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  • richardmitnick 12:27 pm on April 9, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From BNL: “First NSLS-II X-Ray Images Hint at Science to Come” 

    Brookhaven Lab

    April 9, 2015
    Laura Mgrdichian


    In another “first” at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory, a group working at the Hard X-Ray Nanoprobe has taken the facility’s inaugural x-ray images. Their striking renderings of a monarch butterfly specimen demonstrate the synchrotron’s ability to generate extremely detailed images and foretell a future of exciting research.

    An X-ray image of the butterfly antennae (A), the mouth (B), and one of claws (C). The imaged regions are indicated in the optical microgram in the center.

    “The staff scientists at the HXN beamline immensely enjoyed producing these amazingly sharp images,” said HXN group leader Yong Chu. “Even non-scientists can appreciate their superb quality, particularly when comparing them with a typical x-ray taken at a hospital. Their spectacular sharpness is due to the world-leading brightness of NSLS-II.”

    He continued, “This is a first step toward our ultimate goal of achieving x-ray images with details at the one-nanometer level and serves as a preview of the many exciting scientific results that will soon be discovered at HXN and NSLS-II’s many other beamlines.”

    The images were taken as part of a system check of the HXN beamline at NSLS-II, a U.S. Department of Energy Office of Science User Facility. After the beamline components and optics were aligned, monochromatic x-rays were sent from the first optical enclosure to the experimental station. At that point, the images were taken using a high-resolution charge-coupled device (CCD) camera with an optically coupled scintillation screen, which is a typical setup for x-ray imaging. During the test, the HXN group used an imaging resolution of 1.5 microns (millionths of a meter) per pixel.

    The test images were produced using x-rays that were only one-thousandth of the maximum power of NSLS-II. The butterfly sample was positioned 63 meters away from the x-ray source, and the CCD camera was placed 160 millimeters away from the sample. This camera-to-sample distance was chosen to yield images with the optimal contrast using a method called in-line phase-contrast imaging. Because the butterfly was much larger than the field of view of the camera, different parts of the specimen were imaged separately. Those images were then stitched together to construct a broader view.

    “The images show amazing contrast, as if they were hand-drawn by an artist,” said Hanfei Yan, one of the HXN beamline scientists.

    “Even at this modest imaging resolution of 1.5 microns, the collected images exhibit many interesting features of the insect that are not obvious to the public, such as the internal structure of the butterfly’s mouth, or proboscis,” said Sebastian Kalbfleisch, a member of the HXN beamline team. “The images also show elaborate semi-periodic joint structure in the antenna, which allow a butterfly to move its feelers freely in all directions.”

    Wah-Keat Lee, who is leading development of the NSLS-II Full-Field X-ray Imaging (FXI) beamline, added, “These superb images speak for themselves as to why NSLS-II is an ideal synchrotron for x-ray imaging.”

    Each image took five seconds to generate because only one-thousandth of the full power of NSLS-II was used. This means that, at the maximum storage-ring current of 500 milliamps, scientists will be able to perform monochromatic beam x-ray imaging with a five-millisecond exposure time.

    This month, Chu said, the HXN team will commission a one-of-kind x-ray microscope, equipped with novel x-ray lenses called multilayer Laue lenses, both of which are developed at NSLS-II. This unique instrument will produce images with a resolution equivalent to ten thousand times smaller than a human hair, and they will help him and his group reveal structural details in their samples, including elemental composition, crystalline ordering, and chemical states.

    See the full article here.

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

  • richardmitnick 8:58 am on April 9, 2015 Permalink | Reply
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    From XFEL: “European XFEL scientists look deep into the atom” 

    XFEL bloc

    European XFEL

    09 April 2015
    No Writer Credit

    Digging into the “Giant Resonance”, scientists find hints of new quantum physics

    A cooperation between theoretical and experimental physicists has uncovered previously unknown quantum states inside atoms. The results, described in a paper published today in the journal Nature Communications, allow a better understanding of some aspects of electron behaviour in atoms, which in turn could lead to better insights into technologically relevant materials.

    In this study, scientists from European XFEL and the Center for Free Electron Laser Science (CFEL) at DESY examined the unknown quantum states in atoms of the noble gas xenon using DESY’s X-ray laser FLASH.

    XFEL Campus


    The bright X-ray light of free-electron lasers such as FLASH and the European XFEL allowed the scientists to observe these states for the first time. (CFEL is a joint venture between DESY, the University of Hamburg, and the Max Planck Society.)

    Atoms can develop an electrical charge by losing or gaining one or more electrons. This process, called ionization, was thought to be fairly simple. As an electron departs, it can briefly “hang” between the different locations of electrons in the atom, also called “shells”. In the world of quantum mechanics, this brief pause—lasting less than a femtosecond, or a quadrillionth of a second—is enough to be measured as what is called a “resonance”.

    “In a resonance, the electrons are ‘talking’ to each other”, says Michael Meyer, a leading scientist at European XFEL. This conversation of sorts can be picked up on a spectrograph, and, in most atoms, it shows up in a very narrow energy range.

    Yet for the past half century, scientists also have noted a strange resonance in atoms of the noble gas xenon and some rare earth elements. In contrast to other resonances, it covers a very broad energy range. This became known as the “giant dipole resonance”. “There were no good tools to investigate the giant dipole resonance more deeply”, says Meyer. “But extreme-ultraviolet and X-ray FELs present an opportunity to re-examine xenon’s strange property.” Such facilities have the possibility of studying nonlinear processes, or phenomena that are not a direct result of a single interaction—in the case of photoionization the disappearance of one photon, with its energy being transferred to the electron that can thus escape the atom. The extraordinary intensity of FELs makes non-linear processes observable—in this case, a process whereby two photons disappear, simultaneously transferring their energy to the escaping electron.

    Graphical representation of a 4d electron orbital in atomic xenon. Antonia Karamatskou / DESY

    This has become evident when Tommaso Mazza, a scientist in Meyer’s group at European XFEL, and others investigated the ionization of xenon atoms under intense FEL radiation at DESY’s FLASH. In parallel, DESY scientist Robin Santra, the leader of the CFEL theory group, and a student in his group, Antonia Karamatskou, thought there was something more to the giant dipole resonance. They worked off of a forty-year old suggestion that had been largely ignored: that xenon actually had not one but two resonances, and that earlier spectrographic techniques could not distinguish between them. In contrast, X-ray FELs can target very specific energies in the electronic structure of the atom using just two individual particles of light, enabling scientists to see both resonances more clearly.

    Santra and Karamatskou made calculations describing the energies of the resonances. The data from the experiments performed at FLASH by Tommaso Mazza and others match Santra’s and Karamatskou’s predictions. This is the first evidence of the giant dipole resonance being composed of two other resonances.

    Both Santra and Meyer think that there is far more to the behaviour of electrons within atoms in general than has been previously understood. The result point to not yet fully understood aspects of how atoms function.

    “We don’t even yet understand why there might be a second resonance”, Santra says. “Many people think simple atomic physics is figured out, but as this collaboration has shown, there is a lot of hidden stuff out there!”

    Also, the experiment has shown that FELs can be highly sophisticated tools for studying quantum physics. Santra says he expects the European XFEL, which is due to open to users in 2017, to expand these possibilities even further.

    The research collaboration between Meyer and Santra was initiated and supported by the Collaborative Research Center at the University of Hamburg, SFB 925.

    “Sensitivity of nonlinear photoionization to resonance substructure in collective excitation”; T. Mazza, A. Karamatskou, M. Ilchen, S. Bakhtiarzadeh, A.J. Rafipoor, P. O’Keeffe, T.J. Kelly, N. Walsh, J.T. Costello, M. Meyer & R. Santra; Nature Communications, 2015; DOI: 10.1038/ncomms7799

    See the full article here.

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    XFEL Campus

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

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

  • richardmitnick 8:49 am on April 2, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From SLAC: “Scientists Track Ultrafast Creation of a Catalyst with X-ray Laser” 

    SLAC Lab

    April 1, 2015

    Chemical Transformations Driven by Light Provide Key Insight to Steps in Solar-energy Conversion

    This artistic rendering shows an iron-centered molecule that is severed by laser light (upper left). Within hundreds of femtoseconds, or quadrillionths of a second, a molecule of ethanol from a solvent rushes in (bottom right) to bond with the iron-centered molecule. (SLAC National Accelerator Laboratory)

    An international team has for the first time precisely tracked the surprisingly rapid process by which light rearranges the outermost electrons of a metal compound and turns it into an active catalyst – a substance that promotes chemical reactions.

    The results, published April 1 in Nature, could help in the effort to develop novel catalysts to efficiently produce fuel using sunlight. The research was performed with an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory.

    “We were able to determine how light rearranges the outermost electrons of the compound on timescales down to a few hundred femtoseconds, or quadrillionths of a second,” said Philippe Wernet, a scientist at Helmholtz-Zentrum Berlin for Materials and Energy who led the experiment.

    Researchers hope that learning these details will allow them to develop rules for predicting and controlling the short-lived early steps in important reactions, including the ones plants use to turn sunlight and water into fuel during photosynthesis. Scientists are seeking to replicate these natural processes to produce hydrogen fuel from sunlight and water, for example, and to master the chemistry required to produce other renewable fuels.

    “The eventual goal is to design chemical reactions that behave exactly the way you want them to,” Wernet said.

    In the experiment at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the scientists studied a yellowish fluid called iron pentacarbonyl, which consists of carbon monoxide “spurs” surrounding a central iron atom. It is a basic building block for more complex compounds and also provides a simple model for studying light-induced chemical reactions.

    SLAC LCLS Inside

    Researchers had known that exposing this iron compound to light can cleave off one of the five carbon monoxide spurs, causing the molecule’s remaining electrons to rearrange. The arrangement of the outermost electrons determines the molecule’s reactivity – including whether it might make a good catalyst – and also informs how reactions unfold.

    What wasn’t well understood was just how quickly this light-triggered transformation occurs and which short-lived intermediate states the molecule goes through on its way to becoming a stable product.

    At LCLS, the scientists struck a thin stream of the iron compound, which was mixed into an ethanol solvent, with pulses of optical laser light to break up the iron-centered molecules. Just hundreds of femtoseconds later, an ultrabright X-ray pulse probed the molecules’ transformation, which was recorded with sensitive detectors.

    By varying the arrival time of the X-ray pulses, they tracked the rearrangements of the outermost electrons during the molecular transformations.

    Roughly half of the severed molecules enter a chemically reactive state in which their outermost electrons are prone to binding other molecules. As a consequence, they either reconnect with the severed part or bond with an ethanol molecule to form a new compound. In other cases the outermost electrons in the molecule stabilize themselves in a configuration that makes the molecule non-reactive. All of these changes were observed within the time it takes light to travel a few thousandths of an inch.

    “To see this happen so quickly was extremely surprising,” Wernet said.

    Several years’ worth of data analysis and theoretical work were integral to the study, he said. The next step is to move on from model compounds to LCLS studies of the actual molecules used to make solar fuels.

    “This was a really exciting experiment, as it was the first time we used the LCLS to study chemistry in a liquid compound,” said Josh Turner, a SLAC staff scientist who participated in the experiment. “The LCLS is unique in the world in its ability to resolve these types of ultrafast processes in the right energy range for this compound.”

    SLAC’s Kelly Gaffney, a chemist who contributed expertise in how the changing arrangement of electrons steered the chemical reactions, said, “This work helps set the stage for future studies at LCLS and shows how cooperation across different research areas at SLAC enables broader and better science.”

    In addition to researchers from Helmholtz-Zentrum Berlin for Materials and Energy and LCLS, other scientists who assisted in the study were from: SLAC’s Stanford Synchrotron Radiation Lightsource; the SLAC and Stanford PULSE Institute; University of Potsdam, Max Planck Institute for Biophysical Chemistry, Goettingen University and DESY lab in Germany; Stockholm University and MAX-lab in in Sweden; Utrecht University in the Netherlands; Paul Scherrer Institute in Switzerland; and the University of Pennsylvania.

    This work was supported by the Volkswagen Foundation, the Swedish Research Council, the Carl Tryggers Foundation, the Magnus Bergvall Foundation, Collaborative Research Centers of the German Science Foundation and the Helmholtz Virtual Institute “Dynamic Pathways in Multidimensional Landscapes,” and the U.S. Department of Energy Office of Science.

    See the full article here.

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    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.

  • richardmitnick 2:23 pm on March 27, 2015 Permalink | Reply
    Tags: China Academy of Engineering and Physics, , X-ray Technology   

    From XFEL: “Major Chinese research centre signs collaboration agreement” 

    XFEL bloc

    European XFEL

    Officials at the signing ceremony at the Consulate of the People’s Republic of China in Hamburg. Front row, from left: European XFEL Administrative Director Claudia Burger, CAEP Vice Director Liu Cangli, European XFEL Managing Director Massimo Altarelli. Back row, from left: Consul-General of the People’s Republic of China Yang Huiqun, Counsellor Zhao Qinhua from the Embassy of the People’s Republic of China in Germany. European XFEL

    On 26 March, representatives of the China Academy of Engineering Physics (CAEP) signed a framework collaboration agreement with European XFEL at the Consulate of the People’s Republic of China in Hamburg.

    The agreement formalizes CAEP’s future involvement in the X-ray free-electron laser facility and is intended to provide the basis for future exchange of staff and students and the development of instrumentation for European XFEL. CAEP is a major research centre that operates 12 research institutes and 15 national laboratories across China. In many scientific institutes across China, there is a rising interest in doing research with X-ray free-electron lasers, and CAEP looks to spearhead Chinese involvement with these facilities.

    “As time goes by, I hope we will be able to estimate material properties with ever decreasing uncertainties. One of the significant issues here might be the poor understanding of the phenomena at meso-scale”, says CAEP Vice Director Liu Cangli. “We see a powerful XFEL, such as this one under construction in Hamburg, as being the most important tool in terms of taking on this very challenging task.”

    European XFEL Managing Director Massimo Altarelli says: “We are very happy about the involvement of the CAEP, and we greatly appreciate their interest in the European XFEL. Their expertise across many areas of physics and engineering will be of considerable value to the research at this facility.”

    See the full article here.

    Please help promote STEM in your local schools.

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    XFEL Campus

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

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

  • richardmitnick 12:03 pm on March 24, 2015 Permalink | Reply
    Tags: , , Warm Dense Matter, X-ray Technology   

    From SLAC: “Experiment Provides the Best Look Yet at ‘Warm Dense Matter’ at Cores of Giant Planets” 

    SLAC Lab

    March 23, 2015

    Shock Wave Experiment at SLAC’s X-ray Laser Tracks Formation of a Mysterious Type of Matter

    In an experiment at the Department of Energy’s SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as it transitions into a superhot, highly compressed concoction known as “warm dense matter.”

    This illustration shows a cutaway view of Jupiter, which is believed to contain “warm dense matter” at its core. A study at SLAC’s Linac Coherent Light Source X-ray laser has provided the most detailed measurements yet of a material’s temperature and compression as it transitions into this exotic state of matter. (SLAC National Accelerator Laboratory)

    Warm dense matter is the stuff believed to be at the cores of giant gas planets in our solar system and some of the newly observed “exoplanets” that orbit distant suns, which can be many times more massive than Jupiter. Their otherworldly properties, which stretch our understanding of planetary formation, have excited new interest in studies of this exotic state of matter.

    The results of the SLAC study, published March 23 in Nature Photonics, could also lead to a greater understanding of how to produce and control nuclear fusion, which scientists hope to harness as a new source of energy.

    “The heating and compression of warm dense matter has never been measured before in a laboratory with such precise timing,” says Siegfried Glenzer, a distinguished staff scientist who is part of the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. “We have shown the detailed steps of how a solid hit by powerful lasers becomes a compressed solid and a dense plasma at the same time. This is a step on the path toward creating fusion in the lab.”

    This video describes how scientists at SLAC created and precisely measured the temperature and compression in “warm dense matter,” an exotic state that is believed to exist at the core of giant planets like Jupiter. (SLAC National Accelerator Laboratory)

    A team led by Glenzer used laser light to compress ultrathin aluminum foil samples to a pressure more than 4,500 times higher than the deepest ocean depths and superheat it to 20,000 kelvins – about four times hotter than the surface of the sun. SLAC’s Linac Coherent Light Source X-ray laser, a DOE Office of Science User Facility, then precisely measured the foil’s properties as it transformed into warm dense matter and then into a plasma – a very hot gas of electrons and supercharged atoms.

    SLAC LCLS Inside

    Warm dense matter remains largely mysterious because it is difficult to create and study in a laboratory, can exhibit properties of several types of matter and occupies a middle ground between solid and plasma. Our own sun is an example of a self-sustaining plasma, and plasmas have also been harnessed in some TV displays.

    While warm dense matter is believed to exist in a stable state at the heart of giant planets, in a laboratory it lasts just billionths of a second. Scientists have relied largely on computer simulations, driven by scientific theories, to help explain how a solid, when shocked with powerful lasers, transforms into a plasma.

    LCLS, with its complement of high-power lasers, is uniquely suited to creating and studying matter at the extremes. Its ultrabright X-ray pulses are measured in femtoseconds, or quadrillionths of a second, so it works like an ultra-high-speed X-ray camera to illuminate and record the properties of the most fleeting phenomena in atomic-scale detail.

    In this experiment, researchers used a high-power optical laser at LCLS’s Matter in Extreme Conditions experimental station to fire separate beams of green laser light simultaneously at both sides of coated, ultrathin aluminum foil samples, each just half the width of an average human hair. The lasers produced shock waves in the material that converged to create extreme temperatures and pressures.

    Scientists prepare for an experiment at SLAC’s Matter in Extreme Conditions (MEC) station, part of the Linac Coherent Light Source X-ray laser. They used this MEC station to create and measure the properties of ultrathin sheets of superheated aluminum as it transitioned into warm dense matter, an exotic state of matter.(SLAC National Accelerator Laboratory)

    Researchers struck the samples with X-rays just nanoseconds later, and varied the arrival time of the X-rays to essentially make a series of snapshots of warm dense matter formation. The team used a technique known as small angle X-ray scattering to measure the internal structure of the material, capturing its brief transition into the warm dense state.

    “This early work with aluminum is a first stepping stone toward other problems we really need to solve,” Glenzer said, such as how hydrogen behaves under similar conditions. Hydrogen, which makes up about 75 percent of the visible mass of the universe, plays a central role in fusion, the process that powers stars. A better understanding of how hydrogen transitions into warm dense matter could help settle debates over conflicting theories on this transition and help unlock the secrets of fusion energy.

    “I think LCLS can help to resolve the hydrogen ‘controversy,’ in upcoming experiments,” Glenzer said.

    Participants in the research included scientists at SLAC, University of California Berkeley, Lawrence Livermore National Laboratory and General Atomics; QuantumWise A/S in Denmark; AWE plc, University of Warwick and University of Oxford in the U.K.; and the Max Planck Institute for the Physics of Complex Systems, Institute for Optics and Quantum Electronics, Friedrich-Schiller-University and GSI Helmholtz Center for Heavy Ion Research in Germany.

    The work was supported by the DOE Office of Science, Fusion Energy Science; the DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division; Lawrence Livermore National Laboratory; a Laboratory Directed Research and Development grant; and the Peter-Paul-Ewald Fellowship of the VolkswagenStiftung.

    See the full article here.

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    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.

  • richardmitnick 8:41 am on March 19, 2015 Permalink | Reply
    Tags: , , , , , X-ray Technology   

    From SLAC: “Scientists Watch Quantum Dots ‘Breathe’ in Response to Stress” 

    SLAC Lab

    March 18, 2015

    Nanocrystal Study at SLAC’s X-ray Laser Could Aid in the Design of New Materials

    In this illustration, intense X-rays produced at SLAC’s Linac Coherent Light Source strike nanocrystals of a semiconductor material. Scientists used the X-rays to study an ultrafast “breathing” response in the crystals induced quadrillionths of a second earlier by laser light. (SLAC National Accelerator Laboratory)

    Researchers at the Department of Energy’s SLAC National Accelerator Laboratory watched nanoscale semiconductor crystals expand and shrink in response to powerful pulses of laser light. This ultrafast “breathing” provides new insight about how such tiny structures change shape as they start to melt – information that can help guide researchers in tailoring their use for a range of applications.

    In the experiment using SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, a DOE Office of Science User Facility, researchers first exposed the nanocrystals to a burst of laser light, followed closely by an ultrabright X-ray pulse that recorded the resulting structural changes in atomic-scale detail at the onset of melting.

    SLAC LCLS Inside

    “This is the first time we could measure the details of how these ultrasmall materials react when strained to their limits,” said Aaron Lindenberg, an assistant professor at SLAC and Stanford who led the experiment. The results were published March 12 in Nature Communications.

    Getting to Know Quantum Dots

    The crystals studied at SLAC are known as “quantum dots” because they display unique traits at the nanoscale that defy the classical physics governing their properties at larger scales. The crystals can be tuned by changing their size and shape to emit specific colors of light, for example.

    So scientists have worked to incorporate them in solar panels to make them more efficient and in computer displays to improve resolution while consuming less battery power. These materials have also been studied for potential use in batteries and fuel cells and for targeted drug delivery.

    Scientists have also discovered that these and other nanomaterials, which may contain just tens or hundreds of atoms, can be far more damage-resistant than larger bits of the same materials because they exhibit a more perfect crystal structure at the tiniest scales. This property could prove useful in battery components, for example, as smaller particles may be able to withstand more charging cycles than larger ones before degrading.

    A Surprise in the ‘Breathing’ of Tiny Spheres and Nanowires

    In the LCLS experiment, researchers studied spheres and nanowires made of cadmium sulfide and cadmium selenide that were just 3 to 5 nanometers, or billionths of a meter, across. The nanowires were up to 25 nanometers long. By comparison, amino acids – the building blocks of proteins – are about 1 nanometer in length, and individual atoms are measured in tenths of nanometers.

    By examining the nanocrystals from many different angles with X-ray pulses, researchers reconstructed how they change shape when hit with an optical laser pulse. They were surprised to see the spheres and nanowires expand in width by about 1 percent and then quickly contract within femtoseconds, or quadrillionths of a second. They also found that the nanowires don’t expand in length, and showed that the way the crystals respond to strain was coupled to how their structure melts.

    In an earlier, separate study, another team of researchers had used LCLS to explore the response of larger gold particles on longer timescales.

    “In the future, we want to extend these experiments to more complex and technologically relevant nanostructures, and also to enable X-ray exploration of nanoscale devices while they are operating,” Lindenberg said. “Knowing how materials change under strain can be used together with simulations to design new materials with novel properties.”

    Participating researchers were from SLAC, Stanford and two of their joint institutes, the Stanford Institute for Materials and Energy Sciences (SIMES) and Stanford PULSE Institute; University of California, Berkeley; University of Duisburg-Essen in Germany; and Argonne National Laboratory. The work was supported by the DOE Office of Science and the German Research Council.

    See the full article here.

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    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.

  • richardmitnick 10:55 am on March 18, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From ars technica: “Shining an X-Ray torch on quantum gravity” 

    Ars Technica
    ars technica

    Mar 17, 2015
    Chris Lee

    This free electron laser could eventually provide a test of quantum gravity. BNL

    Quantum mechanics has been successful beyond the wildest dreams of its founders. The lives and times of atoms, governed by quantum mechanics, play out before us on the grand stage of space and time. And the stage is an integral part of the show, bending and warping around the actors according to the rules of general relativity. The actors—atoms and molecules—respond to this shifting stage, but they have no influence on how it warps and flows around them.

    This is puzzling to us. Why is it such a one directional thing: general relativity influences quantum mechanics, but quantum mechanics has no influence on general relativity? It’s a puzzle that is born of human expectation rather than evidence. We expect that, since quantum mechanics is punctuated by sharp jumps, somehow space and time should do the same.

    There’s also the expectation that, if space and time acted a bit more quantum-ish, then the equations of general relativity would be better behaved. In general relativity, it is possible to bend space and time infinitely sharply. This is something we simply cannot understand: what would infinitely bent space look like? To most physicists, it looks like something that cannot actually be real, indicating a problem with the theory. Might this be where the actors influence the stage?

    Quantum mechanics and relativity on the clock

    To try and catch the actors modifying the stage requires the most precise experiments ever devised. Nothing we have so far will get us close, so a new idea from a pair of German physicists is very welcome. They focus on what’s perhaps the most promising avenue for detecting quantum influences on space-time: time-dilation experiments. Modern clocks rely on the quantum nature of atoms to measure time. And the flow of time depends on relative speed and gravitational acceleration. Hence, we can test general relativity, special relativity, and quantum mechanics all in the same experiment.

    To get an idea of how this works, let’s take a look at the traditional atomic clock. In an atomic clock, we carefully prepare some atoms in a predefined superposition state: that is the atom is prepared such that it has a fifty percent chance of being in state A, and a fifty percent chance of being in state B. As time passes, the environment around the atom forces the superposition state to change. At some later point, it will have a seventy five percent chance of being in state A; even later, it will certainly be in state A. Keep on going, however, and the chance of being in state A starts to shrink, and it continues to do so until the atom is certainly in state B. Provided that the atom is undisturbed, these oscillations will continue.

    These periodic oscillations provide the perfect ticking clock. We simply define the period of an oscillation to be our base unit of time. To couple this to general relativity measurements is, in principle, rather simple. Build two clocks and place them beside each other. At a certain moment, we start counting ticks from both clocks. When one clock reaches a thousand (for instance), we compare the number of ticks from the two clocks. If we have done our job right, both clocks should have reached a thousand ticks.

    If we shoot one into space, however, and perform the same experiment, and relativity demands that the clock in orbit record more ticks than the clock on Earth. The way we record the passing of time is by a phenomena that is purely quantum in nature, while the passing of time is modified by gravity. These experiments work really well. But at present, they are not sensitive enough to detect any deviation from either quantum mechanics or general relativity.

    Going nuclear

    That’s where the new ideas come in. The researchers propose, essentially, to create something similar to an atomic clock, but instead of tracking the oscillation atomic states, they want to track nuclear states. Usually, when I discuss atoms, I ignore the nucleus entirely. Yes, it is there, but I only really care about the influence the nucleus has on the energetic states of the electrons that surround it. However, in one key way the nucleus is just like the electron cloud that surrounds it: it has its own set of energetic states. It is possible to excite nuclear states (using X-Ray radiation) and, afterwards, they will return the ground state by emitting an X-Ray.

    So let’s imagine that we have a crystal of silver sitting on the surface of the Earth. The silver atoms all experience a slightly different flow of time because the atoms at the top of the crystal are further away from the center of the Earth compared to the atoms at the bottom of the crystal.

    To kick things off, we send in a single X-Ray photon, which is absorbed by the crystal. This is where the awesomeness of quantum mechanics puts on sunglasses and starts dancing. We don’t know which silver atom absorbed the photon, so we have to consider that all of them absorbed a tiny fraction of the photon. This shared absorption now means that all of the silver atoms enter a superposition state of having absorbed and not absorbed a photon. This superposition state changes with time, just like in an atomic clock.

    In the absence of an outside environment, all the silver atoms will change in lockstep. And when the photon is re-emitted from the crystal, all the atoms will contribute to that emission. So each atom behaves as if it is emitting a partial photon. These photons add together, and a single photon flies off in the same direction as the absorbed photon had been traveling. Essentially because all the atoms are in lockstep, the charge oscillations that emit the photon add up in phase only in the direction that the absorbed photon was flying.

    Gravity, though, causes the atoms to fall out of lockstep. So when the time comes to emit, the charge oscillations are all slightly out of phase with each other. But they are not random: those at the top of the crystal are just slightly ahead of those at the bottom of the crystal. As a result, the direction for which the individual contributions add up in phase is not in the same direction as the flight path of the absorbed photon, but at a very slight angle.

    How big is this angle? That depends on the size of the crystal and how long it takes the environment to randomize the emission process. For a crystal of silver atoms that is less than 1mm thick, the angle could be as large as 100 micro-degrees, which is small but probably measurable.
    Spinning crystals

    That, however, is only the beginning of a seam of clever. If the crystal is placed on the outside of a cylinder and rotated during the experiment, then the top atoms of the crystal are moving faster than the bottom, meaning that the time-dilation experienced at the top of the crystal is greater than that at the bottom. This has exactly the same effect as placing the crystal in a gravitational field, but now the strength of that field is governed by the rate of rotation.

    In any case, by spinning a 10mm diameter cylinder very fast (70,000 revolutions per second), the angular deflection is vastly increased. For silver, for instance, it reaches 90 degrees. With such a large signal, even smaller deviations from the predictions of general relativity should be detectable in the lab. Importantly, these deviations happen on very small length scales, where we would normally start thinking about quantum effects in matter. Experiments like these may even be sensitive enough to see the influence of quantum mechanics on space and time.

    A physical implementation of this experiment will be challenging but not impossible. The biggest issue is probably the X-Ray source and doing single photon experiments in the X-Ray regime. Following that, the crystals need to be extremely pure, and something called a coherent state needs to be created within them. This is certainly not trivial. Given that it took atomic physicists a long time to achieve this for electronic transitions, I think it will take a lot more work to make it happen at X-Ray frequencies.

    On the upside free electron lasers have come a very long way, and they have much better control over beam intensities and stability. This is, hopefully, the sort of challenge that beam-line scientists live for.

    See the full article here.

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    Ars Technica was founded in 1998 when Founder & Editor-in-Chief Ken Fisher announced his plans for starting a publication devoted to technology that would cater to what he called “alpha geeks”: technologists and IT professionals. Ken’s vision was to build a publication with a simple editorial mission: be “technically savvy, up-to-date, and more fun” than what was currently popular in the space. In the ensuing years, with formidable contributions by a unique editorial staff, Ars Technica became a trusted source for technology news, tech policy analysis, breakdowns of the latest scientific advancements, gadget reviews, software, hardware, and nearly everything else found in between layers of silicon.

    Ars Technica innovates by listening to its core readership. Readers have come to demand devotedness to accuracy and integrity, flanked by a willingness to leave each day’s meaningless, click-bait fodder by the wayside. The result is something unique: the unparalleled marriage of breadth and depth in technology journalism. By 2001, Ars Technica was regularly producing news reports, op-eds, and the like, but the company stood out from the competition by regularly providing long thought-pieces and in-depth explainers.

    And thanks to its readership, Ars Technica also accomplished a number of industry leading moves. In 2001, Ars launched a digital subscription service when such things were non-existent for digital media. Ars was also the first IT publication to begin covering the resurgence of Apple, and the first to draw analytical and cultural ties between the world of high technology and gaming. Ars was also first to begin selling its long form content in digitally distributable forms, such as PDFs and eventually eBooks (again, starting in 2001).

  • richardmitnick 9:20 am on March 13, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From DESY: “Molecules perform endless cartwheels” 


    No Writer Credit

    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.

    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.

    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.

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    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 3:00 am on March 12, 2015 Permalink | Reply
    Tags: , , , X-ray Technology   

    From New Scientist: “HIV’s hiding places at last revealed by simple scan” 


    New Scientist

    09 March 2015
    Clare Wilson

    (Image: medicalrf.com/Getty)

    It’s like using heat cameras to catch criminals on the run, but it finds HIV instead. A novel scanning technique is enabling researchers to pinpoint where in the body HIV is lurking.

    “This could really help with the research for a functional cure,” says Alan Winston of Imperial College London, who was not involved in the study.

    Today’s potent drug treatments can eradicate HIV from the blood, but the virus must survive elsewhere in the body, because it returns when people stop taking these drugs.

    It has been assumed that the virus hides out in immune cells at various “sanctuary sites”, either replicating very slowly or becoming completely dormant. Supporting this, biopsies reveal the virus in sites such as patches of immune tissue in the gut.

    Sanctuary sites

    One strategy to eradicate HIV completely might be to somehow wake up the hiding virus and then kill it. Research into this “kick and kill” strategy is ongoing, but little is known about which sanctuary sites are the most important, what the virus is doing there and whether existing drugs can reach the sites.

    Francois Villinger of Emory University in Atlanta and colleagues wondered if a PET scanning approach, which is also used to show the spread of cancer, could reveal the location of the virus. This idea was prompted by the discovery of an antibody that binds strongly to SIV, the monkey version of HIV.

    To test the idea, the team injected radioactive antibodies into three monkeys with SIV that were being treated with antiviral drugs. PET scanning, which can detect the location of radiation sources within the body, revealed the viral protein, called gp120, in a range of sites including the nose, lungs, gut, genitals and lymph nodes in the armpits and groin. The antibody could not get into the brain, however, which is thought to be another sanctuary site.

    The scans were not detailed enough to reveal which specific cells the virus protein was in, but tests after the monkeys were killed confirmed that the virus was present in the immune cells of the areas identified by the scan.

    Kick and kill

    Although the technique won’t show up a virus that is completely dormant, just being able to see where there is low viral replication is a major advance, says Winston. “It’s the first paper that has allowed us to visualise viral reservoirs.”

    The next step would be to develop antibodies that can recognise the gp120 protein made by the human strain of the virus. Scans made using these could aid researchers working on kick-and-kill strategies, and help investigate the rare cases where people seem to have been cured of HIV.

    This has been claimed for a handful of people who were given bone marrow transplants from donors whose immune cells are resistant to HIV, as well as for an infant who was given antiviral drugs straight after birth.

    Initially after that child – the so-called Mississippi baby – was taken off the drugs, there was no virus detectable in her blood, and her doctor claimed a cure. Unfortunately, after four years the virus returned and she had to restart drug treatment.

    The PET scanning technique could help in such cases, Villinger speculates, by revealing if the virus is present in sanctuary sites.

    See the full article here.

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  • richardmitnick 6:51 am on March 8, 2015 Permalink | Reply
    Tags: ETH Zurich, , X-ray Technology   

    From ETH Zurich: “An oscilloscope for MRI scanners” 

    ETH Zurich bloc

    ETH Zurich

    Anna Maltsev

    Skope co-founder Christoph Barmet demonstrates the Dynamic Field Camera in an MRI scanner. (Image: Skope)

    Take three driven physics wizards, an innovative business idea and lots of hard work, and what do you get? An ETH spin-off that could further advance both MRI research and medical diagnostics.

    “Actually, I really wanted to work in the insurance industry,” explains Christoph Barmet with a sheepish smile. Ten years, an ETH Silver Medal and a spin-off later, however, the 37-year old is now confident that his decision to focus on MRI technology instead of the insurance industry was the right one.

    MRI (magnetic resonance imaging) is defined as the form of magnetic resonance spectroscopy that produces cross-section images in any desired spatial plane, with excellent contrast particularly for tissue and internal organs in the human body. Based on MR images, accurate medical diagnosis and detailed exploration of individual body parts are possible. MRI is based on the fact that nuclei of hydrogen atoms within the human body can be excited by radio waves and as a result emit radio waves themselves. These waves are received by special coils, encoded with the help of magnetic fields and reconstructed into images using software.

    From students to entrepreneurs

    The former ETH student first got to know and love the technology while working on his master thesis. “In my thesis, I tried to make the heart vessels more visible through MRI. I found the technology so fascinating that I didn’t have to think twice when Professor Prüssmann offered me a doctoral dissertation in the MRI field,” recalls Barmet, who comes from Lucerne.

    At almost the same time that he finished, David Brunner and Bertram Wilm also completed their doctorates in MRI technology at ETH Zurich’s Institute for Biomedical Engineering. Barmet and Brunner both received an ETH Medal for their work. Beside their enthusiasm for MRI technology, a further passion united the three physics wizards: the dream of their own business. “In 2011, the time had come. Two years following our dissertation, our spin-off named Skope was born,” says Barmet, beaming. “We had long considered the product we wanted to produce and eventually decided on a measurement instrument to improve MRI images, dubbed Dynamic Field Camera.”


    More precise research results and early diagnosis

    In comparison, an MRI image acquired without the use of a Dynamic Field Camera and exhibiting some image artifacts (left) and a retrospectively corrected image using the new camera (right). (Image: Skope)

    This camera measures the encoding magnetic field dynamics present in the MR scanner with unprecedented accuracy and sensitivity, detecting encoding errors that are unavoidable even with the newest machines. These errors can be corrected either at the pre-emphasis level, in real time, or afterwards in the reconstruction of the data into images. Thus, more accurate, faster and more quantitative MRI images are possible.

    Meanwhile, the young entrepreneurs have also brought a second product, the Clip-on Camera, to market. It measures the dynamic magnetic fields during the actual MRI scan and allows a correction of the magnetic fields in real time; thereby perturbations are removed and the images turn more precise without involving additional signal post-processing.

    Potential users of this innovative device include primarily MRI researchers and manufacturers of MRI scanners. And despite the significant cost of about CHF 250,000 per device, the ETH graduates are pleased with sales so far. “Several research groups from around the world have bought our cameras, as well as Siemens, the largest manufacturer of MRI scanners. Philipps is currently testing it,” says Barmet. In the long run, the measurement devices will lead to more precise research results, and faster, more accurate medical diagnosis. For example, tumours can be detected earlier with the camera and blood flow measured more effectively than before. “If at some point the Dynamic Field Camera sensor technology were installed in every MRI scanner, it would mean faster, enhanced MRI diagnostics, and the realization of my dream” says Barmet.

    See the full article here.

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    ETH Zurich campus
    ETH Zurich is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zurich today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

    Twenty-one Nobel Laureates have studied, taught or conducted research at ETH Zurich, underlining the excellent reputation of the university.

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