China Builds Brightest “X-ray Machine”, 90 Soccer Fields Size

A peek inside the world's most powerful X-ray machine and its potential to revolutionize science

July 4, 2024
Editor-in-Chief, The China Academy
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In the bustling heart of Beijing’s Huairou Science City, a marvel of human ingenuity is taking shape – the world’s most radiant beacon of light is being erected. This awe-inspiring edifice, akin to a titanic X-ray machine of unparalleled scale, promises to pierce the veil of the infinitesimal realm, casting illumination upon the unseen microcosm.

This prodigious instrument will bestow upon us the power to scrutinize the minute world in all its dimensions, rendering visible the concealed microstructures of matter in real-time, and in-situ. It will unravel the enigmatic processes that orchestrate the birth and evolution of these microscopic formations, effectively conducting an exhaustive “health audit” on the very fabric of existence.

It is China’s first fourth-generation synchrotron radiation source – the High Energy Photon Source (HEPS), aptly nicknamed the “Light of Hope.”

A significant milestone was reached on July 1st when the HEPS storage ring completed its full-ring vacuum closed loop in Beijing. This achievement marks the full connection of the storage ring and its transition into the commissioning phase.

The HEPS storage ring boasts an impressive beam orbit circumference of approximately 1360.4 meters. It’s designed to store high-energy, high-quality electron beams while generating synchrotron radiation. This makes it the third-largest light source accelerator globally and the largest in China. The ring employs a sophisticated 48-period seven-bend achromat magnetic focusing structure, achieving a horizontal natural emittance better than 60 pm·rad at 6 billion electron volts.

From an aerial perspective, the HEPS facility comprises three main buildings, forming a shape reminiscent of a magnifying glass – a fitting symbol for its role in detecting the microscopic world. The comprehensive experimental building and user service building constitute the “handle,” while the largest circular structure houses the light source devices, representing the “frame” of this metaphorical magnifying glass.

This circular building is the heart of the HEPS. Inside this main building, several critical components are housed: electron injectors (including a linear accelerator and booster), the electron storage ring, and beamlines. The facility’s operation begins with an electron gun producing high-quality electron beams. These are accelerated to 0.5GeV by the linear accelerator before being injected into a 450-meter circumference ring booster, which further increases their energy to the rated 6GeV. At this point, the electron beam approaches the speed of light and is injected into the larger 1360-meter circumference storage ring. As the electron beam passes through bending magnets or insertion devices at various points in the storage ring, it emits stable, high-energy, high-brightness synchrotron radiation along the tangential direction of its deflected path.

Just as medical X-rays can reveal bones beneath skin and clothing, the HEPS’s light beam can penetrate matter, performing three-dimensional scans deep inside materials and observing spatiotemporal changes at molecular and atomic scales.

X-rays serve as probes for detecting material structures, with higher brightness allowing for clearer visualization of internal microstructures. Since Wilhelm Röntgen’s discovery of X-rays over a century ago, scientists have continually innovated to produce X-rays with higher energy and stronger brightness. Synchrotron radiation sources represent a significant advancement in this pursuit.

Synchrotron radiation is produced when charged particles moving near light speed undergo curved motion, emitting electromagnetic radiation along the tangential direction. This phenomenon can be visualized as water droplets flying off a rapidly rotating umbrella during rainfall. Compared to conventional X-rays, synchrotron radiation offers several advantages: a wider spectrum (covering infrared, visible, ultraviolet, and X-ray bands), higher brightness (4 to 14 orders of magnitude greater than conventional X-ray machines), better coherence, and improved collimation. These properties enable high-penetration, high spatiotemporal resolution experiments.

China has consistently prioritized the development of synchrotron radiation sources. The country has already built three generations of such facilities: the Beijing Synchrotron Radiation Facility (1989), the Hefei Synchrotron Radiation Source (1990), and the Shanghai Synchrotron Radiation Facility (2009). These facilities have facilitated numerous significant scientific breakthroughs.

The HEPS represents China’s first foray into high-energy synchrotron radiation sources, filling a crucial gap in the nation’s scientific infrastructure. It will stand as one of the world’s brightest fourth-generation synchrotron radiation sources.

The HEPS storage ring’s 6GeV electron energy enables it to provide high-energy X-rays of 300keV. Its design, featuring 48 multi-bend achromat units, results in lower electron emittance and brightness 100 times higher than third-generation sources – a staggering 1 million times brighter than the sun. This incredible brightness allows X-rays to be focused to nanoscale dimensions, providing unprecedented clarity in understanding the internal structures of matter.

As this extraordinary facility nears completion, it promises to usher in a new era of scientific discovery, offering researchers unparalleled tools to explore the microscopic world and unlock the secrets of matter itself. It will enable in-situ observation of single crystal growth, shedding light on the mechanisms behind formation of defects in sheets and isotopic-to-columnar transitions. Engineering materials will benefit from full lifecycle, multi-scale characterization under HEPS. Failure factors during both manufacture and service can be explored in-depth.

In the medical domain, interpreting functions of critical proteins may help accelerate drug discovery. Essentially, everything from jet engines to viral proteins will be amenable to “checkups” using HEPS’ powerful examination abilities. Subtle issues like impurities or cracks invisible to the naked eye will be readily detectable.

Where other techniques fall short, HEPS promises to reveal problem areas comprehensively. Its cutting-edge imaging and analysis capabilities are poised to advance scientific understanding and industrial practices across a wide range of domains.


Editor-in-Chief, The China Academy
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