The lower the emittance, the brighter the synchrotron light.

"The emittance is minimized to enable many more photons of a given direction to be concentrated on a spot per unit of time, which will determine the light brilliance," explained Xu Gang, the paper's first author.

The X-rays produced by such a light source will help open a new door in observing and studying matter at the micrometer to nanometer level, Xu said.

Scientists use different light to study different things. For example, they observe stars with radio waves, follow airplanes with microwaves, and study very small objects, like viruses, protein molecules and metal atoms, with the light that is close to the size of these particles in wavelength.

"How does a blood cell flow in a vessel? How does a scientific device at the nanometer level work? How do we inject and extract lithium ions from batteries? All the studies rely on light with extremely short wavelengths, or in other words, extremely bright light," said Ding Hong, a researcher in the Institute of Physics of CAS.

In the future, HEPS will serve as a research platform for material science, chemical engineering, biomedicine and other fields.