Tagged: BNL Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 11:35 am on July 12, 2019 Permalink | Reply
    Tags: "Optimizing the Growth of Coatings on Nanowire Catalysts", BNL, , , ,   

    From Brookhaven National Lab: “Optimizing the Growth of Coatings on Nanowire Catalysts” 

    From Brookhaven National Lab

    July 8, 2019
    Ariana Manglaviti
    amanglaviti@bnl.gov
    (631) 344-2347

    Peter Genzer,
    genzer@bnl.gov
    (631) 344-3174

    1
    (Sitting from front) Iradwikanari Waluyo, Mingzhao Liu, Dario Stacchiola, (standing from front) Mehmet Topsakal, Mark Hybertsen, Deyu Lu, and Eli Stavitski at the Inner-Shell Spectroscopy beamline of Brookhaven Lab’s National Synchrotron Light Source II (NSLS-II). The scientists performed x-ray absorption spectroscopy experiments at NSLS-II to characterize the chemical state of titanium dioxide (titania) coatings on zinc oxide nanowires. They chemically processed the nanowires to make the coatings—which boost the efficiency of the nanowires in catalyzing the water-splitting reaction that produces oxygen and hydrogen, a sustainable fuel—more likely to adhere. These characterization results were coupled with electron microscopy imaging and theoretical analyses to generate a model of the amorphous (noncrystal) atomic structure of titania.

    Scientists chemically treated the surface of wire-looking nanostructures made of zinc oxide to apply a uniform coating of titanium dioxide; these semiconducting nanowires could be used as high-activity catalysts for solar fuel production.

    Solar energy harvested by semiconductors—materials whose electrical resistance is in between that of regular metals and insulators—can trigger surface electrochemical reactions to generate clean and sustainable fuels such as hydrogen. Highly stable and active catalysts are needed to accelerate these reactions, especially to split water molecules into oxygen and hydrogen. Scientists have identified several strong light-absorbing semiconductors as potential catalysts; however, because of photocorrosion, many of these catalysts lose their activity for the water-splitting reaction. Light-induced corrosion, or photocorrosion, occurs when the catalyst itself undergoes chemical reactions (oxidation or reduction) via charge carriers (electrons and “holes,” or missing electrons) generated by light excitation. This degradation limits catalytic activity.

    Now, scientists from the Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory—have come up with a technique for optimizing the activity of one such catalyst: 500-nanometer-long but relatively thin (40 to 50 nanometers) wire-looking nanostructures, or nanowires, made of zinc oxide (ZnO). Their technique—described in a paper published online in Nano Letters on May 3—involves chemically treating the surface of the nanowires in such a way that they can be uniformly coated with an ultrathin (two to three nanometers thick) film of titanium dioxide (titania), which acts as both a catalyst and protective layer.

    The CFN-led research is a collaboration between Brookhaven Lab’s National Synchrotron Light Source II (NSLS-II)—another DOE Office of Science User Facility— and Computational Science Initiative (CSI); the Center for Computational Materials Science at the Naval Research Laboratory; and the Department of Materials Science and Chemical Engineering at Stony Brook University.

    “Nanowires are ideal catalyst structures because they have a large surface area for absorbing light, and ZnO is an earth-abundant material that strongly absorbs ultraviolet light and has high electron mobility,” said co-corresponding author and study lead Mingzhao Liu, a scientist in the CFN Interface Science and Catalysis Group. “However, by themselves, ZnO nanowires do not have high enough catalytic activity or stability for the water-splitting reaction. Uniformly coating them with ultrathin films of titania, another low-cost material that is chemically more stable and more active in promoting interfacial charge transfer, enhances these properties to boost reaction efficiency by 20 percent compared to pure ZnO nanowires.”

    3
    (Background) A false-colored scanning electron microscope image of zinc oxide (ZnO) nanowires coated with titanium dioxide, or titania (TiO2). On average, the nanowires are 10 times longer than they are wide. The white-dashed inset contains a high-resolution transmission electron microscope image that distinguishes between the ZnO core and titania shell. The black-dashed inset features a structural model of the amorphous titania shell, with the red circles corresponding to oxygen atoms and the green and blue polyhedra corresponding to undercoordinated and coordinated titanium atoms, respectively.

    To “wet” the surface of the nanowires for the titania coating, the scientists combined two surface processing methods: thermal annealing and low-pressure plasma sputtering. For the thermal annealing, they heated the nanowires in an oxygen environment to remove defects and contaminants; for the plasma sputtering, they bombarded the nanowires with energetic oxygen gas ions (plasma), which ejected oxygen atoms from the ZnO surface.

    “These treatments modify the surface chemistry of the nanowires in such a way that the titania coating is more likely to adhere during atomic layer deposition,” explained Liu. “In atomic layer deposition, different chemical precursors react with a material surface in a sequential manner to build thin films with one layer of atoms at a time.”

    The scientists imaged the nanowire-shell structures with transmission electron microscopes at the CFN, shining a beam of electrons through the sample and detecting the transmitted electrons. However, because the ultrathin titania layer is not crystalline, they needed to use other methods to decipher its “amorphous” structure. They performed x-ray absorption spectroscopy experiments at two NSLS-II beamlines: Inner-Shell Spectroscopy (ISS) and In situ and Operando Soft X-ray Spectroscopy (IOS).

    “The x-ray energies at the two beamlines are different, so the x-rays interact with different electronic levels in the titanium atoms,” said co-author Eli Stavitski, ISS beamline physicist. “The complementary absorption spectra generated through these experiments confirmed the highly amorphous structure of titania, with crystalline domains limited to a few nanometers. The results also gave us information about the valence (charge) state of the titanium atoms—how many electrons are in the outermost shell surrounding the nucleus—and the coordination sphere, or the number of nearest neighboring oxygen atoms.”

    Theorists and computational scientists on the team then determined the most likely atomic structure associated with these experimental spectra. In materials with crystalline structure, the arrangement of an atom and its neighbors is the same throughout the crystal. But amorphous structures lack this uniformity or long-range order.

    “We had to figure out the correct combination of structural configurations responsible for the amorphous nature of the material,” explained co-corresponding author Deyu Lu, a scientist in the CFN Theory and Computation Group. “First, we screened an existing structural database and identified more than 300 relevant local structures using data analytics tools previously developed by former CFN postdoc Mehmet Topsakal and CSI computational scientist Shinjae Yoo. We calculated the x-ray absorption spectra for each of these structures and selected 11 representative ones as basis functions to fit our experimental results. From this analysis, we determined the percentage of titanium atoms with a particular local coordination.”

    The analysis showed that about half of the titanium atoms were “undercoordinated.” In other words, these titanium atoms were surrounded by only four or five oxygen atoms, unlike the structures in most common forms of titania, which have six neighboring oxygen atoms.

    To validate the theoretical result, Lu and the other theorists—Mark Hybertsen, leader of the CFN Theory and Computation Group; CFN postdoc Sencer Selcuk; and former CFN postdoc John Lyons, now a physical scientist at the Naval Research Lab—created an atomic-scale model of the amorphous titania structure. They applied the computational technique of molecular dynamics to simulate the annealing process that produced the amorphous structure. With this model, they also computed the x-ray absorption spectrum of titania; their calculations confirmed that about 50 percent of the titanium atoms were undercoordinated.

    “These two independent methods gave us a consistent message about the local structure of titania,” said Lu.

    “Fully coordinated atoms are not very active because they cannot bind to the molecules they do chemistry with in reactions,” explained Stavitski. “To make catalysts more active, we need to reduce their coordination.”

    “Amorphous titania transport behavior is very different from bulk titania,” added Liu. “Amorphous titania can efficiently transport both holes and electrons as active charge carriers, which drive the water-splitting reaction. But to understand why, we need to know the key atomic-scale motifs.”

    To the best of their knowledge, the scientists are the first to study amorphous titania at such a fine scale.

    “To understand the structural evolution of titania on the atomic level, we needed scientists who know how to grow active materials, how to characterize these materials with the tools that exist at the CFN and NSLS-II, and how to make sense of the characterization results by leveraging theory tools,” said Stavitski.

    Next, the team will extend their approach of combining experimental and theoretical spectroscopy data analysis to materials relevant to quantum information science (QIS). The emerging field of QIS takes advantage of the quantum effects in physics, or the strange behaviors and interactions that happen at ultrasmall scales. They hope that CFN and NSLS-II users will make use of the approach in other research fields, such as energy storage.

    This research used resources of Brookhaven Lab’s Scientific Data and Computing Center (part of CSI) and the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility operated by Lawrence Berkeley National Laboratory. The computational studies were in part supported by a DOE Laboratory Directed Research and Development (LDRD) project and the Office of Naval Research through the Naval Research Laboratory’s Basic Research Program.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 12:23 pm on July 5, 2019 Permalink | Reply
    Tags: "Creating 'Movies' of Thin Film Growth at NSLS-II", BNL, Coherent x-rays at NSLS-II enable researchers to produce more accurate observations of thin film growth in real time., , The team used a technique called x-ray photon correlation spectroscopy., Thin films are used to build some of today’s most important technologies such as computer chips and solar cells.   

    From Brookhaven National Lab “Creating ‘Movies’ of Thin Film Growth at NSLS-II” 

    From Brookhaven National Lab

    July 2, 2019
    Stephanie Kossman
    skossman@bnl.gov

    Coherent x-rays at NSLS-II enable researchers to produce more accurate observations of thin film growth in real time.

    1
    Co-authors Peco Myint (BU) and Jeffrey Ulbrandt (UVM) are shown at NSLS-II’s CHX beamline, where the research was conducted.

    From paint on a wall to tinted car windows, thin films make up a wide variety of materials found in ordinary life. But thin films are also used to build some of today’s most important technologies, such as computer chips and solar cells. Seeking to improve the performance of these technologies, scientists are studying the mechanisms that drive molecules to uniformly stack together in layers—a process called crystalline thin film growth. Now, a new research technique could help scientists understand this growth process better than ever before.

    Researchers from the University of Vermont, Boston University, and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have demonstrated a new experimental capability for watching thin film growth in real-time. Using the National Synchrotron Light Source II (NSLS-II)—a DOE Office of Science User Facility at Brookhaven—the researchers were able to produce a “movie” of thin film growth that depicts the process more accurately than traditional techniques can. Their research was published on June 14, 2019 in Nature Communications.

    2
    This animation is a simplified representation of thin film growth. As C60 molecules are deposited onto a material, they form multiple layers simultaneously—not one layer at a time. After a molecule reaches the surface of the material, it migrates by surface diffusion towards the boundary of an existing layer, or the “step-edge,” causing the step-edge to move out from the center of the mound. This process repeats as new layers are continuously formed in an organized pattern. The mound increases in height by one layer after an equivalent of one full layer of molecules has been deposited onto the material. The pattern of step-edges is self-similar after each full-layer-equivalent is deposited, just displaced one layer higher. The main result of the study is that this repeating self-similarity, or “autocorrelation,” can be quantitatively measured with coherent x-rays, and that the autocorrelations can be used to deduce certain details of how step-edges propagate during the deposition.

    How thin films grow

    Like building a brick wall, thin films “grow” by stacking in overlapping layers. In this study, the scientists focused on the growth process of a nanomaterial called C60, which is popular for its use in organic solar cells.

    “C60 is a spherical molecule that has the structure of a soccer ball,” said University of Vermont physicist Randall Headrick, lead author of the research. “There is a carbon atom at all of the corners where the ‘black’ and ‘white’ patches meet, for a total of 60 carbon atoms.”

    Though spherical C60 molecules don’t perfectly fit side-by-side like bricks in wall, they still create a uniform pattern.

    “Imagine you have a big bin and you fill it with one layer of marbles,” Headrick said. “The marbles would pack together in a nice hexagonal pattern along the bottom of the bin. Then, when you laid down the next layer of marbles, they would fit into the hollow areas between the marbles in the bottom layer, forming another perfect layer. We’re studying the mechanism that causes the marbles, or molecules, to find these ordered sites.”

    But in real life, thin films don’t stack this evenly. When filling a bin with marbles, for example, you may have three layers of marbles on one side of the bin and only one layer on the other side. Traditionally, this nonuniformity in thin films has been difficult to measure.

    “In other experiments, we could only study a single crystal that was specially polished so the whole surface behaved the same way at the same time,” Headrick said. “But that is not how materials behave in real life.”

    Studying thin film growth through coherent x-rays

    4
    A snapshot of the speckle pattern “movie” produced at CHX. The speckles are most visible at the boundaries of each color.

    To collect data that more accurately described thin film growth, Headrick went to the Coherent Hard X-ray Scattering (CHX) beamline at NSLS-II to design a new kind of experiment, one that made use of the beamline’s coherent x-rays. The team used a technique called x-ray photon correlation spectroscopy.

    “Typically, when you do an x-ray experiment, you see average information, like the average size of molecules or the average distance between them. And as the surface of a material become less uniform or ‘rougher,’ the features you look for disappear,” said Andrei Fluerasu, lead beamline scientist at CHX and a co-author of the research. “What is special about CHX is that we can use a coherent x-ray beam that produces an interference pattern, which can be thought of like a fingerprint. As a material grows and changes, its fingerprint does as well.”

    The “fingerprint” produced by CHX appears as a speckle pattern and it represents the exact arrangement of molecules in the top layer of the material. As layers continue to stack, scientists can watch the fingerprint change as if it were a movie of the thin film growth.

    “That is impossible to measure with other techniques,” Fluerasu said.

    Through computer processing, the scientists are able to convert the speckle patterns into correlation functions that are easier to interpret.

    “There are instruments like high resolution microscopes that can actually make a real image of these kinds of materials, but these images usually only show narrow views of the material,” Headrick said. “A speckle pattern that changes over time is not as intuitive, but it provides us with data that is much more relevant to the real-life case.”

    Co-author Lutz Wiegart, a beamline scientist at CHX, added, “This technique allows us to understand the dynamics of growth processes and, therefore, figure out how they relate to the quality of the films and how we can tune the processes.”

    The detailed observations of C60 from this study could be used to improve the performance of organic solar cells. Moving forward, the researchers plan to use this technique to study other types of thin films as well.

    5
    Members of the collaborating institutions are shown at NSLS-II’s CHX beamline. Pictured from left to right are Karl F. Ludwig Jr. (BU), Lutz Wiegart (NSLS-II), Randall Headrick (UVM), Xiaozhi Zhang (UVM), Jeffrey Ulbrandt (UVM), Yugang Zhang (NSLS-II), Andrei Fluerasu (NSLS-II), and Peco Myint (BU).

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 1:41 pm on June 22, 2019 Permalink | Reply
    Tags: , BNL, LBCO (lanthanum barium copper oxide) was the first high-temperature (high-Tc) superconductor discovered some 33 years ago., ,   

    From Brookhaven National Lab: “Electron (or ‘Hole’) Pairs May Survive Effort to Kill Superconductivity” 

    From Brookhaven National Lab

    June 14, 2019
    Karen McNulty Walsh,
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Emergence of unusual metallic state supports role of charge stripes in formation of charge-carrier pairs essential to resistance-free flow of electrical current.

    1
    Showing their stripes: Brookhaven Lab physicists present new evidence that stripes—alternating areas of charge and magnetism in certain copper-oxide materials—are good for forming the charge-carrier pairs needed for electrical current to flow with no resistance. Left to right: Qiang Li, Genda Gu, John Tranquada, Alexei Tsvelik, and Yangmu Li in front of an image of wind-blown ripples in desert sand.

    Scientists seeking to understand the mechanism underlying superconductivity in “stripe-ordered” cuprates—copper-oxide materials with alternating areas of electric charge and magnetism—discovered an unusual metallic state when attempting to turn superconductivity off. They found that under the conditions of their experiment, even after the material loses its ability to carry electrical current with no energy loss, it retains some conductivity—and possibly the electron (or hole) pairs required for its superconducting superpower.

    “This work provides circumstantial evidence that the stripe-ordered arrangement of charges and magnetism is good for forming the charge-carrier pairs required for superconductivity to emerge,” said John Tranquada, a physicist at the U.S. Department of Energy’s Brookhaven National Laboratory.

    Tranquada and his co-authors from Brookhaven Lab and the National High Magnetic Field Laboratory at Florida State University, where some of the work was done, describe their findings in a paper just published in Science Advances. A related paper in the Proceedings of the National Academy of Sciences by co-author Alexei Tsvelik, a theorist at Brookhaven Lab, provides insight into the theoretical underpinnings for the observations.

    2
    This image represents the stripes of magnetism and charge in the cuprate (copper and oxygen) layers of the superconductor LBCO. Gray shading represents the modulation of the charge (“holes,” or electron vacancies), which is maximized in stripes that separate areas of magnetism, indicated by arrows representing alternating magnetic orientations on adjacent copper atoms.

    The scientists were studying a particular formulation of lanthanum barium copper oxide (LBCO) that exhibits an unusual form of superconductivity at a temperature of 40 Kelvin (-233 degrees Celsius). That’s relatively warm in the realm of superconductors. Conventional superconductors must be cooled with liquid helium to temperatures near -273°C (0 Kelvin or absolute zero) to carry current without energy loss. Understanding the mechanism behind such “high-temperature” superconductivity might guide the discovery or strategic design of superconductors that operate at higher temperatures.

    “In principle, such superconductors could improve the electrical power infrastructure with zero-energy-loss power transmission lines,” Tranquada said, “or be used in powerful electromagnets for applications like magnetic resonance imaging (MRI) without the need for costly cooling.”

    The mystery of high-Tc

    LBCO was the first high-temperature (high-Tc) superconductor discovered, some 33 years ago. It consists of layers of copper-oxide separated by layers composed of lanthanum and barium. Barium contributes fewer electrons than lanthanum to the copper-oxide layers, so at a particular ratio, the imbalance leaves vacancies of electrons, known as holes, in the cuprate planes. Those holes can act as charge carriers and pair up, just like electrons, and at temperatures below 30K, current can move through the material with no resistance in three dimensions—both within and between the layers.

    3
    Copper-oxide layers of LBCO (the lanthanum-barium layers would be between these). 3-D superconductivity occurs when current can flow freely in any direction within and between the copper-oxide layers, while 2-D superconductivity exists when current moves freely only within the layers (not perpendicular). The perpendicular orientations of stripe patterns from one layer to the next may be part of what inhibits movement of current between layers.

    An odd characteristic of this material is that, in the copper-oxide layers, at the particular barium concentration, the holes segregate into “stripes” that alternate with areas of magnetic alignment. Since this discovery, in 1995, there has been much debate about the role these stripes play in inducing or inhibiting superconductivity.

    In 2007, Tranquada and his team discovered the most unusual form of superconductivity in this material at the higher temperature of 40K. If they altered the amount of barium to be just under the amount that allowed 3-D superconductivity, they observed 2-D superconductivity—meaning just within the copper-oxide layers but not between them.

    “The superconducting layers seem to decouple from one another,” Tsvelik, the theorist, said. The current can still flow without loss in any direction within the layers, but there is resistivity in the direction perpendicular to the layers. This observation was interpreted as a sign that charge-carrier pairs were forming “pair density waves” with orientations perpendicular to one another in neighboring layers. “That’s why the pairs can’t jump from layer to another. It would be like trying to merge into traffic moving in a perpendicular direction. They can’t merge,” Tsvelik said.

    Superconducting stripes are hard to kill

    In the new experiment, the scientists dove deeper into exploring the origins of the unusual superconductivity in the special formulation of LBCO by trying to destroy it. “Often times we test things by pushing them to failure,” Tranquada said. Their method of destruction was exposing the material to powerful magnetic fields generated at Florida State.

    “As the external field gets bigger, the current in the superconductor grows larger and larger to try to cancel out the magnetic field,” Tranquada explained. “But there’s a limit to the current that can flow without resistance. Finding that limit should tell us something about how strong the superconductor is.”

    4
    A phase diagram of LBCO at different temperatures and magnetic field strengths. Colors represent how resistant the material is to the flow of electrical current, with purple being a superconductor with no resistance. When cooled to near absolute zero with no magnetic field, the material acts as a 3-D superconductor. As the magnetic field strength goes up, 3-D superconductivity disappears, but 2-D superconductivity reappears at higher field strength, then disappears again. At the highest fields, resistance grew, but the material retained some unusual metallic conductivity, which the scientists interpreted as an indication that charge-carrier pairs might persist even after superconductivity is destroyed.

    For example, if the stripes of charge order and magnetism in LBCO are bad for superconductivity, a modest magnetic field should destroy it. “We thought maybe the charge would get frozen in the stripes so that the material would become an insulator,” Tranquada said.

    But the superconductivity turned out to be a lot more robust.

    Using perfect crystals of LBCO grown by Brookhaven physicist Genda Gu, Yangmu Li, a postdoctoral fellow who works in Tranquada’s lab, took measurements of the material’s resistance and conductivity under various conditions at the National High Magnetic Field Laboratory. At a temperature just above absolute zero with no magnetic field present, the material exhibited full, 3-D superconductivity. Keeping the temperature constant, the scientists had to ramp up the external magnetic field significantly to make the 3-D superconductivity disappear. Even more surprising, when they increased the field strength further, the resistance within the copper-oxide planes went down to zero again!

    “We saw the same 2-D superconductivity we’d discovered at 40K,” Tranquada said.

    Ramping up the field further destroyed the 2-D superconductivity, but it never completely destroyed the material’s ability to carry ordinary current.

    “The resistance grew but then leveled off,” Tranquada noted.

    Signs of persistent pairs?

    Additional measurements made under the highest-magnetic-field indicated that the charge-carriers in the material, though no longer superconducting, may still exist as pairs, Tranquada said.

    “The material becomes a metal that no longer deflects the flow of current,” Tsvelik said. “Whenever you have a current in a magnetic field, you would expect some deflection of the charges—electrons or holes—in the direction perpendicular to the current [what scientists call the Hall effect]. But that’s not what happens. There is no deflection.”

    In other words, even after the superconductivity is destroyed, the material keeps one of the key signatures of the “pair density wave” that is characteristic of the superconducting state.

    “My theory relates the presence of the charge-rich stripes with the existence of magnetic moments between them to the formation of the pair density wave state,” Tsvelik said. “The observation of no charge deflection at high field shows that the magnetic field can destroy the coherence needed for superconductivity without necessarily destroying the pair density wave.”

    “Together these observations provide additional evidence that the stripes are good for pairing,” Tranquada said. “We see the 2-D superconductivity reappear at high field and then, at an even higher field, when we lose the 2-D superconductivity, the material doesn’t just become an insulator. There’s still some current flowing. We may have lost coherent motion of pairs between the stripes, but we may still have pairs within the stripes that can move incoherently and give us an unusual metallic behavior.”

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 1:12 pm on June 22, 2019 Permalink | Reply
    Tags: "Researchers to Take Advantage of DOE's Advanced Supercomputers", BNL, D.O.E. Comscope   

    From Brookhaven National Lab: “Researchers to Take Advantage of DOE’s Advanced Supercomputers” 

    From Brookhaven National Lab

    June 18, 2019

    1
    Comscope is one of seven projects funded by the U.S. Department of Energy to accelerate the design of new materials through advanced computation.

    The U.S. Department of Energy announced today that it will invest $32 million over the next four years to accelerate the design of new materials through use of supercomputers.

    Seven projects will be supported, three led by teams at DOE National Laboratories and four by Universities. The teams are led by Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL) and Lawrence Livermore National Laboratory (LLNL) as well as the University of Illinois, the Pennsylvania State University, the University of Texas and the University of Southern California.

    These projects will develop widely applicable open source software utilizing DOE’s current leadership class and future exascale computing facilities. The goal is to provide the software platforms and data for the design of new functional materials with a broad range of applications, including alternative and renewable energy, electronics, data storage and materials for quantum information science.

    The new awards are part of DOE’s Computational Materials Sciences (CMS) program, begun in 2015 to reflect the enormous recent growth in computing power and the increasing capability of high-performance computers to model and simulate the behavior of matter at the atomic and molecular scales.

    “High performance computing has become an increasingly powerful tool of scientific discovery and technological innovation, and our capabilities continue to grow,” said Under Secretary for Science Paul Dabbar. “These projects will harness America’s leadership in supercomputing to deliver a new generation of materials for energy and a wide range of other applications.”

    Researchers are expected to make use of current generation petaflop supercomputers and prepare for next-generation exaflop machines scheduled for deployment in the early 2020s. Current machines include the 200-petaflop Summit computer at the Oak Ridge Leadership Computing Facility (OLCF), the 11-petaflop Theta computer at the Argonne Leadership Computing Facility (ALCF), and the 30-petaflop Cori machine at the National Energy Research Scientific Computing center (NERSC) at Lawrence Berkeley National Laboratory (LBNL). OLCF, ALCF, and NERSC are all DOE Office of Science user facilities. A petaflop is a million-billion floating-point operations per second. An exaflop is a billion-billion calculations.


    ORNL IBM AC922 SUMMIT supercomputer, No.1 on the TOP500. Credit: Carlos Jones, Oak Ridge National Laboratory/U.S. Dept. of Energy

    ANL/ALCF

    ANL ALCF Theta Cray XC40 supercomputer

    NERSC Cray Cori II supercomputer at NERSC at LBNL, named after Gerty Cori, the first American woman to win a Nobel Prize in science

    Research will combine theory and software development with experimental validation, drawing on the resources of multiple DOE Office of Science user facilities, including the Advanced Light Source at LBNL, the Advanced Photon Source at ANL, the Spallation Neutron Source at Oak Ridge National Laboratory, the Linac Coherent Light Source at SLAC National Accelerator Facility and several of the five Nanoscale Science Research Centers across the DOE national laboratory complex.

    LBNL ALS

    ANL Advanced Photon Source

    ORNL Spallation Neutron Source

    SLAC/LCLS

    Funding for the new projects will total $8 million in Fiscal Year 2019. Subsequent annual funding will be contingent on available appropriations and project performance.

    Projects were chosen by competitive peer review under a DOE Funding Opportunity Announcement for Computational Materials Sciences. The CMS program is managed by the Department’s Office of Science through its Office of Basic Energy Sciences. Projects announced today are selections for negotiation of financial award. The final details for each project award are subject to final grant and contract negotiations between DOE and the awardees. A list of awards can be found here.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 11:13 am on June 14, 2019 Permalink | Reply
    Tags: "Preparing Scientific Applications for Exascale Computing", , , BNL, Brookhaven Lab's Computational Science Initiative hosted a four-day coding workshop focusing on the latest version of OpenMP,   

    From Brookhaven National Lab: “Preparing Scientific Applications for Exascale Computing” 

    From Brookhaven National Lab

    June 11, 2019
    Ariana Tantillo
    atantillo@bnl.gov

    Brookhaven Lab’s Computational Science Initiative hosted a four-day coding workshop focusing on the latest version of OpenMP, a widely used programming standard that is being upgraded with new features to support next-generation supercomputing.

    1
    The 2019 OpenMP hackathon at Brookhaven Lab—hosted by the Computational Science Initiative from April 29 to May 2—brought together participants from Brookhaven, Argonne, Lawrence Berkeley, Lawrence Livermore, and Oak Ridge national labs; IBM; NASA; Georgia Tech; Indiana University; Rice University; and University of Illinois at Urbana-Champaign.

    Exascale computers are soon expected to debut, including Frontier at the U.S. Department of Energy’s (DOE) Oak Ridge Leadership Computing Facility (OLCF) and Aurora at the Argonne Leadership Computing Facility (ALCF), both DOE Office of Science User Facilities, in 2021.

    ORNL Cray Frontier Shasta based Exascale supercomputer with Slingshot interconnect featuring high-performance AMD EPYC CPU and AMD Radeon Instinct GPU technology

    Depiction of ANL ALCF Cray Intel SC18 Shasta Aurora exascale supercomputer

    These next-generation computing systems are projected to surpass the speed of today’s most powerful supercomputers by five to 10 times. This performance boost will enable scientists to tackle problems that are otherwise unsolvable in terms of their complexity and computation time.

    But reaching such a high level of performance will require software adaptations. For example, OpenMP—the standard application programming interfaces for shared-memory parallel computing, or the use of multiple processors to complete a task—will have to evolve to support the layering of different memories, hardware accelerators such as graphics processing units (GPUs), various exascale computing architectures, and the latest standards for C++ and other programming languages.

    3
    Exascale computers will be used to solve problems in a wide range of scientific applications, including to simulate the lifetime operations of small modular nuclear reactors (left) and to understand the complex relationship between 3-D printing processes and material properties (right). Credit: Oak Ridge National Lab.

    Evolving OpenMP toward exascale with the SOLLVE project

    In September 2016, the DOE Exascale Computing Project (ECP) funded a software development project called SOLLVE (for Scaling OpenMP via Low-Level Virtual Machine for Exascale Performance and Portability) to help with this transition.

    The SOLLVE project team—led by DOE’s Brookhaven National Laboratory and consisting of collaborators from DOE’s Argonne, Lawrence Livermore, and Oak Ridge National Labs, and Georgia Tech—has been designing, implementing, and standardizing key OpenMP functionalities that ECP application developers have identified as important.

    Driven by SOLLVE and sponsored by ECP, Brookhaven Lab’s Computational Science Initiative (CSI) hosted a four-day OpenMP hackathon from April 29 to May 2, jointly organized with Oak Ridge and IBM. The OpenMP hackathon is the latest in a series of hackathons offered by CSI, including those focusing on NVIDIA GPUs and Intel Xeon Phi many-core processors.

    “OpenMP is undergoing substantial changes to address the requirements of upcoming exascale computing systems,” said local event coordinator Martin Kong, a computational scientist in CSI’s Computer Science and Mathematics Group and the Brookhaven Lab representative on the OpenMP Architecture Review Board, which oversees the OpenMP standard specification. “Porting scientific codes to the new exascale hardware and architectures will be a grand challenge. The main motivation of this hackathon is application engagement—to interact more deeply with different users, especially those from DOE labs, and make them aware of the changes they should expect in OpenMP and how these changes can benefit their scientific applications.”

    Laying the foundation for application performance portability

    ORNL IBM AC922 SUMMIT supercomputer, No.1 on the TOP500. Credit: Carlos Jones, Oak Ridge National Laboratory/U.S. Dept. of Energy

    Computational and domain scientists, code developers, and computing hardware experts from Brookhaven, Argonne, Lawrence Berkeley, Lawrence Livermore, Oak Ridge, Georgia Tech, Indiana University, Rice University, University of Illinois at Urbana-Champaign, IBM, and the National Aeronautics and Space Administration (NASA) participated in the hackathon. The eight teams were guided by national lab, university, and industry mentors who were selected based on their extensive experience in programming GPUs, participating in the OpenMP Language Committee, and conducting research and development in tools that support the latest OpenMP specifications.

    Throughout the week, the teams worked on porting their scientific applications from central processing units (CPU) to GPUs and optimizing them using the latest OpenMP version (4.5+). In between hacking sessions, the teams had tutorials on various advanced OpenMP features, including accelerator programming, profiling tools to assess performance, and application optimization strategies.

    Some teams also used the latest OpenMP functionalities to program IBM Power9 CPUs accelerated with NDIVIA GPUs. The world’s fastest supercomputer—the Summit supercomputer at OLCF—is based on this new architecture, with more than 9000 IBM Power9 CPUs and more than 27,000 NVIDIA GPUs.

    Taking steps toward exascale

    The teams’ applications spanned many areas, including nuclear and high-energy physics, lasers and optics, materials science, autonomous systems, and fluid mechanics.

    Participant David Wagner of the NASA Langley Research Center High Performance Computing Incubator and colleagues Gabriele Jost and Daniel Kokron of the NASA Ames Research Center came with a code for simulating elasticity. Their goal at the hackathon was to increase single-instruction, multiple-data (SIMD) parallelism—a type of computing in which multiple processors perform the same operation on many data points simultaneously—and optimize the speed at which data can be read from and stored into memory.

    “Scientists at NASA are trying to understand how and why aircraft and spacecraft materials fail,” said Wagner. “We need to make sure that these materials are durable enough to withstand all of the forces that are present in normal use during service. At the hackathon, we’re working on a mini app that is representative of the most computationally intensive parts of the larger program to model what happens physically when the materials are loaded, bent, and stretched. Our code has lots of little formulas that need to run billions of times over. The challenge is performing all of the calculations really fast.”

    According to Wagner, one of the reasons NASA is pushing for this computational capability now is to understand the processes used to generate additively manufactured (3-D printed) parts and the different material properties of these parts, which are increasingly being used in aircraft. Knowing this information is important to ensuring the safety, reliability, and durability of the materials over their operational lifetimes.

    “The hackathon was a success for us,” said Wagner. “We got our code set up for massively parallel execution and running correctly on GPU hardware. We’ll continue with debugging and parallel performance tuning, as we expect to have suitable NASA hardware and software available soon.”

    Another team took a similar approach in trying to get OpenMP to work for a small portion of their code, a lattice quantum chromodynamics (QCD) code that is at the center of an ECP project called Lattice QCD: Lattice Quantum Chromodynamics for Exascale. Lattice QCD is a numerical framework for simulating the strong interactions between elementary particles called quarks and gluons. Such simulations are important to many high-energy and nuclear physics problems. Typical simulations require months of running on supercomputers.

    4
    A schematic of the lattice for quantum chromodynamics calculations. The intersection points on the grid represent quark values, while the lines between them represent gluon values.

    “We would like our code to run on different exascale architectures,” said team member and computational scientist Meifeng Lin, deputy group lead of CSI’s new Quantum Computing Group and local coordinator of previous hackathons. “Right now, the code runs on NVIDIA GPUs but upcoming exascale computers are expected to have at least two different architectures. We hope that by using OpenMP, which is supported by major hardware vendors, we will be able to more easily port our code to these emerging platforms. We spent the first two days of the hackathon trying to get OpenMP to offload code from CPU to GPU across the entire library, without much success.”

    Mentor Lingda Li, a CSI research associate and a member of the SOLLVE project, helped Lin and fellow team member Chulwoo Jung, a physicist in Brookhaven’s High-Energy Theory Group, with the OpenMP offloading.

    Though the team was able to get OpenMP to work with a few hundred lines of code, its initial performance was poor. They used various performance profiling tools to determine what was causing the slowdown. With this information, they were able to make foundational progress in their overall optimization strategy, including solving problems related to initial GPU offloading and simplifying data mapping.

    Among the profiling tools available to teams at the hackathon was one developed by Rice University and University of Wisconsin.

    5
    John Mellor-Crummey gives a presentation about the HPCToolkit, an integrated suite of tools for measuring and analyzing program performance on systems ranging from desktops to supercomputers.

    “Our tool measures the performance of GPU-accelerated codes both on the host and the GPU,” said John Mellor-Crummey, professor of computer science and electrical and computer engineering at Rice University and the principal investigator on the corresponding ECP project Extending HPCToolkit to Measure and Analyze Code Performance on Exascale Platforms. “We’ve been using it on several simulation codes this week to look at the relative performance of computation and data movement in and out of GPUs. We can tell not only how long a code is running but also how many instructions were executed and whether the execution was at full speed or stalled, and if stalled, why. We also identified mapping problems with the compiler information that associates machine code and source code.”

    Other mentors from IBM were on hand to show the teams how to use IBM XL compilers—which are designed to exploit the full power of IBM Power processors—and help them through any issues they encountered.

    “Compilers are tools that scientists use to translate their scientific software into code that can be read by hardware, by the largest supercomputers in the world—Summit and Sierra [at Lawrence Livermore],” said Doru Bercea, a research staff member in the Advanced Compiler Technologies Group at the IBM TJ Watson Research Center. “The hackathon provides us with an opportunity to discuss compiler design decisions to get OpenMP to work better for scientists.”

    According to mentor Johannes Doerfert, a postdoctoral scholar at ALCF, the applications the teams brought to the hackathon were at various stages in terms of their readiness for upcoming computing systems.

    6
    QMCPack can be used to calculate the ground and excited state energies of localized defects in insulators and semiconductors—for example, in manganese (Mn)4+-doped phosphors, which are promising materials for improving the color quality and luminosity of white-light-emitting diodes. Source: Journal of Physical Chemistry Review Letters.

    “Some teams are facing porting problems, some are struggling with the compilers, and some have application performance issues,” explained Doerfert. “As mentors, we receive questions coming from anywhere in this large spectrum.”

    Some of the other scientific applications that teams brought include a code (pf3d) for simulating the interactions between high-intensity lasers and plasma (ionized gas) in experiments at Lawrence Livermore’s National Ignition Facility, and a code for calculating the electronic structure of atoms, molecules, and solids (QMCPack, also an ECP project). Another ECP team brought a portable programming environment (RAJA) for the C++ programming language.

    “We’re developing a high-level abstraction called RAJA so people can use whatever hardware or software frameworks are available on the backend of their computer systems,” said mentor Tom Scogland, a postdoctoral scholar in the Center for Applied Scientific Computing at Lawrence Livermore. “RAJA mainly targets OpenMP on the host and CUDA [another parallel computing programming model] on the backend. But we want RAJA to work with other programming models on the backend, including OpenMP.”

    “The theme of the hackathon was OpenMP 4.5+, an evolving and not fully mature version,” explained Kong. “The teams left with a better understanding of the new OpenMP features, knowledge about the new tools that are becoming available on Summit, and a roadmap to follow in the long term.”

    “I learned a number of things about OpenMP 4.5,” said pf3d team member Steve Langer, a computational physicist at Lawrence Livermore. “The biggest benefit was the discussions with mentors and IBM employees. I now know how to package my OpenMP offload directives to use NVIDIA GPUs without running into memory limitations.”

    A second OpenMP hackathon will be held in July at Oak Ridge and a third in August at the National Energy Research Scientific Computing Center, a division of Lawrence Berkeley, a DOE Office of Science User Facility, and the primary computing facility for DOE Office of Science–supported researchers.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 8:16 am on June 7, 2019 Permalink | Reply
    Tags: Accelerator physicists have demonstrated a groundbreaking technique using bunches of electrons to keep beams of particles cool at the Relativistic Heavy Ion Collider, BNL, Electron Bunches Keep Ions Cool at RHIC, , The team had to build and commission a new state-of-the-art electron accelerator that would fit inside the RHIC tunnel., This included using more compact radiofrequency (RF) acceleration technology rather than the standard direct-current (DC) method used in all previous electron-cooling setups., World's first demonstration of "bunched-beam" electron cooling at low energy in RHIC opens the possibility of using this technique at high energies for a variety of applications.   

    From Brookhaven National Lab: “Electron Bunches Keep Ions Cool at RHIC” 

    From Brookhaven National Lab

    6.7.19
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    World’s first demonstration of “bunched-beam” electron cooling at low energy in RHIC opens the possibility of using this technique at high energies for a variety of applications.

    1
    Some members of the Low Energy RHIC electron Cooling (LEReC) team in the Main Control Room of Brookhaven Lab’s Collider-Accelerator Department. The team successfully demonstrated a bunched-beam electron cooling technique at RHIC, opening up the possibility of applying this technique to produce high-quality ion beams at high energies.

    Accelerator physicists have demonstrated a groundbreaking technique using bunches of electrons to keep beams of particles cool at the Relativistic Heavy Ion Collider (RHIC)—a U.S. Department of Energy Office of Science user facility for nuclear physics research at Brookhaven National Laboratory. This “bunched-beam” electron cooling technique will enable higher particle collision rates at RHIC, where scientists study the collision debris to learn about the building blocks of matter as they existed just after the Big Bang.

    2
    Brookhaven Lab engineer Mathew Paniccia next to the LEReC cooling sections. Electrons have successfully cooled bunches of ions in these cooling sections of the Relativistic Heavy Ion Collider (RHIC).

    Brookhaven’s accelerator team is testing the method at the collider’s lowest energies—a regime where data has been scarce yet is crucial to understanding how the particles that filled the early universe transformed into the ordinary matter that makes up our world today.

    “The low-energy conditions are actually the most challenging for this technique,” said Alexei Fedotov, the Brookhaven Lab accelerator physicist who led the effort and the team of nearly 100 people who made it happen.

    “Now that we’ve demonstrated bunched-beam cooling in the most challenging energy situation, it opens the possibility for applying these same principles at higher energies—including at a possible future Electron-Ion Collider,” he said.

    Conquering challenges

    3
    A schematic of the LEReC system, which includes many significant advances in accelerator science. When light from a laser setup outside the RHIC tunnel strikes the photocathode of a unique direct current (DC) photocathode gun, it produces bunches of electrons that are then accelerated by a superconducting radiofrequency (SRF) cavity and transported into cooling sections of RHIC. Here the cold electrons are precisely matched with RHIC’s ion bunches in one RHIC ring, then the other, to extract heat and keep the ions tightly packed with the aim of maximizing collision rates.

    The accomplishment builds on an idea invented just over 50 years ago by Russian physicist Gersh Budker—namely, using a beam of electrons (which are inherently cooler than larger particles moving at the same speed) to extract heat from a beam of larger particles. This keeps the particles tightly packed and more likely to collide. But the Brookhaven version includes a series of first-in-the-world achievements and innovations even experts in the field doubted could succeed so quickly.

    “There were many physics and engineering challenges to overcome,” Fedotov noted.

    The team had to build and commission a new state-of-the-art electron accelerator that would fit inside the RHIC tunnel—which included using more compact radiofrequency (RF) acceleration technology rather than the standard direct-current (DC) method used in all previous electron-cooling setups. And because RHIC’s ions circulate as periodic bunches of particles, not a continuous stream, the electrons had to be produced in pulses that matched up with those bunches—not just in timing but also in energy and trajectory—all while maintaining their intrinsic coolness. Plus, because RHIC is really two accelerators, with ion beams moving in opposite directions in two beampipes, the physicists had to figure out how to cool both beams with the same stream of electrons!

    “Otherwise we would have had to build two of these electron accelerators,” Fedotov said.

    “It’s actually a huge installation made of many complex components, including 100 meters of beamline where the accelerated electrons propagate with the ions in one RHIC beam to extract their heat, then make a 180-degree turn to cool the ions of the other RHIC beam moving in the opposite direction. That has never been done before!”

    Generating electrons

    4
    Joseph Tuozzolo, the head engineer for the LEReC project, stands next to a warm radiofrequency cavity used in the project.

    To generate and rapidly accelerate these precision electron bunches, the team used a laser-activated photocathode electron gun followed by an accelerating RF cavity. The gun uses a high-frequency high-power laser and Brookhaven-designed photocathodes that are transported 12-at-a-time in a vacuum chamber from Brookhaven’s Instrumentation Division to the RHIC tunnel. Once at RHIC, the vacuum chamber can rotate like a Ferris wheel to switch out photocathodes as they wear out while RHIC is running, enabling the gun to run at high current for long-term operation when access to RHIC is limited.

    “When we first talked about this design, in 2015, this was only a drawing!” Fedotov said. “Now we are routinely using it.”

    The green laser that triggers the photocathodes to emit pulses of electrons is also the first of its kind—the highest average power green laser ever generated by a single fiber-based laser. Precision alignment and trimming of the laser pulses controls the frequency of the electron bunches generated for cooling.

    5
    Members of Collider-Accelerator Department vacuum group next to the cathode insertion device (l to r): Mike Nicoletta, Kirk Sinclair, and Ken Decker.

    The laser and photocathode gun produced the first electron pulses in May 2017. Then, after commissioning the first seven meters of beamline (the injector for the accelerator) at end of 2017, the team installed 100 meters of beamline, including five RF cavities and straight cooling sections covered by several layers of magnetic shielding, in January 2018. They then spent last year commissioning the full electron accelerator.

    Keeping it cool

    “The main challenge was delivering a beam with all the properties required for cooling—meaning small relative velocities in all directions, with matching energies and small angles—and then propagating this very low-energy electron beam along 100 meters of beam transport line while maintaining those properties,” said Dmitry Kayran, the accelerator physicist who led the commissioning effort.

    6
    Brookhaven Lab engineer Jean Clifford Brutus next to a deflecting radiofrequency cavity he helped to design and install for the LEReC project.

    Kayran described the work on simulations that went into optimizing beam parameters, which guided the installation of beam-monitoring instruments, which in turn determined the placement of the RF acceleration cavities.

    “Due to acceleration, beam quality can deteriorate, so you need this monitoring and careful adjustments to keep the energy spread as low as possible,” Kayran said.

    “Design of the cooling sections for Low-Energy RHIC electron Cooling (LEReC) is unique,” said accelerator physicist Sergei Seletskiy, who led that part of the effort. “Preserving beam quality in these cooling sections of both RHIC rings is a challenge, and again something that’s been demonstrated for the first time with this project.

    “Many unique features and challenges of our project are related to the fact that, for the first time in 50 years, we are applying electron cooling directly at ion-collision energy,” he noted. “Seeing all this tying together and working to cool ions with bunched electron beams and in two collider rings at once is amazing. This is a big achievement in accelerator physics!”

    7
    Collider-Accelerator Department engineers and technicians with high-tech custom electronics equipment required for successful beam operations (from rear, l to r): Loralie Smart, Linh Nguyen, Kayla Hernandez, Geetha Narayan, Zeynep Altinbas, Theodoro Samms.

    The next step will be to show that the cooling enhances collision rates in next year’s RHIC low-energy collisions—and then extracting the data and what they reveal about the building blocks of matter.

    With a bunched-beam electron cooling technique now experimentally demonstrated at Brookhaven Lab, its application to high-energy cooling can open new possibilities by producing high-quality hadron beams that are required for several future accelerator physics projects, including the proposed Electron-Ion Collider (EIC).

    LEReC was funded by the DOE Office of Science and benefitted from the help and expertise of many in Brookhaven Lab’s Collider-Accelerator Department and Instrumentation Division, as well as contributions from Fermi National Accelerator Laboratory, Argonne National Laboratory, Thomas Jefferson National Accelerator Facility, and Cornell University.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 12:54 pm on May 10, 2019 Permalink | Reply
    Tags: , “Belle II will accumulate more than 50 times the data sample of the original Belle experiment at KEK”, “We are developing the data-distribution software working not only with Belle II colleagues but also with colleagues at CERN., “We store an entire copy of the Belle II data and we have the computing resources to process that data and make it available to collaborators around the world”, , Belle II detector, Benefitting from our own experience at the RHIC & ATLAS Computing Center, BNL, Brookhaven’s magnet division constructed 43 custom-designed corrector magnets., , , , Physicists and engineers in the Laboratory’s Superconducting Magnet Division made contributions essential to upgrading the KEK accelerator helping to transform it into SuperKEKB., Physicists will search for signs of “new physics”—something that cannot be explained by the particles and forces already included in the Standard Model., , SuperKEKB accelerator, SuperKEKB collides electrons with their antimatter counterparts known as positrons, The corrector magnets are installed on each side of the Belle II detector   

    From Brookhaven National Lab: “Brookhaven Lab and the Belle II Experiment” 

    From Brookhaven National Lab

    May 7, 2019
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    Tracking particle smashups and detector conditions from half a world away, scientists seek answers to big physics mysteries.

    1
    SuperKEKB accelerator and Belle II detector at the interaction region.(Credit: Belle II/KEK)

    If you think keeping track of the photos on your mobile phone is a challenge, imagine how daunting the job would be if your camera were taking thousands of photos every second. That’s the task faced by particle physicists working on the Belle II experiment at Japan’s SuperKEKB particle accelerator, which started its first physics run in late March. Belle II physicists will sift through “snapshots” of millions of subatomic smashups per day—as well as data on the conditions of the “camera” at the time of each collision—to seek answers to some of the biggest questions in physics.

    A key part of the experiment is taking place half a world away, using computing resources and expertise at the U.S. Department of Energy’s Brookhaven National Laboratory, the lead laboratory for U.S. collaborators on Belle II.

    “We store an entire copy of the Belle II data, and we have the computing resources to process that data and make it available to collaborators around the world,” said Benedikt Hegner, a physicist in Brookhaven Lab’s Computational Sciences Initiative. To date, Brookhaven’s Scientific Data and Computing Center (SDCC) has handled up to 95 percent of the experiment’s entire computing workload—reconstructing particles from simulated events prior to the experiment’s startup, and since late March, from live collision events. SDCC will continue that role for the experiment’s first three years, thereafter maintaining some 30 percent of the data-transfer and storage responsibility while transitioning the rest to other Belle II member nations that have powerful GRID computing capabilities.

    “We are developing the data-distribution software, working not only with Belle II colleagues but also with colleagues at CERN, the European laboratory for particle physics research, learning from their experience managing datasets from the Large Hadron Collider (LHC)—as well as our own experience at the RHIC & ATLAS Computing Center,” Hegner said.

    2
    Benedikt Hegner in the Scientific Data and Computing Center at Brookhaven Lab, which stores and processes Belle II data and makes it available to collaborators around the world.

    Brookhaven also hosts Belle II’s “conditions database”—an archive of the detector’s conditions at the time of each recorded collision. This database tracks millions of variables—for example, the detector’s level of electronic noise, millimeter-scale movements of the detector due to the strong magnetic field, and variations in electronic response due to small temperature changes—all of which need to be properly taken into account to make sense of Belle II’s measurements.

    “This is the first time a particle physics experiment’s conditions database is being hosted at a distant location,” Hegner noted. Tracking the conditions helps calibrate the detector and even feeds input to the “trigger” systems that decide which collisions to record. “If we’re having trouble with our system, Belle II will eventually see that during data collection. So, the reliability of our services is essential,” Hegner said.

    But Brookhaven’s involvement in Belle II goes beyond cataloging collisions and crunching the numbers. Physicists and engineers in the Laboratory’s Superconducting Magnet Division made contributions essential to upgrading the KEK accelerator, helping to transform it into SuperKEKB, and members of Brookhaven Lab’s physics department are looking forward to analyzing Belle II data and being part of the upgraded facility’s discoveries.

    Improved magnets, more collisions, “new physics”?

    Like its predecessor, SuperKEKB collides electrons with their antimatter counterparts, known as positrons. To keep collision rates high, these beams must be tightly focused. But the magnetic fields guiding the particles in one beam can have unwanted effects in the adjacent beam, causing the particles to spread. To fine-tune the fields of the accelerator magnets and counteract these adjacent-beam effects, Brookhaven’s magnet division constructed 43 custom-designed corrector magnets. These corrector magnets are installed on each side of the Belle II detector, making adjustments to both the incoming and outgoing beams to maintain high beam intensity, or “luminosity.” High luminosity results in higher collision rates, so physicists at Brookhaven and around the world will have more data to analyze.

    4
    Corrector magnets: Leak field cancel coil being wound by Brookhaven Lab magnet division technician Thomas Van Winckel.

    “Belle II will accumulate more than 50 times the data sample of the original Belle experiment at KEK,” said Brookhaven physicist David Jaffe, who is coordinating Brookhaven Lab scientists’ involvement in the project.

    By scouring reconstructed images of the particles emerging from these electron-positron collisions, physicists will search for signs of “new physics”—something that cannot be explained by the particles and forces already included in the Standard Model, the world’s reigning (and well-tested) theory of particle physics.

    One particular area of interest is the decay of beauty and charm mesons—particles made of two quarks, one of which is a heavy “beauty” or “charm” quark. These “heavy flavor” mesons are created in abundance in electron-positron collisions at the SuperKEKB accelerator.

    “SuperKEKB is called a ‘B factory’ because it is optimized for the production of beauty mesons. It also produces an abundance of charm mesons,” Jaffe said. “While many physicists on Belle II will be investigating the behavior of beauty mesons, the Brookhaven team will be exploiting the huge sample of charm mesons to look for possible discoveries.”

    For example, if heavy flavor mesons measured by Belle II decay (transform into other particles) differently than predicted by the Standard Model, such a discrepancy would be an indication that some new, previously undiscovered particle might be taking part in the action.

    Evidence of new particles might help account for the mysterious dark matter that makes up some 27 percent of the universe, or offer clues about dark energy, which accounts for another 68 percent (with the remaining 5 percent made of the ordinary matter we see around us). Such a discovery might also help explain why today’s universe is made of matter rather than a mix of matter and antimatter, even though scientists believe both were created in equal amounts at the very beginning of time.

    To grasp how shocking this matter-antimatter asymmetry is, think of the common laundry experience of losing a random sock in the dryer. But imagine if every time you did the laundry—even a billion loads, each with a billion pairs of socks labeled “left” and “right”—you always ended up with a single unpaired left sock and never a lone right sock. That’s what it’s like for physicists trying to understand why the universe ended up with only matter. There must be some difference in the way matter and antimatter behave to explain this anomaly.

    There is evidence that matter and antimatter behave differently from several well-known experiments studying meson decays. These include a Nobel Prize-winning experiment at Brookhaven’s Alternating Gradient Synchrotron, which studied the decay of mesons containing a strange quark in the 1960s. More recently, several experiments studying beauty meson decays at other B factories—the original Belle at KEK, the BaBar experiment at the SLAC National Accelerator Laboratory in the U.S., and the LHCb experiment at CERN—observed similar asymmetries. But thus far, the matter-antimatter asymmetry observed in beauty and strange mesons follows the pattern predicted by the Standard Model, and is not sufficient to explain the matter-antimatter asymmetry of the universe.

    LHCb also recently observed a smaller level of matter-antimatter asymmetry in charm meson decays for the first time. It is unclear if this new observation is consistent with the Standard Model or due to new particles that preferentially interact with charm quarks. Additional measurements are needed to solve this mystery.

    5
    Physicist David Jaffe is coordinating Brookhaven Lab’s contributions to Belle II.

    “What we’ll do at Belle II is like many, many trips to the laundromat where we carefully launder our `charmed’ socks and use different methods to dry them. We’ll use our observations from these different loads of charmed laundry to map out what happens in charm meson decays to higher precision than ever before,” explained Jaffe. “Then we’ll compare those observations to our expectations from the Standard Model to see if we’ve found evidence for new particles.”

    The Belle II experiment, Jaffe noted, complements LHCb. “Belle II has a different range of features that enable contrasting studies of the charm mesons,” he said. “We are starting to accumulate large data samples to help us make the precision measurements we need to resolve these questions. Once we’ve confirmed the technical capabilities of the experiment, we will move on to data analysis and the possibility of discovery.”

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 12:22 pm on May 10, 2019 Permalink | Reply
    Tags: , , BNL, , , ,   

    From Brookhaven National Lab: “New Approach for Solving Protein Structures from Tiny Crystals” 

    From Brookhaven National Lab

    May 3, 2019
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer,
    genzer@bnl.gov
    (631) 344-3174

    Technique opens door for studies of countless hard-to-crystallize proteins involved in health and disease.

    1
    Wuxian Shi, Martin Fuchs, Sean McSweeney, Babak Andi, and Qun Liu at the FMX beamline at Brookhaven Lab’s National Synchrotron Light Source II [see below], which was used to determine a protein structure from thousands of tiny crystals.

    Using x-rays to reveal the atomic-scale 3-D structures of proteins has led to countless advances in understanding how these molecules work in bacteria, viruses, plants, and humans—and has guided the development of precision drugs to combat diseases such as cancer and AIDS. But many proteins can’t be grown into crystals large enough for their atomic arrangements to be deciphered. To tackle this challenge, scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and colleagues at Columbia University have developed a new approach for solving protein structures from tiny crystals.

    The method relies on unique sample-handling, signal-extraction, and data-assembly approaches, and a beamline capable of focusing intense x-rays at Brookhaven’s National Synchrotron Light Source II (NSLS-II)—a DOE Office of Science user facility—to a millionth-of-a-meter spot, about one-fiftieth the width of a human hair.

    “Our technique really opens the door to dealing with microcrystals that have been previously inaccessible, including difficult-to-crystallize cell-surface receptors and other membrane proteins, flexible proteins, and many complex human proteins,” said Brookhaven Lab scientist Qun Liu, the corresponding author on the study, which was published on May 3 in IUCrJ, a journal of the International Union of Crystallography.

    Deciphering protein structures

    Protein crystallography has been a dominant method for solving protein structures since 1958, improving over time as x-ray sources have grown more powerful, allowing more precise structure determinations. To determine a protein structure, scientists measure how x-rays like those generated at NSLS-II diffract, or bounce off, the atoms in an ordered crystalline lattice consisting of many copies of the same protein molecule all arrayed the same way. The diffraction pattern conveys information about where the atoms are located. But it’s not sufficient.

    2
    A cartoon representing the structure of a well-studied plant protein that served as a test case for the newly developed microcrystallography technique. Magenta mesh patterns surrounding sulfur atoms intrinsic to the protein (yellow spheres) indicate the anomalous signals that were extracted using low-energy x-ray diffraction of thousands of crystals measuring less than 10 millionths of a meter, the size of a bacterium.

    “Only the amplitudes of diffracted x-ray ‘waves’ are recorded on the detector, but not their phases (the timing between waves),” said Liu. “Both are required to reconstruct a 3-D structure. This is the so-called crystallographic phase problem.”

    Crystallographers have solved this problem by collecting phase data from a different kind of scattering, known as anomalous scattering. Anomalous scattering occurs when atoms heavier than a protein’s main components of carbon, hydrogen, and nitrogen absorb and re-emit some of the x-rays. This happens when the x-ray energy is close to the energy those heavy atoms like to absorb. Scientists sometimes artificially insert heavy atoms such as selenium or platinum into the protein for this purpose. But sulfur atoms, which appear naturally throughout protein molecules, can also produce such signals, albeit weaker. Even though these anomalous signals are weak, a big crystal usually has enough copies of the protein with enough sulfur atoms to make them measurable. That gives scientists the phase information needed to pinpoint the location of the sulfur atoms and translate the diffraction patterns into a full 3-D structure.

    “Once you know the sulfur positions, you can calculate the phases for the other protein atoms because the relationship between the sulfur and the other atoms is fixed,” said Liu.

    But tiny crystals, by definition, don’t have that many copies of the protein of interest. So instead of looking for diffraction and phase information from repeat copies of a protein in a single large crystal, the Brookhaven/Columbia team developed a way to take measurements from many tiny crystals, and then assemble the collective data.

    Tiny crystals, big results

    To handle the tiny crystals, the team developed sample grids patterned with micro-sized wells. After pouring solvent containing the microcrystals over these well-mount grids, the scientists removed the solvent and froze the crystals that were trapped on the grids.

    3
    Micro-patterned sample grids for manipulation of microcrystals.

    “We still have a challenge, though, because we can’t see where the tiny crystals are on our grid,” said Liu. “To find out, we used microdiffraction at NSLS-II’s Frontier Microfocusing Macromolecular Crystallography (FMX) beamline to survey the whole grid. Scanning line by line, we can find where those crystals are hidden.”

    As Martin Fuchs, the lead beamline scientist at FMX, explained, “The FMX beamline can focus the full intensity of the x-ray beam down to a size of one micron, or millionth of a meter. We can finely control the beam size to match it to the size of the crystals—five microns in the case of the current experiment. These capabilities are crucial to obtain the best signal,” he said.

    Wuxian Shi, another FMX beamline scientist, noted that “the data collected in the grid survey contains information about the crystals’ location. In addition, we can also see how well each crystal diffracts, which allows us to pick only the best crystals for data collection.”

    The scientists were then able to maneuver the sample holder to place each mapped out microcrystal of interest back in the center of the precision x-ray beam for data collection.

    They used the lowest energy available at the beamline—tuned to approach as closely as possible sulfur atoms’ absorption energy—and collected anomalous scattering data.

    “Most crystallographic beamlines could not reach the sulfur absorption edge for optimized anomalous signals,” said co-author Wayne Hendrickson of Columbia University. “Fortunately, NSLS-II is a world-leading synchrotron light source providing bright x-rays covering a broad spectrum of x-ray energy. And even though our energy level was slightly above the ideal absorption energy for sulfur, it generated the anomalous signals we needed.”

    But the scientists still had some work to do to extract those important signals and assemble the data from many tiny crystals.

    “We are actually getting thousands of pieces of data,” said Liu. “We used about 1400 microcrystals, each with its own data set. We have to put all the data from those microcrystals together.”

    4
    Scientists used a five-micron x-ray beam at the FMX beamline at NSLS-II to scan the entire grid and locate the tiny invisible crystals. Then a heat map (green) was used to guide the selection of positions for diffraction data acquisition.

    They also had to weed out data from crystals that were damaged by the intense x-rays or had slight variations in atomic arrangements.

    “A single microcrystal does not diffract x-rays sufficiently for structure solution prior to being damaged by the x-rays,” said Sean McSweeney, deputy photon division director and program manager of the Structural Biology Program at NSLS-II. “This is particularly true with crystals of only a few microns, the size of about a bacterial cell. We needed a way to account for that damage and crystal structure variability so it wouldn’t skew our results.”

    They accomplished these goals with a sophisticated multi-step workflow process that sifted through the data, discarded outliers that might have been caused by radiation damage or incompatible crystals, and ultimately extracted the anomalous scattering signals.

    “This is a critical step,” said Liu. “We developed a computing procedure to assure that only compatible data were merged in a way to align the individual microcrystals from diffraction patterns. That gave us the required signal-to-noise ratios for structure determination.”

    Applying the technique

    This technique can be used to determine the structure of any protein that has proven hard to crystallize to a large size. These include cell-surface receptors that allow cells of advanced lifeforms such as animals and plants to sense and respond to the environment around them by releasing hormones, transmitting nerve signals, or secreting compounds associated with cell growth and immunity.

    “To adapt to the environment through evolution, these proteins are malleable and have lots of non-uniform modifications,” said Liu. “It’s hard to get a lot of repeat copies in a crystal because they don’t pack well.”

    In humans, receptors are common targets for drugs, so having knowledge of their varied structures could help guide the development of new, more targeted pharmaceuticals.

    But the technique is not restricted to just small crystals.

    “The method we developed can handle small protein crystals, but it can also be used for any size protein crystals, any time you need to combine data from more than one sample,” Liu said.

    This research was supported in part by Brookhaven National Laboratory’s “Laboratory Directed Research and Development” program and the National Institutes of Health (NIH) grant GM107462. The NSLS-II at Brookhaven Lab is a DOE Office of Science user facility (supported by DE-SC0012704), with beamline FMX supported primarily by the National Institute of Health, National Institute of General Medical Sciences (NIGMS) through a Biomedical Technology Research Resource P41 grant (P41GM111244), and by the DOE Office of Science.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 9:03 am on May 4, 2019 Permalink | Reply
    Tags: , , BNL, Lisa Miller, ,   

    From Brookhaven National Lab: Women n STEM- “Meet NSLS-II’s Lisa Miller” 

    From Brookhaven National Lab

    May 1, 2019
    Stephanie Kossman
    skossman@bnl.gov

    1
    As the manager of NSLS-II’s USCEO office, Lisa Miller can usually be found traveling around the facility’s experimental floor on trike—the most fun (and the safest) way to quickly get around NSLS-II’s half-mile ring.

    When Lisa Miller isn’t managing outreach efforts at the National Synchrotron Light Source II (NSLS-II) [image s below], she’s using the facility’s ultrabright x-ray light to study neurological protein-misfolding diseases, such as Alzheimer’s disease.

    Today, Miller is the manager of NSLS-II’s user services, communications, education, and outreach (USCEO) office, but she first came to the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory 25 years ago as a doctoral student at NSLS, the predecessor of NSLS-II—a DOE Office of Science User Facility at Brookhaven.

    “My thesis advisor came to NSLS all the time,” Miller said. “He would send a team of four students and we would spend a lot of time collecting each other’s data. I always got the night shift.”

    Having developed a passion for scientific collaboration and helping others collect their data, Miller decided to come back to NSLS for a postdoctoral research project—building an infrared beamline (experimental station) for biological research.

    2
    When Lisa Miller isn’t managing outreach efforts at NSLS-II, she’s using the facility’s ultrabright x-ray light to study neurological protein-misfolding diseases, such as Alzheimer’s disease.

    “And I’ve been here ever since,” she said. “After my postdoc, I ran two infrared beamlines at NSLS for 15 years.”

    Growing up, Miller and her three younger sisters were always encouraged to follow whatever career path they wanted. “Being a girl didn’t matter,” she said. “My dad taught us to drive a tractor, change the oil in the car, and fix the leaky sink. We got tools for our birthdays.”

    Of the four girls, Miller was the only one to become a scientist. “I always knew I liked science, but I never imagined working at a synchrotron light source,” she said. “I wanted to get a faculty job in a four-year undergraduate institution and teach. Research was a secondary thing to me. But in my early years at NSLS, I had such supportive mentors. All of the beamline scientists were so willing to help me succeed that, after a year, I had no desire to look for a faculty position.”

    During her time at NSLS and NSLS-II, Miller has been researching “protein-misfolding” diseases like Alzheimer’s disease, in which normal proteins in the brain clump together to form “plaques” and cause neurodegeneration—the death of brain cells.

    “We used the x-ray and infrared microscopes at NSLS to show that these plaques are loaded with metal ions like copper and zinc,” Miller said. “These metals are nutritionally essential, but they’re not supposed to be in the plaques. We’ve hypothesized that the metals can cause toxic reactions in the brain, leading to cell death. Now we are trying to figure out how and why this happens.”

    To move the field forward, Miller is developing new research methods that use the advanced capabilities of NSLS-II.

    “NSLS-II is a huge improvement for my research, especially in terms of the spatial resolution it provides,” she said. “Now we have these really tiny x-ray beams that enable us to image individual parts of the cells, including cell membranes, in order to understand how the metal ions are transported into the cells and damage them. The suite of imaging beamlines that we have here at NSLS-II enables us to study the problem from the level of the brain tissue all the way down to individual molecules in the cells.”

    Throughout her years of research, Miller retained her interest in science education. In 2001, she was asked to lead NSLS’s information and outreach office. Then, once NSLS-II was established, she became the facility’s first manager of USCEO.

    “Continuing my research is a really important part of my career, but that includes sharing my passion for science through teaching and outreach,” she said. As an adjunct associate professor in chemistry and biomedical engineering at Stony Brook University, Miller mentors doctoral students in synchrotron science. “Their generation will figure out the next cool things that synchrotrons can do.”

    Miller’s outreach efforts extend to the visiting researcher, or “user,” program that she oversees at NSLS-II.

    “My goal is for the users at NSLS-II to have a “Disneyland” user experience—to be able to do top-notch research, from conceiving the idea to doing the experiments and publishing the work, and having us support that. It’s more than just the photons; it’s everything from the registration process to comfortable accommodations and good coffee.”

    From the visiting researchers to the beamline scientists and support staff, Miller says having the chance to interact with so many different people is her favorite part of working at the light source.

    “We have a tremendous variety of personalities and a melting pot of people from all over the world,” she said. “The synchrotron community is a really welcoming and collaborative environment to be in.”

    As much as Miller likes working at NSLS-II, she stresses the importance of a work-life balance. Outside of “the office,” you can find Miller on backpacking trips around the country and the world. She’s hiked to the high points of 49 states, backpacked over 600 miles of the Appalachian Trail, and climbed Mount Kilimanjaro in Africa.

    Miller earned a Ph.D. in biophysics from Albert Einstein College of Medicine in 1995 and an M.S. in Chemistry from Georgetown University in 1992.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 2:29 pm on April 26, 2019 Permalink | Reply
    Tags: "New Lens System for Brighter Sharper Diffraction Images", "The team used a photocathode gun that generates the electrons through a process called photoemission”, , “We made the sample by depositing the gold atoms on a several nanometer thick carbon film using a technique called thermal evaporation”, BNL, Brookhaven’s Accelerator Test Facility, , Electron beam-related research techniques, , , , The researchers used two groups of four quadrupole magnets to tune the electron beam., Ultra-fast electron diffraction imaging   

    From Brookhaven National Lab: “New Lens System for Brighter, Sharper Diffraction Images” 

    From Brookhaven National Lab

    April 25, 2019

    Cara Laasch
    laasch@bnl.gov
    (631) 344-8458

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Researchers from Brookhaven Lab designed, implemented, and applied a new and improved focusing system for electron diffraction measurements.

    1
    Mikhail Fedurin, Timur Shaftan, Victor Smalyuk, Xi Yang, Junjie Li, Lewis Doom, Lihua Yu, and Yimei Zhu are the Brookhaven team of scientists that realized and demonstrated the new lens system for as ultra-fast electron diffraction imaging.

    To design and improve energy storage materials, smart devices, and many more technologies, researchers need to understand their hidden structure and chemistry. Advanced research techniques, such as ultra-fast electron diffraction imaging can reveal that information. Now, a group of researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new and improved version of electron diffraction at Brookhaven’s Accelerator Test Facility (ATF)—a DOE Office of Science User Facility that offers advanced and unique experimental instrumentation for studying particle acceleration to researchers from all around the world. The researchers published their findings in Scientific Reports, an open-access journal by Nature Research.

    Advancing a research technique such as ultra-fast electron diffraction will help future generations of materials scientists to investigate materials and chemical reactions with new precision. Many interesting changes in materials happen extremely quickly and in small spaces, so improved research techniques are necessary to study them for future applications. This new and improved version of electron diffraction offers a stepping stone for improving various electron beam-related research techniques and existing instrumentation.

    “We implemented our new focusing system for electron beams and demonstrated that we can improve the resolution significantly when compared to the conventional solenoid technique,” said Xi Yang, author of the study and an accelerator physicist at the National Synchrotron Light Source II (NSLS-II) [see below], a DOE Office of Science User Facility at Brookhaven Lab. “The resolution mainly depends on the properties of light – or in our case – of the electron beam. This is universal for all imaging techniques, including light microscopy and x-ray imaging. However, it is much more challenging to focus the charged electrons to a near-parallel pencil-like beam at the sample than it would be with light, because electrons are negatively charged and therefore repulse one another. This is called the space charge effect. By using our new setup, we were able to overcome the space charge effect and obtain diffraction data that is three times brighter and two times sharper; it’s a major leap in resolution.”

    2
    The colorful images are four different electron diffraction measurements at ATF. The left column shows diffraction patterns of the sample using the newly developed quadrupoles, while the right column shows diffraction patterns without the new lens system. In the left column the rings of the pattern are sharper, rounder and turn red, which means that the overall resolution of the measurement is higher.

    Every electron diffraction setup uses an electron beam that is focused on the sample so that the electrons bounce off the atoms in the sample and travel further to the detector behind the sample. The electrons create a so-called diffraction pattern, which can be translated into the structural makeup of the materials at the nanoscale. The advantage of using electrons to image this inner structure of materials is that the so called diffraction limit of electrons is very low, which means scientists can resolve smaller details in the structure compared to other diffraction methods.

    A diverse team of researchers was needed to improve such a complex research method. The Brookhaven Lab team consisted of electron beam experts from the NSLS-II, electron accelerator experts from ATF, and materials science experts from the condensed matter physics & materials science (CMPMS) department.

    “This advance would not have been possible without the combination of all our expertise across Brookhaven Lab. At NSLS-II, we have expertise on how to handle the electron beam. The ATF group brought the expertise and capabilities of the electron gun and laser technologies – both of which were needed to create the electron beam in the first place. And the CMPMS group has the sample expertise and, of course, drives the application needs. This is a unique synergy and, together, we were able to show how the resolution of the technique can be improved drastically,” said Li Hua Yu, NSLS-II senior accelerator physicist and co-author of the study.

    To achieve its improved resolution, the team developed a different method of focusing the electron beam. Instead of using a conventional approach that involves solenoid magnets, the researchers used two groups of four quadrupole magnets to tune the electron beam. Compared to solenoid magnets, which act as just one lens to shape the beam, the quadrupole magnets work like a specialized lens system for the electrons, and they gave the scientists far more flexibility to tune and shape the beam according to the needs of their experiment.

    “Our lens system can provide a wide range of tunability of the beam. We can optimize the most important parameters such as beam size, or charge density, and beam divergence based on the experimental conditions, and therefore provide the best beam quality for the scientific needs,” said Yang.

    The team can even adjust the parameters on-the-fly with online optimization tools and correct any nonuniformities of the beam shape; however, to make this measurement possible, the team needed the excellent electron beam that ATF provides. ATF has an electron gun that generates an extremely bright and ultrashort electron beam, which offers the best conditions for electron diffraction.

    “The team used a photocathode gun that generates the electrons through a process called photoemission,” said Mikhail Fedurin, an accelerator physicist at ATF. “We shoot an ultrashort laser pulse into a copper cathode, and when the pulse hits the cathode a cloud of electrons forms over the copper. We pull the electrons away using an electric field and then accelerate them. The amount of electrons in one of these pulses and our capability to accelerate them to specific energies make our system attractive for material science research – particularly for ultrafast electron diffraction.”

    The focusing system together with the ATF electron beam is very sensitive, so the researchers can measure the influences of Earth’ magnetic field on the electron beam.

    “In general, electrons are always influenced by magnetic fields—this is how we steer them in particle accelerators in the first place; however, the effect of Earth’s magnetic field is not negligible for the low-energy beam we used in this experiment,” said Victor Smalyuk, NSLS-II accelerator physics group leader and co-author of the study. “The beam deviated from the desired trajectory, which created difficulties during the initial starting phase, so we had to correct for this effect.”

    Beyond the high brightness of the electron beam and the high precision of the focusing system, the team also needed the right sample to make these measurements. The CMPMS group provided the team with a polycrystalline gold film to fully explore the newly designed lens system and to put it to the test.

    “We made the sample by depositing the gold atoms on a several nanometer thick carbon film using a technique called thermal evaporation,” said Junjie Li, a physicist in the CMPMS department. “We evaporated gold particles so that they condense on the carbon film and form tiny, isolated nanoparticles that slowly merge together and form the polycrystalline film.”

    This film was essential for the measurements because it has randomly oriented crystals that merge together. Therefore, the inner structure of the sample is not uniform, but consists of many differently oriented areas, which means that the diffraction pattern mainly depends on the electron beam qualities. This gives the scientists the best ground to really test their lens system, to tune the beam, and to see the impact of their tuning directly in the quality of the diffraction measurement.

    “We initially set out to improve electron diffraction for scientific studies of materials, but we also found that this technique can help us characterize our electron beam. In fact, diffraction is very sensitive to the electron beam parameters, so we can use the diffraction pattern of a known sample to measure our beam parameters precisely and directly, which is usually not that easy,” said Yang.

    The team intends to pursue further improvements, and they already have plans to develop another setup for ultra-fast electron microscopy to directly visualize a biological sample.

    “We hope to achieve ultrafast single-shot electron beam imaging at some point and maybe even make molecular movies, which isn’t possible with our current electron beam imaging setup,” said Yang.

    This research was supported by Laboratory Directed Research and Development funding and by DOE’s Office of Science through its support of the ATF.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

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