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  • richardmitnick 3:41 pm on May 18, 2018 Permalink | Reply
    Tags: , ORNL, , , PROSPECT-Precision Reactor Oscillation and Spectrum Experiment,   

    From Yale University: “PROSPECTing for antineutrinos” 

    Yale University bloc

    From Yale University

    ORNL

    May 18, 2018
    Jim Shelton
    james.shelton@yale.edu
    203-361-8332

    1
    Assembly of the PROSPECT neutrino detector. (Image credit: PROSPECT collaboration/Mara Lavitt)

    The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) has completed the installation of a novel antineutrino detector that will probe the possible existence of a new form of matter.

    PROSPECT, located at the High Flux Isotope Reactor (HFIR) at the Department of Energy’s Oak Ridge National Laboratory (ORNL), has begun taking data to study electron antineutrinos that are emitted from nuclear decays in the reactor to search for so-called sterile neutrinos and to learn about the underlying nuclear reactions that power fission reactors.

    Antineutrinos are elusive, elementary particles produced in nuclear beta decay. The antineutrino is an antimatter particle, the counterpart to the neutrino.

    “Neutrinos are among the most abundant particles in the universe,” said Yale University physicist Karsten Heeger, principal investigator and co-spokesperson for PROSPECT. “The discovery of neutrino oscillation has opened a window to physics beyond the Standard Model of Physics. The study of antineutrinos with PROSPECT allows us to search for a previously unobserved particle, the so-called sterile neutrino, while probing the nuclear processes inside a reactor.”

    Over the past few years several neutrino experiments at nuclear reactors have detected fewer antineutrinos than scientists had predicted, and the energy of the neutrinos did not match expectations. This, in combination with earlier anomalous results, led to the hypothesis that a fraction of electron antineutrinos may transform into sterile neutrinos that would have remained undetected in previous experiments.

    This hypothesized transformation would take place through a quantum mechanical process called neutrino oscillation. The first observation of neutrino oscillation amongst known types of neutrinos from the sun and the atmosphere led to the 2015 Nobel Prize in physics.

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    (Image credit: PROSPECT collaboration/Mara Lavitt)

    The installation of PROSPECT follows four years of intensive research and development by a collaboration of more than 60 participants from 10 universities and four national laboratories.

    “The development of PROSPECT is based on years of research in the detection of reactor antineutrinos with surface-based detectors, an extremely challenging task because of high backgrounds,” said PROSPECT co-spokesperson Pieter Mumm, a scientist at the National Institute of Standards and Technology (NIST).

    The experiment uses a novel antineutrino detector system based on a segmented liquid scintillator detector technology. The combination of segmentation and a unique, lithium-doped liquid scintillator formulation allows PROSPECT to identify particle types and interaction points. These design features, along with extensive, tailored shielding, will enable PROSPECT to make a precise measurement of neutrinos in the high-background environment of a nuclear reactor.

    PROSPECT’s detector technology also may have applications in the monitoring of nuclear reactors for non-proliferation purposes and the measurement of neutrons from nuclear processes.

    “The successful operation of PROSPECT will allow us to gain insight into one of the fundamental puzzles in neutrino physics and develop a better understanding of reactor fuel, while also providing a new tool for nuclear safeguards,” said co-spokesperson Nathaniel Bowden, a scientist at Lawrence Livermore National Laboratory and an expert in nuclear non-proliferation technology.

    After two years of construction and final assembly at the Yale Wright Laboratory, the PROSPECT detector was transported to HFIR in early 2018.

    “The development and construction of PROSPECT has been a significant team effort, making use of the complementary expertise at U.S. national laboratories and universities,” said Alfredo Galindo-Uribarri, leader of the Neutrino and Advanced Detectors group in ORNL’s Physics Division.

    PROSPECT is the latest in a series of fundamental science experiments located at HFIR. “We are excited to work with PROSPECT scientists to support their research,” said Chris Bryan, who manages experiments at HFIR for ORNL’s Research Reactors Division.

    The experiment is supported by the U.S. Department of Energy Office of Science, the Heising-Simons Foundation, and the National Science Foundation. Additional support comes from Yale University, the Illinois Institute of Technology, and the Lawrence Livermore National Laboratory LDRD program. The collaboration also benefits from the support and hospitality of the High Flux Isotope Reactor, a DOE Office of Science User Facility, and Oak Ridge National Laboratory, managed by UT-Battelle for the U.S. Department of Energy.

    See the full article here .

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    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

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  • richardmitnick 5:42 pm on April 11, 2018 Permalink | Reply
    Tags: , , , , ORNL, ,   

    From Symmetry: “Right on target” 

    Symmetry Mag
    Symmetry

    04/11/18
    Sarah Lawhun

    1
    Patrick Hurh

    These hardy physics components live at the center of particle production.

    For some, a target is part of a game of darts. For others, it’s a retail chain. In particle physics, it’s the site of an intense, complex environment that plays a crucial role in generating the universe’s smallest components for scientists to study.

    The target is an unsung player in particle physics experiments, often taking a back seat to scene-stealing light-speed particle beams and giant particle detectors. Yet many experiments wouldn’t exist without a target. And, make no mistake, a target that holds its own is a valuable player.

    Scientists and engineers at Fermilab [FNAL] are currently investigating targets for the study of neutrinos—mysterious particles that could hold the key to the universe’s evolution.

    Intense interactions

    The typical particle physics experiment is set up in one of two ways. In the first, two energetic particle beams collide into each other, generating a shower of other particles for scientists to study.

    In the second, the particle beam strikes a stationary, solid material—the target. In this fixed-target setup, the powerful meeting produces the particle shower.

    As the crash pad for intense beams, a target requires a hardy constitution. It has to withstand repeated onslaughts of high-power beams and hold up under hot temperatures.

    You might think that, as stalwart players in the play of particle production, targets would look like a fortress wall (or maybe you imagined dartboard). But targets take different shapes—long and thin, bulky and wide. They’re also made of different materials, depending on the kind of particle one wants to make. They can be made of metal, water or even specially designed nanofibers.

    In a fixed-target experiment, the beam—say, a proton beam—races toward the target, striking it. Protons in the beam interact with the target material’s nuclei, and the resulting particles shoot away from the target in all directions. Magnets then funnel and corral some of these newly born particles to a detector, where scientists measure their fundamental properties.

    The particle birthplace

    The particles that emerge from the beam-target interaction depend in large part on the target material. Consider Fermilab neutrino experiments.

    In these experiments, after the protons strike the target, some of the particles in the subsequent particle shower decay—or transform—into neutrinos.

    The target has to be made of just the right stuff.

    “Targets are crucial for particle physics research,” says Fermilab scientist Bob Zwaska. “They allow us to create all of these new particles, such as neutrinos, that we want to study.”

    Graphite is a goldilocks material for neutrino targets. If kept at the right temperature while in the proton beam, the graphite generates particles of just the right energy to be able to decay into neutrinos.

    For neutron targets, such as that at the Spallation Neutron Source at Oak Ridge National Laboratory [ORNL], heavier metals such as mercury are used instead.

    ORNL Spallation Neutron Source


    ORNL Spallation Neutron Source

    Maximum interaction is the goal of a target’s design. The target for Fermilab’s NOvA neutrino experiment, for example, is a straight row—about the length of your leg—of graphite fins that resemble tall dominoes.

    FNAL NOvA Near Detector


    FNAL/NOvA experiment map

    The proton beam barrels down its axis, and every encounter with a fin produces an interaction. The thin shape of the target ensures that few of the particles shooting off after collision are reabsorbed back into the target.

    Robust targets

    “As long as the scientists have the particles they need to study, they’re happy. But down the line, sometimes the targets become damaged,” says Fermilab engineer Patrick Hurh. In such cases, engineers have to turn down—or occasionally turn off—the beam power. “If the beam isn’t at full capacity or is turned off, we’re not producing as many particles as we can for science.”

    The more protons that are packed into the beam, the more interactions they have with the target, and the more particles that are produced for research. So targets need to be in tip-top shape as much as possible. This usually means replacing targets as they wear down, but engineers are always exploring ways of improving target resistance, whether it’s through design or material.

    Consider what targets are up against. It isn’t only high-energy collisions—the kinds of interactions that produce particles for study—that targets endure.

    Lower-energy interactions can have long-term, negative impacts on a target, building up heat energy inside it. As the target material rises in temperature, it becomes more vulnerable to cracking. Expanding warm areas hammer against cool areas, creating waves of energy that destabilize its structure.

    Some of the collisions in a high-energy beam can also create lightweight elements such as hydrogen or helium. These gases build up over time, creating bubbles and making the target less resistant to damage.

    A proton from the beam can even knock off an entire atom, disrupting the target’s crystal structure and causing it to lose durability.

    Clearly, being a target is no picnic, so scientists and engineers are always improving targets to better roll with a punch.

    For example, graphite, used in Fermilab’s neutrino experiments, is resistant to thermal strain. And, since it is porous, built-up gases that might normally wedge themselves between atoms and disrupt their arrangement may instead migrate to open areas in the atomic structure. The graphite is able to remain stable and withstand the waves of energy from the proton beam.

    Engineers also find ways to maintain a constant target temperature. They design it so that it’s easy to keep cool, integrating additional cooling instruments into the target design. For example, external water tubes help cool the target for Fermilab’s NOvA neutrino experiment.

    Targets for intense neutrino beams

    At Fermilab, scientists and engineers are also testing new designs for what will be the lab’s most powerful proton beam—the beam for the laboratory’s flagship Long-Baseline Neutrino Facility and Deep Underground Neutrino Experiment, known as LBNF/DUNE.

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    LBNF/DUNE is scheduled to begin operation in the 2020s. The experiment requires an intense beam of high-energy neutrinos—the most intense in the world. Only the most powerful proton beam can give rise to the quantities of neutrinos LBNF/DUNE needs.

    Scientists are currently in the early testing stages for LBNF/DUNE targets, investigating materials that can withstand the high-power protons. Currently in the running are beryllium and graphite, which they’re stretching to their limits. Once they conclusively determine which material comes out on top, they’ll move to the design prototyping phase. So far, most of their tests are pointing to graphite as the best choice.

    Targets will continue to evolve and adapt. LBNF/DUNE provides just one example of next-generation targets.

    “Our research isn’t just guiding the design for LBNF/DUNE,” Hurh says. “It’s for the science itself. There will always be different and more powerful particle beams, and targets will evolve to meet the challenge.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:02 pm on February 16, 2018 Permalink | Reply
    Tags: , Improving quantum information processing, ORNL   

    From ORNL: “Researchers demonstrate promising method for improving quantum information processing” 

    i1

    Oak Ridge National Laboratory

    February 16, 2018
    Scott Jones, Communications
    jonesg@ornl.gov
    865.241.6491

    1
    Joseph Lukens, Pavel Lougovski and Nicholas Peters (from left), researchers with ORNL’s Quantum Information Science Group, are examining methods for encoding photons with quantum information that are compatible with the existing telecommunications infrastructure and that incorporate off-the-shelf components. Credit: Genevieve Martin/Oak Ridge National Laboratory, U.S. Department of Energy.

    A team of researchers led by the Department of Energy’s Oak Ridge National Laboratory has demonstrated a new method for splitting light beams into their frequency modes. The scientists can then choose the frequencies they want to work with and encode photons with quantum information. Their work could spur advancements in quantum information processing and distributed quantum computing.

    The team’s findings were published in Physical Review Letters.

    The frequency of light determines its color. When the frequencies are separated, as in a rainbow, each color photon can be encoded with quantum information, delivered in units known as qubits. Qubits are analogous to but different from classical bits, which have a value of either 0 or 1, because qubits are encoded with values of both 0 and 1 at the same time.

    The researchers liken quantum information processing to stepping into a hallway and being able to go both ways, whereas in classical computing just one path is possible.

    The team’s novel approach—featuring the first demonstration of a frequency tritter, an instrument that splits light into three frequencies—returned experimental results that matched their predictions and showed that many quantum information processing operations can be run simultaneously without increasing error. The quantum system performed as expected under increasingly complex conditions without degrading the encoded information.

    “Under our experimental conditions, we got a factor 10 better than typical error rates,” said Nicholas Peters, Quantum Communications team lead for ORNL’s Quantum Information Science Group. “This establishes our method as a frontrunner for high-dimensional frequency-based quantum information processing.”

    Photons can carry quantum information in superpositions—where photons simultaneously have multiple bit values—and the presence of two quantum systems in superposition can lead to entanglement, a key resource in quantum computing.

    Entanglement boosts the number of calculations a quantum computer could run, and the team’s focus on creating more complex frequency states aims to make quantum simulations more powerful and efficient. The researchers’ method is also notable because it demonstrates the Hadamard gate, one of the elemental circuits required for universal quantum computing.

    “We were able to demonstrate extremely high-fidelity results right off the bat, which is very impressive for the optics approach,” said Pavel Lougovski, the project’s principal investigator. “We are carving out a subfield here at ORNL with our frequency-based encoding work.”

    The method leverages widely available telecommunications technology with off-the-shelf components while yielding high-fidelity results. Efforts to develop quantum repeaters, which extend the distance quantum information can be transmitted between physically separated computers, will benefit from this work.

    “The fact that our method is telecom network-compatible is a big advantage,” Lougovski said. “We could perform quantum operations on telecom networks if needed.”

    Peters added that their project demonstrates that unused fiber-optic bandwidth could be harnessed to reduce computational time by running operations in parallel.

    “Our work uses frequency’s main advantage—stability—to get very high fidelity and then do controlled frequency jumping when we want it,” said Wigner Fellow Joseph Lukens, who led the ORNL experiment. The researchers have experimentally shown that quantum systems can be transformed to yield desired outputs.

    The researchers suggest their method could be paired with existing beam-splitting technology, taking advantage of the strengths of both and bringing the scientific community closer to full use of frequency-based photonic quantum information processing.

    Peters, Lougovski and Lukens, all physicists with ORNL’s Quantum Information Science Group, collaborated with graduate student Hsuan-Hao Lu, professor Andrew Weiner, and colleagues at Purdue University. The team published the theory for their experiments in Optica in January 2017.

    This research is supported by ORNL’s Laboratory Directed Research and Development program and the National Science Foundation.

    See the full article here .

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 4:40 pm on January 2, 2018 Permalink | Reply
    Tags: , , , Mallory Ladd, Mallory Ladd began trekking to the Arctic even before her time at the Department of Energy's Oak Ridge National Laboratory, NGEE-Arctic program, ORNL, Soil chemistry,   

    From ORNL: Women in STEM- “Mallory Ladd: A molecular-scale Arctic expedition” 

    i1

    Oak Ridge National Laboratory

    1
    Mallory Ladd gathers field samples on the coastal plain of northern Alaska. Photo courtesy, Mallory Ladd.

    2
    Mallory Ladd is a Bredesen Center student working with the NGEE-Arctic program at ORNL, seeking a better understanding of how soil water chemistry affects the aboveground environment. Photo courtesy, Jason Richards

    January 2, 2018

    Stephanie G. Seay, Communications
    seaysg@ornl.gov
    865.576.9894

    Mallory Ladd began trekking to the Arctic, even before her time at the Department of Energy’s Oak Ridge National Laboratory, in search of a better understanding of what’s going on belowground and how it links to changes in the larger landscape.

    The University of Tennessee, Knoxville (UTK) Bredesen Center student last year finished her third trip to Alaska to collect field data for the Next Generation Ecosystem Experiments-Arctic (NGEE-Arctic) program, supported by the U.S. Department of Energy’s Office of Biological and Environmental Research. The program harnesses the expertise of more than 140 scientists from national labs and universities studying how permafrost thaw may affect regional and global climate systems.

    Ladd is using her capabilities in analytical chemistry and mass spectrometry to examine how soil water chemistry is changing in the Arctic because of warming and thawing conditions, in order to better inform earth science models. She has been exploring those changes since her undergraduate days researching Arctic soil nitrogen at the University of Toledo.

    “Chemists usually spend a lot of time in the lab,” Ladd said. “But with this type of research I’m encouraged to get out and collect samples in the field. I feel closer to the science questions that way; working from sample collection to data analysis, from start to finish, has been enlightening.”

    Her path to the Arctic began at Toledo as the result of a chance encounter with Professor Mike Weintraub, who had just received funding from the National Science Foundation (NSF) to examine seasonality in the Arctic. Ladd was a senior at the university at the time, watching a screening of the documentary Dirt! with a friend. “We were talking about how interesting the movie was, how important the nutrient profile and soil chemistry are to so many things, when Mike joined in the conversation and told us he was looking for a lab technician with a chemistry background to join his team,” said Ladd. She worked with Weintraub for two years, visiting the Arctic twice for sampling as she studied soil nitrogen availability and impacts on plant life.

    Advancing science with cutting-edge instruments

    The work greatly influenced where Ladd would go for her doctoral studies. She was attracted to the Bredesen Center for Interdisciplinary Research & Graduate Education for its close ties to the national lab and the NGEE-Arctic program led by ORNL Environmental Sciences Division Director Stan Wullschleger—as well as by the offer of a personalized Ph.D. program that allows her to pursue science and a parallel track in policy. She began her time with ORNL and UTK in 2013, and is currently pursuing a doctorate in energy science and engineering. She is also an NSF Graduate Research Fellow.

    Wullschleger and UTK adviser Robert Hettich, a scientist in the Mass Spectrometry/Laser Spectroscopy Group at ORNL, helped Ladd design a program around Arctic metabolomics. In this focus area, she studies small molecules in the soil—how they are transported and break down over time, and how soil chemistry changes as temperatures rise.

    “Much of the success with this research is owed to being at ORNL with all the cutting-edge technologies it offers. The mass spectrometry resources here have been integral to getting high-resolution measurements in a short amount of time,” Ladd said.

    Her work for NGEE-Arctic started out in Barrow, Alaska, a coastal plain environment that has interesting microtopography where the soil physically moves as it freezes and thaws, creating rifts and valleys in the landscape. This summer, NGEE-Arctic conducted sampling in Nome, a sub-Arctic region that has undergone more warming and has markedly different, abundant plant life compared with Barrow.

    “My work at ORNL has allowed me to connect my fundamental scientific questions with DOE deliverables,” Mallory said. “It’s a great time to advocate for science, and to make sure we have strong, motivated young scientists doing excellent work.”

    Supporting the next generation of scientists

    Ladd has been very active in supporting her peers. She maintains a blog, “Think Like a Postdoc,” that chronicles her work and dispenses advice to other students.

    She also founded a student group at UTK called Pipeline: Vols for Women in STEM. A part of the university’s Commission for Women, the group works to enhance the status and representation of women in the 50-plus science, technology, engineering, and math fields at UTK through events such as an annual research symposium, interdisciplinary mentoring, monthly lectures, community outreach, and professional and social networking events.

    “The name ‘Pipeline’ refers to the analogy often used to describe the phenomenon that young girls and women are shown to be just as interested and scoring just as high as boys and men in STEM areas in K-12 and as college undergrads. But after graduating we see a divergence in the gender balance where men start to dominate these fields, often referred to as the leaky pipeline,” she said. Research in the past decade has discarded the notion that those changes happen because women start having children or are not “cut out” for long hours, she added.

    “Instead, studies are showing that the culprit is unconscious, or implicit, biases at the systemic level that are discouraging women from pursuing these careers as compared to their white male counterparts. The numbers are even worse for women of color, and especially at the leadership level,” she said. The Pipeline group tracks statistics on gender distribution in STEM areas at the university and aims to reverse that trend.

    Ladd’s curiosity and questioning nature began early. “I always questioned everything, and my parents were a huge part of that. They always encouraged me to not be afraid of standing out and to challenge the status quo. Science has been an outlet for that tendency,” she said. “I like the phrase that science turns ‘I don’t know’ into ‘I don’t know yet.’”

    Ladd grew up playing volleyball, with siblings who played rugby and soccer—meaning a lot of time on the road with various teams. “Our parents always told us it was okay to play in the dirt,” she said. Today away from the lab, she continues to spend time outdoors, kayaking, biking, and rock climbing, adding, “I’m a huge advocate for grad students making time for outside interests.”

    See the full article here .

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 3:35 pm on December 28, 2017 Permalink | Reply
    Tags: Femtosecond X-ray lasers, Inelastic X-ray scattering, , , ORNL, , , ,   

    From Optics & Photonics: “X-Ray Studies Probe Water’s Elusive Properties” 

    Optics & Photonics

    28 December 2017
    Stewart Wills

    1
    Unlike most substances, liquid water is denser than its solid phase, ice. [Image: Stockholm University]

    In two different X-ray investigations, researchers have dug into some of the exotic properties of that most familiar of substances—water.

    In one study, researchers from Sweden, Japan and South Korea used a femtosecond X-ray laser to investigate the behavior of evaporatively supercooled liquid water, and to confirm the long-suspected view that water at low temperatures can exist in two different liquid phases (Science). In the other, a U.S.-Japanese team used high-resolution inelastic X-ray scattering to probe the dynamics of water molecules and how the liquid’s hydrogen bonds contribute to its unusual characteristics (Science Advances).

    Burst pipes and floating cubes

    Anyone who has confronted a burst water pipe on a frozen winter morning has firsthand knowledge of one of H20’s unusual characteristics. Whereas most substances increase in density as they go from a liquid to a solid state, water reaches its maximum density at 4°C, above its nominal freezing point of 0°C. That’s also the reason that the ice cubes float at the top of your water glass rather than sinking to the bottom.

    Grappling with this anomalous behavior, a research team at Boston University suggested around 25 years ago, based on computer simulations, that in a metastable, supercooled state, water might actually coexist in two liquid phases—a low-density liquid and a high-density liquid. Those two phases, the researchers proposed, merged into a single phase at a critical point in water phase diagram at around –44°C (analogous to the better-known critical point at a higher temperature between water’s liquid and gas phases).

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    Experiments using femtosecond X-ray free-electron lasers illuminated fluctuations between two different phases of liquid water—a high-density liquid (red) and a low-density liquid (blue)—as a function of temperature in the supercooled regime. [Image: Stockholm University]

    Actually getting liquid water to that frigid point has, however, seemed a bit of a pipe dream. While very pure liquid water can be rapidly supercooled to temperatures moderately below 0°C relatively easily, the proposed critical point lies far below that temperature range, in what researchers have dubbed a “no-man’s land” in which ice crystalizes much faster than the timescale of conventional lab measurements.

    Leveraging ultrafast lasers

    To move past that barrier, a research team led by Anders Nilsson of Stockholm University, Sweden, turned to the rapid timescales enabled by femtosecond X-ray free-electron lasers (XFELs). At XFEL facilities in Korea and Japan [un-named], the team sent a stream of tiny water droplets (approximately 14 microns in diameter) into a vacuum chamber, and fired the XFEL at the droplets at varying distances from the water-dispensing nozzle to obtain ultrafast X-ray scattering data.

    The tiny size of the droplets meant that as they traveled through the vacuum they rapidly evaporatively cooled—with the amount of cooling related to the time they spent in vacuum under a well-established formula. Thus, by taking X-ray measurements at varying distances from the nozzle, the researchers could examine the structural behavior of the liquid water at multiple temperatures in the deep-supercooling regime, near the hypothesized critical point. “We were able to X-ray unimaginably fast before the ice froze,” Nilsson said in a press release, “and could observe how it fluctuated” between the two hypothesized metastable phases of liquid water.

    The experiments allowed the team to flesh out the phase diagram of liquid water in a supercooled region previously thought to be inaccessible to experiment. And the researchers believe that the use of femtosecond XFELs to probe thermodynamic functions and structural changes at extreme states “can be generalized to many supercooled liquids.”

    Illuminating water’s dynamics

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    A team led by scientists at the U.S. Oak Ridge National Laboratory used inelastic X-ray scattering to visualize and quantify the movement of water molecules in space and time. [Image: Jason Richards/Oak Ridge National Laboratory, US Dept. of Energy]

    A second set of experiments, from researchers at the U.S. Oak Ridge National Laboratory, the University of Tennessee, and the SPring-8 synchrotron laboratory in Japan, looked at water’s dynamics at room temperature, using inelastic X-ray scattering (IXS).

    SPring-8 synchrotron, located in Hyōgo Prefecture, Japan

    The researchers illuminated these dynamics through a series of experiments in which they trained radiation from the SPring-8 facility’s high-resolution IXS beamline, BL35XU, onto a 2-mm-thick sample of liquid water. Through multiple scattering measurements across a range of momentum and energy-transfer values, the team was able to build a detailed picture of the so-called Van Hove function, which describes the probability of interactions between a molecule and its nearest neighbors as a function of distance and time.

    The team found that water’s hydrogen bonds behave in a highly correlated fashion with respect to one another, which gives liquid water its high stability and explains its viscosity characteristics. And, in a press release, the researchers further speculated that the techniques used here could be extended to studying the dynamics and viscosity of a variety of other liquids. Some of those studies, they suggested, could prove useful in “the development of new types of semiconductor devices with liquid electrolyte insulating layers, better batteries and improved lubricants.”

    Here, the research team was interested in sussing out how water molecules interact in real time, and how the strongly directional hydrogen bonds of water molecules work together to determine properties such the liquid’s viscosity.

    See the full article here .

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    Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics. We welcome your submissions.

     
  • richardmitnick 4:48 pm on November 28, 2017 Permalink | Reply
    Tags: Cleaning automotive exhaust, , ORNL, SSZ-13 and ZSM-5 catalysts, Zeolite (hydrous silicate) catalytic converters   

    From ORNL: “Researchers compare ‘new’ and ‘aged’ catalytic converter at the nanoscale level” 

    i1

    Oak Ridge National Laboratory

    November 28, 2017
    Dawn Levy, Communications
    levyd@ornl.gov
    865.576.6448

    1
    Scientists peer inside materials used to clean automotive exhaust to understand why one works better than the other. Red and blue dots represent positions of copper and aluminum atoms, respectively, for two zeolite catalysts (SSZ-13 and ZSM-5) used in a diesel catalytic converter for a new car (fresh catalyst) and a car that has driven 135,000 miles (aged catalyst). After long use, SSZ-13 cleans exhaust better than ZSM-5. These atom-by-atom images reveal that this result is due to greater aggregation of copper and aluminum in ZSM-5. Image credit: Oak Ridge National Laboratory, U.S. Dept. of Energy

    Diesel vehicles today emit far fewer pollutants than older vehicles, thanks to a zeolite (hydrous silicate) catalytic converter that was invented around 10 years ago to reduce pollutants that cause the formation of acid rain and smog. Although many groups have investigated this catalyst, it remains unclear why a specific zeolite catalyst is much more effective than previous catalysts.

    By managing to “see inside” the zeolite particles in three dimensions at the nanoscale, researchers from Utrecht University in the Netherlands and the Department of Energy’s Oak Ridge National Laboratory have been able to directly image phenomena responsible for their enhanced stability and durability.

    After simulating 135,000 miles of engine use, they compared a ‘new’ and an ‘aged’ version of the zeolite catalyst, which revealed that this catalyst retains much more of its original structure than other diesel catalyst formulations. The researchers also found the underlying reasons this zeolite catalyst is so much more stable over its lifespan and experiences only minimal damage. The results are published in Nature Communications.

    Diesel catalytic converters are exposed to frequent temperature changes, extremely hot steam and pollutants, but they must remain stable for the entire life of the vehicle. The observed stability of this particular catalyst is due in part to its complexity.

    “At first glance, zeolites may seem easy to understand, but the more you study them, the more fascinated you become by their complexity,” said Joel Schmidt of Utrecht University, lead author of the publication. “In this material, it is becoming more and more evident that the way its structure isolates the active reaction site is key to its stability, and advanced characterization methods that can help us understand the active catalyst site environment are vital to knowing the subtle, but important details of materials utilized in zeolite catalytic converters.”

    Schmidt and his colleagues from Utrecht University connected with Jonathan Poplawsky at the Center for Nanophase Materials Sciences (CNMS), a DOE Office of Science User Facility at ORNL, to analyze the three-dimensional elemental distribution within the zeolite catalyst using a unique and powerful tool called local electrode atom probe tomography. With this technique, they could visualize all of the catalysts’ relevant chemical elements with three-dimensional resolution close to the atomic scale, for the as-produced “new” catalyst and after a 135,000-mile simulated aging procedure.

    The researchers found that after aging, the zeolite catalyst exhibits enhanced stability compared with other diesel-vehicle catalysts due primarily to structural and chemical properties that prevent the formation of a deactivating copper-aluminum-oxide phase. Thus, the optimal nanoscale distribution of elements within the zeolite structure—which enables optimal cleaning of combustion byproducts—remains intact during aging.

    “With this unique approach, we were able to add another piece to the puzzle of how to design catalysts that perform just as well at the end of a vehicle’s life as they did the day they rolled out of the factory,” said Bert Weckhuysen, Utrecht professor and co-author of the publication. “Since zeolite catalysts are used broadly in the chemical industry as well, insight on the migration of chemical elements under catalytic operating conditions is a very relevant contribution to realize more sustainable processes.”

    This work is supported by the NWO Gravitation program, Netherlands Center for Multiscale Catalytic Energy Conversion, and the European Research Council. The atom probe tomography measurements were conducted at CNMS.

    See the full article here .

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  • richardmitnick 8:24 pm on October 13, 2017 Permalink | Reply
    Tags: A new ultrafast optical technique for thermal measurements—time-domain thermoreflectance, , Chengyun Hua, , ORNL, ,   

    From ORNL: Women in STEM – “Laser-Focused: Chengyun Hua turns the heat up on materials research” 

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    Oak Ridge National Laboratory

    October 13, 2017
    Bill Cabage
    cabagewh@ornl.gov
    865.574.4399

    1
    Chengyun Hua applied for a Liane B. Russell Distinguished Early Career Fellowship after meeting ORNL researchers at a Society of Women Engineers conference.

    In Chengyun Hua’s research, everything revolves around heat and how it moves. As a Russell Fellow at the Department of Energy’s Oak Ridge National Laboratory, Hua carefully analyzes nanoscale heat transfer mechanisms using laser spectroscopy.

    “Heat is being generated from everywhere and we can collect that heat and convert it to energy,” she explained. “We essentially have enough heat being produced 24/7 through electronics and other sources that we could potentially impact the world’s energy production and ease today’s energy concerns.”

    Although heat has the potential to generate enough energy to power the universe, if not channeled properly, it can also become problematic.

    “We’ve seen recent news of cell phones bursting into flames,” Hua said. “The reason is too much heat is produced locally, and it has nowhere to go in a short period of time. The challenge is to capture that heat flow at the nanoscale and understand how we can more effectively dissipate it.”

    Through Hua’s work in ORNL’s Building Equipment Research group, a new ultrafast optical technique for thermal measurements—time-domain thermoreflectance—was deployed at ORNL for the first time. The technique measures the thermal properties of materials, including thermal conductivity. Using ORNL’s Ultrafast Laser Spectroscopy Laboratory, Hua measures material conductivity down to the nanometer.

    “When a material is heated using a pulsed laser, thermal stress is induced,” she explained. “The objective of raising the temperature of a material is to unveil the microscopic processes of the phonons [a type of elementary particle that plays an important role in many of the physical properties of solids, such as the thermal conductivity and the electrical conductivity] that govern the heat transport in solids. Ultimately, with this better understanding, we can design the next generation of materials—materials that not only withstand heat but also manage the heat and convert it into energy.”

    For the love of physics

    Hua grew up a world away in Shanghai, China. An only child of accountant parents, she excelled in mathematics and science, something that was not unusual in her home country.

    “It’s easy to get a job in the engineering discipline in China; it’s a highly respected profession,” she said. For Hua, however, getting accepted to study engineering physics at the University of Michigan, Ann Arbor, was an opportunity not to be missed.

    “Studying in Michigan was the first time I had ever been to the United States,” she said. “But it wasn’t until I entered the mechanical engineering program at Cal Tech that I truly felt at home.”

    Hua completed her PhD in mechanical engineering at the California Institute of Technology at Pasadena. There she met an advisor and professor who helped steer her current career path, challenging her to continue focusing on nanoscale heat transfer properties. “Cal Tech was a unique playground if you love mathematics and physics,” she said.

    After meeting some ORNL researchers at a Society of Women Engineers conference, Hua made the decision in early 2016 to apply for a fellowship that would allow her to focus on micro- and nanoscale heat transfer and energy conversion at the lab. The Liane B. Russell Distinguished Early Career Fellowship attracts scientists who have demonstrated outstanding scientific ability and research interests that align with core capabilities at the lab.

    “My advisor encouraged me to apply and within one week I wrote my proposal on ‘Exploring Thermal Transport in Nanostructured Materials for Thermal Energy Conversion and Management.’ I interviewed in November 2015 and four days after the new year, I was invited to become a fellow at ORNL,” she said.

    Uprooting again to East Tennessee, Hua has found a supportive community that encourages the sharing of new ideas and interdisciplinary research.

    “I’ve been able to live in different parts of the U.S.,” she said. “But, everywhere I’ve been, I’ve found support and an environment that promotes ideas and stimulating conversation between scientists.”

    While Hua has adapted to many moves and changes, one part of her research and studies remains unchanged.

    “Heat always flows from hot to cold,” she said. “It’s the constant in the continuum.”

    See the full article here .

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  • richardmitnick 9:32 am on July 7, 2017 Permalink | Reply
    Tags: , , , ORNL, St. Jude Children’s Research Hospital   

    From ORNL: “ORNL researchers apply imaging, computational expertise to St. Jude research” 

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    Oak Ridge National Laboratory

    July 6, 2017
    Stephanie G. Seay
    seaysg@ornl.gov
    865.576.9894

    1
    Left to right: ORNL’s Derek Rose, Matthew Eicholtz, Philip Bingham, Ryan Kerekes, and Shaun Gleason.

    2
    Measuring migrating neurons in a developing mouse brain.

    3
    Identifying and analyzing neurons in a mouse auditory cortex.
    No image credits for above images

    In the quest to better understand and cure childhood diseases, scientists at St. Jude Children’s Research Hospital accumulate enormous amounts of data from powerful video microscopes. To help St. Jude scientists mine that trove of data, researchers at Oak Ridge National Laboratory have created custom algorithms that can provide a deeper understanding of the images and quicken the pace of research.

    The work resides in St. Jude’s Department of Developmental Neurobiology in Memphis, Tennessee, where scientists use advanced microscopy to capture the details of phenomena such as nerve cell growth and migration in the brains of mice. ORNL researchers take those videos and leverage their expertise in image processing, computational science, and machine learning to analyze the footage and create statistics.

    A recent Science article details St. Jude research on brain plasticity, or the ability of the brain to change and form new connections between neurons. In this work, ORNL helped track mice brain cell electrical activity in the auditory cortex when the animals were exposed to certain tones.

    ORNL researchers created an algorithm to measure electrical activations, or signals, across groups of neurons, collecting statistics and making correlations between cell activity in the auditory cortex and tones heard by the mice. The team first had to stabilize the video because it was taken while the mice were awake and moving to ensure a proper analysis was being conducted, said Derek Rose, who now leads the work at ORNL.

    See the full article here .

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 3:37 pm on July 5, 2017 Permalink | Reply
    Tags: A condensed matter cousin of the Higgs boson, Condensed matter researchers have recently uncovered new quantum states known as quasiparticles including the Higgs mode, Higgs amplitude mode, Neutron scattering techniques, ORNL   

    From ORNL: “Neutrons detect elusive Higgs amplitude mode in quantum material” 

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    Oak Ridge National Laboratory

    July 5, 2017
    Sara Shoemaker
    shoemakerms@ornl.gov
    865.576.9219

    1
    ORNL’s Tao Hong analyzed a copper bromide compound’s low-energy behavior during a neutron scattering experiment at the lab’s High Flux Isotope Reactor that yielded the elusive Higgs amplitude mode in two dimensions with no decay.

    ORNL High Flux Isotope Reactor

    2
    The ORNL-led research team selected a crystal composed of copper bromide – because the copper ion is ideal for studying exotic quantum effects – to observe the elusive Higgs amplitude mode in two dimensions. The sample was examined using cold neutron triple-axis spectrometer beams for neutron scattering at the High Flux Isotope Reactor.

    3
    During the neutron scattering experiment, the sample containing copper ions exhibited exotic quantum properties as certain quasiparticles spin in a wave-like configuration, eventually revealing the Higgs amplitude mode.

    A team led by the Department of Energy’s Oak Ridge National Laboratory has used sophisticated neutron scattering techniques to detect an elusive quantum state known as the Higgs amplitude mode in a two-dimensional material.

    The Higgs amplitude mode is a condensed matter cousin of the Higgs boson, the storied quantum particle theorized in the 1960s and proven experimentally in 2012. It is one of a number of quirky, collective modes of matter found in materials at the quantum level. By studying these modes, condensed matter researchers have recently uncovered new quantum states known as quasiparticles, including the Higgs mode.

    These studies provide unique opportunities to explore quantum physics and apply its exotic effects in advanced technologies such as spin-based electronics, or spintronics, and quantum computing.

    “To excite a material’s quantum quasiparticles in a way that allows us to observe the Higgs amplitude mode is quite challenging,” said Tao Hong, an instrument scientist with ORNL’s Quantum Condensed Matter Division.

    Although the Higgs amplitude mode has been observed in various systems, “the Higgs mode would often become unstable and decay, shortening the opportunity to characterize it before losing sight of it,” Hong said.

    The ORNL-led team offered an alternative method. The researchers selected a crystal composed of copper bromide, because the copper ion is ideal for studying exotic quantum effects, Hong explained. They began the delicate task of “freezing” the material’s agitating quantum-level particles by lowering its temperature to 1.4 Kelvin, which is about minus 457.15 degrees Fahrenheit.

    The researchers fine-tuned the experiment until the particles reached the phase located near the desired quantum critical point—the sweet spot where collective quantum effects spread across wide distances in the material, which creates the best conditions to observe a Higgs amplitude mode without decay.

    With neutron scattering performed at ORNL’s High Flux Isotope Reactor, the research team observed the Higgs mode with an infinite lifetime: no decay.

    “There’s an ongoing debate in physics about the stability of these very delicate Higgs modes,” said Alan Tennant, chief scientist of ORNL’s Neutron Sciences Directorate. “This experiment is really hard to do, especially in a two-dimensional system. And, yet, here’s a clear observation, and it’s stabilized.”

    The research team’s observation provides new insights into the fundamental theories underlying exotic materials including superconductors, charge-density wave systems, ultracold bosonic systems and antiferromagnets.

    “These breakthroughs are having widespread impact on our understanding of materials’ behavior at the atomic scale,” Hong added.

    The study, titled, Direct observation of the Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point, was published in Nature Physics. It was co-authored by ORNL’s Tao Hong, Sachith E. Dissanayake, Harish Agrawal and David A. (Alan) Tennant, and scientists from Shizuoka University, the National Institute of Standards and Technology [NIST], University of Maryland, University of Jordan, Clark University, Helmholtz-Zentrum Berlin for Materials and Energy and Lehrstuhl für Theoretische Physik I.

    The team used cold neutron triple-axis spectrometer beams for studying exotic magnetic effects and analyzed low-energy excitations in the copper bromide compound. The unpolarized neutron scattering measurements were performed at ORNL’s HFIR and at Helmholtz-Zentrum Berlin for Materials and Energy. For contrasting data from polarized neutron-scattering measurements, they also employed a high-intensity multi-axis crystal spectrometer at NIST’s Center for Neutron Research.

    The work performed at ORNL’s HFIR, a DOE Office of Science User Facility, and was funded by the DOE Office of Science.

    See the full article here .

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  • richardmitnick 3:19 pm on June 28, 2017 Permalink | Reply
    Tags: , IMAGINE neutron scattering diffractometer, LPMOs - lytic polysaccharide monooxygenases, , North Carolina State University, ORNL, ORNL’s High Flux Isotope Reactor   

    From ORNL: “‘On your mark, get set'” 

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    Oak Ridge National Laboratory

    June 27, 2017
    Jeremy Rumsey
    rumseyjp@ornl.gov
    865.576.2038

    1
    A combination of X-ray and neutron scattering has revealed new insights into how a highly efficient industrial enzyme is used to break down cellulose. Knowing how oxygen molecules (red) bind to catalytic elements (illustrated by a single copper ion) will guide researchers in developing more efficient, cost-effective biofuel production methods. (Image credit: ORNL/Jill Hemman)

    Producing biofuels like ethanol from plant materials requires various enzymes to break down the cellulosic fibers. Scientists using neutron scattering have identified the specifics of an enzyme-catalyzed reaction that could significantly reduce the total amount of enzymes used, improving production processes and lowering costs.

    Researchers from the Department of Energy’s Oak Ridge National Laboratory and North Carolina State University used a combination of X-ray and neutron crystallography to determine the detailed atomic structure of a specialized fungal enzyme.

    A deeper understanding of the enzyme reactivity could also lead to improved computational models that will further guide industrial applications for cleaner forms of energy. Their results are published in the journal Angewandte Chemie International Edition.

    Part of a larger family known as lytic polysaccharide monooxygenases, or LPMOs, these oxygen-dependent enzymes act in tandem with hydrolytic enzymes—which chemically break down large complex molecules with water—by oxidizing and breaking the bonds that hold cellulose chains together. The combined enzymes can digest biomass more quickly than currently used enzymes and speed up the biofuel production process.

    “These enzymes are already used in industrial applications, but they’re not well understood,” said lead author Brad O’Dell, a graduate student from NC State working in the Biology and Soft Matter Division of ORNL’s Neutron Sciences Directorate. “Understanding each step in the LPMO mechanism of action will help industry use these enzymes to their full potential and, as a result, make final products cheaper.”

    In an LPMO enzyme, oxygen and cellulose arrange themselves through a sequence of steps before the biomass deconstruction reaction occurs. Sort of like “on your mark, get set, go,” says O’Dell.

    To better understand the enzyme’s reaction mechanism, O’Dell and coauthor Flora Meilleur, ORNL instrument scientist and an associate professor at NC State, used the IMAGINE neutron scattering diffractometer at ORNL’s High Flux Isotope Reactor to see how the enzyme and oxygen molecules were behaving in the steps leading up to the reaction—from the “resting state” to the “active state.”

    ORNL IMAGINE neutron scattering diffractometer

    The resting state, O’Dell says, is where all the critical components of the enzyme assemble to bind oxygen and carbohydrate. When electrons are delivered to the enzyme, the system moves from the resting state to the active state—i.e., from “on your mark” to “get set.”

    In the active state, oxygen binds to a copper ion that initiates the reaction. Aided by X-ray and neutron diffraction, O’Dell and Meilleur identified a previously unseen oxygen molecule being stabilized by an amino acid, histidine 157.

    Hydrogen is a key element of amino acids like histidine 157. Because neutrons are particularly sensitive to hydrogen atoms, the team was able to determine that histidine 157 plays a significant role in transporting oxygen molecules to the copper ion in the active site, revealing a vital detail about the first step of the LPMO catalytic reaction.

    “Because neutrons allow us to see hydrogen atoms inside the enzyme, we gained essential information in deciphering the protein chemistry. Without that data, the role of histidine 157 would have remained unclear,” Meilleur said. “Neutrons were instrumental in determining how histidine 157 stabilizes oxygen to initiate the first step of the LPMO reaction mechanism.”

    Their results were subsequently confirmed via quantum chemical calculations performed by coauthor Pratul Agarwal from ORNL’s Computing and Computational Sciences Directorate.

    Research material preparation was supported by the ORNL Center for Structural Molecular Biology. X-ray data were collected at the Argonne National Laboratory Advanced Photon Source through access provided by the Southeast Regional Collaborative Access Team.

    O’Dell says their results refine the current understanding of LPMOs for science and industry researchers.

    “This is a big step forward in unraveling how LPMO’s initiate the breakdown of carbohydrates,” O’Dell said. “Now we need to characterize the enzyme’s activated state when the protein is also bound to a carbohydrate that mimics cellulose. Then we’ll have the chance to see what structural changes happen when the starting pistol is fired and the reaction takes off.”

    HFIR is a DOE Office of Science User Facility. UT-Battelle manages ORNL for the Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.

    See the full article here .

    Please help promote STEM in your local schools.

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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