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  • richardmitnick 12:48 pm on September 16, 2014 Permalink | Reply
    Tags: , , , Physics,   

    From phys.org: “Neutrino trident production may offer powerful probe of new physics” 

    physdotorg
    phys.org

    September 15, 2014
    Lisa Zyga

    The standard model (SM) of particle physics has four types of force carrier particles: photons, W and Z bosons, and gluons. But recently there has been renewed interest in the question of whether there might exist a new force, which, if confirmed, would result in an extension of the SM. Theoretically, the new force would be carried by a new gauge boson called Z’ or the “dark photon” because this “dark force” would be difficult to detect, as it would affect only neutrinos and unstable leptons.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    “Much of the complexity and beauty of our physical world depends on only four forces,” Wolfgang Altmannshofer, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, told Phys.org. “It stands to reason that any additional new force discovered will bring with it interesting and unexpected phenomena, although it might take some time to fully appreciate and understand its implications.”

    Now in a new study published in Physical Review Letters, Altmannshofer and his coauthors from the Perimeter Institute have shown that the parameter space where a new dark force would exist is significantly restricted by a rare process called neutrino trident production, which has only been experimentally observed twice.

    graph
    Parameter space for the Z’ gauge boson. The light gray area is excluded at 95% C.L. by the CCFR measurement of the neutrino trident cross section. The dark gray region with the dotted contour is excluded by measurements of the SM Z boson decay to four leptons at the LHC. The purple region is the area favored by the muon g-2 discrepancy that has not yet been ruled out, but future high-energy neutrino experiments are expected to be highly sensitive to this low-mass region. Credit: Altmannshofer, et al. ©2014 American Physical Society

    In neutrino trident production, a pair of muons is produced from the scattering of a muon neutrino off a heavy atomic nucleus. If the new Z’ boson exists, it would increase the rate of neutrino trident production by inducing additional particle interactions that would constructively interfere with the expected SM contribution.

    The new force could also solve a long-standing discrepancy in the [Fermilab] muon g-2 experiment compared to the SM prediction. By coupling to muons, the new force might solve this problem.

    However, the two existing experimental results of neutrino trident production (performed by the CHARM-II collaboration and the CCFR collaboration) are both in good agreement with SM predictions, which places strong constraints on any possible contributions from a new force.

    In the new paper, the physicists have analyzed the two experimental results and extended the support for ruling out a dark force, at least over a large portion of the parameter space relevant to solving the muon g-2 discrepancy (when the mass of the Z’ boson is greater than about 400 MeV). The results not only constrain the dark force, but more generally any new force that couples to both muons and muon neutrinos.

    “We showed that neutrino trident production is the most sensitive probe of a certain type of new force,” Altmannshofer said. “Particle physics is driven by the desire to discover new building blocks of nature, and ultimately the principles that organize these building blocks. Our findings establish a new direction where new forces can be searched for, and highlight the planned neutrino facility at Fermilab (the Long-Baseline Neutrino Experiment [LBNE]) as a potentially powerful experiment where such forces can be searched for in the future.”

    Overall, the current results suggest that LBNE would have very favorable prospects for searching for the Z’ boson in the relevant, though restricted, regions of parameter space.

    See the full article here.

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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  • richardmitnick 3:56 pm on September 15, 2014 Permalink | Reply
    Tags: , Physics,   

    From Triumf: “Postdoc Publishes Theory Breakthrough” 


    Triumf Lab

    15 September 2014
    Nick Leach, Outreach Assistant

    The basic interaction between the constituents of an atomic nucleus (‘nucleons‘ means neutrons or protons) has been well understood for decades; however, the interaction’s strength has meant that calculations for all but the very simplest nuclear systems (e.g. the deuteron = 1 proton + 1 neutron) were initially too complex to do from basic principles, necessitating various approximation methods to make reliable predictions. Nonetheless, theoretical groups worldwide have persevered in their attempts at establishing reliable “ab initio” techniques, and much progress has been made in describing ever-larger nuclei starting from the fundamental nucleon forces. TRIUMF theorists have been at the forefront of many of these advances.

    neu
    The quark structure of the neutron. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

    pro
    The quark structure of the proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

    Recently, scientists from TRIUMF and the Lawrence Livermore National Laboratory (LLNL) published a paper in the prestigious Physical Review Letters outlining a technique which for the first time enables researchers to analyze systems of three nuclear clusters in relative motion while treating the individual nucleons as fundamental components interacting by accurate nucleon-nucleon interactions. The work by the Theory postdoc Carolina Romero-Redondo and Petr Navratil (Theory Department, TRIUMF) in conjunction with Sofia Quaglioni and Guillaume Hupin (LLNL) has produced the first successful ab initio analysis describing energy states in the He-6 nucleus (2 protons + 4 neutrons).

    chart

    cr
    Carolina Romero-Redondo

    He-6 is an exotic nucleus that can be described as a three-cluster “halo” nucleus – a tightly bound He-4 core orbited by two neutrons. Part of what makes this particular nucleus so fascinating is that though the trio are bound together when all three bodies are present, removing just one renders the whole structure unstable. These are known as “Borromean” nuclei, after the similarly named Borromean rings, which exhibit a similar all-or-nothing structure. The He-6 nucleus is difficult to study experimentally and as such its energy spectrum is not yet firmly established. Excitingly, the results by Romero-Redondo, et al. are consistent with recent experiments, correctly identifying some known energy states (‘resonances’). They also predict new energy states and do not find others (e.g. low-energy “1-“ state) predicted by other formalisms.

    In the future, this new approach will be applied to study systems such as H-5 as a 3H+n+n trio, and Li-11 as a 9Li+n+n configuration.

    Having completed her term at TRIUMF, Carolina will continue her innovative research on three-cluster systems at her new appointment at LLNL.

    Congratulations to Romero-Redondo and her colleagues for this excellent contribution!

    See the full article here.

    World Class Science at Triumf Lab, British Columbia, Canada
    Canada’s national laboratory for particle and nuclear physics
    Member Universities:
    University of Alberta, University of British Columbia, Carleton University, University of Guelph, University of Manitoba, Université de Montréal, Simon Fraser University,
    Queen’s University, University of Toronto, University of Victoria, York University. Not too shabby, eh?

    Associate Members:
    University of Calgary, McMaster University, University of Northern British Columbia, University of Regina, Saint Mary’s University, University of Winnipeg, How bad is that !!
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  • richardmitnick 3:27 pm on September 15, 2014 Permalink | Reply
    Tags: , , , PETRA III, Physics,   

    From DESY: “Double topping-out celebrations at DESY” 

    DESY
    DESY

    Two new experimental halls for research light source PETRA III

    Today DESY celebrates the topping-out of two large experimental halls for the research light source PETRA III.Ten additional beamlines, which will serve in the PETRA III particle accelerator’s high intensity X-ray experiments, are under construction in a space measuring approximately 6000 square meters; the facility will also include en-suite offices and laboratory spaces for scientists.The experimentation capabilities at the PETRA III synchrotron radiation source will be considerably increased due to the expansion project.The first new beamlines of the 80-million-Euro-project will be ready for operation beginning in autumn 2015.
    Zoom (17 KB)

    pit

    “With the new experimental stations, we are significantly expanding the research capabilities of PETRA III, for example, with new nanospectroscopy and materials research technologies,” says Chairman of the DESY Board of Directors Professor Helmut Dosch at the event. “At the same time, we will be fulfilling the enormous worldwide scientific demand for the best synchrotron radiation source in the world.”

    Hamburg´s Science Senator Dr. Dorothee Stapelfeldt says: “The senate’s aim is to develop Hamburg into one of the leading locations for research and innovation in Europe.In order to do so, it is essential to further raise the profiles of universities and research institutions in close dialogue with all stakeholders.Hamburg already occupies a leading position in structural research.The ground-breaking cooperation between DESY, the university and their partners at the Bahrenfeld research campus has been clearly recognized internationally.With the two new experimental halls, PETRA’s synchrotron radiation will be made available to even more researchers from all over the world in the future.”

    “With a total of ten new beamlines, the allure of Hamburg as a location for cutting-edge research will continue to increase, nationally and internationally,” says Dr. Beatrix Vierkorn-Rudolph (BMBF), Chairperson of the DESY Foundation Council. “With its excellent research opportunities, PETRA III contributes to rapidly transfering the results of basic research into application while also strengthening the innovative power of Germany.”

    DESY’s 2.3-kilometre-long PETRA III ring accelerator produces high intensity, highly collimated X-ray pulses for a diverse range of physical, biological and chemical experiments.Fourteen measuring stations, which can accommodate up to thirty experiments, already exist in an approximately 300-metre-long experimental hall.The properties of light pulses, which PETRA delivers to the different measuring stations, are thereby precisely attuned to the different research disciplines.Using the extremely brilliant X-rays, researchers study, for example, innovative solar cells, observe the dynamics of cell membranes and analyse fossilised dinosaur eggs.

    PETRA III, the world´s best X-ray source of its kind, has been heavily over-booked since it began operations in 2009.The PETRA III Extension Project was begun in December 2013 to give more scientists access to the unique experimental possibilities of this research light source and to broaden PETRA III’s research portfolio in experimental technologies:measuring approximately 6000 square meters in their entirety, the two new experimental halls house enough space for technical installations of up to ten additional beam lines, and an additional 1400 square metres provide office and laboratory space for the scientists.The beam lines and measuring instruments in the new halls are under construction in close cooperation with the future user community and are, in part, collaborative research projects.Three of the future PETRA beamlines will be constructed as an international partnership with Sweden, India and Russia.

    Altogether approximately 170 metres of the PETRA tunnel and accelerator have been dismantled since February to build the new experimental halls. Since August, the accelerator, equipped with special magnets for producing X-ray radiation, has been under reconstruction within the new tunnel areas that have already been completed.After the preliminary construction phase of the experimental halls, they are to be developed further from December 2014 onward; the accelerator will at the same time resume operation.The experiments will re-start in the PETRA III experimental hall “Max von Laue” beginning in April 2015 and the first measuring stations in the new, still unnamed halls should gradually become ready for operation in autumn 2015 and the start of 2016.

    The extension’s total budget of approximately 80 million Euros stems in large part from the Helmholtz Association’s expansion funds as well as funds from the Federal Ministry of Research, the Free and Hanseatic City of Hamburg and DESY.Collaborative partners from Germany and abroad cover approximately one third of the costs.

    See the full article here.

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

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  • richardmitnick 12:26 pm on September 14, 2014 Permalink | Reply
    Tags: , , Physics,   

    From Rutgers: “Rutgers Physics Professors Find New Order in Quantum Electronic Material” 

    Rutgers University
    Rutgers University

    January 30, 2013
    Media Contact: Carl Blesch
    732-932-7084 x616
    E-mail: cblesch@ur.rutgers.edu

    May open door to new kinds of materials, magnets and superconductors

    Two Rutgers physics professors have proposed an explanation for a new type of order, or symmetry, in an exotic material made with uranium – a theory that may one day lead to enhanced computer displays and data storage systems and more powerful superconducting magnets for medical imaging and levitating high-speed trains.

    pc
    Piers Coleman

    Their discovery, published in this week’s issue of the journal Nature, has piqued the interest of scientists worldwide. It is one of the rare theory-only papers that this selective publication accepts. Typically the journal’s papers describe results of laboratory experimentation.

    Collaborating with the Rutgers professors was a postdoctoral researcher at Massachusetts Institute of Technology (MIT) who earned her doctorate at Rutgers.

    “Scientists have seen this behavior for 25 years, but it has eluded explanation.” said Piers Coleman, professor in the Department of Physics and Astronomy in the School of Arts and Sciences. When cooled to 17.5 degrees above absolute zero or lower (a bone-chilling minus 428 degrees Fahrenheit), the flow of electricity through this material changes subtly.

    The material essentially acts like an electronic version of polarized sunglasses, he explains. Electrons behave like tiny magnets, and normally these magnets can point in any direction. But when they flow through this cooled material, they come out with their magnetic fields aligned with the material’s main crystal axis.

    This effect, claims Coleman, comes from a new type of hidden order, or symmetry, in this material’s magnetic and electronic properties. Changes in order are what make liquid crystals, magnetic materials and superconductors work and perform useful functions.

    “Our quest to understand new types of order is a vital part of understanding how materials can be developed to benefit the world around us,” he said.

    Similar discoveries have led to technologies such as liquid crystal displays, which are now ubiquitous in flat-screen TVs, computers and smart phones, although the scientists are quick to acknowledge that their theoretical discovery won’t transform high-tech products overnight.

    pc
    Premala Chandra
    Nick Romanenko

    Coleman, along with Rutgers colleague Premala Chandra and MIT collaborator Rebecca Flint, describe what they call a “hidden order” in this compound of uranium, ruthenium and silicon. Uranium is commonly known for being nuclear reactor fuel or weapons material, but in this case physicists value it as a heavy metal with electrons that behave differently than those in common metals.

    Recent experiments on the material at the National High Magnetic Field Laboratory at Los Alamos National Laboratory in New Mexico provided the three physicists with data to refine their discovery.

    “We’ve dubbed our fundamental new order ‘hastatic’ order, named after the Greek word for spear,” said Chandra, also a professor in the Department of Physics and Astronomy. The name reflects the highly ordered properties of the material and its effect on aligning electrons that flow through it.

    “This new category of order may open the world to new kinds of materials, magnets, superconductors and states of matter with properties yet unknown,” she said. The scientists have predicted other instances where hastatic order may show up, and physicists are beginning to test for it.

    The scientists’ work was funded by the National Science Foundation and the Simons Foundation. Flint is a Simons Postdoctoral Fellow in physics at MIT.

    See the full article here.

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

    Rutgers Seal

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  • richardmitnick 8:53 am on September 14, 2014 Permalink | Reply
    Tags: , , Physics   

    From Huff Post via PBS NOVA: “Scientists Capture The Sound Of A Single Atom, And Apparently It’s A ‘D-Note'” 

    Huffington Post
    The Huffington Post

    This article was brought forward by PBS NOVA
    PBS NOVA

    09/12/2014
    Macrina Cooper-White

    What does an atom sound like? Apparently it’s a “D-note.”

    That’s according to scientists at Chalmers University of Technology in Göteborg, Sweden, who have revealed in a new study that they’ve captured the sound of a single atom.

    “We have opened a new door into the quantum world by talking and listening to atoms,” study co-author Per Delsing, a physics professor at the university, said in a written statement. “Our long term goal is to harness quantum physics so that we can benefit from its laws, for example in extremely fast computers.”

    For their study, Delsing and his colleagues constructed an artificial atom 0.01 millimeters long and placed it on the end of a superconducting material. Then they guided sound waves along the surface of the material, bounced sound off of the atom, and recorded what came back using a tiny microphone located on the other end of the material.

    atom
    On the right, an artificial atom generates sound waves consisting of ripples on the surface of a solid material. The sound, known as a surface acoustic wave is picked up on the left by a “microphone” composed of interlaced metal fingers.

    “According to the theory, the sound from the atom is divided into quantum particles,” study co-author Martin Gustafsson, a post-doctoral researcher at Columbia University, said in the statement. “Such a particle is the weakest sound that can be detected.”

    That sound was a “D-note” about 20 octaves above the highest note on the piano, which is a pitch much higher than the human ear can detect.

    The researchers said that manipulating sound on the quantum level may lead to new developments in quantum computing. Sound has a short wavelength and travels 100,000 times slower than light, which means it’s much easier to control.

    “Whether it has implications for quantum computing may be too early to tell, but it expands the toolbox for technologies to work with,” Steve Rolston, co-director of the University of Maryland’s Joint Quantum Institute, who was not involved in the study, told Discovery News.

    The study was published online in the journal Science on September 11, 2014.

    See the full article here.

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  • richardmitnick 8:41 am on September 3, 2014 Permalink | Reply
    Tags: , , , , , LUNA, Physics,   

    From physicsworld.com: “Big Bang ruled out as origin of lithium-6″ 

    physicsworld
    physicsworld.com

    Sep 2, 2014
    Hamish Johnson

    Collisions between hydrogen and helium nuclei deep under a mountain in Italy have confirmed a mystery of cosmic proportions: why the amount of lithium-6 observed in today’s universe is so different from the amount that theory predicts was produced shortly after the Big Bang. Working at the Laboratory for Underground Nuclear Astrophysics (LUNA) at Gran Sasso, an international team of researchers has measured for the first time how fast lithium-6 is produced under conditions similar to those when the universe was a few minutes old. The measured rate suggests that almost all lithium-6 was actually produced well after the Big Bang – something that current theories of nucleosynthesis cannot explain.

    The only three elements created in the early universe before stars and galaxies began to form were hydrogen, helium and lithium. According to Big Bang nucleosynthesis (BBN) theory, protons and neutrons combined to form these three elements just a few minutes after the Big Bang. The snag is that while the theory does a good job of predicting the observed abundances of hydrogen and helium isotopes in the universe, it fails miserably when it comes to the two stable lithium isotopes: lithium-6 and lithium-7.

    As far as lithium-7 is concerned, numerous observations suggest that there is much less of it in the universe than predicted with BBN, with the theory that underlies the prediction having been confirmed in 2006 by experiments done at LUNA by Daniel Bemmerer of Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany and colleagues. Now, Bemmerer and an international team of physicists have turned their attention to lithium-6, which accounts for about 7% of the lithium here on Earth.

    db
    Recreating the minutes after the Big Bang

    A thousand times more abundant

    The BBN model predicts that lithium-6 should account for about two out of every 100,000 lithium nuclei in “metal-poor” stars, which are believed to be among the first stars to have formed and so should reflect the composition of the early universe. However, observations made in 2006 by Martin Asplund of the Australian National University and colleagues suggest that the abundance of lithium-6 is more than a thousand times greater in such stars, accounting for about 5% of all the lithium present. The question, therefore, is whether the calculations or the observations were wrong.

    The production of lithium-6 by BBN should be dominated by one nuclear reaction, namely the collision and subsequent fusion of deuterium (hydrogen-2) with helium-4 to create lithium-6 and a gamma ray. Bemmerer and colleagues have now used the 400 kV accelerator at LUNA to study this interaction at two collision energies that would have occurred in the early universe. They did this by firing an intense beam of helium-4 nuclei at a target of deuterium gas and monitoring the collisions for the gamma rays associated with the production of lithium-6.

    Minimizing the background

    The probability that this specific fusion process occurs is very low, and so an important experimental challenge for the physicists was to see the weak gamma-ray signal among all the other radiation produced by the collisions, as well as background signals from naturally occurring radioactive materials and cosmic rays. By going deep underground, LUNA’s researchers were able to reduce the cosmic-ray background, while the effect of naturally occurring radon gas was minimized by flushing the experimental area with nitrogen gas.

    “For the first time, we could actually study the lithium-6 production in one part of the Big Bang energy range with our experiment.”
    Daniel Bremmerer, HZDR

    After carefully analysing tiny bumps in the gamma-ray spectra acquired during two experimental runs, the team calculated the rate at which lithium-6 is produced by fusion – finding it to be more or less as was expected. “For the first time, we could actually study the lithium-6 production in one part of the Big Bang energy range with our experiment,” says Bemmerer. The team then used BBN to calculate the ratio of lithium-6 to lithium-7 that should have been present in the early universe. The result is of the same order of magnitude as previously calculated, albeit a bit smaller, which makes the observation of high levels of lithium-6 in metal-poor stars even more mysterious. “Should unusual lithium concentrations be observed in the future, we know, thanks to the new measurements, that it cannot be down to the primordial nucleosynthesis,” says Bremmerer.
    Hints of new physics?

    As for the origin of most of the lithium-6 in the universe, this latest measurement reinforces the argument that it could not have been forged in the early universe. One possibility is that the isotope is produced in stellar flares. A much more radical suggestion is that the excess of lithium-6 was created by hitherto unknown physical processes, making cosmic measurements of the isotope a potential probe of physics beyond the Standard Model of particle physics.

    The research is reported in Physical Review Letters.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

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  • richardmitnick 4:53 pm on August 28, 2014 Permalink | Reply
    Tags: , Physics,   

    From PPPL: “PPPL lends General Electric a hand in developing an advanced power switch” 


    PPPL

    August 28, 2014
    John Greenwald

    Scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) are assisting General Electric Co. in developing an electrical switch that could help lower utility bills. The advanced switch “could contribute to a smarter, more advanced, more reliable, and more secure electric grid,” according to the DOE’s Advanced Research Projects Agency-Energy (ARPA-E), which is funding the GE project.

    switch
    Laboratory test of a liquid-metal cathode. (Photo by General Electric Co.)

    The company is drawing upon PPPL’s know-how in dealing with plasma, the hot, electrically charged gas that researchers control with magnetic fields to fuel fusion reactions. Plasma will form the heart of the proposed GE device, which would use a plasma-filled tube to switch electricity on and off in power-conversion systems.

    This gas-filled tube would replace the bulky and costly assemblies of semiconductor switches now used in systems that convert the direct current (DC) coming from long-distance power lines to the alternating current (AC) that lights homes and businesses. Such systems also convert AC current to DC current for transmission between AC power grids.

    GE is turning to PPPL for help with these tasks:

    • Modeling plasma properties for different magnetic-field configurations and gas pressures. “There aren’t many places with a demonstrated ability to model this type of plasma,” said Timothy Sommerer a physicist at GE Global Research Center who heads the switch project. “These guys [at PPPL] really came through and said they could do it.”

    • Developing a method for protecting the cathode — the negative terminal inside the plasma-filled tube — from damage from the positively charged ions, or atomic nuclei, in the dense current that flows through the gas. “You need to operate above a certain current density,” Sommerer said. “But this leads to ion impact that can damage the cathode. So what you want is high current-density and low cathode-damage.”

    Sommerer has tapped a team led by physicist Igor Kaganovich, deputy head of the PPPL Theory Department, for the modeling task. The team employs specially designed codes to simulate the plasma, said Kaganovich, who works with physicists Alexander Khrabrov and Johan Carlsson on the project. Joining them for the summer were students Mikhail Khodak of Princeton University and David Keating of the University of California-Berkeley.

    For tips on protecting the cathode, GE has been studying PPPL’s use of liquid lithium to prevent damage to the divertor that exhausts heat in fusion facilities. The flowing liquid metal forms a wet, self-healing barrier that constantly replenishes itself, said physicist Michael Jaworski, an expert on the use of lithium in fusion experiments.

    GE is working with cathodes made of liquid gallium for its self-healing properties. Learning of PPPL’s work with liquid lithium was “just serendipitous,” Sommerer said, since GE initially sought the Laboratory’s plasma-modeling skills. But “conditions in the divertor are pretty similar to what the cathode would face,” he noted, making PPPL’s experience quite useful to know.

    For tips on protecting the cathode, GE has been studying PPPL’s use of liquid lithium to prevent damage to the divertor that exhausts heat in fusion facilities. The flowing liquid metal forms a wet, self-healing barrier that constantly replenishes itself, said physicist Michael Jaworski, an expert on the use of lithium in fusion experiments.

    GE is working with cathodes made of liquid gallium for its self-healing properties. Learning of PPPL’s work with liquid lithium was “just serendipitous,” Sommerer said, since GE initially sought the Laboratory’s plasma-modeling skills. But “conditions in the divertor are pretty similar to what the cathode would face,” he noted, making PPPL’s experience quite useful to know.

    See the full article here.

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University.

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  • richardmitnick 6:49 pm on August 26, 2014 Permalink | Reply
    Tags: , , CERN AWAKE, Physics   

    From CERN: “Awakening the potential of plasma acceleration” 

    CERN New Masthead

    26 Aug 2014
    Katarina Anthony

    Civil engineering has begun for the new Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN. This proof-of-principle experiment will harness the power of wakefields generated by proton beams in plasma cells, producing accelerator gradients hundreds of times higher than those used in current radiofrequency cavities.

    dig

    Like all of CERN’s experiments, AWAKE is a collaborative endeavour with institutes and organisations participating around the world. “But unlike fixed-target experiments, where users take over once CERN has delivered the facility, in AWAKE, the synchronised proton, electron and laser beams provided by CERN are an integral part of the experiment,” says project leader Edda Gschwendtner. “CERN’s involvement in the project goes well beyond providing infrastructure and services.”

    Construction teams are already turning the area at CERN that housed the CERN Neutrinos to Gran Sasso (CNGS) experiment into a home for AWAKE.

    “We have removed part of the proton beam line and cleared the area upstream of the CNGS target to make way for the AWAKE installation, including a laser and 10 metre plasma cell,” says Gschwendtner. “CNGS’s area downstream of the target, however, has been left untouched. As it is radioactive, we constructed a new shielding wall in July so that the AWAKE facility upstream can be a safe, supervised working area for users.”

    The AWAKE facility will also feature a clean room for the laser, a dedicated area for the electron source and two new tunnels: one small tunnel to hold the laser beam (which ionises the plasma and seeds the wakefields); and a second, larger tunnel that will be home to the electron beam line (the “witness beam” accelerated by the plasma). These new tunnels are currently being carved out for the facility (see image).

    The AWAKE team at the Max Planck Institute for Physics (link is external) in Munich, Germany, is preparing to move both equipment and know-how to CERN. “In Munich, we are working with a 3-metre prototype of the plasma cell,” says Allen Caldwell, AWAKE spokesperson. “Our focus is on the science: learning the properties of the plasma cell as well as possible before we start with the ‘real thing’.”

    “We are also addressing a number of hardware issues,” says Patric Muggli, AWAKE Physics and Experiment Coordinator. “For example, we are creating valves that allow the laser, proton and electron beams to enter the plasma cell. These need to be extremely fast but also durable, opening and closing an unprecedented 40,000 times in its lifetime.”

    Although new technology is being created for AWAKE, the experiment also re-uses existing equipment from CNGS, CLIC/CTF3 and other CERN facilities. The experiment will be conducted in two phases, the first starting in 2016.

    awake2

    AWAKE will use proton beams from the Super Proton Synchrotron (SPS) in the CERN Neutrinos to Gran Sasso (CNGS) facility (see image above for proposed location). These protons will be injected into a 10-metre plasma cell to initiate strong wakefields. A second beam – the “witness” electron beam – would then be accelerated by the wakefields, gaining up to several gigavolts of energy. Following AWAKE’s approval in autumn 2013, the first proton beams are expected to be sent to the plasma cell at the end of 2016.

    AWAKE would be the world’s first proton-driven plasma wakefield acceleration experiment. Besides demonstrating how protons can be used to generate wakefields, AWAKE will also develop the necessary technologies for long-term, proton-driven plasma acceleration projects.

    See the full article here.
    See the article on AWAKE here.

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  • richardmitnick 1:23 pm on August 26, 2014 Permalink | Reply
    Tags: , Physics,   

    From SLAC: “X-ray Laser Probes Tiny Quantum Tornadoes in Superfluid Droplets” 


    SLAC Lab

    August 21, 2014

    An experiment at the Department of Energy’s SLAC National Accelerator Laboratory revealed a well-organized 3-D grid of quantum “tornadoes” inside microscopic droplets of supercooled liquid helium – the first time this formation has been seen at such a tiny scale.

    image
    In this illustration, a patterned 3-D grid of tiny whirlpools, called quantum vortices, populates a nanoscale droplet of superfluid helium. Researchers found that in a micron-sized droplet, the density of vortices was 100,000 times greater than in any previous experiment on superfluids. An artistic rendering of a wheel-shaped droplet can be seen in the distance. (SLAC National Accelerator Laboratory)

    The findings by an international research team provide new insight on the strange nanoscale traits of a so-called “superfluid” state of liquid helium. When chilled to extremes, liquid helium behaves according to the rules of quantum mechanics that apply to matter at the smallest scales and defy the laws of classical physics. This superfluid state is one of just a few examples of quantum behavior on a large scale that makes the behavior easier to see and study.

    The results, detailed in the Aug. 22 issue of Science, could help shed light on similar quantum states, such as those in superconducting materials that conduct electricity with 100 percent efficiency or the strange collectives of particles, dubbed Bose-Einstein condensates, which act as a single unit.

    “What we found in this experiment was really surprising. We did not expect the beauty and clarity of the results,” said Christoph Bostedt, a co-leader of the experiment and a senior scientist at SLAC’s Linac Coherent Light Source (LCLS), the DOE Office of Science User Facility where the experiment was conducted.

    machine
    This instrument, called CAMP, was used for the helium nanodroplets experiment at the Linac Coherent Light Source’s Atomic, Molecular and Optical Science (AMO) experimental station. (SLAC National Accelerator Laboratory)

    “We were able to see a manifestation of the quantum world on a macroscopic scale,” said Ken Ferguson, a PhD student from Stanford University working at LCLS.

    While tiny tornadoes had been seen before in chilled helium, they hadn’t been seen in such tiny droplets, where they were packed 100,000 times more densely than in any previous experiment on superfluids, Ferguson said.

    Studying the Quantum Traits of a Superfluid

    Helium can be cooled to the point where it becomes a frictionless substance that remains liquid well below the freezing point of most fluids. The light, weakly attracting atoms have an endless wobble – a quantum state of perpetual motion that prevents them from freezing. The unique properties of superfluid helium, which have been the subject of several Nobel prizes, allow it to coat and climb the sides of a container, and to seep through molecule-wide holes that would have held in the same liquid at higher temperatures.

    In the LCLS experiment, researchers jetted a thin stream of helium droplets, like a nanoscale string of pearls, into a vacuum. Each droplet acquired a spin as it flew out of the jet, rotating up to 2 million turns per second, and cooled to a temperature colder than outer space. The X-ray laser took snapshots of individual droplets, revealing dozens of tiny twisters, called “quantum vortices,” with swirling cores that are the width of an atom.

    The fast rotation of the chilled helium nanodroplets caused a regularly spaced, dense 3-D pattern of vortices to form. This exotic formation, which resembles the ordered structure of a solid crystal and provides proof of the droplets’ quantum state, is far different than the lone whirlpool that would form in a regular liquid, such as briskly stirred cup of coffee.

    More Surprises in Store

    Researchers also discovered surprising shapes in some superfluid droplets. In a normal liquid, droplets can form peanut shapes when rotated swiftly, but the superfluid droplets took a very different form. About 1 percent of them formed unexpected wheel-like shapes and reached rotation speeds never before observed for their classical counterparts.

    Oliver Gessner, a senior scientist at Lawrence Berkeley Laboratory and a co-leader in the experiment, said, “Now that we have shown that we can detect and characterize quantum rotation in helium nanodroplets, it will be important to understand its origin and, ultimately, to try to control it.”

    Andrey Vilesov of the University of Southern California, the third experiment co-leader, added, “The experiment has exceeded our best expectations. Attaining proof of the vortices, their configurations in the droplets and the shapes of the rotating droplets was only possible with LCLS imaging.”

    He said further analysis of the LCLS data should yield more detailed information on the shape and arrangement of the vortices: “There will definitely be more surprises to come.”

    Other research collaborators were from the Stanford PULSE Institute; University of California, Berkeley; the Max Planck Society; Center for Free-Electron Laser Science at DESY; PNSensor GmbH; Chinese University of Hong Kong; and Kansas State University. This work was supported by the National Science Foundation, the U.S. Department of Energy Office of Science and the Max Planck Society.

    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 6:02 am on August 26, 2014 Permalink | Reply
    Tags: , , Physics   

    From phys.org: “Physicists ‘freeze time’ to manipulate spin information in graphene” 

    physdotorg
    phys.org

    August 25, 2014
    Ans Hekkenberg

    Researchers from the FOM Foundation. and University of Groningen have found a way to preserve spin information for much longer than previously possible. They isolated the spin information from the influence of the outside world in a nanoscale graphene device, in which they can easily manipulate the information with electric fields. This feature makes their device an attractive candidate for future computer data storage and for logic devices based on spins. The researchers published their results online on 22 August 2014 in Physical Review Letters.

    graphene
    Graphene is an atomic-scale honeycomb lattice made of carbon atoms.

    device
    A schematic side view of the spintronics device. The dark grey graphene flake is protected by boron nitride layers (green). Voltages applied to the bottom electrode (bg) and the top electrode (tg) generate the electric field used for spin manipulation. The cobalt electrodes (numbered 1 to 5) are used to generate and detect spin information. Credit: Fundamental Research on Matter (FOM)

    The nanoscale device consists of a flake of graphene (a one-atom-thick layer of carbon) which is protected from the environment by stacked insulating layers of boron nitride. Electrons inside the graphene carry information: they each have a spin value (up or down), which is determined by the direction of their intrinsic magnetic moment. The spin values can be considered as computer bits, which can be used to transfer or store information.

    A challenge is that electron spins usually lose their values over time (the spin relaxation time), which causes information to be lost. In graphene, this usually takes about 0.2 nanoseconds (one nanosecond is a billionth of a second). However, with their protected device, the researchers managed to increase the spin relaxation time in graphene to more than 2 nanoseconds.

    Electric fields

    So far, physicists could only change the value of spins in graphene (and therefore the value of the ‘bits’) by using magnetic fields. Using two gate electrodes, the researchers now managed to manipulate the spin information in their device with electric fields instead. Since electric fields are much easier to generate in nanoscale devices, these results pave the way to future spintronic devices based on graphene.

    Spintronics

    image2
    A optical microscope image of the spintronic device (top view). The top electrode (tg) and cobalt electrodes (1 to 5) are yellow. The boron nitride layers (in green) encapsulate the graphene flake, which is outlined by the dotted line. Credit: Fundamental Research on Matter (FOM)

    In the field of spintronics (which stands for spin and electronics), spin is used to convey information instead of electrical charges. Spin based devices have lower power consumption and are less volatile when compared to charge based ones. For this reason spintronic devices have been considered as an alternative for computer components, for instance in memory technologies like M-RAM and STT-RAM.

    See the full article here.

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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