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  • richardmitnick 7:31 am on July 12, 2019 Permalink | Reply
    Tags: , , , , , SLAC National Accelerator Laboratory   

    From SLAC National Accelerator Lab: “Light dark matter is a thousand times less likely to bump into regular matter than previous astrophysical analyses allowed” 

    From SLAC National Accelerator Lab

    July 11, 2019
    Manuel Gnida

    1
    Simulation of the dark matter structure surrounding the Milky Way. Driven by gravity, dark matter forms dense structures, referred to as halos (bright areas), in which galaxies are born. The number and distribution of halos, and therefore also of galaxies, depends on the properties of dark matter, such as its mass and its likelihood to interact with normal matter. (Ethan Nadler/Risa Wechsler/Ralf Kaehler/SLAC National Accelerator Laboratory/Stanford University)

    A team led by scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University has narrowed down how strongly dark matter particles might interact with normal matter. Based on the number and distribution of small satellite galaxies seen orbiting our Milky Way, the team found this interaction to be at least a thousand times weaker than the strongest interaction allowed by previous astrophysical analyses.

    “Improving our understanding of these interactions is important because it’s one of the factors that helps us determine what dark matter can and cannot be,” said Risa Wechsler, director of the SLAC/Stanford Kavli Institute for Particle Astrophysics and Cosmology and the study’s senior author. The study can also help researchers refine their models for the evolution of the universe because dark matter and its interactions with gravity play such a fundamental role in how galaxies form, she said.

    Study lead author Ethan Nadler, a graduate student working with Wechsler, said, “Our results exclude dark matter properties in a mass range that has been largely unexplored before, nicely complementing the outcomes of other experiments that set tight limits for heavier dark matter particles.”

    The researchers recently published their results in The Astrophysical Journal Letters.

    The ‘missing satellites conundrum

    Most of the structure in today’s universe can be explained with a quite simple dark matter model. It assumes that dark matter is relatively “cold,” meaning it moved very slowly compared to the speed of light, and “collisionless,” meaning it doesn’t interact with itself or regular matter. As the universe expands, gravity causes dark matter to clump together and form dense dark matter halos. Dark matter also pulls in regular matter around it, concentrating regular matter and initiating galaxy formation inside dark matter halos.

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex Mittelmann Cold creation


    Simulation of the formation of the dark matter structure surrounding the Milky Way, from the early universe to today. Gravity makes dark matter clump together and form dense structures, referred to as halos (bright areas). The number and distribution of halos depends on the properties of dark matter, such as its mass and its likelihood to interact with normal matter. Galaxies are thought to form inside these halos. In a new study, SLAC and Stanford researchers have used measurements of faint satellite galaxies orbiting the Milky Way to derive limits on how often dark matter particles can possibly collide with regular matter particles. (Ethan Nadler/Risa Wechsler/R. Kaehler/SLAC National Accelerator Laboratory/Stanford University)

    This “cold dark matter” model works well on very large scales, including clusters of galaxies, and describes how typical galaxies are clustered in the universe. But on much smaller scales – for galaxies smaller than our Milky Way, for example – the simple model seemed to cause problems.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    It predicts that the Milky Way’s halo is surrounded by thousands of smaller subhalos, so there should be also thousands of smaller satellite galaxies orbiting our galaxy. Yet, by the early 2000s, researchers only knew of about 10 of them.

    “The apparent discrepancy between observations and predictions made people think there is a serious issue with the model, but recently this has become less of a problem,” Nadler said.

    “Increasingly sensitive astrophysical surveys have discovered many more faint satellite galaxies, and we expect next-generation instruments like the Large Synoptic Survey Telescope to find hundreds more if the simplest cold dark matter model is correct.

    LSST


    LSST Camera, built at SLAC



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


    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Thus, if fewer galaxies are observed, this could indicate that the simplest model is not exactly correct,” he said. “At the same time, we don’t expect the smallest halos to host galaxies, so understanding the connection between galaxies and halos is crucial to make conclusions about the nature of dark matter.”

    Limiting what dark matter can be

    One way the dark matter model can be modified is by assuming that dark matter was produced in a “warmer” state in the early universe, meaning it moved faster than in the simple model and was less likely to clump. This would result in a smaller number of dark matter halos and cut down the number of observable satellite galaxies. Because the mass of dark matter controls its velocity when it was produced in the early universe, the abundance of satellites can be used to determine the minimum mass of warm dark matter particles.

    Here, the researchers looked at a different property of dark matter in other non-standard models: its interaction with normal matter. They showed that collisions between dark matter particles and regular matter particles like protons and neutrons would also reduce the observable satellite population.

    “If the interaction is very strong, it erases small dark matter halos and suppresses a lot of the small structure,” Wechsler said. “But we can actually see some smaller structures based on the tiny galaxies they host, so the interaction can’t be too strong either.” In other words, the number of observable satellite galaxies provides a path to learning about these fundamental interactions.

    In their study, the team varied the strength of the collision interaction in their dark matter model and ran simulations to predict how that affected the distribution of dark matter halos. Then, they tried to fit known satellite galaxies into the halos.

    “What’s really exciting is that our study nicely bridges experimental observations of faint galaxies today with theories of dark matter and its behavior in the early universe. It connects a lot of pieces, and by doing so it tells us something very profound about dark matter,” Nadler said.

    The researchers found that in order to make everything fit together, dark matter particles with relatively low mass must interact at least a thousand times more weakly with normal matter than the previous limit. Before this work, the leading constraint in this mass range were set by astrophysical studies based on the cosmic microwave background, the earliest light in the universe. Meanwhile, direct detection experiments, which search for signs of dark matter with sensitive underground detectors, set stringent limits on the interaction strength for heavier dark matter particles, making studies of satellite galaxies highly complementary to those experiments.

    “Although we still don’t know what dark matter is made of, our results are a step forward that sets tighter limits on what it actually can be,” Nadler said.

    Other researchers involved in the study were Vera Gluscevic at the University of Southern California and Kimberly Boddy at Johns Hopkins University. Financial support came from the National Science Foundation and the Department of Energy.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 11:11 am on June 26, 2019 Permalink | Reply
    Tags: , , Cryo-EM imaging, First snapshots of trapped CO2 molecules shed new light on carbon capture, , SLAC National Accelerator Laboratory   

    From SLAC National Accelerator Lab: “First snapshots of trapped CO2 molecules shed new light on carbon capture” 

    From SLAC National Accelerator Lab

    June 26, 2019
    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282

    A new twist on cryo-EM imaging reveals what’s going on inside MOFs, highly porous nanoparticles with big potential for storing fuel, separating gases and removing carbon dioxide from the atmosphere.

    1
    Scientists used instruments at the Stanford-SLAC Cryo-EM Facilities (left) to make the first images of carbon dioxide molecules trapped in molecular cages (right) within a porous nanoparticle. The results will aid efforts to develop nanoparticles for capturing and storing liquids and gases, including carbon dioxide. (SLAC National Accelerator Laboratory/Li et al., Matter, 26 June 2019)

    Scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have taken the first images of carbon dioxide molecules within a molecular cage ­­– part of a highly porous nanoparticle known as a MOF, or metal-organic framework, with great potential for separating and storing gases and liquids.

    The images, made at the Stanford-SLAC Cryo-EM Facilities, show two configurations of the CO2 molecule in its cage, in what scientists call a guest-host relationship; reveal that the cage expands slightly as the CO2 enters; and zoom in on jagged edges where MOF particles may grow by adding more cages.

    “This is a groundbreaking achievement that is sure to bring unprecedented insights into how these highly porous structures carry out their exceptional functions, and it demonstrates the power of cryo-EM for solving a particularly difficult problem in MOF chemistry,” said Omar Yaghi, a professor at the University of California, Berkeley and a pioneer in this area of chemistry, who was not involved in the study.

    The research team, led by SLAC/Stanford professors Yi Cui and Wah Chiu, described the study today in the journal Matter.

    2
    Cryo-EM images show a slice through a single MOF particle in atomic detail (left), revealing cage-like molecules (center) that can trap other molecules inside. The image at right shows carbon dioxide molecules trapped in one of the cages – the first time this has ever been observed. Bottom right, a drawing of the molecular structure of the cage and the trapped carbon dioxide. (Li et al., Matter, 26 June 2019)

    Tiny specks with enormous surfaces

    MOFs have the largest surface areas of any known material. A single gram, or three hundredths of an ounce, can have a surface area nearly the size of two football fields, offering plenty of space for guest molecules to enter millions of host cages.

    Despite their enormous commercial potential and two decades of intense, accelerating research, MOFs are just now starting to reach the market. Scientists across the globe engineer more than 6,000 new types of MOF particles per year, looking for the right combinations of structure and chemistry for particular tasks, such as increasing the storage capacity of gas tanks or capturing and burying CO2 from smokestacks to combat climate change.

    “According to the Intergovernmental Panel on Climate Change, limiting global temperature increases to 1.5 degrees Celsius will require some form of carbon capture technology,” said Yuzhang Li, a Stanford postdoctoral researcher and lead author of the report. “These materials have the potential to capture large quantities of CO2, and understanding where the CO2 is bound inside these porous frameworks is really important in designing materials that do that more cheaply and efficiently.”

    One of the most powerful methods for observing materials is transmission electron microscopy, or TEM, which can make images in atom-by-atom detail. But many MOFs, and the bonds that hold guest molecules inside them, melt into blobs when exposed to the intense electron beams needed for this type of imaging.

    A few years ago, Cui and Li adopted a method that’s been used for many years to study biological samples: Freeze samples so they hold up better under electron bombardment. They used an advanced TEM instrument at the Stanford Nano Shared Facilities to examine flash-frozen samples containing dendrites – finger-like growths of lithium metal that can pierce and damage lithium-ion batteries – in atomic detail for the first time.

    Atomic images, one electron at a time

    For this latest study, Cui and Li used instruments at the Stanford-SLAC Cryo-EM Facilities, which have much more sensitive detectors that can pick up signals from individual electrons passing through a sample. This allowed the scientists to make images in atomic detail while minimizing the electron beam exposure.

    3
    In a new study, researchers trapped carbon dioxide molecules in highly porous nanoparticles called MOFs, flash-froze the particles in liquid nitrogen and examined them with cryo-EM at a Stanford-SLAC facility. The process allowed them to obtain the first atomic-scale images of individual carbon dioxide molecules within the particle’s cage-like pores. (Li et al., Matter, 26 June 2019)

    The MOF they studied is called ZIF-8. It came in particles just 100 billionths of a meter in diameter; you’d need to line about 900 of them up to match the width of a human hair. “It has high commercial potential because it’s very cheap and easy to synthesize,” said Stanford postdoctoral researcher Kecheng Wang, who played a key role in the experiments. “It’s already being used to capture and store toxic gases.”

    Cryo-EM not only let them make super-sharp images with minimal damage to the particles, but it also kept the CO2 gas from escaping while its picture was being taken. By imaging the sample from two angles, the investigators were able to confirm the positions of two of the four sites where CO2 is thought to be weakly held in place inside its cage.

    “I was really excited when I saw the pictures. It’s a brilliant piece of work,” said Stanford Professor Robert Sinclair, an expert in using TEM to study materials who helped interpret the team’s results. “Taking pictures of the gas molecules inside the MOFs is an incredible step forward.”

    4
    The new cryo-EM images also reveal step-like features at the edges of MOF particles (upper right) where scientists think new cages may form as the particle grows (bottom right). (Li et al., Matter, 26 June 2019)

    Major funding for this study came from the National Institutes of Health and the Department of Energy.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 10:17 am on June 22, 2019 Permalink | Reply
    Tags: "Scientists make first high-res movies of proteins forming crystals in a living cell", , “The protein molecules are self-assembling building blocks and they will spontaneously form themselves into crystals No enzyme is required.”, , Microbial cell division, , Single-molecule tracking, SLAC National Accelerator Laboratory, Stimulated emission depletion, Super-resolution fluorescence microscopy   

    From SLAC National Accelerator Lab: “Scientists make first high-res movies of proteins forming crystals in a living cell” 

    From SLAC National Accelerator Lab

    June 21, 2019
    Glennda Chui

    A close-up look at how microbes build their crystalline shells has implications for understanding how cell structures form, preventing disease and developing nanotechnology.

    Scientists have made the first observations of proteins assembling themselves into crystals, one molecule at a time, in a living cell. The method they used to watch this happen – an extremely high-res form of molecular moviemaking ­– could shed light on other important biological processes and help develop nanoscale technologies inspired by nature.

    Led by researchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, the study was published in Nature Communications today.

    “I’ve been super-excited to watch and track the movements of single molecules as they form this fascinating crystalline shell on the surface of a microbe,” said Stanford professor and study co-author W.E. Moerner, who shared the 2014 Nobel Prize in chemistry for stunning advances in pushing the boundaries of what optical microscopes can see. “We can look on a very fine scale and see the molecules arranging themselves in the shell. It’s the first time we’ve been able to do this.”

    The study focused on a bacterium called Caulobacter crescentus that lives in lakes and streams. It’s one of many microbes that sport a very thin crystalline shell, known as a surface layer or S-layer, made of identical protein building blocks.

    2
    An Illustration shows the cylindrical stalk of the microbe covered in a crystalline protein shell known as an S-layer. (Greg Stewart/SLAC National Accelerator Laboratory)

    3
    This illustration zooms in to show six-sided protein crystal “tiles” forming at top left and far right. (Greg Stewart/SLAC National Accelerator Laboratory)

    Scientists have been trying to figure out what roles these brittle shells play in the lives of their owners and how they come together to smoothly cover a microbe’s curvy surfaces. The research is driven not just by a desire to understand how nature works, but also by the possibility of applying that knowledge to create new types of nanotechnology – for instance, by using the protein shells as scaffolds for building “engineered living materials.” The shells also offer a potential target for drugs aimed at disarming infectious bacteria.

    In this study, the research team used two established techniques that transcend the previous resolution limitations of optical microscopy – super-resolution fluorescence microscopy and single-molecule tracking – to watch individual building blocks move around the surfaces of living bacteria and assemble themselves into a shell. The resulting images and movies revealed how protein building blocks crystallize to form the bacterium’s S-layer coat.

    “It’s like watching a pile of bricks self-assemble into a two-story house,” said Jonathan Herrmann, a PhD student at Stanford and SLAC who along with fellow Stanford PhD students Colin Comerci and Josh Yoon carried out the bulk of the work.

    4
    A still image shows the tracks (red, white and blue lines) of individual protein molecules moving around the surface of a microbe over a period of 60 seconds. One of the molecules has just bound to an existing patch of the shell (bottom), which is labeled with a green fluorescent tag. The microbe is outlined in orange. (Josh Yoon, Colin Comerci, Jonathan Herrmann/Stanford University)


    This high-res movie represents the first observation ever made of protein crystallization by a living cell. It shows single protein molecules (red) roving over the surface of a microbe over the course of two minutes; when they join an existing patch of the microbe’s shell (green) they crystallize like rock candy around a string. The molecules are tagged with fluorescent chemicals to make them visible. (Josh Yoon, Colin Comerci, Jonathan Herrmann/Stanford University)

    Following the glow

    Protein crystals are widespread in nature: in shells that surround many bacteria and almost all of the ancient microbes called Archaea, in the outer shells of viruses and even in the human eye. The bacteria that cause anthrax and salmonella infections have these crystalline shells; so does Clostridium difficile, which causes serious infections of the colon and intestines. A lot of research has been aimed at disrupting these shells to head off infection.

    The bacteria in this study don’t infect healthy people and are well-studied and understood, so they make good research subjects. Scientists know, among other things, that these bacteria can’t thrive without their shells, which are made from protein building blocks called RsaA. But shell assembly takes place at such a tiny scale that it had never been observed before.

    To watch it happen, the researchers stripped microbes of their S-layers and supplied them with synthetic RsaA building blocks labeled with chemicals that fluoresce in bright colors when stimulated with a particular wavelength of light.

    5
    These images show how a super-resolution fluorescence microscopy technique called STED produces much sharper images of microbial shell assembly (right) than a previous technique, confocal microscopy (left). Areas in red are places where the shell is growing: at the ends of the microbial cell, in the pinched middle section where it is preparing to divide and at cracks and defects in the shell. (Colin Comerci, Jonathan Herrmann/Stanford University)

    Then they tracked the glowing building blocks with single-molecule microscopy as they formed a shell that covered the microbe in a hexagonal, tile-like pattern in less than two hours. A technique called stimulated emission depletion (STED) microscopy allowed them to see structural details of the layer as small as 60 to 70 nanometers, or billionths of a meter, across – about one-thousandth the width of a human hair.

    The team discovered that the shell-building didn’t happen the way they thought: The RsaA blocks were not guided into position and joined to the shell by enzymes, which promote most biological reactions. Instead they randomly moved around, found a patch of existing shell and joined it, like rock candy crystallizing around a string dipped in sugar water.

    “The protein molecules are self-assembling building blocks, and they will spontaneously form themselves into crystals,” Herrmann said. “No enzyme is required.”

    6
    An illustration shows how protein building blocks secreted by a microbe (at arrows) travel over its surface until they encounter its growing crystalline shell. There they join one of the six-sided units that tile the microbe’s surface, crystallizing like rock candy around a string. (Greg Stewart/SLAC National Accelerator Laboratory)

    A new way of seeing

    Since the flat crystalline shell can never perfectly fit the constantly changing 3-D shape of the microbe – “It’s not a huge leap to say that if you try to bend the sheet to fit the microbe, you have to break it,” Comerci said – there are always small defects and gaps in coverage, and those places, he said, are where they saw the shell grow.

    “For the first time,” he said, “we were able to watch the S-layer proteins do things on their own.”

    7
    Sketch showing where the microbe’s crystalline shell would be expected to crack, based on the curvature of its surface as it grows and prepares to divide. The predicted cracks and defects are shown here in white. These are places where the crystalline shell tends to grow. (Colin Comerci/Stanford University)

    8
    A closer look at areas where shell growth is occurring. Green areas are existing patches of shell; red areas are new growth at cracks, the ends (poles) of the microbial cell and in the middle, where the microbe is growing and preparing to divide. (Colin Comerci, Jonathan Herrmann/Stanford University)

    This new way of observing shell formation “is opening up a new way to understand and eventually manipulate surface layer structures, both in living organisms and in isolation,” said co-author Soichi Wakatsuki, a professor at SLAC and Stanford who leads the Biological Sciences Division at the lab’s Stanford Synchrotron Radiation Lightsource.

    SLAC/SSRL

    “Now that we know how they assemble, we can modify their properties so they can do specific types of work, like forming new types of hybrid materials or attacking biomedical problems.”

    The next step, researchers said, is to find out how the crystallization process starts using higher resolution X-ray and electron imaging available at SLAC: How do the very first bits of the shell crystallize without the equivalent of the rock candy string?

    Optical microscopy for this study was carried out at the Moerner lab at Stanford. Researchers from the University of British Columbia and from Professor Lucy Shapiro’s laboratory at Stanford also contributed to this work, which was funded in part by the National Institute of General Medical Sciences and the Chan Zuckerberg Biohub. Work in Wakatsuki’s labs at SLAC and Stanford was partly funded by a Laboratory Directed Research and Development grant from SLAC and by the DOE Office of Biological and Environmental Research. The Stanford Synchrotron Radiation Lightsource is a DOE Office of Science user facility.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 5:11 pm on June 20, 2019 Permalink | Reply
    Tags: , , LZ experiment at SURF, , , Search for WIMPS, SLAC National Accelerator Laboratory   

    From SLAC National Accelerator Lab: “SLAC sends off woven grids for LUX-ZEPLIN dark matter detector” 

    From SLAC National Accelerator Lab

    June 20, 2019
    Manuel Gnida

    Four large meshes made from 2 miles of metal wire will extract potential signals of dark matter particles.

    The ultra-sensitive LUX-ZEPLIN (LZ) detector is scheduled to begin its search for elusive dark matter next year.

    LBNL LZ project at SURF, Lead, SD, USA

    At its core: a large tank filled with 10 metric tons of liquid xenon whose atoms would produce telltale signals when struck by dark matter particles. Inside the tank, four high-voltage grids – fine circular metal meshes, each 5 feet in diameter – are needed to extract these signals.

    Over the past few months, the LZ team at the Department of Energy’s SLAC National Accelerator Laboratory, which is part of the international LZ collaboration of 250 scientists from 37 institutions, has carefully woven the grids from 2 miles of thin stainless steel wire, and yesterday they sent the last one on its way to the Sanford Underground Research Facility (SURF) in South Dakota, where the LZ detector is being assembled.


    Weaving the high-voltage grids of the LUX-ZEPLIN dark matter experiment. (Farrin Abbott/SLAC National Accelerator Laboratory)

    “Completion of the delivery of the grids from SLAC is one of the most critical project milestones,” said LZ Project Director Murdoch “Gil” Gilchriese of DOE’s Lawrence Berkeley National Laboratory, which leads the project.

    “Congratulations to the grids team.”

    The quality of the grids is critical to LZ’s performance, and making them was a major challenge, said Tom Shutt, one of the directors of SLAC’s LZ team: “It took us about four years to develop the design and to manufacture and test them. It’s exciting that we’re now integrating them into the detector.” The team’s efforts included inventing a clever way of weaving the grids from metal wires.

    Rare collisions with dark matter

    Scientists have overwhelming evidence that the matter we can see makes up only a small fraction of the universe. About 85 percent of matter is invisible and interacts with everything else almost entirely through gravity. This mysterious substance is called “dark matter,” and researchers believe it’s composed of particles, just like ordinary matter is made of fundamental particles. Yet, dark matter’s building blocks have yet to show up in experiments.

    Scientists have been trying to detect dark matter particles by putting tanks of liquefied noble gases, like xenon, deep underground. Most dark matter particles rush through these tanks unhindered while traveling through our planet as if it were made of air. But from time to time, scientists theorize, a particle might collide with a noble gas atom and produce a signal that reveals dark matter’s presence and nature.

    As the newest generation of this type of “direct detection” dark matter experiment, LZ will be hundreds of times more sensitive to a particular type of dark matter candidate, called weakly interacting massive particles (WIMPs), than its predecessor.


    Dark matter hunt with the LZ experiment. (Greg Stewart/SLAC National Accelerator Laboratory)

    From collisions to flashes of light

    If and when a WIMP particle hits a xenon atom in LZ’s tank, two things will happen: The atom will emit a flash of light that is recorded by nearly 500 light-sensitive detectors, called photomultiplier tubes (PMTs), at the top and bottom of the tank. The atom will also release electrons, and that’s where the high-voltage grids come in.

    Two of the grids – the cathode at the bottom and the gate at the top – will help create an electric field that pushes electrons through the liquid xenon toward the top of the tank. There, they’ll be extracted from the liquid by a field between the gate and anode, which sits just below the top PMT array within a tightly controlled layer of xenon gas. In the gas, the electrons create another flash of light. A characteristic combination of two light flashes signals the arrival of a WIMP.

    “Establishing the electric field is critical to be able to distinguish between potential dark matter signals and background signals,” said Ryan Linehan, a Stanford University graduate student on SLAC’s LZ team.

    2
    Four high-voltage grids inside LZ’s tank of liquid xenon. The cathode and gate grids create an electric field that pushes electrons through the liquid xenon toward the top of the tank. There, a field between the gate and anode grids extracts the electrons. They enter a thin layer of xenon gas that floats atop the liquid, where they create a flash of light. A fourth grid at the bottom of the xenon tank shields the bottom PMT array from the high fields above. (Greg Stewart/SLAC National Accelerator Laboratory)

    A fourth grid at the bottom of the xenon tank will shield the bottom PMT array from the high electric fields above.

    Weaving a ‘metal fabric’

    To build the grids, LZ engineers and scientists had to solve a number of technical challenges. For instance, the grids can produce the required uniform electric field only if they stay very flat when mounted horizontally inside the xenon tank. They must also be transparent enough so that they don’t stop light from reaching the PMTs. To further complicate things, there are no commercially available grids in the size the LZ team needed, so they had to find a way to build their own.

    The crucial idea came from SLAC mechanical engineer Knut Skarpaas. He designed a loom similar to those used for weaving fabric. But instead of thread, LZ’s loom wove metal wires about the size of a human hair into fine meshes with wires only millimeters apart (see video at the top of this article). And instead of weaving the “fabric” on an ordinary production floor, the loom operated in a clean room to avoid contamination.

    3
    Members of SLAC’s LZ team with the loom they used to weave high-voltage grids for the next-gen dark matter experiment. (Farrin Abbott/SLAC National Accelerator Laboratory)

    Ramping up the voltage

    Once a metal mesh was woven, LZ folks sandwiched it between two metal rings and cut out a circular piece of the right size. Then, they carefully transferred the circular grids one by one to a customized test vessel and checked their performance.

    “Nobody had studied the behavior of such large grids under high fields and in this particular xenon environment before, so there was a lot we had to test and learn,” said Rachel Mannino, a postdoctoral researcher at the University of Wisconsin-Madison working with SLAC’s LZ team. “We were particularly worried about electron emissions from the wires, which can occur under high fields and would generate false signals in the detector.”

    The tests were done in xenon gas under high pressure. While slowly ramping up the voltage on the grids, the researchers used PMTs to search for potential hotspots where electrons leave the metal mesh. The results allowed the team to define grid operating conditions that minimize unwanted electron emissions.

    In addition, the gate grid was chemically treated to further reduce those nuisance emissions and improve the experiment’s ability to search for WIMPs with lower masses.

    4
    A SLAC team sets up a specialized vessel to test the performance of LZ’s high-voltage grids under high voltage and in a high-pressure xenon atmosphere. (Farrin Abbott/SLAC National Accelerator Laboratory)

    Getting ready for the dark matter hunt

    With the last grid on its way to SURF, the LZ team is now ready to put everything together.

    “We’ve recently begun building the detector core from the bottom up,” said SLAC’s Tomasz Biesiadzinski, one of the scientists in charge of detector integration, who splits his time between SLAC and SURF. “In the fall, we’ll move everything underground, where LZ’s outer layers are already being assembled, and integrate and connect all the parts. After all the years of preparation we’re finally getting close to collecting data.”

    LZ’s dark matter hunt is set to begin sometime next year. Then, it’ll be up to the WIMPs to show up.

    5
    LZ’s high-voltage grids are about 5 feet in diameter. Each of the four grids is woven from hundreds of metal wires thinner than a human hair – a total of two miles of wire for all four. (Farrin Abbott/SLAC National Accelerator Laboratory)

    Major support for LZ comes from the DOE Office of Science; South Dakota Science and Technology Authority; the U.K.’s Science & Technology Facilities Council; and from collaboration members in South Korea and Portugal.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 8:01 am on May 10, 2019 Permalink | Reply
    Tags: "Q&A: SLAC/Stanford researchers prepare for a new quantum revolution", , , , , , , , , , Quantum squeezing, SLAC National Accelerator Laboratory, The most exciting opportunities in quantum control make use of a phenomenon known as entanglement   

    From SLAC National Accelerator Lab- “Q&A: SLAC/Stanford researchers prepare for a new quantum revolution” 

    From SLAC National Accelerator Lab

    May 9, 2019
    Manuel Gnida

    Monika Schleier-Smith and Kent Irwin explain how their projects in quantum information science could help us better understand black holes and dark matter.

    The tech world is abuzz about quantum information science (QIS). This emerging technology explores bizarre quantum effects that occur on the smallest scales of matter and could potentially revolutionize the way we live.

    Quantum computers would outperform today’s most powerful supercomputers; data transfer technology based on quantum encryption would be more secure; exquisitely sensitive detectors could pick up fainter-than-ever signals from all corners of the universe; and new quantum materials could enable superconductors that transport electricity without loss.

    In December 2018, President Trump signed the National Quantum Initiative Act into law, which will mobilize $1.2 billion over the next five years to accelerate the development of quantum technology and its applications. Three months earlier, the Department of Energy had already announced $218 million in funding for 85 QIS research awards.

    The Fundamental Physics and Technology Innovation directorates of DOE’s SLAC National Accelerator Laboratory recently joined forces with Stanford University on a new initiative called Q-FARM to make progress in the field. In this Q&A, two Q-FARM scientists explain how they will explore the quantum world through projects funded by DOE QIS awards in high-energy physics.

    Monika Schleier-Smith, assistant professor of physics at Stanford, wants to build a quantum simulator made of atoms to test how quantum information spreads. The research, she said, could even lead to a better understanding of black holes.

    Kent Irwin, professor of physics at Stanford and professor of photon science and of particle physics and astrophysics at SLAC, works on quantum sensors that would open new avenues to search for the identity of the mysterious dark matter that makes up most of the universe.

    1
    Monika Schleier-Smith and Kent Irwin are the principal investigators of three quantum information science projects in high-energy physics at SLAC. (Farrin Abbott/Dawn Harmer/SLAC National Accelerator Laboratory)

    What exactly is quantum information science?

    Irwin: If we look at the world on the smallest scales, everything we know is already “quantum.” On this scale, the properties of atoms, molecules and materials follow the rules of quantum mechanics. QIS strives to make significant advances in controlling those quantum effects that don’t exist on larger scales.

    Schleier-Smith: We’re truly witnessing a revolution in the field in the sense that we’re getting better and better at engineering systems with carefully designed quantum properties, which could pave the way for a broad range of future applications.

    What does quantum control mean in practice?

    Schleier-Smith: The most exciting opportunities in quantum control make use of a phenomenon known as entanglement – a type of correlation that doesn’t exist in the “classical,” non-quantum world. Let me give you a simple analogy: Imagine that we flip two coins. Classically, whether one coin shows heads or tails is independent of what the other coin shows. But if the two coins are instead in an entangled quantum state, looking at the result for one “coin” automatically determines the result for the other one, even though the coin toss still looks random for either coin in isolation.

    Entanglement thus provides a fundamentally new way of encoding information – not in the states of individual “coins” or bits but in correlations between the states of different qubits. This capability could potentially enable transformative new ways of computing, where problems that are intrinsically difficult to solve on classical computers might be more efficiently solved on quantum ones. A challenge, however, is that entangled states are exceedingly fragile: any measurement of the system – even unintentional – necessarily changes the quantum state. So a major area of quantum control is to understand how to generate and preserve this fragile resource.

    At the same time, certain quantum technologies can also take advantage of the extreme sensitivity of quantum states to perturbations. One application is in secure telecommunications: If a sender and receiver share information in the form of quantum bits, an eavesdropper cannot go undetected, because her measurement necessarily changes the quantum state.

    Another very promising application is quantum sensing, where the idea is to reduce noise and enhance sensitivity by controlling quantum correlations, for instance, through quantum squeezing.

    What is quantum squeezing?

    Irwin: Quantum mechanics sets limits on how we can measure certain things in nature. For instance, we can’t perfectly measure both the position and momentum of a particle. The very act of measuring one changes the other. This is called the Heisenberg uncertainty principle. When we search for dark matter, we need to measure an electromagnetic signal extremely well, but Heisenberg tells us that we can’t measure the strength and timing of this signal without introducing uncertainty.

    Quantum squeezing allows us to evade limits on measurement set by Heisenberg by putting all the uncertainty into one thing (which we don’t care about), and then measuring the other with much greater precision. So, for instance, if we squeeze all of the quantum uncertainty in an electromagnetic signal into its timing, we can measure its strength much better than quantum mechanics would ordinarily allow. This lets us search for an electromagnetic signal from dark matter much more quickly and sensitively than is otherwise possible.

    2
    Kent Irwin (at left with Dale Li) leads efforts at SLAC and Stanford to build quantum sensors for exquisitely sensitive detectors. (Andy Freeberg/SLAC National Accelerator Laboratory)

    What types of sensors are you working on?

    Irwin: My team is exploring quantum techniques to develop sensors that could break new ground in the search for dark matter.

    We’ve known since the 1930s that the universe contains much more matter than the ordinary type that we can see with our eyes and telescopes – the matter made up of atoms. Whatever dark matter is, it’s a new type of particle that we don’t understand yet. Most of today’s dark matter detectors search for relatively heavy particles, called weakly interacting massive particles, or WIMPs.

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ project at SURF, Lead, SD, USA

    But what if dark matter particles were so light that they wouldn’t leave a trace in those detectors? We want to develop sensors that would be able to “see” much lighter dark matter particles.

    There would be so many of these very light dark matter particles that they would behave much more like waves than individual particles. So instead of looking for collisions of individual dark matter particles within a detector, which is how WIMP detectors work, we want to look for dark matter waves, which would be detected like a very weak AM radio signal.

    In fact, we even call one of our projects “Dark Matter Radio.” It works like the world’s most sensitive AM radio. But it’s also placed in the world’s most perfect radio shield, made up of a material called a superconductor, which keeps all normal radio waves out. However, unlike real AM radio signals, dark matter waves would be able to go right through the shield and produce a signal. So we are looking for a very weak AM radio station made by dark matter at an unknown frequency.

    Quantum sensors can make this radio much more sensitive, for instance by using quantum tricks such as squeezing and entanglement. So the Dark Matter Radio will not only be the world’s most sensitive AM radio; it will also be better than the Heisenberg uncertainty principle would normally allow.

    What are the challenges of QIS?

    Schleier-Smith: There is a lot we need to learn about controlling quantum correlations before we can make broad use of them in future applications. For example, the sensitivity of entangled quantum states to perturbations is great for sensor applications. However, for quantum computing it’s a major challenge because perturbations of information encoded in qubits will introduce errors, and nobody knows for sure how to correct for them.

    To make progress in that area, my team is studying a question that is very fundamental to our ability to control quantum correlations: How does information actually spread in quantum systems?

    The model system we’re using for these studies consists of atoms that are laser-cooled and optically trapped. We use light to controllably turn on interactions between the atoms, as a means of generating entanglement. By measuring the speed with which quantum information can spread in the system, we hope to understand how to design the structure of the interactions to generate entanglement most efficiently. We view the system of cold atoms as a quantum simulator that allows us to study principles that are also applicable to other physical systems.

    In this area of quantum simulation, one major thrust has been to advance understanding of solid-state systems, by trapping atoms in arrays that mimic the structure of a crystalline material. In my lab, we are additionally working to extend the ideas and tools of quantum simulation in new directions. One prospect that I am particularly excited about is to use cold atoms to simulate what happens to quantum information in black holes.

    3
    Monika Schleier-Smith (at center with graduate students Emily Davis and Eric Cooper) uses laser-cooled atoms in her lab at Stanford to study the transfer of quantum information. (Dawn Harmer/SLAC National Accelerator Laboratory)

    What do cold atoms have to do with black holes?

    Schleier-Smith: The idea that there might be any connection between quantum systems we can build in the lab and black holes has its origins in a long-standing theoretical problem: When particles fall into a black hole, what happens to the information they contained? There were compelling arguments that the information should be lost, but that would contradict the laws of quantum mechanics.

    More recently, theoretical physicists – notably my Stanford colleague Patrick Hayden – found a resolution to this problem: We should think of the black hole as a highly chaotic system that “scrambles” the information as fast as physically possible. It’s almost like shredding documents, but quantum information scrambling is much richer in that the result is a highly entangled quantum state.

    Although precisely recreating such a process in the lab will be very challenging, we hope to look at one of its key features already in the near term. In order for information scrambling to happen, information needs to be transferred through space exponentially fast. This, in turn, requires quantum interactions to occur over long distances, which is quite counterintuitive because interactions in nature typically become weaker with distance. With our quantum simulator, we are able to study interactions between distant atoms by sending information back and forth with photons, particles of light.

    What do you hope will happen in QIS over the next few years?

    Irwin: We need to prove that, in real applications, quantum technology is superior to the technology that we already have. We are in the early stages of this new quantum revolution, but this is already starting to happen. The things we’re learning now will help us make a leap in developing future technology, such as universal quantum computers and next-generation sensors. The work we do on quantum sensors will enable new science, not only in dark matter research. At SLAC, I also see potential for quantum-enhanced sensors in X-ray applications, which could provide us with new tools to study advanced materials and understand how biomolecules work.

    Schleier-Smith: QIS offers plenty of room for breakthroughs. There are many open questions we still need to answer about how to engineer the properties of quantum systems in order to harness them for technology, so it’s imperative that we continue to broadly advance our understanding of complex quantum systems. Personally, I hope that we’ll be able to better connect experimental observations with the latest theoretical advances. Bringing all this knowledge together will help us build the technologies of the future.

    See the full article here .


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    SLAC/LCLS II projected view


    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 11:18 am on April 15, 2019 Permalink | Reply
    Tags: "SLAC’s high-speed ‘electron camera’ films molecular movie in HD", , , , , How a bond in the ring breaks and atoms jiggle around for extended periods of time., , Researchers have made the first high-definition “movie” of ring-shaped molecules breaking open in response to light, , SLAC National Accelerator Laboratory, The results demonstrate how our unique instruments for studying ultrafast processes complement each other, This allows us to ask new questions about fundamental processes stimulated by light., UED-ultrafast electron diffraction instrument   

    From SLAC National Accelerator Lab: “SLAC’s high-speed ‘electron camera’ films molecular movie in HD” 

    From SLAC National Accelerator Lab

    April 15, 2019

    Manuel Gnida
    mgnida@slac.stanford.edu
    (650) 926-2632

    1
    This illustration shows snapshots of the light-triggered transition of the ring-shaped 1,3-cyclohexadiene (CHD) molecule (background) to its stretched-out 1,3,5-hexatriene (HT) form (foreground). The snapshots were taken with SLAC’s high-speed “electron camera” – an instrument for ultrafast electron diffraction (UED). (Greg Stewart/SLAC National Accelerator Laboratory)

    With an extremely fast “electron camera” at the Department of Energy’s SLAC National Accelerator Laboratory, researchers have made the first high-definition “movie” of ring-shaped molecules breaking open in response to light. The results could further our understanding of similar reactions with vital roles in chemistry, such as the production of vitamin D in our bodies.


    Visualization of a molecular movie made with SLAC’s electron camera, in which researchers have captured in atomic detail how a ring-shaped molecule opens up in the first 800 millionths of a billionth of a second after being hit by a laser flash. Ring-opening reactions like this one play important roles in chemistry, such as the light-driven synthesis of vitamin D in our bodies. (Thomas Wolf/PULSE Institute)

    A previous molecular movie of the same reaction, produced with SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, for the first time recorded the large structural changes during the reaction.


    This video describes how the Linac Coherent Light Source, an X-ray free-electron laser at SLAC National Accelerator Laboratory, provided the first direct measurements of how a ring-shaped gas molecule unravels in the millionths of a billionth of a second after it is split open by light. The measurements were compiled in sequence to form the basis for computer animations showing molecular motion. (SLAC National Accelerator Laboratory)

    Now, making use of the lab’s ultrafast electron diffraction (UED) instrument, these new results provide high-resolution details – showing, for instance, how a bond in the ring breaks and atoms jiggle around for extended periods of time.

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    August 5, 2015- With SLAC’s new apparatus for ultrafast electron diffraction – one of the world’s fastest “electron cameras” – researchers can study motions in materials that take place in less than 100 quadrillionths of a second. A pulsed electron beam is created by shining laser pulses on a metal photocathode. The beam gets accelerated by a radiofrequency field and focused by a magnetic lens. Then it travels through a sample and scatters off the sample’s atomic nuclei and electrons, creating a diffraction image on a detector. Changes in these diffraction images over time are used to reconstruct ultrafast motions of the sample’s interior structure. (SLAC National Accelerator Laboratory)

    “The details of this ring-opening reaction have now been settled,” said Thomas Wolf, a scientist at the Stanford Pulse Institute of SLAC and Stanford University and leader of the research team. “The fact that we can now directly measure changes in bond distances during chemical reactions allows us to ask new questions about fundamental processes stimulated by light.”

    SLAC scientist Mike Minitti, who was involved in both studies, said, “The results demonstrate how our unique instruments for studying ultrafast processes complement each other. Where LCLS excels in capturing snapshots with extremely fast shutter speeds of only a few femtoseconds, or millionths of a billionth of a second, UED cranks up the spatial resolution of these snapshots. This is a great result, and the studies validate one another’s findings, which is important when making use of entirely new measurement tools.”

    LCLS Director Mike Dunne said, “We’re now making SLAC’s UED instrument available to the broad scientific community, in addition to enhancing the extraordinary capabilities of LCLS by doubling its energy reach and transforming its repetition rate. The combination of both tools uniquely positions us to enable the best possible studies of fundamental processes on ultrasmall and ultrafast scales.”

    The team reported their results today in Nature Chemistry.

    Molecular movie in HD

    This particular reaction has been studied many times before: When a ring-shaped molecule called 1,3-cyclohexadiene (CHD) absorbs light, a bond breaks and the molecule unfolds to form the almost linear molecule known as 1,3,5-hexatriene (HT). The process is a textbook example of ring-opening reactions and serves as a simplified model for studying light-driven processes during vitamin D synthesis.

    In 2015, researchers studied the reaction with LCLS, which resulted in the first detailed molecular movie of its kind and revealed how the molecule changed from a ring to a cigar-like shape after it was struck by a laser flash. The snapshots, which initially had limited spatial resolution, were brought further into focus through computer simulations.

    4
    Researchers created the first atomic-resolution movie of the ring-opening reaction of 1,3-cyclohexadiene (CHD) with an “electron camera” called UED. Bottom: The UED electron beam accurately measures the distances between pairs of atoms in the CHD molecule as the reaction proceeds. The distance between each pair is represented by a colored line in the graph. Variations in the distances as the molecule changes shape represent the molecular movie. Top: Visualization of the molecular structure corresponding to the distance distribution measured at about 380 femtoseconds into the reaction (dashed line at bottom). (David Sanchez/Stanford University)

    The new study used UED – a technique in which researchers send an electron beam with high energy, measured in millions of electronvolts (MeV), through a sample – to precisely measure distances between pairs of atoms.


    Taking snapshots of these distances at different intervals after an initial laser flash and tracking how they change allows scientists to create a stop-motion movie of the light-induced structural changes in the sample.

    The electron beam also produces strong signals for very dilute samples, such as the CHD gas used in the study, said SLAC scientist Xijie Wang, director of the MeV-UED instrument.

    3
    SLAC Megaelectronvolt Ultrasfast Electron Diffraction Instrument: MeV-UED

    “This allowed us to follow the ring-opening reaction over much longer periods of time than before.”

    Surprising details

    The new data revealed several surprising details about the reaction.

    They showed that the movements of the atoms accelerated as the CHD ring broke, helping the molecules rid themselves of excess energy and accelerating their transition to the stretched-out HT form.

    The movie also captured how the two ends of the HT molecule jiggled around as the molecules became more and more linear. These rotational motions went on for at least a picosecond, or a trillionth of a second.

    “I would have never thought these motions would last that long,” Wolf said. “It demonstrates that the reaction doesn’t end with the ring opening itself and that there is much more long-lasting motion in light-induced processes than previously thought.”

    A method with potential

    The scientists also used their experimental data to validate a newly developed computational approach for including the motions of atomic nuclei in simulations of chemical processes.

    “UED provided us with data that have the high spatial resolution needed to test these methods,” said Stanford chemistry professor and PULSE researcher Todd Martinez, whose group led the computational analysis. “This paper is the most direct test of our methods, and our results are in excellent agreement with the experiment.”

    In addition to advancing the predictive power of computer simulations, the results will help deepen our understanding of life’s fundamental chemical reactions, Wolf said: “We’re very hopeful our method will pave the way for studies of more complex molecules that are even closer to the ones used in life processes.”

    Other research institutions involved in this study were the University of York, UK; University of Nebraska-Lincoln; University of Potsdam, Germany; University of Edinburgh, UK; and Brown University. Large parts of this work were financially supported by the DOE Office of Science. SLAC’s MeV-UED instrument is part of LCLS, a DOE Office of Science user facility.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 3:45 pm on April 12, 2019 Permalink | Reply
    Tags: "SLAC develops novel compact antenna for communicating where radios fail", A high Q piezoelectric resonator as a portable VLF transmitter, , SLAC National Accelerator Laboratory   

    From SLAC National Accelerator Lab: “SLAC develops novel compact antenna for communicating where radios fail” 

    From SLAC National Accelerator Lab

    April 12, 2019

    1
    A new type of pocket-sized antenna, developed at SLAC, could enable mobile communication in situations where conventional radios don’t work, such as under water, through the ground and over very long distances through air. (Greg Stewart/SLAC National Accelerator Laboratory)

    The 4-inch-tall device could be used in portable transmitters for rescue missions and other challenging applications demanding high mobility.

    The device emits very low frequency (VLF) radiation with wavelengths of tens to hundreds of miles. These waves travel long distances beyond the horizon and can penetrate environments that would block radio waves with shorter wavelengths. While today’s most powerful VLF technology requires gigantic emitters, this antenna is only four inches tall, so it could potentially be used for tasks that demand high mobility, including rescue and defense missions.

    “Our device is also hundreds of times more efficient and can transmit data faster than previous devices of comparable size,” said SLAC’s Mark Kemp, the project’s principal investigator. “Its performance pushes the limits of what’s technologically possible and puts portable VLF applications, like sending short text messages in challenging situations, within reach.”

    The SLAC-led team reported their results today in Nature Communications.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 9:19 am on April 9, 2019 Permalink | Reply
    Tags: Children’s Museum of Indianapolis, Mission Jurassic, , SLAC National Accelerator Laboratory,   

    From SLAC National Accelerator Lab: “A mile-long graveyard of Jurassic fossils sparks a new international science collaboration” 

    From SLAC National Accelerator Lab

    March 28, 2019
    Ali Sundermier

    1
    Kimberly Calkins and Dallas Evans, lead curator of natural science and paleontology, with a sauropod femur at the upper sauropod quarry of The Jurassic Mile dig site. (Children’s Museum of Indianapolis)

    The Children’s Museum of Indianapolis announced plans this week for Mission Jurassic, a project that will support paleontological excavation of a fossil-rich plot of land in northern Wyoming. The project will bring together scientists from around the world, including the Department of Energy’s SLAC National Accelerator Laboratory, to reveal dramatic new secrets about the world of millions of years ago.

    “Mission Jurassic is a wonderful project because it’s not just an isolated fossil – it’s a suite of different organisms, including dinosaurs and plants, in a single location,” says SLAC scientist Nick Edwards. “We hope that through our involvement in this project, we will contribute some new information to the preservation, chemistry and maybe even the basic understanding of these extinct organisms, ancient ecosystems, and Earth history on the broader scale.”

    The Children’s Museum will serve as the Mission Jurassic leader. The project is made possible through a lead gift from Lilly Endowment Inc. Spearheaded by Phil Manning and Victoria Egerton of the University of Manchester in England, both scientists-in-residence at The Children’s Museum, more than 100 scientists from three countries will join forces to investigate the rare confluence of Jurassic Period fossils, trackways and fossilized plants. The site will provide clues that promise to tell a more complete story about the Jurassic Period.

    “We have been using SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) for over a decade to help map the subtle changes in chemistry that are a function of burial environments,” Manning says.

    SLAC SSRL Campus


    SLAC SSRL PEP collider map


    SLAC/SSRL

    “This work has real-world impact on how we might plan the long-term burial and disposal of waste in the 21st Century. We use the fossil record as a ‘hindsight laboratory’ that can better inform science on the mass transfer of compounds from the biosphere into the lithosphere”.

    The Jurassic Mile

    Project leaders are calling the fossil-rich, mile-square plot of land the Jurassic Mile. There are four main quarries within the multi-level, 640-acre site that offer a diverse assemblage of Morrison Formation articulated and semi-articulated dinosaurs. It has also yielded associated animals, fossil plants and dinosaur trackways of the Late Jurassic Period, 150 million years ago.

    Nearly 600 specimens weighing more than six tons have been collected from this site over the past two years, despite the fact that only a fraction of the site has been explored. They include the bones of an 80-foot-long sauropod (Brachiosaur) and 90-foot-long Diplodocid. A 6-foot-6-inch sauropod scapula (shoulder bone) and several blocks containing articulated bones are among the material collected during the 2018 field season. A 5-foot-1-inch femur was revealed at the announcement on March 25, 2019.

    Probing our world at the atomic level

    SLAC, a key partner working with the University of Manchester team, will shine bright X-rays onto the fossils at the SSRL, a DOE Office of Science user facility that produces X-ray beams perfectly tailored for probing the world at the atomic and molecular level. New imaging techniques being developed by the team have already resulted in multiple high-impact scientific publications.

    “Our primary instrument at SSRL is unique because it can do elemental imaging, which tells us where the elements are in fossils, and it can also do absorption spectroscopy, which tells us what chemical state they’re in,” says Uwe Bergmann, a distinguished staff scientist at SLAC. “It allows us to detect a wide range of important biological and geochemical elements, from light elements like phosphorous and sulfur all the way to the transition metals.”

    Specimens from the well-preserved fossil remains at the Jurassic Mile site will form the basis for a major expansion of The Children’s Museum of Indianapolis’ permanent Dinosphere exhibit that will add creatures from the Jurassic Period. The project is already utilizing cutting-edge science, from particle accelerators to some of the most powerful computers on the planet, to help resurrect the Jurassic dinosaurs and add momentum to the process of unearthing the lost world and forgotten lives.

    This article is based on a press release from The Children’s Museum of Indianapolis.

    From the press release, no image credits:

    3
    4

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC/LCLS


    SLAC/LCLS II projected view


    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 10:05 am on April 4, 2019 Permalink | Reply
    Tags: A new method could turn random fluctuations in the intensity of laser pulses from a nuisance into an advantage facilitating studies of these fundamental interactions., In a computational process that borrows ideas from machine learning researchers can then turn these data into a visualization of the X-ray pulse’s effects on the sample., In addition we need to control the time delay between them very well., Pump-probe experiments therefore typically require that we first prepare well-defined short pulses that are less random, , SLAC National Accelerator Laboratory, Taking advantage of X-ray spikes-by repeating the experiment with varying time delays between the pulses researchers can make a stop-motion movie of the tiny fast motions., Taking ghostly snapshots-Daniel Ratner and his coworkers want to apply the technique of ghost imaging., The secret is applying a method known as “ghost imaging” which reconstructs what objects look like without ever directly recording their images., X-ray free-electron lasers (XFELs)   

    From SLAC National Accelerator Lab: “Ghostly X-ray images could provide key info for analyzing X-ray laser experiments” 

    From SLAC National Accelerator Lab

    April 3, 2019
    Manuel Gnida

    1
    SLAC researchers suggest using the randomness of subsequent X-ray pulses from an X-ray laser to study the pulses’ interactions with matter, a method they call pump-probe ghost imaging. (Greg Stewart/SLAC National Accelerator Laboratory)

    X-ray free-electron lasers (XFELs) produce incredibly powerful beams of light that enable unprecedented studies of the ultrafast motions of atoms in matter. To interpret data taken with these extraordinary light sources, researchers need a solid understanding of how the X-ray pulses interact with matter and how those interactions affect measurements.

    Now, computer simulations by scientists from the Department of Energy’s SLAC National Accelerator Laboratory suggest that a new method could turn random fluctuations in the intensity of laser pulses from a nuisance into an advantage, facilitating studies of these fundamental interactions. The secret is applying a method known as “ghost imaging,” which reconstructs what objects look like without ever directly recording their images.

    “Instead of trying to make XFEL pulses less random, which is the approach we most often pursue for our experiments, we actually want to use randomness in this case,” said James Cryan from the Stanford PULSE Institute, a joint institute of Stanford University and SLAC. “Our results show that by doing so, we can get around some of the technical challenges associated with the current method for studying X-ray interactions with matter.”

    The research team published their results in Physical Review X.

    Taking advantage of X-ray spikes

    Scientists commonly look at these interactions through pump-probe experiments, in which they send pairs of X-ray pulses through a sample. The first pulse, called the pump pulse, rearranges how electrons are distributed in the sample. The second pulse, called the probe pulse, investigates the effects these rearrangements have on the motions of the sample’s electrons and atomic nuclei. By repeating the experiment with varying time delays between the pulses, researchers can make a stop-motion movie of the tiny, fast motions.

    One of the challenges is that X-ray lasers generate light pulses in a random process, so that each pulse is actually a train of narrow X-ray spikes whose intensities vary randomly between pulses.

    “Pump-probe experiments therefore typically require that we first prepare well-defined, short pulses that are less random,” said SLAC’s Daniel Ratner, the study’s lead author. “In addition we need to control the time delay between them very well.”

    In the new approach, he said, “We wouldn’t have to worry about any of that. We would use X-ray pulses as they come out of the XFEL without further modifications.”

    In fact, in this new way of thinking each pair of spikes within a single X-ray pulse can be considered a pair of pump and probe pulses, so researchers could do many pump-probe measurements with a single shot of the XFEL.

    2
    Simulated profile of an X-ray pulse from an X-ray free-electron laser. It consists of a train of narrow spikes whose intensity (power) fluctuates randomly. SLAC researchers suggest using pairs of these spikes for pump-probe experiments that trigger and measure structural changes in a sample, turning a former nuisance into an advantage. This example highlights three pairs of spikes with different time delays between them. (DOI: 10.1103/PhysRevX.9.01104 [N/A])

    Taking ghostly snapshots

    To produce snapshots of a sample’s molecular motions with this method, Ratner and his coworkers want to apply the technique of ghost imaging.

    In conventional imaging, light falling on an object produces a two-dimensional image on a detector – whether the back of your eye, the megapixel sensor in your cell phone or an advanced X-ray detector. Ghost imaging, on the other hand, constructs an image by analyzing how random patterns of light shining onto the object affect the total amount of light coming off the object.

    “In our method, the random patterns are the fluctuating spike structures of individual XFEL pulses,” said co-author Siqi Li, a graduate student at SLAC and Stanford and lead author of a previous study that demonstrated ghost imaging using electrons [Physical Review Letters]. “To do the image reconstruction, we need to repeat the experiment many times – about 100,000 times in our simulations. Each time, we measure the pulse profile with a diagnostic tool and analyze the signal emitted by the sample.”

    In a computational process that borrows ideas from machine learning, researchers can then turn these data into a visualization of the X-ray pulse’s effects on the sample.

    3
    In conventional imaging (left), light falling on an object produces a two-dimensional image on a detector. Ghost imaging (right) constructs an image by analyzing how random patterns of light shining onto the object affect the total amount of light coming off the object. (Greg Stewart/SLAC National Accelerator Laboratory)

    A complementary tool

    So far, the new idea has been tested only in simulations and awaits experimental validation, for instance at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, a DOE Office of Science user facility.

    SLAC LCLS

    Yet, the researchers are already convinced their method could complement conventional pump-probe experiments.

    “If future tests are successful, the method could strengthen our ability to look at very fundamental processes in XFEL experiments,” Ratner said. “It would also offer a few advantages that we would like to explore.” These include more stability, faster image reconstruction, less sample damage and the prospect of doing experiments at faster and faster timescales.

    Other co-authors of the paper are SLAC’s TJ Lane and Gennady Stupakov. The project was financially supported by the DOE Office of Science.

    See the full article here .


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    Please help promote STEM in your local schools.

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    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 10:57 am on February 9, 2019 Permalink | Reply
    Tags: , , , , Q-FARM will build upon Stanford and SLAC’s strong foundation in quantum science and engineering, QIS aims to harness the spookier properties of quantum mechanics: superposition-wave particle duality-entanglement, , , Quantum teleportation, SLAC National Accelerator Laboratory,   

    From Stanford University: “Q-FARM initiative to bolster quantum research at Stanford-SLAC 

    Stanford University Name
    From Stanford University

    February 8, 2019
    Ker Than

    1
    Patrick Hayden and Jelena Vuckovic will direct Stanford’s new Q-FARM initiative centered around experimental and theoretical quantum science and engineering. (Image credit: L.A. Cicero)

    There’s a new farm on the Farm.

    Stanford and SLAC National Accelerator Laboratory have launched a new Quantum Fundamentals, ARchitecture and Machines (Q-FARM) initiative to leverage and expand the university’s strengths in quantum science and engineering and to train the field’s next generation of scientists.

    “Our mission is not only to do research, it’s also to educate students, bring the community together, fill the gaps that we have in this space and connect to the world outside, both to industry and to other academic institutions,” said Q-FARM director Jelena Vuckovic, a professor of electrical engineering.

    Q-FARM emerged from Stanford’s long-range planning process as part of a team focused on understanding the natural world. The idea for it originated from faculty across departments who recognized that the university is uniquely positioned to become a leader in the field of quantum research, said Q-FARM deputy director Patrick Hayden, a professor of physics in the School of Humanities and Sciences.

    “I think it is very possible for Stanford to establish itself as the leading center in quantum science and engineering,” Hayden said. “We have advantages that other schools do not, including top-ranked science and engineering departments that are a short distance away from technology companies and SLAC, a renowned laboratory of the U.S. Department of Energy.”

    A second wave

    First formulated in the early 20th century, quantum mechanics deals with nature at its smallest scales. The theory describes with remarkable precision everything from the interactions between fundamental particles to the nature of chemical bonds and the electrical properties of materials. It even explains the origins of galaxies as tiny quantum ripples in spacetime that were stretched to enormous sizes during the first moments of the universe. Quantum mechanics is also the basis for some of our most transformative and ubiquitous technologies, including transistors and lasers.

    As influential as the theory has been, it’s poised to be even more impactful in the future. Beginning in the 1990s, quantum mechanics entered a “second wave” of discovery and innovation driven by theoretical and technological advances.

    On the theoretical front, quantum mechanics merged with computer science, mathematics and other branches of physics to give rise to a new field known as quantum information science (QIS). QIS aims to harness the spookier properties of quantum mechanics – superposition, wave-particle duality, entanglement – to manipulate information. Surprisingly, insights and techniques from QIS are proving useful not only for the design of quantum computers, algorithms and sensors but also for providing powerful new tools for investigating old questions in physics.

    “I finally feel, after all these years, that I’m at a stage in my life where things are as interesting as the things I missed because I came into physics too late,” said Leonard Susskind, a theoretical physicist at the Stanford Institute for Theoretical Physics. Susskind and Hayden are using quantum information to model black hole interiors and probe the nature of spacetime.

    As QIS has matured, so too has the ability of engineers to fabricate quantum-mechanical systems. Phenomena such as quantum teleportation that were once purely theoretical can now be created and studied in the lab. “This is what’s supposed to happen in science, that there is this feedback loop between theory and experiment, but it’s not always true,” Hayden said. “This is an area where it’s really happening and that’s very exciting.”

    A strong foundation

    Q-FARM will build upon Stanford and SLAC’s strong foundation in quantum science and engineering. The institutions include experts in the field, including Nobel laureate Robert Laughlin, and have played leading roles in a broad range of quantum research, including the discovery and characterization of new quantum materials, the use of quantum sensors to search for dark matter and exploration of the interface between QIS and fundamental physics.

    Furthermore, SLAC, as a multi-purpose DOE laboratory, brings unique facilities and expertise for QIS research that will complement Q-FARM on many fronts.

    Stanford and SLAC are also located in the heart of Silicon Valley, home to established companies like Google and to a long list of recent startups that are engaged in R&D efforts in quantum technologies. “Stanford has a history of strong interaction with Silicon Valley,” Hayden said. “All the big technology companies are investing in quantum computing. They are looking for the next major breakthrough in terms of computing power or communication power. Quantum mechanics seems to offer that.”

    Priorities

    With many world-leading research groups already established at Stanford, Q-FARM’s role will be to build bridges between them and create a community that can tackle the major emerging challenges in the area. Among Q-FARM’s initial priorities are the creation of postdoctoral and graduate fellowships and organizing research seminars where faculty, students and visiting scholars can present their research.

    Q-FARM will also focus on developing an educational program for undergraduate and graduate students to bolster the current curriculum. “We already have an excellent collection of classes, but we want to coordinate the program between physics and engineering so that we can better educate our students,” Vuckovic said.

    Demonstrating a united front on the research end will also help with faculty and student recruitment in an increasingly competitive field and attract some of the significant government funding that will target quantum research.

    In 2018, the U.S. Senate unanimously passed the National Quantum Initiative, which authorizes $1.275 billion to be spent over the next five years to fund American quantum information science research and to create multiple centers dedicated to quantum research and education.

    “Bringing one of those centers to Stanford and SLAC will help us maintain the strengths we already possess and establish ourselves more broadly in this field,” Vuckovic said.

    “If we can sustain this pace, Stanford will be the place where people who work in this field will want to be,” she added. “We have leading physics and leading engineering. We are in Silicon Valley. This is what makes us the right place to carry this forward.”

    See the full article here .


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