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  • richardmitnick 12:21 pm on June 15, 2018 Permalink | Reply
    Tags: , , Retinal, SLAC Labs   

    From SLAC Lab: “Scientists Make the First Molecular Movie of One of Nature’s Most Widely Used Light Sensors” 


    From SLAC Lab

    June 14, 2018
    Glennda Chui


    A molecular movie based on experimental data shows the retinal molecule, in green, changing shape along with parts of its surrounding protein pocket, in pink, when hit by light. The changing numbers are distances in angstroms. One angstrom is one ten-billionth of a meter. That’s roughly the diameter of the smallest atoms. (Paul Scherrer Institute, Andy Freeberg/SLAC)

    The X-ray laser movie shows what happens when light hits retinal, a key part of vision in animals and photosynthesis in microbes. The action takes place in a trillionth of an eye blink.

    Scientists have made the first molecular movie of the instant when light hits a sensor that’s widely used in nature for probing the environment and harvesting energy from light. The sensor, a form of vitamin A known as retinal, is central to a number of important light-driven processes in people, animals, microbes and algae, including human vision and some forms of photosynthesis, and the movie shows it changing shape in a trillionth of an eye blink.

    “To my knowledge, nobody has measured changes in a retinal biosensor so quickly and so accurately,” said Jörg Standfuss, a biologist at the Paul Scherrer Institute (PSI) in Switzerland who led the research at the Department of Energy’s SLAC National Accelerator Laboratory. “And the fact that we saw just the opposite of what we intuitively expected was spectacular and surprising to us.”

    The team carried out their experiments at the lab’s Linac Coherent Light Source (LCLS) X-ray laser and reported the results today in Science.

    SLAC/LCLS

    Comming soon (A really bad attempt at lab humor. In fact, it will be a while).

    SLAC/LCLS II projected view

    In the past, scientists had to fill the gaps in their knowledge about retinal’s behavior by making inferences based on theory and computer simulations, said Mark Hunter, a staff scientist at LCLS and paper co-author. But in this study, “LCLS’s super-short pulses allowed us to collect data on where the atoms actually were in space and how that changed over time,” he said, “so it gave us a much more direct visualization of molecules in motion.”

    Colorful Lakes and Arching Cats

    Retinal is so central to human vision – it’s named for the retina at the back of the eye – that scientists have been studying it for nearly a century, steadily building a more detailed picture of how it works. It’s also used in the burgeoning field of optogenetics to turn groups of nerve cells on and off, revealing how the brain works and how things go wrong in conditions like depression, stroke and addiction.

    The retinal studied in this experiment came from salt-loving microbes that use it to harvest energy from the sun. (Fun fact: Purple and orange-red pigments in these microbes give the briny waters they live in, from San Francisco Bay salt ponds to Senegal’s Lake Retba, their incredibly vivid colors.)

    Retinal does its job while snuggled deep into a pocket of specialized proteins in the membrane of the cell. When hit by light, the retinal changes shape – in this case it curves, like a cat arching its back. This creates a signal that’s transmitted by the protein into the cell’s interior, initiating photosynthesis or vision.

    Scientists thought retinal set off the signal by pushing on the protein pocket as it changed shape. But the LCLS experiments found just the opposite: The pocket actually changed shape first, creating space for the retinal to perform its arching-cat maneuver. Nearby water molecules also moved aside and made room, Standfuss said. It all took place within 200 to 500 femtoseconds, or millionths of a billionth of a second. That’s about a trillionth of the blink of an eye, making this one of the fastest chemical reactions known in living things.

    “In retrospect, this makes a lot of sense,” Standfuss said. “We always say seeing is believing in structural biology, and in this case it’s very true. The molecular movie we made makes it so obvious what’s going on that you can immediately grasp it. This solves a very important piece of the puzzle of how retinal works that people have been wondering about.”

    The protein pocket’s initial movements are triggered by small changes in electrical charge that rearrange certain chemical bonds, he said. These movements guide the retinal’s response and make it much more efficient, which is why it requires only a few photons of light and why nature can use that light so effectively.


    In this pair of molecular movies we see the retinal molecule (in the middle of each frame) and parts of its surrounding protein pocket with their shapes defined by their electron clouds (blue lines). The top frame shows the retinal molecule from the side, and the bottom one shows it from the top as it curves in response to light. (Paul Scherrer Institute)

    Catching Molecules in Action

    How can you watch something so small that happens so fast? The X-ray laser was key, Standfuss said. LCLS produces brilliant pulses of X-ray laser light that scatter off the electrons in a sample and reveal how its atoms are arranged. Like a camera with an extreme zoom lens and ultrafast shutter speed, the X-ray laser can also make snapshots of molecules moving, breaking apart and interacting with each other.

    In this case, the researchers looked at samples of retinal snuggled into pockets of bacteriorhodopsin, a purple protein found in simple microbes like those in the salt ponds.

    After years of effort, PSI postdoctoral researcher Przemyslaw Nogly, the lead author of the report, found ways to pack these retinal-protein pairs into thousands and thousands of tiny but well-ordered crystals. One after another, crystals were hit with light from an optical laser – a stand-in for sunlight – followed by X-ray laser pulses to record the response. Then Nogly and the team boiled down data into 20 snapshots and assembled them into stop-action movies that show the retinal moving in sync with its protein pocket.

    Proteins like bacteriorhodopsin that sit in cell membranes are notoriously difficult to study because it’s so hard to form them into crystals for X-ray experiments, Hunter said. But scientists have learned that they crystallize more readily when embedded in a fatty, toothpaste-like sludge that mimics their natural environment, and that’s how these crystals were formed and delivered into the X-ray beam.

    The researchers were also able to detect “protein quakes,” vibrations that release some of the energy deposited by the light flashes. These had been predicted by theory and came off as expected.

    Standfuss said he has spent most of his career studying retinal and its role in vision, which involves slightly different shape changes in the protein-embedded molecule. “I really hope that we can now study the same reaction in many different systems,” he said. “Now that we see for the first time how it works in one particular bacterial protein, I want to understand how it works in the human eye as well.”

    LCLS researchers Sergio Carbajo, Jason Koglin, Matthew Seaberg and Thomas Lane were co-authors of this study. Other contributors came from PSI, the University of Gothenburg in Sweden, the Fritz Haber Center for Molecular Dynamics at the Hebrew University of Jerusalem, the RIKEN SPring-8 Center and Kyoto University in Japan, the Center for Free-Electron Laser Science at DESY in Germany and Arizona State University. Major funding came from the European Horizon 2020 Program, the Swedish Research Council and the Swiss National Science Foundation.

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 8:53 pm on May 15, 2018 Permalink | Reply
    Tags: Cryo-EM, , SLAC Labs   

    From SLAC Lab: “SLAC Will Open One of Three NIH National Service Centers for Cryo-Electron Microscopy” 


    From SLAC Lab

    May 15, 2018
    Glennda Chui

    1
    Proton pumps control the balance of acidity in the cell. This cryo-EM image shows a proton pump that’s part of an enzyme found in both yeast and humans. It consists of 15 protein subunits. The pink part rotates to transport protons across the cell’s outer membrane. Mutations in the human version of the pump interfere with the body’s normal cycle of continually replacing old bone with new. (https://www.cell.com/molecular-cell/abstract/S1097-2765%2818%2930104-7 [Molecular Cell])

    The National Institutes of Health center on the SLAC campus will make this revolutionary technology available to scientists nationwide and teach them how to use it to study 3D structures of biological machines and molecules.

    The National Institutes of Health announced today that it will establish a national service and training center for cryogenic electron microscopy research at the Department of Energy’s SLAC National Accelerator Laboratory.

    Professor Wah Chiu and members of the new Stanford-SLAC cryo-EM team stand in front of a cryo-EM instrument as work nears completion on their new facility at SLAC. (Dawn Harmer- SLAC)

    It’s one of three national service and training centers the NIH is setting up to make the Nobel prize-winning technology available to scientists nationwide and teach them how to use it.

    Known as cryo-EM for short, this powerful high-resolution imaging method has become a revolutionary tool for biology over the past few years due to rapid improvements in transmission electron microscopes, detectors and software. Last year the technique earned three of its key developers the 2017 Nobel Prize in chemistry. Cryo-EM allows scientists to make detailed 3D images of DNA, RNA, proteins, viruses, cells and the tiny molecular machines within the cell, revealing how they change shape and interact in complex ways while carrying out life’s functions.

    However, the high cost of buying and operating the high-voltage electron microscopes and a lack of training opportunities have slowed the widespread adoption of the technology.

    The new data collection centers will address this by providing funding for instruments and associated lab equipment and bringing in scientists from across the nation for research and training. In addition to SLAC, centers will be set up at the New York Structural Biology Center and at the Oregon Health & Science University in partnership with DOE’s Pacific Northwest National Laboratory, the NIH announced. The awards are anticipated to total $128 million over six years, pending the availability of funds.

    “Cryo-electron microscopy is allowing us to resolve the three-dimensional structures of important biomolecules involved in disease that were inaccessible using previous technologies,” said National Institute of General Medical Sciences Director Jon R. Lorsch. “NIH wants to ensure as many scientists as possible have access to this crucial technology.”

    The NIH center at SLAC will be known as the SLAC-Stanford Cryo-EM Center (S2C2). It marks the second major step in carrying out the Stanford-SLAC Cryo-EM Initiative, whose goal is to establish one of the world’s foremost hubs for cryo-EM research and training for scientists at the lab, the university and in the broader scientific community around the globe.

    The first step took place earlier this year, when the Stanford-SLAC Cryo-EM Facility opened on the SLAC campus with four state-of-the-art microscopes.

    The new NIH center, which will operate independently but in synergy with the recently established Stanford-SLAC facility, will install several more electron microscopes and associated specimen preparation devices in the lab’s soon-to-open Arrillaga Science Center.

    “This new center complements our existing facilities and capabilities, enhancing an integrated suite of unique tools to advance materials, chemical and biological science discoveries critical to the DOE Office of Science mission,” said SLAC Director Chi-Chang Kao.

    Wah Chiu, a professor at SLAC and Stanford and leader of the cryo-EM program, added, “This is an exciting moment for those in the U.S. scientific community who do not have access to cryo-EM instrumentation in their own institutions, and we are very pleased to share our decades of experience in this research with others.

    “I believe that this NIH initiative will have a great impact on popularizing this powerful imaging tool,” he said, “which will likely lead to many discoveries of 3D structures of biological machines and molecules in both their normal and diseased states and hasten our national efforts to prevent and cure a variety of diseases, including cancer, diabetics, neurodegeneration, cardiovascular diseases and infection.”

    For questions or comments, contact the SLAC Office of Communications at communications@slac.stanford.edu.

    See the full article here .

    Please help promote STEM in your local schools.

    stem

    Stem Education Coalition

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 9:01 am on May 7, 2018 Permalink | Reply
    Tags: , , Construction Begins on One of the World’s Most Sensitive Dark Matter Experiments, , , , SLAC Labs, , SuperCDMS SNOLAB experiment,   

    From SLAC Lab: “Construction Begins on One of the World’s Most Sensitive Dark Matter Experiments” 


    From SLAC Lab

    May 7, 2018

    Press Office Contact: Andrew Gordon,
    agordon@slac.stanford.edu
    (650) 926-2282

    Written by Manuel Gnida

    1
    The future SuperCDMS SNOLAB experiment will hunt for weakly interacting massive particles (WIMPs), hypothetical components of dark matter. If a WIMP (white trace) strikes an atom inside the experiment’s detector crystals (gray), it will cause the crystal lattice to vibrate (blue). The collision will also send electrons (red) through the crystal that enhance the vibrations. (Greg Stewart/SLAC National Accelerator Laboratory)

    2
    The future SuperCDMS SNOLAB experiment will hunt for weakly interacting massive particles (WIMPs), hypothetical components of dark matter. This photo shows one of the experiment’s detector crystals within its protective copper housing. (Andy Freeberg/SLAC National Accelerator Laboratory)

    3
    SLAC’s Paul Brink handles the SuperCDMS SNOLAB engineering tower. (Chris Smith/SLAC National Accelerator Laboratory)

    4
    A SuperCDMS SNOLAB detector, fabricated at Texas A&M University. (Matt Cherry/SuperCDMS collaboration/SLAC National Accelerator Laboratory)

    5
    Dan Bauer (left) and Mark Ruschman in Fermilab’s Lab G , where the SuperCDMS SNOLAB project is preparing to test the cryogenics system for the new experiment. (Reidar Hahn/Fermi National Accelerator Laboratory)

    6
    Fermilab’s Mark Ruschman tests prototypes for the SuperCDMS SNOLAB cryogenics system. (Reidar Hahn/Fermi National Accelerator Laboratory)

    The SuperCDMS SNOLAB project, a multi-institutional effort led by SLAC, is expanding the hunt for dark matter to particles with properties not accessible to any other experiment.

    SNOLAB, Sudbury, Ontario, Canada.

    The U.S. Department of Energy has approved funding and start of construction for the SuperCDMS SNOLAB experiment, which will begin operations in the early 2020s to hunt for hypothetical dark matter particles called weakly interacting massive particles, or WIMPs. The experiment will be at least 50 times more sensitive than its predecessor, exploring WIMP properties that can’t be probed by other experiments and giving researchers a powerful new tool to understand one of the biggest mysteries of modern physics.

    The DOE’s SLAC National Accelerator Laboratory is managing the construction project for the international SuperCDMS collaboration of 111 members from 26 institutions, which is preparing to do research with the experiment.

    “Understanding dark matter is one of the hottest research topics – at SLAC and around the world,” said JoAnne Hewett, head of SLAC’s Fundamental Physics Directorate and the lab’s chief research officer. “We’re excited to lead the project and work with our partners to build this next-generation dark matter experiment.”

    With the DOE approvals, known as Critical Decisions 2 and 3, the researchers can now build the experiment. The DOE Office of Science will contribute $19 million to the effort, joining forces with the National Science Foundation ($12 million) and the Canada Foundation for Innovation ($3 million).

    “Our experiment will be the world’s most sensitive for relatively light WIMPs – in a mass range from a fraction of the proton mass to about 10 proton masses,” said Richard Partridge, head of the SuperCDMS group at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of SLAC and Stanford University. “This unparalleled sensitivity will create exciting opportunities to explore new territory in dark matter research.”

    An Ultracold Search 6,800 Feet Underground

    Scientists know that visible matter in the universe accounts for only 15 percent of all matter. The rest is a mysterious substance, called dark matter. Due to its gravitational pull on regular matter, dark matter is a key driver for the evolution of the universe, affecting the formation of galaxies like our Milky Way. It therefore is fundamental to our very own existence.

    But scientists have yet to find out what dark matter is made of. They believe it could be composed of dark matter particles, and WIMPs are top contenders. If these particles exist, they would barely interact with their environment and fly right through regular matter untouched. However, every so often, they could collide with an atom of our visible world, and dark matter researchers are looking for these rare interactions.

    7
    The centerpiece of the SuperCDMS SNOLAB experiment will be four detector towers (left), each containing six detector packs. The towers will be mounted inside the SNOBOX (right), a vessel in which the detector packs will be cooled to almost absolute zero temperature. (Greg Stewart/SLAC National Accelerator Laboratory)

    In the SuperCDMS SNOLAB experiment, the search will be done using silicon and germanium crystals, in which the collisions would trigger tiny vibrations. However, to measure the atomic jiggles, the crystals need to be cooled to less than minus 459.6 degrees Fahrenheit – a fraction of a degree above absolute zero temperature. These ultracold conditions give the experiment its name: Cryogenic Dark Matter Search, or CDMS. The prefix “Super” indicates an increased sensitivity compared to previous versions of the experiment.

    The collisions would also produce pairs of electrons and electron deficiencies that move through the crystals, triggering additional atomic vibrations that amplify the signal from the dark matter collision. The experiment will be able to measure these “fingerprints” left by dark matter with sophisticated superconducting electronics.

    The experiment will be assembled and operated at the Canadian laboratory SNOLAB – 6,800 feet underground inside a nickel mine near the city of Sudbury. It’s the deepest underground laboratory in North America. There it will be protected from high-energy particles, called cosmic radiation, which can create unwanted background signals.

    8
    The SuperCDMS dark matter experiment will be located at the Canadian laboratory SNOLAB, 2 kilometers (6,800 feet) underground inside a nickel mine near the city of Sudbury. It’s the deepest underground laboratory in North America. There it will be protected from high-energy particles, called cosmic radiation, which can create unwanted background signals. (Greg Stewart/SLAC National Accelerator Laboratory; inset: SNOLAB)

    “SNOLAB is excited to welcome the SuperCDMS SNOLAB collaboration to the underground lab,” said Kerry Loken, SNOLAB project manager. “We look forward to a great partnership and to supporting this world-leading science.”

    Over the past months, a detector prototype has been successfully tested at SLAC. “These tests were an important demonstration that we’re able to build the actual detector with high enough energy resolution, as well as detector electronics with low enough noise to accomplish our research goals,” said KIPAC’s Paul Brink, who oversees the detector fabrication at Stanford.

    Together with seven other collaborating institutions, SLAC will provide the experiment’s centerpiece of four detector towers, each containing six crystals in the shape of oversized hockey pucks. The first tower could be sent to SNOLAB by the end of 2018.

    “The detector towers are the most technologically challenging part of the experiment, pushing the frontiers of our understanding of low-temperature devices and superconducting readout,” said Bernard Sadoulet, a collaborator from the University of California, Berkeley.

    A Strong Collaboration for Extraordinary Science

    In addition to SLAC, two other national labs are involved in the project. Fermi National Accelerator Laboratory is working on the experiment’s intricate shielding and cryogenics infrastructure, and Pacific Northwest National Laboratory is helping understand background signals in the experiment, a major challenge for the detection of faint WIMP signals.

    9
    Slideshow of SuperCDMS SNOLAB photos. For more images, visit the SuperCDMS SNOLAB photostream on Flickr.

    A number of U.S. and Canadian universities also play key roles in the experiment, working on tasks ranging from detector fabrication and testing to data analysis and simulation. The largest international contribution comes from Canada and includes the research infrastructure at SNOLAB.

    “We’re fortunate to have a close-knit network of strong collaboration partners, which is crucial for our success,” said KIPAC’s Blas Cabrera, who directed the project through the CD-2/3 approval milestone. “The same is true for the outstanding support we’re receiving from the funding agencies in the U.S. and Canada.”

    Fermilab’s Dan Bauer, spokesperson of the SuperCDMS collaboration said, “Together we’re now ready to build an experiment that will search for dark matter particles that interact with normal matter in an entirely new region.”

    SuperCDMS SNOLAB will be the latest in a series of increasingly sensitive dark matter experiments. The most recent version, located at the Soudan Mine in Minnesota, completed operations in 2015.

    “The project has incorporated lessons learned from previous CDMS experiments to significantly improve the experimental infrastructure and detector designs for the experiment,” said SLAC’s Ken Fouts, project manager for SuperCDMS SNOLAB. “The combination of design improvements, the deep location and the infrastructure support provided by SNOLAB will allow the experiment to reach its full potential in the search for low-mass dark matter.”

    For more information on the SuperCDMS SNOLAB project and the SuperCDMS collaboration, check out this website:

    SuperCDMS SNOLAB Website

    See the full article here .

    Please help promote STEM in your local schools.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 3:18 pm on April 14, 2018 Permalink | Reply
    Tags: , , , , SLAC Labs,   

    From SLAC: “Scientists Use Machine Learning to Speed Discovery of Metallic Glass” 


    SLAC Lab

    April 13, 2018
    Glennda Chui

    1
    Fang Ren, who developed algorithms to analyze data on the fly while a postdoctoral scholar at SLAC, at a Stanford Synchrotron Radiation Lightsource beamline where the system has been put to use. (Dawn Harmer/SLAC National Accelerator Laboratory)

    SLAC and its collaborators are transforming the way new materials are discovered. In a new report, they combine artificial intelligence and accelerated experiments to discover potential alternatives to steel in a fraction of the time.

    Blend two or three metals together and you get an alloy that usually looks and acts like a metal, with its atoms arranged in rigid geometric patterns.

    But once in a while, under just the right conditions, you get something entirely new: a futuristic alloy called metallic glass that’s amorphous, with its atoms arranged every which way, much like the atoms of the glass in a window. Its glassy nature makes it stronger and lighter than today’s best steel, plus it stands up better to corrosion and wear.

    Even though metallic glass shows a lot of promise as a protective coating and alternative to steel, only a few thousand of the millions of possible combinations of ingredients have been evaluated over the past 50 years, and only a handful developed to the point that they may become useful.

    Now a group led by scientists at the Department of Energy’s SLAC National Accelerator Laboratory, the National Institute of Standards and Technology (NIST) and Northwestern University has reported a shortcut for discovering and improving metallic glass – and, by extension, other elusive materials – at a fraction of the time and cost.

    The research group took advantage of a system at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) that combines machine learning – a form of artificial intelligence where computer algorithms glean knowledge from enormous amounts of data – with experiments that quickly make and screen hundreds of sample materials at a time.

    SLAC/SSRL

    This allowed the team to discover three new blends of ingredients that form metallic glass, and to do this 200 times faster than it could be done before, they reported today in Science Advances.

    2
    (Yvonne Tang/SLAC National Accelerator Laboratory)

    “It typically takes a decade or two to get a material from discovery to commercial use,” said Northwestern Professor Chris Wolverton, an early pioneer in using computation and AI to predict new materials and a co-author of the paper. “This is a big step in trying to squeeze that time down. You could start out with nothing more than a list of properties you want in a material and, using AI, quickly narrow the huge field of potential materials to a few good candidates.”

    The ultimate goal, he said, is to get to the point where a scientist could scan hundreds of sample materials, get almost immediate feedback from machine learning models and have another set of samples ready to test the next day – or even within the hour.

    Over the past half century, scientists have investigated about 6,000 combinations of ingredients that form metallic glass, added paper co-author Apurva Mehta, a staff scientist at SSRL: “We were able to make and screen 20,000 in a single year.”

    Just Getting Started

    While other groups have used machine learning to come up with predictions about where different kinds of metallic glass can be found, Mehta said, “The unique thing we have done is to rapidly verify our predictions with experimental measurements and then repeatedly cycle the results back into the next round of machine learning and experiments.”

    There’s plenty of room to make the process even speedier, he added, and eventually automate it to take people out of the loop altogether so scientists can concentrate on other aspects of their work that require human intuition and creativity. “This will have an impact not just on synchrotron users, but on the whole materials science and chemistry community,” Mehta said.

    The team said the method will be useful in all kinds of experiments, especially in searches for materials like metallic glass and catalysts whose performance is strongly influenced by the way they’re manufactured, and those where scientists don’t have theories to guide their search. With machine learning, no previous understanding is needed. The algorithms make connections and draw conclusions on their own, and this can steer research in unexpected directions.

    “One of the more exciting aspects of this is that we can make predictions so quickly and turn experiments around so rapidly that we can afford to investigate materials that don’t follow our normal rules of thumb about whether a material will form a glass or not,” said paper co-author Jason Hattrick-Simpers, a materials research engineer at NIST. “AI is going to shift the landscape of how materials science is done, and this is the first step.”

    Strength in Numbers

    The paper is the first scientific result associated with a DOE-funded pilot project where SLAC is working with a Silicon Valley AI company, Citrine Informatics, to transform the way new materials are discovered and make the tools for doing that available to scientists everywhere.

    Founded by former graduate students from Northwestern and Stanford University, Citrine has created a materials science data platform where data that had been locked away in published papers, spreadsheets and lab notebooks is stored in a consistent format so it can be analyzed with AI specifically designed for materials.

    “We want to take materials and chemical data and use them effectively to design new materials and optimize manufacturing,” said Greg Mulholland, founder and CEO of the company. “This is the power of artificial intelligence: As scientists generate more data, it learns alongside them, bringing hidden trends to the surface and allowing scientists to identify high-performance materials much faster and more effectively than relying on traditional, purely human-driven materials development.”

    Until recently, thinking up, making and assessing new materials was painfully slow. For instance, the authors of the metallic glass paper calculated that even if you could cook up and examine five potential types of metallic glass a day, every day of the year, it would take more than a thousand years to plow through every possible combination of metals. When they do discover a metallic glass, researchers struggle to overcome problems that hold these materials back. Some have toxic or expensive ingredients, and all of them share glass’s brittle, shatter-prone nature.

    Over the past decade, scientists at SSRL and elsewhere have developed ways to automate experiments so they can create and study more novel materials in less time. Today, some SSRL users can get a preliminary analysis of their data almost as soon as it comes out with AI software developed by SSRL in conjunction with Citrine and the CAMERA project at DOE’s Lawrence Berkeley National Laboratory.

    “With these automated systems we can analyze more than 2,000 samples per day,” said Fang Ren, the paper’s lead author, who developed algorithms to analyze data on the fly and coordinated their integration into the system while a postdoctoral scholar at SLAC.

    Experimenting with Data

    In the metallic glass study, the research team investigated thousands of alloys that each contain three cheap, nontoxic metals.

    They started with a trove of materials data dating back more than 50 years, including the results of 6,000 experiments that searched for metallic glass. The team combed through the data with advanced machine learning algorithms developed by Wolverton and graduate student Logan Ward at Northwestern.

    Based on what the algorithms learned in this first round, the scientists crafted two sets of sample alloys using two different methods, allowing them to test how manufacturing methods affect whether an alloy morphs into a glass.

    Both sets of alloys were scanned by an SSRL X-ray beam, the data fed into the Citrine database, and new machine learning results generated, which were used to prepare new samples that underwent another round of scanning and machine learning.

    By the experiment’s third and final round, Mehta said, the group’s success rate for finding metallic glass had increased from one out of 300 or 400 samples tested to one out of two or three samples tested. The metallic glass samples they identified represented three different combinations of ingredients, two of which had never been used to make metallic glass before.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 7:51 pm on October 16, 2017 Permalink | Reply
    Tags: Astronomers proposed the existence of neutron stars in 1934, , , , , , , , , , Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest, SLAC Labs,   

    From Stanford: “Stanford experts on LIGO’s binary neutron star milestone” 

    Stanford University Name
    Stanford University

    October 16, 2017
    Taylor Kubota
    (650) 724-7707
    tkubota@stanford.edu

    On August 17, 2017, the two detectors of Advanced LIGO, along with VIRGO, zeroed in on what appeared to be gravitational waves emanating from a pair of neutron stars spinning together – a long-held goal for the LIGO team.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    An alert went out to collaborators worldwide and within hours some 70 instruments turned their sites on the location a mere 310 million light-years away.

    2
    Artist’s rendering of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays that are shot out just seconds after the gravitational waves. Swirling clouds of material ejected from the merging stars glow with visible and other wavelengths of light. (Image credit: NSF/LIGO/Sonoma State University/A. Simonnet)

    Their combined observations, spanning the electromagnetic spectrum, confirm some of what physicists had theorized about this type of event and also open up new areas of research. Thousands of scientists contributed to this accomplishment, including many at Stanford University, and published the initial findings Oct. 16 in Physical Review Letters and The Astrophysical Journal Letters.

    [For science papers, see https://sciencesprings.wordpress.com/2017/10/16/from-hubble-nasa-missions-catch-first-light-from-a-gravitational-wave-event/ ]

    “It’s a frighteningly disordered, energetic place out there in the universe and gravitational waves added a new dimension to looking at it,” said Robert Byer, professor of applied physics at Stanford and member of LIGO who provided the laser for the initial detector. “For this event, that new dimension was complemented by the signals from the other electromagnetic wavelengths and all those together gave us a completely different view of what’s going on inside the neutron stars as they merged.”

    This observation and the others that are likely to follow could help further the understanding of General Relativity, the origins of elements heavier than iron, the evolution of stars and black holes, relativistic jets that squirt from black holes and neutron stars, and the Hubble constant, which is the cosmological parameter which determines the expansion rate of the universe.

    Stanford and LIGO

    LIGO is led by the Massachusetts Institute of Technology and the California Institute of Technology, but Stanford was brought into the collaboration in 1988, largely due to the ultra-clean, stable lasers developed by Byer. The Byer lab developed the chip for the laser in the initial LIGO detector, which they installed in the early 2000s and lasted the lifetime of the initial LIGO project, which concluded in 2010. Lasers for the Advanced LIGO built upon Byer’s earlier work, an effort led by Benno Wilkie of the Albert Einstein Institute Hannover, a former postdoctoral scholar in Stanford’s Ginzton lab.

    “We were looking for the problems that LIGO couldn’t actually worry about yet. We wanted to find those and solve them before they became roadblocks,” said Byer. “One thing that allowed Stanford to contribute to LIGO in these extraordinary ways is we have this long tradition of engineering and science working together – and that’s not common. Great credit also goes to our extraordinary graduate students who are the glue that hold it all together.”

    Daniel DeBra, professor emeritus of aeronautics and astronautics, designed the original platform for LIGO, a nested system so stable that, in the LIGO detection band, it moves no more than an atom relative to the movement of Earth’s surface. Another crucial element of the vibration isolation system is the silicate bonding technique used to suspend LIGO’s mirrors. As a visiting scholar at Stanford, Sheila Rowan of the University of Glasgow adapted this technique from previous work at Stanford on the Gravity Probe B telescope.

    The Dark Energy Camera (DECam), the instrument used by the Dark Energy Survey, was among the first cameras to see in optical light what the LIGO-VIRGO detectors observed in gravitational waves earlier that morning.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    DECam imaged the entire area within which the object was expected to be and helped confirm that the event was a unique object – and very likely the event LIGO had seen earlier that day.

    Many people at Stanford and the SLAC National Accelerator Laboratory are part of the Dark Energy Survey team. Aaron Roodman, professor and chair of particle physics and astrophysics at SLAC, developed, commissioned and continues to optimize the Active Optics System of DECam.

    Looking to the future, DeBra and colleagues including Brian Lantz, a senior research scientist who leads the Engineering Test Facility for LIGO at Stanford, are improving signal detection of Advanced LIGO by damping the effects of vibrations on the optics.

    Other faculty are improving the sensitivity of the Fermi Large Area Telescope (LAT), a instrument helmed by Peter Michelson, a professor of physics, that can both confirm the existence of a binary neutron star system and rule out other possible sources. Its sister instrument on Fermi, the Gamma-Ray Burst Monitor, detected a gamma ray burst coming from the location given by LIGO and VIRGO 14 seconds after the gravitational wave signal.

    LIGO is offline for scheduled upgrades for the next year, but many of the researchers are already working on LIGO Voyager, the third-generation of LIGO, which is anticipated to increase the sensitivity by a factor of 2 and would lead to an estimated 800 percent increase in event rate.

    “This is only a beginning. There are many innovations to come and I don’t know where we’re going to be in 10 years, 20 years, 30 years,” said Michelson. “The window is open and there are going to be mind-blowing surprises. That, to me, is the most exciting.”

    What’s so special about neutron stars

    A neutron star results when the core of a large star collapses and the atoms get crushed. The protons and electrons squeeze together and the remaining star is about 95 percent neutrons. A tablespoon full of neutron stars weighs as much as Mt. Everest.

    “Neutron stars have some of the strongest gravity you’ll find – black holes have the strongest – and thus they give us handles on studying strong-field gravity around them to see if it deviates at all from General Relativity,” said Mandeep Gill, the outreach coordinator at KIPAC at SLAC and Stanford, and a member of the Dark Energy Survey collaboration.

    Astronomers proposed the existence of neutron stars in 1934. They were first found in 1967, and then in 1975 a radio telescope observed the first instance of a binary neutron star system. From that discovery, Roger Blandford, professor of physics at Stanford, and colleagues confirmed predictions of the General Theory of Relativity.

    Blandford said the calculations related to the system Advanced LIGO saw are even more complicated because the stars are much closer together and could only be completed by a computer. This observation continues to support the General Theory of Relativity but Gill is hopeful that additional binary neutron star systems may begin to inform extension to the theory that could reveal how it fits with quantum theory, dark energy and dark matter.

    “One of the things I find terribly exciting about these observations is that not only do they confirm aspects of astronomical and relativistic precepts but they actually teach us things about nuclear physics that we don’t properly understand,” said Blandford. “We certainly have many things that we’ve speculated about and thought about – and I have to believe that some of that will be right – but some of it will be much more interesting than what we could anticipate.”

    As we observe more of these systems, which scientists anticipate, we may finally understand long-standing mysteries of neutron stars, like whether they have earthquakes on their crust or if, as suspected, they have small mountains that send out their own gravitational wave signal.

    “Even though we’ve been doing astronomy since the dawn of civilization, every time we turn on new instruments, we learn new things about what’s going on in the universe,” said Lantz. “If the elements heavier than iron are actually made in events like this, that stuff is here on Earth and it’s likely that was generated by events like this. It gives you sort of a way to reach out and touch the stars.”

    Blandford is also KIPAC Division Director in the Particle Physics and Astrophysics Directorate and professor of particle physics and astrophysics at SLAC; Byer is also a professor in SLAC’s Photon Science Directorate.

    Additional Stanford contributors to the LIGO multi-messenger observation include Edgard Bonilla, Riccardo Bassiri, Elliot Bloom, David Burke, Robert Cameron, James Chiang, Carissa Cirelli, C.E. Cunha, Christopher Davis, Seth Digel, Mattia Di Mauro, Richard Dubois, Martin Fejer, Warren Focke, Thomas Glanzman, Daniel Gruen, Ashot Markosyan, Manuel Meyer, Igor Moskalenko, Nicola Omedai, Elena Orlando, Troy Porter, Anita Reimer, Olaf Reimer, Leon Rochester, Aaron Roodman, Eli Rykoff, Brett Shapiro, Rafe Schindler, Jana B. Thayer, John Gregg Thayer, Giacomo Vianello and Risa Wechsler.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

    Stanford University Seal

     
  • richardmitnick 3:17 pm on August 11, 2017 Permalink | Reply
    Tags: SLAC Labs, , ,   

    From Symmetry: “A new search for dark matter 6800 feet underground” 

    Symmetry Mag

    Symmetry

    08/08/17
    Manuel Gnida

    Prototype tests of the future SuperCDMS SNOLAB experiment are in full swing.

    1
    Chris Smith/SLAC National Accelerator Laboratory)

    When an extraordinarily sensitive dark matter experiment goes online at one of the world’s deepest underground research labs, the chances are better than ever that it will find evidence for particles of dark matter—a substance that makes up 85 percent of all matter in the universe but whose constituents have never been detected.

    The heart of the experiment, called SuperCDMS SNOLAB, will be one of the most sensitive detectors for hypothetical dark matter particles called WIMPs, short for “weakly interacting massive particles.” SuperCDMS SNOLAB is one of two next-generation experiments (the other one being an experiment called LZ) selected by the US Department of Energy and the National Science Foundation to take the search for WIMPs to the next level, beginning in the early 2020s.

    SuperCDMS, at SNOLAB (Vale Inco Mine, Sudbury, Canada)

    “The experiment will allow us to enter completely unexplored territory,” says Richard Partridge, head of the SuperCDMS SNOLAB group at the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of Stanford University and SLAC National Accelerator Laboratory. “It’ll be the world’s most sensitive detector for WIMPs with relatively low mass, complementing LZ, which will look for heavier WIMPs.”

    LBNL LZ project at SURF

    The experiment will operate deep underground at Canadian laboratory SNOLAB inside a nickel mine near the city of Sudbury, where 6800 feet of rock provide a natural shield from high-energy particles from space, called cosmic rays. This radiation would not only cause unwanted background in the detector; it would also create radioactive isotopes in the experiment’s silicon and germanium sensors, making them useless for the WIMP search. That’s also why the experiment will be assembled from major parts at its underground location.

    A detector prototype is currently being tested at SLAC, which oversees the efforts of the SuperCDMS SNOLAB project.

    Colder than the universe

    The only reason we know dark matter exists is that its gravity pulls on regular matter, affecting how galaxies rotate and light propagates. But researchers believe that if WIMPs exist, they could occasionally bump into normal matter, and these collisions could be picked up by modern detectors.

    SuperCDMS SNOLAB will use germanium and silicon crystals in the shape of oversized hockey pucks as sensors for these sporadic interactions. If a WIMP hits a germanium or silicon atom inside these crystals, two things will happen: The WIMP will deposit a small amount of energy, causing the crystal lattice to vibrate, and it’ll create pairs of electrons and electron deficiencies that move through the crystal and alter its electrical conductivity. The experiment will measure both responses.

    “Detecting the vibrations is very challenging,” says KIPAC’s Paul Brink, who oversees the detector fabrication at Stanford. “Even the smallest amounts of heat cause lattice vibrations that would make it impossible to detect a WIMP signal. Therefore, we’ll cool the sensors to about one hundredth of a Kelvin, which is much colder than the average temperature of the universe.”

    These chilly temperatures give the experiment its name: CDMS stands for “Cryogenic Dark Matter Search.” (The prefix “Super” indicates that the experiment is more sensitive than previous detector generations.)

    The use of extremely cold temperatures will be paired with sophisticated electronics, such as transition-edge sensors that switch from a superconducting state of zero electrical resistance to a normal-conducting state when a small amount of energy is deposited in the crystal, as well as superconducting quantum interference devices, or SQUIDs, that measure these tiny changes in resistance.

    The experiment will initially have four detector towers, each holding six crystals. For each crystal material—silicon and germanium—there will be two different detector types, called high-voltage (HV) and interleaved Z-sensitive ionization phonon (iZIP) detectors. Future upgrades can further boost the experiment’s sensitivity by increasing the number of towers to 31, corresponding to a total of 186 sensors.

    2
    Four SuperCDMS SNOLAB iZIP detectors at the Stanford Nanofabrication Facility. Matt Cherry.

    3
    A SNOLAB Engineering Tower is installed in the dilution fridge to test cryogenic flex-cable readout configurations. Paul Brink.

    4
    High-density Vacuum Interface Board developed at Fermilab for readout of cryogenic detectors. Paul Brink.

    5
    SNOLAB prototype HV detector fabricated and packaged by Matt Cherry (SLAC) in SNOLAB prototype hardware. Matt Cherry.

    6
    SNOLAB Engineering Tower assembled by Tsuguo Aramaki (SLAC) and Xuji Zhao (Texas A&M). Paul Brink

    Working hand in hand

    The work under way at SLAC serves as a system test for the future SuperCDMS SNOLAB experiment. Researchers are testing the four different detector types, the way they are integrated into towers, their superconducting electrical connectors and the refrigerator unit that cools them down to a temperature of almost absolute zero.

    “These tests are absolutely crucial to verify the design of these new detectors before they are integrated in the experiment underground at SNOLAB,” says Ken Fouts, project manager for SuperCDMS SNOLAB at SLAC. “They will prepare us for a critical DOE review next year, which will determine whether the project can move forward as planned.” DOE is expected to cover about half of the project costs, with the other half coming from NSF and a contribution from the Canadian Foundation for Innovation.

    Important work is progressing at all partner labs of the SuperCDMS SNOLAB project. Fermi National Accelerator Laboratory is responsible for the cryogenics infrastructure and the detector shielding—both will enable searching for faint WIMP signals in an environment dominated by much stronger unwanted background signals. Pacific Northwest National Laboratory will lend its expertise in understanding background noise in highly sensitive precision experiments. A number of US universities are involved in various aspects of the project, including detector fabrication, tests, data analysis and simulation.

    The project also benefits from international partnerships with institutions in Canada, France, the UK and India. The Canadian partners are leading the development of the experiment’s data acquisition and will provide the infrastructure at SNOLAB.

    “Strong partnerships create a lot of synergy and make sure that we’ll get the best scientific value out of the project,” says Fermilab’s Dan Bauer, spokesperson of the SuperCDMS collaboration, which consists of 109 scientists from 22 institutions, including numerous universities. “Universities have lots of creative students and principal investigators, and their talents are combined with the expertise of scientists and engineers at the national labs, who are used to successfully manage and build large projects.”

    SuperCDMS SNOLAB will be the fourth generation of experiments, following CDMS-I at Stanford, CDMS-II at the Soudan mine in Minnesota, and a first version of SuperCDMS at Soudan, which completed operations in 2015.

    “Over the past 20 years we’ve been pushing the limits of our detectors to make them more and more sensitive for our search for dark matter particles,” says KIPAC’s Blas Cabrera, project director of SuperCDMS SNOLAB. “Understanding what constitutes dark matter is as fundamental and important today as it was when we started, because without dark matter none of the known structures in the universe would exist—no galaxies, no solar systems, no planets and no life itself.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:03 pm on May 4, 2011 Permalink | Reply
    Tags: , SLAC Labs,   

    From SLAC Today: “Seen Around SLAC: HELEN Has a New Home” 

    by Lori Ann White

    A 30-year-old laser built to simulate the conditions at the heart of a nuclear explosion arrived at SLAC last week, where members of the Linac Coherent Light Source’s Laser Science and Technology Department want to put it to a more peaceful use.
    i1
    SLAC LCLS

    The High Energy Laser Embodying Neodymium, or HELEN, is a neodymium-doped glass laser originally commissioned at Britain’s Atomic Weapons Establishment in 1979 in a ceremony presided over by Queen Elizabeth. But now that AWE [Atomic Weapons Establishment. in Britain] has a new, more powerful laser of its own called Orion, HELEN needed a new home, and LCLS scientists were only too happy to oblige.

    ‘ I’m very excited about this laser,’ said LCLS laser physicist Greg Hays, whose job it was to bring HELEN safely over from England. It may be 30 years old, he said, but it will still pack a punch in the kilo-joule range once it’s up and running: ‘ It’s essentially the grandfather of the National Ignition Facility at Lawrence Livermore National Laboratory, which is the world’s largest and most energetic laser, with a goal of achieving nuclear fusion and energy gain in the laboratory for the first time.

    The laser will probably be focused on the target chamber for the LCLS’s Matter in Extreme Conditions instrument.”

     
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