Tagged: SLAC Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 1:42 pm on February 21, 2018 Permalink | Reply
    Tags: , In a First Tiny Diamond Anvils Trigger Chemical Reactions by Squeezing, , SLAC   

    From SLAC: “In a First, Tiny Diamond Anvils Trigger Chemical Reactions by Squeezing” 


    SLAC Lab

    February 21, 2018
    Glennda Chui

    Press Office Contact:
    Andy Freeberg
    afreeberg@slac.stanford.edu
    (650) 926-4359

    Experiments with ‘molecular anvils’ mark an important advance for mechanochemistry, which has the potential to make chemistry greener and more precise.

    1
    An illustration shows complexes of soft molecules (yellow and pink) attached to “molecular anvils” (red and blue) that are about to be squeezed between two diamonds in a diamond anvil cell. The molecular anvils distribute this pressure unevenly, breaking bonds and triggering other chemical reactions in the softer molecules. (Peter Allen/UC-Santa Barbara)

    3
    A disassembled diamond anvil cell. Each half contains a tiny diamond housed in stainless steel. Samples are placed between the diamond tips; then the cell is closed and the tips squeezed together by tightening screws. This small device can generate pressures in the gigapascal range – 10,000 times the atmospheric pressure at the Earth’s surface. (Dawn Harmer/SLAC National Accelerator Laboratory)

    3
    An animation shows how attaching molecular anvils (gray cages) to softer molecules (red and yellow balls) distributes the pressure from a bigger diamond anvil unevenly, so chemical bonds bend and eventually break around the atom that bears the largest deformation (circled red ball). (Greg Stewart/SLAC National Accelerator Laboratory)

    Scientists have turned the smallest possible bits of diamond and other super-hard specks into “molecular anvils” that squeeze and twist molecules until chemical bonds break and atoms exchange electrons. These are the first such chemical reactions triggered by mechanical pressure alone, and researchers say the method offers a new way to do chemistry at the molecular level that is greener, more efficient and much more precise.

    The research was led by scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University, who reported their findings in Nature today.

    “Unlike other mechanical techniques, which basically pull molecules until they break apart, we show that pressure from molecular anvils can both break chemical bonds and trigger another type of reaction where electrons move from one atom to another,” said Hao Yan, a physical science research associate at SIMES, the Stanford Institute for Materials and Energy Sciences, and one of the lead authors of the study.

    “We can use molecular anvils to trigger changes at a specific point in a molecule while protecting the areas we don’t want to change,” he said, “and this creates a lot of new possibilities.”

    A reaction that’s mechanically driven has the potential to produce entirely different products from the same starting ingredients than one driven the conventional way by heat, light or electrical current, said study co-author Nicholas Melosh, a SIMES investigator and associate professor at SLAC and Stanford. It’s also much more energy efficient, and because it doesn’t need heat or solvents, it should be environmentally friendly.

    Putting the Squeeze on Materials with Diamonds

    The experiments were carried out with a diamond anvil cell about the size of an espresso cup in the laboratory of paper co-author Wendy Mao, an associate professor at SLAC and Stanford and an investigator with SIMES, which is a joint SLAC/Stanford institute.

    Diamond anvil cells squeeze materials between the flattened tips of two diamonds and can reach tremendous pressures – over 500 gigapascals, or about one and a half times the pressure at the center of the Earth. They’re used to explore what minerals deep inside the Earth are like and how materials under pressure develop unusual properties, among other things.

    These pressures are reached in a surprisingly straightforward way, by tightening screws to bring the diamonds closer together, Mao said. “Pressure is force per unit area, and we are compressing a tiny amount of sample between the tips of two small diamonds that each weigh only about a quarter of a carat,” she said, “so you only need a modest amount of force to reach high pressures.”

    Since the diamonds are transparent, light can go through them and reach the sample, said Yu Lin, a SIMES associate staff scientist who led the high-pressure part of the experiment.

    “We can use a lot of experimental techniques to study the reaction while the sample is compressed,” she said. “For instance, when we shine an X-ray beam into the sample, the sample responds by scattering or absorbing the light, which travels back through the diamond into a detector. Analyzing the signal from that light tells you if a reaction has occurred.”

    3
    Illustration of a diamond anvil cell, where samples can be compressed to very high pressures between the flattened tips of two diamonds. (Argonne National Laboratory, Greg Stewart/SLAC National Accelerator Laboratory)

    What usually happens when you squeeze a sample is that it deforms uniformly, with all the bonds between atoms shrinking by the same amount, Melosh said.

    Yet this is not always the case, he said: “If you compress a material that has both hard and soft components, such as carbon fibers embedded in epoxy, the bonds in the soft epoxy will deform a whole lot more than the ones in the carbon fiber.”

    They wondered if they could harness that same principle to bend or break specific bonds in an individual molecule.

    What got them thinking along those lines was a series of experiments Melosh’s team had done with diamondoids, the smallest possible bits of diamond, which are invisible to the naked eye and weigh less than a billionth of a billionth of a carat. Melosh co-directs a joint SLAC-Stanford program that isolates diamondoids from petroleum fluid and looks for ways to put them to use. In a recent study, his team had attached diamondoids to smaller, softer molecules to create Lego-like blocks that assembled themselves into the thinnest possible electrical wires, with a conducting core of sulfur and copper.

    Like carbon fibers in epoxy, these building blocks contained hard and soft parts. If put into a diamond anvil, would the hard parts act as mini-anvils that squeeze and deform the soft parts in a non-uniform way?

    The answer, they discovered, was yes.

    5
    A disassembled diamond anvil cell. Each half contains a tiny diamond housed in stainless steel. Samples are placed between the diamond tips; then the cell is closed and the tips squeezed together by tightening screws. This small device can generate pressures in the gigapascal range – 10,000 times the atmospheric pressure at the Earth’s surface. (Dawn Harmer/SLAC National Accelerator Laboratory)

    Tiny Anvils Open New Possibilities

    For their first experiments, they used copper sulfur clusters – tiny particles consisting of eight atoms – attached to molecular anvils made of another rigid molecule called carborane. They put this combination into the diamond anvil cell and cranked up the pressure.

    When the pressure got high enough, atomic bonds in the cluster broke, but that’s not all. Electrons moved from its sulfur atoms to its copper atoms and pure crystals of copper formed, which would not have occurred in conventional reactions driven by heat, the researchers said. They discovered a point of no return where this change becomes irreversible. Below that pressure point, the cluster goes back to its original state when pressure is removed.

    Computational studies revealed what had happened: Pressure from the diamond anvil cell moved the molecular anvils, and they in turn squeezed chemical bonds in the clusters, compressing them at least 10 times more than their own bonds had been compressed. This compression was also uneven, Yan said, and it bent or twisted some of the cluster’s bonds in a way that caused bonds to break, electrons to move and copper crystals to form.

    Other experiments, this time with diamondoids as molecular anvils, showed that small changes in the sizes and positions of the tiny anvils can make the difference between triggering a reaction or protecting part of a molecule so it doesn’t bend or react.

    The scientists were able to observe these changes with several techniques, including electron microscopy at Stanford and X-ray measurements at two DOE Office of Science user facilities – the Advanced Light Source at Lawrence Berkeley National Laboratory and the Advanced Photon Source at Argonne National Laboratory.

    LBNL/ALS

    ANL/APS

    6
    Researchers in a SIMES lab with equipment used in the molecular anvil study. From left: Hao Yan, a physical science research associate at SIMES; Nicholas Melosh, a SIMES investigator and associate professor at SLAC and Stanford; and Yu Lin, a SIMES associate staff scientist. (Dawn Harmer/SLAC National Accelerator Laboratory)

    “This is exciting, and it opens up a whole new field,” Mao said. “From our side, we’re interested in looking at how pressure can affect a wide range of technologically interesting materials, from superconductors that transmit electricity with no loss to halide perovskites, which have a lot of potential for next-generation solar cells. Once we understand what’s possible from a very basic science point of view we can think about the more practical side.”

    Going forward, the researchers also want to use this technique to look at reactions that are hard to do in conventional ways and see if compression makes them easier, Yan said.

    “If we want to dream big, could compression help us turn carbon dioxide from the air into fuel, or nitrogen from the air into fertilizer?” he said. “These are some of the questions that molecular anvils will allow people to explore.”

    In addition to SLAC, Stanford, Berkeley Lab and Argonne, researchers who contributed to this study came from the National Autonomous University of Mexico (UNAM), Justus-Liebig University in Germany, Hong Kong University of Science and Technology and the University of Chicago. Major funding came from the DOE Office of Science.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

    Advertisements
     
  • richardmitnick 2:28 pm on February 1, 2018 Permalink | Reply
    Tags: , , , , SLAC,   

    From SLAC: “Q&A: Alan Heirich and Elliott Slaughter Take On SLAC’s Big Data Challenges” 


    SLAC Lab

    January 9, 2018
    Manuel Gnida

    1
    Members of SLAC’s Computer Science Division. From left: Alex Aiken, Elliott Slaughter and Alan Heirich. (Dawn Harmer/SLAC National Accelerator Laboratory)

    As the Department of Energy’s SLAC National Accelerator Laboratory builds the next generation of powerful instruments for groundbreaking research in X-ray science, astronomy and other fields, its Computer Science Division is preparing for the onslaught of data these instruments will produce.

    The division’s initial focus is on LCLS-II, an upgrade to the Linac Coherent Light Source (LCLS) X-ray laser that will fire 8,000 times faster than the current version. LCLS-II promises to provide completely new views of the atomic world and its fundamental processes. However, the jump in firing rate goes hand and in hand with an explosion of scientific data that would overwhelm today’s computing architectures.

    SLAC/LCLS

    SLAC/LCLS II projected view

    In this Q&A, SLAC computer scientists Alan Heirich and Elliott Slaughter talk about their efforts to develop new computing capabilities that will help the lab cope with the coming data challenges.

    Heirich, who joined the lab last April, earned a PhD from the California Institute of Technology and has many years of experience working in industry and academia. Slaughter joined last June; he’s a recent PhD graduate from Stanford University, where he worked under the guidance of Alex Aiken, professor of computer science at Stanford and director of SLAC’s Computer Science Division.

    What are the computing challenges you’re trying to solve?

    Heirich: The major challenge we’re looking at now is that LCLS-II will produce so much more data than the current X-ray laser. Data rates will increase 10,000 times, from about 100 megabytes per second today to a terabyte per second in a few years. We need to think about the computing tools and infrastructure necessary to take control over that enormous future data stream.

    Slaughter: Our development of new computing architectures is aimed at analyzing LCLS-II data on the fly, providing initial results within a minute or two. This allows researchers to evaluate the quality of their data quickly, make adjustments and collect data in the most efficient way. However, real-time data analysis is quite challenging if you collect data with an X-ray laser that fires a million pulses per second.
    How can real-time analysis be achieved?

    Slaughter: We won’t be able to do all this with just the computing capabilities we have on site. The plan is to send some of the most challenging LCLS-II data analyses to the National Energy Research Scientific Computing Center (NERSC) at DOE’s Lawrence Berkeley National Laboratory, where extremely fast supercomputers will analyze the data and send the results back to us within minutes.

    Our team has joined forces with Amedeo Perazzo, who leads the LCLS Controls and Data Systems Division, to develop the system that will run the analysis. Scientists doing experiments at LCLS will be able to define the details of that analysis, depending on what their scientific questions are.

    Our goal is to be able to do the analysis in a very flexible way using all kinds of high-performance computers that have completely different hardware and architectures. In the future, these will also include exascale supercomputers that perform more than a billion billion calculations per second – up to a hundred times more than today’s most powerful machines.

    Is it difficult to build such a flexible computing system?

    Heirich: Yes. Supercomputers are very complex with millions of processors running in parallel, and we need to figure out how to make use of their individual architectures most efficiently. At Stanford, we’re therefore developing a programming system, called Legion, that allows people to write programs that are portable across very different high-performance computer architectures.

    Traditionally, if you want to run a program with the best possible performance on a new computer system, you may need to rewrite significant parts of the program so that it matches the new architecture. That’s very labor and cost intensive. Legion, on the other hand, is specifically designed to be used on diverse architectures and requires only relatively small tweaks when moving from one system to another. This approach prepares us for whatever the future of computing looks like. At SLAC, we’re now starting to adapt Legion to the needs of LCLS-II.

    We’re also looking into how we can visualize the scientific data after they are analyzed at NERSC.

    NERSC Cray XC40 Cori II supercomputer

    LBL NERSC Cray XC30 Edison supercomputer


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF


    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    The analysis will be done on thousands of processors, and it’s challenging to orchestrate this process and put it together into one coherent visual picture. We just presented one way to approach this problem at the supercomputing conference SC17 in November.

    What’s the goal for the coming year?

    Slaughter: We’re working with the LCLS team on building an initial data analysis prototype. One goal is to get a first test case running on the new system. This will be done with X-ray crystallography data from LCLS, which are used to reconstruct the 3-D atomic structure of important biomolecules, such as proteins. The new system will be much more responsive than the old one. It’ll be able to read and analyze data at the same time, whereas the old system can only do one or the other at any given moment.
    Will other research areas besides X-ray science profit from your work?

    Slaughter: Yes. Alex is working on growing our division, identifying potential projects across the lab and expanding our research portfolio. Although we’re concentrating on LCLS-II right now, we’re interested in joining other projects, such as the Large Synoptic Survey Telescope (LSST). SLAC is building the LSST camera, a 3.2-gigapixel digital camera that will capture unprecedented images of the night sky. But it will also produce enormous piles of data – millions of gigabytes per year. Progress in computer science is needed to efficiently handle these data volumes.

    Heirich: SLAC and its close partnership with Stanford Computer Science make for a great research environment. There is also a lot of interest in machine learning. In this form of artificial intelligence, computer programs get better and more efficient over time by learning from the tasks they performed in the past. It’s a very active research field that has seen a lot of growth over the past five years, and machine learning has become remarkably effective in solving complex problems that previously needed to be done by human beings.

    Many groups at SLAC and Stanford are exploring how they can exploit machine learning, including teams working in X-ray science, particle physics, astrophysics, accelerator research and more. But there are very fundamental computer science problems to solve. As machine learning replaces some conventional analysis methods, one big question is, for example, whether the solutions it generates are as reliable as those obtained in the conventional way.

    LCLS and NERSC are DOE Office of Science user facilities. Legion is being developed at Stanford with funding from DOE’s ExaCT Combustion Co-Design Center, Scientific Data Management, Analysis and Visualization program and Exascale Computing Project (ECP) as well as other contributions. SLAC’s Computer Science Division receives funding from the ECP.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 7:40 am on January 31, 2018 Permalink | Reply
    Tags: , Metal 3-D Printing, , SLAC,   

    From SLAC: “SLAC Scientists Investigate How Metal 3-D Printing Can Avoid Producing Flawed Parts” 


    SLAC Lab

    January 30, 2018
    Kimber Price

    1
    A metal 3-D printed sample the team used for experiments. (Johanna Nelson Weker/SLAC)


    Video – 3-D printing of a metal sample inside an X-ray chamber

    This video shows the 3-D printing of a metal sample inside an X-ray characterization chamber at Lawrence Livermore National Laboratory before the chamber was dismantled, transported to SLAC and rebuilt. At SLAC the glass windows were replaced with X-ray transparent beryllium windows. The chamber allows researchers to observe metal 3-D printing in real time. No video credit.


    This video shows the 3-D printing of a metal sample inside an X-ray characterization chamber at Lawrence Livermore National Laboratory before the chamber was dismantled, transported to SLAC and rebuilt. At SLAC the glass windows were replaced with X-ray transparent beryllium windows. The chamber allows researchers to observe metal 3-D printing in real time. No video credit.

    2
    SLAC staff scientist Johanna Nelson Weker, front, leads a study on metal 3-D printing at SLAC’s Stanford Synchrotron Radiation Lightsource with researchers Andrew Kiss and Nick Calta, back. (Dawn Harmer/SLAC).

    SLAC/SSRL

    Pits Among the Layers

    In metal 3-D printing, a thin layer of powdered metal, such as titanium alloys, steel, aluminum alloys, or copper, is distributed on a platform and selectively melted by a high-powered laser beam. Then the platform is lowered, a new layer of metal powder is applied and the process is repeated until the object is fully formed.

    This process often results in the formation of pits, or weak spots, when the metal cools and hardens unevenly while building up the layers. In the SLAC X-ray experiments, scientists are analyzing every aspect of the process ­– the kind of metal used, the level of heat from the laser, the speed at which the metal heats and cools – to find the best combination for eliminating pits, controlling the microstructure, and manufacturing strong metal parts.

    “We are providing the fundamental physics research that will help us identify which aspects of metal 3-D printing are important,” says Chris Tassone, a staff scientist in SSRL’s Materials Science Division. It’s practical information, he says, that could eventually lead to writing recipes for 3-D printer laser settings that manufacturers can use to produce sturdy parts.

    Diving in for a Better View

    Until recently, researchers watched from above as layers were being added to form a part. Because they couldn’t see below the surface of the metal, it was impossible to tell how deeply the laser was melting the layers as each one was applied. They tried imaging the growing layers with thermal radiation, or heat, but this did not give them enough information about what was causing the weak spots. X-rays, however, give researchers an excellent tool to see and record what’s happening inside the part as it’s being built.

    The scientists are using two X-ray methods to see what happens during metal 3-D printing. With one type of X-ray light, they create micron-resolution images of what happens as the layers of metal build up. The second method bounces X-rays off the atoms in the material to analyze its atomic structure as it changes from solid to liquid and back to solid form during the melting and cooling process.

    Thus far, the group has been looking at lasers hitting layers of metal powder, but they also plan to investigate another approach called “directed energy deposition.” In this process, a laser beam hits and melts metal powder or wire as it is being laid down, allowing creation of more complex geometric forms. This sort of 3-D printing is especially useful in making repairs.

    They also want to incorporate a high-speed camera into their experimental setup so they can collect photographs and video of the manufacturing process and correlate what they see with their X-ray data.

    This is important to manufacturers and other researchers who use cameras to observe the process but don’t have access to an X-ray synchrotron, Nelson Weker says: “We want people to be able to connect what they see on their cameras with what we are measuring here so they can infer what’s happening below the surface of the growing metal material. We want to put meaning to those signatures.”

    Other researchers on the metal 3-D printing project include Kevin Stone, Anthony Fong, Andrew Kiss and Vivek Thampy. SSRL is a DOE Office of Science user facility. The research was funded by the DOE Office of Energy Efficiency and Renewable Energy’s Advanced Manufacturing Office.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 2:06 pm on December 12, 2017 Permalink | Reply
    Tags: Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range, , Scientists Discover Path to Improving Game-Changing Battery Electrode, SLAC,   

    From SLAC: “Scientists Discover Path to Improving Game-Changing Battery Electrode” 


    SLAC Lab

    Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range. A new study opens a path to making them live up to their promise.

    1
    Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range. A new study opens a path to making them live up to their promise. (Stanford University/3Dgraphic)

    2
    SLAC and Stanford researchers at an SSRL beamline used for battery research. From left: SLAC staff scientists Apurva Mehta and Kevin Stone; Stanford graduate students Will Gent and Kipil Lim; and SLAC distinguished staff scientist Mike Toney. (Dawn Harmer/SLAC National Accelerator Laboratory)

    December 12, 2017
    If you add more lithium to the positive electrode of a lithium-ion battery – overstuff it, in a sense ­– it can store much more charge in the same amount of space, theoretically powering an electric car 30 to 50 percent farther between charges. But these lithium-rich cathodes quickly lose voltage, and years of research have not been able to pin down why – until now.

    After looking at the problem from many angles, researchers from Stanford University, two Department of Energy national labs and the battery manufacturer Samsung created a comprehensive picture of how the same chemical processes that give these cathodes their high capacity are also linked to changes in atomic structure that sap performance.

    “This is good news,” said William E. Gent, a Stanford University graduate student and Siebel Scholar who led the study. “It gives us a promising new pathway for optimizing the voltage performance of lithium-rich cathodes by controlling the way their atomic structure evolves as a battery charges and discharges.”

    Michael Toney, a distinguished staff scientist at SLAC National Accelerator Laboratory and a co-author of the paper, added, “It is a huge deal if you can get these lithium-rich electrodes to work because they would be one of the enablers for electric cars with a much longer range. There is enormous interest in the automotive community in developing ways to implement these, and understanding what the technological barriers are may help us solve the problems that are holding them back.”

    The team’s report appears today in Nature Communications.

    The researchers studied the cathodes with a variety of X-ray techniques at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) and Lawrence Berkeley National Laboratory’s Advanced Light Source (ALS).

    SLAC/SSRL

    LBNL/ALS

    Theorists from Berkeley Lab’s Molecular Foundry, led by David Prendergast, were also involved, helping the experimenters understand what to look for and explain their results.

    The cathodes themselves were made by Samsung Advanced Institute of Technology using commercially relevant processes, and assembled into batteries similar to those in electric vehicles.

    “This ensured that our results represented an understanding of a cutting-edge material that would be directly relevant for our industry partners,” Gent said. As an ALS doctoral fellow in residence, he was involved in both the experiments and the theoretical modelling for the study.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 7:48 pm on September 28, 2017 Permalink | Reply
    Tags: , , , SLAC, Stanford PULSE Institute   

    From SLAC: “A Potential New and Easy Way to Make Attosecond Laser Pulses: Focus a Laser on Ordinary Glass” 


    SLAC Lab

    September 28, 2017
    Glennda Chui

    1
    In this illustration, a near-infrared laser beam hits a piece of ordinary glass and triggers a process called high harmonic generation. It produces laser light pulses (top right) that are just billionths of a billionth of a second, or attoseconds, long, and the photons in those pulses are much higher energy than those in the original beam. The insets zoom in on how this happens. When the incoming laser light knocks electrons (e-) out of atoms in the glass, they fly away, loop back and reconnect with either their home atom (lower right) or a neighboring atom (upper left). These reconnections generate bright bursts of light, forming a “train” of attosecond pulses that leaves the glass and can be used to probe electron movements in solids. (Greg Stewart/SLAC National Accelerator Laboratory)

    This novel method could shrink the equipment needed to make laser pulses that are billionths of a billionth of a second long for studying ultra-speedy electron movements in solids, chemical reactions and future electronics.

    The discovery 30 years ago that laser light can be boosted to much higher energies and shorter pulses – just billionths of a billionth of a second, or attoseconds, long – is the basis of attosecond science, where researchers observe and try to control the movements of electrons. Electrons are key players in chemical reactions, biological processes, electronics, solar cells and other technologies, and only pulses this short can make snapshots of their incredibly swift moves.

    Now scientists from the Stanford PULSE Institute at the Department of Energy’s SLAC National Accelerator Laboratory have found a potential new way to make attosecond laser pulses using ordinary glass – in this case, the cover slip from a microscope slide.

    The discovery, reported in Nature Communications today, was a real surprise and opens new possibilities for attosecond science and technology, including the ability to probe ultra-speedy electron motions inside glasses and other solid materials. It could also dramatically shrink the size and cost of the setups needed to produce these tiny pulses, to the point where you might be able to generate pulses inside a fiber optic cable that delivers them to where they’re needed.

    “With today’s methods, you have to shine the laser beam through a special gas jet or through a crystal that has to be grown with great care at ultra-cold temperatures,” said Yong Sing You, a postdoctoral researcher at PULSE and lead author of the study. “But this is exciting because you can use everyday glass, which is cheap and easily available, at room temperature. If you were to put your eyeglasses into the experiment, it would still work, and it would not even damage the glasses.”

    2
    Postdoctoral researcher Yong Sing You, left, and staff scientist Shambhu Ghimire in the PULSE laser lab at SLAC where the experiments were carried out. (Chris Smith/SLAC National Accelerator Laboratory)

    A String of Surprises

    The process that generates attosecond laser pulses is called high harmonic generation, or HHG. Much like pressing on a guitar string produces a note that’s higher in pitch, shining laser light through certain materials changes the nature of the light, shifting it to higher energies and shorter pulses than a laser can reach on its own.

    Most of the time this is done in a gas. Incoming photons, or particles of light, from the laser hit atoms in the gas and liberate some of their electrons. The freed electrons fly away, loop back and reconnect with their home atoms. This reconnection generates attosecond bursts of light that combine to form an attosecond laser pulse.

    Starting in 2010, a series of experiments led by PULSE researchers Shambhu Ghimire and David Reis showed HHG can be produced in ways that were previously thought unlikely or even impossible: by beaming laser light into a crystal, frozen argon gas or an atomically thin semiconductor material.

    Unlike a gas, whose atoms are so far apart that you can think of them as behaving independently, atoms in a solid are so close together that scientists thought electrons freed by an incoming laser pulse would hit neighboring atoms, scatter and never return home to make that crucial reconnection. But it turned out this was not the case, Reis said: “There’s something about the orderly structure of the crystal that allows electrons to move throughout the lattice in a way that doesn’t dissipate their energy or give them a kick in some other direction. Even if they connect with a neighboring atom, they can still participate in HHG.”

    Fundamental Science with Practical Potential

    The fact that glass could generate HHG was also a surprise, said Ghimire, who helped lead the latest study. Because it’s amorphous, meaning that its silicon and oxygen atoms are arranged in no particular order, it did not seem like a good candidate.

    But glass’s random nature was just what the team needed to answer the fundamental scientific question at the heart of the study: How do the density and crystallinity of a material – the degree to which its atoms are arranged in an orderly lattice – independently affect its ability to produce HHG? A piece of glass and a quartz crystal are both made of silicon and oxygen, and they’re roughly the same density; only the arrangement of their atoms is different. So comparing the two should provide some answers.

    The scientists put the glass cover slip in their apparatus and hit it with pulses from their infrared laser beam.

    “You might think, again, that this wouldn’t work, because the electrons would bounce off their neighbors and never make it back home,” said Reis, who was not involved in the current paper. “But the surprising thing is that even in glass, if you hit the glass hard enough but not so hard that you break it, it works fine, although by a slightly different process.”

    The ability to produce HHG in glass and other solids is exciting, he said, because it has the potential to shrink the equipment needed to do this from the size of a lab bench to maybe just a few nanometers – billionths of a meter – in size.

    Ghimire added that producing harmonics in glass has potential technological applications. For instance, it produces the short wavelengths of laser light needed to design masks for patterning nanometer-scale features on semiconductor chips.

    “For this, they want as much intensity as possible, and also an easy way to deliver light to their samples,” he said. “Being able to produce short-wavelength laser light in normal glass would bring us a couple of steps closer to something they could actually use. We could even generate the short-wavelength light in the glass portion of optical fibers that then deliver it to wherever they wanted it.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 3:02 pm on August 30, 2017 Permalink | Reply
    Tags: Artificial Intelligence Analyzes Gravitational Lenses 10 Million Times Faster, , , , SLAC   

    From SLAC: “Artificial Intelligence Analyzes Gravitational Lenses 10 Million Times Faster” 


    SLAC Lab

    August 30, 2017
    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282
    Written by Manuel Gnida

    SLAC and Stanford researchers demonstrate that brain-mimicking ‘neural networks’ can revolutionize the way astrophysicists analyze their most complex data, including extreme distortions in spacetime that are crucial for our understanding of the universe.

    Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have for the first time shown that neural networks – a form of artificial intelligence – can accurately analyze the complex distortions in spacetime known as gravitational lenses 10 million times faster than traditional methods.

    Gravitational Lensing NASA/ESA

    “Analyses that typically take weeks to months to complete, that require the input of experts and that are computationally demanding, can be done by neural nets within a fraction of a second, in a fully automated way and, in principle, on a cell phone’s computer chip,” said postdoctoral fellow Laurence Perreault Levasseur, a co-author of a study published today in Nature.

    1
    KIPAC scientists have for the first time used artificial neural networks to analyze complex distortions in spacetime, called gravitational lenses, demonstrating that the method is 10 million times faster than traditional analyses. (Greg Stewart/SLAC National Accelerator Laboratory)

    Lightning Fast Complex Analysis

    The team at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of SLAC and Stanford, used neural networks to analyze images of strong gravitational lensing, where the image of a faraway galaxy is multiplied and distorted into rings and arcs by the gravity of a massive object, such as a galaxy cluster, that’s closer to us. The distortions provide important clues about how mass is distributed in space and how that distribution changes over time – properties linked to invisible dark matter that makes up 85 percent of all matter in the universe and to dark energy that’s accelerating the expansion of the universe.

    Until now this type of analysis has been a tedious process that involves comparing actual images of lenses with a large number of computer simulations of mathematical lensing models. This can take weeks to months for a single lens.

    But with the neural networks, the researchers were able to do the same analysis in a few seconds, which they demonstrated using real images from NASA’s Hubble Space Telescope and simulated ones.

    To train the neural networks in what to look for, the researchers showed them about half a million simulated images of gravitational lenses for about a day. Once trained, the networks were able to analyze new lenses almost instantaneously with a precision that was comparable to traditional analysis methods. In a separate paper, submitted to The Astrophysical Journal Letters, the team reports how these networks can also determine the uncertainties of their analyses.

    Prepared for Data Floods of the Future

    “The neural networks we tested – three publicly available neural nets and one that we developed ourselves – were able to determine the properties of each lens, including how its mass was distributed and how much it magnified the image of the background galaxy,” said the study’s lead author Yashar Hezaveh, a NASA Hubble postdoctoral fellow at KIPAC.

    This goes far beyond recent applications of neural networks in astrophysics, which were limited to solving classification problems, such as determining whether an image shows a gravitational lens or not.

    The ability to sift through large amounts of data and perform complex analyses very quickly and in a fully automated fashion could transform astrophysics in a way that is much needed for future sky surveys that will look deeper into the universe – and produce more data – than ever before.

    The Large Synoptic Survey Telescope (LSST), for example, whose 3.2-gigapixel camera is currently under construction at SLAC, will provide unparalleled views of the universe and is expected to increase the number of known strong gravitational lenses from a few hundred today to tens of thousands.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction 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.

    “We won’t have enough people to analyze all these data in a timely manner with the traditional methods,” Perreault Levasseur said. “Neural networks will help us identify interesting objects and analyze them quickly. This will give us more time to ask the right questions about the universe.”

    3
    KIPAC researchers used images of strongly lensed galaxies taken with the Hubble Space Telescope to test the performance of neural networks, which promise to speed up complex astrophysical analyses tremendously. (Yashar Hezaveh/Laurence Perreault Levasseur/Phil Marshall/Stanford/SLAC National Accelerator Laboratory; NASA/ESA)

    A Revolutionary Approach

    Neural networks are inspired by the architecture of the human brain, in which a dense network of neurons quickly processes and analyzes information.

    In the artificial version, the “neurons” are single computational units that are associated with the pixels of the image being analyzed. The neurons are organized into layers, up to hundreds of layers deep. Each layer searches for features in the image. Once the first layer has found a certain feature, it transmits the information to the next layer, which then searches for another feature within that feature, and so on.

    “The amazing thing is that neural networks learn by themselves what features to look for,” said KIPAC staff scientist Phil Marshall, a co-author of the paper. “This is comparable to the way small children learn to recognize objects. You don’t tell them exactly what a dog is; you just show them pictures of dogs.”

    But in this case, Hezaveh said, “It’s as if they not only picked photos of dogs from a pile of photos, but also returned information about the dogs’ weight, height and age.”

    3
    Scheme of an artificial neural network, with individual computational units organized into hundreds of layers. Each layer searches for certain features in the input image (at left). The last layer provides the result of the analysis. The researchers used particular kinds of neural networks, called convolutional neural networks, in which individual computational units (neurons, gray spheres) of each layer are also organized into 2-D slabs that bundle information about the original image into larger computational units. (Greg Stewart/SLAC National Accelerator Laboratory)

    Although the KIPAC scientists ran their tests on the Sherlock high-performance computing cluster at the Stanford Research Computing Center, they could have done their computations on a laptop or even on a cell phone, they said. In fact, one of the neural networks they tested was designed to work on iPhones.

    “Neural nets have been applied to astrophysical problems in the past with mixed outcomes,” said KIPAC faculty member Roger Blandford, who was not a co-author on the paper. “But new algorithms combined with modern graphics processing units, or GPUs, can produce extremely fast and reliable results, as the gravitational lens problem tackled in this paper dramatically demonstrates. There is considerable optimism that this will become the approach of choice for many more data processing and analysis problems in astrophysics and other fields.”

    Part of this work was funded by the DOE Office of Science.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 4:44 pm on July 26, 2017 Permalink | Reply
    Tags: , , SLAC, SLAC’s ultrafast 'electron camera' reveals unusual atomic motions that could be crucial for the efficiency of next-generation perovskite solar cells   

    From SLAC: “Atomic Movies May Help Explain Why Perovskite Solar Cells Are More Efficient” 


    SLAC Lab

    July 26, 2017
    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282

    SLAC’s ultrafast ‘electron camera’ reveals unusual atomic motions that could be crucial for the efficiency of next-generation perovskite solar cells.

    1
    According to a new SLAC study, atoms in perovskites respond to light with unusual rotational motions and distortions that could explain the high efficiency of these next-generation solar cell materials. (Greg Stewart/SLAC National Accelerator Laboratory.)

    In recent years, perovskites have taken the solar cell industry by storm. They are cheap, easy to produce and very flexible in their applications. Their efficiency at converting light into electricity has grown faster than that of any other material – from under four percent in 2009 to over 20 percent in 2017 – and some experts believe that perovskites could eventually outperform the most common solar cell material, silicon. But despite their popularity, researchers don’t know why perovskites are so efficient.

    Now experiments with a powerful “electron camera” at the Department of Energy’s SLAC National Accelerator Laboratory have discovered that light whirls atoms around in perovskites, potentially explaining the high efficiency of these next-generation solar cell materials and providing clues for making better ones.

    “We’ve taken a step toward solving the mystery,” said Aaron Lindenberg from the Stanford Institute for Materials and Energy Sciences (SIMES) and the Stanford PULSE Institute for ultrafast science, which are jointly operated by Stanford University and SLAC. “We recorded movies that show that certain atoms in a perovskite respond to light within trillionths of a second in a very unusual manner. This may facilitate the transport of electric charges through the material and boost its efficiency.”

    The study was published today in Science Advances.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 12:58 pm on July 19, 2017 Permalink | Reply
    Tags: , , New Droplet-on-Tape Method Assists Biochemical Research at X-Ray Lasers, SLAC, ,   

    From SLAC: “New Droplet-on-Tape Method Assists Biochemical Research at X-Ray Lasers” 


    SLAC Lab

    February 27, 2017 [Never saw this one before]

    1
    Acoustic droplet ejection allows scientists to deposit nanoliters of sample directly into the X-ray beam, considerably increasing the efficiency of sample consumption. A femtosecond pulse from an X-ray free-electron laser then intersects with a droplet that contains protein crystals. (SLAC National Accelerator Laboratory)

    SLAC/LCLS

    2
    As the drops move forward, they are hit with pulses of visible light or treated with oxygen gas, which triggers different chemical reactions depending on the sample studied. (SLAC National Accelerator Laboratory)

    Biological samples studied with intense X-rays at free-electron lasers are destroyed within nanoseconds after they are exposed. Because of this, the samples need to be continually refreshed to allow the many images needed for an experiment to be obtained. Conventional methods use jets that supply a continuous stream of samples, but this can be very wasteful as the X-rays only interact with a tiny fraction of the injected material.

    To help address this issue, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory, Brookhaven National Laboratory, and other institutes designed a new assembly-line system that rapidly replaces exposed samples by moving droplets along a miniature conveyor belt, timed to coincide with the arrival of the X-ray pulses.

    The droplet-on-tape system now allows the team to study the biochemical reactions in real-time from microseconds to seconds, revealing the stages of these complex reactions.

    In their approach, protein solution or crystals are precisely deposited in tiny liquid drops, made as ultrasound waves push the liquid onto a moving tape. As the drops move forward, they are hit with pulses of visible light or treated with oxygen gas, which triggers different chemical reactions depending on the sample studied. This allows the study of processes such as photosynthesis, which determines how plants absorb light from the sun and convert it into useable energy.

    Finally, powerful X-ray pulses from SLAC’s X-ray laser, the Linac Coherent Light Source (LCLS), probe the drops. In this study published in Nature Methods, the X-ray light scattered from the sample onto two different detectors simultaneously, one for X-ray crystallography and the other for X-ray emission spectroscopy. These are two complementary methods that provide information about the geometric and electronic structure of the catalytic sites of the proteins and allowed them to watch with atomic precision how the protein structures changed during the reaction.

    Below, see the conveyor belt in action at LCLS, a Department of Energy Office of Science User Facility.

    3
    Droplet-on-tape conveyor belt system delivers samples at the Linac Coherent Light Source (LCLS). (SLAC National Accelerator Laboratory)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 5:34 pm on July 5, 2017 Permalink | Reply
    Tags: , , , SLAC,   

    From SLAC: “SLAC’s Electron Hub Gets New ‘Metro Map’ for World’s Most Powerful X-Ray Laser” 


    SLAC Lab

    July 5, 2017
    Manuel Gnida

    1
    A reconfiguration of SLAC’s historic Beam Switch Yard will include electron transport lines needed for LCLS-II, a major upgrade to the Linac Coherent Light Source (LCLS) X-ray laser. (Greg Stewart/SLAC National Accelerator Laboratory)

    The central hub for powerful electron beams at the Department of Energy’s SLAC National Accelerator Laboratory is getting a makeover to prepare for the installation of LCLS-II – a major upgrade to the Linac Coherent Light Source (LCLS), the world’s first hard X-ray free-electron laser. LCLS-II will deliver the most powerful X-rays ever made in a lab, with beams that are 10,000 times brighter than before, opening up unprecedented research opportunities in chemistry, materials science, biology and energy research.

    2
    Central portion of the BSY before (left) and after the Reconfiguration Project. (Scott DeBarger/SLAC National Accelerator Laboratory)

    A Monumental Clean-up Operation

    To clear the path for LCLS-II, crews first had to remove all unnecessary materials from the BSY – a monumental task considering SLAC’s rich history in accelerator science and the legacy material it created.

    “When experiments end, most of the old equipment is typically left in place,” says SLAC’s Mark Woodley, an optics designer involved in the BSY Reconfiguration Project. “Only the things that are in the way of new experiments are taken out.”

    In its early days in the 1960s, the linac delivered electron beams to three experimental stations. There was one line going straight into the lab’s research yard. Today this line continues to the LCLS undulator. Pulsed magnets in the BSY could divert the beam into End Stations A and B via two beamlines that branched off the central line.

    In 1980, two more branches were added to feed electrons and positrons, the antiparticle siblings of electrons, into the two storage rings of the PEP accelerator (PEP-II from 1999). In 1987, another two branches were needed to deliver beams to the two arms of the Stanford Linear Collider (SLC).

    Most of the old materials left behind in the BSY by these experiments have now been cleared – a job that took 300 employees and subcontractors almost 24,000 hours of work in the period from December 2016 to May 2017. They removed 325 cubic yards, or about 24 tons, of material – enough to fill eight sea-land shipping containers – and more than 300,000 feet of cables.

    “Considering the monumental task we had ahead of us, it’s truly impressive how well this project went,” DeBarger says. “It involved many people from inside and outside the lab, and every single one of them was absolutely needed.”

    Building the Future of X-ray Science

    After clearing out the BSY, members of the Reconfiguration Project installed a new beamline that runs from the copper linac to the current LCLS undulator. In parallel, the system to extract electrons for the End Station A line was put in place by another project team.

    “We also installed the very first LCLS-II beam pipe at the end of a ‘muon shield’ that is constructed of 5- and 10-ton steel blocks and shields the beam transport hall downstream of the BSY, allowing access while beams are tuned in the BSY,” says Dean Hanquist, control account manager on Chan’s team.

    “In the end, we had to make sure that everything works properly again for LCLS, which has now resumed its experimental program,” says BSY Area Physicist Tonee Smith. “For example, all of the magnets used in the beamline to focus the electron beam and make small corrections to it were refurbished, and we had to remeasure and test them.”

    The remaining beamlines and junctions will be installed during a yearlong LCLS downtime, which will start in the summer of 2018. Once completed, the new BSY “metro system” will be ready to transport electron trains to the new X-ray laser facility, where they will power groundbreaking X-ray science for years to come.

    4
    Crew members gather at the conclusion of the BSY Reconfiguration Project. (Dawn Harmer/SLAC National Accelerator Laboratory)

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

    5
    The interior of the east portion of the Beam Switch Yard (BSY) showing three “tracks” that electrons accelerated in SLAC’s linear accelerator can be directed into. All of the beams for LCLS and LCLS-II are sent through the central tunnel. In early 2017, as part of the LCLS-II project, the steel Muon Shield was reconfigured to permit installation of a new beamline that will transport beams to a new Soft X-Ray Undulator. (Chris Smith/SLAC National Accelerator Laboratory)

    6
    Workers install the shield pipe that will position and protect the LCLS-II vacuum chamber within the Muon Shield. (Chris Smith/SLAC National Accelerator Laboratory)

    7
    Surveyors Bryan Rutledge and Francis Gaudreault measure the position of the LCLS beamline prior to its disassembly. (Chris Smith/SLAC National Accelerator Laboratory)

    8
    Mechanical Engineer Alev Ibrahimov, left, and Transport Systems CAM Dean Hanquist inspect the LCLS-II installation location in Sector 30. (Dawn Harmer/SLAC National Accelerator Laboratory)

    9
    Rigger Scot Johnson positions a movable hoist. (Chris Smith/SLAC National Accelerator Laboratory)

    10
    A crane removes the D-10 Tune-up Dump. This dump has five apertures, visible at the end of the device, which over the years allowed beams to head to various downstream experimental areas including LCLS, End Station A, End Station B and SPEAR. (Chris Smith/SLAC National Accelerator Laboratory)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.
    i1

     
  • richardmitnick 12:35 pm on June 17, 2017 Permalink | Reply
    Tags: , , , , , Helen Quinn and Roberto Peccei, Peccei-Quinn symmetry, , SLAC,   

    From Quanta: “Roberto Peccei and Helen Quinn, Driving Around Stanford in a Clunky Jeep” 

    Quanta Magazine
    Quanta Magazine

    June 15, 2017
    Thomas Lin
    Olena Shmahalo, Art Director
    Lucy Reading-Ikkanda, graphics

    1
    Ryan Schude for Quanta Magazine
    Helen Quinn and Roberto Peccei walking toward Stanford University’s new science and engineering quad. Behind them is the main quad, the oldest part of the campus. “If you look at a campus map,” said Quinn, who along with Peccei proposed Peccei-Quinn symmetry, “you will see the axis that goes through the middle of both quadrangle areas. We are on that line between the two.”

    Four decades ago, Helen Quinn and Roberto Peccei took on one of the great problems in theoretical particle physics: the strong charge-parity (CP) problem. Why does the symmetry between matter and antimatter break in weak interactions, which are responsible for nuclear decay, but not in strong interactions, which hold matter together?

    “The academic year 1976-77 was particularly exciting for me because Helen Quinn and Steven Weinberg were visiting the Stanford department of physics,” Peccei told Quanta in an email. “Helen and I had similar interests and we soon started working together.”

    Encouraged by Weinberg, who would go on to win a Nobel Prize in physics in 1979 for his work on the unification of electroweak interactions, Quinn and Peccei zeroed in on a CP-violating interaction whose strength can be characterized by an angular variable, theta. They knew theta had to be small, but no one had an elegant mechanism for explaining its smallness.

    “Steve liked to discuss physics over lunch, and Helen and I often joined him,” Peccei said. “Steve invariably brought up the theta problem in our lunch discussions, urging us to find a natural solution for why it was so small.”

    Quinn said by email that she and Peccei knew two things: The problem goes away if any quarks have zero mass (which seems to make theta irrelevant), and “in the very early hot universe all the quarks have zero mass.” They wondered how it could be that “theta is irrelevant in the early universe but matters once it cools enough that the quarks get their masses?”

    They proceeded to draft a “completely wrong paper based on conclusions we drew from this set of facts,” Quinn said. They went to Weinberg, whose comments helped clarify their thinking and, she said, “put us on the right track.”

    They realized they could naturally arrive at a zero value for theta by requiring a new symmetry, now known as the Peccei-Quinn mechanism. Besides being one of the popular proposed solutions to the strong CP problem, Peccei-Quinn symmetry also predicts the existence of a hypothetical “axion” particle, which has become a mainstay in theories of supersymmetry and cosmic inflation and has been proposed as a candidate for dark matter.

    2
    Peccei and Quinn discussing their proposed symmetry with the aid of a sombrero. Ryan Schude for Quanta Magazine

    That year at Stanford, Quinn and Peccei regularly interacted with the theory group at the Stanford Linear Accelerator Center (SLAC) as well as with another group from the University of California, Santa Cruz.

    “We formed a large and active group of theorists, which created a wonderful atmosphere of open discussion and collaboration,” Quinn said, adding that she recalls “riding with Roberto back and forth from Stanford to SLAC in his yellow and clunky Jeep, talking physics ideas as we went.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: