Germany’s largest scientific organisation. scientific largest Germany’s DESY is a member of the Helmholtz Association, universe. the onto windows new completely up open and energies to record particles X intense most the generate DESY facilities The tools. research unique are Zeuthen and Hamburg in locations its at builds and DESY develops that detectors and accelerators The biomolecules. between place take that processes vital the and nanomaterials of innovative behaviour to the particles elementary of tiny interaction the from –ranging variety its all in microcosm the DESY at to explore facilities large‑scale the use Researchers centres. accelerator particle world’s leading of the one DESY is centre research DESY The

- r ay radiation in the world, accelerate accelerate world, the in ay radiation

femto – The DESY research magazine | Issue 01/16 X-ray laser X-ray super The ZOOM The DESYresearch magazine–Issue01/16 Why van Gogh’s van Why Sunflowers are wilting are Sunflowers assemble themselves assemble Nanostructures Nanostructures Breakthrough in Breakthrough crystallography crystallography

femto 01/16 femto 01/16 Imprint

femto is published by Translation Deutsches Elektronen-Synchrotron DESY, TransForm GmbH, Cologne a research centre of the Helmholtz Association Ilka Flegel

Editorial board address Cover picture Notkestraße 85, 22607 Hamburg, Germany Dirk Nölle, DESY Tel.: +49 40 8998-3613, fax: +49 40 8998-4307 e-mail: [email protected] Printing and image processing Internet: www.desy.de/femto Heigener Europrint GmbH ISSN 2199-5192 Copy deadline Editorial board March 2016 Till Mundzeck (responsible under press law) Ute Wilhelmsen

Contributors to this issue Frank Grotelüschen, Kristin Hüttmann

Design and production Diana von Ilsemann

The planet simulator A new high-pressure press at DESY’s X-ray source PETRA III can simulate the interior of planets and synthesise new materials. The Large Volume Press (LVP), which was installed in collaboration with the University of Bayreuth in Subscribe to Germany, can exert a pressure of 500 tonnes on each of its three axes. That corresponds to 300 000 times the atmospheric pressure or the pressure that reigns 900 kilometres under the Earth’s surface. The colossal device is femto free of charge! 4.5 metres high and weighs 35 tonnes. Depending on the desired pressure, samples with a size of up to one cubic centimetre can be compressed. That’s www.desy.de/femto or +49 40 8998-3613 roughly the size of a normal die for board games, and in the field of high- pressure experiments it’s very impressive. The LVP is the world’s biggest press installed at a synchrotron.

The DESY research magazine

Cover picture In the new European XFEL X-ray laser, electrons are accelerated to almost the speed of light and then made to generate intense ultrashort X-ray flashes. The accelerator elements are housed in yellow pipes that are 12 metres long and almost one metre thick. In a test hall at DESY, the complex components are carefully checked before they are installed in the X-ray laser facility’s accelerator tunnel. femtoscope Picture: DESY, Dirk Nölle DESY, Picture: femto 01/16 Contents

ZOOM

The European XFEL is a high-speed camera, a supermicroscope A superlative and a planet simulator rolled into one. Starting in 2017, its intense ultrashort X-ray laser flashes will give researchers from scientific institutes and industry completely new insights into the nanoworld. They’ll be able to study the details of viruses at the atomic level, the X-ray laser molecular composition of innovative materials, films of chemical reactions and the characteristics of matter under extreme conditions. DESY is the main shareholder in this engine of discovery. Pages 12–31

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CAMPUS ZOOM SPECTRUM

06 Perfection isn’t everything 14 Light for the future 30 Research summary A breakthrough in crystallography The European XFEL - Footballs with no resistance 10 Nanostructures assemble 17 “Light at the end of the tunnel” - Exploding nanoparticles themselves Massimo Altarelli on the world’s - Scientists X-ray protein crystals A new technique for building biggest X-ray laser facility inside cells metallic nanosystems - A new nanomaterial 18 Experiments at the European XFEL - Molecular breakdance 34 Licensed to measure New research opportunities for - Optical funnel for nanoparticles A new electronic standard many natural sciences - One gene, two proteins, one conquers the market complex 20 Precision from the production line 36 An unknown source of oxygen Challenges of accelerator in the Earth’s mantle construction New iron oxides provide decisive clues 25 “A triumph for DESY” Three questions 38 Particle accelerator on for Helmut Dosch a microchip Moore Foundation 26 European partners promotes innovative technology Eleven countries are helping to build the European XFEL 39 Why van Gogh’s Sunflowers are wilting 28 A bike ride through the X-ray investigation shows how X-ray laser chrome yellow darkens Two schoolboys explore the European XFEL

SECTIONS

02 femtoscope 33 femtomenal The planet simulator 16 288 metres of tunnels

09 femtopolis 40 femtocartoon Duck tales Would light sabres win arguments?

5 femto 01/16 CAMPUS Perfection isn’t everything

A pinch of disorder has generated a breakthrough in crystallography

Slightly “disordered” crystals (right) of complex biomolecules such as that of the photosystem II molecule shown here produce a continuous diffraction pattern under X-ray light that yields far more information than the so-called Bragg peaks of a more strongly ordered crystal (left). Picture: DESY, Eberhard Reimann Eberhard DESY, Picture:

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n science as in real life, being perfect is not always the best option. Sometimes it’s the small irregularities that are really I interesting. In human terms, this is not a great new insight. Minor character quirks and individual deviations from the norm of a perfect body are generally not regarded as disturbing. Instead, these are the attributes that make an individual lovable and interesting. By contrast, for a precise science such as crystallography, which depends on physical measurement methods and Henry Chapman is the head of the Coherent X-ray Imaging division at the Center for Free-Electron Laser mathematical analyses, this idea has introduced Science at DESY. a genuine paradigm shift. When a crystal is illuminated with X-ray light, a characteristic pattern of bright dots – known as Bragg peaks – appears on the detector. Such diffraction patterns are used to reconstruct the detail,” says Chapman, who is also a professor spatial structure of a crystal, right down to the at the University of Hamburg and a member precise atomic structure of the molecules of of the Hamburg Centre for Ultrafast Imaging which the crystal consists. The basic assumption (CUI). The new method works for less ordered used to be that the more perfectly the molecules crystals and circumvents the usual need for prior were ordered in the interior of the crystal, the knowledge and chemical insight. “This discovery better the reconstructed likeness of the molecule has the potential to become a true revolution would be. However, for biomolecules, which for the crystallography of complex matter,” says are especially complex and very difficult to the Chairman of DESY’s Board of Directors, crystallise, perfection isn’t everything. It’s the Helmut Dosch. This scientific breakthrough gives tiny imperfections of somewhat “disordered” researchers access to the blueprints of thousands crystals, in which individual molecules are of molecules of great relevance to medicine and slightly out of kilter, that can provide crucial biology. The spatial structure of biomolecules information for determining the crystal’s reveals their modes of action and can provide the structure. This information is hidden in the faint basis for the development of tailor-made drugs. continuous diffraction pattern that used to be regarded as a distracting background not worthy “Extreme Sudoku in three dimensions” of attention. But even with a perfect crystal, the Bragg peaks alone are not enough to determine a completely unknown protein structure. “This task is like “This discovery has the extreme Sudoku in three dimensions and a million boxes, but with only half the necessary potential to become clues,” explains Chapman. In crystallography, this complicated puzzle is referred to as the a true revolution for phase problem. Without knowing the phase of the diffracted light waves – the lag of the crests the crystallography of one wave to another – it is not possible to of complex matter” compute the structure of the molecule from the Helmut Dosch, DESY measured diffraction pattern. But the phases of the individual waves can’t be measured. To solve the tricky phase puzzle, more information This discovery was made by a team headed by must therefore be known than just the measured DESY scientist Henry Chapman from the Center Bragg peaks. This additional information for Free-Electron Laser Science (CFEL) in Hamburg. can sometimes be obtained from the known The researchers developed a new method of structure of a closely related molecule or through determining the spatial structures of proteins comparison with the diffraction patterns of and other biomolecules that in many cases crystals of chemically modified molecules. This had not been accessible by means of previous barrier to the determination of the structure is techniques. “Our discovery will allow us to most severe for large protein complexes such as directly view large protein complexes in atomic membrane proteins.

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The analysis of the Bragg peaks alone (left) reveals far less detail of the molecule under study than the additional analysis of the continuous diffraction pattern (right). The magnifying glasses show real data from the study.

no longer the best to analyse with the novel method. Instead, the best crystals are imperfect crystals. “For the first time, we have access to Chapman realised that imperfect crystals and single-molecule diffraction – we have never the phase problem are linked. The key lies in the had this in crystallography before,” Chapman weak, continuous diffraction pattern generated explains. “But we have long known how to solve by “disordered” crystals. This continuous single-molecule diffraction if we could measure background is generally thought of as a nuisance it.” The field of X-ray coherent diffractive imaging, and not used for the structural analysis, although spurred by the availability of laser-like beams it can be useful for providing insights into the from X-ray free-electron lasers, has developed vibrations and other dynamics of molecules. powerful algorithms to directly solve the phase But when the disorder consists only of slight problem in this case, without having to know displacements of the individual molecules anything at all about the molecule. “You don’t from their ideal positions in the crystal, then even have to know chemistry,” says Chapman, the background encodes the full continuous “but you can learn it by looking at the three- diffraction pattern from the individual “single” dimensional image you get.” molecules in the crystal. “If you would shoot X-rays on a single molecule, it would produce a continuous “For the first time, diffraction pattern free of any Bragg spots,” explains lead author Kartik Ayyer from we have access to Chapman’s CFEL group. “The pattern would be single-molecule extremely weak, however, and very difficult to measure. But the ‘background’ in our crystal diffraction – we have analysis is like accumulating many shots from individually aligned single molecules. We never had this in essentially just use the crystal as a way to get a lot of single molecules, aligned in common crystallography before” Henry Chapman, DESY orientations, into the beam.” The continuous diffraction pattern provides enough additional information to solve the phase problem directly, To experimentally demonstrate their novel without having to resort to other measurements analysis method, the Chapman group teamed or assumptions. In the analogy with the Sudoku up with the group of Petra Fromme and other puzzle, the measurements provide enough clues colleagues from Arizona State University, the to always arrive at the right answer. University of Wisconsin, the Greek Foundation for Research and Technology – Hellas FORTH The best crystals are imperfect crystals and the SLAC National Accelerator Laboratory in This novel concept leads to a paradigm shift in the USA. They used the world’s most powerful crystallography – the most ordered crystals are X-ray laser, LCLS at SLAC, to X-ray imperfect

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femtopolis

over the world. They became sad useful for determining the unknown Duck examples of global material cycles. structure of a biomolecule from the A more positive showcase corresponding diffraction patterns. for rubber ducks is in the field of The “Fourier duck” first tales crystallography, where they help appeared in a book about optical scientists analyse the spatial transforms published by the British

structure of complex biomolecules crystallographers Charles Alfred From the bathtub to with the help of intense X-ray Taylor and Henry Solomon Lipson the research frontier light. This analysis is carried out in 1964. Today, it is widely used in by means of complex calculations educational materials and is familiar rubber duckie that bobs known as Fourier transforms – and to almost every student who takes an around on the surface that’s where the ducks come in. introductory course in crystallography. of the bathwater is most They replace the biomolecules in For decades, it was believed A people’s favourite bathtub mathematical models, thus serving that the more precisely the ducks toy. Scientists have also discovered as test objects whose shape is are arranged on their lattice points, just how useful it can be. In January known and neither too complicated the better. But nature is not always 1992, a container load of plastic nor too simple. Lots of ducks sitting precise. Surprisingly, a lot more toys was swept overboard from a in a lattice represent a crystal that can be learned about the ducks Hong Kong-based cargo ship in the the researchers have painstakingly – or rather, the molecules they eastern Pacific. The toys became grown from biomolecules in represent – if they are not sitting part of an unplanned large-scale order to irradiate it with X-rays in overly perfect rows. This insight effort to monitor the spread of and determine the biomolecules’ has resulted in a paradigm shift plastic rubbish in the oceans. structure from the resulting for crystallographers – and more Almost 29 000 rubber ducks and diffraction pattern. Only if the freedom for the ducks, which are other plastic toys were carried by mathematical models can reconstruct now allowed to swim around their ocean currents to destinations all the duck are the models deemed lattice points once in a while.

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microcrystals of a membrane protein complex Nano­ called photosystem II, which is part of the photosynthesis machinery in plants. Including the continuous diffraction pattern in the analysis immediately improved the spatial structures resolution – compared to the analysis of the Bragg peaks alone – by around a quarter, from 4.5 ångströms to 3.5 ångströms (an ångström is 0.1 nanometres or billionths of a metre assemble and corresponds roughly to the diameter of a hydrogen atom). The image obtained showed details of molecular features that usually require fitting a chemical model to see. “That is a pretty themselves big deal for biomolecules,” explains co-author Anton Barty from DESY. “And we can further New technique for manufacturing improve the resolution if we take more patterns.” metallic nanosystems The team only needed a few hours of measuring time for these experiments, while full-scale measuring campaigns usually last a couple esearchers at DESY have developed a of days. new procedure that enables metallic The scientists hope to obtain even more nanostructures to assemble and line detailed images of photosystem II and many R up all by themselves. This so-called other macromolecules with their new technique. bottom-up approach offers a quick and simple “This kind of continuous diffraction has actually alternative to existing procedures, making it been seen for a long time from many different interesting for commercial applications as well, poorly diffracting crystals,” says Chapman. “It in which nanostructures are used more and more wasn’t understood that you can get structural often. “Most importantly, the method allows information from it and so analysis techniques extremely uniform nanostructures to be created suppressed it. We’re going to be busy seeing if in highly regular patterns with comparatively we can solve structures of molecules from old little effort,” explains Denise Erb, the lead author discarded data.” of the publication. A special setup, developed by DESY scientist Kai Schlage, enabled the scientists Nature, 2016; DOI: 10.1038/nature16949 to actually watch the nanostructures as they grew, at DESY’s X-ray source PETRA III. Nanostructures are tiny objects smaller than a thousandth of a millimetre. A nanometre is one millionth of a millimetre. Compared to this, a human hair is huge, having a thickness of almost 40 000 nanometres. For many scientific studies and technological applications, it is essential that the nanostructures repeat in a specific pattern. The size and separation of the individual elements of such patterns can lie anywhere between a few nanometres and several hundred nanometres. Nanostructures are turning up more and more often in everyday life. “Nanostructures permit improved or new functionalities. In catalytic converters, for example, data storage devices or sensors,” says Erb. “The dimensions of the products we normally deal with in our everyday lives are generally of the order of a few centimetres or more. So it would be nice to be able to manufacture materials that incorporate

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nanostructures on that scale too. And ideally they should be quick and cheap to make as well.” However, it is often very challenging to create

nanostructures both on large surfaces and with Denise Erb, DESY Picture: the necessary regularity. This is where the new method comes into its own. The conventional top-down technique can be compared with sculpting: One begins by coating a surface with the corresponding material. The desired pattern is then gradually carved out of this layer by removing specific areas. This is done bit by bit, which means that the manufacturing time depends directly on the size of the required area. The advantage is that virtually any pattern can be created. Building up a nanostructure using the bottom-up approach: On the “Nanostructures approximately ten nanometre (nm) deep grooves of an permit improved or aluminium oxide crystal (grey), a 40 nm thick layer new functionalities. In of copolymers (brown) is deposited. Metal nanodots catalytic converters, for (green) then grow on this layer, reaching a height example, data storage of this kind create particularly uniform patterns. of about 10 nm. The area Erb and her colleagues have used this procedure shown measures 3000 nm devices or sensors” to combine crystals, polymers and metals. by 1800 nm. Denise Erb, DESY “A particularly exciting aspect, from a scientific point of view, is the possibility of The method used by the researchers at DESY, watching the nanostructures form in real time on the other hand, is based on the so-called using X-ray diffraction, and observing how they bottom-up approach. This makes use of the fact develop their physical properties,” says Ralf that certain materials have a natural tendency Röhlsberger, who is in charge of the research to form nanostructures. “In bottom-up methods, group at DESY. At DESY’s X-ray light source which are also known as self-organising PETRA III, the scientists watched the process live. methods, we do not force the material to adopt Using a special setup, they let the metal nano­ a certain pattern, as in the top-down method,” structures grow under various conditions directly explains Erb. “Instead, we create conditions in the X-ray beam. that allow the material to self-assemble and With the help of the X-rays, the scientists form nanostructures. The shape of these can see, for example, how the shape and the nanostructures cannot be chosen arbitrarily, magnetic properties of the nanostructures evolve. as in top-down procedures – they are dictated They can thus not only examine the results of by the properties of the material. Nonetheless, their efforts but also study the intermediate the nanostructures that form are extremely stages in detail. As in football, the scientists interesting to us, and useful.” The big advantage are not simply interested in the final outcome is that the nanostructures form over the entire of the game, but also in how it came about. surface at the same time, so that the speed with They would like to know, for example, which which the pattern is formed no longer depends parameters played a key role. “Through our on the size of the surface. research, we hope to establish a method by which To obtain the desired nanostructures using nanostructures can be created more easily and the bottom-up approach, it is also possible quickly,” concludes Erb, “but also to develop a to combine several different self-organising better understanding of why these tiny structures materials. The assembly of the nanostructures behave magnetically, chemically and optically then takes place in a series of steps, so that the the way they do.” arrangement of the first structure affects the formation of the second structure. Combinations Science Advances, 2015; DOI: 10.1126/sciadv.1500751

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ZOOM A superlative X-ray laser

The European XFEL is a high-speed camera, a supermicroscope and a planet simulator rolled into one. Starting in 2017, its intense ultrashort X-ray laser flashes will give researchers from scientific institutes and industry completely new insights into the nanoworld. They’ll be able to study the details of viruses at the atomic level, the molecular composition of innovative materials, films of chemical reactions and the characteristics of matter under extreme conditions.

Eleven countries are participating in this joint European project. DESY is the main shareholder and is responsible for the construction and operation of the particle accelerator with its innovative superconducting technology. The European XFEL is mostly located in underground tunnels. The 3.4-kilometre-long facility extends from DESY in Hamburg to the neighbouring town of Schenefeld in the German federal state of Schleswig-Holstein.

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Pictures: European XFEL / DESY femto 01/16 ZOOM Light for the future

The European XFEL in Hamburg will produce the most intense X-ray laser flashes in the world

he European XFEL stretches for 3.4 kilometres from Hamburg-Bahrenfeld to the town of Schenefeld in Schleswig- T Holstein. It’s the world’s most powerful X-ray laser and one of Europe’s biggest scientific facilities. At its heart is a particle accelerator that is close to two kilometres long. It accelerates electrons to almost the speed of light. Special magnet structures called undulators force the speeding electrons to fly along a slalom path.

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As a result, the particles emit short and very powerful X-ray flashes that also have the properties of laser light. The X-ray flashes make it possible for researchers to image ultrafast processes, because each individual flash is less than 100 quadrillionths of a second long and bright enough to create snapshots. This makes it possible to “film” molecular reactions and thus understand processes that are fundamental to chemical production methods in industry or to At the electron source [1], a powerful laser the mechanisms of medical effects. In addition, knocks several billion electrons at a time the short-wavelength laser flashes can make out of a caesium telluride electrode. These the composition of nanomaterials and complex electrons are bundled into tiny bunches, which are given a boost in the accelerator biomolecules visible at the atomic level. On the modules [2]. Powerful radio waves are basis of this knowledge, researchers can go on fed into these modules, and the electrons to develop innovative customised materials and “ride” the waves like surfers on the ocean. drugs. The X-ray laser also makes it possible to To ensure that the speeding electrons are

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generate and analyse extreme states of matter – A look at the interior of such a module reveals for example, the high pressures and temperatures a complex structure. The electrons fly through that exist in the interior of planets. Under a thin pipe from which all the air has been such extreme conditions, matter behaves very evacuated. Most of the module’s components are differently than under “normal” conditions. used for thermal insulation and cooling – various “The European XFEL will open up entirely pipes through which liquid helium is pumped in new opportunities for scientists from research order to reduce the temperature inside the pipe institutes and industry,” says Massimo Altarelli, to minus 271 degrees Celsius. Chairman of the European XFEL Management These extreme measures are necessary to Board. “Much of this work will be fundamental ensure that the core components – the cavity research. This kind of research develops its resonators – can function properly. These shining biggest effects usually not in the short term and silvery components are responsible for the sometimes not in the area that was originally actual acceleration of the electrons. With the targeted. But without fundamental research, the help of powerful radio waves, they accelerate life we live today would not be conceivable.” the tiny electron bunches to almost the speed of light. Every module is equipped with eight A race track for electrons cavities made of the superconducting metal Eleven countries are participating in this joint niobium. “Superconducting” means that the European project. DESY is the main shareholder metal completely loses its electrical resistance and is responsible for the construction and and thus conducts electricity without any loss of operation of the particle accelerator with its energy – when cooled to ultracold temperatures, innovative superconducting technology, which that is. The advantage of this technology is that has already been tested at DESY’s pioneering it enables considerably more electron bunches to X-ray laser facility FLASH. The accelerator be accelerated and thus more X-ray flashes to be modules are massive yellow pipes that are generated per second than conventional, normal- 12 metres long and almost one metre thick. conducting accelerator technology.

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not slowed down by air, they fly through X-ray flashes, which are used by researchers vacuum pipes [3]. Once the electrons have at the measuring stations [5] to illuminate a reached their maximum energy, they pass variety of samples. The basic principle here is through special magnet structures called that the atoms of the sample material deflect undulators [4]. The undulators force the the X-ray light, and detectors then intercept electrons to run a slalom course, causing the deflected radiation. Subsequently, them to emit X-ray flashes. At the end of computers [6] are used to precisely calculate the undulator section, this radiation has the spatial structure of the sample, for amplified into extremely intense ultrashort example, at the atomic level.

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X-ray free-electron lasers are being built all over the world. About half of these facilities are already in operation. European XFEL Schenefeld & Hamburg (DE)

FLASH | FLASH II PAL-XFEL DESY, Hamburg (DE) PAL, Pohang (KR) LCLS | LCLS II SLAC, Menlo Park (US) SACLA SCSS SwissFEL RIKEN, Harima (JP) PSI, Villigen (CH)

FERMI Elettra Sincrotrone Trieste, SXFEL Trieste (IT) SINAP, Shanghai (CN) Short-wavelength X-ray radiation

Long-wavelength X-ray radiation

A total of 101 superconducting modules will put the the electron bunches, the other for the X-ray electrons through their paces in the two-kilometre- laser flashes generated in the undulators. To long accelerator tunnel. At certain points, the separate the two beams, bending magnets particles pass through “warm” – that is, uncooled gently direct the electron beam to the right, into – sections of beam pipe on which various devices another tunnel. Meanwhile, the X-ray flashes are mounted, including magnets that bundle the race straight ahead until they hit a special mirror electron bunches. At the end of the accelerator, mounted at an obtuse angle. This mirror has been the tunnel branches into two tubes. Each of them ground to nanometre precision and functions as contains another key component of the facility: a distribution station. It either allows the X-ray the undulators. These are permanent magnets flashes to go straight on past it into one pipe or mounted above and below the electron beam pipe, deflects them by a tenth of a degree into another with their north and south poles alternating at four- pipe. The two pipes run alongside one another centimetre intervals. These force the electrons to for 600 metres, with the distance between them follow a slalom course. gradually increasing. At the end of the tunnel, after 3.4 kilometres, they are 1.40 metres apart On a slalom course when they penetrate a thick wall of concrete. The electrons, which are flying at almost the Directly behind this wall is the big experiment speed of light, emit intense X-ray radiation hall with its measuring huts, whose walls contain in each curve. The special feature of the free- lead as shielding against the X-ray radiation. The electron laser is that it has not just one undulator first experiments will be conducted in these huts but 35 of them, arranged one after the other in 2017. The X-ray flashes will illuminate samples over almost 200 metres. “When the X-ray light of various kinds, enabling the scientists to study emitted by one undulator oscillates in sync with their interior structures and processes. the light of the next one, the light is amplified,” “We’ve worked for many years to build this explains Tobias Haas, technical coordinator at the facility,” says Haas. “Now we feel as though we European XFEL. “That’s the only way I can get the can finally see the marathon’s finish line.” The amplification effect I need for a laser.” In order European XFEL will initially have six measuring to be able to optimally adjust the laser effect, stations, but two additional tunnels have already the five-metre-long undulators are separated by been dug and can be equipped with additional intermediate sections called phase shifters. undulators if necessary. In the final configuration, Past the undulator section, the evacuated the researchers in the experiment hall will be beam pipe branches into two. One branch is for able to use up to 15 measuring stations.

16 femto 01/16 Picture: European XFEL European Picture: Massimo Altarelli, Chair­ “Light at the end man of the European XFEL Management Board, is looking forward to the first of the tunnel” experiments at the world’s biggest X-ray laser facility

femto: After the six-year construc­ femto: How will society benefit from about the project. But it was more tion period, when will research at this research? difficult to get the approval of the European XFEL begin? political decision-makers and Altarelli: The European XFEL will financial sponsors and to agree on Altarelli: I hope we will see the open up entirely new possibilities a legal structure. The international first X-ray laser flashes in February for scientists from research agreement was finally signed in or March 2017. We are currently institutes and industry. Much of this September 2009, and at that point building the measuring stations in work will be fundamental research. the construction could begin. the experiment hall, and the first This kind of research develops its two of them will start to operate biggest effects usually not in the femto: Did the construction proceed between the spring and summer of short term and sometimes not in as planned? 2017. All three undulator sections the area that was originally targeted. and six measuring stations should But without fundamental research, Altarelli: Of course at times I wished be in operation by the middle of the life we live today would not be it could have gone faster. But after 2018. conceivable. For example, in the all, we were dealing with a new medium and long terms I think technology at the boundaries of femto: What new insights will the there will be great opportunities feasibility, which we had to translate facility provide for researchers? in medical research – for instance, into series production. That was a in the development of drugs and tremendous challenge. All things Altarelli: The European XFEL has therapies – or in the development considered, the delays were kept a number of key advantages of renewable sources of energy and within limits, and we can be very compared to existing X-ray sources. materials for new technologies. And satisfied with the result! Among other things, its flashes we shouldn’t underestimate the are significantly shorter. They’re fact that the young scientists who femto: How are you and your only about ten femtoseconds long. come to us will be able to gather 280 coworkers feeling at the That will make it possible to film experience in a leading global moment? molecular processes and chemical research establishment – experience reactions. We’ll be able to literally that they can later apply in the Altarelli: We’re feeling very good. see the ‘action’, just like in an fields of science and industry to After a long and complicated action film. In addition, the flashes develop new products and processes. planning and construction phase, have laser properties. In the future, we’re now literally seeing the light that will enable us to use even femto: The German government gave at the end of the tunnel – not only samples that cannot be crystallised the European X-ray laser project the for our team but also for researchers in order to analyse them in detail green light back in 2003. Why did it all over Europe. Hundreds of experts at the atomic level. If we succeed take so long to begin construction? are already coming to Hamburg for in deciphering the structure of our annual users’ meeting. That individual protein molecules that Altarelli: The European XFEL would shows the great interest and the are of interest to pharmacologists, have been too big and too expensive spirit of optimism that scientists are that would be fantastic! What all for a single country to build. feeling right now. these methods have in common That’s why it was planned as an is that they enable us to examine international project from the very previously hidden details and start. It was easy to get scientists processes in the nanocosmos. from other countries enthusiastic

17 femto 01/16 Experiments at the

European XFEL XFEL, Rey Hori European Picture:

With its extraordinarily bright, highly energetic and extremely intense X-ray flashes, the European XFEL will yield new insights in a wide range of research fields. It will, for instance, enable scientists to produce images of viruses and biomolecules at atomic resolution, to film chemical reactions in superslow motion and to investigate materials under the extreme conditions that reign deep within giant gas planets. There are many fields of application, ranging from biology, medicine, chemistry and physics to materials science, electronics, nano­ technology and many others. With a total of six measuring stations, the facility Planned setup offers a wide range of opportunities for scientific investigation. Through their of the FXE measuring station membership in user consortia, among others, numerous institutions participate in various aspects of the experimental activities at the European XFEL. DESY too is involved in such consortia, sometimes in a leading capacity.

Investigating the dynamics of the nanoworld Nanosystems are an increasingly common feature of the everyday It enables researchers to investigate the nanostructure and world. Examples include metallic nanoparticles in the catalytic dynamics not only of solid materials such as metals but also of soft converters of cars. An investigation of the properties and the materials such as polymers and gels and even biological samples. dynamics of such systems not only provides a better understanding For the investigation of a broad range of samples, various analytic of their fundamental nature but also enables an enhancement of methods are available, which make use of the laser properties of the everyday products containing nanoparticles. The MID (Materials X-ray free-electron laser radiation, its short pulses and its high Imaging and Dynamics) measuring station is used for such research. intensity.

A 4D supermicroscope in space and time The principal objects of investigation at the SPB/SFX (Single The samples are shot laterally through the X-ray beam. Whenever a Particles, Clusters, and Biomolecules and Serial Femtosecond pulse of the intense radiation hits a crystal of biomolecules, for Crystallography) measuring station are biomolecules, nano­crystals, example, a distinctive X-ray diffraction pattern is generated, which virus particles, cell organelles and atom clusters. As a rule, the aim enables the biomolecule’s structure to be computed. The spatial is to determine the two and three-dimensional structure of the object structure of a biomolecule provides information about its mode of under investigation to an atomic resolution of less than one nano­ action and can yield clues for the development of new drugs. Apart metre (a millionth of a millimetre). However, the 3D microscope is, from structural biology and cell biology, a host of other fields will in fact, a 4D supermicroscope if the high time resolution is taken benefit from the methods of investigation available at this measuring into account. station, including materials science and nanotechnology.

The exoplanet simulator The “normal” conditions on the surface of the Earth are the absolute known as exoplanets. Various methods are used to generate these exception for the universe as a whole. Most matter in the universe extreme conditions, including high-power optical lasers, diamond exists at much higher pressures and temperatures and under more anvil cells and strong pulsed magnets. The investigation of matter powerful electromagnetic fields. TheHED (High Energy Density Sci- under extreme conditions provides a more complete picture of its ence) measuring station can simulate the extreme conditions that material properties beyond the narrow scope of what we call exist for example in giant gas planets in other solar systems, also “normal”.

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An ultrafast quantum film camera Thanks to the ultrashort exposure times, it is possible to observe Dynamic processes in the nanocosmos generally occur over an processes such as the complex interplay of molecules during a unimaginably short timescale of just a few quadrillionths of a second chemical reaction, with the X-ray laser providing previously (femtoseconds). The FXE (Femtosecond X-Ray Experiments) inaccessible information about the detailed steps. The process measuring station uses the extremely short X-ray flashes from the under investigation is first triggered by a laser pulse and then, after European XFEL to produce sharp images of extremely rapid a precisely defined amount of time, imaged by means of an X-ray processes in solids, liquids and gases. Examples include shock flash. The experiment is repeated many times, each time with the waves propagating, nanoparticles exploding and just about any moment of exposure at a slightly later point in time. The result is a chemical reaction. sequence of stills that can be assembled into a film of the process under investigation.

Zooming in on the quantum world many separate charged parts. SQS offers researchers a variety There are many unsolved questions in the realm of atoms and of methods with which to investigate these fragments in detail. molecules. The SQS (Small Quantum Systems) measuring station The determination of precise atomic data is vital for the is used to investigate the behaviour of small quantum systems development not only of new theoretical models but also of many comprising between one and tens of thousands of atoms. In other experimental methods. Scientists require reliable data in order particular, this multiphoton camera focuses on the interaction to support and quantify their results – data that is often lacking even between these smallest structural units and the extremely intense for comparatively simple systems. It is therefore vital to be familiar X-ray laser flashes. Multiphoton processes often produce lots of with the participants of this process – the atoms – in order to electrons and highly charged ions, with molecules breaking up into understand it as a whole.

The structure and dynamics of complex materials Researchers who are working with the SCS (Spectroscopy and ideal for investigating, among other things, nanostructured materials Coherent Scattering) measuring station use what are called “soft” and ultrafast magnetisation processes. The potential fields of X-rays to investigate the electronic and atomic structure as well as application for this type of investigation include materials science, the dynamics of complex and functional materials. Soft X-rays have surface chemistry and catalysis, nanotechnology and the dynamics less energy and a longer wavelength than hard X-rays. They are of condensed matter.

Electron tunnel Electron switch

Photon tunnel Electron bend MID Materials Imaging and Dynamics Undulator Electron dump HED High Energy Density Science

Option for two further undulators and four instruments SPB/SFX Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography

FXE Femtosecond X-Ray Experiments

SQS Small Quantum Systems SCS Spectroscopy and Coherent Scattering Linear accelerator for electrons SASE 2 SASE 1 SASE 3

(10.5, 14, 17.5 GeV) 0.05 nm – 0.4 nm 0.05 nm – 0.4 nm 0.4 nm – 4.7 nm XFEL Graphic: European

19 femto 01/16 ZOOM Precision from the production line

The production of the superconducting accelerator modules was one of the major challenges in the project to build the European XFEL

here are several accelerator-driven X-ray lasers in operation all over the world. The pioneer was FLASH, which commenced T service in 2000 at DESY. For a number of years, LCLS in California and SACLA in Japan have been providing high-intensity X-ray pulses. As documented in numerous publications in the renowned journals Nature and Science, both

facilities have delivered impressive proof of Reinhard Brinkmann is the value of such light sources to the research Director of the Accelerator community. They will be joined at the end of 2016 Division at DESY. by the SwissFEL at the Paul Scherrer Institute in Switzerland. The European XFEL has one key advantage over these other facilities: Because it uses superconducting technology, it is able to deliver significantly more X-ray flashes per switch it on for much longer than a copper cavity.” second than normal-conducting facilities can. Thanks to this technology, the European XFEL This capability is of major benefit for many will be able to produce 27 000 X-ray flashes per experiments. second – more than 200 times as many as the In conventional accelerators, water-cooled number produced by the other facilities. cavity resonators made of copper are used to This means that experiments that take a accelerate the electrons to high energies. “But the number of hours to complete at other X-ray laser copper heats up due to its electrical resistance,” facilities will require only a few minutes at the explains Reinhard Brinkmann, Director of the European XFEL. It will therefore be possible to Accelerator Division at DESY. “That’s why you conduct more experiments in the same amount can only feed radio waves into the cavities for a of time. Moreover, the higher rate of X-ray flashes tiny fraction of a second; otherwise the material from the European XFEL will provide greater would melt.” This also means that you have temporal resolution, thus enabling even more- to wait a moment for the copper to cool down detailed investigations of chemical reactions. before applying the next pulse of radio waves. However, superconducting accelerators do This limits the rate at which the laser can deliver have one disadvantage: The technology is more X-ray pulses. Current free-electron lasers can expensive and much more complicated than that produce a maximum of 120 flashes per second. of conventional accelerators. For example, key components have to be cooled with liquid helium More flashes thanks to superconductivity to around minus 271 degrees Celsius. “To a large To circumvent this limitation, DESY opted for extent, we were able to use the liquid-helium another approach, namely superconductivity. plant from the former large-scale accelerator A superconductor possesses zero electrical HERA,” says DESY scientist Hans Weise, resistance. As Brinkmann explains, this means coordinator of the European XFEL Accelerator that the radio waves don’t heat up the cavity Consortium. “That meant we didn’t have to to any appreciable extent. “As a result, you can build everything from scratch.”

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The biggest challenge was to develop and method. “We scanned all 16 000 niobium sheets,” manufacture the superconducting cavities, which Brinkmann explains. “Only a few percent had to are made of niobium rather than copper. DESY be rejected.” produced the initial prototypes in collaboration with a large number of partners based both within Germany and abroad. This was a major “We scanned all 16 000 breakthrough, but one problem remained: Over 800 superconducting cavities were needed for the niobium sheets; only three-kilometre-long European XFEL. Some form of series production was therefore required. a few percent had to be rejected.” High purity for high performance Reinhard Brinkmann, DESY The researchers therefore devised a complex quasi-industrial process that involves numerous partners both in Germany and abroad. Even Each sheet that passed scrutiny was then cut and producing the raw material is an elaborate pressed into shape, before being welded into the process. The niobium must be extremely pure, shape of a cavity – a shiny silver tube, one metre which means it has to be re-melted up to eight in length and segmented like a caterpillar. “The times in special furnaces. Each melting process manufacturing process has to be kept extremely successively reduces the level of impurities, clean,” says Brinkmann. “Even a speck of dust and the final result is ingots of extremely pure can be enough to stop a cavity working as it niobium, which are then rolled into sheets. In should.” For this reason, some of the process order to check for any remaining impurities, stages were conducted in cleanrooms, where the DESY scientists inspected each individual air is scrupulously filtered and particle counters sheet using a special eddy-current testing monitor air quality. To prevent components being contaminated, workers wore what looked like surgical gowns, including face masks, hair nets and gloves. An electron beam was used to weld the niobium sheets. After the welding, the cavities underwent an elaborate cleaning process. They were first dipped into an electrochemical acid bath, then given a high-pressure rinse with specially purified water and finally baked for

The niobium (above) is re-melted a number of times (above left) and the rolled sheets (left) are precisely scanned.

Superconducting cavities in the cleanroom

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several hours at 120 degrees Celsius. “There are processes here which we don’t yet fully understand in all their detail,” Brinkmann explains. “You could almost say that there’s a Assembly of an accelerator bit of alchemy to it all.” module (right); connecting Many of the methods that were used were radio frequency couplers first tested at DESY, then exported to industry to cavities in the cleanroom and ultimately enhanced in partnership. “It took (below). a while before we could achieve reliable series production; a lot of it was a laborious process of learning and practicing,” says Brinkmann. “But by the end, the whole industrial production process – from the niobium sheets to the finished cavities – ran very smoothly.” The cavities were supplied by an Italian and a German company, with the last one leaving the production line at the beginning of 2016. There were very few rejects. In fact, barely more than a dozen of the more than 800 niobium tubes required subsequent chemical treatment, and the average accelerating gradient proved to be well above the original specification.

“The industrial delivered their components as punctually as possible. “The late arrival of even a single manufacturing process – component would have had a knock-on effect on the whole process, with the danger of a logjam.” from the niobium sheets A key factor in the success of this enterprise was the close cooperation between DESY, as to the finished cavities – the leader of the Accelerator Consortium, and ran very smoothly” European XFEL GmbH, the company responsible Reinhard Brinkmann, DESY for managing the project as a whole.

Bunches of billions of electrons Following production, the cavities were shipped One key component of the facility is the to Saclay near Paris, where they were assembled, injector. This 50-metre-long part of the facility is in batches of eight, into yellow modules, each responsible for generating the electron bunches, with an integrated helium cooling system, just which are then accelerated over a distance of like a large thermos flask. These 101 modules 1.8 kilometres. The injector functions in the were successively sent back to Hamburg, where following way: At a rate of 27 000 times per they underwent a final series of rigorous tests. second, a laser fires powerful pulses at a pill- Only then could they be installed in the tunnel shaped piece of metal. Each pulse blasts off for the European XFEL. a throng of around ten billion electrons. Two The construction of the accelerator posed not superconducting modules pre-accelerate this only technical but also organisational challenges. throng of electrons and shape it into customised After all, eight countries were involved in bunches. Initially, these bunches are about the process. “Some partners are essentially three millimetres long and one millimetre providing financing, while others are contributing across. During the acceleration, sophisticated components,” explains Riko Wichmann, head technology ensures that these bunches are of the XFEL Project Office at DESY. “In particular, further compressed, until finally they are around coordinating the in-kind contributions was not one thousandth of their original volume. “In easy and created much more work than we had order to generate extremely intense X-ray flashes, originally imagined.” A great many institutes the electrons have to be concentrated into a and companies were involved in building the minuscule area,” explains Weise. accelerator modules. The DESY XFEL project Another extremely sophisticated technique in team had to make sure that all the partners use at the European XFEL is the one that ensures

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Hans Weise is a leading scientist at DESY and coordinator of the European XFEL Accelerator Consortium.

precise synchronisation between the ultrashort electron bunches and the X-ray flashes. This synchronisation is required to be able to film chemical reactions, for example. Here, a pulse of light from a conventional laser triggers the reaction. Then, only a brief moment later, an image of the reaction is captured by means of an X-ray flash from the European XFEL. For this process to function, the optical laser and the European XFEL must be precisely coordinated with one another. This is accomplished by a special synchronisation system based on Testing an a “laser clock” that ticks in an optical fibre accelerator module running along the accelerator tunnel. This system measures the exact intervals between

“In order to generate X-ray free-electron laser is based on the same extremely intense superconducting modules used at the European XFEL, but it produces flashes in the soft X-ray X-ray flashes, the and UV ranges. “If you like, FLASH is a 1:10 scale electrons have to be model of the European XFEL,” says Reinhard Brinkmann. “Over the years, FLASH has given us concentrated into a countless valuable insights into how to design and build the larger facility.” FLASH has been minuscule area” used by scientists from over the world for a Hans Weise, DESY decade now. In fact, such is the interest from the research community that DESY is currently the electron bunches and the X-ray flashes – key doubling the facility’s experimentation capacity. information for the scientists conducting the Other research establishments are now also experiments. planning to use superconducting accelerator This method was already tested at FLASH, technology in the future. These include SLAC in also at DESY. Some 300 metres in length, this California, which has been successfully

23 femto 01/16 ZOOM operating the Linac Coherent Light Source (LCLS), “Having access to an X-ray laser based on a normal-conducting accelerator, since 2009. SLAC is now planning to DESY’s knowledge and set up a second light source in the same tunnel. LCLS-II will be 700 metres in length and equipped experience is the reason with 280 superconducting cavities of essentially the same design as those of the European XFEL. why we’ve made such The ambitious goal is to build a laser at rapid progress” SLAC that, from 2019 onwards, will be capable of John Galayda, SLAC producing one million flashes per second, albeit at longer wavelengths and therefore not with the same high resolution as the archetype in two companies that supplied the European XFEL,” Hamburg. “DESY has given us a lot of support Galayda explains. “For us, it’s a great advantage for our planning,” says project leader John that there are already manufacturers with such Galayda. “Having access to DESY’s knowledge and extensive experience in building these cavities.” experience is the reason why we’ve made such rapid progress.” This was particularly true when it came to designing the highly complex accelerator modules and the superconducting niobium cavities. “We’re buying them from the same

The accelerator modules were transported and installed within the tunnel using the special electric vehicle “Mullewupp” (bottom left).

24 femto 01/16

“A triumph for DESY”

DESY is the main share­ femto: What does the European XFEL This development is attracting the holder of the European mean for DESY? best scientists to Hamburg, and it’s XFEL. Helmut Dosch, the also offering high-tech companies Chairman of the DESY Dosch: The European XFEL is one of a highly attractive environment Board of Directors, talks the world’s most revolutionary large- where they can develop new ideas about the research centre’s scale research projects. It brings and technologies whose impact expectations concerning together a completely novel particle goes far beyond the research the European X-ray laser. accelerator technology, which environment. In these ways, DESY was developed by DESY, with the and its cooperation partners are tremendous potential for discovery making a sustained contribution to that the unique experimentation a new culture of innovation in the opportunities will offer to scientists Hamburg metropolitan region. coming from all over the world. DESY designed this major facility femto: What are the outstanding and established the theoretical features of the European XFEL in and technical foundations for addition to the scientific aspects? its realisation. Last but not least, DESY built FLASH, the pioneering Dosch: The European X-ray laser facility for X-ray lasers of this kind. is already a beacon of highly I am therefore convinced that the professional project management. European XFEL will become a great According to our present state of triumph for DESY. knowledge, the European XFEL will fulfil all of its projected design femto: What perspectives does this parameters, including the project open up for Hamburg as a centre of costs. This once again demonstrates science? DESY’s expertise regarding the design and construction of highly Dosch: With the European X-ray complex particle accelerator laser facility – in synergy with the facilities. The technologies that will outstanding X-ray light sources be used at the European XFEL have PETRA III and FLASH that already already pushed back the boundaries exist at DESY – a worldwide of technical feasibility. That applies unique research infrastructure especially to the two-kilometre- is being created in the Hamburg long superconducting accelerator metropolitan region. Pioneering – a DESY technology. To make the interdisciplinary research European XFEL a beacon of science partnerships have already developed as well, we will have to make some around these facilities in recent pioneering scientific discoveries in years – for example the Center the years ahead. But I have no doubt for Free-Electron Laser Science whatsoever in this respect – our top (CFEL) and the Centre for Structural scientists are already raring to go. Systems Biology (CSSB), which is currently under construction.

25 femto 01/16 European partners NIIEFA UU Eleven countries are helping to build the European XFEL GU KTH MSL

DTU Physto

DESY

NCBJ WUT

CNRS IFJ-PAN CEA

PSI

INFN

CIEMAT CELLS UPM

Institutions and selected - Construction of the 103 accelerator INFN Istituto Nazionale di Fisica Nucleare, in-kind contributions modules (including two prototypes) Milan (Italy)

- Production, testing and delivery of The complete detailed list is available at: DESY Deutsches Elektronen-Synchrotron, superconducting cavities http://www.xfel.eu/project/ Hamburg (Germany) - Cryostats in_kind_contributions/ - Design, manufacturing support and - 3.9 GHz accelerator module for the testing of the superconducting cavities injector DTU Technical University of Denmark, - Design, manufacturing support and Copenhagen (Denmark) testing of the accelerator modules NCBJ National Centre for Nuclear Research, - High-tech components for scientific - Cryogenics for the accelerator complex Świerk (Poland) instruments - Radio frequency provision - Production, testing and delivery of - Construction and operation of the injector HOM couplers and absorbers for the CNRS Centre National de la Recherche - Construction and operation of the main accelerator Scientifique, Orsay (France) accelerator - Programmable logic controllers for - Construction and operation of the - Production of radio frequency couplers scientific instruments beamlines for the superconducting linear accelerator - Safety monitoring WUT Wrocław University of Technology, - Contributions to the facility and CEA Commissariat à l’Energie Atomique et Wrocław (Poland) IT infrastructure aux Energies Alternatives, Saclay (France) - Coordination of the entire facility - Production, testing and installation of - Assembly of modules consisting of eight - Awarding and monitoring of contracts vertical test stands for the cavity test superconducting cavities each - Commissioning of the European XFEL

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JINR BINP INR

IHEP

- Production, testing and installation of the - Cryogenic equipment GU University of Gothenburg, Gothenburg XATL1 transfer line - Power supply (Sweden) - Vertical cryostats - Magnetic bottle electron spectrometer INR Institute for Nuclear Research at the IFJ-PAN Henryk Niewodniczański Institute Russian Academy of Sciences, Moscow MSL Manne Siegbahn Laboratory of of Nuclear Physics of the Polish Academy of (Russia) Stockholm University, Stockholm (Sweden) Sciences, Kraków (Poland) - Design, production and delivery of - Measurement of magnets - Testing of all superconducting cavities, transverse deflecting structures and - Design, construction and delivery of magnets and accelerator modules electron beam diagnostics temperature sensors for the undulators

JINR Joint Institute for Nuclear Research, CELLS Consortium for the Exploitation of the Physto Department of Physics of Stockholm Dubna (Russia) Synchrotron Light Laboratory, Barcelona University, Stockholm (Sweden) (Spain) - Design, production, testing and delivery - Configuration, validation and delivery of of three MCP-based detectors - Seven mechanical support systems for the timing and synchronisation system undulators IHEP Institute for High Energy Physics, UU Uppsala University, Uppsala (Sweden) Protvino (Russia) CIEMAT Centro de Investigaciones Energéticas, Medioambientales y - Design, production and delivery of a - Design, production and installation of Tecnológicas, Madrid (Spain) laser-controlled sample injector, including cryogenic systems for the accelerator laser heating - Design, production and installation of the - Design, production, testing and delivery - Secondment of physicists for equipping beam stops of undulator intersections the structural biology measuring station - Design and production of NIIEFA D.V. Efremov Institute of Electro­ superconducting beamline magnets PSI Paul Scherrer Institute, Villigen physical Apparatus, St. Petersburg (Russia) (Switzerland) UPM Universidad Politécnica de Madrid, - Design, production and delivery of Madrid (Spain) - Design, production and installation of normal-conducting magnets the beam position monitors and intra- - Design, production, testing and delivery bunchtrain feedback systems BINP Budker Institute of Nuclear Physics, of the power supply for superconducting Novosibirsk (Russia) magnets The in-kind contributions are the result of - Design, production and testing of cooperations between institutes, and there KTH Royal Institute of Technology, Stockholm magnets, vacuum components and is some overlap in activities between the (Sweden) power supply partners. - Design, production and construction - Investigation of X-ray lenses and cooling of test stands for superconducting systems accelerator modules

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A bike ride through the X-ray laser

Two schoolboys explore the European XFEL

in the tunnel or something falls on our heads. When we arrive at the entrance building of the X-ray laser on the DESY campus, each of us also gets a “self-rescuer”. It’s a self-contained breathing apparatus that looks like a snorkel with a bag, and it enables you to go on breathing for half an hour if a fire should break out in the tunnel. We riday, 19 February, is a grey also get goggles to protect our eyes day. But at least it’s not from smoke. Frank demonstrates raining as we set out on our the equipment, a bit like a flight F bike ride down the road from attendant showing you how to use Hamburg-Sülldorf to Bahrenfeld. the oxygen masks in a plane. Our destination is a long tunnel for Finally, our tour begins. In a research facility that is expected the entrance hall is a shaft that’s to generate 27 000 X-ray flashes per almost 40 metres deep and is second. At this point, we can’t really securely protected by a railing. A imagine it. We’re looking forward to huge indoor crane hanging from the experience, a bit excited, though the ceiling is used to transport also exhausted from the past week heavy loads down the shaft. This at school. crane is very important, because We arrive at Albert-Einstein- all the components for the particle Ring and the office buildings of accelerator that is being built down transport loads weighing several European XFEL GmbH, where we there have to go down this shaft tonnes but also jack them up, have an appointment with Frank and be loaded directly on a special because the accelerator hangs from Poppe from the PR group. He’s going transport vehicle. This includes the ceiling of the tunnel. To do all to ride through the tunnel with us the yellow pipes weighing several that, the Mullewupp needs lots of and explain the X-ray laser that tonnes that contain the components power, so it has gigantic batteries – is being constructed inside it. But of the accelerator itself. Later on, using a petrol engine would be too there’s no tunnel in sight. First of we see this special vehicle in the hazardous inside the tunnel. all, we’re given our equipment and tunnel. It’s called the Mullewupp So, down we go – into the a lecture on safety. Each of us gets (which means “mole” in the local tunnel. Using our access cards, we an access card and a pair of rubber dialect) and it looks like a yellow pass through the safety barrier and boots with steel caps, because mining locomotive. On its 360 degree push our bikes into the lift, which there’s still a construction site at the tyres it can move in any direction takes us down seven stories. The end of the tunnel and safety shoes from a standing position. That’s accelerator tunnel is built like an are mandatory. We also have to wear an important skill when it has underground train tunnel. It’s a helmets, in case we bump our heads to manoeuvre inside the narrow round concrete pipe with a floor, against the technical equipment tunnel. In addition, it can not only completely straight, and it’s so

28 ZOOM

ride our bikes very carefully. There are no more undulators here. To our right is only the beam pipe, through which the X-ray laser radiation flies, and lots of testing devices that are used to monitor the light to see if it fulfils all the quality requirements. At last, we come to the end of the 57 000 euros each. They are part tunnel and to another door. We of the Russian contribution to the push our bikes through it, out of the European XFEL. The programme’s tunnel and into the underground partner countries don’t just experiment hall. This hall is as contribute money to build the X-ray big as a football field, and several laser; they also provide important measuring huts are now being components such as these magnets. built inside it. This is where the After travelling the first two researchers will be looking at atoms kilometres through the accelerator and filming chemical reactions. In tunnel, we reach a plywood door. At one of these huts, which has thick that point, we are in a bleak-looking concrete walls, they will conduct operations building located directly experiments under extremely high under the Osdorfer Born housing pressure and at high temperatures estate. This is where the tunnel – that is, under the same conditions divides into two branches, and from that exist in the interiors of planets. here on the electrons will be used to We push our bikes into the generate the X-ray laser flashes that lift and it takes us back to the long that you can’t see the end of the researchers are interested in. surface, where they are building it. Yellow accelerator modules are We ride our bikes into the labs and offices at the moment. hanging from the ceiling of the right tunnel on the right. A few of the We ride our bikes to the exit, give half of the tunnel. The electrons yellow structures in which the light back our helmets, rubber boots and could already start flying here – but flashes will be generated are already self-rescuers, and find ourselves they wouldn’t get very far, because standing here. It’s hard to remember standing in the town of Schenefeld, construction is still in full swing. what they’re called. Demulators? right next to a big tennis complex. The temperature in the modules is Odolators? Emulators? No, these are By now it’s dark outside. We say minus 271 degrees Celsius so the undulators. Inside them, alternating goodbye to Frank and ride our bikes electricity can flow without any magnets force the electrons to travel home. It’s been an exciting trip, resistance. In addition, the electrons along a slalom course and radiate but it’s also been very tiring. We’ve fly through a vacuum so that they X-ray flashes. Undulators are strong seen a lot and learned a lot. And don’t bounce against anything and magnets that can’t be turned off, so someday we’d like to go back down can be accelerated to almost the your watch may get stuck on one of into the tunnel – this time with our speed of light – 300 000 kilometres them if you bring it too close. skateboards. per second. That’s very hard to The yellow-orange undulators imagine. are produced in Germany and Spain. Vincent van Beusekom and Louis Wild are In the left half of the tunnel, There’s also another undulator that sixth-formers at their secondary school, the there’s a path for the Mullewupp really stands out because of its neon Marion Dönhoff Gymnasium in Hamburg- Blankenese. When they’re not outdoors on and for our bikes. We’ve got to be yellow-green colour. It comes from their bikes or longboards, they like to play careful to travel in a really straight China, and it works really well, but Minecraft. They’re planning to make a film line and not bump into anything. the Chinese somehow got the colour about the X-ray laser facility using the images Riding through the tunnel is a weird wrong. It really looks weird! they recorded with their GoPro cameras. and exciting experience! To our right Then we come to yet another are the yellow modules and lots place where the tunnel divides into of extremely large magnets. Frank several branches. The two original explains that these magnets will tunnels branch into five tunnels in help to bundle the electron beam. all, and each of these tunnels leads Two bright blue “dipole” magnets to various measuring stations. Our are larger than the others. They tunnel eventually becomes very come from St. Petersburg and cost narrow and warm, and we have to

29 femto 01/16 SPECTRUM

hen illuminated a metal compound incorporating with an intense football-shaped fullerenes, which infrared laser, tiny normally becomes superconductive metallic, football- at a temperature of around minus Picture: J.M. Harms, MPSD Picture: W like molecules lose their electrical 250 degrees Celsius. However, resistance at comparatively when the material was illuminated elevated temperatures. This was with the infrared laser, it became discovered by a team of physicists superconductive for a brief moment led by Daniele Nicoletti from at minus 170 degrees Celsius. the Max Planck Institute for the Back in 2013, researchers of the Structure and Dynamics of Matter institute had shown that a certain at the DESY campus in Hamburg. ceramic, when subjected to infrared Such experiments should enable a laser pulses, became superconductive more precise understanding of the for a fraction of a second even phenomenon of superconductivity. at room temperature. Given that The alkali fulleride K C , which contains football-like mole- 3 60 At present, superconductors fullerenes have a relatively simple cules comprising 60 carbon atoms, can be induced to lose its electrical resistance at a temperature as high as minus are mostly used in special applica­ chemical composition, the scientists 170 degrees Celsius by subjecting it to intense laser flashes. tions. Even the best of these hope that these new experiments will materials have to be cooled to minus enable them to better understand 70 degrees Celsius before they lose the phenomenon of light-induced, their electrical resistance, so their short-term superconductivity at Footballs with use is restricted to specialised relatively high temperatures. Such areas such as the magnets for insights could help scientists develop MRI scanners, fusion plants or a material able to conduct electricity no resistance particle accelerators. The Max without loss at room temperature Planck physicists from the group of without any optical excitation. Signs of light-induced superconductivity institute director Andrea Cavalleri

in buckminsterfullerenes investigated the fulleride K3C60, Nature, 2016; DOI: 10.1038/nature16522

California to investigate exploding Exploding nanoparticles of frozen xenon. The minuscule particles had a diameter of some 40 nanometres, around nanoparticles 1000 times thinner than a single human hair. “The nanoparticles

Scientists film nanocosmos with unprece- were superheated by means of SLAC Gorkhover, Tais Picture: dented spatial and temporal resolution intense radiation from an infrared laser and made to explode in a vacuum chamber,” explains DESY sing an X-ray supermicro­scope, a researcher Jochen Küpper from German–US team of scientists led by the team. The X-ray flashes were Tais Gorkhover from Berlin Technical precisely timed to capture images U University and Christoph Bostedt from of various stages of the explosion. Argonne National Laboratory has filmed the The experiment was repeated over Three stages of the explosion of a xenon explosion of individual nanoparticles in ultraslow and over, each time with a new nanoparticle, captured as diffraction images motion. In the process, they were able for the first nanoparticle and a slightly greater (right) by means of an X-ray laser. The state of the sample (left) can be calculated from the time ever to achieve a spatial resolution better delay before the X-ray flash. These diffraction patterns. than eight nanometres combined with a temporal temporally staggered snapshots resolution of 100 femtoseconds. A nanometre were then assembled to make a film is one millionth of a metre, a femtosecond one of the explosion. quadrillionth of a second. The research team used the LCLS X-ray Nature Photonics, 2016; DOI: 10.1038/ laser at SLAC National Accelerator Laboratory in NPHOTON.2015.264

30 femto 01/16 SPECTRUM A new

Schematic Picture: Thomas Seine, EMBL/CFEL Picture: nanomaterial representation of the beam from a free- A nanocomposite with medical and electron laser hitting a protein crystal in product applications the peroxisome of a yeast cell amburg researchers have developed a new nanomaterial that combines a number of desirable properties and thereby offers potential H applications in the fields of medical technology Scientists X-ray and manufacturing. On the smallest scale, the structure of the new material resembles that of biological hard tissue, such as mother of pearl and dental enamel. It consists of protein crystals uniformly sized iron oxide nanoparticles with a coating of oleic acid. inside cells In previous work with this material, the bonds between the oleic acid molecules were very weak and based on New approach could make it easier to determine Van der Waals forces. By means of drying, hot-pressing the structure of biomolecules and controlled heat treatment, the scientists have now managed to create a much stronger bond between the oleic acid molecules, thereby decisively improving the cientists from the European Molecular Biology nanocomposite’s mechanical properties. This new class Laboratory (EMBL) have teamed up with researchers of material might be suitable for filling dental cavities, for from DESY and the SLAC National Accelerator example, or manufacturing watch cases – applications S Laboratory in California to X-ray naturally produced requiring a material that is both hard and non-breakable. protein crystals in biological cells. The study, which was carried The scientists from the Hamburg University of out using the LCLS X-ray laser at SLAC, shows that these Technology (TUHH), the University of Hamburg, the natural crystals can be used to determine the spatial structure Helmholtz Centre Geesthacht and DESY presented their of the proteins. novel nanocomposite in the journal Nature Materials. Crystallography enables scientists to study the atomic As oleic acid is frequently used when processing other structure of proteins. First, however, they need to produce a nanoparticles, this new method could potentially crystal from the biomolecule under investigation. “Producing improve the mechanical properties of a great many protein crystals in the lab for crystallography experiments other nanocomposites as well. is not always easy,” says EMBL researcher Daniel Passon. “So imagine if we could get cells to do this for us: a tiny crystal Nature Materials, 2016; DOI: 10.1038/NMAT4553 factory in a cell!” For a structural biologist, growing protein crystals is all part of the job. Less well known is the fact that certain organisms naturally produce crystals within their cells. In certain yeast cells, for example, cell organelles known as peroxisomes pack alcohol oxidase molecules tightly together The new material under a to form crystals. It was this natural crystal production that scanning electron micro- enabled the researchers to determine the structure of the scope. It is made up of alcohol oxidase molecule. Furthermore, results were better uniformly sized iron oxide Picture: TUHH Picture: when the crystal was left within the cell rather than being nanoparticles. removed beforehand for X-raying. The researchers now hope to be able to harness the natural ability of the peroxisome in order to induce it to produce crystals of other proteins.

International Union of Crystallography Journal, 2016; DOI: 10.1107/ S2052252515022927

31 femto 01/16 SPECTRUM An optical funnel Picture: J.M. Harms, MPSD Picture: for nanoparticles

New method promises more precise delivery of biological samples into X-ray laser beams

Artist’s impression of the molecular motion of the light-sensitive part esearchers have constructed an optical funnel that of rhodopsin can precisely deliver a stream of proteins, viruses or other nanoparticles into the tightly collimated beam R of an X-ray laser for analysis. The funnel consists of Molecular a specially modified light beam with a helical wavefront. This produces a dark region at the centre of the beam, where the light intensity falls to zero. An optical lens gives the beam its breakdance funnel-like shape. In contrast to conventional optical traps, the funnel uses Our sense of vision is based on highly choreographed, thermal forces to control the particles. Whenever a particle ultrafast molecular motions gets too close to the wall of the optical funnel, it heats up on the side closest to the wall. Air molecules colliding with the particle on the warm side are repelled with greater momentum he visual process is based on the detection of light than those on the cold side. This momentum imbalance results by a pigment in the retina called rhodopsin or, in a so-called photophoretic force, which pushes the particle alternatively, visual purple. Investigations by a team from the hot to the cold side and thus toward regions of lower T of scientists led by R. J. Dwayne Miller from the Max light intensity. Planck Institute for the Structure and Dynamics of Matter The team, which was led by Andrei Rode from the and the University of Toronto in Canada have shown that Australian National University in Canberra and included the primary photochemical step of this process operates at DESY researchers from the Center for Free-Electron Laser a much faster speed than previously thought. Science (CFEL) and the Centre for Ultrafast Imaging (CUI), Rhodopsin gets its light sensitivity from a repeating tested their concept with tiny graphite beads between 12 and chain of single- and double-bonded carbon atoms. 20 micrometres in diameter. The advantage of this method is The absorption of a photon causes an extremely short, that the photophoretic forces can be much stronger than the momentary weakening of a specific double bond, resulting direct optical forces in conventional optical traps. Moreover, in a rotation about that bond. Until recently, scientists particles spend most of the time in the dark region of the were unable to precisely determine the speed of this funnel, which prevents them from the potentially damaging so-called isomerisation. With the advent of femtosecond effects of heating up. lasers, however, it was shown that the process takes place within at most 200 femtoseconds. A femtosecond is one Physical Review Applied, 2015; DOI: 10.1103/PhysRevApplied.4.064001 quadrillionth of a second. Using a highly sensitive technique from the field of ultrafast spectroscopy, the team under Max Planck Director Miller and Oliver P. Ernst from the University of Toronto looked again at the isomerisation reaction of bovine rhodopsin and showed that the process occurs over a timescale of 30 femtoseconds. “It turns out that the primary step of vision is nearly ten times faster than anyone thought,” says Miller, “and that the atomic motions are all perfectly choreographed by the protein.” Temporal analysis of the experimental data revealed a molecular Particles inside the breakdance comprising localised stretching, wagging and optical funnel are torsional motions. heated on the sides and thereby directed into the dark central area.

Nature Chemistry, 2015; DOI: 10.1038/nchem.2398 Applied N. Eckerskorn Picture: et al., Phys. Rev.

32 femto 01/16

Picture: Rob Meijers, EMBL Picture: femtomenal

The entire protein complex is produced PETRA III by a single gene.

FLASH

LINAC II European XFEL PIA One gene, DESY two proteins,

one complex HERA

ormally, a gene produces exactly one protein. Occasionally, it may produce two. But, as Rob Meijers, 16 288 metres group leader at the Hamburg outstation of the N European Molecular Biology Laboratory (EMBL) on the DESY campus, points out, to see two proteins produced from of tunnels the same gene that then bind together to form a complex – that is truly unique. Meijers and his team were investigating viral enzymes that degrade the cell walls of Clostridium he accelerator tunnels on the DESY campus bacteria. They discovered that there is both a short and a long and in the surrounding area add up to precisely variant of the enzyme, each produced by the same gene. This 16 kilometres and 288 metres in length. Many of is because the gene has two different starting points and can T them are linked together to form an underground therefore produce proteins of different lengths. “This study network through which ultrafast particles must be guided shows how two such proteins from the same gene form a with the utmost precision. For example, electrons destined complex, and how the shorter protein regulates the full-length for the PETRA III storage ring pass through a cascade of protein,” says Meijers. “To our knowledge, that has never been three accelerators and need to be delivered from one to the seen before.” next with an accuracy of 50 picoseconds – a picosecond is The interaction between these two proteins plays a key a millionth of a millionth of a second. All in all, the tunnels role in how the viral enzymes, known as endolysines, destroy that these electrons fly through measure 3.5 kilometres the cell wall of the Clostridium bacteria. The species of the in length. While a high-speed train moving at 230 km/h genus Clostridium include some dangerous pathogens. Viruses would need 54 seconds to travel this distance, the particles that attack bacteria – so-called bacteriophages – could provide are about four million times faster. Travelling at almost a new weapon in the fight to combat bacterial infections. This the speed of light, they could cover this distance in just makes them, and particularly their enzymes, very interesting 12 microseconds (millionths of a second) – if they weren’t objects of research. forced to take multiple turns in the pre-accelerators before entering PETRA III. Journal of Biological Chemistry, 2015; DOI: 10.1074/jbc.M115.671172

33 femto 01/16 CAMPUSCAMPUS Picture: DESY, Heiner Müller-Elsner DESY, Picture:

The fast DESY control technology also has Licensed to big potential for industrial applications. measure

A new electronic standard conquers the market

article accelerators are such systems can be constructed physicists and DESY-TT have been highly complex facilities, with components either bought in pushing its commercialisation often several kilometres or produced in-house. and its use in industry. It was a P in length and packed with According to DESY accelerator new departure not only for the high technology. It takes very fast expert Holger Schlarb, three of researchers but also for DESY. and extremely precise systems to the already existing standards The team first looked at the control these particle race tracks would, in principle, have been standard that most closely approxi­ – systems that are capable of suitable for operating a particle mated their requirements: MicroTCA processing many datasets in parallel. accelerator. There was only one (Micro Telecommunications Such systems must run problem- problem: “Ultimately, none of them Computing Architecture). “This is free for at least ten years, 24 hours was suitable for DESY’s future a very common industry standard,” a day. Even if a power supply unit development.” This development Schlarb explains. “It comes from the fails, everything else must continue includes the 3.4-kilometre-long telecoms sector and does everything to function without interruption. European XFEL X-ray laser, currently we want, except for one thing: Various electronic standards have under construction in western recording extremely high-quality been established in recent decades Hamburg. For this reason, Schlarb analogue data.” Unfortunately, that to facilitate the development of and his team helped to developed is absolutely essential for research systems capable of meeting such a new industry standard and took with particle accelerators. The DESY specifications. These electronic it to marketability together with physicists therefore collaborated standards provide a uniform the DESY Technology Transfer (TT) with other institutes and industrial description on the basis of which group. For the last three years, the partners to add this missing

34 femto 01/16 CAMPUS

function – the ability to carry out markets,” says Schlarb. “The new analogue measurements. standard impressively shows how A new industry standard was science and industry can benefit established – MicroTCA.4 – and from the innovative power of on this basis, the DESY team then research,” adds Katja Kroschewski, developed a system of control the head of DESY-TT. boards capable of processing both With one patent and analogue and digital signals. With 18 licensing agreements based this setup, over 100 parameters on this development work, the can be read out in real time investment in the new standard several hundred million times a is already paying off. “This second. Thanks to an integrated way, we generate income and management system, everything have the opportunity to develop can be operated and maintained things further,” says Michael remotely. What’s more, the system Fenner, a development engineer is scalable across a range of at DESY. And even if the process applications, i.e. it is suitable for is progressing too slowly for the small units all the way up to highly researchers themselves, industry complex, large-scale facilities. expert Heiko Körte predicts a highly promising future. “We’re already using MicroTCA.4 as the “We want to basic standard for a whole range of projects,” says Körte, Director of establish Sales & Marketing at the systems DESY scientist Holger Schlarb was manufacturer N.A.T. in Bonn, ­MicroTCA.4 in extensively involved in the development Germany. This includes traffic of the MicroTCA.4 standard. the scientific management systems and various wireless applications for fixed and community and mobile networks. The standard also looks set to play a growing role in in industrial the fields of medical technology and markets” disaster management. eight years.” Compared to the VME, Holger Schlarb, DESY Compact PCI and VPX standards, “We’re already Körte estimates that MicroTCA now This makes the new standard an has a market share, with respect interesting proposition not only using MicroTCA.4 to new applications, of between for the scientific community but 30 and 35 percent. A market study also for industry, where there are as the basic from 2014 put annual growth at many potential fields of application. standard for nine percent. MicroTCA.4 is part These include telecommunications, of this story. online inspection, aviation, a whole range N.A.T. was a key partner in medical technology and precision the development of MicroTCA metrology. For this reason, the of projects” and has meanwhile switched to Helmholtz Association, DESY Heiko Körte, N.A.T. this standard for 85 percent of its and industrial partners put up products. Of that, 12 percent are four million euros in 2012 to “This standard is ideal in a situation based on MicroTCA.4 – a figure promote its commercialisation after an earthquake, for example, that is set to increase in future. and use in industrial companies. when you need to set up base Körte is optimistic that the new It was unfamiliar territory for stations for mobile communications, standard will establish itself on the researchers, who since then or for setting up mobile-network the market. Companies need a bit have been attending trade fairs, transmission stations in areas of time to become familiar with giving workshops and acting as around the world with little or no the new standard and its possible consultants. “We want to establish infrastructure,” says Körte. “The applications, he explains: “But that’s MicroTCA.4 in the scientific MicroTCA standard has been a a transitional process. It will take a community and in industrial remarkable success over the past few years yet, but less than ten.”

35 femto 01/16 CAMPUS An unknown oxygen source in the Earth’s mantle

Discovery of new iron oxides provides decisive clues

Structure of the newly

discovered iron oxide Fe25O32 Picture: Elena Bykova, University of Bayreuth Picture:

xperiments using special high-pressure which is the end product of many geological cells have revealed the existence of two processes and the main source of iron for our new iron oxides. The discovery by Elena civilisation,“ explains Bykova. During the past E Bykova from the University of Bayreuth in five years, however, scientists have discovered Germany and her team points to the existence of other iron oxides that form at high pressures a large and hitherto unknown source of oxygen and temperatures. To further investigate the

in the Earth’s lower mantle, raising a number behaviour of haematite and magnetite (Fe3O4), of interesting questions. What happens to the Bykova and her colleagues used a special oxygen, for example? Does it react with the pressure cell at DESY’s X-ray light source surrounding rock? Or does it rise towards the PETRA III. surface? And how does it affect geochemical “In this so-called diamond anvil cell, a processes within the Earth system? minute sample can be compressed between two Iron oxides in nature take on different forms. diamonds to several hundred thousand times

“The most common iron oxide is haematite, Fe2O3, the atmospheric pressure while a meticulously

36 femto 01/16 CAMPUS

Crust temperature conditions correspond to those in Upper mantle a depth of roughly 1500 kilometres below the surface of the Earth. At an even higher pressure Subduction zone Transition zone of 70 gigapascals, corresponding to about 1670 kilometres below the surface, magnetite Lower mantle decomposed and another new iron oxide with the formula Fe O formed. The formation of both of Fe5O7 + O2 25 32 these previously unknown compounds leads to Fe O + O 25 32 2 the release of oxygen. Although iron oxides do not normally exist in the bulk of the Earth’s lower mantle, they can Outer core be transported there via subduction zones, where one tectonic plate dives under another. Haematite and magnetite are major components of so- Iron oxides can be carried deep into the Earth’s called banded iron formations and ironstones, mantle via subduction huge sedimentary rock formations occurring zones. At sufficient on all continents. These formations may be up pressure and heat, Inner core to several hundred metres thick and hundreds haematite and magnetite of kilometres long. Deposited in the world’s decompose to form oceans about two billion years ago, banded iron new iron oxides, thereby releasing large quantities formations form part of the ocean floor and are of oxygen. The fate of recycled into the Earth’s interior by subduction this oxygen has yet to be aligned laser can also heat the sample to processes, which can carry them to great explored. several thousand degrees Celsius through the depths, possibly even as far as the core–mantle transparent diamond anvils,” explains DESY boundary region. scientist Hanns-Peter Liermann. At the same time, As the team observed, at conditions the exceptionally bright and fine X-ray beam corresponding to the middle of the Earth’s lower of PETRA III can track structural changes in the mantle, haematite and magnetite decompose, sample. Similar measurements were also made releasing huge amounts of oxygen-rich fluid at the European Synchrotron Radiation Source (oxygen is usually liquid under these conditions). (ESRF) in Grenoble, France, and at the Advanced “We estimate that this source so far provided Photon Source (APS) in Chicago, USA. an amount of oxygen equivalent to eight to ten times the mass of oxygen in the atmosphere,“ says Bykova. “That’s a surprise, and it is not quite “In this so-called clear what happens with the oxygen down there.” The oxygen-rich fluid could either locally diamond anvil cell, a oxidise surrounding rocks or migrate to the minute sample can be transition zone, or even to the upper mantle. “This remains to be explored,” says co-author compressed between Maxim Bykov of the University of Bayreuth. “For now, we can only say that there is a huge source two diamonds to of oxygen in the mantle that can significantly several hundred affect geochemical processes by changing oxidation states and mobilising trace elements. thousand times the This will open a large new field of modelling.” The discovery of the new iron oxides thus atmospheric pressure” not only adds to the knowledge about the Hanns-Peter Liermann, DESY fundamental characteristics of these substances, underlines Bykov. “Our work shows that we When the scientists applied a pressure of maybe miss significant parts of the processes more than 67 gigapascals (about 670 000 times in the Earth. Subducted slabs can apparently the standard atmospheric pressure) to their produce unexpected things. The effects on Earth’s haematite samples and heated them to more global dynamics, including climate variations,

than 2400 degrees Celsius, Fe2O3 decomposed have to be investigated.”

and formed Fe5O7, a new iron oxide that had not been seen before. These pressure and Nature Communications, 2016; DOI: 10.1038/NCOMMS10661

37 femto 01/16 CAMPUS

for the miniature accelerator A particle modules is silicon. “The advantage is that we can draw on the highly advanced production technologies that are already available for silicon accelerator on microchips,” explains Hartl. DESY will bring its vast know- how as an international leader in a microchip laser technology to the project, which has already paid off in Innovative development is expected to other collaborations involving the facilitate access to accelerator technology University of Erlangen-Nürnberg. There, Hommelhoff’s group showed that, for slow electrons, a n a new development that for many purposes, at least in the microstructured accelerator module would have been barely short term. However, this advance is able to achieve higher accelerating conceivable only a short time could mean that accelerators will gradients than RF technology. I ago, scientists are now working become available in areas that have Byer’s group had independently on a miniature particle accelerator previously had no access to such demonstrated the same effect for the size of a microchip. The inter­ technologies. fast, relativistic electrons. national project is being funded by “This prototype could set However, it is still a long way a grant of 13.5 million US dollars the stage for a new generation from an experimental setup in a (12.6 million euros) from the Gordon of ‘tabletop’ accelerators, with laboratory to a working prototype. and Betty Moore Foundation. DESY unanticipated discoveries in biology Individual components of the and the University of Hamburg are and materials science and potential system will have to be developed among the partners involved in this applications in security scanning, from scratch. Among other things, international project, headed by medical therapy and X-ray imaging,” DESY is working on a high- Robert Byer of Stanford University explains Byer. precision electron source to feed (USA) and Peter Hommelhoff of the The project is based on advances the elementary particles into the University of Erlangen-Nürnberg in nanophotonics, the art of accelerator modules, a powerful (Germany). Within five years, creating and using nanostructures laser for accelerating them, and an they hope to produce a working to generate and manipulate light. A electron undulator for generating prototype of an “accelerator on a laser producing visible or infrared X-ray radiation. The interaction chip”. light is used to accelerate the between the miniature components “The impact of shrinking electrically charged elementary is also not yet a routine matter, accelerators can be compared to particles, rather than the radio especially when it comes to joining the evolution of computers that frequency (RF) waves currently up several accelerator modules. once occupied entire rooms and used. The wavelength of this laser The SINBAD (Short Innovative can now be worn around your radiation is some ten thousand Bunches and Accelerators at DESY) wrist,” says Hommelhoff. Large- to one hundred thousand times accelerator development lab that scale facilities will remain essential shorter than that of the radio waves. is currently being set up at DESY “The advantage is that everything is will provide the ideal testing up to fifty times smaller,” explains environment for the miniature DESY scientist Franz Kärtner, who accelerator modules. “SINBAD is also a professor at the University will allow us to feed high-quality of Hamburg and the Massachusetts electron beams into the modules, Institute of Technology (MIT) in the to test the quality of the beams USA and a member of Hamburg’s and to work out an efficient way Centre for Ultrafast Imaging (CUI). of coupling the laser. DESY offers “The typical transverse unique opportunities in this respect,” dimensions of an accelerator cell explains DESY accelerator expert shrink from ten centimetres to one Ralph Aßmann. micrometre,” adds Ingmar Hartl, Picture: SLAC National Accelerator Laboratory Picture: head of the laser group in DESY’s Three “accelerators on a chip” made of Photon Science Division. At the silicon are mounted on a clear base. moment, the material of choice

38 femto 01/16 CAMPUS Why van Gogh’s Sunflowers are wilting

X-ray investigation shows how chrome yellow darkens

he colour of Vincent van one at the Seji Togo Memorial Gogh’s famous Sunflowers is Sompo Japan Nipponkoa Museum of changing over time, because Art in Tokyo and one at the Van Gogh T of the mixture of pigments Museum in Amsterdam. Two small used by the Dutch master. Evidence paint samples, measuring less than for the process comes from a one millimetre each, were taken detailed X-ray investigation of the from the painting in Amsterdam Sunflowers version at the Van Gogh and examined using DESY’s X-ray Museum in Amsterdam. A group of source PETRA III. “The analysis Credit: Van Gogh Museum, Amsterdam (Vincent van Gogh Foundation) (Vincent Gogh Museum, Amsterdam Van Credit: scientists headed by Letizia Monico shows that the orange-yellow hues from the Institute of Molecular mainly contain the light-fast version Sunflowers, 1889, Science and Technology (CNR- of chrome yellow, whereas the Vincent van Gogh (1853–1890) ISTM) of Perugia, the University of light-sensitive type is mainly found Perugia in Italy and the University of in the pale yellow areas,” reports Antwerp in the Netherlands shone Gerald Falkenberg, who is in charge of the paint. “At least at the two X-rays from DESY’s light source of the beamline where the X-ray sites from which the paint samples PETRA III through tiny particles diffraction measurements were were taken, a colour change has of paint taken from the painting. carried out. occurred in Sunflowers as a result The study identifies areas of the of the reduction of chrome yellow,” painting that should be monitored says Monico. This suggests that the particularly closely for any changes. painting Sunflowers may originally Vincent van Gogh (1853–1890) “This study also have looked different from what we is famous for his use of bright has broader see today. yellow colours. The Dutch painter The scientists used a mobile used chrome yellows, a class of implications for scanner to identify those parts of compounds consisting of lead, the painting which ought to be chromium and oxygen. “There are assessing the monitored particularly closely for different shades of the pigment, and possible changes. “Since chrome not all of them are photochemically colours of other yellow pigments were widely used stable over time,” explains Monico. works of art” by late 19th-century painters, this “Lighter chrome yellow has sulphur Koen Janssens, University of Antwerp study also has broader implications mixed into it and is susceptible to for assessing the colours of other chemical degradation when exposed works of art,” emphasises Koen to light, which leads to a darkening At the European Synchrotron Janssens from the University of of the pigment.” Radiation Facility (ESRF) in Grenoble, Antwerp, who was extensively The scientists examined the the team examined the chemical involved in the study. Sunflowers painting, which dates state of the paint samples. When back to 1889, to determine whether light-sensitive chrome yellow Angewandte Chemie, 2015; DOI: 10.1002/ van Gogh had used different types darkens, the chromium is reduced ange.201505840 of chrome yellow when painting it. from its highest oxidation state CrVI He produced three versions of the to CrIII. The scientists were indeed painting, one of which is on display able to detect a relative proportion at the National Gallery in London, of 35 percent CrIII on the surface

39 By Johannes Kretzschmar femtocartoon Our favourite This Danish astronomer is not very scientists! …is definitely well known today, but we believe My own personal Tycho Brahe. that after his death his observations favourite… strongly influenced Kepler’s laws Today I’d like of planetary motion. to talk about a completely different Got Over my topic… data? dead body!

He also generated For example, we believe he died of a burst bladder. The best anecdote many bizarre anecdotes He urgently needed to relieve himself but no one was comes from his that go all the way allowed get up before the king had left the table. student years. to his death. Apricot or fruit I can’t decide! This premise is sorbet pudding… absolutely false, Tycho!

The argument with another student Little is known about But the loss of his And that was about a mathematical proof escalated the argument or nose suggests that how he got his into a challenge to solve this conflict Brahe’s math skills his fencing skills copper nose! in the traditional way. at the time… were limited. 6 a.m. tomorrow I’ll be En garde! Ouch! behind the house! there!

Yech! Did I promise too much?

In view of some of the scientific Just think of the potential offered discourse we hear today, I often wish by all the laser labs we have today! MMMMMPFFFFF! we could take Brahe as an example… 0.045 is Not with this significant! p-value! Hypothesis. Antithesis.

Safety Officer

40 femto 01/16 femto 01/16 Imprint

femto is published by Translation Deutsches Elektronen-Synchrotron DESY, TransForm GmbH, Cologne a research centre of the Helmholtz Association Ilka Flegel

Editorial board address Cover picture Notkestraße 85, 22607 Hamburg, Germany Dirk Nölle, DESY Tel.: +49 40 8998-3613, fax: +49 40 8998-4307 e-mail: [email protected] Printing and image processing Internet: www.desy.de/femto Heigener Europrint GmbH ISSN 2199-5192 Copy deadline Editorial board March 2016 Till Mundzeck (responsible under press law) Ute Wilhelmsen

Contributors to this issue Frank Grotelüschen, Kristin Hüttmann

Design and production Diana von Ilsemann

The planet simulator A new high-pressure press at DESY’s X-ray source PETRA III can simulate the interior of planets and synthesise new materials. The Large Volume Press (LVP), which was installed in collaboration with the University of Bayreuth in Subscribe to Germany, can exert a pressure of 500 tonnes on each of its three axes. That corresponds to 300 000 times the atmospheric pressure or the pressure that reigns 900 kilometres under the Earth’s surface. The colossal device is femto free of charge! 4.5 metres high and weighs 35 tonnes. Depending on the desired pressure, samples with a size of up to one cubic centimetre can be compressed. That’s www.desy.de/femto or +49 40 8998-3613 roughly the size of a normal die for board games, and in the field of high- pressure experiments it’s very impressive. The LVP is the world’s biggest press installed at a synchrotron.

The DESY research magazine

Cover picture In the new European XFEL X-ray laser, electrons are accelerated to almost the speed of light and then made to generate intense ultrashort X-ray flashes. The accelerator elements are housed in yellow pipes that are 12 metres long and almost one metre thick. In a test hall at DESY, the complex components are carefully checked before they are installed in the X-ray laser facility’s accelerator tunnel. Germany’s largest scientific organisation. scientific largest Germany’s DESY is a member of the Helmholtz Association, universe. the onto windows new completely up open and energies to record particles X intense most the generate DESY facilities The tools. research unique are Zeuthen and Hamburg in locations its at builds and DESY develops that detectors and accelerators The biomolecules. between place take that processes vital the and nanomaterials of innovative behaviour to the particles elementary of tiny interaction the from –ranging variety its all in microcosm the DESY at to explore facilities large‑scale the use Researchers centres. accelerator particle world’s leading of the one DESY is centre research DESY The

- r ay radiation in the world, accelerate accelerate world, the in ay radiation

femto – The DESY research magazine | Issue 01/16 X-ray laser X-ray super The ZOOM The DESYresearch magazine–Issue01/16 Why van Gogh’s van Why Sunflowers are wilting are Sunflowers assemble themselves assemble Nanostructures Nanostructures Breakthrough in Breakthrough crystallography crystallography