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  • richardmitnick 3:30 pm on June 29, 2017 Permalink | Reply
    Tags: , , , BNL NSLS II, , , neutral sphingomyelinase (nSMase2) allow cancer cells to pass DNA and proteins to other cells to change their behavior, Stony Brook U   

    From Stony Brook: “Researchers Define Structure of Key Enzyme Implicated in Cancer, Neurological Disease” 

    Stoney Brook bloc

    Stoney Brook

    Jun 29, 2017
    No writer credit found

    1
    Stony Brook-led research into the structure of a key enzyme involved with cell growth regulation could offer important clues to understanding cancer and neurodegenerative diseases, including Alzheimer’s disease. The finding, published in PNAS, reveals the first visualization of the enzyme and could provide insight into how the enzyme is activated.

    The enzyme, neutral sphingomyelinase (nSMase2), is one of the major enzymes that produces ceramide in the body. Ceramides are oil-like lipids that are produced in response to chemotherapy and other cell stresses. The ceramides that nSMase2 produces allow cancer cells to pass DNA and proteins to other cells to change their behavior. This plays a significant role in aiding the cancerous cells to spread into other regions as ceramides are produced. With this first visual of the structure of the enzyme, the researchers hope to understand how to de-activate the enzyme. Information on de-activating the enzyme could lead to a way to design cancer drugs that inhibit nSMase2.

    The different colors of this structural visualization of nSMase2 indicate parts of the enzyme that may change their shape when the protein is switched ‘on,’ encouraging cancer cells to spread.

    “Our finding is promising because the way in which we determined the structure reveals an unexpected mechanism for how nSMase2 is activated to generate ceramide,” said Mike Airola, PhD, Assistant Professor of Biochemistry and Cell Biology and lead author. To obtain this structure, the researchers screened thousands of different samples to have this protein form very small crystals that could be captured visually via X-rays. These X-rays bounce off the protein, and based on the angle of movements they calculated what structure looks like.

    Once they defined structure in this way, the research team made hypotheses as to how the shape of this important enzyme changes in order to be activated and then tested these hypotheses. Their findings suggested the same region that kept nSMase2 off was crucial for turning it on.

    The researchers determined the enzyme consists of two parts: one that partitions inside the oil-like membrane and one that soluble in water. Their work with the structure revealed that to turn nSMase2 ‘on,’ these two parts come together to switch the enzyme from off to on. They found that by removing some of these parts, they were able to obtain a picture of the enzyme trapped in its ‘off’ state. Using the structure, Dr. Airola and colleagues added back different parts of the enzyme, and then they were able to turn it back on to its on, or activated state.

    Dr. Airola explained that while much is known about the cellular functions of nSMase2, there is limited scientific knowledge into the molecular mechanisms regulating its activity. This latest research presents the crystal structure of the enzyme and enabled the researchers to understand its molecular mechanism to a level not known before.

    The next step in their research is to get a picture of the enzyme in its activated ‘on’ state. They are also working to identify new scaffolds that could be used as drugs to inhibit this enzyme. Their long-term goal is to understand how this enzyme is turned on and stop it from working as potential therapeutic strategy.

    Co-authors on the paper include Stony Brook University researchers Lina M. Obeid, Yusuf A. Hannun and Can E. Senkal of the Stony Brook University Cancer Center; Miguel Garcia-Diaz and Kip Guja of the Department of Pharmacological Sciences; Prajna Shanbhogue and Rohan Maini of the Department of Biochemistry and Cell Biology; Achraf Shamseddine of the Department of Medicine; and Nana Bartke and Bill X. Wu of the Medical University of South Carolina.

    The research was supported in part by the National institutes of Health. Some of the research was completed with access to the facilities at the Synchrotron Light Source and Brookhaven National Laboratory.

    BNL NSLS-II


    BNL NSLS-II

    See the full article here .

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    Stoney Brook campus

    Stony Brook’s reach extends from its 1,039-acre campus on Long Island’s North Shore–encompassing the main academic areas, an 8,300-seat stadium and sports complex and Stony Brook Medicine–to Stony Brook Manhattan, a Research and Development Park, four business incubators including one at Calverton, New York, and the Stony Brook Southampton campus on Long Island’s East End. Stony Brook also co-manages Brookhaven National Laboratory, joining Princeton, the University of Chicago, Stanford, and the University of California on the list of major institutions involved in a research collaboration with a national lab.

    And Stony Brook is still growing. To the students, the scholars, the health professionals, the entrepreneurs and all the valued members who make up the vibrant Stony Brook community, this is a not only a great local and national university, but one that is making an impact on a global scale.

     
  • richardmitnick 10:24 am on June 23, 2017 Permalink | Reply
    Tags: , , , BNL NSLS II, Bragg Projection Ptychography, Crystal lattice of nanoscale materials, Hard X-ray Nanoprobe (HXN) beamline at NSLS-II, , Stephan Hruszkewycz,   

    From BNL- “National Synchrotron Light Source II User Profile: Stephan Hruszkewycz” 

    Brookhaven Lab

    June 19, 2017
    Laura Mgrdichian
    mgrdichian@gmail.com

    1
    Stephan Hruszkewycz. No image credit.

    Stephan Hruskewycz is an assistant physicist in the Materials Science Division at the U.S. Department of Energy’s (DOE) Argonne National Laboratory.

    While he regularly conducts research at Argonne’s own synchrotron user facility, the Advanced Photon Source (APS), his work on the nanoscale structure and behavior of materials has led him to book beamtime at the DOE’s newest synchrotron, the National Synchrotron Light Source II (NSLS-II). Both NSLS-II and APS are DOE Office of Science User Facilities.

    ANL APS


    ANL APS

    BNL NSLS-II


    BNL NSLS II

    What are you studying at NSLS-II?

    The focus of our NSLS-II experiments has been to image defects and imperfections in the crystal lattice of nanoscale materials using a new imaging technique known as Bragg Projection Ptychography. Specifically, we have been studying stacking faults in nanowires made of III-V semiconductors, a class of semiconductor that results from the combination of elements from column III on the periodic table (mainly aluminum, gallium, and indium) and column V (nitrogen, phosphorous, arsenic, and antimony). These materials have properties that make them excellent for certain applications; for example, solar cells made of III-V cells are very efficient.

    During our next run, we will be imaging strain fields in complex oxide thin-film nanostructures. These classes of materials have potential uses for energy conversion in solar and fuel cell applications, and their nanoscale structure plays a large role in performance. By studying these structures in detail, we may be able to figure out how to make these materials perform better.

    Why is NSLS-II is particularly suited to your work?

    The Hard X-ray Nanoprobe (HXN) beamline at NSLS-II delivers a coherent hard x-ray beam focused to a few tens of nanometers and the ability to rotate the sample and detector to enable Bragg diffraction with a nanofocused beam. We are capitalizing on the coherence and stability of the focused beam to convert a series of Bragg diffraction patterns measured from different overlapping positions of the sample into an image of the lattice structure inside a specific region of the crystal. The result provides an image with a resolution down to just a few nanometers, as well as picometer-level sensitivity to lattice distortions.

    Tell us about your background and how you arrived at this field of research.

    I have been interested for some time in developing new methods to exploit coherent hard x-rays to reveal of the structure and dynamics of materials. Recently, I have focused on applying these methods to materials with inhomogeneous internal lattice structures that dictate their overall properties, such as nanostructured oxide thin films and semiconductors. To me, this is an exciting area of research, one where cutting-edge materials science questions can be answered with new x-ray imaging methods at state-of-the-art synchrotron sources that deliver highly coherent beams.

    Who else is involved in this work?

    So far, I have been joined at NSLS-II by Megan Hill, a graduate student in Northwestern University’s Materials Science and Engineering Department; Martin Holt, a staff scientist in Argonne’s Center for Nanoscale Materials; and Brian Stephenson, a senior physicist in Argonne’s Materials Science Division.

    See the full article here .

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 10:06 am on June 23, 2017 Permalink | Reply
    Tags: , , BNL NSLS II, , , Improve the performance of fuel cells that run on hydrogen fuel but can be poisoned by CO, , Peking University, Taiyuan University of Technology China   

    From BNL: “New Efficient, Low-Temperature Catalyst for Converting Water and CO to Hydrogen Gas and CO2” 

    Brookhaven Lab

    June 22, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    Low-temperature “water gas shift” reaction produces high levels of pure hydrogen for potential applications, including fuel cells.

    1
    Brookhaven Lab chemists Ping Liu and José Rodriguez helped to characterize structural and mechanistic details of a new low-temperature catalyst for producing high-purity hydrogen gas from water and carbon monoxide. No image credit.

    Scientists have developed a new low-temperature catalyst for producing high-purity hydrogen gas while simultaneously using up carbon monoxide (CO). The discovery—described in a paper set to publish online in the journal Science on Thursday, June 22, 2017—could improve the performance of fuel cells that run on hydrogen fuel but can be poisoned by CO.

    “This catalyst produces a purer form of hydrogen to feed into the fuel cell,” said José Rodriguez, a chemist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory. Rodriguez and colleagues in Brookhaven’s Chemistry Division—Ping Liu and Wenqian Xu—were among the team of scientists who helped to characterize the structural and mechanistic details of the catalyst, which was synthesized and tested by collaborators at Peking University in an effort led by Chemistry Professor Ding Ma.

    Because the catalyst operates at low temperature and low pressure to convert water (H2O) and carbon monoxide (CO) to hydrogen gas (H2) and carbon dioxide (CO2), it could also lower the cost of running this so-called “water gas shift” reaction.

    “With low temperature and pressure, the energy consumption will be lower and the experimental setup will be less expensive and easier to use in small settings, like fuel cells for cars,” Rodriguez said.

    The gold-carbide connection

    The catalyst consists of clusters of gold nanoparticles layered on a molybdenum-carbide substrate. This chemical combination is quite different from the oxide-based catalysts used to power the water gas shift reaction in large-scale industrial hydrogen production facilities.

    “Carbides are more chemically reactive than oxides,” said Rodriguez, “and the gold-carbide interface has good properties for the water gas shift reaction; it interacts better with water than pure metals.”

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    Wenqian Xu and José Rodriguez of Brookhaven Lab and Siyu Yao, then a student at Peking University but now a postdoctoral research fellow at Brookhaven, conducted operando x-ray diffraction studies of the gold-molybdenum-carbide catalyst over a range of temperatures (423 Kelvin to 623K) at the National Synchrotron Light Source (NSLS) at Brookhaven Lab. The study revealed that at temperatures above 500K, molybdenum-carbide transforms to molybdenum oxide, with a reduction in catalytic activity. No image credit

    “The group at Peking University discovered a new synthetic method, and that was a real breakthrough,” Rodriguez said. “They found a way to get a specific phase—or configuration of the atoms—that is highly active for this reaction.”

    Brookhaven scientists played a key role in deciphering the reasons for the high catalytic activity of this configuration. Rodriguez, Wenqian Xu, and Siyu Yao (then a student at Peking University but now a postdoctoral research fellow at Brookhaven) conducted structural studies using x-ray diffraction at the National Synchrotron Light Source (NSLS) while the catalyst was operating under industrial or technical conditions.

    BNL NSLS

    These operando experiments revealed crucial details about how the structure changed under different operating conditions, including at different temperatures.

    With those structural details in hand, Zhijun Zuo, a visiting professor at Brookhaven from Taiyuan University of Technology, China, and Brookhaven chemist Ping Liu helped to develop models and a theoretical framework to explain why the catalyst works the way it does, using computational resources at Brookhaven’s Center for Functional Nanomaterials (CFN).

    “We modeled different interfaces of gold and molybdenum carbide and studied the reaction mechanism to identify exactly where the reactions take place—the active sites where atoms are binding, and how bonds are breaking and reforming,” she said.

    Additional studies at Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, and two synchrotron research facilities in China added to the scientists’ understanding.

    “This is a multipart complex reaction,” said Liu, but she noted one essential factor: “The interaction between the gold and the carbide substrate is very important. Gold usually bonds things very weakly. With this synthesis method we get stronger adherence of gold to molybdenum carbide in a controlled way.”

    That configuration stabilizes the key intermediate that forms as the reaction proceeds, and the stability of that intermediate determines the rate of hydrogen production, she said.

    The Brookhaven team will continue to study this and other carbide catalysts with new capabilities at the National Synchrotron Light Source II (NSLS-II), a new facility that opened at Brookhaven Lab in 2014, replacing NSLS and producing x-rays that are 10,000 times brighter.

    BNL NSLS-II

    With these brighter x-rays, the scientists hope to capture more details of the chemistry in action, including details of the intermediates that form throughout the reaction process to validate the theoretical predictions made in this study.

    The work at Brookhaven Lab was funded by the U.S. DOE Office of Science.

    Additional funders for the overall research project include: the National Basic Research Program of China, the Chinese Academy of Sciences, National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities of China, and the U.S. National Science Foundation.

    NSLS, NSLS-II, CFN, CNMS, and ALS are all DOE Office of Science User Facilities.

    See the full article here .

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 3:22 pm on June 9, 2017 Permalink | Reply
    Tags: , , BNL NSLS II, Dynamic boundary, Liquid crystal study, , , Phononic or optomechanical applications, , Scattering angle, Tracking dynamic molecular features in soft materials including the high-frequency molecular vibrations that transmit waves of heat sound and other forms of energy, Tuning the structure   

    From BNL: “X-ray Study Reveals Way to Control Molecular Vibrations that Transmit Heat” 

    Brookhaven Lab

    June 6, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    Findings open new pathway for “tuning” materials to ease or insulate against the flow of heat, sound, and other forms of energy.

    1
    Brookhaven Lab members of the research team at the IXS beamline of the National Synchrotron Light Source II, left to right: Dima Bolmatov, Alessandro Cunsolo, Mikhail Zhernenkov, Ronald Pindak (sitting), Alexei Suvorov (sitting), and Yong Cai. The circular track accommodates utility cables and allows the arm housing the detectors to move to different locations to select the scattering angle for the measurement.

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new way to track dynamic molecular features in soft materials, including the high-frequency molecular vibrations that transmit waves of heat, sound, and other forms of energy. Controlling these vibrational waves in soft materials such as polymers or liquid crystal compounds could lead to a range of energy-inspired innovations—from thermal and acoustic insulators, to ways to convert waste heat into electricity, or light into mechanical motion.

    In a paper just published in Nano Letters, the scientists describe using the newly constructed inelastic x-ray scattering (IXS) beamline at the National Synchrotron Light Source II (NSLS-II), which has unprecedented energy resolution, to monitor the propagation of vibrations through a liquid crystal compound in three different phases.


    BNL NSLS-II

    Their findings show that the nanoscale structural changes that occur with increasing temperature—as the liquid crystals become less ordered—dramatically disrupt the flow of vibrational waves. Thus choosing or changing the “phase,” or arrangement of molecules, could control the vibrations and the flow of energy.

    “By tuning the structure, we can change the dynamic properties of this material,” said Brookhaven physicist Dima Bolmatov, the paper’s lead author.

    The technique could also be used to study dynamic processes in other soft systems such as biological membranes or any kind of complex fluid.

    “For example, we could look at how the lipid molecules in a cell membrane cooperate with each other to create tiny porous regions where even smaller molecules, like oxygen or carbon dioxide, can pass through—to see how gas exchange operates in gills and lungs,” Bolmatov said.

    The ability to track such fast dynamic properties would not be possible without the unique capabilities of NSLS-II—a DOE Office of Science User Facility at Brookhaven Lab. NSLS-II produces extremely bright x-rays for studies in a wide range of scientific fields.

    At the IXS beamline, scientists bombard samples with these x-rays and measure the energy they give up or gain with a precision to within two thousandths of an electron volt, as well as the angle at which they scatter off the sample—even at very small angles.

    The energy exchange tells us how much energy it took to make some molecules vibrate in a wave-like motion. The scattering angle probes the vibrations propagating over different length scales inside the sample—from nearly a single molecule to tens of nanometers. The new IXS beamline at NSLS-II can resolve those length scales with unprecedented precision,” said Yong Cai, the lead scientist of the IXS beamline.

    “These two parameters—the scattering angle and the energy—have never before been so well measured in soft materials. So the technical properties of this beamline enable us to precisely locate the vibrations and track their propagation in different directions over different length scales—even in materials that lack a well-ordered solid structure,” he added.

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    The colorful scattering pattern at left reveals molecular level structural information about the layered smectic phase of a liquid crystal material. The inner arcs indicate that the molecules are arrayed in ordered layers with regular spacing, while the outer arcs indicate there is still liquid-like mobility within the layers. The graph (top, right) represents inelastic x-ray scattering measurements from this smectic phase. Each peak (pink, orange, purple) represents a unique vibrational motion moving through the material, where the two “bumps” that make up each peak represent the energy gained or lost by the vibration. The purple and orange vibrations match the frequency of sound waves while the third, pink, vibration is linked to the tilt of the molecules (bottom, right). The out-of-phase rocking back-and-forth of these molecules matches the frequency of infrared light (heat).

    In the liquid crystal study, the Brookhaven Lab scientists and their collaborators at Kent State University and the University at Albany made measurements at three different temperatures as the material went from an ordered, crystalline phase through transitions to a less-ordered “smectic” state, and finally an “isotropic” liquid. They easily detected the propagation of vibrational waves through the most ordered phase, and showed that the emergence of disorder “killed” the propagation of low energy “acoustic shear” vibrations. Acoustic shear vibrations are associated with a compression of the molecules in a direction perpendicular to the direction of propagation.

    “Knowing where the dynamic boundary is—between the material behaving like an ordered solid and a disordered soft material—gives us a way to control the transmission of energy at the nanoscale,” Bolmatov said.

    In the “smectic” phase, the scientists also observed a vibration that was associated instead with molecular tilt. This type of vibration can interact with light and absorb it because the terahertz frequency of the vibrations matches the frequency of infrared light or heat waves. So changing the material properties can control the way these forms of energy move through the material. Those changes can be achieved by changing the temperature of the material, as was done in this experiment, but also by applying external electric or magnetic fields, Bolmatov said.

    This paves the way for new so-called phononic or optomechanical applications, where sound or light is coupled with the mechanical vibrations. Such coupling makes it possible to control a material by applying external light and sound or vice versa.

    “We’re all familiar with applications using the optical properties of liquid crystals in display screens,” Bolmatov said. “We’ve found new properties that can be controlled or manipulated for new kinds of applications.”

    The team will continue studies of soft materials at IXS, including planned experiments with block copolymers, nanoparticle assemblies, lipid membranes, and other liquid crystals over the summer.

    “The IXS beamline is also now opened to external users—including scientists interested in these and other soft materials and biological processes,” said Cai.

    The research team included Dima Bolmatov, Mikhail Zhernenkov, Alexey Suvorov, Ronald Pindak, Yong Cai, and Alessandro Cunsolo of NSLS-II, and Lewis Sharpnack, Deña M. Agra-Kooijman of Kent State University, and Satyendra Kumar of the University at Albany .

    This research was supported by the DOE Office of Science.

    See the full article here .

    Please help promote STEM in your local schools.

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 2:45 pm on February 23, 2017 Permalink | Reply
    Tags: , BNL NSLS II, Instrument finds new earthly purpose, , , , Spectrometry, ,   

    From Symmetry: “Instrument finds new earthly purpose” 

    Symmetry Mag

    Symmetry

    02/23/17
    Amanda Solliday

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

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

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

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

    Keck Array
    Keck Array at the South Pole

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

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

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

    2

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

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

    BNL NSLS-II Interior
    BNL NSLS-II Interior

    ANL APS interior
    ANL APS interior

    SLAC/SSRL
    SLAC/SSRL

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 2:36 pm on December 6, 2016 Permalink | Reply
    Tags: , , , , BNL NSLS II, Don DiMarzio,   

    From BNL: “Q&A with CFN User Don DiMarzio” 

    Brookhaven Lab

    December 6, 2016
    Ariana Tantillo
    atantillo@bnl.gov

    1
    Don DiMarzio. No image credit

    Don DiMarzio is an engineering fellow at Northrop Grumman and a senior scientist within the company’s advanced research, development, design, and demonstration group NG Next, where he studies nanomaterials and radio-frequency metamaterials. He is also an adjunct professor at Stony Brook University, where he teaches a nanotechnology class. Since March 2016, he has been using the advanced characterization labs at the Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven Lab—primarily to investigate nanostructures whose self-assembly is directed through DNA scaffolds. CFN physicist Oleg Gang has been developing this DNA-based technique for several years.

    Northrop Grumman is typically known for building aircraft, such as the U.S. Air Force’s B-2 stealth bomber, as well as unmanned autonomous aircraft and satellites. How does basic research come into play?

    About two years ago, Tom Vice, corporate vice president and president of Northrop Grumman Aerospace Systems, began discussing with his leadership team how to reconstitute the basic research activity that had existed in various forms earlier in the company’s history. NG Next, which includes basic research, applied research and technology development, advanced design, and rapid prototyping, emerged from these discussions. The goal of NG Next is to position Northrop Grumman at the cutting edge of science and technology and to attract the best and brightest young talent.

    NG Next’s basic research group is led by Tom Pieronek, vice president of basic research. The group has eight thrusts or topic areas relevant to the aerospace industry. One of these topics is nanomaterials, which is the focus of the Nanomaterials Group, led by Jesse Tice. I belong to this group. Other thrusts within the basic research group include semiconductor materials, plasmonics, and cognitive autonomy. The charter of our basic research organization is to do real science that is nonproprietary and publishable, in collaboration with the nation’s top universities and government labs. Any fundamental new discoveries that we think are promising may be transferred over to our applied research and prototyping groups within NG Next.

    The Center for Functional Nanomaterials (CFN) is one of five U.S. Department of Energy Nanoscale Science Research Centers and is among the many nanoscale facilities located at universities across the United States. What influenced your decision to submit a user proposal to CFN?

    After I got my PhD in solid-state physics, I did a postdoc at Brookhaven’s National Synchrotron Light Source (NSLS) in the late 1980s and really enjoyed working at Brookhaven.

    BNL NSLS
    BNL NSLS Interior
    BNL/NSLS

    After my postdoc, I became a scientist at the Grumman Corporate Research Center in Bethpage, NY, but continued my collaborations with Brookhaven on and off throughout the years.

    When Northrop Grumman leadership began planning for the new basic research group last year, I got involved. Part of my planning and development work for the group included helping to organize workshops—one in nanomaterials and the other in radio-frequency metamaterials—at our regional headquarters in southern California. For these invite-only workshops, the goal was to learn what was at the cutting edge in research, where we should focus our efforts, and who we could collaborate with.

    Our Nanomaterials Workshop provided a broad perspective on cutting-edge research, from nanomaterials synthesis and structures fabrication through fundamental properties and applications. One area that showed great potential was in nanoparticle self-assembly, and one of the major players in that field is the CFN. Although I had been working with various nanotechnologies before the establishment of NG Next, the CFN was either not established yet or our research was both applied and highly proprietary. But with the establishment of the basic research group within NG Next, it became clear that there was a definite opportunity for collaboration, especially considering that the way CFN is set up aligns with NG Next’s charter to publish, make presentations, and collaborate.

    When I learned about CFN physicist Oleg Gang’s work on exploiting DNA to direct the self-assembly of nanoparticles, I became very intrigued. I was particularly impressed with the strength and flexibility of this DNA origami scaffolding to fabricate a wide range of structures relevant for device and materials applications, and the ability to transition these assemblies from “soft” to “hard” while preserving key functionalities. Northrop Grumman sees this work as a potentially ground-breaking area that may lead to revolutionary new fabrication capability for everything from sensor systems to structural composites.

    While most of NG Next’s basic research group is in California, I am here on Long Island (at our Bethpage facility), so CFN is conveniently located near where I work and live. The group in California is currently building out its own labs that will be separate from our traditional applied laboratories. As an existing facility with state-of-the-art equipment and expertise in nanomaterials synthesis, device fabrication, and advanced characterization, CFN was the perfect complement to our West Coast research operations.

    3
    Gold nanoparticles are coordinated by DNA origami octahedron into the prescribed cluster, as obtained from the 3D transmission electron microscopy reconstruction (based on Y. Tian et al. Nature Nanotechnology 10, 637–644, 2015).

    Are you working on any other projects at CFN besides the directed self-assembly?

    In nanomaterials research, I am supporting principal investigators who are using CFN’s advanced characterization tools, particularly those in microscopy, to look at cutting-edge 2D materials like tin selenide (SnSe) and black phosphorous, in collaboration with our university partners.

    For our nanomaterials work, I am also collaborating with an NG Next group involved in plasmonics research, leveraging our DNA assembly work to fabricate new and unique optical structures.

    What are some of the characterization techniques you use at CFN?

    To probe the composition of the DNA-based nanostructures, we focus on small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). To probe the chemical states of 2D materials and devices, we use energy-dispersive x-ray spectroscopy and electron energy-loss spectroscopy. In addition to these traditional microscopy techniques, we employ aberration-corrected low-energy electron microscopy (LEEM) and angle-resolved photoemission spectroscopy (ARPES) for some of our 2D materials. This latter technique is important because the band structure, or electronic energy levels, of 2D materials often has directional dependence.

    Your work at CFN sounds like it could also benefit from the advanced characterization methods at the National Synchrotron Light Source II (NSLS-II). Are you collaborating with NSLS-II or do you have plans to?

    BNL NSLS II
    BNL NSLS Interior
    BNL/NSLS-II

    Plans are in the works for experiments at the NSLS-II, building on our current efforts at the CFN. We will be working with CFN scientists Dario Stacchiola and Jerzy Sadowski on the new LEEM/ARPES system during its commissioning in January, and we are evaluating the use of synchrotron SAXS for large-volume data acquisition from nanomaterials for additive manufacturing.

    Our leadership is very supportive of our interactions with Brookhaven’s DOE Office of Science User Facilities and would like to solidify relationships for the long term.

    How has it been coming back to Brookhaven more than 30 years later?

    Even though I work for Northrop Grumman, I feel like I am part of the family here at CFN. I am working at CFN pretty much every day. From the start, CFN leadership has been very accommodating. They helped us get rapid access while we started negotiations on our CRADA [cooperative research and development agreement] and submitted our long-range user proposals for the directed assembly and 2D materials projects.

    Since I arrived, CFN staff scientists have been very helpful with training on laboratory equipment such as the SAXS, TEM, and scanning TEM (STEM) systems. The CFN group leads have been particularly helpful in facilitating timely sample preparation, such as that with the focused-ion beam, and with scheduling the use of characterization tools.

    You mentioned you are at CFN basically every day. What keeps you coming back?

    I feel like a kid in a candy shop here. Everyone who works here is passionate about what they do, so coming in every day is something I look forward to. I have my own spare office, close to the group leaders who I am working with. Although I primarily work with Oleg, I get to interact with many other staff scientists and postdocs, not only through my research but also through my volunteer work at CFN. I am the elected vice chair of the CFN Users’ Executive Committee and co-chair of the 2017 NSLS-II & CFN Joint Users’ Meeting.

    How did you become interested in nanomaterials?

    Years ago, I was doing applied research in photocatalysis involving the use of titanium dioxide nanoparticles to create self-decontaminating surfaces—a DARPA [Defense Advanced Research Projects Agency] project. Subsequently, I got involved in developing lightweight carbon nanotube based electrical cables for Department of Defense applications. The carbon nanotube work is ongoing at Northrop Grumman, with applications for space systems and air platforms. Although these applications are important, my turn to basic research was rooted in the NG Next vision to investigate fundamental phenomena that will enable new game-changing technologies that will have applications to both Northrop Grumman’s traditional customers and future technology marketplaces.

    See the full article here .

    Please help promote STEM in your local schools.

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    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.
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  • richardmitnick 10:42 am on October 14, 2016 Permalink | Reply
    Tags: , BNL NSLS II, Cuprates, , , X-ray photon correlation spectroscopy   

    From BNL: “Scientists Find Static “Stripes” of Electrical Charge in Copper-Oxide Superconductor” 

    Brookhaven Lab

    October 14, 2016
    Ariana Tantillo
    atantillo@bnl.gov
    (631) 344-2347
    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Fixed arrangement of charges coexists with material’s ability to conduct electricity without resistance

    1
    Members of the Brookhaven Lab research team—(clockwise from left) Stuart Wilkins, Xiaoqian Chen, Mark Dean, Vivek Thampy, and Andi Barbour—at the National Synchrotron Light Source II’s Coherent Soft X-ray Scattering beamline, where they studied the electronic order of “charge stripes” in a copper-oxide superconductor. No image credit.

    Cuprates, or compounds made of copper and oxygen, can conduct electricity without resistance by being “doped” with other chemical elements and cooled to temperatures below minus 210 degrees Fahrenheit. Despite extensive research on this phenomenon—called high-temperature superconductivity—scientists still aren’t sure how it works. Previous experiments have established that ordered arrangements of electrical charges known as “charge stripes” coexist with superconductivity in many forms of cuprates. However, the exact nature of these stripes—specifically, whether they fluctuate over time—and their relationship to superconductivity—whether they work together with or against the electrons that pair up and flow without energy loss—have remained a mystery.

    Now, scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have demonstrated that static, as opposed to fluctuating, charge stripes coexist with superconductivity in a cuprate when lanthanum and barium are added in certain amounts. Their research, described in a paper published on October 11 in Physical Review Letters, suggests that this static ordering of electrical charges may cooperate rather than compete with superconductivity. If this is the case, then the electrons that periodically bunch together to form the static charge stripes may be separated in space from the free-moving electron pairs required for superconductivity.

    “Understanding the detailed physics of how these compounds work helps us validate or rule out existing theories and should point the way toward a recipe for how to raise the superconducting temperature,” said paper co-author Mark Dean, a physicist in the X-Ray Scattering Group of the Condensed Matter Physics and Materials Science Department at Brookhaven Lab. “Raising this temperature is crucial for the application of superconductivity to lossless power transmission.”

    Charge stripes put to the test of time

    To see whether the charge stripes were static or fluctuating in their compound, the scientists used a technique called x-ray photon correlation spectroscopy. In this technique, a beam of coherent x-rays is fired at a sample, causing the x-ray photons, or light particles, to scatter off the sample’s electrons. These photons fall onto a specialized, high-speed x-ray camera, where they generate electrical signals that are converted to a digital image of the scattering pattern. Based on how the light interacts with the electrons in the sample, the pattern contains grainy dark and bright spots called speckles. By studying this “speckle pattern” over time, scientists can tell if and how the charge stripes change.

    In this study, the source of the x-rays was the Coherent Soft X-ray Scattering (CSX-1) beamline at the National Synchrotron Light Source II (NSLS-II), a DOE Office of Science User Facility at Brookhaven.

    BNL NSLS-II Interior
    BNL NSLS-II

    “It would be very difficult to do this experiment anywhere else in the world,” said co-author Stuart Wilkins, manager of the soft x-ray scattering and spectroscopy program at NSLS-II and lead scientist for the CSX-1 beamline. “Only a small fraction of the total electrons in the cuprate participate in the charge stripe order, so the intensity of the scattered x-rays from this cuprate is extremely small. As a result, we need a very intense, highly coherent x-ray beam to see the speckles. NSLS-II’s unprecedented brightness and coherent photon flux allowed us to achieve this beam. Without it, we wouldn’t be able to discern the very subtle electronic order of the charge stripes.”

    The team’s speckle pattern was consistent throughout a nearly three-hour measurement period, suggesting that the compound has a highly static charge stripe order. Previous studies had only been able to confirm this static order up to a timescale of microseconds, so scientists were unsure if any fluctuations would emerge beyond that point.

    X-ray photon correlation spectroscopy is one of the few techniques that scientists can use to test for these fluctuations on very long timescales. The team of Brookhaven scientists—representing a close collaboration between one of Brookhaven’s core departments and one of its user facilities—is the first to apply the technique to study the charge ordering in this particular cuprate. “Combining our expertise in high-temperature superconductivity and x-ray scattering with the capabilities at NSLS-II is a great way to approach these kind of studies,” said Wilkins.

    To make accurate measurements over such a long time, the team had to ensure the experimental setup was incredibly stable. “Maintaining the same x-ray intensity and sample position with respect to the x-ray beam are crucial, but these parameters become more difficult to control as time goes on and eventually impossible,” said Dean. “When the temperature of the building changes or there are vibrations from cars or other experiments, things can move. NSLS-II has been carefully engineered to counteract these factors, but not indefinitely.”

    “The x-ray beam at CSX-1 is stable within a very small fraction of the 10-micron beam size over our almost three-hour practical limit,” added Xiaoqian Chen, co-first author and a postdoc in the X-Ray Scattering Group at Brookhaven. CSX-1’s performance exceeds that of any other soft x-ray beamline currently operational in the United States.

    In part of the experiment, the scientists heated up the compound to test whether thermal energy might cause the charge stripes to fluctuate. They observed no fluctuations, even up to the temperature at which the compound is known to stop behaving as a superconductor.

    “We were surprised that the charge stripes were so remarkably static over such long timescales and temperature ranges,” said co-first author and postdoc Vivek Thampy of the X-Ray Scattering Group. “We thought we may see some fluctuations near the transition temperature where the charge stripe order disappears, but we didn’t.”

    In a final check, the team theoretically calculated the speckle patterns, which were consistent with their experimental data.

    Going forward, the team plans to use this technique to probe the nature of charges in cuprates with different chemical compositions.

    X-ray scattering measurements were supported by the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by DOE’s Office of Science.

    See the full article here .

    Please help promote STEM in your local schools.

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    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.
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  • richardmitnick 8:06 am on September 18, 2016 Permalink | Reply
    Tags: BNL NSLS II, , ,   

    From Science Alert: “Here’s how physicists accelerate particles to 99.99% the speed of light” 

    ScienceAlert

    Science Alert

    8

    Business Insider

    15 SEP 2016
    ALI SUNDERMIER

    1
    NSLS II. Brookhaven National Laboratory

    By now, you might be familiar with the concept of particle accelerators through the work of the Large Hadron Collider (LHC), the monstrous accelerator that enabled scientists to detect the Higgs boson.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    But the LHC is not alone – the world is equipped with more than 30,000 particle accelerators that are used for a seemingly endless variety of tasks.

    Some of these machines, like the LHC, accelerate particles to nearly the speed of light to smash them together and probe the fundamental building blocks of our universe. Others are used to seal milk cartons and bags of potato chips.

    Brookhaven National Laboratory in New York is home to one of the world’s most advanced particle accelerators: the National Synchrotron Light Source II (NSLS II).

    The NSLS II will allow researchers to do a wide range of science varying from developing better drug treatments, to building more advanced computer chips, to analysing everything from the molecules in your body to the soil you walk on.

    When scientists accelerate particles to these crazy speeds in the NSLS II, they force them to release energy which they can manipulate to do a mind-boggling array of different experiments.

    As electrons moving at nearly the speed of light go around turns, they lose energy in the form of radiation, such as X-rays. The X-rays produced at the NSLS II are extremely bright – a billion times brighter than the X-ray machine at your dentist’s office.

    When scientists focus this extremely bright light onto a very small spot, it allows them to probe matter at an atomic scale. It’s kind of like a microscope on steroids.

    Here’s how the NSLS II pushes particles to 99.99 percent the speed of light – all in the name of science.

    First, the electron gun generates electron beams and feeds them into the linear accelerator, or linac.

    In the linac, electromagnets and microwave radio-frequency fields are used to accelerate the electrons, which must travel in a vacuum to ensure they don’t bump into other particles and slow down.

    Next, the electrons enter a booster ring, where magnets and radio-frequency fields accelerate them to approximately 99.9 percent percent the speed of light.

    Then they are injected into a circular ring called a storage ring.

    3
    Ali Sundermier

    In the storage ring, the electrons are steered by an assortment of magnets.

    The blue magnets bend the motion of the electrons, the yellow magnets focus and defocus the path of the electrons, and the red and orange magnets take outlying electrons and bring them into a closer path.

    The smaller magnets are corrector magnets, which keep the beam in line.

    4
    Ali Sundermier

    This is an insertion device in the storage ring. Insertion devices are magnetic structures that wiggle the electron beam as it passes through the device. This produces an extremely bright and focused beam.

    5
    Ali Sundermier

    As the electrons go around turns in the storage ring, they decelerate slightly, losing energy.

    The lost energy can be converted into different forms of electromagnetic radiation, such as X-rays, that are directed down beamlines running in straight lines tangential to the storage ring.

    At the end of the beamline, the X-rays crash into samples of whatever material is the subject of the experiment.

    6
    Ali Sundermier

    This is an X-ray spectroscopy beamline, where scientists analyse the chemical composition of materials by exciting the electrons in an atom.

    7
    Ali Sundermier

    The circumference of the NSLS-II is so big, nearly half a mile, that many people working there travel around on tricycles.

    The NSLS II is still in the early stages of its development, having just taken over for its successor (the NSLS), in 2014. When it’s complete, it will be able to accommodate about 70 different beamlines.

    8
    Ali Sundermier

    This article was originally published by Business Insider.

    See the full article here .

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  • richardmitnick 8:13 am on September 2, 2016 Permalink | Reply
    Tags: 2016 Microscopy Today Innovation Awards, , , BNL NSLS II, Nathalie Bouet, , X-ray scanning microscope   

    From Brookhaven: Women in STEM – “When Nanofabrication Leads to Nanoscience: Optics Developed at the CFN Bring NSLS-II’s Ultra-Bright x-rays into Focus for Scientific Imaging” Nathalie Bouet 

    Brookhaven Lab

    August 30, 2016
    Ariana Tantillo
    atantillo@bnl.gov

    Optics are critical components in a one-of-a-kind x-ray microscope that was recognized with a 2016 Microscopy Today Innovation Award and named a 2016 R&D 100 Award finalist.

    1
    Nathalie Bouet, who leads Brookhaven’s fabrication of multilayer Laue lenses, uses scanning electron microscopy at the Center for Functional Nanomaterials to image the multilayer after it has been grown. She measures the exact positioning of the layers, making sure these measurements match those expected from her team’s theoretical multilayer design. This quality check is needed before the multilayer can be transformed into usable optics for the microscope.

    At the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, nanofabrication—making structures or devices as small as a few atoms in size—is a daily occurrence at the Center for Functional Nanomaterials, a DOE Office of Science User Facility. Scientists at the National Synchrotron Light Source II (NSLS-II), another DOE Office of Science User Facility at Brookhaven, have been using CFN facilities to develop advanced x-ray focusing optics called multilayer Laue lenses (MLL). These optics have been incorporated into an x-ray scanning microscope installed at the Hard X-ray Nanoprobe (HXN) beamline, where they focus the extremely bright beams of “hard” (high energy) x-rays produced by NSLS-II to nanometer dimensions. Recently, this MLL-based microscope—the only one of its kind—was recognized with one of ten 2016 Microscopy Today Innovation Awards and was named a 2016 finalist for the R&D 100 Awards, which annually celebrate the world’s 100 most innovative technologies.

    “These honors recognize the full extent of the development and construction of the microscope, including all of the research and development work on MLL we’ve done at the CFN,” said NSLS-II physicist Nathalie Bouet, who is leading MLL fabrication at Brookhaven.

    2
    Inside the transmission electron microscopy sample preparation room at the Center for Functional Nanomaterials, Juan Zhou uses a polishing system to prepare a multilayer Laue lens.

    To achieve scientific imaging with extremely high spatial resolution, the optics are integrated onto a custom-built microscope with fine motors that allow extremely accurate positioning, active feedback controls that provide vibrational stability, and components that minimize thermal drifts. With this hardware, the microscope has a resolution equivalent to 50,000 times smaller than a grain of sand. Scientists at NSLS-II use the microscope to collect elemental, structural, and chemical information on everything from soil samples to biological proteins and battery materials.

    Named after physicist Max von Laue, who won the 1914 Nobel Prize in physics for his discovery of x-ray diffraction by crystals, the lenses are made up of several thousand alternating layers of two materials: silicon and tungsten silicide. To grow MLL, the scientists use a deposition system at NSLS-II that individually deposits each layer onto a silicon substrate. Layers are deposited according to a precisely controlled thickness gradient, with the thinnest layers (a few nanometers) laid first and the thickest ones (up to 25 nanometers) last.

    Because even the slightest error in the multilayer stack can have a significant impact on the properties of the optics and thus, the focusing of the x-ray beam, the scientists need to analyze carefully the quality of the stack after it has been grown. Using high-resolution scanning electron microscopy at the CFN, they image the multilayer to measure the exact positioning of the layers. They compare their measurements to those expected from the theoretical multilayer design, applying this information to correct any deviations.

    3
    The multilayer Laue lens module is part of the x-ray microscope (seen above in a vacuum chamber) installed at the National Synchrotron Light Source II’s Hard X-ray Nanoprobe beamline.

    Once the multilayer stack passes the quality test, the next step is to transform it into usable optics for the microscope. To convert the multilayer stack into optics that can be illuminated in transmission, scientists precisely extract very thin sections of the stack—a very challenging endeavor.

    “Sectioning is difficult because the width of the slices is significantly smaller than the thickness of the stacked layers sitting on top of the substrate,” said Brookhaven scientist Juan Zhou, a member of Bouet’s team. As a result, the multilayer sections are very susceptible to bending. If the sections contain any deformations, the lenses cannot effectively focus the x-ray beam. Therefore, very precise sectioning is crucial to ensuring that the lenses can bring x-rays into optimal focus.

    4
    Scientists used mechanical polishing and focused-ion beam milling to fabricate the multilayer Laue lens (MLL) seen in the above scanning electron microscope image. They glued a piece of silicon (Si) on top of the multilayer film to protect it from being damaged during the lens fabrication process.

    5
    This scanning electron microscope image shows the cross-section of a multilayer Laue lens (MLL) with a thickness of 43 micrometers. The cap layer (2 micrometers thick) gives the multilayer additional protection—beyond the protection offered by the glued silicon (Si) layer—against fabrication damages.

    At the CFN, scientists use one of two sectioning techniques, depending on the intrinsic characteristics of the multilayer, the energy of the x-rays that will be used, and the focal length of the lens (the distance between the lens and its focal point, where the x-rays converge). The first technique is based on mechanical polishing, in which both sides of the multilayer are “gritted” down with progressively finer abrasives until the desired thickness and smoothness of the sections are achieved. The second, developed at Brookhaven, is a patented technique based on reactive-ion etching—the removal or “etching” away of a material from its surface through bombardment with a plasma of chemically reactive ions. With both techniques, the scientists often use a focused-ion beam as a final polishing tool.

    Because the lenses are one-dimensional focusing optics, a pair of them is needed to make a focused beam in both directions. As a result, the spacing between the two lenses and the quality of their alignment impact the size of the x-ray beam.

    So far, Bouet’s team has succeeded in focusing x-rays down to 11 nanometers with MLL. But efforts are underway to push the focusing even further and to maximize the number of photons in the focused beam so that HXN users can take full advantage of NSLS-II’s brightness. The team is developing MLL with a “wedged” shape, in which the layers are tilted so that their thickness differs at both ends of the substrate. (The “flat” lenses of the microscope currently in use at the HXN beamline are of equal thickness on both sides of the substrate.) Introducing a gradient inside the multilayer means each layer forms a slightly different angle than the one before it. This geometry allows MLL to diffract x-rays more efficiently; early tests have demonstrated that the wedged lenses make use of 27 percent of the x-ray beam, twice the amount used by a flat MLL.

    The other members of the microscope development team are Brookhaven physicists Yong Chu (HXN beamline group leader), Xiaojing Huang, Evgeny Nazaretski, and Hanfei Yan, design engineer Brian Mullany, technical specialist Dennis Kuhne, software analyst Kenneth Lauer, as well as DOE Argonne National Lab engineer Deming Shu.

    See the full article here .

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    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.
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  • richardmitnick 10:09 am on May 6, 2016 Permalink | Reply
    Tags: , BNL NSLS II, Supercooled Cavities for Particle Acceleration,   

    From BNL: “Supercooled Cavities for Particle Acceleration” 

    Brookhaven Lab

    May 3, 2016
    Ariana Tantillo

    Very low temperatures support research at Brookhaven National Laboratory’s National Synchrotron Light Source II

    BNL NSLS-II Building
    BNL NSLS-II Building

    BNL NSLS-II Interior
    BNL NSLS-II Interior

    1
    A superconducting radio-frequency cryomodule installed in the NSLS-II ring. No image credit.

    When you think about the coldest places on Earth, the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility located at the DOE’s Brookhaven National Laboratory, probably doesn’t come to mind. But accelerating electrons around the half-mile-long ring of NSLS-II at nearly the speed of light requires some extremely cold temperatures, hundreds of degrees below the freezing point of water.

    Supercool temperatures mean super cool science research can go on.

    A continuous flow of electrons

    As electrons circle around NSLS-II’s ring, they emit extremely bright X-rays that scientists use to image materials, such as soil samples, batteries, and biological proteins. “The images are not necessarily photographs, but spectrum, absorption lines, or diffraction patterns,” explained James Rose, head of the Radio Frequency Systems Group for NSLS-II.

    By studying the fluorescence, diffraction, scattering, and absorption of X-rays, scientists can uncover a material’s atomic structure, which gives rise to its chemical, electronic, and structural properties. From examining soil samples to understand the uptake of chemical runoff, to watching in real time as batteries operate to discover where and how materials inside break down, to examining the structure of biological proteins to help design new drugs for treating disease, scientists at NSLS-II probe the inner workings of various kinds of materials.

    In producing these X-rays, the electrons lose energy and slow down. For the electrons to continue generating the high-power X-ray beams used by scientists from around the world to image materials, this energy must be replenished.

    At NSLS-II, electrons gain this energy by passing through two hollow metal (niobium) chambers called radio-frequency (RF) cavities that contain an electromagnetic field. The electric field transfers energy to the electrons, propagating them along the ring. “An RF cavity is a resonator like an organ pipe or guitar string,” said Rose. “Our cavities are tuned to a particular frequency such that an electron traveling around the ring passes through the cavity at the same phase each trip, and gains the same energy per pass as it loses energy to synchrotron radiation, or light. Giving energy to the electron at just the right time increases its energy, much like someone pushing a child on a swing.”

    When cooled to an extremely low, or cryogenic, temperature, the niobium in the RF cavity becomes superconducting—that is, it loses nearly all resistance to an electric current. As a result, electrons can flow freely through the cavities. If niobium were conducting electricity as it would at room temperature, there would be a large resistance to the flow of electrons. When electron flow is resisted, the electrical energy that moves the electrons is converted into heat energy—a waste product. Without this resistance, electricity can be delivered to the cavity much more efficiently.

    “If the cavities were not superconducting, almost seven times more energy would be required to keep the electrons flowing to produce high-intensity X-ray beams,” said Rose.

    The superconductivity not only reduces energy loss in the cavities but it also provides for electron beam stability.

    “Because we don’t need to worry about keeping resistive losses low, we can design the cavities with a large aperture that allows resonant frequencies above the cavity’s tuned frequency to leak out of the cavity into absorbers that damp, or reduce the amplitude of, the higher-frequency oscillations. If these higher frequencies were not damped, they would add and subtract energy from the beam out of sequence. That’s like pushing the child on the swing randomly, causing the swing to slow down or stopping the child short at the highest speed,” explained Rose.

    Supercooled cavities

    At NSLS-II, the RF cavities are continuously immersed in liquid helium, which, with the help of liquid nitrogen, cools niobium to its superconducting state. The cavities are installed within cryomodules, which are essentially vacuum-insulated containers like thermos bottles that maintain the ultra-cold temperatures of the liquid helium to allow for near-zero electrical resistance within the RF cavity.

    2
    Brookhaven Lab staff members (left to right) James Rose, John Gosman, and William Gash with one of the two electron bunch–lengthening radio-frequency cavities that will be installed at the National Synchrotron Light Source II (NSLS-II). By reducing the number and intensity of collisions between electrons circling the NSLS-II electron storage ring, these cavities will help prevent electron beam loss and thus extend the lifetime of the beams used to conduct experiments.

    “The only way to make liquid helium from gaseous helium is to cool it down,” explained Rose. “Because nitrogen is inexpensive as compared to helium, we use liquid nitrogen to precool the helium from room temperature down to liquid nitrogen’s boiling point of 321 degrees below zero. From there, we cool the helium down to approximately minus 450 degrees Fahrenheit.”

    Cooling helium gas into a liquid is a multistep process. First, the gas is squeezed in compressors. As the gas molecules are forced into a smaller volume, the pressure and temperature of the gas rise. The gas is then fed into an insulated enclosure called a cold box, where three fast-moving expansion turbines liquefy the gas by reducing its pressure, causing the gas molecules to spread apart. This rapid expansion causes the gas to cool and a portion of it to liquefy.

    “The cold box is the heart of the cryogenic plant,” said William Gash, a cryogenics engineer in Brookhaven’s Utilities Group. “Its turbines rotate at many thousands of revolutions per second, as compared to a car, which operates in revolutions per minute.”

    Once liquefied, the helium is stored in a large vacuum-insulated container and distributed through insulated piping and control valves directly into the cryomodules to surround the RF cavities.

    The remaining cooled gas is returned to the cold box, where it flows through heat exchangers to precool the incoming high-pressure gas before being sent to the compressor to start the cycle again.

    “The cryogenics plant is a closed-loop system,” explained Gash. “All of the helium is recovered. Even in the event of an emergency, we have a recovery system in place to ensure the supply is retrieved.”

    Longer-lived beams

    In the next five years or so, additional superconducting RF cavities and valves will be installed.

    “This installation will provide the RF power needed to support more beams and thus more experiments at NSLS-II,” said Rose.

    Two of the cavities will be electron bunch–lengthening cavities, which “lengthen” the bunches, or groups, of electrons traveling around the ring.

    In dense bunches, electrons circling the ring undergo collisions with other electrons in the bunch. “Imagine dancers that bump into one another on a crowded dance floor,” said Rose.

    These collisions scatter the electrons, causing some electrons to be ejected from the bunch. Eventually, these ejected electrons hit the beam pipe and lose their energy to radiation. “Some dancers leave the dance floor and go home,” said Rose. “By lengthening the electron bunches (increasing the size of the dance floor), we can reduce the density of electrons (spreading people out on the dance floor), thereby reducing the number and intensity of the collisions. Ultimately, these new cavities will extend the lifetime of the beams.”

    See the full article here .

    Please help promote STEM in your local schools.

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    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.
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