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  • richardmitnick 7:50 am on April 15, 2015 Permalink | Reply
    Tags: , DESY,   

    From DESY: “Discovery of a new device concept based on electronic self-organization” 

    DESY
    DESY

    April 15, 2015
    No Writer Credit

    1
    Orbital texture within an atomic layer of 1T-TaS2, as obtained by state-of-the-art density functional theory. (Credit: Authors)

    An international team of scientists from IFW Dresden, TU-Dresden, EPFL Lausanne (Switzerland), University of Illinois (US) and DESY found that the reordering of orbitals can cause a semiconductor to metal transition in nanostructures made of transition metal dichalcogenides. These orbital effects also provide an explanation for the recently discovered photoinduced semiconductor to metal transition in the transition metal dichalcogenide 1T-TaS2, indicating that these transitions can be triggered on ultrafast timescales.

    The results have been obtained by combining X-ray diffraction at DESY’s light source DORIS III with photoemission done at BESSY in Berlin, and band structure calculations performed at the IFW in Dresden. The authors present their findings in the journal “Nature Physics”.

    DESY DORIS III
    DORIS III

    BESSY II Synchrotron II
    BESSY II

    The transition metal dichalcogenides realize layered crystal structures, which make it easy to prepare them in thin-film form –an extremely advantageous feature for nanotechnology. This layered structure also causes a strongly anisotropic, quasi two-dimensional electronic structure. The latter in turn strongly favors electronic ordering instabilities and, in fact, the transition metal dichalcogenides are well known to exhibit an instability against the formation of so-called charge density waves (CDW), i.e, a crystallization of mobile electrons in the two-dimensional layers.

    Correspondingly, most of the previous research focused essentially isolated two-dimensional layers. However, drastic changes of the X-ray diffraction pattern of the CDW measured at the DORIS III beamline BW5, revealed that this may not be sufficient and that correlations between layers need also to be considered. Indeed the electronic structure calculations uncovered complex orbital textures (see figure), which are interwoven with the CDW order and cause dramatic differences in the electronic structure depending on the alignment of the orbitals between neighboring planes.

    2
    The switching between metastable orbital orders corresponding to the semiconducting (top) and metallic state (bottom). (Copyright: Nature Physics)

    The new twist of the paper is the discovery that these orbital-mediated interactions may enable to drive semiconductor to metal transitions with technologically pertinent gaps and on ultrafast timescales. This opens up new routes to fabricate optically switchable devices based on orbitally textured CDW compounds, a new technology that could be called “Orbitronics”.

    These discoveries are hence of special relevance for the ongoing development of novel, miniaturized and ultrafast devices for electronic and sensing applications. They also enable to explain a number of long-standing puzzles associated with the electronic self-organization in 1T-TaS2: the ultrafast response to optical excitations, the high sensitivity to pressure and a mysterious commensurate phase that is commonly thought to be a special phase (‘Mott phase’) and that is not found in any other isostructural modification.

    Charge density wave states have recently also been observed in a large number of cuprate high-Tc superconductors and their relation to other phases like the pseudo gap, the anti-ferro magnetic phase and superconductivity is currently under debate. To elucidate the role played by the orbital degree of freedom for superconductivity will be another challenge.

    (from authors)

    Publication:

    „Orbital textures and charge density waves in transition metal dichalcogenides“, T. Ritschel, J. Trinckauf, K. Koepernik, B. Büchner, M. v. Zimmermann, H. Berger, Y. I. Joe, P. Abbamonte and J. Geck, Nature Physics (2015), DOI: 10.1038/nphys3267

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 9:09 am on April 10, 2015 Permalink | Reply
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    From DESY: “Gamma-ray bursts as cosmic particle accelerators” 

    DESY
    DESY

    2015/04/10
    No Writer Credit

    1

    Study provides new insights into the universe’s most powerful explosions

    A new study provides detailed insight into the most powerful explosions in the universe: gamma-ray bursts. The simulation explains the modes of particle acceleration in these rare events better than previous models and can explain conflicting astrophysical observations. Scientists from DESY and two US universites present their work in the journal Nature Communications.

    Gamma-ray bursts happen when extremely massive stars go supernova. These explosions can be seen nearly across the whole visible universe, up to several billion lightyears. The giant stars’ strong magnetic fields channel most of the explosion’s energy into two powerful jets of electrically charged gas (plasma), one at each magnetic pole. These plasma jets are powerful natural particle accelerators.

    Scientists expect the plasma jets to be a significant source of cosmic rays, high-energy subatomic particles (mostly protons) that constantly pepper Earth’s atmosphere from space. These particles can have up to ten million times the energy of the protons in the Large Hadron Collider (LHC), currently the most powerful particle accelerator on Earth at the European particle physics laboratory CERN.

    But if gamma-ray bursts are a significant source of cosmic rays, scientists expect them for physics reasons to also shed a large number of light elementary particles called neutrinos. The IceCube observatory at the South Pole, in which DESY is the main European partner, is looking for exactly those high-energy cosmic neutrinos.

    ICECUBE neutrino detector
    IceCube neutrino detector interior
    IceCube

    However, none have been detected so far from gamma-ray bursts. This means that at least ten times fewer neutrinos reach us from gamma-ray bursts than were expected. “This throws up new questions for theory,” says DESY scientist Walter Winter, a co-author of the new study. “Perhaps, our concept of gamma-ray bursts was too simple.”

    2
    The plasma is ejected in shells at different speeds. When the shells collide, particles are accelerated. Illustration: Mauricio Bustamante/DESY

    3
    Neutrinos are mainly generated at lower distance from the source, cosmic rays at medium distance and gamma-rays at greater distance. Illustration Mauricio Bustamante/DESY

    Existing models of these powerful explosions assumed that cosmic rays, neutrinos and gamma-rays all come from the same region within the plasma jets. The team of theoretical astroparticle physicists, including Winter from DESY, Mauricio Bustamante from Ohio State University and Philipp Baerwald and Kohta Murase from Pennsylvania State University, has now developed a more dynamic model of gamma-ray bursts. According to this model, the plasma is ejected in the form of shells at different speed. In considerable distance from the source, these shells collide, thereby accelerating particles.

    This approach can not only explain the observed strong variations in the light curves of gamma-ray bursts. A consequence of this model is also that neutrinos, cosmic rays and gamma-rays must be produced in completely different regions of the jets. This can explain, why the expected flux of neutrinos could not be found. “We expect that the next generation of neutrino telescopes, such as IceCube-Gen-2, will be sensitive to this minimal flux that we’re predicting”, says Bustamante. In contrast to earlier models, this estimate is more robust and does only weakly depend on the characteristics of individual gamma-ray bursts.

    Reference:
    Neutrino and Csomic-Ray Emission from Multiple Internal Shocks In Gamma-Ray Bursts; Mauricio Bustamante, Philipp Baerwald, Kohta Murase & Walter Winter; „Nature Communications“, 2015; DOI: 10.1038/ncomms7783

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 8:30 am on March 27, 2015 Permalink | Reply
    Tags: , , , DESY,   

    From DESY: “Negotiations for CTA northern site to start” 

    DESY
    DESY

    2015/03/26
    No Writer Credit

    Cherenkov Telescope Array
    Proposed Cherenkov Telescope Array for hunting Gamma Rays

    On 26 March 2015, the partner countries of Cherenkov Telescope Array (CTA) have decided to start negotiations for the location of the telescope array in the northern hemisphere. At a meeting in Heidelberg representatives of ministries and funding agencies have decided to begin negotiations with Spain for a possible location on La Palma and Mexico for one in San Pedro Mártir. Another candidate site in Arizona (USA) is considered as a possible back-up site.

    “I appreciate that we have successfully chosen the northern candidate sites with whom we would like to start negotiations as soon as possible,” said Beatrix Vierkorn-Rudolph from the German Federal Ministry of Research and Education, chair of the CTA Resource Board, after the decision of the voting members representing Argentina, Austria, Brazil, Czech Republic, France, Germany, Italy, Japan, Poland, South Africa, Spain, Switzerland and the UK. After negotiations, the Board will select the final site in November 2015. In regards to the southern hemisphere site, negotiations with the candidates Namibia and Chile are progressing and are expected to end in August 2015. Christian Stegmann from DESY added: “I’m very much looking forward to the final site decisions later this year; scientists worldwide are eager to see CTA advancing towards implementation.”

    Currently in its pre-construction phase, determining the northern and southern hemisphere sites will be a critical step towards the realization of the Cherenkov Telescope Array. “I’m looking forward to converging on final designs for the telescope arrays now that negotiations will start with specific locations in mind,” said Christopher Townsley, CTA project manager. Following the site selection, the project will move forward with construction of the first telescopes on site planned for 2016.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 3:35 pm on March 25, 2015 Permalink | Reply
    Tags: , DESY, ,   

    From DESY: “Latest result from neutrino observatory IceCube opens up new possibilities for particle physics” 

    DESY
    DESY

    2015/03/24
    No Writer Credit

    South Pole detector measures neutrino oscillations with high precision

    The South Pole observatory IceCube has recorded evidence that elusive elementary particles called neutrinos changing their identity as they travel through the Earth and its atmosphere.

    1
    The IceCube laboratory at the Scott Amundsen South Pole station hosts the computers collecting the detector data (picture: Felipe Pedreros. IceCube/NSF)

    IceCube neutrino detector interior
    IceCube Neutrino Experiment interior

    The observation of these neutrino oscillations, first announced in 1998 by the Super Kamiokande experiment in Japan, opens up new possibilities for particle physics with the Antarctic telescope that was originally designed to detect neutrinos from faraway sources in the cosmos.

    Super-Kamiokande experiment Japan
    Super Kamiokande experiment

    “We are very pleased that the IceCube detector with its DeepCore array can be used to observe neutrino oscillations with high precision,” says Olga Botner, Spokesperson of the IceCube experiment. “DeepCore was designed on the initiative of Per Olof Hulth who sadly passed away recently, to significantly lower IceCube’s energy threshold. The results show that IceCube can contribute to nailing down the oscillation parameters and motivate us to pursue our plans for an IceCube upgrade called PINGU to measure neutrino properties.”

    IceCube DeepCore
    IceCube DeepCore

    IceCube PINGU
    IceCube PINGU

    “IceCube records over one hundred thousand atmospheric neutrinos every year, most of them muon neutrinos produced by the interaction of fast cosmic particles with the atmosphere,” says Rolf Nahnhauer, leading scientist at DESY. The subdetector DeepCore allows for detecting neutrinos with energies down to 10 giga-electronvolts (GeV). “According to our understanding of neutrino oscillations, IceCube should see fewer muon neutrinos at energies around 25 GeV that reach IceCube after crossing the entire Earth,” explains Rolf Nahnhauer. “The reason for these missing muon neutrinos is that they oscillate into other types.” IceCube researchers selected Northern Hemisphere muon neutrino candidates with energies between a few GeV and around 50 GeV from data taken between May 2011 and April 2014. About 5200 events were found, much below the 7000 expected in the non-oscillations scenario.

    Neutrinos remain the most mysterious of the known elementary particles. Postulated by Austrian physicist Wolfgang Pauli in 1930, it took 25 years for their experimental detection. “Neutrinos are elusive,” says Olga Botner, ” and can travel through an enormous amount of material, even the whole Earth, without interacting.” Nevertheless, physicists have built more and more sophisticated instruments to reveal the mysteries of this very light particles. One of the surprising results was that the three different types of neutrinos, electron, muon and tau neutrinos, can change their identity, transforming from one type of neutrino to another. This phenomenon is known as neutrino oscillation. “Neutrino oscillations are only possible if neutrinos have a mass,” explains Nahnhauer. “On the other hand, massive neutrinos are not explained within the otherwise so successful Standard Model of particle physics.”

    3
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    The strength of the oscillation and the distances over which it develops depend on two parameters: the so-called mixing angle and the mass difference. The values of these parameters have been constrained by precise measurements of neutrinos from the sun, the atmosphere, nuclear reactors, and particle accelerators.

    The IceCube neutrino observatory at the South Pole has already demonstrated that it is a powerful tool to explore the universe by neutrinos, using the Antarctic ice sheet as its detection material. An array of more than 5000 optical sensors distributed in a cubic kilometer of the ice records the very rare collisions of neutrinos. And less than two years ago, IceCube physicists announced the discovery of the first high-energy neutrinos from the cosmos, acknowledged as “breakthrough of the year” by the journal Physics World.

    Now IceCube has proven that it can also deliver top particle physics results. The new measurement by the IceCube collaboration resulting in significantly improved constraints on the neutrino oscillation parameters has been accepted for publication by the scientific journal Physical Review D.

    Three years of IceCube data yielded a similar precision to that reached from about 15 years of Super-Kamiokande data. In contrast to the purified water in Super-Kamiokande’s 50-kiloton vessel, IceCube uses a natural target material, the glacier ice at the South Pole. IceCube’s 500 times larger observation volume produces larger event statistics in shorter times. “Both Super-Kamiokande and IceCube use the same ‘beam‘ which is atmospheric neutrinos, but at different energies. And we reach similar precision of the measurable oscillation parameters,” says Juan Pablo Yanez, postdoctoral researcher at DESY, who is the corresponding author of the paper. “The results now derived from IceCube data show errors still larger than, but already comparable to the most precise neutrino beam experiments MINOS and T2K. But as IceCube keeps taking data and improving the analyses we are hopeful to catch up soon.” adds Yanez.

    Currently the scientists are planning an upgrade of the IceCube detector called PINGU (Precision IceCube Next Generation Upgrade). A much higher density of optical modules in the whole central region will improve the sensitivity to several fundamental questions associated with neutrinos.

    “In particular we want to measure the so called neutrino mass hierarchy – whether there are two heavier neutrinos and one light one, or whether it is the other way around.” explains Rolf Nahnhauer. “This is important to understand how neutrinos obtain masses, but also has significant relevance on how the cosmos evolves. The current results provide an important experimental confirmation that our concepts work.“

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 9:20 am on March 13, 2015 Permalink | Reply
    Tags: , DESY, ,   

    From DESY: “Molecules perform endless cartwheels” 

    DESY
    DESY

    2015/03/13
    No Writer Credit

    1
    An near-infrared laser (red) makes the originally disordered molecules perform synchronized cartwheels so that all the molecules at a particular position along the beam are oriented in the same direction. Picture: Jens S. Kienitz/CFEL, DESY and CUI

    Scientists in Hamburg have resorted to a physical trick to persuade entire groups of molecules to perform synchronized cartwheels, virtually endlessly. This technique opens up new opportunities for imaging molecules and their chemical dynamics. Prof. Jochen Küpper and his team at the Center for Free-Electron Laser Science (CFEL) are presenting their findings in the journal Physical Review Letters.

    2
    The FLASH experimental hall with beamlines which guide the laser-like light of the free-electron laser FLASH to the experimental stations. (Source: DESY)

    Intense flashes of x-rays emitted by so-called free electron lasers offer detailed insights into the world of molecules. Researchers use them, for example, to explore the atomic structure of biomolecules and to better understand their function, or they try to film dynamic processes taking place in the nanocosm – such as the excitation cycle in photosynthesis. Until now, however, such molecules have generally had to be available in a crystalline form for such examinations to be carried out, because the individual molecules alone do not produce a strong enough signal. In a crystal, the molecules are arranged in regular patterns so that the signals from each add up, allowing an analysis on an atomic level.

    “Crystals represent a very special state, however – often imposed and unnatural”, explains Sebastian Trippel, the first author of the paper. Scientists would therefore often prefer to examine free molecules directly. But how can such free molecules be moved, in a controlled fashion, into the x-ray beam of a free electron laser? Scientists have been experimenting with different methods of guiding the molecules, using electromagnetic fields and laser light, and aligning them in a particular direction at the same time.

    They have already succeeded in strongly orienting entire ensembles of molecules in the same direction for such examinations, “however when you do this, the molecular ballet is influenced by an electromagnetic field, which can in turn have an unwanted effect on the measurements,” explains Jochen Küpper, a scientist at DESY, who is also a member of the Hamburger Center for Ultrafast Imaging (CUI) and a professor at the University of Hamburg. The molecular tamers working with Küpper have now found a way of preserving the alignment of molecular ensembles even after the laser field has been switched off.

    For their test, the researchers used carbonyl sulfide (OCS) as a simple model system. The three atoms that make up this molecule (carbon, oxygen and sulfur) lie in a straight line, and this simple structure makes it particularly suitable for demonstrating the method. The scientists released high-pressure carbonyl sulfide molecules into a vacuum chamber through a fine nozzle, as a result of which the gas expanded and thereby cooled down rapidly. They then used a so-called deflector, a kind of prism for molecules, to fish out those molecules that were in the lowest-energy state.

    A tailored pulse of infrared laser light mixed this state with the first excited quantum state. As a result, the molecules started to perform, synchronously, a so-called inversion, whereby the individual molecules fell in step with each other, so that the sulphur atom (S) of the molecules all simultaneously pointed up or down. This inversion continued undiminished even after the molecules had passed the infrared laser and were moving through space without being affected by an alternating electromagnetic field. “In a sense, the laser forces the molecules to perform synchronous cartwheels, which would continue forever if they didn’t eventually reach the walls of the experimental apparatus”, Trippel explains.

    The molecules travel an almost infinite distance compared with the period of their inversion – they have enough time to perform hundreds of thousands of cycles of this motion before they collide with the wall of the vacuum chamber. For experimenters, this offers some very tangible advantages: all they have to do in order to select a specific orientation of the molecular ensemble under scrutiny – in which the two orientations alternate regularly – is to select the appropriate moment in time behind the laser beam.

    This method not only works for the two lowest energy states, but in principle for all states of a linear molecule, as the researchers point out in their paper. “This targeted molecular choreography opens up new possibilities for holding ensembles of free molecules in the x-ray beam of a free electron laser in a controlled fashion, so that they can be investigated there,” says Küpper.

    Reference:
    Two-state wave packet for strong field-free molecular orientation; Sebastian Trippel, Terry Mullins, Nele L. M. Müller, Jens S. Kienitz, Rosario González-Férez and Jochen Küpper; Physical Review Letters, 2015; DOI: 10.1103/PhysRevLett.114.103003

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 3:32 pm on February 11, 2015 Permalink | Reply
    Tags: , DESY, X-ray Lasers,   

    From DESY: “Taking high-speed snapshots of living cells with an X-ray laser” 

    DESY
    DESY

    2015/02/11

    X-ray imaging method captures living cells with unprecedented speed and resolution

    An international team led by Uppsala University and including scientists from DESY and the European XFEL has for the first time successfully imaged whole living bacterial cells with an X-ray laser. The method used in this experiment can produce results that are of higher spatial and temporal resolution than even the best optical microscopy techniques, with the added possibility of creating detailed 3D models of the cells. “When you really want to understand the details of a cell’s functions, you need it alive”, says Uppsala University Professor Janos Hajdu, one of the lead researchers in the experiment and an advisor to European XFEL. The technique, as described in the journal Nature Communications, allows scientists a clearer view into the complicated world of the cell.

    1
    Reconstructed electron density of a cyanobacterium. Credit: Gjis van der Schot/Universität Uppsala

    The method involves spraying the cells into a fine aerosol ahead of the pulses of an X-ray laser. This aerosol — literally a beam of living cells — has a thickness less than that of a human hair. The ultra-short X-ray pulses scatter from the individual cells and the resulting diffraction patterns are picked up by a detector. Computer programs, including several developed in collaboration between Uppsala and DESY, analyze the data and reconstruct the image of the cells.

    “While the X-rays destroy the cells in the process, an X-ray laser’s ultra-short flashes and high intensity allow the diffraction data to be captured quickly enough to get an accurate picture of the sample before it disintegrates. The flashes outrun the damage,” says Anton Barty, a DESY scientist at the Center for Free Electron Laser Science who is also a co-author of this paper.

    This technique, called “diffraction-before-destruction”, has been proven to work in several studies with biological and also with inorganic samples before. The cell imaging experiment took place at the LCLS X-ray laser at SLAC National Accelerator Laboratory in Menlo Park, California. Two types of cyanobacteria were used in the study called Cyanobium gracile and Synechococcus elongatus. These cells have a roughly cylindrical shape that is immediately apparent in the reconstructions from the diffraction data.

    2
    Nomarski image of the same cyanobacterium, calculated from the recontruction. Credit: Gjis van der Schot/Universität Uppsala

    However, the leader of the experiment, Tomas Ekeberg, an assistant professor in molecular biophysics at Uppsala University, acknowledged that the pictures could have been even better but the data were more than the detectors could handle.

    “We so far can only accurately reconstruct to 76 nanometres resolution, but the data we collected indicates that we can get down to 4 nanometres, which is the size of a protein molecule”, Ekeberg says. A nanometre is a billion times smaller than a metre. The reason for the drop in resolution was what amounted to an overexposure, just like too bright of a light in a photograph. “This experiment was a proof-of-concept study”, says Ekeberg. “We will be able to obtain much higher-resolution pictures when we can use a filter to help reduce the overexposure.” adds Gijs van der Schot, a Ph.D. student with Ekeberg and the first author on the paper.

    Acquiring high-resolution micrographs from cells in conventional experiments has usually meant long exposure times and about a million times higher radiation doses than the dose that kills a living cell. As a consequence, much of what we know today about cells at high-resolution comes from dead material. The team’s new method can access the structure of living cells at practically instantaneous speeds, before radiation damage has time to set in. Each image is formed in femtoseconds. A femtosecond is a millionth of a billionth of a second. Such a revolutionary tool could help scientists better understand some of the mysteries of cellular function and behaviour. Additionally, this technique opens the door for future 3D modelling of cells and cellular activities, and provides key insights to fundamental processes in several important areas of disease research.

    3
    X-ray diffraction pattern produced by a cyanobacterium at the LCLS. Credit: Gjis van der Schot/Universität Uppsala

    “This is a promising method for the European XFEL”, says Joachim Schulz, a scientist at European XFEL and one of the co-authors on the paper. “It could further expand the application of bio-imaging methods to users, opening possibilities to image living organisms.”

    The team plans to fine-tune the imaging method with further experiments and work on consistently developing images at higher resolution. Additionally, Ekeberg and van der Schot predict that future studies would attempt to develop the 3D cell division models or target particular structural information about the cells for bioinformatics.

    “The contrast is tremendous between images produced using this technique and those from traditional optical microscopy of living cells”, says Hajdu. “Few believed this was possible.”

    The future for imaging is getting even brighter in Hamburg, as the European X-FEL will soon start generating ultra-short, ultra-intense X-ray pulses at 300 times higher repetition rate than the best X-ray lasers today.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 2:09 pm on February 6, 2015 Permalink | Reply
    Tags: , CREMLIN, DESY   

    From DESY: “EU project CREMLIN connects European and Russian researchers” 

    DESY
    DESY

    2015/02/06

    The European Commission has given the green light for a new collaborative project: as part of the European research program Horizon 2020, the three-year project CREMLIN (Connecting Russian and European Measures for Large-scale Research Infrastructures) will create stronger links between European and Russian research institutions in the area of large-scale facilities and enable a more intensive scientific and technological cooperation.

    1
    The neutron source PIK close to St. Petersburg (picture: PNIP).

    “With CREMLIN we bring two research landscapes, with a longstanding tradition of scientific cooperation, even closer together,” says Prof. Helmut Dosch, Chairman of the DESY Directorate.

    A total of 13 European and 6 Russian research centers and institutions will join forces in the 1.7-million-euro project which seeks to improve the integration and facilitate the exchange between Europe and Russia. Scientific research programs , international access to various facilities or technical expertise will be matched with each other and coordinated into different work packages ” began with the Ioffe Röntgen Institute, a DESY-Kurchatov cooperation, will be extended by this project throughout all of Europe and Russia ,” says Martin Sandhop (DESY), who is coordinating the project.

    For some time, Russia has been planning the construction of new large-scale research facilities on its own soil. While Russia participates in European research facilities such as the European XFEL, FAIR, ESRF or in the LHC experiments at CERN, CREMLIN should also support European scientists to become engaged in major Russian projects. For example, the research program of the planned Russian Research Reactor PIK, close to St. Petersburg, can be coordinated with those of European neutron sources, or the ion acceleration system NICA could be aligned with FAIR.

    “Without scientific, technical and financial collaboration on an international level, the complex and large-scale research projects of today and tomorrow will not be achievable,“ says Helmut Dosch. “DESY is therefore proud to coordinate such a creative collaboration project, and we look forward to fruitful discussions with our Russian partners.” The project, which received excellent marks in its Commission assessment, is to be launched in autumn 2015.

    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 4:42 pm on October 13, 2014 Permalink | Reply
    Tags: , , DESY,   

    From physicsworld: “Dark matter could light up giant mirror” 

    physicsworld
    physicsworld.com

    Oct 13, 2014
    Edwin Cartlidge

    A large metallic mirror previously used as a prototype for a cosmic-ray observatory will be reused by physicists in Germany to hunt for “hidden photons”. These exotic and hitherto unseen cousins of normal photons could account for some dark matter – the mysterious and invisible substance that appears to account for about 85% of the matter in the universe.

    Most dark-matter experiments try to detect weakly interacting massive particles (WIMPs), which are predicted by the theory of supersymmetry and interact with other matter only via the weak nuclear force and gravity. WIMP detectors aim to capture the tiny amounts of energy given off in collisions between the putative particles and atomic nuclei – usually in large detectors deep underground. However, about a quarter of a century has passed since the first such experiment started and not a single WIMP has been unambiguously detected.

    Supersymmetry standard model
    Standard Model of Super Symmetry

    Hidden photons are predicted in some extensions of the Standard Model of particle physics, and unlike WIMPs they would interact electromagnetically with normal matter. Hidden photons also have a very small mass, and are expected to oscillate into normal photons in a process similar to neutrino oscillation. Observing such oscillations relies on detectors that are sensitive to extremely small electromagnetic signals, and a number of these extremely difficult experiments have been built or proposed.

    Many different experiments

    “In the last few years, the interest in hidden photons has been growing,” says Jonathan Feng of the University of California, Irvine – partly because searches for other dark-matter candidates have “come up empty”. Also, physicists have realized that many different kinds of experiment can be built to try and detect hidden photons.

    Now, Babette Döbrich and colleagues at DESY in Hamburg, the Karlsruhe Institute for Technology and other institutes in Europe are using a portion of a spherical, metallic mirror to look for hidden photons. This was suggested in 2012 by physicists in Germany in a paper called Searching for WISPy Cold Dark Matter with a Dish Antenna. The scheme exploits the fact that hidden photons would interact with electrons – albeit feebly – and when they strike a conductor they would set the constituent electrons vibrating. These vibrations would result in normal photons being emitted at right angles to the conductor’s surface.

    A spherical mirror is ideal for detecting such light because the emitted photons would be concentrated at the sphere’s centre, whereas any background light bouncing off the mirror would pass through a focus midway between the sphere’s surface and centre. A receiver placed at the centre could then pick up the dark-matter-generated photons, if tuned to their frequency – which is related to the mass of the incoming hidden photons – with mirror and receiver shielded as much as possible from stray electromagnetic waves.

    Ideal mirror at hand

    mirror
    Reflecting on dark matter: giant mirror will seek dark matter

    Fortunately for the team, an ideal mirror is at hand: a 13 m2 aluminium mirror used in tests during the construction of the Pierre Auger Observatory and located at the Karlsruhe Institute of Technology. Döbrich and co-workers have got together with several researchers from Karlsruhe, and the collaboration is now readying the mirror by adjusting the position of each of its 36 segments to minimize the spot size of the focused waves. They are also measuring background radiation within the shielded room that will house the experiment. As for receivers, the most likely initial option is a set of low-noise photomultiplier tubes for measurements of visible light, which corresponds to hidden-photon masses of about 1 eV/C2. Another obvious choice is a receiver for gigahertz radiation, which corresponds to masses less than 0.001 eV/C2; however, this latter set-up would require more shielding.

    The DESY/Karlsruhe experiment – provisionally named FUNK (Finding U(1)’s of a Novel Kind) – will not be the first to search for hidden photons. The CERN Resonant WISP Search (CROWS) at the CERN laboratory in Geneva, which has been running since 2011, looks for both hidden photons and other low-mass dark-matter particles, such as axions. Also looking is the Axion Dark Matter Experiment at the University of Washington in Seattle. Although, as its name suggests, this facility has been set up mainly to detect axions, it can nevertheless probe the existence of hidden photons down to very low interaction strengths. The advantage of FUNK over its rivals, says Döbrich, is that it will be able to operate across quite a broad range of frequencies – just how broad will depend on the availability of suitable electromagnetic detectors and the performance of the mirror.

    Fritz Caspers of CERN applauds FUNK’s “very nice” design, but has concerns about how difficult it will be in practice to shield the mirror from electromagnetic interference. “The devil is always in the detail,” he says. He also wonders why Döbrich and colleagues did not “go directly” to look for emitted radio-frequency radiation using a radio telescope, with a dish up to perhaps 100 m across, rather than the smaller version they will use. “You could easily find much bigger mirrors in the world,” he says. Döbrich points out that in terms of optical measurements, their mirror is a very good choice.

    The research is described in a preprint on arXiv.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

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  • richardmitnick 9:04 am on October 9, 2014 Permalink | Reply
    Tags: , DESY,   

    From DESY: “How ceramics get super-tough” 

    DESY
    DESY

    09.10.2014
    No Writer Credit

    Scientists find new toughening mechanism

    Researchers have identified a previously unknown mechanism that makes a rare kind of ceramics super-tough. The findings may show a way to compose super-hard and super-tough ceramics for industrial application, as the team around DESY scientist Dr. Nori Nishiyama reports in the journal Scientific Reports.

    image
    At the fractures wormlike structures made of amorphous silica form (center). Credit: Nori Nishiyama/DESY

    The researchers investigated a material called stishovite, a rare version of silica that forms under high pressure for instance in meteorite impacts and inside the earth below about 300 kilometres of depth. Stishovite is a ceramic of the oxide group. “It is the hardest oxide known to date, even harder than ruby or sapphire,” says Nishiyama. While ceramics in general can be very hard, they tend to be very brittle also, breaking easily. Its brittleness prevented stishovite from being used industrially.

    But in 2012, Nishiyama and co-workers had synthesized nanocrystals of stishovite and could show that bulk stishovite made up of such nanocrystals is not only very hard, but also becomes very tough, reaching the toughness of zirconia, the toughest ceramic known. The reason for this toughening of stishovite remained elusive until recently.

    With a clever combination of electron microscopy and X-ray investigations at DESY’s synchrotron light source PETRA III (beamline P02.1) and at the Japanese synchrotron light source SPring-8, the researchers could now identify the previously unknown mechanism that makes nanocrystalline stishovite so exceptionally tough. Stishovite forms under high pressure and is only metastable under ambient conditions. Metastable means that if enough energy is added in some form (for instance via a fracture or via high temperature), it switches to a different configuration.

    petra iii
    Petra III

    SPring8 Japan
    SPring-8

    Stishovite uses the energy from a fracture to switch from a tetragonal crystal into amorphous silica, as the researchers found. “Actually, the transformation from stishovite to amorphous silica resembles the melting of ice,” explains Nishiyama. “Both are crystal-to-amorphous transformations that occur outside the stability field.”

    The scientists had produced nanocrystalline bulk stishovite and ripped it apart. They then looked at the fracture sites with an electron microscope. The investigation revealed worm like silica structures that proved to be an amorphous phase of silica. “These ‘worms’ have diameters of some tens of nanometres,” says Nishiyama. Using X-ray spectroscopy the team could show that about half of the surface in the fracture area is covered by amorphous silica. The more amorphous silica was present, the tougher the fracture area got. This result indicates that the fracture-induced transition to amorphous silica indeed caused the toughening of the stishovite.

    “This transition instantaneously doubles the volume of the material, effectively pushing against the fracture and stopping it short,” explains Nishiyama. In a similar way zirconia gets its toughness. On a fracture, it switches from one crystal structure (tetragonal) to another (monoclinic), expanding its volume by 4 per cent. “The transition now observed in stishovite expands the volume by 100 per cent,” underlines Nishiyama. “It may be possible to create ceramics composites for industrial use that can exploit the toughening mechanism of stishovite.”

    The work was supported by the Japan Science and Technology Agency (JST) within the program “Precursory Research Embryonic Science and Technology” (PRESTO) under the program title “New Materials Science and Element Strategy” (research supervisor Prof. Hideo Hosono).

    See the full article here.

    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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  • richardmitnick 3:27 pm on September 15, 2014 Permalink | Reply
    Tags: , , DESY, ,   

    From DESY: “Double topping-out celebrations at DESY” 

    DESY
    DESY

    Two new experimental halls for research light source PETRA III

    Today DESY celebrates the topping-out of two large experimental halls for the research light source PETRA III.Ten additional beamlines, which will serve in the PETRA III particle accelerator’s high intensity X-ray experiments, are under construction in a space measuring approximately 6000 square meters; the facility will also include en-suite offices and laboratory spaces for scientists.The experimentation capabilities at the PETRA III synchrotron radiation source will be considerably increased due to the expansion project.The first new beamlines of the 80-million-Euro-project will be ready for operation beginning in autumn 2015.
    Zoom (17 KB)

    pit

    “With the new experimental stations, we are significantly expanding the research capabilities of PETRA III, for example, with new nanospectroscopy and materials research technologies,” says Chairman of the DESY Board of Directors Professor Helmut Dosch at the event. “At the same time, we will be fulfilling the enormous worldwide scientific demand for the best synchrotron radiation source in the world.”

    Hamburg´s Science Senator Dr. Dorothee Stapelfeldt says: “The senate’s aim is to develop Hamburg into one of the leading locations for research and innovation in Europe.In order to do so, it is essential to further raise the profiles of universities and research institutions in close dialogue with all stakeholders.Hamburg already occupies a leading position in structural research.The ground-breaking cooperation between DESY, the university and their partners at the Bahrenfeld research campus has been clearly recognized internationally.With the two new experimental halls, PETRA’s synchrotron radiation will be made available to even more researchers from all over the world in the future.”

    “With a total of ten new beamlines, the allure of Hamburg as a location for cutting-edge research will continue to increase, nationally and internationally,” says Dr. Beatrix Vierkorn-Rudolph (BMBF), Chairperson of the DESY Foundation Council. “With its excellent research opportunities, PETRA III contributes to rapidly transfering the results of basic research into application while also strengthening the innovative power of Germany.”

    DESY’s 2.3-kilometre-long PETRA III ring accelerator produces high intensity, highly collimated X-ray pulses for a diverse range of physical, biological and chemical experiments.Fourteen measuring stations, which can accommodate up to thirty experiments, already exist in an approximately 300-metre-long experimental hall.The properties of light pulses, which PETRA delivers to the different measuring stations, are thereby precisely attuned to the different research disciplines.Using the extremely brilliant X-rays, researchers study, for example, innovative solar cells, observe the dynamics of cell membranes and analyse fossilised dinosaur eggs.

    PETRA III, the world´s best X-ray source of its kind, has been heavily over-booked since it began operations in 2009.The PETRA III Extension Project was begun in December 2013 to give more scientists access to the unique experimental possibilities of this research light source and to broaden PETRA III’s research portfolio in experimental technologies:measuring approximately 6000 square meters in their entirety, the two new experimental halls house enough space for technical installations of up to ten additional beam lines, and an additional 1400 square metres provide office and laboratory space for the scientists.The beam lines and measuring instruments in the new halls are under construction in close cooperation with the future user community and are, in part, collaborative research projects.Three of the future PETRA beamlines will be constructed as an international partnership with Sweden, India and Russia.

    Altogether approximately 170 metres of the PETRA tunnel and accelerator have been dismantled since February to build the new experimental halls. Since August, the accelerator, equipped with special magnets for producing X-ray radiation, has been under reconstruction within the new tunnel areas that have already been completed.After the preliminary construction phase of the experimental halls, they are to be developed further from December 2014 onward; the accelerator will at the same time resume operation.The experiments will re-start in the PETRA III experimental hall “Max von Laue” beginning in April 2015 and the first measuring stations in the new, still unnamed halls should gradually become ready for operation in autumn 2015 and the start of 2016.

    The extension’s total budget of approximately 80 million Euros stems in large part from the Helmholtz Association’s expansion funds as well as funds from the Federal Ministry of Research, the Free and Hanseatic City of Hamburg and DESY.Collaborative partners from Germany and abroad cover approximately one third of the costs.

    See the full article here.

    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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