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  • richardmitnick 10:10 pm on April 16, 2014 Permalink | Reply
    Tags: , Laser Technology, , ,   

    From SLAC Lab: “Scientists Capture Ultrafast Snapshots of Light-driven Superconductivity” 

    April 16, 2014
    No Writer Credit

    A new study pins down a major factor behind the appearance of superconductivity – the ability to conduct electricity with 100 percent efficiency – in a promising copper-oxide material.

    Scientists used carefully timed pairs of laser pulses at SLAC National Accelerator Laboratory’s Linac Coherent Light Source (LCLS) to trigger superconductivity in the material and immediately take X-ray snapshots of its atomic and electronic behavior as superconductivity emerged.

    und
    The Undulator Hall at SLAC’s Linac Coherent Light Source X-ray laser. (Brad Plummer/SLAC)

    They discovered that so-called “charge stripes” of increased electrical charge melted away as superconductivity appeared. Further, the results help rule out the theory that shifts in the material’s atomic lattice hinder the onset of superconductivity.

    Armed with this new understanding, scientists may be able to develop new techniques to eliminate these charge stripes and help pave the way for room-temperature superconductivity, often considered the holy grail of condensed matter physics. The demonstrated ability to rapidly switch between the insulating and superconducting states could also prove useful in advanced electronics and computation.

    The results, from a collaboration led by scientists from the Max Planck Institute for the Structure and Dynamics of Matter in Germany and the U.S. Department of Energy’s SLAC and Brookhaven national laboratories, were published online April 16, 2014, in the journal Physical Review Letters.

    “The very short timescales and the need for high spatial resolution made this experiment extraordinarily challenging,” said co-author Michael Först, a scientist at the Max Planck Institute. “Now, using femtosecond X-ray pulses, we found a way to capture the quadrillionths-of-a-second dynamics of the charges and the crystal lattice. We’ve broken new ground in understanding light-induced superconductivity.”

    Josh Turner, an LCLS staff scientist, said, “This represents a very important result in the field of superconductivity using LCLS. It demonstrates how we can unravel different types of complex mechanisms in superconductivity that have, up until now, been inseparable.”

    He added, “To make this measurement, we had to push the limits of our current capabilities. We had to measure a very weak, barely detectable signal with state-of-the-art detectors, and we had to tune the number of X-rays in each laser pulse to see the signal from the stripes without destroying the sample.”

    Ripples in Quantum Sand

    The compound used in this study was a layered material consisting of lanthanum, barium, copper, and oxygen grown at Brookhaven Lab by physicist Genda Gu. Each copper oxide layer contained the crucial charge stripes.

    man
    Physicist Genda Gu in the Brookhaven Lab facility where the copper-oxide materials were grown for this study.

    “Imagine these stripes as ripples frozen in the sand,” said John Hill, a Brookhaven Lab physicist and coauthor on the study. “Each layer has all the ripples going in one direction, but in the neighboring layers they run crosswise. From above, this looks like strings in a pile of tennis racquets. We believe that this pattern prevents each layer from talking to the next, thus frustrating superconductivity.”

    To excite the material and push it into the superconducting phase, the scientists used mid-infrared laser pulses to “melt” those frozen ripples. These pulses had previously been shown to induce superconductivity in a related compound at a frigid 10 Kelvin (minus 442 degrees Fahrenheit).

    “The charge stripes disappeared immediately,” Hill said. “But specific distortions in the crystal lattice, which had been thought to stabilize these stripes, lingered much longer. This shows that only the charge stripes inhibit superconductivity.”

    Stroboscopic Snapshots

    To capture these stripes in action, the collaboration turned to SLAC’s LCLS X-ray laser, which works like a camera with a shutter speed faster than 100 femtoseconds, or quadrillionths of a second, and provides atomic-scale image resolution. LCLS uses a section of SLAC’s 2-mile-long linear accelerator to generate the electrons that give off X-ray light.

    Researchers used the so-called “pump-probe” approach: an optical laser pulse strikes and excites (pumps) the lattice and an ultrabright X-ray laser pulse is carefully synchronized to follow within femtoseconds and measure (probe) the lattice and stripe configurations. Each round of tests results in some 20,000 X-ray snapshots of the changing lattice and charge stripes, a bit like a strobe light rapidly illuminating the process.

    To measure the changes with high spatial resolution, the team used a technique called resonant soft X-ray diffraction. The LCLS X-rays strike and scatter off the crystal into the detector, carrying time-stamped signatures of the material’s charge and lattice structure that the physicists then used to reconstruct the rise and fall of superconducting conditions.

    “By carefully choosing a very particular X-ray energy, we are able to emphasize the scattering from the charge stripes,” said Brookhaven Lab physicist Stuart Wilkins, another co-author on the study. “This allows us to single out a very weak signal from the background.”

    Toward Superior Superconductors

    The X-ray scattering measurements revealed that the lattice distortion persists for more than 10 picoseconds (trillionths of a second) – long after the charge stripes melted and superconductivity appeared, which happened in less than 400 femtoseconds. Slight as it may sound, those extra trillionths of a second make a huge difference.

    “The findings suggest that the relatively weak and long-lasting lattice shifts do not play an essential role in the presence of superconductivity,” Hill said. “We can now narrow our focus on the stripes to further pin down the underlying mechanism and potentially engineer superior materials.”

    Andrea Cavalleri, director of the Max Planck Institute, said, “Light-induced superconductivity was only recently discovered, and we’re already seeing fascinating implications for understanding it and going to higher temperatures. In fact, we have observed the signature of light-induced superconductivity in materials all the way up to 300 Kelvin (80 degrees Fahrenheit) – that’s really a significant breakthrough that warrants much deeper investigations.”

    Other collaborators on this research include the University of Groningen, the University of Oxford, Diamond Light Source, the Lawrence Berkeley National Laboratory, Stanford University, the European XFEL, the University of Hamburg and the Center for Free-Electron Laser Science.

    The research conducted at the Soft X-ray Materials Science (SXR) experimental station at SLAC’s LCLS – a DOE Office of Science user facility – was funded by Stanford University, Lawrence Berkeley National Laboratory, the University of Hamburg and the Center for Free-Electron Laser Science (CFEL). Work performed at Brookhaven Lab was supported by the DOE’s Office of Science.

    See the full article here.

    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.
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  • richardmitnick 1:11 pm on March 31, 2014 Permalink | Reply
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    From Ames Lab: “Ultra-fast laser spectroscopy lights way to understanding new materials” 

    AmesLabII
    Ames Laboratory

    Feb. 28, 2014
    Jigang Wang, Material Sciences and Engineering, 515-294-5630
    Breehan Gerleman Lucchesi, Public Affairs, 515-294-9750

    Scientists at the U.S. Department of Energy’s Ames Laboratory are revealing the mysteries of new materials using ultra-fast laser spectroscopy, similar to high-speed photography where many quick images reveal subtle movements and changes inside the materials. Seeing these dynamics is one emerging strategy to better understanding how new materials work, so that we can use them to enable new energy technologies.

    Physicist Jigang Wang and his colleagues recently used ultra-fast laser spectroscopy to examine and explain the mysterious electronic properties of iron-based superconductors. Results appeared in Nature Communications this month.

    Superconductors are materials that, when cooled below a certain temperature, display zero electrical resistance, a property that could someday make possible lossless electrical distribution. Superconductors start in a “normal” often magnetic state and then transition to a superconducting state when they are cooled to a certain temperature.

    What is still a mystery is what goes on in materials as they transform from normal to superconducting. And this “messy middle” area of superconducting materials’ behavior holds richer information about the why and how of superconductivity than do the stable areas.

    fast
    Ames Laboratory scientists use ultra-fast laser spectroscopy to “see” tiny actions in real time in
    materials. Scientists apply a pulse laser to a sample to excite the material. Some of the laser light
    is absorbed by the material, but the light that passes through or reflected from the material can be
    used to take super-fast “snapshots” of what is going on in the material following the laser pulse.

    “The stable states of materials aren’t quite as interesting as the crossover region when comes to understanding materials’ mechanisms because everything is settled and there’s not a lot of action. But, in this crossover region to superconductivity, we can study the dynamics, see what goes where and when, and this information will tell us a lot about the interplay between superconductivity and magnetism,” said Wang, who is also an associate professor of physics and astronomy at Iowa State University.

    But the challenges is that in the crossover region, all the different sets of materials properties that scientists examine, like its magnetic order and electronic order, are all coupled. In other words, when there’s a change to one set of properties, it changes all the others. So, it’s really difficult to trace what individual changes and properties are dominant.

    The complexity of this coupled state has been studied by groundbreaking work by research groups at Ames Laboratory over the past five years. Paul Canfield, an Ames Laboratory scientist and expert in designing and developing iron-based superconductor materials, created and characterized a very high quality single crystal used in this investigation. These high-quality single crystals had been exceptionally well characterized by other techniques and were essentially “waiting for their close up” under Wang’s ultra-fast spot-light.

    Wang and the team used ultra-fast laser spectroscopy to “see” the tiny actions in materials. In ultra-fast laser spectroscopy, scientists apply a pulsed laser to a materials sample to excite particles within the sample. Some of the laser light is absorbed by the material, but the light that passes through the material can be used to take super-fast “snapshots” of what is going on in the material following the laser pulse and then replayed afterward like a stop-action movie.

    The technique is especially well suited to understanding the crossover region of iron-arsenide based superconductors materials because the laser excitation alters the material so that different properties of the material are distinguishable from each other in time, even the most subtle evolutions in the materials’ properties.

    “Ultra-fast laser spectroscopy is a new experimental tool to study dynamic, emergent behavior in complex materials such as these iron-based superconductors,” said Wang. “Specifically, we answered the pressing question of whether an electronically-driven nematic order exists as an independent phase in iron-based superconductors, as these materials go from a magnetic normal state to superconducting state. The answer is yes. This is important to our overall understanding of how superconductors emerge in this type of materials.”

    Aaron Patz and Tianqi Li collaborated on the laser spectroscopy work. Sheng Ran, Sergey L. Bud’ko and Paul Canfield collaborated on sample development at Ames Laboratory and Iowa State University. Rafael M. Fernandes at the University of Minnesota, Joerg Schmalian, formerly of Ames Laboratory and now at Karlsruhe Institute of Technology and Ilias E. Perakis at University of Crete, Greece collaborated on the simulation work.

    Wang, Patz, Li, Ran, Bud’ko and Canfield’s work at Ames Laboratory was supported by the U.S. Department of Energy’s Office of Science, (sample preparation and characterization). Wang’s work on pnictide superconductors is supported by Ames Laboratory’s Laboratory Directed Research and Development (LDRD) funding (femtosecond laser spectroscopy).

    DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

    See the full article here.

    Ames Laboratory is a government-owned, contractor-operated research facility of the U.S. Department of Energy that is run by Iowa State University.

    For more than 60 years, the Ames Laboratory has sought solutions to energy-related problems through the exploration of chemical, engineering, materials, mathematical and physical sciences. Established in the 1940s with the successful development of the most efficient process to produce high-quality uranium metal for atomic energy, the Lab now pursues a broad range of scientific priorities.

    Ames Laboratory shares a close working relationship with Iowa State University’s Institute for Physical Research and Technology, or IPRT, a network of scientific research centers at Iowa State University, Ames, Iowa.

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  • richardmitnick 3:30 pm on March 25, 2014 Permalink | Reply
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    From SLAC Lab: “A New Way to Tune X-ray Laser Pulses” 

    [New policies at SLAC are resulting in my bringing the lab's news later than necessary. SLAC is working on improving the situation.]

    March 10, 2014
    Glenn Roberts Jr.

    A new system at SLAC National Accelerator Laboratory’s X-ray laser narrows a rainbow spectrum of X-ray colors to a more intense band of light, creating a much more powerful way to view fine details in samples at the scale of atoms and molecules.

    “It’s like going from regular television to HDTV,” said Norbert Holtkamp, SLAC deputy director and leader of the lab’s Accelerator Directorate.

    Designed and installed at SLAC’s Linac Coherent Light Source (LCLS) in collaboration with Lawrence Berkeley National Laboratory and Switzerland’s Paul Scherrer Institute, it is the world’s first “self-seeding” system for enhancing lower-energy or “soft” X-rays.

    Scientists had to overcome a series of engineering challenges to build it, and it is already drawing international interest for its potential use at other X-ray free-electron lasers.

    “Because this system delivers more intense soft X-ray light at the precise energy we want for experiments, we can make measurements at a far faster rate,” said Bill Schlotter, an LCLS staff scientist. “It will open new possibilities, from exploring exotic materials and biological and chemical samples in greater detail to improving our view of the behavior of atoms and molecules.”

    Cutting Through the Noise

    LCLS’s laser pulses vary in intensity and color, and this randomness or “noise,” like fuzzy reception on a TV, sometimes complicates experiments and data analysis. Self-seeding cuts through this noise by providing a stronger and more consistent intensity peak within each laser pulse.

    “We’re taking something that’s in a range of colors and trying to select a single color and pack as much power in as we can,” said Daniel Ratner, an associate staff scientist at SLAC and lead scientist on the project. “We’re going from the randomness of a typical pulse to a nice, clean, narrow profile that is well-understood.”

    Scientists had installed another self-seeding system at LCLS in 2012 for higher-energy “hard” X-rays. It has been put to use in studies of matter under extreme temperatures and pressures, the structure of biological molecules and electron motions in materials, for example.

    Extending self-seeding to soft X-rays was a logical next step. LCLS scientists Yiping Feng, Daniele Cocco and others designed a compact X-ray optics system that was key to the success of the project, which was led by SLAC’s Jerry Hastings and Zhirong Huang.

    The team achieved self-seeding with soft X-rays in December, and conducted follow-up tests in January and February. They are working to improve the system and to make it available to visiting scientists.

    LCLS X-ray pulses are powered by an electron beam from SLAC’s linear accelerator. The electrons wiggle through a series of powerful magnets, called undulators. This forces them to emit X-ray light, and that light grows in intensity as it moves through the undulator chain.

    SLAC Linear Accelerator
    SLAC Linear Accelerator

    The new system, installed about a quarter of the way down the undulator chain, diverts a narrow, purified slice of the X-ray laser light and briefly and precisely overlaps it with the beam of electrons traveling through the undulators. This produces a “seed” – a spike of high-intensity light in a single color – that is amplified as the X-ray pulses move through the remaining undulators toward LCLS experimental stations.

    Engineering Challenge

    “A big technical challenge was to fit everything in one 13-foot-long undulator section,” including a complex network of cabling, optics, magnets and mechanical systems, said SLAC’s Paul Montanez, project manager and lead engineer for the system. “A tremendous number of people pulled this project together, from administrative, technical and professional staff to scientists.”

    feeder
    A view of the soft X-ray self-seeding system during installation in the Undulator Hall at SLAC’s Linac Coherent Light Source X-ray laser. (Brad Plummer/SLAC)

    man
    Ziga Oven monitors the installation of the soft X-ray self-seeding system in the Undulator Hall at SLAC’s Linac Coherent Light Source X-ray laser. (Brad Plummer/SLAC)

    The Berkeley Lab team designed and built the hardware that diverts and refines the X-ray light, as well as mechanical systems that align the X-rays and electrons, adjust the X-ray energy and retract components out of the path of X-rays when not in use. The Paul Scherrer team designed and built the optical equipment for the system. SLAC was responsible for integrating the components and building the controls that automate the system.

    “This project was pretty challenging in that we were designing and developing and installing this equipment in an operating facility, with little time for the actual installation,” said Ken Chow, the lead engineer for the Berkeley Lab effort. He noted that the project required many custom parts, such as a movable mirror that must rotate with incredible precision – “It’s like taking a meter stick and moving one end one-half millionth of a meter,” he said.

    Next Steps

    SLAC scientists are hoping to use the seeding system, coupled with an intricate tuning of the magnets in the undulators, to produce even higher-intensity pulses for the next generation of X-ray lasers.

    Already, collaborators from the Paul Scherrer Institute are considering a similar self-seeding system for a planned soft X-ray laser in Switzerland, and there has been great interest in such a system for other X-ray laser projects in the works.

    “We would like to learn and profit from this for our own project, the SwissFEL,” said Uwe Flechsig, who led the Paul Scherrer team that was responsible for delivering the system’s optics.

    See the full article here.

    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.
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  • richardmitnick 2:49 pm on February 20, 2014 Permalink | Reply
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    From Caltech: “A New Laser for a Faster Internet” 

    Caltech Logo
    Caltech

    02/19/2014
    Jessica Stoller-Conrad

    A new laser developed by a research group at Caltech holds the potential to increase by orders of magnitude the rate of data transmission in the optical-fiber network—the backbone of the Internet.

    The study was published the week of February 10–14 in the online edition of the Proceedings of the National Academy of Sciences. The work is the result of a five-year effort by researchers in the laboratory of Amnon Yariv, Martin and Eileen Summerfield Professor of Applied Physics and professor of electrical engineering; the project was led by postdoctoral scholar Christos Santis (PhD ’13) and graduate student Scott Steger.Light is capable of carrying vast amounts of information—approximately 10,000 times more bandwidth than microwaves, the earlier carrier of long-distance communications. But to utilize this potential, the laser light needs to be as spectrally pure—as close to a single frequency—as possible. The purer the tone, the more information it can carry, and for decades researchers have been trying to develop a laser that comes as close as possible to emitting just one frequency.

    laser
    No image Credit

    Today’s worldwide optical-fiber network is still powered by a laser known as the distributed-feedback semiconductor (S-DFB) laser, developed in the mid 1970s in Yariv’s research group. The S-DFB laser’s unusual longevity in optical communications stemmed from its, at the time, unparalleled spectral purity—the degree to which the light emitted matched a single frequency. The laser’s increased spectral purity directly translated into a larger information bandwidth of the laser beam and longer possible transmission distances in the optical fiber—with the result that more information could be carried farther and faster than ever before.

    At the time, this unprecedented spectral purity was a direct consequence of the incorporation of a nanoscale corrugation within the multilayered structure of the laser. The washboard-like surface acted as a sort of internal filter, discriminating against spurious “noisy” waves contaminating the ideal wave frequency. Although the old S-DFB laser had a successful 40-year run in optical communications—and was cited as the main reason for Yariv receiving the 2010 National Medal of Science—the spectral purity, or coherence, of the laser no longer satisfies the ever-increasing demand for bandwidth.

    “What became the prime motivator for our project was that the present-day laser designs—even our S-DFB laser—have an internal architecture which is unfavorable for high spectral-purity operation. This is because they allow a large and theoretically unavoidable optical noise to comingle with the coherent laser and thus degrade its spectral purity,” he says.

    The old S-DFB laser consists of continuous crystalline layers of materials called III-V semiconductors—typically gallium arsenide and indium phosphide—that convert into light the applied electrical current flowing through the structure. Once generated, the light is stored within the same material. Since III-V semiconductors are also strong light absorbers—and this absorption leads to a degradation of spectral purity—the researchers sought a different solution for the new laser.

    The high-coherence new laser still converts current to light using the III-V material, but in a fundamental departure from the S-DFB laser, it stores the light in a layer of silicon, which does not absorb light. Spatial patterning of this silicon layer—a variant of the corrugated surface of the S-DFB laser—causes the silicon to act as a light concentrator, pulling the newly generated light away from the light-absorbing III-V material and into the near absorption-free silicon.

    This newly achieved high spectral purity—a 20 times narrower range of frequencies than possible with the S-DFB laser—could be especially important for the future of fiber-optic communications. Originally, laser beams in optic fibers carried information in pulses of light; data signals were impressed on the beam by rapidly turning the laser on and off, and the resulting light pulses were carried through the optic fibers. However, to meet the increasing demand for bandwidth, communications system engineers are now adopting a new method of impressing the data on laser beams that no longer requires this “on-off” technique. This method is called coherent phase communication.

    In coherent phase communications, the data resides in small delays in the arrival time of the waves; the delays—a tiny fraction (10-16) of a second in duration—can then accurately relay the information even over thousands of miles. The digital electronic bits carrying video, data, or other information are converted at the laser into these small delays in the otherwise rock-steady light wave. But the number of possible delays, and thus the data-carrying capacity of the channel, is fundamentally limited by the degree of spectral purity of the laser beam. This purity can never be absolute—a limitation of the laws of physics—but with the new laser, Yariv and his team have tried to come as close to absolute purity as is possible.

    These findings were published in a paper titled, High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms. In addition to Yariv, Santis, and Steger, other Caltech coauthors include graduate student Yaakov Vilenchik, and former graduate student Arseny Vasilyev (PhD, ’13). The work was funded by the Army Research Office, the National Science Foundation, and the Defense Advanced Research Projects Agency. The lasers were fabricated at the Kavli Nanoscience Institute at Caltech.

    See the full article here.

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 9:31 am on December 17, 2013 Permalink | Reply
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    From Livermore Lab: “Lawrence Livermore researchers demonstrate high-energy betatron X-rays” 


    Lawrence Livermore National Laboratory

    12/17/2013
    Breanna Bishop, LLNL, (925) 423-9802, bishop33@llnl.gov

    A Lawrence Livermore team, along with researchers from the University of California at Los Angeles and SLAC National Accelerator Laboratory, has recently produced some of the highest energy betatron X-rays ever demonstrated, with the added benefit of being produced on a system the size of a large tabletop.

    tabletop
    LLNL researchers Felicie Albert (center) and Bradley Pollock (far right) prepare the Callisto laser system and setup for betatron X-ray experiments at the Laboratory’s Jupiter Laser Facility.

    callisto
    Callisto

    Betatron X-ray radiation, produced when relativistic electrons are accelerated and oscillate in a laser-driven plasma channel (during a process known as laser-wakefield acceleration), is an X-ray source holding great promise for future high energy density (HED) science experiments. X-rays produced in this manner are femtosecond in duration, directional, spatially coherent and broadband, making them highly attractive as a probe.

    “This source could someday be an alternative to X-ray synchrotrons and free electron lasers. These machines are expensive, complex, and kilometers in length,” said lead author Felicie Albert. “As a result, few of these exist worldwide, and their size prevents their use as mobile systems or as diagnostic tools in conjunction with other large-scale HED drivers, such as the National Ignition Facility.”

    The experiments were performed at LLNL’s Jupiter Laser Facility, using the 200-Terawatt Callisto laser system. By focusing Callisto’s 60 femtosecond laser pulse onto a gas cell filled with helium, the researchers produced up to 80 kiloelectronvolts of betatron X-rays and measured for the first time the angular dependence of betatron X-ray spectra in a laser-wakefield accelerator.

    “We hope to use this remarkable X-ray tool to explore the properties of high energy density plasmas at femtosecond resolution and at the atomic level, which are poorly understood at present,” Albert said. “Many applications beckon on the horizon, as these X-rays could be used in any research involving X-ray synchrotron or free electron laser radiation. It could be used to discover new physical properties of materials at the high pressures and temperatures found only in planet interiors and fusion plasmas.”

    Albert was joined by LLNL’s Bradley Pollock, Joseph Ralph, Yu-Hsin Chen, David Alessi and Arthur Pak and collaborators from the UCLA Department of Electrical Engineering and the SLAC National Accelerator Laboratory. This work, supported by the LLNL Laboratory Directed Research and Development program, was reported in the Dec. 6 issue of Physical Review Letters.

    See the full article here.

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  • richardmitnick 1:51 pm on September 30, 2013 Permalink | Reply
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    From SLAC: “Researchers Demonstrate ‘Accelerator on a Chip’” 

    September 27, 2013

    In an advance that could dramatically shrink particle accelerators for science and medicine, researchers used a laser to accelerate electrons at a rate 10 times higher than conventional technology in a nanostructured glass chip smaller than a grain of rice.

    chip
    Nanofabricated chips of fused silica just 3 millimeters long were used to accelerate electrons at a rate 10 times higher than conventional particle accelerator technology. (Brad Plummer/SLAC)

    The achievement was reported today in Nature by a team including scientists from the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory and Stanford University.

    “We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces,” said Joel England, the SLAC physicist who led the experiments. “It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science.”

    Because it employs commercial lasers and low-cost, mass-production techniques, the researchers believe it will set the stage for new generations of “tabletop” accelerators.

    At its full potential, the new “accelerator on a chip” could match the accelerating power of SLAC’s 2-mile-long linear accelerator in just 100 feet, and deliver a million more electron pulses per second.

    See the full article here.

    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.
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  • richardmitnick 3:39 pm on September 17, 2013 Permalink | Reply
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    From Livermore Lab: “Lawrence Livermore to build advanced laser system in Czech Republic” 


    Lawrence Livermore National Laboratory

    09/17/2013
    Breanna Bishop, LLNL, (925) 423-9802, bishop33@llnl.gov

    Lawrence Livermore National Laboratory (LLNL), through Lawrence Livermore National Security LLC (LLNS), has been awarded more than $45 million to develop and deliver a state-of-the-art laser system for the European Union’s Extreme Light Infrastructure Beamlines facility (ELI-Beamlines), under construction in DolnÃ- Brezany near Prague in the Czech Republic.

    Funds were received today, allowing the project to begin immediately. The agreement will deliver a laser system with performance far more advanced than current laser systems in the world. This will allow the ELI-Beamlines facility to undertake unprecedented research in areas as diverse as medical imaging, particle acceleration, homeland security and quantum physics, opening up applications in many areas of industry as well as cutting-edge academic research.

    rend
    Artist renderings of the ELI Beamlines facility, currently under construction in the Czech Republic.

    man
    A CAD image of the ELI-HAPLS laser

    LLNL was chosen as the single preferred supplier as a result of its expertise in the research, development and engineering of sophisticated laser systems. This capability is the result of sustained investment in this area by the United States Department of Energy for the Laboratory’s national security missions.

    Researchers from LLNL’s NIF & Photon Science Directorate will work with scientists from the Czech Institute of Physics to design, develop, assemble and test the system at LLNL. After completion of qualification testing, the HAPLS will be transported to the ELI Beamlines facility in 2016, where it will be commissioned for use by the international scientific community.

    See the full article here.

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  • richardmitnick 4:24 am on August 13, 2013 Permalink | Reply
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    From Livermore Lab: “D2T3 to join the ranks at National Ignition Facility” 


    Lawrence Livermore National Laboratory

    08/07/2013
    Breanna Bishop, LLNL, (925) 423-9802, bishop33@llnl.gov

    “A new employee will soon be added to the roster of those working on Level 2 of the National Ignition Facility’s (NIF) Target Bay. His name is D2T3, and his duties will be a bit different than his colleagues.

    D2T3 — named for the hydrogen isotopes that serve as fuel for NIF’s fusion targets — is a radiation-detecting, remote controlled robot. Currently in testing and training mode, he will be fully deployed in September after three years of development.

    robot
    System Manager Casey Schulz successfully running D2T3 through his paces, negotiating obstacles in the Target Bay.

    D2T3 has found his place in the NIF duty roster due to the continuing success of the facility’s experiments. As NIF laser shots continue to yield higher and higher neutron yields — a marker of the facility’s ultimate goal, fusion ignition – the immediate environment of the Target Bay is inhospitable to humans. Currently, the area remains sealed for a number of hours based on radiation decay models before radiation technicians enter to verify that levels are safe. As a safety precaution, this wait is longer than models predict to provide a safety buffer.

    man
    Camera faceoff between TID’s Matthew Story and D2T3 in TB Level 2.

    However, D2T3 doesn’t have the same constraints as his human colleagues. He can patrol the Target Bay immediately after a shot and measure the remaining radiation levels, providing an accurate and timely notification for when it is safe to re-enter the area. He also can provide real-time decay information, allowing for fine-tuning of the current models.

    ‘This is the first actual, non-tethered robot we’ve got,’ said Casey Schulz, a mechanical and robotics engineer who serves as the system manager for D2T3. ‘It expands the capability of NIF, improves efficiency and maintains the high level of safety we require. It’s logically the next step as we continue to reach higher and higher neutron yields.’”

    See the full article here.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
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  • richardmitnick 1:49 pm on July 10, 2013 Permalink | Reply
    Tags: , Laser Technology, ,   

    From M.I.T. : “A new way to trap light” 

    MIT researchers discover a new phenomenon that could lead to new types of lasers and sensors.

    July 10, 2013
    David L. Chandler

    “There are several ways to “trap” a beam of light — usually with mirrors, other reflective surfaces, or high-tech materials such as photonic crystals. But now researchers at MIT have discovered a new method to trap light that could find a wide variety of applications.

    The new system, devised through computer modeling and then demonstrated experimentally, pits light waves against light waves: It sets up two waves that have the same wavelength, but exactly opposite phases — where one wave has a peak, the other has a trough — so that the waves cancel each other out. Meanwhile, light of other wavelengths (or colors) can pass through freely.

    phot
    Light is found to be confined within a planar slab with periodic array of holes, although the light is theoretically “allowed” to escape. Blue and red colors indicate surfaces of equal electric field. Image: Chia Wei Hsu

    The researchers say that this phenomenon could apply to any type of wave: sound waves, radio waves, electrons (whose behavior can be described by wave equations), and even waves in water.

    The discovery is reported this week in the journal Nature by professors of physics Marin Soljačić and John Joannopoulos, associate professor of applied mathematics Steven Johnson, and graduate students Chia Wei Hsu, Bo Zhen, Jeongwon Lee and Song-Liang Chua.

    See the full article here.


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  • richardmitnick 3:58 pm on June 21, 2013 Permalink | Reply
    Tags: , , Laser Technology, ,   

    From Symmetry: “Physicists boost electrons with lasers” 

    Accelerator physicists at SLAC celebrate a successful step toward building smaller, cheaper accelerators.

    June 21, 2013
    Lori Ann White

    “Accelerator researchers at SLAC’s Next Linear Collider Test Accelerator have successfully created high-quality, fast-moving electron beams in a new type of particle acceleration that uses an off-the-shelf laser to give electron bunches a boost.

    three
    Personnel not credited. Photo: Matt Beardsley, SLAC

    If it can be scaled up, the new technique is capable of reducing the size and expense of future accelerators. That, combined with the high quality of the accelerated beams, would make the method especially useful for future electron–position colliders or extremely powerful light sources capable of delivering not just X-rays, but gamma rays. The recent work borrows a page from the laser–electron interaction that takes place in free-electron lasers—machines developed out of particle physics that study the structure of materials in unprecedented detail. In a free-electron laser, accelerated electrons are sent through a series of magnets to make the electrons slalom back and forth, which causes them to generate intense, coherent X-ray light: an X-ray laser. Essentially, the machine makes a laser from accelerated electrons. The recent advancement takes the free-electron laser process and rewrites it—backward. In Physical Review Letters this month, researchers describe their success at using optical laser pulses to accelerate electrons in two stages in order to obtain a high-quality beam. In short, instead of accelerating electron beams to make lasers, the technique uses lasers to accelerate electron beams.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


     
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