Tagged: DESY Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 8:15 am on August 14, 2018 Permalink | Reply
    Tags: DESY, , PITZ accelerator-Photo Injector Test facility at DESY's Zeuthen site, Plasma-based particle acceleration   

    From DESY: “World record – Low-draft electron bunches drive high plasma wakes” 

    DESY
    From DESY

    2018/08/13

    Scientists at DESY have achieved a milestone towards the usability of novel, plasma-based particle accelerators. Using the electron beam of the PITZ accelerator, the Photo Injector Test facility at DESY’s Zeuthen site, DESY physicist Frank Stephan and his group, as part of the LAOLA collaboration, accelerated electrons in a plasma wake with an enhanced ratio between acceleration of the witness and deceleration of the driver beam. This so-called transformer ratio defines the achievable energy gain in such a plasma accelerator. Their results are now being published in the journal Physical Review Letters.

    1
    DESY – PITZ – Deutsches Elektronen-Synchrotron DESY The Photo Injector Test Facility at the DESY location in Zeuthen

    2
    The plasma cell used for the experiments. The glass tube is ten centimetres long, about seven centimetres are visible here. Credit: DESY, Gregor Loisch

    Plasma-based particle acceleration is a novel accelerator technology which utilizes the possibility to achieve accelerating field strengths in a plasma which exceed those of conventional accelerators by three orders of magnitude. In the case of the Plasma Wakefield Acceleration scheme, a pair of two electron bunches are shot into an ionized gas (plasma) where the first, highly energetic “driver”-bunch drives a plasma wake. The second, “witness” bunch, which trails the first one with about five picoseconds (millionth of a millionth second) delay, is accelerated in the plasma wake like a surfer who rides the wake of a boat.

    The electrons which drive the plasma wake are being decelerated in the process and act as the energy source for the acceleration. The ratio between acceleration and deceleration is the above-mentioned transformer ratio. A high transformer ratio corresponds to a boat, that slides lightly through the water but creates a high wake at its stern. For the electron beams that have been used in plasma wakefield experiments so far, the transformer ratio is limited to 2. The experiments at PITZ aimed at breaking this limit, which was possible by using the specially formed electron bunches that are available at PITZ. Using the flexible photocathode laser of the facility, the researchers were able to investigate plasma acceleration by asymmetric, triangularly shaped driver bunches for the first time. With this crucial improvement, a transformer ratio of 4.6 was measured, exceeding previous experiments significantly.

    3
    The simulation of the beam plasma interaction shows the driver beam electrons (red), the witness beam electrons (green) and the accelerating plasma wakefield (colored surface). Credit: DESY, Gregor Loisch

    “Application of our technique could reduce the length of a future plasma accelerator by more than half”, says Gregor Loisch, lead author of the study. “Now that we know that such high transformer ratios are generally possible, we’ll refine our methods to achieve this at higher accelerating fields.”

    Especially the high achievable accelerating field strength makes plasma acceleration one of the most promising candidates for novel particle accelerators. Increasing the field strength allows to shrink the acceleration length at constant acceleration energy, which would reduce the cost for building and operating such a future facility.

    The studies performed at PITZ, could allow to also shrink the energy of the required conventional driver beam accelerator and reduce the costs further.

    Today, only few facilities in the world are capable of producing the flexible electron beams needed for this. Other crucial assets of the research accelerator PITZ besides its bunch shaping capabilities are the various diagnostics to accurately measure the electron beams and the possibility to supply sufficient beam time for such accelerator experiments.

    In addition to increasing the relatively moderate acceleration field strength of currently 3.6 megavolts per metre (MV/m), the scientists will focus on improving the bunch shaping flexibility in further studies.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    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.

    DESY Petra III interior


    DESY Petra III

    DESY/FLASH

    H1 detector at DESY HERA ring

    DESY DORIS III

    Advertisements
     
  • richardmitnick 9:56 am on May 28, 2018 Permalink | Reply
    Tags: CALICE collaboration, Calorimeter systems, Calorimeters measure the energy of passing particles from a collision, DESY, Hadronic calorimeter, , ,   

    From DESY: “Detector prototype sees beam” 

    DESY
    From DESY

    Optimised from top to bottom: new calorimeter produces good results in the test beam.

    1
    The calorimeter was assembled at DESY. Image: DESY

    2
    Test beam crew at CERN. Image: Jiri Kvasnicka, Prag

    Particle physics will always need calorimeters, so particle physicists are always trying to optimise, tweak and update their calorimeter systems for the best possible measurements. The CALICE collaboration plays a leading role in this, and their most recent prototype for a hadronic calorimeter has just been completed and is currently at CERN for a round of tests in the test beam.

    The project leaders are Katja Krüger and Felix Sefkow from DESY, who coordinated the development and production of all parts for the new prototype. They made sure it all came together in the detector lab at DESY and used the local expertise of many different groups to check that it worked wand set off with it to CERN. And it’s not only DESY electronics expertise that was involved: the calorimeter made the journey packaged in neat crates designed and custom-made by the DESY carpenters.

    The calorimeter prototype, whose role it is to measure the energy of passing particles from a collision, consists of 38 layers of 72 by 72 centimetres of active material. 22 000 scintillator tiles, each with its own silicon photomultiplier (SiPM), measure the passing particles, and in contrast to previous prototypes everything is included in the structure: photosensors, readout chips, LEDs for calibration, voltage adjustment, trigger, storage, amplifiers, energy and time digitisers, you name it. All of the data recorded by the detectors leaves the structure via one neat cable – just like it would have to if it were part of a complete high-energy physics particle detector where there’s no space for racks and lots of cables.

    2
    Representation of particles in the detector. No image credit.

    Coordinator Felix Sefkow explains what makes this calorimeter so special. “It’s got the 4D position information and timing of an imaging detector and it’s a calorimeter at the same time.” The new prototype is the culmination of years of developing and testing various technologies and combinations of technologies in labs and test beams to find the optimal system combinations and use the latest developments from semi-conductor industry. With its mature technology it could in principle be installed in a detector for the ILC tomorrow. So far things have gone well in the test beam that just finished after two weeks at CERN.

    Assembly of the detector had started in October last year with the participation of many groups around the world, using mass-production technologies. The scintillator tiles themselves were injection-moulded in Russia, automatically wrapped like candies in Hamburg and glued onto electronics boards by a robot in Mainz. The complex boards were assembled at DESY, using ASICs from the OMEGA group at Palaiseau, tested in Wuppertal, and SiPMs from Japan, characterised in Heidelberg.

    The DAQ was a common effort of Bristol, Prague and DESY physicists. Board production went on until January, after which they were calibrated, tested and integrated into the calorimeter structure at DESY. The Max-Planck-Group Munich contributed to mechanics and gave the software a strong boost. And before being packed up into boxes for the CERN beam time the setup already recorded its first cosmic muon events.

    Installation in CERN’s SPS beam line H2 went smoothly, the detector worked out of the box and recorded tens of millions of muon, electron and pion events. “Online data quality looks good”, summarises Krüger.

    The CALICE SiPM-on-Tile technology, developed under DESY lead, is so versatile that it will also be used in the LHC’s CMS detector for the high-luminosity upgrade and is under consideration for a future neutrino detector in the United States.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.
    stem
    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 3:42 pm on May 5, 2018 Permalink | Reply
    Tags: , , , DESY, , Freeze-framing nanosecond movements of nanoparticles, , ,   

    From DESY: “Freeze-framing nanosecond movements of nanoparticles” 

    DESY
    From DESY

    2018/05/03
    No writer credit

    New method allows to monitor fast movements at hard X-ray lasers.

    A team of scientists from DESY, the Advanced Photon Source APS and National Accelerator Laboratory SLAC, both in the USA, have developed and integrated a new method for monitoring ultrafast movements of nanoscopic systems.

    Argonne APS

    SLAC LCLS

    With the light of the X-ray laser LCLS at the research center SLAC in California, they took images of the movements of nanoparticles taking only the billionth of a second (0,000 000 001 s).

    SLAC LCLS

    In their experiments now published in the journal Nature Communications they overcame the slowness of present-day two-dimensional X-ray detectors by splitting individual laser flashes of LCLS, delaying one half of it by a nanosecond and recording a single picture of the nanoparticle with these pairs of X-ray pulses. The tunable light splitter for hard X-rays which the scientists developed for these experiments enables this new technique to monitor movements of nanometer size fluctuations down to femtoseconds and at atomic resolution. For comparison: modern synchrotron radiation light sources like PETRA III at DESY can typically measure movements on millisecond timescales.

    DESY Petra III interior

    1
    Scheme of the experiment: An autocorrelator developed at DESY splits the ultrashort X-ray laser pulses into two equal intensity pulses which arrive with a tunable delay at the sample. The speckle pattern of the sample is collected in a single exposure of the 2-D detector (picture: W. Roseker/DESY).

    he intense light flashes of X-ray lasers are coherent which means that the waves of the monochromatic laser light propagate in phase to each other. Diffracting coherent light by a sample usually results in a so-called speckle diffraction pattern showing apparently randomly ordered light spots. However, this speckle is also a map of the sample arrangement, and movements of the sample constituents result in a different speckle pattern.

    For their experiments the researchers developed a special optical setup – a so-called optical autocorrelator – capable of splitting 100 femtosecond long XFEL pulses into two sub-pulses, deviate them into separated detours and recombining their paths with a tunable time delay between zero and a few nanoseconds. These pairs of XFEL pulses hit the sample with the tuned delay, spotting the sample´s structure at the two exposure times. The sum of both speckle pictures was recorded by a two-dimensional photon detector within one exposure time. The trick: If the constituents of the sample move during the two illuminations, the speckle pattern changes, resulting in an integrated picture of less contrast at the detector. The contrast is a measure on how strong the photon intensity varies on the detector. However, the intensity and especially the intensity difference measured at the detector are very weak. In their experiments the researchers had to work with only some 1000 detected photons on the one-million-pixels size detector.

    “Such type of experiments has been done for much slower movements of nanoparticles at storage ring light sources,” explains first author Wojciech Roseker from DESY. “But now, the high coherence and intensity of the X-ray laser light at XFELs open up the opportunity to get pictures bright enough to provide reasonable information about quick movements in the nanosecond to femtosecond regime.”

    In their work the researchers around Roseker used a suspension of two nanometers size gold particles undergoing Brownian motion. The experiment was in perfect agreement with the theoretical predictions thus proving not only the performance of the autocorrelator setup but also the validity of the data analysis procedure, demonstrating the first successful experiment of this kind. One of the challenges in this experiment, carried out at the XCS experimental station at LCLS, was to autocorrelate thousands of extremely weak double shot 2D images which was achieved with the help of a newly developed maximum likelihood analysis technique.

    “This experiment paves the way to dynamics experiments of materials on atomic length and femtosecond-nanosecond timescales,” explains Gerhard Grübel, head of the DESY FS-CXS group. “Split-pulse X-ray Photon Correlation Spectroscopy (XPCS) can potentially track atomic scale fluctuations in liquid metals, multi-scale dynamics in water, heterogeneous dynamics about the glass transition, and atomic scale surface fluctuations.” Additionally, time-domain XPCS at FEL sources, especially at the European XFEL, is well suited for studying fluctuations in non-equilibrium processes that go beyond time-averaged structural descriptions.


    DESY European XFEL


    European XFEL

    This will allow the elucidation of dynamics of ultrafast magnetization processes and can address open questions concerning photo-induced phonon dynamics and phase transitions.

    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 4:37 pm on April 6, 2018 Permalink | Reply
    Tags: , , , DESY, , , , ,   

    From DESY: “Electron beams that chop themselves” 

    DESY
    DESY

    2018/04/06

    First experimental proof of self-modulation of particle bunches.

    1
    View through the plasma cell along the flight path of the electron beam. Visible in the middle is the pink glow of the plasma. Credit: DESY, Johannes Engel.

    In a multi-national effort a team of researchers from DESY, the Lawrence Berkeley National Laboratory (LBNL) and other institutes have demonstrated a remarkable feature of self-organisation in a particle beam that can be of great use for a future generation of compact accelerators: Using the high quality electron beam at DESY’s PITZ facility, the scientists could show that long electron bunches can chop themselves into a row of shorter bunches when they fly through a cloud of electrically charged gas, called a plasma.

    At the same time the electrons’ energies were seen to be modulated along each bunch. These results are the experimental proof of a novel plasma acceleration concept pursued by the AWAKE (Advanced Wakefield Experiment) collaboration at the European particle physics lab CERN in Geneva. The team led by DESY scientist Matthias Groß presents its findings in the journal Physical Review Letters.

    Particle accelerators at the energy frontier like the Large Hadron Collider (LHC) at CERN are extremely costly to build and operate.

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    Nevertheless there is strong interest to increase available beam energies even further to refine the standard model of particle physics and discover physics beyond. Plasma wakefield accelerators could be the answer to this problem. Today’s bulky structures could be replaced with millimetre-sized plasmas enabling several orders of magnitude stronger acceleration.

    To accelerate an electron bunch in this way the plasma electrons are separated from the plasma molecules, forming a so-called plasma wakefield that creates an immense accelerating field. The separation of electrons and molecules in the plasma can be achieved through a high-energy bunch of charged particles. Using proton bunches is very attractive since sufficient energy can be stored in a proton beam to drive a plasma accelerator and generate electron bunches with energies in the LHC regime of tera-electronvolts (TeV) in a single stage. The AWAKE experiment is hosted by CERN to investigate this promising scheme. However, proton bunches as they are generated in today’s accelerators are much too long to be useful in plasma accelerators. Therefore, the generation of suitable proton bunches from a conventional accelerator is a key issue for the AWAKE setup.

    CERN AWAKE

    CERN AWAKE

    2
    A self-modulated electron bunch. Credit: DESY

    This task can be accomplished by utilising the so-called self-modulation instability. In this case a plasma wave is initiated at or near the front of the bunch and the resulting electric fields lead to the desired re-organisation of the particle bunches in the beam. This self-modulation effect was described in theory and simulation, but so far only indirect indications were observed in experiment. This is where the unique capabilities of the PITZ facility comes into play, explains group leader Frank Stephan: “The combination of a flexible photocathode laser, high electron beam quality and excellent diagnostics made it possible to demonstrate this effect unambiguously for the first time.” The measurements showed that an incident long electron bunch split itself into three smaller bunches.

    1
    DESY PITZ

    ”The breakthrough results described in our manuscript can be scaled directly to the proton regime and thus open the path to validate the self-modulation scheme towards the next-generation of high-energy physics accelerators at CERN,” emphasises main author Matthias Groß. “Our positive results show that the self-modulation can be practically used in experiments and that unwanted effects like beam hosing, which tend to destroy particle bunches, can be kept under control. This experimental data has been eagerly anticipated in the plasma wakefield accelerator community, especially by the AWAKE collaboration, for several years. The presented achievement is a further example where a plasma wakefield theory based prediction is directly validated in experiment. And looking ahead, our special cross shaped plasma cell which was utilized to gain these results may be of great interest to other groups working on beam-driven plasma wakefield acceleration as well.”

    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 2:58 pm on December 8, 2017 Permalink | Reply
    Tags: DESY, Novel Lenses Enable X-ray Microscopy With Record Resolution, The new lenses consist of over 10 000 alternating layers of a new material combination, These lenses consist of alternating layers of two different materials with nanometre thickness   

    From DESY: “Novel Lenses Enable X-ray Microscopy With Record Resolution” 

    DESY
    DESY

    2017/12/07
    No writer credit

    DESY team generates X-ray focus below 10 nanometres diameter.

    1
    The silica shell of the diatom Actinoptychus senarius, measuring only 0.1 mm across, is revealed in fine detail in this X-ray hologram recorded at 5000-fold magnification with the new lenses. The lenses focused an X-ray beam to a spot of approximately eight nanometres diameter – smaller than a single virus – which then expanded to illuminate the diatom and form the hologram. Credit: DESY/AWI, Andrew Morgan/Saša Bajt/Henry Chapman/Christian Hamm

    Scientists at DESY have developed novel lenses that enable X-ray microscopy with record resolution in the nanometre regime. Using new materials, the research team led by DESY scientist Saša Bajt from the Center for Free-Electron Laser Science (CFEL) has perfected the design of specialised X-ray optics and achieved a focus spot size with a diameter of less than ten nanometres.

    3
    Center for Free-Electron Laser Science (CFEL)

    A nanometre is a millionths of a millimetre and is smaller than most virus particles. The researchers report their work in the journal Light: Science and Applications . They successfully used their lenses to image samples of marine plankton.

    Modern particle accelerators provide ultra-bright and high-quality X-ray beams. The short wavelength and the penetrating nature of X-rays are ideal for the microscopic investigation of complex materials. However, taking full advantage of these properties requires highly efficient and almost perfect optics in the X-ray regime. Despite extensive efforts worldwide this turned out to be more difficult than expected, and achieving an X-ray microscope that can resolve features smaller than 10 nm is still a big challenge.

    Due to their unique properties X-rays cannot be focused as easily as visible light. One way is to use specialised X-ray optics called multilayer Laue lenses (MLLs). These lenses consist of alternating layers of two different materials with nanometre thickness. They are prepared with a coating process called sputter deposition. In contrast to conventional optics, MLLs do not refract light but work by diffracting the incident X-rays in a way that concentrates the beam on a small spot. To achieve this, the layer thickness of the materials has to be precisely controlled. The layers must gradually change in thickness and orientation throughout the lens. The focus size is proportional to the smallest layer thickness in the MLL structure.

    To meet the required precision, Bajt’s team combined a novel fabrication process with detailed understanding of the material properties, which often vary with layer thickness. The new lenses consist of over 10 000 alternating layers of a new material combination, tungsten carbide and silicon carbide. “The selection of the right material pair was critical for the success,” emphasises Bajt. “It does not exclude other material combinations but it is definitely the best we know now.”

    To focus an X-ray beam in the vertical and horizontal directions it has to pass through two perpendicularly oriented lenses. By using this set-up, a spot size of 8.4 nanometres by 6.8 nanometres was measured at the Hard X-ray Nanoprobe experimental station at the National Synchrotron Light Source NSLS II at Brookhaven National Laboratory in the U.S.


    BNL NSLS II

    The focus size is what sets the resolution of the X-ray microscope. The resolution of the new lenses is about five times better than achievable with typical state-of-the-art lenses.

    2
    For imaging investigations, two perpendicularly oriented lenses focus the X-ray beam into a small spot. The object under investigation (not shown here) can then be placed into the optical path and its image recorded by the detector. Credit: DESY, Andrew Morgan/Saša Bajt

    “We produced the world’s smallest X-ray focus using high efficiency lenses,” says Bajt. Due to their penetrating nature, X-rays would usually pass straight through the lens materials. Such rays obviously do not contribute to the focus, and thus a long-term goal has been to produce lens structures that enhance the interaction with X-rays, to direct a high fraction into the focus. The new lenses have an efficiency of more than 80 per cent. This high efficiency is achieved with the layered structures that make up the lens and which act like an artificial crystal to diffract X-rays in a controlled way.

    The high efficiency achieved here demonstrates the very high level of control in the production of the necessary nanometre structures. This accuracy allows projection imaging over a large range of magnifications as demonstrated by tests of the novel lenses. At beamline P11 of DESY’s X-ray source PETRA III the scientists produced high-resolution holograms of Acantharea, single-celled Radiolaria belonging to marine plankton and the only organisms known to form skeletons from the mineral strontium sulfate (SrSO4) or celestite.

    DESY Petra III

    Bajt’s team has also used the new lenses to image the biomineralized shells of marine planktonic diatoms. These single-celled organisms have intricate shells, which are highly complex stable but also lightweight constructions. They consist of nanostructured silica, which was observed in two dimensional analyses with electron microscopes before. Most likely because of this structuring, the strength of the silica is exceptionally high – ten times higher than that of construction steel – although it is produced under low temperature and pressure conditions.

    “We hope that the novel X-ray optics will soon make it possible to image these nanostructures in 3D. This will enable us to model and understand the high mechanical performance of these shells and help us to develop new, environmentally friendly and high performance materials,” says Christian Hamm from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), who provided the samples and is a co-author of this study.

    The new lenses can be used in a wide range of applications including nano-resolution imaging and spectroscopy. “These MLLs open up new and exciting opportunities in X-ray science. They can be designed for different energies and used with coherent sources, such as X-ray free-electron lasers,” says Bajt. “This great achievement would not have been possible without a wonderful team with expertise in X-ray optics and theory, nanofabrication, material science, data processing and instrumentation. Since we now know how to optimise the lens design, our work paves the way to ultimately reach the goal of one nanometre resolution in X-ray microscopy.”

    Scientists from DESY, the University of Hamburg, the National Science Foundation BioXFEL Science and Technology Center in the U.S., Arizona State University in the U.S., the University of Bialystok in Poland, Brookhaven National Laboratory in the U.S., and Alfred Wegener Institute in Germany were involved in this study. CFEL is a cooperation of DESY, the University of Hamburg and the German Max Planck Society.

    Reference:
    X-ray focusing with efficient high-NA multilayer Laue lenses; Saša Bajt et al.;Light: Science and Applications (accepted article preview; 25,6MB, slow server!)

    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 12:01 pm on June 19, 2017 Permalink | Reply
    Tags: , , DESY, , First atomic structure of an intact virus deciphered with an X-ray laser, ,   

    From DESY: “First atomic structure of an intact virus deciphered with an X-ray laser” 

    DESY
    DESY

    2017/06/19

    Groundbreaking experimental method will speed up protein analysis substantially.

    1
    Surface structure of the bovine enterovirus 2, the three virus proteins are colour coded. Credit: Jingshan Ren, University of Oxford

    An international team of scientists has for the first time used an X-ray free-electron laser to unravel the structure of an intact virus particle on the atomic level. The method used dramatically reduces the amount of virus material required, while also allowing the investigations to be carried out several times faster than before. This opens up entirely new research opportunities, as the research team lead by DESY scientist Alke Meents reports in the journal Nature Methods.

    In the field known as structural biology, scientists examine the three-dimensional structure of biological molecules in order to work out how they function. This knowledge enhances our understanding of the fundamental biological processes taking place inside organisms, such as the way in which substances are transported in and out of a cell, and can also be used to develop new drugs.

    “Knowing the three-dimensional structure of a molecule like a protein gives great insight into its biological behaviour,” explains co-author David Stuart, Director of Life Sciences at the synchrotron facility Diamond Light Source in the UK and a professor at the University of Oxford. “One example is how understanding the structure of a protein that a virus uses to ‘hook’ onto a cell could mean that we’re able to design a defence for the cell to make the virus incapable of attacking it.”

    X-ray crystallography is by far the most prolific tool used by structural biologists and has already revealed the structures of thousands of biological molecules. Tiny crystals of the protein of interest are grown, and then illuminated using high-energy X-rays. The crystals diffract the X-rays in characteristic ways so that the resulting diffraction patterns can be used to deduce the spatial structure of the crystal – and hence of its components – on the atomic scale. However, protein crystals are nowhere near as stable and sturdy as salt crystals, for example. They are difficult to grow, often remaining tiny, and are easily damaged by the X-rays.

    “X-ray lasers have opened up a new path to protein crystallography, because their extremely intense pulses can be used to analyse even extremely tiny crystals that would not produce a sufficiently bright diffraction image using other X-ray sources,” adds co-author Armin Wagner from Diamond Light Source. However, each of these microcrystals can only produce a single diffraction image before it evaporates as a result of the X-ray pulse. To perform the structural analysis, though, hundreds or even thousands of diffraction images are needed. In such experiments, scientists therefore inject a fine liquid jet of protein crystals through a pulsed X-ray laser, which releases a rapid sequence of extremely short bursts. Each time an X-ray pulse happens to strike a microcrystal, a diffraction image is produced and recorded.

    This method is very successful and has already been used to determine the structure of more than 80 biomolecules. However, most of the sample material is wasted. “The hit rate is typically less than two per cent of pulses, so most of the precious microcrystals end up unused in the collection container,” says Meents, who is based at the Center for Free-Electron Laser Science (CFEL) in Hamburg, a cooperation of DESY, the University of Hamburg and the German Max Planck Society. The standard method therefore typically requires several hours of beamtime and significant amounts of sample material.

    3
    Micrograph of the microstructured chip, loaded with crystals for the investigation. Each square is a tiny crystal. Credit: Philip Roedig, DESY

    n order to use the limited beamtime and the precious sample material more efficiently, the team developed a new method. The scientists use a micro-patterned chip containing thousands of tiny pores to hold the protein crystals. The X-ray laser then scans the chip line by line, and ideally this allows a diffraction image to be recorded for each pulse of the laser.

    The research team tested its method on two different virus samples using the LCLS X-ray laser at the SLAC National Accelerator Laboratory in the US, which produces 120 pulses per second.

    SLAC/LCLS

    They loaded their sample holder with a small amount of microcrystals of the bovine enterovirus 2 (BEV2), a virus that can cause miscarriages, stillbirths, and infertility in cattle, and which is very difficult to crystallise.

    In this experiment, the scientists achieved a hit rate – where the X-ray laser successfully targeted the crystal – of up to nine per cent. Within just 14 minutes they had collected enough data to determine the correct structure of the virus – which was already known from experiments at other X-ray light sources – down to a scale of 0.23 nanometres (millionths of a millimetre).

    “To the best of our knowledge, this is the first time the atomic structure of an intact virus particle has been determined using an X-ray laser,” Meents points out. “Whereas earlier methods at other X-ray light sources required crystals with a total volume of 3.5 nanolitres, we managed using crystals that were more than ten times smaller, having a total volume of just 0.23 nanolitres.”

    This experiment was conducted at room temperature. While cooling the protein crystals would protect them to some extent from radiation damage, this is not generally feasible when working with extremely sensitive virus crystals. Crystals of isolated virus proteins can, however, be frozen, and in a second test, the researchers studied the viral protein polyhedrin that makes up a viral occlusion body for up to several thousands of virus particles of certain species. The virus particles use these containers to protect themselves against environmental influences and are therefore able to remain intact for much longer times.

    4
    Schematic of the experimental set-up: The chip loaded with nanocrystals is scanned by the fine X-ray beam (green) pore by pore. Ideally, each crystal produces a distinctive diffraction pattern. Credit: Philip Roedig, DESY

    For the second test, the scientist loaded their chip with polyhedrin crystals and examined them using the X-ray laser while keeping the chip at temperatures below minus 180 degrees Celsius. Here, the scientists achieved a hit rate of up to 90 per cent. In just ten minutes they had recorded more than enough diffraction images to determine the protein structure to within 0.24 nanometres. “For the structure of polyhedrin, we only had to scan a single chip which was loaded with four micrograms of protein crystals; that is orders of magnitude less than the amount that would normally be needed,” explains Meents.

    “Our approach not only reduces the data collection time and the quantity of the sample needed, it also opens up the opportunity of analysing entire viruses using X-ray lasers,” Meents sums up. The scientists now want to increase the capacity of their chip by a factor of ten, from 22,500 to some 200,000 micropores, and further increase the scanning speed to up to one thousand samples per second. This would better exploit the potential of the new X-ray free-electron laser European XFEL, which is just going into operation in the Hamburg region and which will be able to produce up to 27,000 pulses per second.

    European XFEL

    Furthermore, the next generation of chips will only expose those micropores that are currently being analysed, to prevent the remaining crystals from being damaged by scattered radiation from the X-ray laser.

    Researchers from the University of Oxford, the University of Eastern Finland, the Swiss Paul Scherrer Institute, the Lawrence Berkeley National Laboratory in the US and SLAC were also involved in the research. Diamond scientists have collaborated with the team at DESY, with much of the development and testing of the micro-patterned chip being done on Diamond’s I02 and I24 beamlines.

    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 1:44 pm on May 31, 2017 Permalink | Reply
    Tags: , , DESY, ,   

    From SLAC: “The World’s Most Powerful X-ray Laser Beam Creates ‘Molecular Black Hole’” 


    SLAC Lab

    May 31, 2017
    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282

    When the X-rays blast electrons out of one atom, stripping it from the inside out, it steals more from its neighbors – a new insight that could help advance high-res imaging of whole viruses, bacteria and complex materials.

    1
    In this illustration, an ultra-intense X-ray laser pulse from SLAC’s Linac Coherent Light Source knocks so many electrons out of a molecule’s iodine atom (right) that the iodine starts pulling in electrons from the rest of the molecule (lower left), like an electromagnetic version of a black hole. Many of the stolen electrons are also knocked out by the laser pulse; then the molecule explodes. (DESY/Science Communication Lab)

    When scientists at the Department of Energy’s SLAC National Accelerator Laboratory focused the full intensity of the world’s most powerful X-ray laser on a small molecule, they got a surprise: A single laser pulse stripped all but a few electrons out of the molecule’s biggest atom from the inside out, leaving a void that started pulling in electrons from the rest of the molecule, like a black hole gobbling a spiraling disk of matter.

    Within 30 femtoseconds – millionths of a billionth of a second – the molecule lost more than 50 electrons, far more than scientists anticipated based on earlier experiments using less intense beams or isolated atoms. Then it blew up.

    The results, published today in Nature, give scientists fundamental insights they need to better plan and interpret experiments using the most intense and energetic X-ray pulses from SLAC’s Linac Coherent Light Source (LCLS) X-ray free-electron laser.

    SLAC/LCLS

    Experiments that require these ultrahigh intensities include attempts to image individual biological objects, such as viruses and bacteria, at high resolution. They are also used to study the behavior of matter under extreme conditions, and to better understand charge dynamics in complex molecules for advanced technological applications.

    “For any type of experiment you do that focuses intense X-rays on a sample, you want to understand how it reacts to the X-rays,” said Daniel Rolles of Kansas State University. “This paper shows that we can understand and model the radiation damage in small molecules, so now we can predict what damage we will get in other systems.”

    Like Focusing the Sun Onto a Thumbnail

    The experiment, led by Rolles and Artem Rudenko of Kansas State, took place at LCLS’s Coherent X-ray Imaging instrument (CXI). It delivers X-rays with the highest possible energies achievable at LCLS, known as hard X-rays, and records data from samples in the instant before the laser pulse destroys them.

    How intense are those X-ray pulses?

    “They are about a hundred times more intense than what you would get if you focused all the sunlight that hits the Earth’s surface onto a thumbnail,” said LCLS staff scientist and co-author Sebastien Boutet.

    For this study, researchers used special mirrors to focus the X-ray beam into a spot just over 100 nanometers in diameter – about a hundredth the size of the one used in most CXI experiments, and a thousand times smaller than the width of a human hair. They looked at three types of samples: individual xenon atoms, which have 54 electrons each, and two types of molecules that each contain a single iodine atom, which has 53 electrons.

    Heavy atoms around this size are important in biochemical reactions, and researchers sometimes add them to biological samples to enhance contrast for imaging and crystallography applications. But until now, no one had investigated how the ultra-intense CXI beam affects molecules with atoms this heavy.

    X-rays Trigger Electron Cascades

    The team tuned the energy of the CXI pulses so they would selectively strip the innermost electrons from the xenon or iodine atoms, creating “hollow atoms.” Based on earlier studies with less energetic X-rays, they thought cascades of electrons from the outer parts of the atom would drop down to fill the vacancies, only to be kicked out themselves by subsequent X-rays. That would leave just a few of the most tightly bound electrons. And, in fact, that’s what happened in both the freestanding xenon atoms and the iodine atoms in the molecules.

    But in the molecules, the process didn’t stop there. The iodine atom, which had a strong positive charge after losing most of its electrons, continued to suck in electrons from neighboring carbon and hydrogen atoms, and those electrons were also ejected, one by one.

    Rather than losing 47 electrons, as would be the case for an isolated iodine atom, the iodine in the smaller molecule lost 54, including the ones it grabbed from its neighbors – a level of damage and disruption that’s not only higher than would normally be expected, but significantly different in nature.

    Results Feed Into Theory to Improve Experiments

    “We think the effect was even more important in the larger molecule than in the smaller one, but we don’t know how to quantify it yet,” Rudenko said. “We estimate that more than 60 electrons were kicked out, but we don’t actually know where it stopped because we could not detect all the fragments that flew off as the molecule fell apart to see how many electrons were missing. This is one of the open questions we need to study.”

    For the data analyzed to date, the theoretical model provided excellent agreement with the observed behavior, providing confidence that more complex systems can now be studied, said LCLS Director Mike Dunne. “This has important benefits for scientists wishing to achieve the highest-resolution images of biological molecules to inform the development of better pharmaceuticals, for example,” he said. “These experiments will also guide the development of a next-generation instrument for the LCLS-II upgrade project, which will provide a major leap in capability due to the increase in repetition rate from 120 pulses per second to 1 million.”

    SLAC LCLS-II

    The theory work for the study was led by Robin Santra of the Center for Free-Electron Laser Science at DESY and the University of Hamburg in Germany. Other research institutions contributing to the study were Tohoku University in Japan; Max Planck Institute for Nuclear Physics, Max Planck Institute for Medical Research, Hamburg Center for Ultrafast Imaging and the National Metrology Institute (PTB) in Germany; the University of Science and Technology in Beijing; Aarhus University in Denmark; Sorbonne University in France; the DOE’s Argonne National Laboratory and Brookhaven National Laboratory; the University of Chicago; and Northwestern University. Funding for the research came from the DOE Office of Science and from the German Research Foundation (DFG).

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
    i1

     
  • richardmitnick 10:20 am on April 19, 2017 Permalink | Reply
    Tags: Accelerator Consortium, , DESY, , Particle accelerator for the European XFEL X-ray laser operational, Superconducting linear accelerator,   

    From XFEL: “Particle accelerator for the European XFEL X-ray laser operational” 

    XFEL bloc

    European XFEL

    19 April 2017
    No writer credit

    World’s longest superconducting linear accelerator

    1
    View into the 2.1-kilometre long accelerator tunnel of European XFEL with the yellow superconducting accelerator modules hanging from the ceiling. Heiner Müller-Elsner / European XFEL

    The international X-ray laser European XFEL has reached one of its final major milestones on the way to scientific user operation. DESY has successfully commissioned the particle accelerator, which drives the X-ray laser along its full length.

    Accelerated electrons have passed through the complete 2.1 kilometre length of the accelerator tunnel. In the next step, the energy of the electrons will be raised further, before they will be sent into a magnetic slalom section where the bright X-ray laser light will be generated. This first lasing is planned for May. DESY is the largest shareholder of the European XFEL and is responsible for the construction and operation of the superconducting linear accelerator.

    “The European XFEL’s particle accelerator is the first superconducting linear accelerator of this size in the world to go into operation. With the commissioning of this complex machine, DESY and European XFEL scientists have placed the crown on their 20-year engagement in developing and building this large international project. The first experiments are within reach, and I am quite excited about the discoveries ahead of us”, says Chairman of the DESY Board of Directors Helmut Dosch. “I am exceptionally happy about arriving at this milestone and congratulate all involved for the outstanding work and their great tenacity.”

    Chairman of the European XFEL Management Board Robert Feidenhans’l says: “The successful commissioning of the accelerator is a very important step that brings us much closer to the start of user operation in the fall. Under the leadership of DESY, the Accelerator Consortium, comprising 17 research institutes, has done an excellent job in the last years. I thank all colleagues involved for their work, which entailed a great deal of know-how and precision but also much personal commitment. The accelerator is an outstanding example of successful global cooperation, encompassing research facilities, institutes, and universities alongside companies that produced certain components.”

    The European XFEL is an X-ray laser of superlatives: The research facility will produce up to 27 000 X-ray laser flashes per second, each so short and intense that researchers can make pictures of structures and processes at the atomic level.
    The superconducting particle accelerator of the facility, which is now operational across its full length, is the key component of the 3.4 km long X-ray laser. The accelerator’s superconducting TESLA technology, which was developed in an international collaboration led by DESY, is the basis for the unique high rate of X-ray laser flashes. Superconductivity means that the accelerator components have no electrical resistance. For this, they have to be cooled to extremely low temperatures.

    From December into January, the accelerator was cooled to its operating temperature of -271°C. The so-called electron injector and first section of the main accelerator then went into operation, comprising altogether 18 of 98 total accelerator modules. Within this section, the electron bunches were both accelerated and compressed three times, down to 10 micrometres (a thousandth of a millimetre). Finally, the team placed the third section of the accelerator into operation. Currently, the electrons reach an energy of 12 gigaelectronvolts (GeV), and in regular operation, an energy of up to 17.5 GeV is planned.

    “The energy and other properties of the electron bunches are already within the range where they will be during first user operation”, says DESY physicist Winfried Decking, who leads the commissioning of the European XFEL accelerator.

    The coordination of the unique components of the accelerator and the control of the electron beam will now be intensively tested before the accelerated electrons are allowed into the following section: the up to 210 m long special magnetic structures called undulators. There, the ultrabright X-ray laser flashes will be generated. Scientific experiments should begin this fall.

    The superconducting particle accelerator of the European XFEL was built over the last seven years through an international consortium, under the leadership of DESY, composed of the following research institutes: CEA and CNRS in France; INFN in Italy; IFJ-PAN, NCBJ, and the Wrocław University of Technology in Poland; the Budker Institute, Institute for High Energy Physics, Institute for Nuclear Research, and NIIEFA in Russia; CIEMAT and Universidad Politécnica de Madrid in Spain; the Manne Siegbahn Laboratory, Stockholm University, and Uppsala University in Sweden; and the Paul Scherrer Institute in Switzerland.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 3:16 pm on April 18, 2017 Permalink | Reply
    Tags: Centre for Structural Systems Biology (CSSB), DESY, Electron cryo-microscopes, German Research Council grants co-financing of five electron cryo-microscopes at CSSB   

    From DESY: “High-tech microscopes for infection research” 

    DESY
    DESY

    2017/04/18

    German Research Council grants co-financing of five electron cryo-microscopes at CSSB

    The German Research Council DFG has granted the Universität Hamburg co-financing for establishing a 15.6 million Euro electron cryo-microscopy facility in the new Centre for Structural Systems Biology (CSSB) on the DESY campus. The German Federal Government will provide 50 per cent of the overall financing and the city of Hamburg will provide the other 50 per cent. The CSSB is a joint initiative of ten research partners from Northern Germany, including DESY. CSSB devotes itself to infection biology and medicine by utilizing structural and molecular biology methods and imaging techniques in conjunction with systems biology approaches.

    The planned five electron cryo-microscopes will be funded as part of the German Research Council’s major research instrumentation program.

    1
    Typical electron cryo-microscope, this one at Northwestern University, Chicago, USA

    They will complement the research opportunities at DESY’s ultra-bright X-ray light sources.

    2
    View into the main accelerator tunnel of European XFEL, where 100 superconducting accelerator modules are being installed (Photo: Dirk Nölle, DESY)

    Both methods enable three-dimensional imaging of biological structures at the molecular level. With the new super microscopes, scientists plan to study the complex molecular structures and function of pathogens as well as their interactions with host cell components such as proteins and membranes. The insights gained from this research will contribute to the identification of critical steps in the infection process and to the development of novel intervention strategies.

    “The investment in the pioneering electron cryo-microscopy in Hamburg is of national importance,” emphasised Hamburg’s Senator for Science, Research and Equality, Katharina Fegebank. “Infection researchers from all over Germany will come to the Bahrenfeld campus to use the microscopes and to pursue their research at the ultra-bright DESY light sources.”

    Matthias Wilmanns, Scientific Director of CSSB, emphasized: “The establishment of a state-of-the-art electron cryo-microscopy research infrastructure is a key element in CSSB’s overall research concept. This facility will provide our scientist with the technology to expand our understanding of host-pathogen interactions and tackle some of the most demanding scientific challenges in infection biology.”

    The CSSB is a joint venture of ten academic partners: Universität Hamburg, the University Medical Center Hamburg-Eppendorf (UKE), the Bernhard Nocht Institute for Tropical Medicine (BNITM), the Research Center Borstel (FZB), the European Molecular Biology Laboratory (EMBL), Forschungszentrum Jülich (FZJ), the Hannover Medical School (MHH), the Heinrich Pette Institute, Leibniz Institute for Experimental Virology (HPI), the Helmholtz Centre for Infection Research (HZI), and DESY. The different CSSB research groups will investigate pathogens from all three organism groups: viruses, bacteria, and eukaryotic parasites.

    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 1:16 pm on March 5, 2017 Permalink | Reply
    Tags: , DESY, DORIS storage ring, Olympus collaboration, , , Positron-proton and electron-proton elastic scattering   

    From DESY: “OLYMPUS experiment publishes first results for proton puzzle” 

    DESY
    DESY

    2017/03/03

    1
    DESY scientist Uwe Schneekloth during construction of the OLYMPUS dectector within the big toroid coils of the experiment. In the background on the left one can see the DORIS beampipe connected to the target cell, on the right the time of flight chambers (photo: DESY/ H. Müller-Elsner).

    The international OLYMPUS Collaboration this week published their first results in the journal Physical Review Letters. In 2012, the OLYMPUS detector made measurements at the DORIS storage ring to study a problem observed in electron-proton scattering.

    DESY DORIS III
    DESY DORIS III

    “The publication marks the culmination of a seven year research project to resolve a puzzling discrepancy in measurements of the proton form factors: GE and GM, which describe the electric and magnetic charge distributions inside the proton,” says Douglas Hasell from the Massachusetts Institute of Technology (MIT) in Boston, who is the spokesperson for some 55 OLYMPUS scientists from 13 institutions.

    MIT Widget

    The experiment produced precise measurements of the ratio between positron-proton and electron-proton elastic scattering to investigate the role of two-photon exchange in electron-proton scattering.

    The form factors examined by the OLYMPUS group are determined by the distribution of the quarks inside the proton. Scientists have been measuring these form factors for the past 60 or so years; in the 1960s and 1970s, they were also carried out at the DESY accelerator. Measurements made at Jefferson Lab in the USA in the early 2000s revealed deviations from older experiments by studying the collisions of polarised electrons and protons.

    Jefferson Lab

    One possible explanation could be that in some collisions instead of just one photon, several photons are exchanged between the two particles. In order to test this hypothesis, the 50-tonne OLYMPUS detector was installed at the DORIS storage ring. Most of it came from the BLAST detector, which was used at MIT from 2002 to 2005, adapted for the DORIS storage ring that also had to be modified.

    The big advantage of this combination was that DORIS could alternate between high intensity beams of electrons and their antiparticles, positrons, incident on the protons in a hydrogen gas target. In multi-photon exchange, differences arise depending on whether the protons were struck with electrons or positrons. “Using DORIS, we were able to switch very rapidly between electron and positron operation, which considerably reduces the systematic error in the measurements,” explains Uwe Schneekloth, a researcher at DESY who is the deputy spokesperson for the collaboration. “Thanks to the amazing support of DESY’s accelerator team, which kept DORIS up and running over the Christmas break and even implemented the top-up mode of operation for DORIS, we were able to collect a large amount of valuable data over our short operating time in spite of some technical challenges.”

    Overall, the scientists collected data for just over three months. In the course of the subsequent analysis, the researchers found that two different processes contribute to the assumed exchange of two photons during a collision. Whereas the dominant process can be described very well in theoretical terms, the distinctly smaller effect still poses certain riddles. It is markedly weaker than previous, less precise experiments, led scientists to believe. The OLYMPUS results indicate that this so-called “hard two-photon exchange” can explain the discrepancy between the two form factors. Although they agree with a general description of the phenomenon, existing model-dependent calculations still need to be modified in order to describe it. “To achieve a more precise understanding of the process, it would be helpful to conduct similar experiments at higher collision energies and with substantially higher collision frequencies. However, at the moment there is no suitable tailor-made solution for this, as we had in the case of the OLYMPUS detector at DORIS,” explains Schneekloth.

    “The findings from OLYMPUS will lead to a marked advance in our understanding of the proton,” explains Joachim Mnich, Director for particle and astroparticle physics at DESY. “I would like to congratulate the OLYMPUS Collaboration, whose experiment has supplied the most accurate data on this effect that will be available for the foreseeable future.”

    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.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: