The European XFEL x-ray laser: taking a look at unknown worlds
Germany recently became home to the world's largest x-ray laser, the European XFEL. The x-ray flashes generated in the 3.4 km long system of underground tunnels allow the tiniest particles and extremely fast processes to be studied with an unprecedented level of precision.
It is called photosynthesis and no one has ever seen it live before: how plants use sunlight to transform water into energy. If we were able to gain a better understanding of this process and to copy and optimise it, we would be able to revolutionise humankind's energy supply. The European XFEL, the largest x-ray laser in the world, might be able to do it. In September 2017, it went into operation near Hamburg.
The European XFEL is a research facility of superlatives: The x-ray laser's system of tunnels is 3.4 km long, running from the DESY campus in Hamburg-Bahrenfeld to the nearby town of Schenefeld in Schleswig-Holstein. Thirty-eight metres below ground, bunches of electrons are accelerated in an almost 2 km long vacuum tube to such a speed that they acquire 30 million volts of energy per metre, ultimately reaching an incredible 17.5 billion electron volts.
In Schenefeld, the electrons are directed on a slalom course through special arrangements of magnets, continuing along the tunnel to a mirror. When it hits the mirror, the electron beam has reached 99.99934 per cent of the speed of light. The level of radiation is so high by this point that the electron beam emits laser light.
Behind the mirror lies the x-ray laser's experiment hall, in which researchers work with the laser. The tunnel has already branched several times by then, thus generating the appropriate x-ray light for each of the various instruments in the hall.
The eye of the laser
The European XFEL generates 27,000 extremely short x-ray flashes per second. Conventional x-ray lasers have only managed considerably fewer so far: LCLS in the USA creates 120 pulses per second, while SCALA in Japan generates 60. The brilliance is also billions of times greater than that of the best x-ray radiation sources to date.
This requires the world's fastest x-ray detector to keep pace with the large number of x-ray flashes. The “eye” of the European XFEL is the Large Pixel Detector (LPD). It can record 4.5 million images per second, making it fast enough to take sharp shots or “molecular films” of ultra-fast processes such as photosynthesis.
What the European XFEL can do
Observing photosynthesis is just one example of all the things the European XFEL can do. Its x-ray flashes allow researchers to conduct a wide variety of experiments. Various measuring stations are available, equipped with different kinds of instruments. Scientists can not only observe dynamic, ultra-fast processes, but also study nanoparticles and extreme states of matter.
The extremely bright flashes also enable biomolecules to be studied more effectively and simply than ever before at atomic level. Even cells, viruses or other biological objects can be shown at a resolution of just a few nanometres.
This means that the European XFEL can show an unprecedented level of detail of the biomechanical and biochemical processes that the tiny HIV or influenza viruses use to infect cells, for example. It is hoped that this will allow effective treatments to be developed for these diseases.
Research is being conducted in a number of areas, usually at an international and interdisciplinary level. The main areas of research are:
- Materials science
- Energy technology
More than 60 research groups responded to a call for proposals by submitting applications for the research they would like to conduct using the giant x-ray laser. International groups of experts selected the most promising research projects from among these proposals. The first 14 teams of researchers began work at the European XFEL in September 2017. The biochemist Prof. Lars Redecke and his team from Lübeck University were among the first users. They aim to use the x-ray laser to carry out research into Alzheimer's protein with a view to developing substances that block faulty proteins.
“The European XFEL will enable scientists to venture into unknown worlds and help find answers to questions facing humanity that will improve life on our planet.”
It took eight years to construct the giant research facility at a cost of more than 1.2 billion euros. Germany, home to the European XFEL, meets 58 per cent of the costs. The European XFEL is primarily a European project, however: Britain, Denmark, France, Hungary, Italy, Poland, Russia, Slovakia, Spain, Sweden and Switzerland are involved in the European XFEL alongside Germany. The staff are also international: More than 300 people from 46 countries work here.
The European XFEL was built and is operated by the European XFEL GmbH, a non-profit limited company. The main shareholder is the Hamburg-based research centre DESY and it has an annual budget of 117 million euros.
Can we achieve it together? How big does research need to be?
The European XFEL was only possible because 11 European countries were involved in developing and building it. What do you think? Do we need large-scale projects such as these, and do we need international cooperation to address the challenges of the future? Discuss this with us and other alumni in the Community Group “Studium, Forschung und Bildung” (Study, Research & Education)!