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  • richardmitnick 10:06 am on July 25, 2016 Permalink | Reply
    Tags: , DESY, Electron injector for European XFEL exceeds expectations, ,   

    From XFEL: “Electron injector for European XFEL exceeds expectations” 

    XFEL bloc

    European XFEL

    25 July 2016
    No writer credit found

    First accelerator section successfully tested

    DESY has successfully concluded tests of the first section of the particle accelerator for the European XFEL. The so-called electron injector, which is 30 metres long, performed distinctly better than expected. The injector already completed a whole week under operating conditions. “Having gathered much valuable experience, we are now all set to start up the entire accelerator complex”, reports Winfried Decking, the machine coordinator at DESY. “This is a huge success for the entire accelerator team, together with our international partners.”

    1
    The diagnostic system produces elongated images of individual electron bunches and allows to analyse them in slices. DESY

    The bright X-ray light of the European XFEL is produced by small bunches of high-energy electrons which are brought to speed by a particle accelerator and then sent down an undulating magnetic path. At each magnetic bend in the path, the electron nunches emit X-rays which add up to a laser-like pulse in a self-amplifying manner.

    DESY is the main shareholder of the European XFEL GmbH and responsible, among other things, for building and operating the 2.1-kilometre particle accelerator. The injector is located at the very beginning of the accelerator to which it supplies tailor-made bunches of electrons. The quality of these electron bunches is crucial to the quality of the X-ray laser pulses at the experimental stations, 3.4 kilometres away. One important quality criterion is how narrowly the electron bunches can be focused. “This so-called emittance is some 40 percent better than specified”, reports Decking.

    2
    The injector is 30 metres long. Dirk Nölle / DESY

    Ten times every second, the injector produces a train of up to 2700 short bunches of electrons. To test the quality of the beam, a special diagnostic system picks out individual bunches. “We need only about four bunches per train to analyse the beam”, explains Decking. These bunches are tilted by a cavity before striking the diagnostic screen. The elongated image they leave behind as a result can be used to study the longitudinal structure of each bunch in detail. The analysis reveals the outstanding quality of the bunches.

    In the past seven months, the injector, which produced its first electron beam in December, has given the accelerator team an opportunity to get to know all major subsystems of the entire accelerator facility: “The injector includes all the subsystems that are used in the main accelerator too”, says Decking. “This meant we were able to test and familiarise ourselves with them.” All in all, he says, no major obstacles were encountered throughout the several months of its test operation. The injector went offline on Monday, so that it can be connected to the main accelerator, for which commissioning is planned to start in October 2016. The whole facility is expected to be available for experiments as from the summer of 2017.

    3
    View of DESY’s accelerator control centre, European XFEL section. Dirk Nölle / DESY

    Apart from DESY and European XFEL GmbH, the Centre national de la recherche scientifique CNRS in Orsay (France), the Commissariat à l’énergie atomique et aux énergies alternatives CEA in Saclay (France), the Istituto Nazionale di Fisica Nucleare INFN in Milan (Italy), the Narodowe Centrum Badań Jądrowych in Swierk (Poland), the Wrocław University of Technology WUT in Wrocław (Poland), the Instytut Fizyki Jądrowej IFJ-PAN in Krakow (Poland), the Institute for High-Energy Physics in Protvino (Russia), the Efremov Institute NIIEFA in St. Petersburg (Russia), the Budker Institute for Nuclear Physics BINP in Novosibirsk (Russia), the Institute for Nuclear Research INR in Moscow (Russia), the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas CIEMAT in Madrid (Spain), the Universidad Politécnica de Madrid UPM in Madrid (Spain), the University of Stockholm (Sweden), the University of Uppsala (Sweden), and the Paul Scherrer Institute in Villigen (Switzerland) are also involved in the injector.

    See the full article here .

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    XFEL Campus

    The Hamburg area will soon boast a research facility of superlatives: The European XFEL will generate ultrashort X-ray flashes—27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources.

    The outstanding characteristics of the facility are unique worldwide. Starting in 2017, it will open up completely new research opportunities for scientists and industrial users.

     
  • richardmitnick 8:02 am on July 15, 2016 Permalink | Reply
    Tags: , DESY, Focused Ion Beam Microscope   

    From DESY: “New focused ion beam strengthens nano and high-pressure science” 

    DESY
    DESY

    2016/07/07
    No writer credit found

    1
    Preparation of a double-staged diamond anvil cell with the focused ion beam microscope. Credit: Leonid Dubrovinsky, Universität Bayreuth

    2
    Natalia Dubrovinskaia and Thomas Keller in front of the new focused ion beam microscope at DESY. Credit: Sylvain Petitgirard, Universität Bayreuth

    “Nano scalpel” allows structuring of samples with nanometre precision

    A new “nano scalpel” enables scientists at DESY to prepare samples or materials with nanometre precision while following the process with a scanning electron microscope. The Focused Ion Beam, or FIB, microscope which has now gone into service also allows a detailed view of the inner structure of materials.

    2
    FIB

    The device was purchased by the University of Bayreuth, as part of a joint research project on the DESY campus funded by the Federal Ministry of Research. The FIB will be operated at the DESY NanoLab jointly with the University of Bayreuth.

    “The microscope is not only able to examine microscopic defects, cracks or point-like corrosion sites underneath the surfaces of materials, but also to machine the surface of samples with extremely high precision, on a nanometre scale,” explains Maxim Bykov, project scientist from the University of Bayreuth. A nanometre is a millionth of a millimetre. The ion beam can be used to remove material as though it were a microscopic milling machine; as a result, the combined ion beam and electron microscope is particularly interesting for a wide range of applications in nanotechnology, materials science and biology.

    “Apart from examining the structure of materials, the ability of the ion beam to remove material also leads to a wide range of different applications,” says Natalia Dubrovinskaia who is a professor at the University of Bayreuth and in charge of the joint research project (No. 05K13WC3). One example is the preparation of tiny diamond anvils, which are used to hold samples during ultra high-pressure experiments. The diamonds used for this are so small that there is no other way of preparing them. The ion beam microscope allows so-called double-staged diamond anvil cells to be prepared with nanometre precision. The ultra high-pressure experiments are carried out at DESY’s Extreme Conditions Beamline (ECB) P02.2, headed by DESY scientist Hanns-Peter Liermann.

    In addition, the device allows researchers to investigate the chemical composition of samples by measuring fluorescent radiation. “Together with the built-in milling machine, we can not only determine the three-dimensional structure, but also the distribution of the elements beneath the surface by alternately removing material and carrying out a chemical analysis, much like in 3D tomography,” adds Thomas Keller who heads the sub-division microscopy and nano structuring at the DESY NanoLab.

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 12:56 pm on June 2, 2016 Permalink | Reply
    Tags: , DESY, , Ironing out the mystery of Earth’s magnetic field   

    From DESY: “Ironing out the mystery of Earth’s magnetic field” 

    DESY
    DESY

    2016/06/01
    No writer credit found

    Scientists directly measure thermal conductivity of iron at planetary core conditions for the first time.

    1
    A cross-section of the earth with the field lines of the geomagnetic field (as simulated with the Glatzmaier-Roberts geodynamo model http://www.es.ucsc.edu/~glatz/geodynamo.html ). Illustration: DESY

    The earth’s magnetic field has been existing for at least 3.4 billion years thanks to the low heat conduction capability of iron in the planet’s core. This is the result of the first direct measurement of the thermal conductivity of iron at pressures and temperatures corresponding to planetary core conditions. DESY scientist Zuzana Konôpková and her colleagues present their study* in the scientific journal Nature. The results could resolve a recent debate about the so-called geodynamo paradox.

    The geodynamo generating the earth’s magnetic field is fed on convection in the iron-rich outer core of our planet that stirs the molten, electrically conducting material like boiling water in a pot. Combined with the rotation of the earth, a dynamo effect sets in, giving rise to the geomagnetic field. “The magnetic field shields us from harmful high-energy particles from space, the so-called cosmic radiation, and its existence is one of the things that make our planet habitable,” explains Konôpková.

    The strength of the convection in the outer core depends on the heat transferred from the core to the earth’s lower mantle and on the thermal conductivity of iron in the outer core. If a lot of heat is transferred via conduction, there is not much energy left to drive convection – and with it the earths’s dynamo. Low thermal conductivity implies stronger convection, making the geodynamo more likely to operate. “We measured the thermal conductivity of iron because we wanted to know what the energy budget of the core is to drive the dynamo,” says Konôpková. “Generation and maintenance of our planet’s magnetic field strongly depend on the thermal dynamics of the core.”

    Measurements of thermal conductivity at relevant conditions proved to be difficult in the past. Recent theoretical calculations postulated a quite high thermal conductivity of up to 150 Watts per meter per Kelvin (150 W/m/K) of iron in the earth’s core. Such a high thermal conductivity would reduce the chances of the geodynamo starting up.

    According to numerical models, a high thermal conductivity would have allowed the geodynamo effect to be supported only rather recently in the earth’s history, about one billion years ago or so. However, the existence of the geomagnetic field can be traced back at least 3.4 billion years. This geodynamo paradox has puzzled scientists. “There’s been a fierce debate among geophysicists because with such a large thermal conductivity, it becomes hard to explain the history of the geomagnetic field which is recorded in ancient rocks”, says Konôpková.

    The physicists used a specially designed pressure cell that allows to compress samples between two diamond anvils and to heat them simultaneously with infrared lasers, shining right through the diamonds. Konôpková teamed up with Stewart McWilliams and Natalia Gómez-Pérez from the University of Edinburgh and Alexander Goncharov from the Carnegie Institution in Washington DC to measure the thermal conductivity of iron at high pressure and high temperature conditions in Goncharov’s lab.

    “We compressed a thin foil of iron in the diamond anvil cell to up to 130 Giga-Pascals, which is more than a million times the atmospheric pressure and corresponds to approximately the pressure at the earth’s core-mantle boundary,” explains Konôpková. “Simultaneously we heated up the foil to up to 2700 degrees Celsius with two continuous infrared laser beams, shining through the diamonds. Finally, we used a third laser to send a low power pulse to one side of the foil to create a thermal perturbation and measured the temperature evolution from both sides of the foil with an optical streak camera.” This way the scientists could watch the heat pulse travelling through the iron.

    These measurements were conducted at several pressures and temperatures to cover different conditions of planetary interiors and to obtain a systematic investigation of the thermal conductivity as a function of pressure and temperature. “Our results strongly contradict the theoretical calculations,” reports Konôpková. “We found very low values of thermal conductivity, about 18 to 44 Watts per meter per Kelvin, which can resolve the paradox and make the geodynamo operable since the early ages of the earth.”

    *Science paper:
    Direct measurement of thermal conductivity in solid iron at planetary core conditions

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 12:15 pm on May 30, 2016 Permalink | Reply
    Tags: , DESY, , Materials made to measure   

    From DESY: “Materials made to measure” 

    DESY
    DESY

    2016/05/27

    1
    Functional building blocks of polymers, ceramics or metals are specifically assembled on the nano-, micro- or macro level in the three project areas A, B and C of the SFB 986. How this is accomplished depends on which – partly completely new – property profile the desired material shall have. Credit: TUHH

    Materials science continues to be funded as collaborative research centre

    The collaborative research centre SFB 986, entitled “Tailor-Made Multiscale Material Systems – M3” will be funded for another four years by the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft). SFB 986 is a collaboration between the Hamburg University of Technology (TUHH), the Helmholtz Centre Geesthacht (HZG), the University of Hamburg (UHH) and DESY. Overall, a sum of 13 million euros has now been granted. The second phase of funding begins on 1 July 2016.

    Since 2012, some 80 scientist have been involved in 22 projects carrying out fundamental research into a new category of materials: so-called “tailor-made multiscale material systems”. The Hamburg collaborative project provides the ideal network for top-level research into material scientific issues: researchers can draw on expertise in the field of synthesising nanoparticles (UHH) and nanophotonics (TUHH), the mechanics of small systems (TUHH and HZG) as well as scattering methods, spectroscopy and tomography (DESY and HZG). The report by the DFG particularly emphasises this “living network”. “We are very pleased that our achievements so far are being recognised by the DFG in continuing to fund the SFB. The continuation of the SFB demonstrates that we are conducting top-level research in materials science on an international level,” says Gerold Schneider, spokesman for the SFB 986 and head of TUHH’s Institute of Advanced Ceramics.

    Over the next four years, novel material systems are to be developed, displaying even better mechanical, electrical or photonic properties. For example, the Hamburg scientists are a step closer to producing a material that would be warmly welcomed by medical engineers. A newly developed manufacturing technique allows them to produce a material based on nanoparticles and organic molecules that displays high elasticity and strength, while at the same time being extremely hard. This material could one day be used for dental fillings, for example, or to manufacture watch cases. The aim is to open the door to an entirely new range of properties and structures, and to develop these to maturity.

    The researchers at DESY’s NanoLab are in charge of a subproject, examining the interfaces of oxides and organic materials, which play a key role for the outstanding properties of these materials. In addition, they are working with TUHH on a subproject regarding polymers in nanoporous materials.

    The metropolitan region of Hamburg and international materials research are being boosted in the long term by the SFB 986. This is not only demonstrated by the scientific advances being made, but also by the new master’s course in “Materials Science” which has been introduced at TUHH. At the same time, the creation of the Centre for High-Performance Materials (ZHM) at TUHH as well as other investments in the scientific field of electron microscopy, are long-term measures for establishing and strengthening this successful alliance in the field of materials research in North Germany.

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 8:38 am on May 6, 2016 Permalink | Reply
    Tags: , DESY, ,   

    From DESY: “High-speed camera snaps biosensor’s rapid reaction to light” 

    DESY
    DESY

    X-ray study reveals ultrafast dynamics of photoactive yellow protein

    1
    Inner structure of the photactive yellow protein 800 femtoseconds after the trans-to-cis isomerisation has been initiated by an ultrafast blue laser. The chromophore binding pocket is cut open and the chromophore itself is highlighted by the bulls eye. Credit: Marius Schmidt/University of Wisconsin-Milwaukee

    Using a high-speed X-ray camera, an international team of scientist including researchers from DESY has revealed the ultrafast response of a biosensor to light. The study, published* in the US journal Science, shows light-driven atomic motions lasting just 100 quadrillionths of a second (100 femtoseconds). The technique promises insights into the ultrafast dynamics of various light sensitive biomolecules responsible for important biological processes like photosynthesis or vision.

    The team lead by Marius Schmidt from the University of Wisconsin, Milwaukee used the LCLS X-ray laser at SLAC National Accelerator Laboratory in the U.S. to look at the light-sensitive part of a protein called photoactive yellow protein, or PYP.

    SLAC/LCLS
    SLAC/LCLS

    It functions as an “eye” in purple bacteria, helping them sense blue light and stay away from light that is too energetic and potentially harmful.

    For their investigation, the scientists sent a stream of tiny PYP crystals into a sample chamber. There, each crystal was struck by a flash of optical laser light and then, almost immediately after, an X-ray pulse was used to interrogate the protein’s structural response to the light at the atomic level. The structure is determined indirectly from the intricate pattern of X-ray light scattered from the crystal. By varying the time between the two pulses, scientists were able to see how the protein morphed over time. “By placing the various obtained molecular structures in order of the time delay between the optical and X-ray flashes we obtain a molecular movie of the reaction as it evolves from the first step at 100 femtoseconds to several thousand femtoseconds,” explained the first author of the paper, Kanupriya Pande, also from the University of Wisconsin and now at the Center for Free-Electron Laser Science CFEL at DESY.

    “The absorption of light leaves PYP in an excited state from which it relaxes very quickly,” explained Schmidt, the study’s principal investigator. “It does so by rearranging its atomic structure in what is known as trans-to-cis isomerisation. We’re the first to succeed in taking real-time snapshots of this type of reaction.” This type of isomerisation is also what gives vision – in that case the retinal chromophore undergoes a cis-to-trans isomerisation that ultimately leads to neuronal excitation in the eye.

    “We were able to obtain detailed structures at incredibly short time points after the initial absorption event by taking flash X-ray snapshots with the world’s brightest X-ray source,” said co-author Henry Chapman from CFEL at DESY. But, as Pande pointed out, “these are very challenging experiments, where we needed considerable innovation to assign the correct time stamps to hundreds of thousands of X-ray patterns.”

    The researchers had already studied light-induced structural changes in PYP at LCLS before, revealing atomic motions as fast as 10 billionths of a second (10 nanoseconds). By tweaking their experiment with a faster optical laser and better timing tools and sorting, they were now able to improve their speed limit 100,000 times and capture reactions in the protein that are 1,000 times faster than any seen in an X-ray experiment before.

    “The new data show for the first time how the bacterial sensor reacts immediately after it absorbs light,” says co-author Andy Aquila from SLAC. “The initial response, which is almost instantaneous, is absolutely crucial because it creates a ripple effect in the protein, setting the stage for its biological function.”

    The technique could prove valuable to unveil a number of other important ultrafast light-driven processes, for instance how visual pigments in the human eye respond to light, and how absorbing too much of it damages them; how photosynthetic organisms turn light into chemical energy, a process that could serve as a model for the development of new energy technologies; or how atomic structures respond to light pulses of different shape and duration, an important first step toward controlling chemical reactions with light.

    Together with the University of Wisconsin, Milwaukee, SLAC and DESY, the following institutions were involved in this study: Imperial College London, the University of Jyväskylä in Finland, Arizona State University, Max Planck Institute for Structure and Dynamics of Matter in Hamburg, State University of New York at Buffalo, University of Chicago, Lawrence Livermore National Laboratory and University of Hamburg.

    *Science paper:
    Femtosecond structural dynamics drives the trans/cis isomerization in photoactive yellow protein

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 9:05 am on May 3, 2016 Permalink | Reply
    Tags: , DESY, Polaritons   

    From DESY: “Crossing light with matter” 

    DESY
    DESY

    2016/05/02

    1
    The “plot for experts”: the recorded detector image shows that the incident X-ray radiation is amplified particularly at certain angles (blue and green areas). The energy difference between the two resonances that occur is a tiny 37.3 nano-electronvolts. No image credit.

    Precision spectroscopy of X-ray polaritons

    When light interacts with matter, it may be deflected or absorbed, resulting in the excitation of atoms and molecules; but the interaction can also produce composite states of light and matter which are neither one thing nor the other, and therefore have a name of their own – polaritons. These hybrid particles, named in allusion to the particles of light, photons, have now been prepared and accurately measured for the first time in the field of hard X-rays by researchers of DESY, ESRF in Grenoble, Helmholtz Institute in Jena and University of Jena. In the journal Nature Photonics, they describe* the surprising discoveries they made in the process.

    From a scientific point of view, polaritons are an extremely interesting type of quasiparticles. Scientists have recently succeeded in using polaritons to create a new type of source of visible laser light which does not depend on the stimulated emission that is necessary in conventional lasers. If this technology can be transferred to the field of X-rays, it could serve as the basis for a new type of narrow-band X-ray laser.

    Polaritons can be created particularly well using atoms whose nuclei have very sharply defined excitation states, so-called resonances. In the domain of X-rays, the Mössbauer isotope iron-57 (57Fe), whose atomic nucleus displays an extremely narrow energy resonance at an energy of 14.4 kilo-electronvolts (keV), is ideal for this purpose. For their experiment, the scientists manufactured periodic stacks made of alternating layers of 57Fe and non-resonant 56Fe, the most commonly occurring isotope of iron, each less than two nanometres thick. When X-rays from a synchrotron source are shone at such a periodic array of atoms at a certain angle, the layers act as an amplifier for the X-rays: resonance occurs at precisely the same energy as that displayed by the 57Fe nuclei. “This combination of two different resonant systems gives rise to a remarkable phenomenon,” explains Johann Haber, the principle author of the study and a doctoral student at DESY. “The resonances of the X-rays and the atomic nuclei seem to try and get out of each other’s way, because a hybrid of atoms and light is formed, which displays two new resonances having different energies that weren’t present beforehand.” This is a so-called collective effect which is caused by the mutual interaction of a large number of atomic nuclei with the X-rays.”

    The separation of the energy levels of these new resonances closely depends on the interaction between the nuclei and the X-rays. In their experiment, the scientists were for the first time able to determine the spectral structure of the resonances of such a system with extremely high precision. They were helped in this by a novel detection method developed by the team surrounding Ingo Uschmann, a researcher from Jena. This method is able to separate the signal of the atomic nuclei from the background signal with a very high degree of sensitivity. Thanks to this apparatus, the scientists managed to measure the two new resonances, which are separated by only 37.3 nano-electronvolts and which can be attributed to the creation of polaritons. “We were able to give an excellent theoretical description of the results using a quantum-optical model specifically developed for this purpose,” says Johann Haber.

    “Being able to prepare and measure polaritons of this type in the X-ray range is an important step on the path to the high-precision creation of radiation fields by modern X-ray sources, especially by the new X-ray lasers,” explains Ralf Röhlsberger, the researcher from DESY who was in charge of this work group. “The simultaneous emission of many identical photons during the decay of nuclear polaritons could lead to extremely narrow-band, non-classical light sources in the X-ray range, and open the way for new applications in high-precision spectroscopy.” At the same time, the experiment is a further step towards establishing quantum optics in the X-ray domain.

    *Science paper:
    Collective strong coupling of X-rays and nuclei in a nuclear optical lattice

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 11:39 am on April 18, 2016 Permalink | Reply
    Tags: , , DESY, , , XFEL   

    From LC: “From metal sheet to particle accelerator (Part 1of 3)” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    14 April 2016
    Ricarda Laasch

    1
    Cavity production at Zanon in Italy. Image: DESY, Heiner Müller-Elsner

    In September 2015, the 50th accelerator module for the X-ray free-electron laser European XFEL was tested at DESY. One hundred accelerator modules are needed for the two-kilometre-long electron accelerator of the X-ray free-electron laser. Each module consists of eight cavities, the actual accelerating structures. This is the first of a three-part series (first published in DESY inForm) about how these technological masterpieces are manufactured. Part 1 is about cavities; their production has now been completed.

    Two companies have been commissioned with the cavity production: Research Instruments (RI) in Germany and Zanon in Italy. “This is the first time we have ordered cavities virtually ready for operation from industry,” emphasises Axel Matheisen who together with Waldemar Singer leads a team of engineers and technicians at DESY supervising these firms. In the past, industry had only carried out the mechanical production steps. “For that reason, our greatest concern was whether we would manage to convey the necessary knowledge in a way that the companies are able to produce complete cavities,” says Mattheisen. The tested cavities prove that this knowledge transfer worked perfectly.

    At the beginning of the long production process, there is a square niobium sheet with an edge length of 26.5 centimetres and a thickness of 2.8 millimetres. For the construction of the accelerator, the purity of 14 700 sheets is tested at DESY before being dispatched to the two production firms. There, the sheets are deep-drawn to so-called half cells which gives them the appropriate shape for further processing. A stamp is used to obtain the required hollow pattern … the cavity.

    Subsequently, 18 half cells are welded together to form one cavity. Since niobium oxidises very easily, this cannot be done with a flame. Instead, the half cells are welded together with an electron beam in a vacuum chamber. The advantage: this procedure is very clean. For this reason, the nine-cell cavity must be protected from new contamination during further processing.

    For accelerator operation, the quality of the cavity’s inner surface is extremely important. It must not only be hyper clean but also exceptionally smooth. “In the past, the cavities were delivered to us and we did the rest. This went quite well with ten or occasionally with 30 cavities per year. But it was clear that this would not be possible with some 100 cavities per year,” Mattheisen says. For the construction of the European XFEL, the firms had to learn to carry out the surface treatment according to the “DESY recipe” and to work in a nearly dust-free cleanroom. “This was completely new for them and therefore, communication was ex- tremely important,” Mattheisen points out. The most important steps in this process are pickling, baking, tuning, dressing and rinsing.

    For pickling, various different acid mixtures are lled into the cavity. The acid reacts with the metal surface of the cavity and removes processing residues and polishes the surface. The acids’ mixture ratio and the extent of the pickling procedure have been optimised during many years of research at DESY. Baking follows pickling: the cavity is heated at 800 degrees centigrade for several hours in a humidity-free vacuum environment. During this treatment, tensions in the metal originating from shaping and welding are released and the ne crystal structures of niobium are newly arranged.

    After getting out of the oven, the cavity is tuned. In order to accelerate particles during operation, electromagnetic fields are induced to oscillate in the cavity and, eventually, the oscillation will turn into resonance. For this aim, however, the shape of each cavity cell must be exactly tuned to the accelerator frequency of 1.3 gigahertz. In the process of tuning, the resonance frequency is measured and when it diverges from the desired frequency, the cavity must be retuned. For this purpose, the cavity shells are pressed and pushed accordingly. Slight shape alterations can signi cantly improve the resonance.

    The next step is dressing: the cavity is welded into its helium tank. Liquid helium cools down the cavity in operation to minus 271 degrees centigrade to generate superconductivity and remove heat. Subsequently, a total of four antennae are to be mounted onto the cavity. One of it feeds the electromagnetic field into the cavity, the others recover it at the opposite end. “Doing this kind of mounting in a cleanroom is not the average, not even for industry,” says Mattheisen. “It is not usual work to set bolts and nuts in a cleanroom; it requires practice and, above all, patience since all procedures must be carried out slowly.”

    The production is completed with rinsing: the inner surface of the cavity is sprayed off for some hours with high pressure ultrapure water of 100 bar. Now, the cavity with a vacuum inside leaves the cleanroom. Packed in a special case, it is shipped to DESY by lorry. However, the cavity is not yet ready for installation into a European XFEL module. It will first have to demonstrate its qualities.

    See the full article here .

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    The Linear Collider Collaboration is an organisation that brings the two most likely candidates, the Compact Linear Collider Study (CLIC) and the International Liner Collider (ILC), together under one roof. Headed by former LHC Project Manager Lyn Evans, it strives to coordinate the research and development work that is being done for accelerators and detectors around the world and to take the project linear collider to the next step: a decision that it will be built, and where.

    Some 2000 scientists – particle physicists, accelerator physicists, engineers – are involved in the ILC or in CLIC, and often in both projects. They work on state-of-the-art detector technologies, new acceleration techniques, the civil engineering aspect of building a straight tunnel of at least 30 kilometres in length, a reliable cost estimate and many more aspects that projects of this scale require. The Linear Collider Collaboration ensures that synergies between the two friendly competitors are used to the maximum.

    Linear Collider Colaboration Banner

     
  • richardmitnick 8:31 pm on March 16, 2016 Permalink | Reply
    Tags: , , DESY,   

    From DESY: “Researchers locate particle accelerator of unprecedented energy in the centre of our galaxy” 

    DESY
    DESY

    2016/03/16
    No writer credit found

    Scientists of the H.E.S.S. Observatory have identified an area around the black hole in the centre of the Milky Way that emits intense gamma radiation of extremely high energy. The source of the radiation is an astrophysical accelerator speeding up protons to energies of up to one peta electronvolts (PeV) – more than 100 times higher than the largest and most powerful man-made particle accelerator, the Large Hadron Collider LHC at CERN. The scientists have now published their detailed analysis of recent H.E.S.S. data in the scientific journal Nature. The analysis shows the first identification of a source of cosmic rays with peta-electronvolt energy within the Milky Way: it is very likely the supermassive black hole [Sag A*] at the centre of our galaxy itself.

    Sag A prime
    SAG A*

    For more than 10 years, H.E.S.S. (High Energy Stereoscopic System), a gamma ray telescope in Namibia which is operated by 150 scientists from 12 countries, has mapped the centre of the Milky Way in highest energy gamma rays.

    HESS Cherenko Array
    H.E.S.S. Array

    The gamma rays observed by the researchers are produced by so-called cosmic radiation – high-energy protons, electrons and atomic nuclei, which are accelerated in different places of the universe. Scientists have wondered about the astrophysical sources of this cosmic radiation since its discovery more than a century ago. The problem is that the particles are electrically charged and are therefore deflected in interstellar magnetic fields from their straight path. For this reason, their flight does not point back to its place of production. However, the particles of cosmic radiation often encounter interstellar gas or photons close to their source, producing high-energy gamma rays which reach the earth on a straight path. These gamma rays are used by the scientists of H.E.S.S. Observatory to make the sources of cosmic rays in the sky visible.

    When gamma rays hit the Earth´s atmosphere, they produce short bluish flashes of light that can be detected by large mirror telescopes with fast light sensors at night. With this technique, more than 100 sources of high-energy gamma rays have been discovered in the sky over the past decades. Currently, H.E.S.S. is the most sensitive tool for their detection.

    It is known that cosmic radiation with energies up to about 100 tera electronvolts (TeV) is generated in the Milky Way. However theoretical arguments and the direct measurement of the cosmic radiation suggest that these particles should be accelerated in our galaxy up to energies of at least one peta electronvolt (PeV). In recent years, many extragalactic sources have been discovered that accelerate cosmic rays to multi-TeV energies, but the search for accelerators of the highest-energy cosmic rays in our galaxy remains unsuccessful so far.

    Detailed observations of the centre of the Milky Way, which were carried out with the H.E.S.S. telescopes during the past 10 years, now provide the first answers. “We have located an astrophysical accelerator accelerating protons to energies of up to one peta electronvolts, and that continuously over at least 1000 years,” says Prof. Christian Stegmann, head of DESY in Zeuthen and former spokesperson of the H.E.S.S. Collaboration.

    Already during the first years of observation since 2002 H.E.S.S. had detected a strong compact source and an extended band of diffuse highest-energy gamma rays in the galactic centre. Evidence of this diffuse radiation, which covers an area of about 500 light years across, was already a clear indication of a source of cosmic rays in this region; proof of the source itself remained unfulfilled for the researchers. A significantly larger amount of observational data together with advances in analytical techniques have made it now possible to measure for the first time both the spatial distribution as well as the energy of the cosmic rays.

    Although the central region of our Milky Way hosts many objects that can generate high-energy cosmic rays, for instance a supernova remnant, a pulsar wind nebulae and a compact star clusters, the measurement of gamma rays from the galactic centre provides strong evidence that the supermassive black hole at the galactic centre itself accelerates protons to an energy of up to one PeV.

    Supernova remnant Crab nebula
    Crab supernova remnant

    “Our data show that the observed glow of gamma rays around the galactic centre is symmetrical,” says H.E.S.S. researcher Stefan Klepser from Zeuthen. “The gamma rays are of a high energy and concentrated towards the centre, which suggests that they must be the echo of a huge particle accelerator which is located in the centre of this glow.” Prof. Stegmann adds that “several possible acceleration regions can be considered, either in the immediate vicinity of the black hole, or further away, where a fraction of the material falling into the black hole is ejected back into the environment, potentially initiating the acceleration of particles.“

    However, the analysis of the measurements also shows that this source alone cannot account for the total flux of cosmic rays detected on Earth. “If, however, our central black hole has been more active in the past”, the researchers argue, “then it might actually be responsible for the entire bulk of today´s galactic cosmic rays”. If their assumption is correct, the 100-year-old mystery of the origin of cosmic rays would be solved.

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 1:01 pm on March 2, 2016 Permalink | Reply
    Tags: , DESY, ,   

    From XFEL: “All segments of first light-generating system installed in European XFEL” 

    XFEL bloc

    European XFEL

    01 March 2016
    No writer credit

    Facility reaches prominent milestone

    In the metropolitan area of Hamburg, the installation of the 35 segments of the first of three X-ray light producing components of the European XFEL has been completed. Set into one of the facility’s tunnels, the segments are the core part of three systems called undulators, which are each up to 210 metres long and will produce X-ray laser light exceeding the intensity of conventional X-ray sources by a billion times.

    XFEL Undulator
    XFEL undulator. No image credit.

    These pulses of X-ray radiation are the basis for new revolutionary experimental techniques that will allow scientists to study the nanocosmos, with applications in many fields including biochemistry, astrophysics, and materials science. The undulator installation is a major step towards the completion of the European XFEL, a 3.4 km-long X-ray free-electron laser facility that will be the world’s brightest X-ray source when completed. It is also one of Europe’s largest research projects and is due to open to users for research in 2017.

    “With the 35 segments of the first undulator beam line in place, we have clearly reached a very important milestone in the construction of our facility”, says European XFEL Managing Director Prof. Massimo Altarelli. “The X-ray flashes produced in these systems are the basis for the future research at the European XFEL. We are looking forward to 2017, when they will be used to investigate the smallest details of the structure and function of matter in the molecular world.”

    Each of the 35 segments is 5 m long, weighs 7.5 t, and is composed of two girders facing one another, each holding a line of alternating strong permanent magnets. When accelerated electrons pass through the field of alternating polarity generated by the magnets, ultrashort flashes of X-ray laser light are produced. Components between adjacent segments help ensure a consistent magnetic field between them, and control systems allow mechanical movement of components within the undulator, which allows generation of a large spectrum of photon wavelengths.

    Design, development, and prototyping work started approximately eight years ago in a joint collaboration with DESY, European XFEL’s largest shareholder. The same technology is also used in a number of projects at DESY, including the X-ray free-electron laser FLASH and the PETRA III storage ring light source.

    DESY FLASH
    DESY FLASH

    DESY Petra III interior
    DESY PETRA III

    The undulator system was built through a multinational collaboration. The challenging production involved DESY and Russian, German, Swiss, Italian, Slovenian, Swedish, and Chinese institutes and companies under the leadership of the undulator group of the European XFEL. This includes a number in-kind contributions such as electromagnets for the electron beamline designed and manufactured at several institutes in Russia and tested in Sweden; temperature monitoring units from the Manne Siegbahn Laboratory in Sweden; and movers, phase shifters, and control systems designed and manufactured by the research centre CIEMAT in Spain.

    “This was a true synergetic collaboration”, says Joachim Pflüger, group leader of the European XFEL undulator group. “The resources and experience of DESY were essential for the development of the undulator systems. Now there is a great mutual benefit!”

    This first completed undulator will generate short-wavelength “hard” X-rays that will be used for experiments with a focus on structural biology and ultrafast chemistry. All three of the undulators planned for the starting phase of the European XFEL will be operational by the end of 2016.

    How the XFEL undulator works
    How the undulator works.

    See the full article here .

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    XFEL Campus

    The Hamburg area will soon boast a research facility of superlatives: The European XFEL will generate ultrashort X-ray flashes—27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources.

    The outstanding characteristics of the facility are unique worldwide. Starting in 2017, it will open up completely new research opportunities for scientists and industrial users.

     
  • richardmitnick 2:07 pm on February 10, 2016 Permalink | Reply
    Tags: , Biomolecules, , DESY, ,   

    From DESY: “New method opens crystal clear views of biomolecules” 

    DESY
    DESY

    2016/02/11
    No writer credit found

    A scientific breakthrough gives researchers access to the blueprint of thousands of molecules of great relevance to medicine and biology. The novel technique, pioneered by a team led by DESY scientist Professor Henry Chapman from the Center for Free-Electron Laser Science CFEL and reported this week in the scientific journal Nature, opens up an easy way to determine the spatial structures of proteins and other molecules, many of which are practically inaccessible by existing methods. The structures of biomolecules reveal their modes of action and give insights into the workings of the machinery of life. Obtaining the molecular structure of particular proteins, for example, can provide the basis for the development of tailor-made drugs against many diseases. “Our discovery will allow us to directly view large protein complexes in atomic detail,” says Chapman, who is also a professor at the University of Hamburg and a member of the Hamburg Centre for Ultrafast Imaging CUI.

    Dimer crystals Detec of complex biomolecules like that of the photosystem II molecule shown here
    Slightly disordered crystals of complex biomolecules like that of the photosystem II molecule shown here produce a complex continous diffraction pattern (right, the disorder is greatly exaggerated) under X-ray light that contains far more information than the so-called Bragg peaks of a strongly ordered crystal alone (left). Credit: DESY, Eberhard Reimann

    To determine the spatial structure of a biomolecule, scientists mainly rely on a technique called crystallography. The new work offers a direct route to “read” the atomic structure of complex biomolecules by crystallography without the usual need for prior knowledge and chemical insight. “This discovery has the potential to become a true revolution for the crystallography of complex matter,” says the chairman of DESY’s board of directors, Professor Helmut Dosch.

    In crystallography, the structure of a crystal and of its constituents can be investigated by shining X-rays on it. The X-rays scatter from the crystal in many different directions, producing an intricate and characteristic pattern of numerous bright spots, called Bragg peaks (named after the British crystallography pioneers William Henry and William Lawrence Bragg). The positions and strengths of these spots contain information about the structure of the crystal and of its constituents. Using this approach, researchers have already determined the atomic structures of tens of thousands of proteins and other biomolecules.

    But the method suffers from two significant barriers, which make structure determination extremely difficult or sometimes impossible. The first is that the molecules must be formed into very high quality crystals. Most biomolecules do not naturally form crystals. However, without the necessary perfect, regular arrangement of the molecules in the crystal, only a limited number of Bragg peaks are visible. This means the structure cannot be determined, or at best only a fuzzy “low resolution” facsimile of the molecule can be found. This barrier is most severe for large protein complexes such as membrane proteins. These systems participate in a range of biological processes and many are the targets of today’s drugs. Great skill and quite some luck are needed to obtain high-quality crystals of them.

    Extreme Sudoku in three dimensions

    The second barrier is that the structure of a complex molecule is still extremely difficult to determine, even when good diffraction is available. “This task is like extreme Sudoku in three dimensions and a million boxes, but with only half the necessary clues,” explains Chapman. In crystallography, this puzzle is referred to as the phase problem. Without knowing the phase – the lag of the crests of one diffracted wave to another – it is not possible to compute an image of the molecule from the measured diffraction pattern. But phases can’t be measured. To solve the tricky phase puzzle, more information must be known than just the measured Bragg peaks. This additional information can sometimes be obtained by X-raying crystals of chemically modified molecules, or by already knowing the structure of a closely-related molecule.

    When thinking about why protein crystals do not always “diffract”, Chapman realised that imperfect crystals and the phase problem are linked. The key lies in a weak “continuous” scattering that arises when crystals become disordered. Usually, this non-Bragg, continuous diffraction is thought of as a nuisance, although it can be useful for providing insights into vibrations and dynamics of molecules. But when the disorder consists only of displacements of the individual molecules from their ideal positions in the crystal then the “background” takes on a much more complex character – and its rich structure is anything but diffuse. It then offers a much bigger prize than the analysis of the Bragg peaks: the continuously-modulated “background” fully encodes the diffracted waves from individual “single” molecules.

    “If you would shoot X-rays on a single molecule, it would produce a continuous diffraction pattern free of any Bragg spots,” explains lead author Dr. Kartik Ayyer from Chapman’s CFEL group at DESY. “The pattern would be extremely weak, however, and very difficult to measure. But the ‘background’ in our crystal analysis is like accumulating many shots from individually-aligned single molecules. We essentially just use the crystal as a way to get a lot of single molecules, aligned in common orientations, into the beam.” With imperfect, disordered crystals, the continuous diffraction fills in the gaps and beyond the Bragg peaks, giving vastly more information than in normal crystallography. With this additional gain in information, the phase problem can be uniquely solved without having to resort to other measurements or assumptions. In the analogy of the Sudoku puzzle, the measurements provide enough clues to always arrive at the right answer.

    The best crystals are imperfect crystals

    This novel concept leads to a paradigm shift in crystallography — the most ordered crystals are 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 single molecule diffraction – we have never had this in crystallography before,” he explains. “But we have long known how to solve single-molecule diffraction if we could measure it.” The field of coherent diffractive imaging, spurred by the availability of laser-like beams from X-ray free-electron lasers, has developed powerful algorithms to directly solve the phase problem in this case, without having to know anything at all about the molecule. “You don’t even have to know chemistry,” says Chapman, “but you can learn it by looking at the three-dimensional image you get.”

    To demonstrate their novel analysis method, the Chapman group teamed up with the group of Professor Petra Fromme from the Arizona State University (ASU), and other colleagues from ASU, University of Wisconsin, the Greek Foundation for Research and Technology – Hellas FORTH, and SLAC National Accelerator Laboratory in the U.S. They used the world’s most powerful X-ray laser LCLS at SLAC to X-ray imperfect microcrystals of a membrane protein complex called Photosystem II that is part of the photosynthesis machinery in plants.

    SLAC LCLS Inside
    Inside LCLS

    Including the continuous diffraction pattern into the analysis immediately improved the spatial resolution around a quarter from 4.5 Ångström to 3.5 Ångström (an Ångström is 0.1 nanometres). The obtained image gave fine definition of molecular features that usually require fitting a chemical model to see. “That is a pretty big deal for biomolecules,” explains co-author Dr. Anton Barty from DESY. “And we can further improve the resolution if we take more patterns.” The team had only a few hours of measuring time for these experiments, while full-scale measuring campaigns usually last a couple of days.

    The scientists hope to obtain even clearer and higher resolution images of photosystem II and many other macromolecules with their new technique. “This kind of continuous diffraction has actually been seen for a long time from many different poorly-diffracting crystals,” says Chapman. “It wasn’t understood that you can get structural information from it and so analysis techniques suppressed it. We’re going to be busy to see if we can solve structures of molecules from old discarded data.”

    Reference:
    Macromolecular diffractive imaging using imperfect crystals; Kartik Ayyer et al.; Nature (2016); DOI: 10.1038/nature16949

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
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