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The European XFEL - a giant camera for reacting atoms

An unusual X-ray machine begins operating in northern Germany in September. The XFEL shoots extremely short and highly energetic flashes onto an object, filming atoms as they chemically react.

Deutchland Eröffnungszeremonie zum Start des Röntgenlasers XFEL (picture-alliance/dpa/C. Gateau)

Artists created a laser-beam installation above the European XFEl to celebrate the beginning of operations.

It sounds like science fiction - an X-ray camera that is not only detailed enough to capture pictures of individual atoms but that can even document the course of chemical reactions as they are happening.

Such a facility begins operations on September 1st, 2017 in Germany, calling itself the X-Ray Free-Electron Laser (XFEL).

The plant's incredible, atomic-level abilities requires something quite huge in terms of construction: The giant apparatus capturing tiny molecules measures more than 3.4 kilometers (roughly two miles), going all the way from the German Electron Sychrotron (DESY) in Hamburg to Schenefeld in the state of Schleswig-Holstein.

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A huge movie camera for atoms and molecules: the European XFEL

A huge variety of experiments

In the beginning, the X-ray laser will provide light for two laboratories. Over time, the number of these labs will gradually increase. Seven pipes will deliver rays to different labs, with each of those pipes appearing somewhat like a water pipe. Inside is an X-ray laser beam - a special kind of light source that makes it possible to shoot three-dimensional pictures of atoms.

The laboratories offer researchers possibilities that unknown thus far. Materials scientists can investigate the properties of nano materials. Physicists can expose matter to extreme pressures and temperatures and find out how it reacts under high energy density. They can create conditions like those in the early stages of our universe. Or they can use highly precise spectrometry to solve other questions. 

Biochemists and medical researchers can take a close look at biomolecules: What, exactly, do the three-dimensional structures of cells look like? They can also use the imaging to decipher the molecular structure of viruses.

Deutschland Forschungsanlage European XFEL (European XFEL)

The electrons are accelerated over 1.7 kilometers to reach nearly the speed of light.

Extremely short, extremely bright

The X-ray flashes coming out of the machine take only about 0.00000000000001 seconds, or ten femtoseconds. There are 27,000 such flashes every second. Their wavelength is extremely short: 0.005 to 4.7 nanometers. That's enough to provide images of atoms in detail.

The incredibly high number of pictures per second in turn makes it possible to take slides of chemical reactions while they are still taking place. Up to this point that had been totally unthinkable: Chemistry, as we know it, is based entirely on the idea that we look at a a substance before and after the chemical reaction. Then, using our understanding of physics and mathematics, we try to understand what probably happened to atoms and molecules in between. Now, chemists can observe this firsthand. They can create movies of chemical reactions.

Furthermore, the X-ray laser is considerably brighter than anything comparable. During its peaks, the XFEL reaches a brilliance of about one billion times higher than that of any other common X-ray. Even at its average setting it is still about ten thousand times more powerful.

Deutschland Forschungsanlage European XFEL (DESY 1999)

Special superconducting microwave chambers are used inside the accelerator.

Several kilometers of tunnel

The X-ray flashes consist of special pulsed packages of electrons. A pulsed laser produces the electrons by hitting a metal target. Then, the particles travel through an acceleration track 1.7 kilometers long.

The linear accelerator consists of superconducting chambers, inside of which a microwave oscillates and pushes the particles to almost the speed of light. The chambers are cooled down to minus 271 degrees Celsius to enable electrical current in the plant to flow without resistance. All of thise takes place inside a tunnel between 15 and 38 meters underground.

At an energy of up to 17.5 billion electron volts, the electrons first reach a redistribution station, where they are split up into different pipes. That's to make them available to a large number of scientists, who can then use them for experiments in different labs. At the end of the track, they reach the research campus in Schenefeld after 3.4 kilometers.

Built by Europeans for all scientists

Scientists are eagerly waiting to start projects at the new facility, which they have been preparing for years. The first two groups of researchers who' ve gotten access to the labs include a team around Australia' s Anton Barty. He hopes to take pictures of biomolecules. The other group, led by Polish researcher Wojciech Gawelda, aims to film chemical reactions. Both work at the DESY. British and Russian scientists have also reserved research time.

XFEL is a Europe-wide research project. Germany covers 58 percent of the costs and Russia 27 percent. Denmark, France, Italy, Poland, Sweden, Switzerland, Slovakia, Spain and Hungary also take part, with each covering between one and three percent of the costs.

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