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  • richardmitnick 9:54 am on December 6, 2019 Permalink | Reply
    Tags: , BNL, , , NSLS,   

    From D.O.E. Office of Science via Brookhaven National Lab: “The Big Questions: José Rodriguez on Catalysts” 

    Brookhaven National Lab

    December 4, 2019
    José Rodriguez

    1
    Distinguished Scientists Fellow José Rodriguez from Brookhaven Lab worked with fellow chemist Ping Liu to characterize structural and mechanistic details of a low-temperature catalyst for producing hydrogen gas from water and carbon monoxide.
    Image courtesy of Brookhaven National Laboratory.

    The Big Questions series features perspectives from the five recipients of the Department of Energy Office of Science’s 2019 Distinguished Scientists Fellows Award describing their research and what they plan to do with the award.

    Contributing Author Credit: José Rodriguez is a senior chemist at Brookhaven National Laboratory.

    How can we use some of the world’s brightest and strongest sources of synchrotron light to better understand the catalysts that speed up chemical reactions?

    Catalysts reduce the energy needed to make a chemical reaction take place. They’re essential in industry, used for making everything from fabric to synthetic plants. Catalysts are used in the production of many chemicals and fuels.

    Over the years, people have tried to understand how catalysts work in hopes of making them even better. To understand how a catalyst works, you need to see what happens at its active sites during chemical transformations. This is a very complex thing. You need a lot of tools to see how the catalyst changes over time, especially under harsh environmental conditions like high pressures and temperatures. Synchrotrons – incredibly powerful sources of light that produce X-rays – can provide a unique look into how these catalysts work.

    When I first arrived at the Department of Energy’s Brookhaven National Laboratory (BNL) 29 years ago, scientists were for the first time seriously proposing the use of a synchrotron to study catalysts. At that time, there was a lot of activity in the National Synchrotron Light Source (NSLS), a DOE Office of Science user facility.

    BNL NSLS

    At the end of my job interview, the head of BNL’s Chemistry Department asked, “How much money do you need to do this kind of science?” I said, “This is a very complex science. I need $750,000.” As a physical inorganic chemist, $50,000 was a lot of research money for him. But despite the price tag, he looked at me and said, “Okay, we’ll see what we can do.” He called up the person at DOE in charge of the catalysis program and said, “The young man looks very promising; we want to go into this new area. He needs $750,000.”

    With that funding, my team and I used NSLS to study catalysts in very controlled environments. We created these environments by putting the catalysts in specialized ultra-high vacuum chambers originally developed by NASA in the 1960s. After setting the inside of the chambers to the conditions we wanted, we put them in the synchrotron. The hard and soft X-rays from the synchrotron made it possible to study the structural, electronic, and chemical properties of the catalytic material as well as how those changed during the reaction process.

    There is still a big interest in the DOE Office of Science in understanding these catalytic materials. Since then, the NSLS has been replaced by its successor NSLS-II [below], which is also a DOE Office of Science user facility. With NSLS-II, we can use a high-intensity beam to do ultra-fast measurements. Now, we can make in-situ measurements of samples with highly diluted elements in times as short as milliseconds (a thousandth of a second). With this speed, we can now monitor catalysts’ properties during reactions very quickly. In catalysis research, the faster you can go, the better.

    With this fellowship, I’m going to expand the work we’re doing at the NSLS-II to better understand catalysts’ properties and how they change during reactions. While we’ve been working on this project for about five years, this new funding will help us move it forward. This work will involve not just the NSLS-II, but also researchers at BNL’s Center for Functional Nanomaterials (a DOE Office of Science user facility), the University of Kansas, Stony Brook University, and Columbia University. In the spirit of this fellowship, any equipment we develop will remain at the NSLS-II, where it will be available for the entire catalysis community to use.

    I think this project has the potential to make a big contribution to the field and I appreciate the opportunity the DOE’s Office of Science has provided me to lead it.

    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.
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  • richardmitnick 9:33 am on December 6, 2019 Permalink | Reply
    Tags: 3-D printed metals, , Alessandra Colli, , BNL, , Plasma 3-D printing,   

    From Brookhaven National Lab: Women in STEM- “Meet Alessandra Colli: Engineering Improvements in 3-D-printed Metals” 

    From Brookhaven National Lab

    December 3, 2019
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    Colli seeks to merge materials risk analysis with data collected at world-class science tools to improve safety, reliability, and opportunities in metal additive manufacturing.

    1
    Alessandra Colli with National Synchrotron Light Source II beamline scientist Larry Carr at a beamline used for far-infrared spectroscopy (MET). This beamline will help characterize filter samples made by Obsidian AM, a company partnering with Brookhaven Lab to explore 3-D printing as a strategy for producing high-precision radiation filters for next-generation cosmic microwave background studies.

    With a background in electrical engineering and risk assessment, Alessandra Colli, a scientist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, wants airplane engines to function flawlessly, rockets to be reliable, and a new telescope to be sensitive to signals that could solve secrets of the universe. Her focus, however, is not on the electronic circuitry that powers these complex devices, but rather on improving the structure and function of their many metallic components.

    Colli is developing a strategy to leverage Brookhaven Lab’s materials-science capabilities and data analytics approaches to advance metal “additive manufacturing,” also known as 3-D printing. Compared with conventional metal manufacturing, 3-D printing offers great promise for building metal components with higher precision and greater reliability from the bottom up.

    “When you are talking about reliability, most of the time you look at the system level—how the part performs in the field, in the real-world application,” Colli said. “We want to bring in the basic materials science—the kinds of studies we can do at the National Synchrotron Light Source II (NSLS-II) and the Center for Functional Nanomaterials (CFN) to look at material properties and defects at very small scales—along with analytical techniques being developed by our Computational Science Initiative to efficiently sift through that data.”

    This approach could help scientists identify sources of material imperfections or weakness—and explore how different 3-D printing approaches or even new materials could improve a particular product.

    “Industrial partners could come in and we can help them solve specific issues using the enormous capabilities of our DOE Office of Science user facilities,” Colli said.

    3-D printed metals

    Once used mainly for creating prototypes or models, additive manufacturing is moving into the mainstream for a range of industrial and defense applications, so much so that many industrial players address it as the next industrial revolution in manufacturing, Colli said. Using 3-D printing to manufacture precision metal engine components, high-tech filters, or even construction hinges and brackets offers ways to reduce waste of feedstock material and dramatically improve design to achieve better performance of the final product, she noted.

    Instead of whittling down a larger block of metal, pouring molten material into a mold, or making separate components that must later be fastened together, 3-D printing uses a range of techniques to deposit the material layer by layer, printing only the desired object with little material wasted. The technology can create intricate objects and even allows construction from composite materials.

    But to ensure durability, strength, resistance to corrosion, or other characteristics important for specific applications, it’s essential to understand not just what the manufactured part looks like and how it works in its application, but also what’s going on inside—the characteristics of the material itself.

    Think about a piece that might be part of an airplane, or supporting parts for construction, part of a rocket engine or ship—these parts need extremely high reliability.

    “With additive manufacturing, there can be different types of defects—residual stress that creates tension in an area where you may not want it; porosity formed by bubbles that create a weak spot where the part can break. We have a range of techniques that can see these structural characteristics and the materials’ chemical composition. And we can study them under different environmental conditions, like pressure or high heat, that when combined with certain material characteristics can cause a failure,” Colli said.

    These tools can also help identify the best additive manufacturing processes for different applications, fine-tune manufacturing precision to take into account post-processing steps such as polishing or annealing, or explore new materials or combinations of materials that may improve functions.

    Building collaborations

    “There are lots of opportunities to grow collaborations with academic partners, industry, other departments at Brookhaven, and the user facilities here and at the other DOE Labs or research institutions around the world,” Colli said.

    As an example, Colli notes one collaboration already underway among scientists in Brookhaven’s Sustainable Energy Technologies Department, Physics Department, Instrumentation Division, NSLS-II, and Obsidian AM (a small spin-off company from Yale University in Connecticut) that hopes to develop filters for cosmic microwave background radiation [CMB].

    CMB per ESA/Planck

    These filters, designed for use in next-generation telescopes, are typically fabricated from metal as meshes or grids that get laminated together. Their job is to screen out signals from other forms of radiation so scientists can collect echoes of the radiation leftover from the Big Bang. Filtering out the “noise” will help physicists decipher details about neutrinos, dark matter, and general relativity.

    3
    Scientific exploration of new materials, composites, and 3-D printing processes along with engineering studies of new applications will open many opportunities in metal additive manufacturing. This approach could guide the development of 3-D printed materials with reliability in harsh environments, reduced size and weight, or other characteristics optimized for specific applications.

    “We are exploring plasma 3-D printing as a way to directly manufacture the full metamaterial for these filters. We’re starting by making sure we can print the metal part with optimal precision, but we are hoping to be able to print alternate layers of insulating material and metal grid directly using the same 3-D printing process,” Colli said.

    This approach could be applied to making other layered metamaterials and composites, such as high-temperature superconductors (promising materials that carry electric current with no resistance) and magnets.

    Colli is finalizing plans with professors at the North Carolina A&T State University and Rensselaer Polytechnic Institute to bring students in to learn about the various 3-D printing technologies, materials characterization tools such as x-ray diffraction, and approaches such as tensile stress testing. She is also collaborating with computational scientists to develop the tools and algorithms—many based on machine learning and other forms of “artificial intelligence”—to identify key indicators that will predict (and guide design to avoid) failure in additively manufactured metal components.

    Varied background, open mind

    “I’m not a materials scientist and I’m not a physicist, so to build this strategy and these collaborations, I had to learn everything too, including about the techniques; and I’m still learning,” Colli said. “My strength is to be able to understand both the small details and the big picture.”

    Colli attributes her wide-scale vision to the diversity of topics she studied early in her career: electrical power engineering for her master thesis and risk analysis for her Ph.D., the former at the Polytechnic University of Milan in Italy and the latter at Delft University of Technology in The Netherlands. “Diversifying things gives perspective in terms of what you can learn and what you can see. It really opens up your mind,” she said.

    She spent six years in The Netherlands developing methods to compare technological, environmental, and occupational risks of various energy technologies—fossil fuels, nuclear, and renewable energies such as solar. When she first came to Brookhaven Lab in 2011, she worked to integrate risk analysis into the economic side of evaluating energy systems.

    4
    Simulations of filters for cosmic microwave background radiation telescopes help identify the best configuration for optimal performance. This graphic shows one layer of the copper configuration simulated using CST Studio Suite, a 3-D electromagnetic analysis software program. The simulation determines what types of radiation get transmitted through or filtered out by the mesh.

    The proximity of the Northeast Solar Energy Research Center to NSLS-II first sparked her idea that understanding material properties might help address an energy challenge: why photovoltaic solar cells sometimes crack.

    “My idea was to apply my knowledge in risk analysis to reliability issues in photovoltaics. What is the impact of the different materials that make up these layered structures on the tendency of cracks to form and propagate, for example? We have the solar panels and the synchrotron right here to do the materials science testing,” she said.

    In 2018, Jim Misewich, Associate Laboratory Director for Energy and Photon Sciences (EPS), asked her to develop the Lab’s strategy for metal additive manufacturing as part of the EPS Growth plan. This opportunity gave her a chance to bring her idea of correlating material properties with performance and reliability to a new challenge.

    “I had to grow in my career, to go from being a scientist doing my job in the lab to develop a leadership mentality,” she said. With support from the Growth Office—including Elspeth McSweeney, Michael Cowell, and Jun Wang—she developed skills and sought professional training courses such as the Women in STEM Leadership program at Stony Brook University.

    “It was a year of enormous growth,” she said. “When people believe in you and they give you a chance, you feel obligated to give something back and to be successful. Supporting other people at the Lab helps us push each other.”

    Meaningful mentorship

    Colli puts these philosophies into practice as she mentors students through Brookhaven Lab’s Office of Educational Programs.

    “For me, research is always about teamwork. I am not the boss and you are not my slave; we work together, period. It’s a continuous exchange,” she said. “I let the students bring up ideas—have them tell me what we should do.”

    Sometimes suspicious of this approach and a bit lost without a predetermined path, Colli’s students often end up with an appreciation of what it means to be part of the scientific process.

    “I don’t care if they do perfect work or not. But when I see that they get engaged and they get passionate, that’s for me the best reward.”

    From her own experience, she also tells them, “Don’t be afraid if you end up in a different field because that may only increase your knowledge and open up your mind in different directions.”

    When she’s not developing new strategies at the Lab, Colli loves to connect with nature by hiking and especially riding her horse. “That is where I find my peace of mind,” she said.

    “I really love to be on Long Island, and I love the U.S.,” she added, noting that she hopes to become a full U.S. citizen as soon as she is eligible. “I still have two years to wait for that and I’m counting the days.”

    The metal additive manufacturing strategy is supported by Brookhaven Lab’s program development funds. NSLS-II and CFN are DOE Office of Science user facilities. The Computational Science Initiative is also supported 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.
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  • richardmitnick 9:45 am on November 22, 2019 Permalink | Reply
    Tags: , BNL, , ,   

    From Brookhaven National Lab: “Turning Up the Heat to Create New Nanostructured Metals” 

    From Brookhaven National Lab

    November 20, 2019
    Ariana Manglaviti
    amanglaviti@bnl.gov
    (631) 344-2347

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

    Scientists used heat to drive a spontaneous process in which different metals mixed to form 3-D interlocking nanostructures in thin films, with applications for catalysts, solar cells, and biomedical sensors.

    1
    Kim Kisslinger, Karen Chen-Wiegart, Bruce Ravel, Xiaojing Huang, Fernando Camino, Yong Chu, Hanfei Yan, Ming Lu, Chonghang Zhao, Cheng-Hung Lin, Mingzhao Liu, and Evgeny Nazaretski outside Brookhaven Lab’s Center for Functional Nanomaterials (CFN). The scientists used the Nanofabrication and Electron Microscopy facilities at the CFN and the Hard X-ray Nanoprobe and Beamline for Materials Measurement at the National Synchrotron Light Source II (pictured in the background) to synthesize and characterize metallic thin films with a bicontinuous structure formed via dealloying.

    Scientists have developed a new approach for making metal-metal composites and porous metals with a 3-D interconnected “bicontinuous” structure in thin films at size scales ranging from tens of nanometers to microns. Metallic materials with this sponge-like morphology—characterized by two coexisting phases that form interpenetrating networks continuing over space—could be useful in catalysis, energy generation and storage, and biomedical sensing. Called thin-film solid-state interfacial dealloying (SSID), the approach uses heat to drive a self-organizing process in which metals mix or de-mix to form a new structure. The scientists used multiple electron- and x-ray-based techniques (“multimodal analysis”) to visualize and characterize the formation of the bicontinuous structure.

    “Heating gives the metals some energy so that they can interdiffuse and form a self-supported thermodynamically stable structure,” explained Karen Chen-Wiegart, an assistant professor in Stony Brook University’s (SBU) Materials Science and Chemical Engineering Department, where she leads the Chen-Wiegart Research Group, and a scientist at the National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory. “SSID has been previously demonstrated in bulk samples (tens of microns and thicker) but results in a size gradient, with a larger structure on one side of the sample and a smaller structure on the other side. Here, for the first time, we successfully demonstrated SSID in a fully integrated thin-film processing, resulting in a homogenous size distribution across the sample. This homogeneity is needed to create functional nanostructures.”

    Chen-Wiegart is the corresponding author on a paper published online in Materials Horizons that is featured on the Nov. 18 online journal issue cover. The other collaborating institutions are the Center for Functional Nanomaterials (CFN)—another DOE Office of Science User Facility at Brookhaven Lab—and the National Institute of Standards and Technology (NIST).

    To demonstrate their process, the scientists prepared magnesium (Mg) and iron (Fe) and nickel (Ni) alloy thin films on silicon (Si) wafer substrates in the CFN Nanofabrication Facility. They heated the samples to high temperature (860 degrees Fahrenheit) for 30 minutes and then rapidly cooled them down to room temperature.

    “We found that Mg diffuses into the Fe-Ni layer, where it combines only with Ni, while Fe separates from Ni,” said first author Chonghang Zhao, a PhD student in the Chen-Wiegart Research Group. “This phase separation is based on enthalpy, an energy measurement that determines whether the materials are “happily” mixing or not, depending on properties such as their crystal structure and bonding configurations. The nanocomposite can be further treated to generate a nanoporous structure through chemically removing one of the phases.”

    2
    A schematic showing thin-film SSID for the Fe-Ni/Mg system. The thin films of Mg and Fe-Ni are layered on top of an Si substrate. Upon exposure to heat, the Mg dealloys Fe-Ni to form an Mg-Ni composite and pure Fe with a 3-D bicontinuous structure.

    Nanoporous structures have many applications, including photocatalysis. For example, these structures could be used to accelerate the reaction in which water is split into oxygen and hydrogen—a clean-burning fuel. Because catalytic reactions happen on material surfaces, the high surface area of the pores would improve reaction efficiency. In addition, because the nanosized “ligaments” are inherently interconnected, they do not need any support to hold them together. These connections could provide electrically conductive pathways.

    The team identified the dealloyed bicontinuous structure of Fe and Ni-Mg through complementary electron microscopy techniques at the CFN and x-ray synchrotron techniques at two NSLS-II beamlines: the Hard X-ray Nanoprobe (HXN) and Beamline for Materials Measurement (BMM).

    “Using the scanning mode in a transmission electron microscope (TEM), we rastered the electron beam over the sample in specific locations to generate 2-D elemental maps showing the spatial distribution of elements,” explained Kim Kisslinger, a technical associate in the CFN Electron Microscopy research group and the point of contact for the instrument.

    3
    The scientists used a scanning transmission electron microscope (STEM) to study the structure and composition of Fe-Ni films dealloyed by an Mg film. In particular, they combined high-angle annular dark-field (HAADF) imaging with energy-dispersive x-ray spectroscopy (EDS). HAADF imaging is sensitive to the atomic number of elements in the sample. Elements with a higher atomic number scatter more electrons, causing them to appear brighter in the resulting greyscale image. For the EDS maps, the different colors correspond to individual elements and the color intensity to their local relative concentration. STEM analysis revealed the formation of two phases: pure Fe (magenta) and an Ni-Mg (yellow-purple) composite.

    The team also used TEM to obtain electron diffraction patterns capturing the crystal structure and a scanning electron microscope (SEM) to study surface morphology.

    This initial analysis provided evidence of the formation of a bicontinuous structure locally in 2-D at high resolution. To further confirm that the bicontinuous structure was representative of the entire sample, the team turned to HXN beamline, which can provide 3-D information over a much larger region.

    “With HXN, we can focus hard, or high-energy, x-rays to a very tiny spot of about 12 nanometers,” said coauthor and HXN physicist Xiaojing Huang. “The world-leading spatial resolution of hard x-ray microscopy at HXN is sufficient to see the sample’s smallest structures, which range in size from 20 to 30 nanometers. Though TEM provides higher resolution, the field of view is limited. With the x-ray microscope, we were able to observe the 3-D element distributions within a bigger area so that we could confirm the homogeneity.”

    Measurements at HXN were conducted in a multimodality manner, with the simultaneous collection of x-ray scattering signals that reveal 3-D structure and fluorescence signals that are element-sensitive. Atoms emit fluorescence when they jump back to their lowest-energy (ground) state after being excited to an unstable higher-energy state in response to the x-ray energy. By detecting this characteristic fluorescence, scientists can determine the type and relative abundance of elements present at specific locations.


    A video based on the 3-D x-ray fluorescence nanotomography of the Fe-Ni thin film conducted at the Hard X-ray Nanoprobe.

    Coauthor and NIST Synchrotron Science Group physicist Bruce Ravel confirmed the sample’s chemical composition and obtained the precise chemical forms (oxidation states) of the elements at BMM, which is funded and operated by NIST. The x-ray absorption near-edge structure (XANES) spectra also showed the presence of pure Fe.

    Now that the scientists have shown that SSID works in thin films, their next step is to address the “parasitic” events they identified in the course of this study. For example, they discovered that Ni diffuses into the Si substrate, leading to voids, a kind of structural defect. They will also make pore structures from the metal-metal composites to demonstrate applications such as photocatalysis, and apply their approach to other metal systems, including titanium-based ones.

    This work was in part supported by a student fellowship by the Brookhaven-SBU Joint Photon Sciences Institute and the National Science Foundation’s Faculty Early Career Development Program and Metals and Metallic Nanostructures 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.
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  • richardmitnick 4:01 pm on November 8, 2019 Permalink | Reply
    Tags: "The Secret Behind Crystals that Shrink when Heated", A group from Caltech was using one method to explore this mystery at the Spallation Neutron Source At Oak Ridge National Laboratory., A long-standing materials science mystery: why certain crystalline materials shrink when heated., , BNL, , The BNL scientists paired up with the Caltech team to collect data at SNS using Caltech’s ScF3 samples to track how the distances between neighboring atoms changed with increasing temperature.   

    From Brookhaven National Lab: “The Secret Behind Crystals that Shrink when Heated” 

    From Brookhaven National Lab

    November 1, 2019

    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    Discovery yields new quantitative description of unusual behavior relevant to materials used in electronics, medicine, telecommunications, and more.

    1
    Igor Zaliznyak, a physicist in Brookhaven Lab’s Condensed Matter Physics and Materials Science Division (right), led a team of scientists including Alexei Tkachenko of the Lab’s Center for Functional Nanomaterials (left) to decipher the mechanism underlying scandium fluoride’s ability to shrink upon heating.

    Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have new experimental evidence and a predictive theory that solves a long-standing materials science mystery: why certain crystalline materials shrink when heated. Their work, just published in Science Advances, could have widespread application for matching material properties to specific applications in medicine, electronics, and other fields, and may even provide fresh insight into unconventional superconductors (materials that carry electric current with no energy loss).

    The evidence comes from precision measurements of the distances between atoms in crystals of scandium fluoride (ScF3), a material known for its unusual contraction under elevated temperatures (also known as “negative thermal expansion”). What the scientists discovered is a new type of vibrational motion that causes the sides of these cube-shaped, seemingly solid crystals to buckle when heated, thus pulling the corners closer together.

    “Normally as something heats up, it expands,” said Brookhaven physicist Igor Zaliznyak, who led the project. “When you heat something up, atomic vibrations increase in magnitude, and the overall material size increases to accommodate the larger vibrations.”

    That relationship, however, doesn’t hold for certain flexible materials, including chainlike polymers such as plastics and rubber. In those materials, increasing heat increases vibrations only perpendicular to the length of the chains (picture the sideways vibrations of a plucked guitar string). Those transverse vibrations pull the ends of the chains closer together, resulting in overall shrinkage.

    But what about scandium fluoride? With a solid, cubic crystalline structure, it looks nothing like a polymer—at least at first glance. In addition, a widespread assumption that the atoms in a solid crystal have to maintain their relative orientations, no matter what the crystal size, left physicists confounded to explain how this material shrinks when heated.

    2
    This animation shows how solid crystals of scandium fluoride shrink upon heating. While the bonds between scandium (green) and fluorine atoms (blue) remain relatively rigid, the fluorine atoms along the sides of the cubic crystals oscillate independently, resulting in a wide range of distances between neighboring fluorine atoms. The higher the temperature, the greater the buckling in the sides of the crystals leading to the overall contraction (negative thermal expansion) effect.

    Neutrons and a dedicated student to the rescue

    A group from the California Institute of Technology (Caltech) was using one method to explore this mystery at the Spallation Neutron Source (SNS), a DOE Office of Science user facility at Oak Ridge National Laboratory. Measuring how beams of neutrons, a type of subatomic particle, scatter off the atoms in a crystal can give valuable information about their atomic-scale arrangement. It’s particularly useful for lightweight materials like fluorine that are invisible to x-rays, Zaliznyak said.

    3
    Scientists used neutron scattering at the Spallation Neutron Source at Oak Ridge National Laboratory to investigate why certain crystalline materials shrink when heated. Credit: Oak Ridge National Laboratory

    Hearing about this work, Zaliznyak noted that his colleague, Emil Bozin, an expert in a different neutron-scattering analysis technique, could probably advance understanding of the problem. Bozin’s method, known as “pair distribution function,” describes the probability of finding two atoms separated by a certain distance in a material. Computational algorithms then sort through the probabilities to find the structural model that best fits the data.

    Zaliznyak and Bozin paired up with the Caltech team to collect data at SNS using Caltech’s ScF3 samples to track how the distances between neighboring atoms changed with increasing temperature.

    David Wendt, a student who began a Brookhaven Lab High School Research Program internship in Zaliznyak’s lab following his sophomore year in high school (now a freshman at Stanford University), handled much of the data analysis. He continued working on the project throughout his high-school days, earning the position of first author on the paper.

    “David basically reduced the data to the form that we could analyze using our algorithms, fitted the data, composed a model to model the positions of the fluorine atoms, and did the statistical analysis to compare our experimental results to the model. The amount of work he did is like what a good postdoc would do!” Zaliznyak said.

    “I am very grateful for the opportunity Brookhaven Lab provided me to contribute to original research through their High School Research Program,” Wendt said.

    Results: “soft” motion in a solid

    The measurements showed that the bonds between scandium and fluorine don’t really change with heating. “In fact, they expand slightly,” Zaliznyak said, “which is consistent with why most solids expand.”

    But the distances between adjacent fluorine atoms became highly variable with increasing temperature.

    “We were looking for evidence that the fluorine atoms were staying in a fixed configuration, as had always been assumed, and we found quite the opposite!” Zaliznyak said.

    4
    Additional coauthors on the study included (from left) Kate Page, formerly of Oak Ridge National Laboratory, Brookhaven Lab physicist Emil Bozin, and ORNL instrument scientist Joerg Neuefeind. Credit: Genevieve Martin/Oak Ridge National Laboratory

    Alexei Tkachenko, an expert in the theory of soft condensed matter at Brookhaven Lab’s Center for Functional Nanomaterials (another Office of Science user facility) made essential contributions to the explanation for this unexpected data.

    Since the fluorine atoms appeared not to be confined to rigid positions, the explanation could draw on a much older theory originally developed by Albert Einstein to explain atomic motions by considering each individual atom separately. And surprisingly, the final explanation shows that heat-induced shrinkage in ScF3 bears a remarkable resemblance to the behavior of soft-matter polymers.

    “Since every scandium atom has a rigid bond with fluorine, the ‘chains’ of scandium-fluoride that form the sides of the crystalline cubes (with scandium at the corners) act similar to the rigid parts of a polymer,” Zaliznyak explained. The fluorine atoms at the center of each side of the cube, however, are unrestrained by any other bonds. So, as temperature increases, the “underconstrained” fluorine atoms are free to oscillate independently in directions perpendicular to the rigid Sc-F bonds. Those transverse thermal oscillations pull the Sc atoms at the corners of the cubic lattice closer together, resulting in shrinkage similar to that observed in polymers.

    Thermal matching for applications

    This new understanding will improve scientists’ ability to predict or strategically design a material’s thermal response for applications where temperature changes are expected. For example, materials used in precision machining should ideally show little change in response to heating and cooling to maintain the same precision across all conditions. Materials used in medical applications, such as dental fillings or bone replacements, should have thermal expansion properties that closely match those of the biological structures in which they are embedded (think how painful it would be if your filling expanded while your tooth contracted when drinking hot coffee!). And in semiconductors or undersea fiberoptic transmission lines, the thermal expansion of insulating materials should match that of the functional materials to avoid impeding signal transmission.

    Zaliznyak notes that an underconstrained open framework architecture like that in ScF3 is also present in copper-oxide and iron-based superconductors—where crystal lattice vibrations are thought to play a role in these materials’ ability to carry electric current with no resistance.

    “The independent oscillation of atoms in these open-framework structures may contribute to these materials’ properties in ways we can now calculate and understand,” Zaliznyak said. “They might actually explain some of our own experimental observations that still remain a mystery in these superconductors,” he added.

    “This work profoundly benefitted from the important advantages of the DOE national laboratories—including unique DOE facilities and our ability to have long-time-span projects where important contributions accumulate over time to culminate in a discovery,” Zaliznyak said. “It represents the unique confluence of different expertise among the coauthors, including a dedicated high-school student intern, which we were able to integrate synergistically for this project. It would not have been possible to successfully carry out this research without the expertise provided by all the team members.”

    Brookhaven Lab’s role in this work was funded by the DOE Office of Science.

    See the full article here .


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    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 3:21 pm on November 8, 2019 Permalink | Reply
    Tags: "Tethered Chem Combos Could Revolutionize Artificial Photosynthesis", , “You just dip the electrode coated with the chromophores into a solution in which the catalyst is suspended and the tethers on the two types of molecules find one another and link up”, BNL, , Getting hydrogen atoms to recombine as pure hydrogen gas (H2) is a step toward solar-powered clean-fuel generation., Production of hydrogen gas fuel via artificial photosynthesis and a platform for testing different combos to further improve efficiency.   

    From Brookhaven National Lab: “Tethered Chem Combos Could Revolutionize Artificial Photosynthesis” 

    From Brookhaven National Lab

    November 4, 2019
    Karen McNulty Walsh,
    kmcnulty@bnl.gov
    (631) 344-8350

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

    New approach improves efficiency of converting sunlight to hydrogen fuel; provides platform for testing different combos of light-absorbers and catalysts.

    1
    Brookhaven Lab chemist Javier Concepcion and Lei Wang, a graduate student at Stony Brook University, devised a scheme for assembling light-absorbing molecules and water-splitting catalysts on a nanoparticle-coated electrode. The result: production of hydrogen gas fuel via artificial photosynthesis and a platform for testing different combos to further improve efficiency.

    Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have doubled the efficiency of a chemical combo that captures light and splits water molecules so the building blocks can be used to produce hydrogen fuel. Their study, selected as an American Chemical Society “Editors’ Choice” that will be featured on the cover* of the Journal of Physical Chemistry C, provides a platform for developing revolutionary improvements in so-called artificial photosynthesis—a lab-based mimic of the natural process aimed at generating clean energy from sunlight.

    In natural photosynthesis, green plants use sunlight to transform water (H2O) and carbon dioxide (CO2) into carbohydrates such as sugar and starches. The energy from the sunlight is stored in the chemical bonds holding those molecules together.

    Many artificial photosynthesis strategies start by looking for ways to use light to split water into its constituents, hydrogen and oxygen, so the hydrogen can later be combined with other elements—ideally the carbon from carbon dioxide—to make fuels. But even getting the hydrogen atoms to recombine as pure hydrogen gas (H2) is a step toward solar-powered clean-fuel generation.

    To achieve water splitting, scientists have been exploring a wide range of light-absorbing molecules (also called chromophores, or dyes) paired with chemical catalysts that can pry apart water’s very strong hydrogen-oxygen bonds. The new approach uses molecular “tethers”—simple carbon chains that have a high affinity for one another—to attach the chromophore to the catalyst. The tethers hold the particles close enough together to transfer electrons from the catalyst to the chromophore—an essential step for activating the catalyst—but keeps them far enough apart that the electrons don’t jump back to the catalyst.


    Generating fuel from sunlight: First, tin oxide (SnO2) nanoparticles get coated with a titanium dioxide (TiO2) shell. Next, scientists coat the nanoparticles with light-absorbing dye molecules that have dangling tethers. Then they add catalyst molecules that attach by their own tethers. In the final setup, sunlight excites the dye, kicking electrons from dye to nanoparticle shell, nanoparticle core, and then out of the electrode via a wire. The electron-deficient dye, in turn, grabs electrons from the catalyst. Once the catalyst has lost four electrons, it can steal four electrons from two water molecules, thereby splitting water into hydrogen ions and oxygen. At a second electrode, the hydrogen ions recombine with electrons to produce H2 — hydrogen gas fuel. Animation credit: Stony Brook University graduate student and study coauthor Lei Wang

    “Electrons move fast, but chemical reactions are much slower. So, to give the system time for the water-splitting reaction to take place without the electrons moving back to the catalyst, you have to separate those charges,” explained Brookhaven Lab chemist Javier Concepcion, who led the project.

    In the complete setup, the chromophores (tethered to the catalyst) are embedded in a layer of nanoparticles on an electrode. Each nanoparticle is made of a core of tin dioxide (SnO2) surrounded by a titanium dioxide (TiO2) shell. These different components provide efficient, stepwise shuttling of electrons to keep pulling the negatively charged particles away from the catalyst and sending them to where they are needed to make fuel.

    Here’s how it works from start to finish: Light strikes the chromophore and gives an electron enough of a jolt to send it from the chromophore to the surface of the nanoparticle. From there the electron moves to the nanoparticle core, and then out of the electrode through a wire. Meanwhile, the chromophore, having lost one electron, pulls an electron from the catalyst. As long as there’s light, this process repeats, sending electrons flowing from catalyst to chromophore to nanoparticle to wire.

    Each time the catalyst loses four electrons, it becomes activated with a big enough positive charge to steal four electrons from two water molecules. That breaks the hydrogen and oxygen apart. The oxygen bubbles out as a gas (in natural photosynthesis, this is how plants make the oxygen we breathe!) while the hydrogen atoms (now ions because they are positively charged) diffuse through a membrane to another electrode. There they recombine with the electrons carried by the wire to produce hydrogen gas—fuel!

    Building on experience

    The Brookhaven team had tried an earlier version of this chromophore-catalyst setup [ACS Energy Letters] where the light-absorbing dye and catalyst particles were connected much more closely with direct chemical bonds instead of tethers.

    “This was very difficult to do, taking many steps of synthesis and purification, and it took several months to make the molecules,” Concepcion said. “And the performance was not that good in the end.”

    In contrast, attaching the carbon-chain tethers to both molecules allows them to self-assemble.

    “You just dip the electrode coated with the chromophores into a solution in which the catalyst is suspended and the tethers on the two types of molecules find one another and link up,” said Stony Brook University graduate student Lei Wang, a coauthor on the current paper and lead author on a paper published earlier this year [Journal of the American Chemical Society] that described the self-assembly strategy.

    The new paper includes data showing that the system with tethered connections is considerably more stable than the directly connected components, and it generated twice the amount of current—the number of electrons flowing through the system.

    “The more electrons you generate from the light coming in, the more you have available to generate hydrogen fuel,” Concepcion said.

    The scientists also measured the amount of oxygen produced.

    “We found that this system, using visible light, is capable of reaching remarkable efficiencies for light-driven water splitting,” Concepcion said.

    But there’s still room for improvement, he noted. “What we’ve done to this point works to make hydrogen. But we would like to move to making higher value hydrocarbon fuels.” Now that they have a system where they can easily interchange components and experiment with other variables, they are set to explore the possibilities.

    “One of the most important aspects of this setup is not just the performance, but the ease of assembly,” Concepcion said.

    “Because these combinations of chromophores and catalysts are so easy to make, and the tethers give us so much control over the distance between them, now we can study, for example, what is the optimal distance. And we can do experiments combining different chromophores and catalysts without having to do much complex synthesis to find the best combinations,” he said. “The versatility of this approach will allow us to do fundamental studies that would not have been possible without this system.”

    This research was funded by the DOE Office of Science and was conducted in collaboration with scientists from the Alliance for Molecular PhotoElectrode Design for Solar Fuels EFRC, a DOE Office of Science Energy Frontier Research Center at the University of North Carolina, Chapel Hill. UNC scientists provided the core-shell nanoparticles. Design and synthesis of the system were done at Brookhaven Lab; transient kinetics and photoelectrochemistry studies were carried out at UNC.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


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    BNL NSLS-II


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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 12:26 pm on November 1, 2019 Permalink | Reply
    Tags: "A Superconductor That "Remembers" its Electronic Charge Arrangement", A cuprate known as LBCO for the compounds it contains: lanthanum; barium; copper; and oxygen., , BNL, CDW-charge density wave, , HTSCs-high-temperature superconductors, ,   

    From Brookhaven National Lab: “A Superconductor That “Remembers” its Electronic Charge Arrangement” 

    From Brookhaven National Lab

    October 30, 2019
    Laura Mgrdichian
    mgrdichian@gmail.com

    New information on charge order in a high-temperature superconductor may lead to a fuller understanding of these materials’ electronic behavior.

    1
    The Coherent Soft X-ray Scattering (CSX) beamline at NSLS-II offers the researchers the right tools to probe charge ordering phenomena in quantum materials such as high-temperature superconductors with unprecedented precision. The researcher here aside the CSX scattering station are Stuart Wilkins (left) and Xiaoqian Chen, Mark Dean, Andi Barbour and Vivek Thampy (right from back to front). Other co-authors not shown include X-Ray Scattering Group Leader Ian Robinson and Neutron Scattering Group Leader John Tranquada.

    In the field of superconductivity – the ability of a material to conduct electricity with virtually zero resistance – the so-called high-temperature superconductors (HTSCs) are possible candidates for a new generation of advanced technologies. One subset of these, the “cuprates,” which are crystalline materials based on planes of copper oxide, are particularly promising. But scientists still need to learn much more about these materials before mainstream, room-temperature applications are possible. Currently, even the “high-temperature” superconductors must be chilled to very, very cold temperatures by everyday standards.

    Working at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, researchers from Brookhaven and University College London recently discovered something new and very surprising about one type of periodic electric charge arrangement, which coexists with superconductivity in cuprates, known as a charge density wave (CDW). They found that the specific CDW order within their sample was “remembered” when the sample was repeatedly heated past the temperature where the CDW disappears. This discovery opens a new avenue of research into how these intriguing materials work, bringing scientists one step closer to a complete picture of electronic behavior in cuprates.

    “It would be like melting a pile of ice cubes and then refreezing them – and discovering that they refroze into an identical pile of cubes, even down at the microscopic level,” explained Brookhaven Lab physicist Claudio Mazzoli, one of the researchers involved in the study. “Nobody would expect to see that.”

    Mazzoli and his co-researchers describe their work in the March 29, 2019 online edition of Nature Communications.

    The electronic behavior of the cuprates, as with all HTSCs, is quite complex. As the name implies, the electrons that make up a CDW form a periodic standing-wave pattern. CDWs have been observed in nearly all the cuprates, but their role in superconductivity is still not fully understood. Do they compete with superconductivity? Do they participate in it? Do they hinder superconductivity in certain ways and possibly add to it in others? Scientists are still working this out.

    “In the HTSCs, any arrangement of electrons is of interest to researchers,” said Brookhaven physicist Mark Dean, another of the paper’s authors. “The goal is to investigate these arrangements and tune them – or perhaps remove them – so that the superconducting transition temperature of the material can approach, or maybe surpass, room temperature. To do this, we must learn as much as we can about the electrons’ behavior and their structures in HTSCs.”

    2
    Claudio Mazzoli (left) and Mark Dean (right) used the TARDIS experimental chamber at NSLS-II’s Coherent Soft X-ray Scattering (CSX) beamline to investigate the behavior of charge density waves in a specific high-temperature superconductor.

    One thing that researchers do know is that cuprates containing the same copper oxide planes – but arranged in a slightly different way – may have CDWs with dramatically different properties. It seems, then, that the part of the crystal lattice that hosts the CDW has an effect on the CDW.

    Here, the group set out to learn more about the relationship between the material’s lattice structure and CDW behavior. Their model system was a cuprate known as LBCO for the compounds it contains: lanthanum, barium, copper, and oxygen. LBCO has a transition temperature – the temperature below which it displays the CDW, and above which it does not – of 54 degrees Kelvin (K) (although equivalent to about -360 degrees Fahrenheit, this temperature is still relatively high in the superconductor world).

    The group wanted to find out how imperfections in the LBCO crystal lattice can stabilize the CDW. They were interested in a well-known lattice distortion that occurs in the material: a tilt in the octahedral shape formed by bound copper and oxygen atoms. This tilt tends to anchor the CDW to the lattice such that it orients in a certain direction; it appears that the CDW may be sensitive to the spatial inhomogeneities, or domains, of the lattice. This relationship between the CDW and the domains, as suggested by the temperature behavior uncovered in this study, may be unique to LBCO. It will be very important to understand whether this is a general feature of the cuprates.

    The group cycled their LBCO sample through a range of temperatures, repeatedly heating and cooling it, while probing it with x-rays at Brookhaven’s National Synchrotron Light Source II (NSLS-II), a DOE Office of Science User Facility. At the Coherent Soft X-Ray Scattering (CSX) beamline, they used a technique known as coherent resonant x-ray diffraction, in which x-rays scatter from different domains in the CDW spatial arrangement, interfere with each other, and form a “speckle” pattern that is captured by a special camera. Analyzing this pattern yields information on the CDW’s features.

    3
    The schematic shows how a speckle pattern is measured: first the coherent x-ray beam delivered by the beamline is focused onto the sample, then the x-rays are scattered by the sample at a specific angle (sensitive to the charge density wave presence)and captured by the CCD detector. The pinhole provides a mask, allowing the researchers to illuminate only a small, specific area of the sample.

    This task – directly observing a CDW while tracking its changes, over a range of temperatures – is collectively very challenging, in large part due to the very short distances that characterize the features of a CDW. NSLS-II is uniquely suited to this type of investigation due to the coherent nature of the light it produces, meaning the light waves travel in unison rather than out-of-sync and jumbled. Older light sources do not have such highly coherent beams.

    The speckle analysis revealed that the specific CDW order present below 54 K returned even when the sample was repeatedly cycled through much higher temperatures, up to about 240 K (about -28 °F). The researchers think that the structural changes that take place in the crystal below 240 K create a “pinning landscape” that anchors the CDW to the lattice.

    “Our work opens a new route for studying the complex interplay between charge and lattice degrees of freedom in superconducting cuprates,” said the paper’s lead author, Xiaoqian Chen, a researcher in Brookhaven’s Condensed Matter Physics and Materials Science Department at the time this study was performed (she is now working at Lawrence Berkeley National Laboratory). “It is also a great demonstration of how NSLS-II can be used to study quantum phases of materials and their spectacular, unexpected properties.”

    “This result emphasizes the vital importance of the role of nanoscale domains in high-temperature superconductivity. Without the domain pinning effects that have been observed, the CDW might carry current and further disrupt the superconductivity,” added co-author Ian Robinson, a physicist at Brookhaven as well as at University College London. “Imaging these subtle ‘phase’ domain structures is still in its infancy and this work highlights the need to develop better imaging techniques so that structural details can be seen directly.”

    The preparation of the sample used in this study was done at Brookhaven’s Center for Functional Nanomaterials. Additionally, a small portion of this work was performed at Argonne National Laboratory’s Advanced Photon Source. Both are DOE Office of Science User Facilities.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


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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 3:08 pm on October 25, 2019 Permalink | Reply
    Tags: , , BNL, NSLS II Celebrates its 5th Anniversary   

    From Brookhaven National Lab: “NSLS-II Celebrates its 5th Anniversary” 

    From Brookhaven National Lab

    October 23, 2019
    Stephanie Kossman
    skossman@bnl.gov

    In just five years, 28 beamlines came online, over 1,800 different experiments ran, and nearly 3,000 scientists conducted research at the National Synchrotron Light Source II.

    1
    An aerial view of NSLS-II. The facility is large enough to fit Yankee Stadium inside its half-mile-long ring.

    On this day five years ago, the National Synchrotron Light Source II (NSLS-II) achieved “first light”—its first successful delivery of x-ray beams. Signaling the start of operations at NSLS-II—one of the world’s most advanced synchrotron light sources—Oct. 23, 2014 marked a new era of synchrotron science.

    “It is astonishing to me how much we have accomplished in just five years,” said NSLS-II Director John Hill. “Every day when I come to work, I am proud of what we have achieved through the expertise, dedication and passion that everyone here brings to NSLS-II.”

    The legacy of light sources at Brookhaven Lab

    Synchrotron light sources like NSLS-II produce extremely intense light (from infrared to x-rays), which scientists can use to “see” the inner structural, chemical, and electronic makeup of materials, down to the atomic scale. From protein structures to chemical processes in batteries, light sources illuminate scientific mysteries of all kinds. But in decades past, this ultrabright light could only be produced as a byproduct of particle accelerators and it was widely considered to be a nuisance.

    As the scientific value of ultrabright synchrotron light became well-recognized in the early 1970s, two scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, Renate Chasman and G. Kenneth Green, pushed the field forward by developing a novel magnet configuration for synchrotron storage rings that optimized the brightness of light sources. Their design became the basis for Brookhaven’s National Synchrotron Light Source (NSLS), NSLS-II’s predecessor, and later led to the rapid growth of major light source facilities around the world.

    NSLS was one of the first research facilities designed and built specifically for producing ultrabright light or “synchrotron radiation.” NSLS was also the first DOE facility dedicated to “user” research; rather than tackling a single large scientific question, NSLS served many users who conducted individual experiments and came from diverse areas of science and the world. The model gave birth to the DOE Office of Science User Facility program and, ultimately, research at NSLS was awarded two Nobel Prizes.

    2
    An aerial view of NSLS when the facility was still running. Today, the building is the home of Brookhaven Lab’s Computational Science Initiative.

    Building on the legacy of NSLS, NSLS-II was designed to deliver x-rays 10,000 times brighter than its predecessor. The key to the upgraded design is NSLS-II’s half-mile-long accelerator ring that enables the facility to produce extremely narrow x-ray beams. At its largest point, the beam at NSLS-II is only a few dozen microns wide—the width of a human hair. NSLS-II’s advanced accelerator design also provides unprecedented beam stability, giving the facility a world record for beam spot size and opening doors to many new types of scientific experiments.

    Five years of growth and success at NSLS-II

    In NSLS-II’s first five years, scientists and engineers came together to bring 28 experimental stations, called beamlines, into operations, building out nearly half of the facility’s experimental floor. That means that at any given time, 28 different experiments can run simultaneously at NSLS-II. When the facility is fully built out, NSLS-II will accommodate up to 60 different experiments at once.

    3
    How the National Synchrotron Light Source II works. In a synchrotron light source, a “beamline” is a long pipe in which light travels outwards from the facility’s storage ring, where electrons circulate at nearly the speed of light. At NSLS-II, each beamline connects to two hutches: the optical hutch, where scientists can adjust the light to their experiment’s specifications, and the experimental hutch, where scientists set up their samples to be illuminated by the light.

    NSLS-II’s large capacity for beamlines not only enables more scientists to access the facility’s ultrabright light at once, but it also provides the space and flexibility needed to develop highly specialized scientific instruments that accommodate unique and difficult-to-run experiments.

    One of the most notable of these highly specialized beamlines at NSLS-II is the Hard X-ray Nanoprobe (HXN). Housed in its own satellite building that was specially constructed to provide extraordinary stability, HXN gave NSLS-II a world record for beam spot size and offers world-leading spatial resolution to users. The beamline enables scientists to investigate everything from microelectronics to cell membranes.

    3
    The Hard X-ray Nanoprobe (HXN) at NSLS-II.

    Another remarkable beamline that is unique to NSLS-II is the Soft Inelastic X-ray Scattering (SIX) beamline. Like HXN, SIX is also enclosed in its own satellite building, but for a different reason. This beamline is built with a 50-foot-long spectrometer arm that moves from one end of the building to the other, providing world-leading energy resolution. The beamline’s design enables scientists to probe the electronic structure of materials to advance research on quantum materials and superconductors.

    4
    The Soft Inelastic X-ray Scattering (SIX) beamline at NSLS-II.

    With so many specialized and world-class tools available at NSLS-II, visiting researchers can benefit by taking their experiments to multiple beamlines to compare and combine datasets and achieve a more holistic view of their samples.

    “NSLS-II recognizes the need for comprehensive studies on materials, which means researchers need to use more than one technique to uncover the properties and behaviors of materials,” Hill said. “I am very pleased that our users can now request multiple beamlines on a single proposal, what we call a ‘multimodal’ proposal.”

    From biology to materials science, researchers from all areas of science have come to NSLS-II to take advantage of these capabilities. In the facility’s first five years, staff scientists and visiting researchers have unlocked new protein structures, studied nanoscale phenomena in electronic and information technologies, studied energy materials across multiple length and time scales at once, and watched chemical catalysts work in real-time.

    Sometimes, the images produced at NSLS-II are as beautiful as they are informative. Earlier this year, scientists at Carnegie Mellon University collaborated with NSLS-II to determine how nanomaterials could be used to tackle global food security challenges. Using the Submicron Resolution X-ray Spectroscopy (SRX) beamline and the X-ray Fluorescence Microprobe (XFM) beamline, the team produced images in which key elements in crop samples fluoresced. By studying these images, the scientists were able to determine how nanoparticles influenced the movement of metals throughout the crops, suggesting ways to target the delivery of nutrients to specific plant organs.

    5
    Data images produced by XFM. (Left) Data from the Carnegie Mellon research described above. (Right) Scans of a leaflet of P. vittata (an arsenic hyperaccumulator) from an additional study, showing the concentrations of potassium (green), arsenic (red), and calcium (blue).

    In March, scientists at NSLS-II identified the cause of battery cathode degradation in nickel-rich materials. The team used the Inner-Shell Spectroscopy (ISS) and X-ray Powder Diffraction (XPD) beamlines at NSLS-II to “see” the chemical environment around nickel atoms in a cathode material, and determined inhomogeneities in nickel’s oxidation states led to the degradation. Their work could help improve lithium-ion batteries, which are used to power everything from consumer electronics to electric vehicles.

    6
    Brookhaven chemists and NSLS-II scientists are shown at the ISS beamline, where the battery research was conducted. Pictured from front to back are Eli Stavitski, Xiao-Qing Yang, Xuelong Wang, and Enyuan Hu.

    In addition to collaborating with universities and other national laboratories on individual studies, NSLS-II has established strong working relationships with outside institutions to fund and operate new beamlines at the facility. For example, the National Institute of Standards and Technology owns and operates three beamlines at NSLS-II that enable scientists to “see” detailed views of chemical reactions. Case Western Reserve University operates one beamline and collaborates with NSLS-II on two additional beamlines to provide scientists with a suite of biological imaging endstations. One of NSLS-II’s most notable partnerships, however, is with Brookhaven’s own Center for Functional Nanomaterials (CFN), another DOE Office of Science User Facility. CFN currently operates three beamlines in partnership with NSLS-II that are specialized for characterizing nanomaterials.

    New science on the horizon

    In the years to come, scientific collaborations will continue to be key for NSLS-II. For example, a new cryo-electron microscope (cryo-EM) center funded by New York State, called the Laboratory of Biomolecular Structure (LBMS), is currently under construction at Brookhaven Lab, adjacent to NSLS-II. Combining the suite of biological beamlines at NSLS-II with the cryo-EMs at LBMS will offer researchers complementary techniques to study biological systems. The goal is to reveal unprecedented information on the structure and dynamics of the engines of life.

    Also under construction at NSLS-II is a new beamline funded by the New York State Energy Research and Development Authority, called the High Energy Engineering X-Ray Scattering (HEX) beamline. HEX will be a powerful and versatile tool to advance energy storage and conversion research, such as battery development and materials engineering. The beamline will provide extremely energetic x-rays that can penetrate steel casings of full-size batteries so scientists can image atomic structures under working conditions and in real time.

    “Looking to the future, I see NSLS-II becoming an even larger hub for materials characterization of all kinds,” Hill said. “Our high-end beamlines and expert staff offer many opportunities for partnerships and collaborations. At the end of the day, this is what makes our science strong: the brightest minds, together, focusing on the biggest challenges in 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 11:51 am on October 4, 2019 Permalink | Reply
    Tags: BNL, , , Quantum Astrometry   

    From Brookhaven National Lab: “Department of Energy Announces $21.4 Million for Quantum Information Science Research” 

    From Brookhaven National Lab

    October 1, 2019
    Ariana Manglaviti,
    amanglaviti@bnl.gov
    (631) 344-2347, or

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

    Projects linked to both particle physics and fusion energy

    Today, the U.S. Department of Energy (DOE) announced $21.4 million in funding for research in Quantum Information Science (QIS) related to both particle physics and fusion energy sciences.

    “QIS holds great promise for tackling challenging questions in a wide range of disciplines,” said Under Secretary for Science Paul Dabbar. “This research will open up important new avenues of investigation in areas like artificial intelligence while helping keep American science on the cutting edge of the growing field of QIS.”

    Funding of $12 million will be provided for 21 projects of two to three years’ duration in particle physics. Efforts will range from the development of highly sensitive quantum sensors for the detection of rare particles, to the use of quantum computing to analyze particle physics data, to quantum simulation experiments connecting the cosmos to quantum systems.

    Funding of $9.4 million will be provided for six projects of up to three years in duration in fusion energy sciences. Research will examine the application of quantum computing to fusion and plasma science, the use of plasma science techniques for quantum sensing, and the quantum behavior of matter under high-energy-density conditions, among other topics.

    Fiscal Year 2019 funding for the two initiatives totals $18.4 million, with out-year funding for the three-year particle physics projects contingent on congressional appropriations.

    Projects were selected by competitive peer review under two separate Funding Opportunity Announcements (and corresponding announcements for DOE laboratories) sponsored respectively by the Office of High Energy Physics and the Office of Fusion Energy Sciences with the Department’s Office of Science.

    A list of particle physics projects can be found here and fusion energy sciences projects here, both under the heading “What’s New.”

    Quantum Convolutional Neural Networks for High-Energy Physics Data Analysis

    1
    (From left to right) Brookhaven computational scientist Shinjae Yoo (principal investigator), Brookhaven physicist Chao Zhang, and Stony Brook University quantum information theorist Tzu-Chieh Wei are developing deep learning techniques to efficiently handle sparse data using quantum computer architectures. Data sparsity is common in high-energy physics experiments.

    Over the past few decades, the scale of high-energy physics (HEP) experiments and size of data they produce have grown significantly. For example, in 2017, the data archive of the Large Hadron Collider (LHC) at CERN in Europe—the particle collider where the Higgs boson was discovered—surpassed 200 petabytes.

    CERN LHC

    CERN CMS Higgs Event May 27, 2012


    CERN ATLAS Higgs Event

    For perspective, consider Netflix streaming: a 4K movie stream uses about seven gigabytes per hour, so 200 petabytes would be equivalent to 3,000 years of 4K streaming. Data generated by future detectors and experiments such as the High-Luminosity LHC, the Deep Underground Neutrino Experiment (DUNE), Belle II, and the Large Synoptic Survey Telescope (LSST) will move into the exabyte range (an exabyte is 1,000 times larger than a petabyte).

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    Belle II KEK High Energy Accelerator Research Organization Tsukuba, Japan

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    These large data volumes present significant computing challenges for simulating particle collisions, transforming raw data into physical quantities such as particle position, momentum, and energy (a process called event reconstruction), and performing data analysis. As detectors become more sensitive, simulation capabilities improve, and data volumes increase by orders of magnitude, the need for scalable data analytics solutions will only increase.

    A viable solution could be QIS. Quantum computers and algorithms have the capability to solve problems exponentially faster than classically possible. The Quantum Convolutional Neural Networks (CNNs) for HEP Data Analysis project will exploit this “quantum advantage” to develop machine learning techniques for handling data-intensive HEP applications. Neural networks refer to a class of deep learning algorithms that are loosely modelled on the architecture of neuron connections in the human brain. One type of neural network is the CNN, which is most commonly used for computer vision tasks, such as facial recognition. CNNs are typically composed of three types of layers: convolution layers (convolution is a linear mathematical operation) that extract meaningful features from an image, pooling layers that reduce the number of parameters and computations, and fully connected layers that classify the extracted features into a label.

    In this case, the scientists on the project will develop a quantum-accelerated CNN algorithm and quantum memory optimized to handle extremely sparse data. Data sparsity is common in HEP experiments, for which there is a low probability of producing exotic and interesting signals; thus, rare events must be extracted from a much larger amount of data. For example, even though the size of the data from one DUNE event could be on the order of gigabytes, the signals represent one percent or less of those data. They will demonstrate the algorithm on DUNE data challenges, such as classifying images of neutrino interactions and fitting particle trajectories. Because the DUNE particle detectors are currently under construction and will not become operational until the mid-2020s, simulated data will be used initially.

    4
    Neutrino interaction events are characterized by extremely sparse data, as can be seen in the above 3-D image reconstruction from 2-D measurements.

    “Customizing a CNN to work efficiently on sparse data with a quantum computer architecture will not only benefit DUNE but also other HEP experiments,” said principal investigator Shinjae Yoo, a computational scientist in the Computer Science and Mathematics Department of Brookhaven Lab’s Computational Science Initiative (CSI).

    The co-investigator is Brookhaven physicist Chao Zhang. Yoo and Zhang will collaborate with quantum information theorist Tzu-Chieh Wei, an associate professor at Stony Brook University’s C.N. Yang Institute for Theoretical Physics.

    Quantum Astrometry

    3
    (Left photo, left to right) Brookhaven Lab physicists Paul Stankus, Andrei Nomerotski (principal investigator), Sven Herrmann, and (right photo) Eden Figueroa (a Stony Brook University joint appointee) are developing a new quantum technique that will enable more precise measurements for studies in astrophysics and cosmology. They will use a fiber-coupled telescope with adaptive optics (seen in left photo) for the proof-of-principle measurements.

    The resolution of any optical telescope is fundamentally limited by the size of the aperture, or the opening through which particles of light (photons) are collected, even after the effects of atmospheric turbulence and other fluctuations have been corrected for. Optical interferometry—a technique in which light from multiple telescopes is combined to synthesize a large aperture between them—can improve resolution. Though interferometers can provide the clearest images of very small astronomical objects such as distant galaxies, stars, and planetary systems, the instruments’ intertelescope connections are necessarily complex. This complexity limits the maximum separation distance (“baseline”)—and hence the ultimate resolution.

    An alternative approach to overcoming the aperture resolution limit is to quantum mechanically interfere star photons with distributed entangled photons at separated observing locations. This approach exploits the phenomenon of quantum entanglement, which occurs when two particles such as photons are “linked.” Though these pairs are not physically connected, measurements involving them remain correlated regardless of the distance between them.

    5
    Schematic of two-photon interferometry. If the two photons are close enough together in time and frequency, the pattern of coincidences between measurements at detectors c and d in L and detectors g and h in R will be sensitive to the phase differences. The phase differences from each source can be related to their angular position in the sky.

    The Quantum Astrometry project seeks to exploit this phenomenon to develop a new quantum technique for high-resolution astrometry—the science of measuring the positions, motions, and magnitudes of celestial objects—based on two-photon interferometry. In traditional optical interferometry, the optical path for the photons from the telescopes must be kept highly stable, so the baseline for today’s interferometers is about 100 meters. At this baseline, the resolution is sufficient to directly see exoplanets or track stars orbiting the supermassive black hole in the center of the Milky Way. One goal of quantum astrometry is to reduce the demands for intertelescope links, thereby enabling longer baselines and higher resolutions.

    Pushing the resolution even further would allow more precise astrometric measurements for studies in astrophysics and cosmology. For example, black hole accretion discs—flat astronomical structures made up of a rapidly rotating gas that slowly spirals inward—could be directly imaged to test theories of gravity. An orders-of-magnitude higher resolution would also enable scientists to refine measurements of the expansion rate of the universe, map gravitational microlensing events (temporary brightening of distant objects when light is bent by another object passing through our line of sight) to probe the nature of dark matter (a type of “invisible” matter thought to make up most of the universe’s mass), and measure the 3-D “peculiar” velocities of stars (their individual motion with respect to that of other stars) across the galaxy to determine the forces acting on all stars.

    In classical interferometry, photons from an astronomical source strike two telescopes with some relative delay (phase difference), which can be determined through interference of their intensities. Using two photons in the form of entangled pairs that can transmit simultaneously to both stations and interfere with the star photons would allow arbitrarily long baselines and much finer resolution on this relative phase difference and hence on astrometry.

    “This is a very exploratory project where for the first time we will test ideas of two-photon optical interferometry using quantum entanglement for astronomical observations,” said principal investigator Andrei Nomerotski, a physicist in the Lab’s Cosmology and Astrophysics Group. “We will start with simple proof-of-principle experiments in the lab, and in two years, we hope to have a demonstrator with real sky observations.

    “It’s an example of how quantum techniques can open new ranges for scientific sensors and detectors,” added Paul Stankus, a physicist in Brookhaven’s Instrumentation Division who is working on QIS.

    The other team members are Brookhaven physicist Sven Herrmann, a collaborator on several astrophysics projects, including LSST, and Brookhaven–Stony Brook University joint appointee Eden Figueroa, a leading figure in quantum communication technology.

    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 12:28 pm on September 13, 2019 Permalink | Reply
    Tags: , BNL, CBETA-Cornell-Brookhaven “Energy-Recovery Linac” Test Accelerator or, , , Innovative particle accelerator, , ,   

    From Brookhaven National Lab & Cornell University: “Innovative Accelerator Achieves Full Energy Recovery” 

    From Brookhaven National Lab

    September 10, 2019
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    Collaborative Cornell University/Brookhaven Lab project known as CBETA offers promise for future accelerator applications.

    1
    Brookhaven Lab members of the CBETA team with Laboratory Director Doon Gibbs, front row, right.

    An innovative particle accelerator designed and built by scientists from the U.S. Department of Energy’s Brookhaven National Laboratory and Cornell University has achieved a significant milestone that could greatly enhance the efficiency of future particle accelerators. After sending a particle beam for one pass through the accelerator, machine components recovered nearly all of the energy required for accelerating the particles. This recovered energy can then be used for the next stage of acceleration—to accelerate another batch of particles—thus greatly reducing the potential cost of accelerating particles to high energies.

    “No new power is required to maintain the radiofrequency (RF) fields in the RF cavities used for acceleration, because the accelerated beam deposits its energy in the RF cavities when it is decelerated,” said Brookhaven Lab accelerator physicist Dejan Trbojevic, who led the design and construction of key components for the project and serves as the Principal Investigator for Brookhaven’s contributions.

    The prototype accelerator—known as the Cornell-Brookhaven ERL Test Accelerator (CBETA), where ERL stands for “energy-recovery linac”—was built at Cornell with funding from Brookhaven Science Associates (the managing entity of Brookhaven Lab) and the New York State Energy Research and Development Authority (NYSERDA) as a research and development project in support of a possible future nuclear physics facility, the Electron-Ion Collider (EIC). The energy-recovery approach could play an essential role in generating reusable electron beams for enhancing operations at a future EIC. The electrons would reduce the spread of ion beams in the EIC, thus increasing the number of particle collisions scientists can record to make physics discoveries.

    2
    Schematic of the CBETA energy recovery linac installed at Cornell University. Electrons produced by a direct-current (DC) photo-emitter electron source are transported by a high-power superconducting radiofrequency (SRF) injector linac into the high-current main linac cryomodule, where SRF cavities accelerate them to high energy before sending them around the racetrack-shaped accelerator. Each curved arc is made of a series of fixed field, alternating gradient (FFA) permanent magnets. After passing through the second FFA arc, the electrons re-enter the main linac cryomodule, which decelerates them and returns their energy to the RF cavities so it can be used again.

    In designing and executing this project, the Brookhaven team drew on its vast experience of improving the performance of the Relativistic Heavy Ion Collider (RHIC), a DOE Office of Science user facility for nuclear physics research.

    BNL/RHIC

    The accelerator technologies being developed for the EIC would push beyond the capabilities at RHIC and open up a new frontier in nuclear physics.

    3
    The injector and main linac cryomodule.

    Tech specs

    CBETA consists of a direct-current (DC) photo-emitter electron source that creates the electron beams to be accelerated. These electrons pass through a high-power superconducting radiofrequency (SRF) injector linac that transports them into a high-current main linac cryomodule (MLC). There, six SRF cavities accelerate the electrons to high energy, sending them around the racetrack-shaped accelerator. Each curved section of the racetrack is a single arc of permanent magnets designed with fixed-field alternating-gradient (FFA) optics that allow a single vacuum tube to accommodate beams at four different energies at the same time. After passing through the second FFA arc, the electrons re-enter the MLC, which has been uniquely optimized to decelerate the particles after a single pass and return their energy to the RF cavities so it can be used again.

    When completed, CBETA will accelerate particles through four complete turns, adding energy with each pass—all of which will be recovered during deceleration after the beams have been used. This will make it the world’s first four-turn superconducting radiofrequency ERL.

    Many scientists and engineers at Brookhaven Lab contributed to the design and construction of the magnets and other components of the accelerator, as well as the electronic devices that monitor the positions of the accelerated and decelerated beams: Francois Meot, Scott Berg, Stephen Brooks, and Nicholaos Tsoupas drove the design of the ERL’s optics; Brookhaven physicists led by Brooks and George Mahler designed, built, measured, and applied corrections to the permanent magnets; and Rob Michnoff led the design and construction of the beam position monitor system.

    “After building and successfully testing prototypes of the magnets, we established a very successful collaboration with Cornell, led by Principal Investigator Georg Hoffstaetter, to build the ERL using the refined fixed-field magnet designs,” Trbojevic said.

    Cornell provided the DC electron injector—the world’s record holder for producing high intensity, low emittance electron beams—which they recommissioned for the CBETA project. A team of young scientists and graduate students, including Adam Bartnik, Colwyn Gulliford, Kirsten Deitrick, and Nilanjan Banerjee, made other essential contributions: successfully commissioning the main linac cryomodule, and preparing the “command scripts”—computer-driven instructions—for running and commissioning the ERL in collaboration with Berg and other Brookhaven physicists.

    4
    Part of one of the fixed field, alternating gradient (FFA) permanent magnet arcs.

    “We hold weekly internet-based collaboration meetings and we had several visits and meetings at Cornell to ensure that the project was reaching the key milestones and that installation was proceeding according to the schedule,” said Michnoff, the Brookhaven Lab project manager.

    In May 2019, the team sent an electron beam with an energy of 42 million electron volts (MeV) through the FFA return loop for the first time. The beam made it through all 200 permanent magnets without the need for a single correction. In early June 2019, an energy scan in the FFA loop showed that the return beamline transported particles of different energies superbly, agreeing very well with the expectations for the design.

    Next, on June 13, the beam was accelerated to 42 MeV, transported through the FFA return loop back to the MLC, where the electrons were decelerated from 42 MeV back to the injection energy of 6 MeV, with the rest of their energy transferred back into the six SRF cavities of the main linac. And on June 24, the CBETA team achieved full energy recovery for the first time—demonstrating that each cavity could accelerate electrons on their second pass through the MLC without requiring additional external power.

    “Each cavity successfully regained the energy it expended in beam acceleration, eliminating or dramatically reducing the power needed to accelerate electrons,” Trbojevic said.

    “The successful demonstration of single-turn energy recovery shows that we are on the path toward creating this first-of-its-kind facility,” Trbojevic said. “The entire team is committed and excited to complete this four-turn energy-recovery linac—one of the most interesting and innovative accelerator physics project in the world today.”

    From Cornell University

    CORNELL LABORATORY FOR ACCELERATOR-BASED SCIENCES AND EDUCATION — CLASSE

    5

    Update on Beam Commissioning

    Cornell physicists, working with Brookhaven National Lab, are constructing a new type of particle accelerator called CBETA at Cornell’s Wilson Lab. This Energy Recovery Linac (ERL) is a test accelerator built with permanent magnets as well as electro magnets.

    How it works: CBETA will recirculate multiple beams of different energies around the accelerator at one time. The electrons will make four accelerating passes around the accelerator, while building up energy as they pass through a cryomodule with superconducting RF (SRF) accelerating structures. In four more passes, they will return to the superconducting cavities that accelerated them and return their energy back to these cavities – hence it is an Energy Recovery Linac (ERL). While this method conserves energy, it also creates beams that are tightly bound and are a factor of 1,000 times brighter than other sources. For more details, please contact the Cornell PI Prof. Georg Hoffstaetter.

    Although linear accelerators (Linac) can have superior beam densities when compared to large circular accelerators, they are exceedingly wasteful due to the beam being discarded after use and can therefore only have an extremely low current compared to ring accelerators. This means that the amount of data collected in one hour in a circular accelerator may take several years to collect in a linear accelerator. In an ERL, the energy is recovered, and the beam current can therefore be as large as in a circular accelerator while its beam density remains as large as in a Linac.

    CBETA: the first multi-turn SRF ERL

    The lynchpin of CBETA’s design is to repeat the acceleration in a SRF cavities four times by recirculating multiple beams at four different energies. The beam with highest energy (150MeV) is to be used for experiments and is then decelerated in the same cavities four times to recapture the beam’s energies into the SRF cavities. Reusing the same cavity multiple times significantly reduces the construction and operational costs of the accelerator. It also means that an accelerator which would span roughly a foot ball field can fit into a single experimental Hall at Cornell’s Wilson Laboratory.

    However, beams of different energies require different amounts of bending, in the same way that it is hard for your car to navigate a sharp bend at 100 miles per hour. Traditional magnet designs are simply unable to keep different beams on the same “track”. Instead, the CBETA design relies on cutting edge Fixed-Field Alternating Gradient (FFAG) magnets to contain all of the beams in a single 3 inch beam pipe. CBETA will be the first SRF ERL with more than one turn and it is also the first project in the history of accelerator physics to implement this new magnet technology in an Energy Recovery Linac.

    The task of creating and controlling eight beams of four different energies in a single accelerating structure sounds daunting. But by leveraging the pre-existing infrastructure and experience of Cornell with the power and expertise of Brookhaven National Laboratory, it will soon become a reality.

    Cornell University has prototyped technology essential for CBETA, including a DC gun and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current CW cryomodule for 70 MeV energy gain, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams, e.g. a beamline for measuring 6-D phase-space densities, a fast wire scanner for beam profiles, and beam loss diagnostics. All these now being used in the contrition of CBETA.

    Within the next several years, CBETA will develop into a powerhouse of accelerator physics and technology, and will be one of the most advanced on the planet (earth). When this prototype ERL is complete and expanded upon, it will be a critical resource to New York State and the nation, propelling high-power accelerator science, enabling applications of many particle accelerators, from biomedical advancement to basic physics and from computer-chip lithography to material science, driving economic development.

    7

    CBETA is composed of 4 main parts:

    -The Photoinjector that creates and prepares high-current electron beams to be injected into the Main Linac Cryomodule (MLC). The photoinjector in turn consists of a laser system that illuminates a photo-emitter cathode to produce electrons within a high-current DC electron source. These electrons traverses an emittance-matching section to produce a high-brightness beam which is then sent thorough the high-power injector cryomodule (ICM) for acceleration to the ERL’s injection energy.

    -The Main Linac Cryomodule (MLC) that accelerates the beam through several passages and then decelerates the beam the same number of times to recapture its energy.

    -The high-power Beam Stop where the electron beam is discarded after most of its energy has been recaptured.
    4 Spreaders and 4 combiners with electro magnets that separate beams at 4 different energies after the MLC to match them into the FFAG return loop and then combine them again before re-entering the MLC.

    -FFAG Magnets residing in the return loop. These cause very strong focusing so that beams with energies that differ by up to a factor 4 can be transported simultaneously.

    Dominant funding for CBETA comes from NYSERDA (2016 to 2020). Important for this agency is that CBETA emphasizes energy savings by its use of energy recovery technology, its application of permanent magnets, and its particle acceleration by superconducting structures. Previous funding came from the NSF (2005 – 2015) for the development of the complete accelerator chain from the source to the main ERL accelerating module, from DOE supporting developments for the LCLS (2014-2015), and from the industrial company ASML (2015-2016) for applications in computer chip lithography.

    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 8:10 am on August 30, 2019 Permalink | Reply
    Tags: Advanced nanolithography, ALD-Atomic layer deposition, , BNL, , EUVL-Extreme ultraviolet lithography, , , PMMA-Polymer poly(methyl methacrylate),   

    From Brookhaven National Lab: “Enhancing Materials for Hi-Res Patterning to Advance Microelectronics” 

    From Brookhaven National Lab

    August 27, 2019
    Ariana Manglaviti
    amanglaviti@bnl.gov
    (631) 344-2347

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

    Scientists at Brookhaven Lab’s Center for Functional Nanomaterials [below] created “hybrid” organic-inorganic materials for transferring ultrasmall, high-aspect-ratio features into silicon for next-generation electronic devices.

    1
    (Left to right): Ashwanth Subramanian, Ming Lu, Kim Kisslinger, Chang-Yong Nam, and Nikhil Tiwale in the Electron Microscopy Facility at Brookhaven Lab’s Center for Functional Nanomaterials. The scientists used scanning electron microscopes to image high-resolution, high-aspect-ratio silicon nanostructures they etched using a “hybrid” organic-inorganic resist.

    To increase the processing speed and reduce the power consumption of electronic devices, the microelectronics industry continues to push for smaller and smaller feature sizes. Transistors in today’s cell phones are typically 10 nanometers (nm) across—equivalent to about 50 silicon atoms wide—or smaller. Scaling transistors down below these dimensions with higher accuracy requires advanced materials for lithography—the primary technique for printing electrical circuit elements on silicon wafers to manufacture electronic chips. One challenge is developing robust “resists,” or materials that are used as templates for transferring circuit patterns into device-useful substrates such as silicon.

    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 used the recently developed technique of infiltration synthesis to create resists that combine the organic polymer poly(methyl methacrylate), or PMMA, with inorganic aluminum oxide. Owing to its low cost and high resolution, PMMA is the most widely used resist in electron-beam lithography (EBL), a kind of lithography in which electrons are used to create the pattern template. However, at the resist thicknesses that are necessary to generate the ultrasmall feature sizes, the patterns typically start to degrade when they are etched into silicon, failing to produce the required high aspect ratio (height to width).

    As reported in a paper published online on July 8 in the Journal of Materials Chemistry C, these “hybrid” organic-inorganic resists exhibit a high lithographic contrast and enable the patterning of high-resolution silicon nanostructures with a high aspect ratio. By changing the amount of aluminum oxide (or a different inorganic element) infiltrated into PMMA, the scientists can tune these parameters for particular applications. For example, next-generation memory devices such as flash drives will be based on a three-dimensional stacking structure to increase memory density, so an extremely high aspect ratio is desirable; on the other hand, a very high resolution is the most important characteristic for future processor chips.

    “Instead of taking an entirely new synthesis route, we used an existing resist, an inexpensive metal oxide, and common equipment found in almost every nanofabrication facility,” said first author Nikhil Tiwale, a postdoctoral research associate in the CFN Electronic Nanomaterials Group.

    Though other hybrid resists have been proposed, most of them require high electron doses (intensities), involve complex chemical synthesis methods, or have expensive proprietary compositions. Thus, these resists are not optimal for the high-rate, high-volume manufacture of next-generation electronics.

    Advanced nanolithography for high-volume manufacturing

    Conventionally, the microelectronics industry has relied upon optical lithography, whose resolution is limited by the wavelength of light that the resist gets exposed to. However, EBL and other nanolithography techniques such as extreme ultraviolet lithography (EUVL) can push this limit because of the very small wavelength of electrons and high-energy ultraviolet light. The main difference between the two techniques is the exposure process.

    “In EBL, you need to write all of the area you need to expose line by line, kind of like making a sketch with a pencil,” said Tiwale. “By contrast, in EUVL, you can expose the whole area in one shot, akin to taking a photograph. From this point of view, EBL is great for research purposes, and EUVL is better suited for high-volume manufacturing. We believe that the approach we demonstrated for EBL can be directly applied to EUVL, which companies including Samsung have recently started using to develop manufacturing processes for their 7 nm technology node.”

    In this study, the scientists used an atomic layer deposition (ALD) system—a standard piece of nanofabrication equipment for depositing ultrathin films on surfaces—to combine PMMA and aluminum oxide. After placing a substrate coated with a thin film of PMMA into the ALD reaction chamber, they introduced a vapor of an aluminum precursor that diffused through tiny molecular pores inside the PMMA matrix to bind with the chemical species inside the polymer chains. Then, they introduced another precursor (such as water) that reacted with the first precursor to form aluminum oxide inside the PMMA matrix. These steps together constitute one processing cycle.

    2
    A schematic showing the process of creating the hybrid organic-inorganic resist through infiltration synthesis, patterning the resist via electron-beam lithography, and etching the pattern into silicon by bombarding the silicon surface with ions of sulfur hexafluoride (SF6).

    The team then performed EBL with hybrid resists that had up to eight processing cycles. To characterize the contrast of the resists under different electron doses, the scientists measured the change in resist thickness within the exposed areas. Surface height maps generated with an atomic force microscope (a microscope with an atomically sharp tip for tracking the topography of a surface) and optical measurements obtained through ellipsometry (a technique for determining film thickness based on the change in the polarization of light reflected from a surface) revealed that the thickness changes gradually with a low number of processing cycles but rapidly with additional cycles—i.e., a higher aluminum oxide content.

    “The contrast refers to how fast the resist changes after being exposed to the electron beam,” explained Chang-Yong Nam, a materials scientist in the CFN Electronic Nanomaterials Group, who supervised the project and conceived the idea in collaboration with Jiyoung Kim, a professor in the Department of Materials Science and Engineering at the University of Texas at Dallas. “The abrupt change in the height of the exposed regions suggests an increase in the resist contrast for higher numbers of infiltration cycles—almost six times higher than that of the original PMMA resist.”

    The scientists also used the hybrid resists to pattern periodic straight lines and “elbows” (intersecting lines) in silicon substrates, and compared the etch rate of the resists with substrates.

    3
    Left: A scanning electron microscope (SEM) image of silicon elbow-shaped nanopatterns with different feature sizes (linewidths). Right: A high-magnification SEM image of high-resolution, high-aspect-ratio silicon nanostructures patterned at a pitch resolution (linewidth plus spacewidth, or space between lines) of 500 nm.

    “You want silicon to be etched faster than the resist; otherwise the resist starts to degrade,” said Nam. “We found that the etch selectivity of our hybrid resist is higher than that of costly proprietary resists (e.g., ZEP) and techniques that use an intermediate “hard” mask layer such as silicon dioxide to prevent pattern degradation, but which require additional processing steps.”

    3
    After two processing cycles, the etch selectivity of the hybrid resist surpasses that of ZEP, a costly resist. After four cycles, the hybrid resist has a 40 percent higher etch selectivity than that of silicon dioxide (SiO2).

    Going forward, the team will study how the hybrid resists respond to EUV exposure. They have already started using soft x-rays (energy range corresponding to the wavelength of EUV light) at Brookhaven’s National Synchrotron Light Source II (NSLS-II) [below], and hope to use a dedicated EUV beamline operated by the Center for X-ray Optics at Lawrence Berkeley National Lab’s Advanced Light Source (ALS) in collaboration with industry partners.

    LBNL ALS

    “The energy absorption by the organic layer of EUVL resists is very weak,” said Nam. “Adding inorganic elements, such as tin or zirconium, can make them more sensitive to EUV light. We look forward to exploring how our approach can address the resist performance requirements of EUVL.”

    Both NSLS-II and ALS are DOE User Facilities.

    The other co-authors are CFN scientists Kim Kisslinger, Ming Lu, and Aaron Stein; and Ashwanth Subramanian, a PhD student in the Department of Materials Science and Chemical Engineering at Stony Brook University and a graduate research assistant at the CFN.

    See the full article here .


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    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.
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