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

    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 .

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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 1:45 pm on April 18, 2017 Permalink | Reply
    Tags: , , , Gabriella Carini, How do you catch femtosecond light?, , , , , , X-ray Technology   

    From SLAC: “How do you catch femtosecond light?” 


    SLAC Lab

    1
    Gabriella Carini
    Staff Scientist
    Joined SLAC: 2011
    Specialty: Developing detectors that capture light from X-ray sources
    Interviewed by: Amanda Solliday

    Gabriella Carini enjoys those little moments—after hours and hours of testing in clean rooms, labs and at X-ray beamlines—when she first sees an instrument work.

    She earned her PhD in electronic engineering at the University of Palermo in Italy and now heads the detectors department at the Linac Coherent Light Source (LCLS), the X-ray free-electron laser at SLAC.

    SLAC/LCLS

    Scientists from around the world use the laser to probe natural processes that occur in tiny slivers of time. To see on this timescale, they need a way to collect the light and convert it into data that can be examined and interpreted.

    It’s Carini’s job to make sure LCLS has the right detector equipment at hand to catch the “precious”, very intense laser pulses, which may last only a few femtoseconds.

    When the research heads in new directions, as it constantly does, this requires her to look for fresh technology and turn these ideas into reality.

    When did you begin working with detectors?

    I moved to the United States as a doctoral student. My professor at the time suggested I join a collaboration at Brookhaven National Laboratory, where I started developing gamma ray detectors to catch radioactive materials.

    Radioactive materials give off gamma rays as they decay, and gamma rays are the most energetic photons, or particles of light. The detectors I worked on were made from cadmium zinc telluride, which has very good stopping power for highly energetic photons. These detectors can identify radioactive isotopes for security—such as the movement of nuclear materials—and contamination control, but also gamma rays for medical and astrophysical observations.

    We had some medical projects going on at the time, too, with detectors that scan for radioactive tracers used to map tissues and organs with positron emission tomography.

    From gamma ray detectors, I then moved to X-rays, and I began working on the earliest detectors for LCLS.

    How do you explain your job to someone outside the X-ray science community?

    I say, “There are three ingredients for an experiment—the source, the sample and the detector.”

    You need a source of light that illuminates your sample, which is the problem you want to solve or investigate. To understand what is happening, you have to be able to see the signal produced by the light as it interacts with the sample. That’s where the detector comes in. For us, the detector is like the “eyes” of the experimental set-up.

    What do you like most about your work?

    2

    There’s always a way we can help researchers optimize their experiments, tweak some settings, do more analysis and correction.

    This is important because scientists are going to encounter a lot of different types of detectors if they work at various X-ray facilities.

    I like to have input from people who are running the experiments. Because I did experiments myself as a graduate student, I’m very sensitive to whether a system is user-friendly. If you don’t make something that researchers can take the best advantage of, then you didn’t do your job fully.

    And detectors are never perfect, no matter which one you buy or build.

    There are a lot of people who have to come together to make a detector system. It’s not one person’s work. It’s many, many people with lots of different expertise. You need to have lots of good interpersonal skills.

    What are some of the challenges of creating detectors for femtosecond science?

    In more traditional X-ray sources the photons arrive distributed over time, one after the other, but when you work with ultrafast laser pulses like the ones from LCLS, all your information about a sample arrives in a few femtoseconds. Your detector has to digest this entire signal at once, process the information and send it out before another pulse comes. This requires deep understanding of the detector physics and needs careful engineering. You need to optimize the whole signal chain from the sensor to the readout electronics to the data transmission.

    We also have mechanical challenges because we have to operate in very unusual conditions: intense optical lasers, injectors with gas and liquids, etc. In many cases we need to use special filters to protect the detectors from these sources of contamination.

    4
    And often, you work in vacuum. With “soft” or low-energy X-rays, they are absorbed very quickly in air. Your entire system has to be vacuum-compatible. With many of our substantial electronics, this requires some care.

    So there are lots of things to take into account. Those are just a few examples. It’s very complicated and can vary quite a bit from experiment to experiment.

    Is there a new project you are really excited about?

    All of LCLS-II—this fills my life! We’re coming up with new ideas and new technologies for SLAC’s next X-ray laser, which will have a higher firing rate—up to a million pulses per second. For me, this is a multidimensional puzzle. Every science case and every instrument has its own needs and we have to find a route through the many options and often-competing parameters to achieve our goals.

    X-ray free-electron lasers are a big driver for detector development. Ten years ago, no one would have talked about X-ray cameras delivering 10,000 pictures per second. The new X-ray lasers are really a game-changer in developing detectors for photon science, because they require detectors that are just not readily available.

    LCLS-II will be challenging, but it’s exciting. For me, it’s thinking about what we can do now for the very first day of operation. And while doing that, we need to keep pushing the limits of what we have to do next to take full advantage of our new machine.

    6

    SLAC LCLS-II

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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.
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  • richardmitnick 12:03 pm on April 17, 2017 Permalink | Reply
    Tags: , How X-rays Pushed Topological Matter Research Over the Top, X-ray Technology   

    From LBNL: “How X-rays Pushed Topological Matter Research Over the Top” 

    Berkeley Logo

    Berkeley Lab

    April 14, 2017
    Glenn Roberts Jr.
    geroberts@lbl.gov
    510-486-5582

    1
    Beamline 10.0.1 at Berkeley Lab’s Advanced Light Source is optimized for studies of topological properties in materials. (Credit: Roy Kaltschmidt/Berkeley Lab)

    LBNL/ALS

    While using X-rays generated by the Advanced Light Source (ALS), a synchrotron facility at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), to study a bismuth-containing thermoelectric material that can convert heat into electricity, physicist M. Zahid Hasan of Princeton University saw that something was interfering with the anticipated view of electrons’ behavior inside the material.

    Knowing how electrons move within this material was sought as a key to decipher how it worked, so this interference—which he and his team observed more than a decade ago during an experiment employing an X-ray-based technique dubbed ARPES (angle-resolved photoemission spectroscopy)—was a problem … at first.

    “Since 2004, I was involved with this research looking for a better understanding of bismuth-based thermoelectric materials, among other things,” said Hasan.

    Around 2007, after completing more X-ray experiments at the ALS and other synchrotrons, and after gaining some understanding of the theory related to his team’s observations, it would become clear to Hasan that this obstruction was actually a discovery: One that would spark a revolution in materials research that continues today, and that could eventually lead to new generations of electronics and quantum technologies.

    Topological matter research is now a flourishing field of research at the ALS, with several staff members devoted to supporting X-ray techniques that largely focus on its properties.

    “Since 2005, something on the surface was annoying me quite a bit,” said Hasan, a Princeton physics professor who in late 2016 became a visiting faculty member at Berkeley Lab’s Materials Sciences Division and a Visiting Miller Professor at UC Berkeley. “I could not get rid of the surface states.”

    Back at Princeton, Hasan struck up a conversation with a fellow physics professor, Duncan Haldane, and he also spoke with Charles Kane, a physics professor at the neighboring University of Pennsylvania, for their collective theoretical insight about the surface effects he was seeing in some bismuth-containing materials. “At that point I was not aware of the theoretical predictions.”

    They discussed theoretical work, some of it dating back several decades, that had explored bizarre and resilient “topological” states in which electrons could move about the surface of a thin material with next to no resistance—like in a traditional superconductor but with a different mechanism.

    The theoretical work provided little clue in how to find the effects in the materials exhibiting this phenomenon, though. So Hasan set out on a path that crossed into the fields of quantum theory, particle physics, and complex mathematics.

    “I had to translate all of the abstract math into these experiments,” he said. “It was like translating from a foreign language.”

    2
    In mathematics, topology is focused on properties that change step-wise, like the number of holes in the objects in the above image. Pioneering theories on topological phenomena in materials were key to the 2016 Nobel Prize in Physics, and were ultimately realized in X-ray experiments at Berkeley Lab’s Advanced Light Source and other similar light sources. Topology explains why electrical conductivity changes in thin-layer materials. (Credit: © Johan Jarnestad/The Royal Swedish Academy of Sciences)

    Flash forward to October 2016, and this time Haldane was describing his early theoretical work during a Nobel Prize press conference. Haldane shared the 2016 Nobel Prize in Physics with David Thouless of the University of Washington (a former postdoctoral researcher at Berkeley Lab), and J. Michael Kosterlitz of Brown University for their work in “theoretical discoveries of topological phase transitions and topological phases of matter.”

    Haldane had said at the time of the Nobel Prize announcement, “I put in the first paper that this is unlikely to be anything anyone could make.” His work, he said, was a “sleeper” that “sat around as an interesting toy model for a very long time—no one quite knew what to do with it.”

    What helped bring that “toy model” to life were later theories by Kane and collaborators, and innovative ARPES studies at the ALS and other synchrotrons that directly probed exotic topological states in some materials.

    Synchrotrons like the ALS have dozens of beamlines that produce focused X-rays and other types of light beams for a variety of experiments that explore the properties of exotic materials and other samples at tiny scales, and ARPES provides a window into materials’ electron properties.

    The Nobel Committee, in its supporting materials for the prize, had cited early experiments by Hasan’s team at the ALS on materials exhibiting topological insulator phases. A topological insulator acts like an electrical conductor on the surface and an insulator (with no electrical flow) inside.

    3
    Band structure of bismuth selenide, a topological insulator. The red areas represent surface states and the vertical space between the yellow areas is the bulk band gap. At lower right, a 3-D schematic of the cone-shaped surface band structure. The spin states (yellow arrows) indicate that electrons on the surface won’t backscatter from disorder and impurities in the material. (Credit: David Hsieh, Yuqi Xia, Andrew Wray/Princeton University)

    Zahid Hussain, division deputy at the ALS said, “Hasan is an exceptional scientist with a deep understanding of both theory and experiment. He is the reason this became experimentally visible. One experiment did that.”

    Hasan’s work provided an early demonstration of a 3-D topological insulator, for example.

    In these materials, the electron motion is relatively robust, and is immune to many types of impurities and deformities. Researchers have found examples of topological properties in materials even at room temperature.

    This is a critical advantage over so-called high-temperature superconductors, which must be chilled to extreme temperatures in order to achieve a nearly resistance-free flow of electrons.

    4
    A 3-D image of the surface band structure of bismuth telluride. (Credit: Yulin Chen, Z.-X. Shen/Stanford University)

    With topological materials, the electrons exhibit unique patterns in a property known as electron spin that is analogous to a compass needle pointing up or down, and this property can change based on the electron’s path and position in a material.

    One potential future application for the spin properties of electrons in topological materials is spintronics, an emerging field that seeks to control the spin on demand to transmit and store information, much like the zeroes and ones in traditional computer memory.

    Spin could also be harnessed as the information carriers in quantum computers, which could conceivably carry out exponentially more calculations of a certain type in a shorter time than conventional supercomputers.

    Jonathan Denlinger, a staff scientist in the Scientific Support Group at the ALS, said the breakthrough studies on materials with topological behavior led to a rapid shift in focus on materials’ surface properties. Researchers had historically been more interested in electrons within the “bulk,” or inside of materials.

    Hasan’s group used three ALS beamlines—MERLIN, 12.0.1, and 10.0.1—in pioneering ARPES studies of topological matter. Hasan was a co-leader on the proposal that led to the construction of MERLIN in the early 2000s.

    Denlinger, and fellow ALS staff scientists Alexei Fedorov and Sung-Kwan Mo, work at these ALS beamlines, which specialize in ARPES and a related variant called spin-resolved photoelectron spectroscopy. The techniques can provide detailed information about how electrons travel in materials and also about the electrons’ spin orientation.

    ARPES beamlines at the ALS remain in high demand for topological matter research. Fedorov said, “These days, almost every proposal submitted to our beamline in one way or another deals with topological matter.”

    The quest for discoveries of new topological matter at the ALS will also be boosted by a beamline known as MAESTRO (Microscopic and Electronic Structure Observatory) that opened to users last year and will help visualize exotic ordered structures formed in some topological materials.

    “ALS-U, a planned upgrade of the ALS, should improve and enhance topological matter studies using the ALS,” Mo said. “It will allow us to focus down to a very small spot,” which could reveal more detail in the electron behavior of topological matter.

    Improved X-ray performance could help identify some topological materials that were previously overlooked, and to better distinguish and classify their properties, Hasan said.

    Hasan’s early work in topological matter, including topological insulators, led him to the detection of a previously theorized massless particle known as the Weyl fermion in topological semimetals, and he is now devising a related experiment that he hopes will mimic the period of the early universe in which particles began to take on mass.

    Denlinger, Fedorov, and Mo are gearing up for more studies of topological matter, and are reaching out to possible collaborators across Berkeley Lab and the global scientific community.

    Nanoscale materials show a lot of promise for topological materials applications, and thermoelectrics—those same materials that can transfer heat to electricity and vice versa, and that led to the first realization of topological matter in X-ray experiments—should see performance gains in the short term thanks to the feverish pace of R&D in the field, Fedorov noted.

    Hasan, too, said he is excited about progress in the field. “We are in the middle of a topological revolution in physics, for sure,” he said.

    The Advanced Light Source (ALS) is a DOE Office of Science User Facility. Operation of ALS and this work is supported by the DOE Office of Science.

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  • richardmitnick 9:23 pm on April 11, 2017 Permalink | Reply
    Tags: , , , , , , , Theory Institute for Materials and Energy Spectroscopies (TIMES), X-ray spectroscopy, X-ray Technology   

    From SLAC: “New SLAC Theory Institute Aims to Speed Research on Exotic Materials at Light Sources” 


    SLAC Lab

    April 11, 2017
    Glennda Chui

    A new institute at the Department of Energy’s SLAC National Accelerator Laboratory is using the power of theory to search for new types of materials that could revolutionize society – by making it possible, for instance, to transmit electricity over power lines with no loss.

    The Theory Institute for Materials and Energy Spectroscopies (TIMES) focuses on improving experimental techniques and speeding the pace of discovery at West Coast X-ray facilities operated by SLAC and by Lawrence Berkeley National Laboratory, its DOE sister lab across the bay.

    But the institute aims to have a much broader impact on studies aimed at developing new materials for energy and other technological applications by making the tools it develops available to scientists around the world.

    TIMES opened in August 2016 as part of the Stanford Institute for Materials and Energy Sciences (SIMES), a DOE-funded institute operated jointly with Stanford.

    Materials that Surprise

    “We’re interested in materials with remarkable properties that seem to emerge out of nowhere when you arrange them in particular ways or squeeze them down into a single, two-dimensional layer,” says Thomas Devereaux, a SLAC professor of photon science who directs both TIMES and SIMES.

    This general class of materials is known as “quantum materials.” Some of the best-known examples are high-temperature superconductors, which conduct electricity with no loss; topological insulators, which conduct electricity only along their surfaces; and graphene, a form of pure carbon whose superior strength, electrical conductivity and other surprising qualities derive from the fact that it’s just one layer of atoms thick.

    In another research focus, Devereaux says, “We want to see what happens when you push materials far beyond their resting state – out of equilibrium, is the way we put it – by exciting them in various ways with pulses of X-ray light at facilities known as light sources.

    “This tells you how materials will behave under realistic operating conditions, for instance in a lightweight airplane or a new type of battery. Understanding and controlling out-of-equilibrium behavior and learning how novel properties emerge in complex materials are two of the scientific grand challenges in our field, and light sources are ideal places to do this work.”

    Joining Forces With Light Sources

    A key part of the institute’s work is to use theory and computation to improve experimental techniques – especially X-ray spectroscopy, which probes the chemical composition and electronic structure of materials – in order to make research at light sources more productive.

    “We are in a golden age of X-ray spectroscopy, in which many billions of dollars have been invested worldwide to develop new X-ray and neutron sources that allow us to study very small details and very fast processes in materials,” Devereaux says. “In fact, we are on the threshold of being able to control matter at a much deeper level than ever possible before.

    “But while X-ray spectroscopy has a long history of collaboration between experimentalists and theorists, there has not been a companion theory institute anywhere. TIMES fills this gap. It aims to solidify collaboration and development of new methods and tools for theory relevant to this new landscape.”

    Devereaux, a theorist who uses computation to study quantum materials, came to SLAC 10 years ago from the University of Waterloo in Canada to work more closely with researchers at three light sources – SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), Berkeley Lab’s Advanced Light Source (ALS) and the Linac Coherent Light Source (LCLS), the world’s first X-ray free-electron laser, which at the time was under construction at SLAC. Opened for research in 2009, LCLS gives scientists access to pulses a billion times brighter than any available before and that arrive up to 120 times per second, opening whole new avenues for research.

    SLAC/SSRL

    LBNL/ALS

    SLAC LCLS

    SLAC/LCLS II

    With LCLS, Devereaux says, “It became clear that we had an unprecedented opportunity to study materials that have been pushed farther away from equilibrium than was ever possible before.”

    Basic Questions and Practical Answers

    The DOE-funded theory institute has hired two staff scientists, Chunjing Jia and Das Pemmaraju, and works closely with SLAC staff scientists Brian Moritz and Hongchen Jiang and with a number of scientists at the three light sources.

    “We have two main goals,” Jia says. “One is to use X-ray spectroscopy and other techniques to look at practical materials, like the ones in batteries – to study the charging and discharging process and see how the structure of the battery changes, for instance. The second is to understand the fundamental underlying physics principles that govern the behavior of materials.”

    Eventually, she added, theorists want to understand those physics principles so well that they can predict the results of high-priority experiments at facilities that haven’t even been built yet – for instance at LCLS-II, a major upgrade to LCLS that will add a much brighter X-ray laser beam that fires up to a million pulses per second. These predictions have the potential to make experiments at new facilities much more productive and efficient.

    Running Experiments in Supercomputers

    Theoretical work can involve a lot of math and millions of hours of supercomputer time, as theorists struggle to clarify how the fundamental laws of quantum mechanics apply to the materials they are investigating, Pemmaraju says.

    “We use these laws in a form that can be simulated on a computer to make predictions about new materials and their properties,” he says. “The full richness and complexity of the theory are still being discovered, and its equations can only be solved approximately with the aid of supercomputers.”

    Jia adds that you can think of these computer simulations as numerical experiments – working “in silico,” rather than at a lab bench. By simulating what’s going on in a material, scientists can decide which of all the experimental options are the best ones, saving both time and money.

    The institute’s core research team includes theorists Joel Moore of the University of California, Berkeley and John Rehr of the University of Washington. Rehr is the developer of FEFF, an efficient and widely accessible software code that is used by the X-ray light source community worldwide. Devereaux says the plan is to establish a center for FEFF within the institute, which will serve as a home for its further development and for making those advances widely available to theorists and experimentalists at various levels of sophistication.

    TIMES and SIMES are funded by the DOE Office of Science, and the three light sources – ALS, SSRL and LCLS – are DOE Office of Science User Facilities.

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  • richardmitnick 8:54 am on April 10, 2017 Permalink | Reply
    Tags: , , Ultrafast X-ray spectroscopy, X-ray Technology   

    From LBNL: “Coming to a Lab Bench Near You: Femtosecond X-Ray Spectroscopy” 

    Berkeley Logo

    Berkeley Lab

    April 6, 2017
    Sarah Yang
    scyang@lbl.gov
    (510) 486-4575

    1
    Upon light activation (in purple, bottom row’s ball-and-stick diagram), the cyclic structure of the 1,3-cyclohexadiene molecule rapidly unravels into a near-linear shape in just 200 femtoseconds. Using ultrafast X-ray spectroscopy, researchers have captured in real time the accompanying transformation of the molecule’s outer electron “clouds” (in yellow and teal, top row’s sphere diagram) as the structure unfurls. (Credit: Kristina Chang/Berkeley Lab)

    The ephemeral electron movements in a transient state of a reaction important in biochemical and optoelectronic processes have been captured and, for the first time, directly characterized using ultrafast X-ray spectroscopy at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).

    Like many rearrangements of molecular structures, the ring-opening reactions in this study occur on timescales of hundreds of femtoseconds (1 femtosecond equals a millionth of a billionth of a second). The researchers were able to collect snapshots of the electronic structure during the reaction by using femtosecond pulses of X-ray light on a tabletop apparatus.

    The experiments are described in the April 7 issue of the journal Science.

    “Much of the work over the past decades characterizing molecules and materials has focused on X-ray spectroscopic investigations of static or non-changing systems,” said study principal investigator Stephen Leone, faculty scientist at Berkeley Lab’s Chemical Sciences Division and UC Berkeley professor of chemistry and physics. “Only recently have people started to push the time domain and look for transient states with X-ray spectroscopy on timescales of femtoseconds.”

    The researchers focused on the structural rearrangements that occur when a molecule called 1,3 cyclohexadiene (CHD) is triggered by light, leading to a higher-energy rearrangement of electrons, known as an excited state. In this excited state, the cyclic molecule of six carbon atoms in a ring opens up into a linear six-carbon chain molecule. The ring-opening is driven by an extremely fast exchange of energy between the motions of the atomic nuclei and the new, dynamic electronic configuration.

    This light-activated, ring-opening reaction of cyclic molecules is a ubiquitous chemical process that is a key step in the photobiological synthesis of vitamin D in the skin and in optoelectronic technologies underlying optical switching, optical data storage, and photochromic devices.

    2
    Berkeley Lab postdoctoral researcher Kirsten Schnorr (left), chemistry Ph.D. student research assistant Andrew Attar (center), and postdoctoral researcher Aditi Bhattacherjee (right) make preparations for an experiment on the ultrafast x-ray apparatus. (Credit: Tian Xue/Berkeley Lab)

    In order to characterize the electronic structure during the ring-opening reaction of CHD, the researchers took advantage of the unique capabilities of X-ray light as a powerful tool for chemical analysis. In their experiments, the researchers used an ultraviolet pump pulse to trigger the reaction and subsequently probe the progress of the reaction at a controllable time delay using the X-ray flashes. At a given time delay following the UV light exposure, the researchers measure the wavelengths (or energies) of X-ray light that are absorbed by the molecule in a technique known as time-resolved X-ray spectroscopy.

    “The key to our experiment is to combine the powerful advantages of X-ray spectroscopy with femtosecond time resolution, which has only recently become possible at these photon energies,” said study lead author Andrew Attar, a UC Berkeley Ph.D. student in chemistry. “We used a novel instrument to make an X-ray spectroscopic ‘movie’ of the electrons within the CHD molecule as it opens from a ring to a linear configuration. The spectroscopic still frames of our ‘movie’ encode a fingerprint of the molecular and electronic structure at a given time.”

    In order to unambiguously decode the spectroscopic fingerprints that were observed experimentally, a series of theoretical simulations were performed by researchers at Berkeley Lab’s Molecular Foundry and the Theory Institute for Materials and Energy Spectroscopies (TIMES) at DOE’s SLAC National Accelerator Laboratory. The simulations modeled both the ring-opening process and the interaction of the X-rays with the molecule during its transformation.

    “The richness and complexity of dynamical X-ray spectroscopic signatures such as the ones captured in this study require a close synergy with theoretical simulations that can directly model and interpret the experimentally observed quantities,” said Das Pemmaraju, project scientist at Berkeley Lab’s Chemical Sciences Division and an associate staff scientist at TIMES.

    The use of femtosecond X-ray pulses on a laboratory benchtop scale is one of the key technological milestones to emerge from this study.

    “We have used a tabletop, laser-based light source with pulses of X-rays at energies that have so far been limited only to large-facility sources,” said Attar.

    The X-ray pulses are produced using a process known as high-harmonic generation, wherein the infrared frequencies of a commercial femtosecond laser are focused into a helium-filled gas cell and, through a nonlinear interaction with the helium atoms, are up-converted to X-ray frequencies. The infrared frequencies were multiplied by a factor of about 300.

    The researchers are now utilizing the instrument to study myriad light-activated chemical reactions with a particular focus on reactions that are relevant to combustion.

    “These studies promise to expand our understanding of the coupled evolution of molecular and electronic structure, which lies at the heart of chemistry,” said Attar.

    Other co-authors of the study are Aditi Bhattacherjee and Kirsten Schnorr at Berkeley Lab’s Chemical Sciences Division and UC Berkeley’s Department of Chemistry; and Kristina Closser and David Prendergast at Berkeley Lab’s Molecular Foundry.

    The work was primarily supported by DOE’s Office of Science. The Molecular Foundry is a DOE Office of Science User Facility.

    See the full article here .

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  • richardmitnick 12:11 pm on March 28, 2017 Permalink | Reply
    Tags: , , , , , X-ray Technology   

    From FNAL: “LCLS-II prototype cryomodule: a success story 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    March 22, 2017
    Rich Stanek

    1
    More than 150 people at Fermilab have contributed to the design and assembly of the prototype cryomodule for LCLS-II. Photo: Reidar Hahn


    SLAC LCLS-II

    A project is like a good book: As you complete one chapter you start the next, but sometimes you cannot wait and you read ahead.

    The LCLS-II project, a next-generation X-ray light source being built at SLAC, one that is based on a superconducting RF electron linac operating in continuous-wave mode, has completed Chapter One – the prototype cryomodule (pCM). And now we are already well into the assembly of the second, third and fourth cryomodules.

    As one of the partner labs, Fermilab is responsible for the design of LCLS-II’s 1.3-gigahertz cryomodules, as well as assembly and testing for 19 of them. (LCLS-II will have a total of 40 of these cryomodules, and Jefferson Lab is assembling the rest.) Additionally, Fermilab is designing and will assemble and test three 3.9-gigahertz cryomodules and has responsibility for the procurement of the cryogenic distribution system for the LCLS-II linear accelerator.

    The pCM assembly and testing have been very successful, due in large part to the technical skills and dedication to quality of our entire team. Still, it was a learning experience, which has made our SRF and cryogenic organizations in the Accelerator and Technical divisions stronger and more tightly connected.

    The pCM met most of its acceptance criteria, to the point where it could be used in the LCLS-II linac. The majority of the design has been verified; the energy gain exceeds the specification; the average quality factor exceeds the goal and sets a new world record (3.0 x 1010); the superconducting magnet meets specification; the new tuner design was verified; the modified fundamental power coupler (in continuous-wave operation) was shown to meet specification; instrumentation and controls worked as planned; and the implementation of magnetic hygiene (first time in a cryomodule) was very successful.

    The one issue that remains is to reduce the microphonics levels so as to allow better amplitude and phase control of the cryomodule’s eight accelerating cavities, which must operate in unison.

    I must stress again how this success was driven by our team effort. Particularly evident in the pCM testing was the ability of the Technical and Accelerator division personnel to work together to accomplish the task at hand.

    The challenge to design, build and test the prototype CM drew on the work of a wide range of team members across many organizations. From beginning to end, the team functioned well. Contributions were made by staff responsible for design, procurement, part inspection, component handling and transportation, cavity testing and qualification, machining and welding, string assembly, cryomodule assembly, leak checking, installation, RF power and controls, cryogenics, and testing.

    In all, more than 150 individuals at Fermilab are contributing to the LCLS-II effort, and each has reason to be proud of their work. I am very fortunate to be able to lead this team, and I’m thankful for their dedication and strong efforts.

    Just as with a good book, once you start reading you cannot put it down; the better the book, the more motivated you are to complete reading it. So it is with this project as we are now into the execution phase. We have gotten a taste of our first success and look forward to the next chapters of the story and to completing our work.

    Rich Stanek is the Fermilab LCLS-II senior team leader.

    See the full article here .

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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 11:52 am on March 1, 2017 Permalink | Reply
    Tags: , , , Scientists develop spectacles for X-ray lasers, X-ray laser beam, X-ray Technology   

    From DESY: “Scientists develop spectacles for X-ray lasers” 

    DESY
    DESY

    2017/03/01

    Tailor-made corrective glasses permit unparalleled concentration of X-ray beam

    An international team of scientists has tailored special X-ray glasses to concentrate the beam of an X-ray laser stronger than ever before. The individually produced corrective lens eliminates the inevitable defects of an X-ray optics stack almost completely and concentrates three quarters of the X-ray beam to a spot with 250 nanometres (millionths of a millimetre) diameter, closely approaching the theoretical limit. The concentrated X-ray beam can not only improve the quality of certain measurements, but also opens up entirely new research avenues, as the team surrounding DESY lead scientist Christian Schroer writes in the journal Nature Communications.

    1
    Profile of the focused X-ray beam, without (top) and with (bottom) the corrective lens. Credit: Frank Seiboth, DESY

    Although X-rays obey the same optical laws as visible light, they are difficult to focus or deflect: “Only a few materials are available for making suitable X-ray lenses and mirrors,” explains co-author Andreas Schropp from DESY. “Also, since the wavelength of X-rays is very much smaller than that of visible light, manufacturing X-ray lenses of this type calls for a far higher degree of precision than is required in the realm of optical wavelengths – even the slightest defect in the shape of the lens can have a detrimental effect.”

    The production of suitable lenses and mirrors has already reached a very high level of precision, but the standard lenses, made of the element beryllium, are usually slightly too strongly curved near the centre, as Schropp notes. “Beryllium lenses are compression-moulded using precision dies. Shape errors of the order of a few hundred nanometres are practically inevitable in the process.” This results in more light scattered out of the focus than unavoidable due to the laws of physics. What’s more, this light is distributed quite evenly over a rather large area.

    2
    The X-ray spectacles under an electron microscope. Credit: DESY NanoLab

    Such defects are irrelevant in many applications. “However, if you want to heat up small samples using the X-ray laser, you want the radiation to be focussed on an area as small as possible,” says Schropp. “The same is true in certain imaging techniques, where you want to obtain an image of tiny samples with as much details as possible.”

    In order to optimise the focussing, the scientists first meticulously measured the defects in their portable beryllium X-ray lens stack. They then used these data to machine a customised corrective lens out of quartz glass, using a precision laser at the University of Jena. The scientists then tested the effect of these glasses using the LCLS X-ray laser at SLAC National Accelerator Laboratory in the U.S.

    “Without the corrective glasses, our lens focused about 75 per cent of the X-ray light onto an area with a diameter of about 1600 nanometres. That is about ten times as large as theoretically achievable,” reports principal author Frank Seiboth from the Technical University of Dresden, who now works at DESY. “When the glasses were used, 75 per cent of the X-rays could be focused into an area of about 250 nanometres in diameter, bringing it close to the theoretical optimum.” With the corrective lens, about three times as much X-ray light was focused into the central speckle than without it. In contrast, the full width at half maximum (FWHM), the generic scientific measure of focus sharpness in optics, did not change much and remained at about 150 nanometres, with or without the glasses.

    3
    Scheme of the experimental set-up. Credit: Frank Seiboth, DESY

    The same combination of mobile standard optics and tailor-made glasses has also been studied by the team at DESY’s synchrotron X-ray source PETRA III and the British Diamond Light Source. In both cases, the corrective lens led to a comparable improvement to that seen at the X-ray laser. “In principle, our method allows an individual corrective lens to be made for every X-ray optics,” explains lead scientist Schroer, who is also a professor of physics at the University of Hamburg.

    “These so-called phase plates can not only benefit existing X-ray sources, but in particular they could become a key component of next-generation X-ray lasers and synchrotron light sources,” emphasises Schroer. “Focusing X-rays to the theoretical limits is not only a prerequisite for a substantial improvement in a range of different experimental techniques; it can also pave the way for completely new methods of investigation. Examples include the non-linear scattering of particles of light by particles of matter, or creating particles of matter from the interaction of two particles of light. For these methods, the X-rays need to be concentrated in a tiny space which means efficient focusing is essential.”

    Involved in this research project were the Technical University of Dresden, the Universities of Jena and Hamburg, KTH Royal Institute of Technology in Stockholm, Diamond Light Source, SLAC National Accelerator Laboratory and DESY.

    See the full article here .

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    desi

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

     
  • richardmitnick 2:45 pm on February 23, 2017 Permalink | Reply
    Tags: , , Instrument finds new earthly purpose, , , , Spectrometry, , X-ray Technology   

    From Symmetry: “Instrument finds new earthly purpose” 

    Symmetry Mag

    Symmetry

    02/23/17
    Amanda Solliday

    1
    Nordlund and his colleagues—Sangjun Lee, a SLAC postdoctoral research fellow, and Jamie Titus, a Stanford University doctoral student (pictured above at SSRL, from left: Lee, Titus and Nordlund)—have already used the transition-edge-sensor spectrometer at SSRL to probe for nitrogen impurities in nanodiamonds and graphene, as well as closely examine the metal centers of proteins and bioenzymes, such as hemoglobin and photosystem II. The project at SLAC was developed with 
support by the Department of Energy’s Laboratory Directed Research and Development.
    Andy Freeberg, SLAC National Accelerator Laboratory

    Detectors long used to look at the cosmos are now part of X-ray experiments here on Earth.

    Modern cosmology experiments—such as the BICEP instruments and the in Antarctica—rely on superconducting photon detectors to capture signals from the early universe.

    BICEP 3 at the South Pole
    BICEP 3 at the South Pole

    Keck Array
    Keck Array at the South Pole

    These detectors, called transition edge sensors, are kept at temperatures near absolute zero, at only tenths of a Kelvin. At this temperature, the “transition” between superconducting and normal states, the sensors function like an extremely sensitive thermometer. They are able to detect heat from cosmic microwave background radiation, the glow emitted after the Big Bang, which is only slightly warmer at around 3 Kelvin.

    Scientists also have been experimenting with these same detectors to catch a different form of light, says Dan Swetz, a scientist at the National Institute of Standards and Technology. These sensors also happen to work quite well as extremely sensitive X-ray detectors.

    NIST scientists, including Swetz, design and build the thin, superconducting sensors and turn them into pixelated arrays smaller than a penny. They construct an entire X-ray spectrometer system around those arrays, including a cryocooler, a refrigerator that can keep the detectors near absolute zero temperatures.

    2

    TES array and cover shown with penny coin for scale.
    Dan Schmidt, NIST

    Over the past several years, these X-ray spectrometers built at the NIST Boulder MicroFabrication Facility have been installed at three synchrotrons at US Department of Energy national laboratories: the National Synchrotron Light Source at Brookhaven National Laboratory, the Advanced Photon Source [APS] at Argonne National Laboratory and most recently at the Stanford Synchrotron Radiation Lightsource [SSRL] at SLAC National Accelerator Laboratory.

    BNL NSLS-II Interior
    BNL NSLS-II Interior

    ANL APS interior
    ANL APS interior

    SLAC/SSRL
    SLAC/SSRL

    Organizing the transition edge sensors into arrays made a more powerful detector. The prototype sensor—built in 1995—consisted of only one pixel.

    These early detectors had poor resolution, says physicist Kent Irwin of Stanford University and SLAC. He built the original single-pixel transition edge sensor as a postdoc. Like a camera, the detector can capture greater detail the more pixels it has.

    “It’s only now that we’re hitting hundreds of pixels that it’s really getting useful,” Irwin says. “As you keep increasing the pixel count, the science you can do just keeps multiplying. And you start to do things you didn’t even conceive of being possible before.”

    Each of the 240 pixels is designed to catch a single photon at a time. These detectors are efficient, says Irwin, collecting photons that may be missed with more conventional detectors.

    Spectroscopy experiments at synchrotrons examine subtle features of matter using X-rays. In these types of experiments, an X-ray beam is directed at a sample. Energy from the X-rays temporarily excites the electrons in the sample, and when the electrons return to their lower energy state, they release photons. The photons’ energy is distinctive for a given chemical element and contains detailed information about the electronic structure.

    As the transition edge sensor captures these photons, every individual pixel on the detector functions as a high-energy-resolution spectrometer, able to determine the energy of each photon collected.

    The researchers combine data from all the pixels and make note of the pattern of detected photons across the entire array and each of their energies. This energy spectrum reveals information about the molecule of interest.

    These spectrometers are 100 times more sensitive than standard spectrometers, says Dennis Nordlund, SLAC scientist and leader of the transition edge sensor project at SSRL. This allows a look at biological and chemical details at extremely low concentrations using soft (low-energy) X-rays.

    “These technology advances mean there are many things we can do now with spectroscopy that were previously out of reach,” Nordlund says. “With this type of sensitivity, this is when it gets really interesting for chemistry.”

    The early experiments at Brookhaven looked at bonding and the chemical structure of nitrogen-bearing explosives. With the spectrometer at Argonne, a research team recently took scattering measurements on high-temperature superconducting materials.

    “The instruments are very similar from a technical standpoint—same number of sensors, similar resolution and performance,” Swetz says. “But it’s interesting, the labs are all doing different science with the same basic equipment.”

    At NIST, Swetz says they’re working to pair these detectors with less intense light sources, which could enable researchers to do X-ray experiments in their personal labs.

    There are plans to build transition-edge-sensor spectrometers that will work in the higher energy hard X-ray region, which scientists at Argonne are working on for the next upgrade of Advanced Photon Source.

    To complement this, the SLAC and NIST collaboration is engineering spectrometers that will handle the high repetition rate of X-ray laser pulses such as LCLS-II, the next generation of the free-electron X-ray laser at SLAC. This will require faster readout systems. The goal is to create a transition-edge-sensor array with as many as 10,000 pixels that can capture more than 10,000 pulses per second.

    Irwin points out that the technology developed for synchrotrons, LCLS-II and future cosmic-microwave-background experiments provides shared benefit.

    “The information really keeps bouncing back and forth between X-ray science and cosmology,” Irwin says

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 5:01 pm on February 21, 2017 Permalink | Reply
    Tags: , , , When Rocket Science Meets X-ray Science, X-ray Technology   

    From LBNL: “When Rocket Science Meets X-ray Science” 

    Berkeley Logo

    Berkeley Lab

    February 21, 2017
    Glenn Roberts Jr.
    glennemail@gmail.com
    510-486-5582

    Berkeley Lab and NASA collaborate in X-ray experiments to ensure safety, reliability of spacecraft systems.

    1
    Francesco Panerai of Analytical Mechanical Associates Inc., a materials scientist leading a series of X-ray experiments at Berkeley Lab for NASA Ames Research Center, discusses a 3-D visualization (shown on screens) of a heat shield material’s microscopic structure in simulated spacecraft atmospheric entry conditions. The visualization is based on X-ray imaging at Berkeley Lab’s Advanced Light Source. (Credit: Marilyn Chung/Berkeley Lab)

    Note: This is the first installment in a four-part series that focuses on a partnership between NASA and Berkeley Lab to explore spacecraft materials and meteorites with X-rays in microscale detail.

    It takes rocket science to launch and fly spacecraft to faraway planets and moons, but a deep understanding of how materials perform under extreme conditions is also needed to enter and land on planets with atmospheres.

    X-ray science is playing a key role, too, in ensuring future spacecraft survive in extreme environments as they descend through otherworldly atmospheres and touch down safely on the surface.

    Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and NASA are using X-rays to explore, via 3-D visualizations, how the microscopic structures of spacecraft heat shield and parachute materials survive extreme temperatures and pressures, including simulated atmospheric entry conditions on Mars.

    Human exploration of Mars and other large-payload missions may require a new type of heat shield that is flexible and can remain folded up until needed.


    Streaking particles collide with carbon fibers in this direct simulation Monte Carlo (DSMC) calculation based on X-ray microtomography data from Berkeley Lab’s Advanced Light Source. NASA is developing new types of carbon fiber-based heat shield materials for next-gen spacecraft. The slow-motion animation represents 2 thousandths of a second. (Credit: Arnaud Borner, Tim Sandstrom/NASA Ames Research Center)

    Candidate materials for this type of flexible heat shield, in addition to fabrics for Mars-mission parachutes deployed at supersonic speeds, are being tested with X-rays at Berkeley Lab’s Advanced Light Source (ALS) and with other techniques.

    LBNL/ALS
    LBNL/ALS

    “We are developing a system at the ALS that can simulate all material loads and stresses over the course of the atmospheric entry process,” said Harold Barnard, a scientist at Berkeley Lab’s ALS who is spearheading the Lab’s X-ray work with NASA.

    The success of the initial X-ray studies has also excited interest from the planetary defense scientific community looking to explore the use of X-ray experiments to guide our understanding of meteorite breakup. Data from these experiments will be used in risk analysis and aid in assessing threats posed by large asteroids.

    The ultimate objective of the collaboration is to establish a suite of tools that includes X-ray imaging and small laboratory experiments, computer-based analysis and simulation tools, as well as large-scale high-heat and wind-tunnel tests. These allow for the rapid development of new materials with established performance and reliability.


    NASA has tested a new type of flexible heat shield, developed through the Adaptive Deployable Entry and Placement Technology (ADEPT) Project, with a high-speed blow torch at its Arc Jet Complex at NASA Ames, and has explored the microstructure of its woven carbon-fiber material at Berkeley Lab. (Credit: NASA Ames)

    This system can heat sample materials to thousands of degrees, subject them to a mixture of different gases found in other planets’ atmospheres, and with pistons stretch the material to its breaking point, all while imaging in real time their 3-D behavior at the microstructure level.

    NASA Ames Research Center (NASA ARC) in California’s Silicon Valley has traditionally used extreme heat tests at its Arc Jet Complex to simulate atmospheric entry conditions.

    Researchers at ARC can blast materials with a giant superhot blowtorch that accelerates hot air to velocities topping 11,000 miles per hour, with temperatures exceeding that at the surface of the sun. Scientists there also test parachutes and spacecraft at its wind-tunnel facilities, which can produce supersonic wind speeds faster than 1,900 miles per hour.

    Michael Barnhardt, a senior research scientist at NASA ARC and principal investigator of the Entry Systems Modeling Project, said the X-ray work opens a new window into the structure and strength properties of materials at the microscopic scale, and expands the tools and processes NASA uses to “test drive” spacecraft materials before launch.

    “Before this collaboration, we didn’t understand what was happening at the microscale. We didn’t have a way to test it,” Barnhardt said. “X-rays gave us a way to peak inside the material and get a view we didn’t have before. With this understanding, we will be able to design new materials with properties tailored to a certain mission.”

    He added, “What we’re trying to do is to build the basis for more predictive models. Rather than build and test and see if it works,” the X-ray work could reduce risk and provide more assurance about a new material’s performance even at the drawing-board stage.

    2
    Francesco Panerai holds a sample of parachute material at NASA Ames Research Center. The screen display shows a parachute prototype (left) and a magnified patch of the material at right. (Credit: Marilyn Chung/Berkeley Lab)

    Francesco Panerai, a materials scientist with NASA contractor AMA Inc. and the X-ray experiments test lead for NASA ARC, said that the X-ray experiments at Berkeley Lab were on samples about the size of a postage stamp. The experimental data is used to improve realistic computer simulations of heat shield and parachute systems.

    “We need to use modern measurement techniques to improve our understanding of material response,” Panerai said. The 3-D X-ray imaging technique and simulated planetary conditions that NASA is enlisting at the ALS provide the best pictures yet of the behavior of the internal 3-D microstructure of spacecraft materials.

    The experiments are being conducted at an ALS experimental station that captures a sequence of images as a sample is rotated in front of an X-ray beam. These images, which provide views inside the samples and can resolve details less than 1 micron, or 1 millionth of a meter, can be compiled to form detailed 3-D images and animations of samples.

    This study technique is known as X-ray microtomography. “We have started developing computational tools based on these 3-D images, and we want to try to apply this methodology to other research areas, too,” he said.

    Learn more about the research partnership between NASA and Berkeley Lab in these upcoming articles, to appear at :

    Feb. 22—The Heat is On: X-rays reveal how simulated atmospheric entry conditions impact spacecraft shielding.
    Feb. 23—A New Paradigm in Parachute Design: X-ray studies showing the microscopic structure of spacecraft parachute fabrics can fill in key details about how they perform under extreme conditions.
    Feb. 24—Getting to Know Meteors Better: Experiments at Berkeley Lab may help assess risks posed by falling Space rocks.

    The Advanced Light Source is a DOE Office of Science User Facility.

    See the full article here .

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  • richardmitnick 8:27 pm on January 5, 2017 Permalink | Reply
    Tags: A New Way to See Proteins in Motion, , , EF-X (electric field-stimulated x-ray crystallography), X-ray images of proteins, X-ray Technology   

    From ANL APS: “A New Way to See Proteins in Motion” 

    ANL Lab

    News APS at Argonne National Laboratory

    01.03.2017
    No writer credit

    1
    A new technique to watch proteins in action involves applying large voltage pulses to protein crystals simultaneously with x-ray pulses, as shown in the photo (at left) of the experimental set-up in the BioCARS beamline at the APS. At right is a close-up view of a crystal sandwiched between electrodes that deliver the voltage.

    University of Texas Southwestern Medical Center researchers, in conjunction with colleagues from the University of Chicago, have developed a new imaging technique that makes x-ray images of proteins as they move in response to electric field pulses. The method could lead to new insights into how proteins work, said senior author Dr. Rama Ranganathan, of UT Southwestern. The technique had its first application in experiments at the U.S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory. The results were published in Nature.

    “Proteins carry out the basic reactions in cells that are necessary for life: They bind to other molecules, catalyze chemical reactions, and transmit signals within the cell,” said Ranganathan. “These actions come from their internal mechanics; that is, from the coordinated motions of the network of amino acids that make up the protein.”

    Often, Ranganathan said, the motions that underlie protein function are subtle and happen on time scales ranging from trillionths of a second to many seconds.

    “So far, we have had no direct way of ‘seeing’ the motions of amino acids over this range and with atomic precision, which has limited our ability to understand, engineer, and control proteins,” he said.

    The new method, which the researchers call EF-X (electric field-stimulated x-ray crystallography), is aimed at stimulating motions within proteins and visualizing those motions in real time at atomic resolution, he said. This approach makes it possible to create video-like images of proteins in action – a goal of future research, he explained.

    The method involves subjecting proteins to large electric fields of about 1 million volts per centimeter and simultaneously reading out the effects with x-ray crystallography, he said.

    The researchers’ EF-X experiments utilizing the BioCARS 14-ID x-ray beamline at the APS, which is an Office of Science user facility, showed proteins can sustain these intense electric fields, and further that the imaging method can expose the pattern of shape changes associated with a protein’s function. Additional standard crystallography data (in the absence of electric field) were collected at beamline 11-1, at Stanford Synchrotron Radiation Lightsource at the SLAC National Accelerator laboratory, also an Office of Science user facility.

    SLAC/SSRL
    SLAC/SSRL

    “This is not the first report of seeing atomic motions in proteins, but previous reports were specialized for particular proteins and particular kinds of motions,” said Ranganathan. “Our work is the first to open up the investigation to potentially all possible motions, and for any protein that can be crystallized. It changes what we can learn.”

    Ultimately, this work could explain how proteins work in both normal and disease states, with implications in protein engineering and drug discovery. An immediate goal is to make the method simple enough for other researchers to use, he added.

    “I think this work has opened a new door to understanding protein function. It is already capable of being used broadly for many very important problems in biology and medicine. But like any new method, there is room for many improvements that will come from both us and others. The first step will be to create a way for other scientists to use this method for themselves,” Ranganathan said.

    The group reports that they used the technique to study the PDZ domain of the human ubiquitin ligase protein LNX2, and found new information regarding how the protein actually works.

    See: Doeke R. Hekstra1‡, K. Ian White1, Michael A. Socolich1, Robert W. Henning2, Vukica Šrajer2, and Rama Ranganathan1*, Electric-field-stimulated protein Mechanics, Nature 540, 400 (15 December 2016). DOI: 10.1038/nature20571

    Author affiliations: 1. UT Southwestern Medical Center, 2. The University of Chicago ‡ Present address: Harvard University

    Correspondence: *rama.ranganathan@utsouthwestern.edu

    See the full article here .

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    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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