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  • richardmitnick 8:08 am on June 21, 2016 Permalink | Reply
    Tags: , , JLab, Variable angle slant hole collimator for breast imaging   

    From JLab: “Innovative device allows 3D imaging of the breast with less radiation” 

    6.21.16
    Kandice Carter,
    Jefferson Lab Public Affairs
    757-269-7263
    kcarter@jlab.org

    1
    Adding this variable angle slant hole collimator to an existing breast molecular imaging system allows the system to get six times better contrast of cancer lesions in the breast, providing the same or better image quality while also potentially reducing the radiation dose to the patient by half.

    Preliminary tests have demonstrated that a new device may enable existing breast cancer imagers to provide up to six times better contrast of tumors in the breast, while maintaining the same or better image quality and halving the radiation dose to patients. The advance is made possible by a new device developed for 3D imaging of the breast by researchers at the Department of Energy’s Thomas Jefferson National Accelerator Facility, Dilon Technologies and the University of Florida Department of Biomedical Engineering.

    In breast cancer screening, mammography is the gold standard. But about half of all women who follow standard screening protocol for 10 years will receive a false-positive result that will require additional screening, particularly women who have dense breast tissue. Used in conjunction with mammography, imaging based on nuclear medicine is currently being used as a successful secondary screening alongside mammography to reduce the number of false positive results in women with dense breasts and at higher risk for developing breast cancer.

    Now, researchers are hoping to improve this imaging technique, known as molecular breast imaging or breast specific gamma imaging, with better image quality and precise location (depth information) within the breast, while reducing the amount of radiation dose to the patient for these procedures.

    According to Drew Weisenberger, leader of the Jefferson Lab Radiation Detector and Imaging Group, a new device called a variable angle slant hole collimator provides all of these benefits and more. When used in a molecular breast imager, the device has just demonstrated in early studies to capture 3D molecular breast images at higher resolution than current 2D scans in a format that may be used alongside 3D digital mammograms.

    “These results really focus on the breast. We hope to build on this to perhaps improve the imaging of other organs,” Weisenberger said.

    The new device replaces a component in existing molecular breast imagers.

    While a mammogram uses X-rays to show the structure of breast tissue, molecular breast imagers show tissue function. For instance, cancer tumors are fast growing, so they gobble up certain compounds more rapidly that healthy tissue. A radiopharmaceutical made of such a compound will quickly accumulate in tumors. A radiotracer attached to the molecule gives off gamma rays, which can be picked up by the molecular breast imager.

    “You can image that accumulation external to the breast by using a gamma camera,” said Weisenberger.

    Current molecular breast imaging systems use a traditional collimator, which is essentially a rectangular plate of dense metal with a grid of holes, to “filter” the gamma rays for the camera. The collimator only allows the system to pick up the gamma rays that come straight out of the breast, through the holes of collimator, and into the imager. This provides for a clear, well-defined image of any cancer tumors.

    The variable angle slant hole collimator, or VASH collimator, is constructed from a stack of 49 tungsten sheets, each one a quarter of a millimeter thick and containing an identical array of square holes. The sheets are stacked like a deck of cards, with angled edges on two sides. The angle of the array of square holes in the stack can be easily slanted by two small motors that slide the individual sheets by their edges. The result is a systematic varying of the focusing angle of the collimator during the imaging procedure.

    “Now, you can get a whole range of angles of projections of the breast without moving the breast or moving the imager. You’re able to come in real close, you’re able to compress the breast, and you can get a one-to-one comparison to a 3D mammogram,” Weisenbeger explained.

    In a recent test of the system, the researchers evaluated the spatial resolution and contrast-to-noise ratio in images of a “breast phantom,” a plastic mockup of a breast with four beads inside simulating cancer tumors of varying diameter that are marked with a radiotracer. They found that using the VASH collimator with an existing breast molecular imaging system, they could get six times better contrast of tumors in the breast, which could potentially reduce the radiation dose to the patient by half from the current levels, while maintaining the same or better image quality. The test results match a published paper that predicted this performance via a Monte Carlo simulation.

    The collimator was built at Jefferson Lab and the test results were analyzed at the University of Florida with funds provided by a Commonwealth Research Commercialization Fund grant from the Commonwealth of Virginia’s Center for Innovative Technology, and with matching support provided by Dilon Technologies.

    The test results were presented at the 2016 Society of Nuclear Medicine and Molecular Imaging Annual Meeting in San Diego on June 13. The technologies developed for the Variable Angle Slant Hole Collimator are included in two filings to the U.S. Patent and Trademark Office.

    See the full article here .

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    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

    Jefferson Lab is supported by the Office of Science of the U.S. Department of Energy. 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, visit science.energy.gov.

    JLab campus

     
  • richardmitnick 3:39 pm on May 12, 2016 Permalink | Reply
    Tags: , , , JLab   

    From JLab: “Award enables research for more efficient accelerators” 

    May 12, 2016
    Kandice Carter
    Jefferson Lab Public Affairs
    757-269-7263
    kcarter@jlab.org

    1
    A furnace system designed by Jefferson Lab Staff Scientist Grigory Eremeev and his colleagues adds tin to the inside surface of niobium cavities. A niobium test cavity and tin are placed inside and heated up to 1200 degrees Celsius. At that temperature, the tin is vaporized by the heat. The tin vapor bonds to the inner surface of the niobium cavity, producing a layer of niobium-tin that is just a few thousandths of a millimeter thick.

    Grigory Eremeev wants to double the efficiency of some of the most efficient particle accelerators being used for research. Now, the staff scientist at the Department of Energy’s Thomas Jefferson National Accelerator Facility has just been awarded a five-year grant through DOE’s Early Career Research Program to do just that.

    Managed by the DOE’s Office of Science, the program provides support to exceptional researchers during the crucial early career years, when many scientists do their most formative work. Eremeev is one of 49 awardees this year, which includes 22 from the National Labs and 27 from universities. His award includes $500K per year for five years.

    “We invest in promising young researchers early in their careers to support lifelong discovery science to fuel the nation’s innovation system,” said Cherry Murray, director of DOE’s Office of Science. “We are proud of the accomplishments these young scientists already have made, and look forward to following their achievements in years to come.”

    Eremeev works with accelerator components made of a metal called niobium. Niobium is a shiny silver metal that becomes a superconductor when chilled to just a few degrees above absolute zero.

    For use in an accelerator, the niobium is formed into specially shaped accelerating structures called cavities. Niobium cavities harness and impart energy onto particles, thereby “accelerating” the particles for use in nuclear physics experiments for exploring the particles inside the nucleus of the atom.

    Superconducting niobium cavities can store energy with almost no losses, allowing the structures to accelerate a continuous beam of particles. Jefferson Lab’s Continuous Electron Beam Accelerator Facility was the first large-scale accelerator to use this technology.

    Jlab CEBAF
    Jlab CEBAF

    Because of its efficiency, CEBAF has been used to conduct many experiments in the nucleus of the atom that weren’t thought possible before, and a recent upgrade of the machine has taken advantage of new technology advances, yielding even more efficient accelerator cavities.

    But Eremeev thinks that these structures can be further improved, so he and his colleagues are looking at ways to optimize the preparation of these structures to coax improved performance from them.

    “We are trying new techniques to reach the potential of the material. So, we are trying different parameters to get better performance,” Eremeev says.

    One of the most promising new parameters that Eremeev and his colleagues are testing is the addition of other superconducting metals to the surface of niobium accelerator cavities, such as tin. Like niobium, tin is a shiny metal that becomes superconducting when cooled to low temperatures. The researchers are working to mix tin with the surface layer of niobium on the inside of the cavities to produce a thin layer of niobium-tin (called Nb3Sn). It’s thought that this alloy will provide a more efficient superconducting surface than pure niobium.

    Eremeev and his colleagues designed and constructed a furnace system to add tin to the inside surface of niobium cavities. A niobium cavity and tin are placed inside and heated up to 1200 degrees Celsius. At that temperature, the tin is vaporized by the heat. The tin vapor bonds to the inner surface of the niobium cavity, producing a layer of niobium-tin that is just a few thousandths of a millimeter thick.

    Eremeev says the niobium-tin cavities have already shown great promise in initial testing.

    “We want to understand and push the limits of the niobum-tin, trying to approach, as close as we can, the performance limitation of the superconductor,” he says.

    For instance, the niobium-tin cavities will stay superconducting at twice the temperatures that are needed for pure niobium accelerating cavities, which could provide significant operational cost savings for future accelerators using the technology.

    In the 12 GeV CEBAF, for instance, the niobium cavities must be kept near 2 Kelvin (-456 degrees Fahrenheit) when operating, which requires 10 MW of power to refrigerate. At double that temperature, 4 Kelvin, there is the potential to only require 6.5 MW of power, a significant savings.

    So far, tests of this new type of accelerator cavity have been limited to R&D units. Eremeev says the next step is to produce two full-size cavities and install them in a section of accelerator for testing under real-world operating conditions, a goal that is now made possible by the DOE Early Career Research Program grant.

    “We need to demonstrate it in a CEBAF five-cell cavity to show that it works,” he says.

    Jefferson Lab is a world-leading nuclear physics research laboratory devoted to the study of the building blocks of matter inside the atom’s nucleus – quarks and gluons – that make up 99 percent of the mass of our visible universe. Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

    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, visit science.energy.gov.

    See the full article here .

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    Thomas Jefferson National Accelerator Facility is managed by Jefferson Science Associates, LLC for the U.S. Department of Energy

    JLab campus

     
  • richardmitnick 4:06 pm on April 26, 2016 Permalink | Reply
    Tags: "Why Physics Needs Diamonds", , JLab,   

    From Jlab via DOE: “Why Physics Needs Diamonds” 

    April 26, 2016
    Kandice Carter

    1
    A detailed view of the diamond wafers scientists use to get a better measure of spinning electrons. | Photo courtesy of Jefferson Lab.

    Diamonds are one of the most coveted gemstones. But while some may want the perfect diamond for its sparkle, physicists covet the right diamonds to perfect their experiments. The gem is a key component in a novel system at Jefferson Lab that enables precision measurements to discover new physics in the sub-atomic realm — the domain of the particles and forces that build the nucleus of the atom.

    Explorations of this realm require unique probes with just the right characteristics, such as the electrons that are prepared for experiments inside the Continuous Electron Beam Accelerator Facility [CEBAF] at Jefferson Lab.

    Jlab CEBAF
    Jlab CEBAF

    CEBAF is an atom smasher. It can take ordinary electrons and pack them with just the right energy, group them together in just the right number and set those groups to spinning in just the right way to probe the nucleus of the atom and get the information that physicists want.

    But to ensure that electrons with the correct characteristics have been dialed up for the job, nuclear physicists need to be able to measure the electrons before they are sent careening into the nucleus of the atom. That’s where the diamonds in a device called the Hall C Compton Polarimeter come in. The polarimeter measures the spins of the groups of electrons that CEBAF is about to use for experiments.

    This quantity, called the beam polarization, is a key unit in many experiments. Physicists can measure it by shining laser light on the electrons as they pass by on their way to an experiment. The light will knock some of the electrons off the path, where they’re gathered up into a detector to be counted, a procedure that yields the beam polarization.

    Ordinarily, this detector would be made of silicon, but silicon is relatively easily damaged when struck by too many particles. The physicists needed something a bit hardier, so they turned to diamond, hoping it could also be a physicist’s best friend.

    The Hall C Compton Polarimeter uses a novel detector system built of thin wafers of diamond. Specially lab-grown plates of diamond, measuring roughly three-quarters of an inch square and a mere two hundredths of an inch thick, are outfitted like computer chips, with 96 tiny electrodes stuck to them. The electrodes send a signal when the diamond detector counts an electron.

    This novel detector was recently put to the test, and it delivered. The detector provided the most direct and accurate measurement to date of electron beam polarization at high current in CEBAF.

    But the team isn’t resting on its laurels: New experiments for probing the subatomic realm will require even higher accuracies. Now, the physicists are focused on improving the polarimeter, so that its diamonds will be ready to sparkle for the next precision experiment.

    See the full article here .

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    Thomas Jefferson National Accelerator Facility is managed by Jefferson Science Associates, LLC for the U.S. Department of Energy

     
  • richardmitnick 4:49 pm on December 22, 2015 Permalink | Reply
    Tags: , , , JLab   

    From JLab: “Jefferson Lab Accelerator Delivers Its First 12 GeV Electrons” 

    December 21, 2015
    Kandice Carter, Jefferson Lab Public Affairs
    757-269-7263
    kcarter@jlab.org

    1
    On December 14, full-energy 12 GeV electron beam was provided for the first time, to the Experimental Hall D complex, located in the upper, left corner of this aerial photo of the Continuous Electron Beam Accelerator Facility. Hall D is the new experimental research facility – added to CEBAF as part of the 12 GeV Upgrade project. Beam was also delivered to Hall A (dome in the lower left).

    The newly upgraded accelerator at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility has delivered full-energy electrons as part of commissioning activities for the ongoing 12 GeV Upgrade project. At 4:20 p.m. on Monday, Dec. 14, operators of the Continuous Electron Beam Accelerator Facility (CEBAF) delivered the first batch of 12 GeV electrons (12.065 GeV) to its newest experimental hall complex, Hall D.

    “Through part of the ongoing upgrade process, we have refurbished or replaced virtually every one of the many thousands of components in CEBAF,” said Allison Lung, deputy project manager for the CEBAF 12 GeV Upgrade project and Jefferson Lab assistant director. “Now, to see the machine already reaching its top design energy – It’s a testament to the hard work of the many Jefferson Lab staff members who have made it possible.”

    The 12 GeV Upgrade project, which is scheduled to be completed in September 2017, was designed to enable the machine to provide 12 GeV electrons, which is triple its original design and double its maximum operational energy before the upgrade. By increasing the energy of the electrons, scientists are increasing the resolution of the CEBAF microscope for probing ever more deeply into the nucleus of the atom. The $338 million upgrade entails adding ten new acceleration modules and support equipment to CEBAF, as well as construction of a fourth experimental hall, upgrades to instrumentation in the existing halls, and other upgrade components.

    “The CEBAF accelerator commissioning and achievement of the design energy required hard work, patience and teamwork,” said Arne Freyberger, Jefferson Lab’s director of accelerator operations. “It’s just fantastic to watch it all come together, and the sense of accomplishment is palpable.”

    Once the upgrade is complete, CEBAF will become an unprecedented tool for the study of the basic building blocks of the visible universe. It will be able to deliver 11 GeV electrons into its original experimental areas, Halls A, B and C for experiments. The full-energy, 12 GeV electrons are now being provided to the Experimental Hall D complex to initiate studies of the force that glues matter together. In Hall D, scientists hope to produce new particles, called hybrid mesons. Hybrid mesons are made of quarks bound together by the strong force, the same building blocks of protons and neutrons, but in hybrid mesons, this force is somewhat modified. It’s hoped that observing these hybrid mesons and revealing their properties will offer a new window into the inner workings of matter.

    “This kind of science explores the most fundamental mysteries: Why are we here? Why is it that one particular combination of quarks and forces takes on that material property, while a different combination of quarks and forces makes up the human body?” Lung said. “One particularly compelling question that scientists have had, is why do we always find quarks bound together in two and threes, but never alone? We will have an entirely unique facility designed to answer the question.”

    Jefferson Lab is a world-leading nuclear physics research laboratory devoted to the study of the building blocks of matter inside the atom’s nucleus – quarks and gluons – that make up 99 percent of the mass of our visible universe. Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

    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, visit science.energy.gov.

    See the full article here .

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    Thomas Jefferson National Accelerator Facility is managed by Jefferson Science Associates, LLC for the U.S. Department of Energy

     
  • richardmitnick 10:59 am on May 20, 2015 Permalink | Reply
    Tags: , , , , JLab,   

    From Nature: “Billion-dollar particle collider gets thumbs up” 

    Nature Mag
    Nature

    19 May 2015
    Edwin Cartlidge

    1
    Brookhaven National Laboratory in New York is a potential host for the Electron-Ion Collider. Brookhaven National Laboratory/CC BY-NC-ND 2.0

    A machine that would allow scientists to peer deeper than ever before into the atomic nucleus is a big step closer to being built. A high-level panel of nuclear physicists is expected to endorse the proposed Electron-Ion Collider (EIC) in a report scheduled for publication by October. It is unclear how long construction would take.

    The panel is the [DOE] Nuclear Science Advisory Committee, or NSAC, which produces regular ten-year plans for the US Department of Energy (DOE) and the National Science Foundation. Its latest plan is still being finalized, but NSAC’s long-range planning group “strongly recommended” construction of the EIC at a meeting last month, says NSAC member Abhay Deshpande, a nuclear physicist at Stony Brook University in New York. The EIC will almost certainly be formally endorsed in the NSAC report, he says. It must then be approved by the DOE, but most projects backed by the expert panel have come to fruition, he says.

    The collider would allow unprecedented insights into how protons and neutrons are built up from quarks and the particles that act between them, known as gluons.

    The current leading facilities for studying quark–gluon matter are the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, and the Large Hadron Collider at CERN, Europe’s particle-physics laboratory near Geneva, Switzerland.

    BNL RHIC Campus
    BNL RHIC
    BNL RHIC

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    CERN LHC

    These facilities smash protons and heavy ions together to recreate the energetic conditions of the early Universe, when quarks and gluons existed as a plasma rather than in atomic nuclei. The EIC would collide point-like electrons with either protons or heavy ions, generating collisions that have a similarly high energy but are more precise and so can be used to study subatomic particles in detail.

    In particular, the EIC would be ideal for studying an exotic state of matter that is made up entirely of gluons. The machine should also solve a puzzle about the proton that has baffled physicists for nearly 30 years. The proton has a quantum-mechanical property called spin, but, strangely, the spins of its three constituent quarks add up to only about one-third of its own spin. The EIC would determine what makes up the difference: options include the spin of the proton’s gluons, the angular momentum of its quarks or of the gluons from their orbital motion, or a mixture of all three.

    “Until we have the EIC, there are huge areas of nuclear physics that we are not going to make progress in,” says Donald Geesaman, a nuclear physicist at Argonne National Laboratory in Illinois, and the chair of NSAC.

    The machine would not be built from scratch. One option is to add an electron-beam facility to RHIC — a plan that is estimated to cost about US$1 billion and would depend on some as-yet-unproven technologies. Another is to add an ion accelerator and new collider rings to the Continuous Electron Beam Accelerator Facility [CEBAF] at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia, which would cost about $1.5 billion.

    Jlab CEBAF
    CEBAF at JLab

    Deshpande hopes that the DOE will give the collider the thumbs up within a year of the NSAC plan’s publication. Two or three more years would be needed to finalize the competing bids and choose one, meaning that construction could start in about 2020 and be completed five years later, he says.

    Others say that this outlook is too rosy. The 2008 financial crisis led to a drop in science funding that forced NSAC to review its 2007 ten-year plan. A specially formed subcommittee concluded in 2013 that RHIC would have to shut down if funding for the DOE’s Office of Nuclear Physics remained flat over the following five years. In fact, those funds have grown slightly, keeping RHIC in business, but the scare led to a more cautious approach this time around, says Geesaman. He points out that when the DOE and the National Science Foundation commissioned the ten-year plan, they specified that NSAC should consider what US physicists could achieve if funding remained flat, as well as how much support they would need to maintain a “world-leadership position”.

    Robert McKeown, deputy director for science at the Jefferson lab, thinks that limited funds might delay the start up of the EIC until at least 2030. And Michael Lubell, director of public affairs at the American Physical Society, questions whether it is feasible for the EIC to be built by the United States alone. He notes that the $1.5-billion Long-Baseline Neutrino Experiment became an international project [DUNE managed by FNAL] after a slimmed-down $600-million version failed to pass scientific muster. “It is hard to see how to do this unless you get international buy-in,” he says.

    Deshpande thinks that the United States can go it alone. But he notes that collaborations at CERN and in China are also developing plans for electron–ion colliders and that the three groups are already exchanging ideas.

    See the full article here.

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 9:05 pm on December 3, 2014 Permalink | Reply
    Tags: , , , JLab   

    From Symmetry: “Searching for a dark light” 

    Symmetry

    December 03, 2014
    Manuel Gnida

    A new experiment at Jefferson Lab is on the hunt for dark photons, hypothetical messengers of an invisible universe.

    The matter we know accounts for less than 5 percent of the universe; the rest is filled with invisible dark matter and dark energy. Scientists working on a new experiment to be conducted at Thomas Jefferson National Accelerator Facility in Virginia hope to shed light on some of those cosmic unknowns.

    According to certain theories known as hidden-sector models, dark matter is thought to consist of particles that interact with regular matter through gravitation (which is why we know about it) but not through the electromagnetic, strong and weak fundamental forces (which is why it is hard to detect). Such dark matter would interact with regular matter and with itself through yet-to-be-discovered hidden-sector forces. Scientists believe that heavy photons—also called dark photons—might be mediators of such a dark force, just as regular photons are carriers of the electromagnetic force between normal charged particles.

    The Heavy Photon Search at Jefferson Lab will hunt for these dark, more massive cousins of light.

    “The heavy photon could be the key to a whole rich world with many new dark particles and forces,” says Rouven Essig, a Stony Brook University theoretical physicist who in recent years helped develop the theory for heavy-photon searches.

    Although the idea of heavy photons has been around for almost 30 years, it gained new interest just a few years ago when theorists suggested that it could explain why several experiments detected more high-energy positrons—the antimatter partners of electrons—than scientists had expected in the cosmic radiation of space. Data from the PAMELA satellite experiment; the AMS instrument aboard the International Space Station; the LAT experiment of the Fermi Gamma-ray Space Telescope and others have all reported finding an excess of positrons.

    INFN PAMELA
    INFN/PAMELA

    AMS 02
    AMS-02

    NASA Fermi LAT
    NASA/Fermi LAT

    NASA Fermi Telescope
    NASA/Fermi spacecraft

    “The positron excess could potentially stem from dark matter particles that annihilate each other,” Essig says. “However, the data suggest a new force between dark matter particles, with the heavy photon as its carrier.”

    Creating particles of dark light

    If heavy photons exist, researchers want to create them in the lab.

    Theoretically, a heavy photon can transform into what is known as a virtual photon—a short-lived fluctuation of electromagnetic energy with mass—and vice versa. This should happen only very rarely and for a very short time, but it still means that experiments that produce virtual photons could in principle also generate heavy photons. Producing enormous numbers of virtual photons may create detectable amounts of heavy ones.

    At Jefferson Lab’s Continuous Electron Beam Accelerator Facility, CEBAF, scientists will catapult electrons into a tungsten target, which will generate large numbers of virtual photons—and perhaps some heavy photons, too.

    Jlab CEBAF
    JLab/CEBAF

    “CEBAF provides a very stable, highly intense electron beam that is almost continuous,” says Jefferson Lab’s Stepan Stepanyan, one of three spokespersons for the international HPS collaboration, which includes more than 70 scientists. “It is a unique place for performing this experiment.”

    The virtual photons and potential heavy photons produced at CEBAF will go on to decay into pairs of electrons and positrons. A silicon detector placed right behind the target will then track the pairs’ flight paths, and an electromagnetic calorimeter will measure their energies. Researchers will use this information to reconstruct the exact location in which the electron-positron pair was produced and to determine the mass of the original photon that created the pair. Both are important data points for picking the heavy photons out of the bunch.

    The photon mass measured in the experiment matters because a heavy photon has a unique mass, whereas virtual photons appear with a broad range of masses. “The heavy photon would reveal itself as a sharp bump on top of a smooth background from the virtual photon decays,” says SLAC National Accelerator Laboratory’s John Jaros, another HPS spokesperson.

    The location in which the electron-positron pair was produced also matters because virtual photons decay almost instantaneously within the target, says Timothy Nelson, project lead for the silicon detector, which is being built at SLAC. Heavy photons could decay more slowly, after traveling beyond the target. So photons that decay outside the target can only be heavy ones. The HPS silicon detector’s unique ability to identify outside-of-target decays sets it apart from other experiments currently participating in a worldwide hunt for heavy photons.

    The HPS calorimeter, whose construction was led by researchers from the French Institut de Physique Nucléaire, the Italian Istituto Nazionale di Fisica Nucleare and Jefferson Lab, is currently being tested at Jefferson Lab, while scientists at SLAC plan to ship their detector early next year. The experiment is scheduled to begin in the spring of 2015.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:46 am on April 28, 2014 Permalink | Reply
    Tags: , JLab, , Symmetry Breaking Studies   

    From DOE Pulse: “Quarks in the looking glass” 

    pulse

    D.O.E. Pulse

    April 28, 2014
    Submitted by DOE’s Thomas Jefferson Accelerator Facility

    From matching wings on butterflies to the repeating six-point pattern of snowflakes, symmetries echo through nature, even down to the smallest building blocks of matter. Since the discovery of quarks, the building blocks of protons and neutrons, physicists have been exploiting those symmetries to study quarks’ intrinsic properties and to uncover what those properties can reveal about the physical laws that govern them.

    mirror
    Elementary particles behave differently in the mirror world. Graphic: Jefferson Lab

    A recent experiment carried out at DOE’s Jefferson Lab to study a rare instance of symmetry breaking in electron-quark scattering has provided a new determination of an intrinsic property of quarks that’s five times more precise than the previous measurement.

    The result has also set new limits, in a way complementary to high-energy colliders such as the Large Hadron Collider at CERN, for the energies that researchers would need to access physics beyond the Standard Model.

    LHC Grand Tunnel
    LHC

    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.

    The Standard Model is a well-tested theory that, excluding gravity, describes the subatomic particles and their interactions, and physicists believe that peering beyond the Standard Model may help resolve many unanswered questions about the origins and underlying framework of our universe.

    The experiment probed properties of the mirror symmetry of quarks. In mirror symmetry, the characteristics of an object remain the same even if that object is flipped as though it were reflected in a mirror.

    The mirror symmetry of quarks can be probed by gauging their interactions with other particles through fundamental forces. Three of the four forces that mediate the interactions of quarks with other particles – gravity, electromagnetism and the strong force – are mirror-symmetric. However, the weak force – the fourth force – is not. That means that the intrinsic characteristics of quarks that determine how they interact through the weak force (called the weak couplings) are different from, for example, the electric charge for the electromagnetic force, the color charge for the strong force, and the mass for gravity.

    In Jefferson Lab’s Experimental Hall A, experimenters measured the breaking of the mirror symmetry of quarks through the process of deep-inelastic scattering. A 6.067 GeV beam of electrons was sent into deuterium nuclei, the nuclei of an isotope of hydrogen that contain one neutron and one proton each (and thus an equal number of up and down quarks).

    “When it’s deep-inelastic scattering, the momentum carried by the electron goes inside the nucleon and breaks it apart,” said Xiaochao Zheng, an associate professor of physics at the University of Virginia and a spokesperson for the collaboration that conducted the experiment.

    To produce the effect of viewing the quarks through a mirror, half of the electrons sent into the deuterium were set to spin along the direction of their travel (like a right-handed screw), and the other half were set to spin in the opposite direction. About 170,000 million electrons that interacted with quarks in the nuclei through both the electromagnetic and the weak forces over a two-month period of running were identified in two High Resolution Spectrometers.

    “This is called an inclusive measurement, but that just means that you only measure the scattered electrons. So, we used both spectrometers, but each detecting electrons independently from the other. The challenging part is to identify the electrons as fast as they come,” Zheng said.

    The experimenters found an asymmetry, or difference, in the number of electrons that interacted with the target when they were spinning in one direction versus the other. This asymmetry is due to the weak force between the electron and quarks in the target. The weak force experienced by quarks has two components. One is analogous to electric charge and has been measured well in previous experiments. The other component, related to the spin of the quark, has been clearly isolated for the first time in the Jefferson Lab experiment.

    Specifically, the present result led to a determination of the effective electron-quark weak coupling combination 2C2u – C2d that is five times more precise than previously determined. This particular coupling describes how much of the mirror-symmetry breaking in the electron-quark interaction originates from quarks’ spin preference in the weak interaction. The new result is the first to show that this combination is non-zero, as predicted by the Standard Model.

    The last experiment to access this coupling combination was E122 at DOE’s Stanford Linear Accelerator Center (now SLAC National Accelerator Laboratory). Data from that experiment were used to establish the newly theorized Standard Model more than 30 years ago.

    SLAC Campus
    SLAC

    The good agreement between the new 2C2u – C2d result and the Standard Model also indicates that experimenters must reach higher energy limits in order to potentially find new interactions beyond the Standard Model with respect to the violation of mirror symmetry due to the spin of the quarks. The new limits, 5.8 TeV and 4.6 TeV, are within reach of the Large Hadron Collider at CERN, but the spin feature provided by this experiment cannot be identified cleanly in collider experiments.

    In the meantime, the researchers plan to extend this experiment in the next era of research at Jefferson Lab. In a bid to further refine the knowledge of quarks’ mirror-symmetry breaking, experimenters will use Jefferson Lab’s upgraded accelerator to nearly double the energy of the electron beam, reducing their experimental errors and improving the precision of the measurement by five to ten times the current value. The experiment will be scheduled following completion of the upgrade in 2017.

    The experiment was funded by the DOE Office of Science, the National Science Foundation Division of Physics and the Jeffress Memorial Trust, as well as with support provided to individual researchers by their home institutions. Nearly 100 researchers from more than 30 institutions collaborated on the experiment, including two DOE National Labs, Jefferson Lab and Argonne National Lab. The result was published in the Feb. 6 edition of Nature.

    See the full article here.

    DOE Pulse highlights work being done at the Department of Energy’s national laboratories. DOE’s laboratories house world-class facilities where more than 30,000 scientists and engineers perform cutting-edge research spanning DOE’s science, energy, National security and environmental quality missions. DOE Pulse is distributed twice each month.

    DOE Banner


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  • richardmitnick 9:06 am on February 11, 2014 Permalink | Reply
    Tags: , , , JLab, ,   

    From Symmetry: “Quarks in the looking glass” 

    February 10, 2014
    Kandice Carter

    A recent experiment at Jefferson Lab probed the mirror symmetry of quarks, determining that one of their intrinsic properties is non-zero—as predicted by the Standard Model.
    sm
    Standard Model of Particle Physics

    From matching wings on butterflies to the repeating six-point pattern of snowflakes, symmetries echo through nature, even down to the smallest building blocks of matter. Since the discovery of quarks, the building blocks of protons and neutrons, physicists have been exploiting those symmetries to study quarks’ intrinsic properties and to uncover what those properties can reveal about the physical laws that govern them.

    A recent experiment carried out at Jefferson Lab has provided a new determination of an intrinsic property of quarks that’s five times more precise than the previous measurement.

    jlab
    Courtesy of Jefferson Lab

    The result has also set new limits, in a way complementary to such as the Large Hadron Collider at CERN, for the energies that researchers would need to access physics beyond the Standard Model. The Standard Model is a well-tested theory that, excluding gravity, describes the subatomic particles and their interactions, and physicists believe that peering beyond the Standard Model may help resolve many unanswered questions about the origins and underlying framework of our universe. The result was published in the February 6 edition of Nature.

    CERN

    CERN LHC New
    LHC

    The experiment probed properties of the mirror symmetry of quarks. In mirror symmetry, the characteristics of an object remain the same even if that object is flipped as though it were reflected in a mirror.

    The mirror symmetry of quarks can be probed by gauging their interactions with other particles through fundamental forces. Three of the four forces that mediate the interactions of quarks with other particles—gravity, electromagnetism and the strong force—are mirror-symmetric. However, the weak force—the fourth force—is not. That means that the intrinsic characteristics of quarks that determine how they interact through the weak force (called the weak couplings) are different from, for example, the electric charge for the electromagnetic force, the color charge for the strong force, and the mass for gravity.

    jlab
    Info-Graphic by: Jefferson Lab

    In Jefferson Lab’s Experimental Hall A, experimenters measured the breaking of the mirror symmetry of quarks through the process of deep-inelastic scattering. A 6.067 billion-electronvolt beam of electrons was sent into deuterium nuclei, the nuclei of an isotope of hydrogen that contain one neutron and one proton each (and thus an equal number of up and down quarks).

    “When it’s deep-inelastic scattering, the momentum carried by the electron goes inside the nucleon and breaks it apart,” says Xiaochao Zheng, an associate professor of physics at the University of Virginia and a spokesperson for the collaboration that conducted the experiment.

    To produce the effect of viewing the quarks through a mirror, half of the electrons sent into the deuterium were set to spin along the direction of their travel (like a right-handed screw), and the other half were set to spin in the opposite direction. Researchers identified about 170,000 million electrons that interacted with quarks in the nuclei through both the electromagnetic and the weak forces over a two-month period of running.

    “This is called an inclusive measurement, but that just means that you only measure the scattered electrons. So, we used both spectrometers, but each detecting electrons independently from the other. The challenging part is to identify the electrons as fast as they come,” Zheng says.

    The experimenters found an asymmetry, or difference, in the number of electrons that interacted with the target when they were spinning in one direction versus the other. This asymmetry is due to the weak force between the electron and quarks in the target. The weak force experienced by quarks has two components. One is analogous to electric charge and has been measured well in previous experiments. The other component, related to the spin of the quark, has been clearly isolated for the first time in the Jefferson Lab experiment.

    Specifically, the present result led to a determination of the effective electron-quark weak coupling combination 2C2u–C2d that is five times more precise than previously determined. This particular coupling describes how much of the mirror-symmetry breaking in the electron-quark interaction originates from quarks’ spin preference in the weak interaction. The new result is the first to show that this combination is non-zero, as predicted by the Standard Model.

    The last experiment to access this coupling combination was E122 at SLAC National Accelerator Laboratory. Data from that experiment were used to establish the newly theorized Standard Model more than 30 years ago.

    The good agreement between the new 2C2u–C2d result and the Standard Model also indicates that experimenters must reach higher energy limits in order to potentially find new interactions beyond the Standard Model with respect to the violation of mirror symmetry due to the spin of the quarks. The new limits, 5.8 and 4.6 trillion electronvolts, are within reach of the Large Hadron Collider at CERN, but the spin feature provided by this experiment cannot be identified cleanly in collider experiments.

    In the meantime, the researchers plan to extend this experiment in the next era of research at Jefferson Lab. In a bid to further refine the knowledge of quarks’ mirror-symmetry breaking, experimenters will use Jefferson Lab’s upgraded accelerator to nearly double the energy of the electron beam, reducing their experimental errors and improving the precision of the measurement by five to 10 times the current value. The experiment will be scheduled following completion of the upgrade in 2017.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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  • richardmitnick 11:52 am on January 17, 2014 Permalink | Reply
    Tags: , , JLab, , Spectrometers   

    From Fermilab: “Fermilab breaks ground on coil fabrication for Jefferson Lab collaboration” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Friday, Jan. 17, 2014
    Sarah Witman

    There is perhaps no greater challenge, mentally, than taking on a project that has been attempted previously but not successfully completed.

    This is the position a team of Fermilab engineers and physicists found themselves in more than a year ago, when Jefferson Lab, based in Virginia, came to Fermilab for help on a project: fabricating magnet coils for an upgrade to its CEBAF Large Acceptance Spectrometer (CLAS) experiment.

    It turned out to be a good move. In late November, a Magnet Systems Department fabrication team in the Technical Division successfully wound a full-size coil, called a practice coil, of the type to be installed in the new torus magnet for the upgrade of Jefferson Lab’s CLAS detector. Jefferson Lab’s upgraded facilities will provide scientists with unprecedented precision and reach for studies of atomic nuclei.

    coil
    The Magnet Systems Department recently successfully completed a prototype torus magnet coil for the Jefferson Lab CLAS12 upgrade. They devised a relatively inexpensive system, seen here, for winding the 2,500-pound coil. While the price of a standard coil-winding table that can hold a 4,000-pound fixture is $190,000, the Fermilab team built an adequate system for less than $10,000. One layer of coil, sitting at the winding fixture with a 12-foot-diameter cable spool installed above the fixture, and the second spool on the tensioner, is almost completely wound. Photo: Douglas Howard, TD

    “Now we can say we can definitely do this job,” said Fermilab engineer Sasha Makarov. “It seems like Jefferson Lab is very satisfied with our achievement.”

    See the full article here.

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.


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  • richardmitnick 6:06 pm on November 18, 2013 Permalink | Reply
    Tags: , , JLab, ,   

    From Symmetry: “Connecting the visible universe with dark matter” 

    November 18, 2013

    Does the visible photon have a counterpart, a dark photon, that interacts with the components of dark matter?

    Kandice Carter

    For thousands of years, humanity has relied on light to reveal the mysteries of our universe, whether it’s by observing the light given off by brightly burning stars or by shining light on the very small with microscopes.

    Yet, according to recent evidence, scientists think that only about 5 percent of our universe is made of visible matter—ordinary atoms that make up nearly everything we can see, touch and feel. The other 95 percent is composed of the so-called dark sector, which includes dark matter and dark energy. These are described as “dark” because we observe their effects on other objects rather than by seeing them directly. Now, to study the dark, scientists are turning to what they know about light, and they are pointing to a recently successful test of experimental equipment that suggests an exploration of the dark sector may be possible at Jefferson Lab.

    Dark light

    darklight
    Illustration by Sandbox Studio, Chicago

    We know that the particles of light, photons, interact with visible matter and its building blocks—protons, neutrons and electrons. Perhaps the same is true for dark matter. In other words, does the visible photon have a counterpart, a dark photon, that interacts with the components of dark matter?

    The DarkLight collaboration is hoping to answer that question. Peter Fisher and Richard Milner, professors at the Massachusetts Institute of Technology, serve as spokespersons for the DarkLight collaboration. Fisher was recently appointed head of the MIT physics department, and Milner is director for the institute’s Laboratory of Nuclear Science.

    In a recent interview, Milner said that the dark photon may bridge the dark and light sectors of our universe.

    “Such particles are motivated by the assumption that dark matter exists and that it must somehow couple to the standard matter in the universe. And these dark photons kind of straightforwardly could do that,” he explains.

    According to theory, the dark photon is very similar to the light photon, except that it has mass and interacts with dark matter. The dark photon is sometimes referred to as a heavy photon or as a particle dubbed the A’ (pronounced “A prime”). If the dark photon also interacts with ordinary matter, it may be coaxed out of hiding under just the right conditions. In fact, Milner says that scientists may have already caught glimpses of the effects of dark photons in data from particle physics and astrophysics experiments.

    Hints of dark photons in data past

    For instance, dark photons may play a role in explaining the data in the Muon g-2 experiment (pronounced “Moo-on g minus two experiment”) that was conducted at Brookhaven National Laboratory in 2001. Muons are particles that can be thought of as heavier cousins of electrons.

    The Muon g-2 experiment sought to measure a characteristic of the muon related to its magnetic field. In simplistic terms, an item’s magnetic moment quantifies the strength of its reaction to a magnetic field. The muon has a magnetic moment, but, unlike your typical chunk of steel, the muon’s magnetic moment is altered by its tiny size—this alteration is captured in the muon’s so-called “anomalous magnetic moment.” When the Muon g-2 collaboration measured the muon’s anomalous magnetic moment, its collaborators were surprised to find that the number they they measured didn’t match the number they expected.

    “If this is real, such a discrepancy could be explained by a dark photon of the type and mass that DarkLight is searching for,” Milner says.

    Other evidence of dark photons may be found in astrophysics.

    When a measurement was made of high-energy electron–positron pairs in outer space, there were more than could be explained by production from cosmic rays, suggesting that something else, such as dark photons, produces extra pairs.

    “Also, there are indications from the center of our galaxy that there is radiation which might be consistent with the dark photon,” Milner adds.

    A challenging experiment

    If dark photons are giving rise to these observed phenomena, it means that they do interact with visible matter, if ever so rarely. It also means that the effect should be reproducible and measurable by experimenters.

    “This dark photon that we expect could be seen by emission from a charged particle beam, like an electron beam. So an electron beam can radiate such a dark photon,” Milner explains. “So, we looked around, and the world’s most powerful electron beam is at the Jefferson Lab Free-Electron Laser. It has about 1 megawatt of power in the beam. And so that’s how we arrived at Jefferson Lab; it’s absolutely unique in the world.”

    The scientists drafted a proposal that calls for aiming the beam at the protons in a target of hydrogen gas. MIT theorist Jesse Thaler, whose group has carried out important calculations for DarkLight, proposed the name for the experiment, based on the method that will be used to carry it out (DarkLight: Detecting a Resonance Kinematically with Electrons Incident on a Gaseous Hydrogen Target).

    The experimenters chose hydrogen, because its atoms consist of just one proton with an orbiting electron. When the electrons from the accelerator strike the protons in the hydrogen, they’ll knock the protons out of the target.

    “So if we do it at sufficiently low energies, we know the final state is simple—it’s just the scattered electron, the proton and the electron–positron pair, which could come from this decay of the dark photon,” Milner explains.

    The experiment was approved on the condition that the collaboration could show that they were up to the technical challenges of conducting it. Milner says the main challenge was to prove that the accelerator operators could get an electron beam through the narrow hydrogen target. Even though the electrons in the beam would have low energies, the beam would have a lot of them, amounting to 1 megawatt of power. That much power would destroy any container used to hold the hydrogen gas.

    The experimenters decided that the gas would be pumped into a narrow pipe. The electrons would then be threaded into that same narrow pipe. At its narrowest, the pipe would need to be about 2 millimeters wide and 5 centimeters long, which is roughly the size of a round coffee stirrer.

    “We decided that we really needed to do a test with a beam. So, we basically built a system, a test target system that had basically a mock-up of apertures, 2-millimeter-, 4-millimeter- and 6-millimeter-diameter apertures, in an aluminum block. And we brought it to Jefferson Lab about a year ago. And in late July, we had a test,” he says.

    jlab
    Jefferson Lab laser accelerator operators threaded an electron beam through a small tube the size of a coffee stirrer inside this apparatus to show that the DarkLight experiment was possible. DarkLight will search for dark photons, which are particles that interact with both dark matter and visible matter. Courtesy of: Jefferson Lab

    Threading the coffee stirrer

    The staff at MIT-Bates Research and Engineering Center designed, constructed and delivered the test target assembly. The Jefferson Lab accelerator operators and a team from the DarkLight collaboration attempted to thread the electron beam through the narrow pipes in the aluminum block, successfully threading the beam through the 6-millimeter, then the 4-millimeter, and finally the 2-millimeter mock targets. What’s more, the electrons in the beam passed through the pipes cleanly. In the case of the smallest aperture, 2 millimeter, the operators threaded the electrons through the pipe continuously over a period of seven hours; in that time, only three electrons were lost as they struck the walls of the pipe for every million that passed cleanly through.

    “So, it’s a very powerful beam, it’s a very bright beam, but it’s also a very clean beam,” Milner says.

    The DarkLight collaboration recently published the results of the successful tests in Physical Review Letters.

    With this successful test, the DarkLight experiment has been approved for running. Milner says the collaboration has a lot of work ahead of it before it can run the experiment, including building the detectors that will be used to capture the protons, electrons and electron–positron pairs, and finalizing the target.

    In the meantime, there are also other hunts for dark photons that are preparing to run at Jefferson Lab. Two of these experiments will be powered by the same accelerator. The Heavy Photon Search is preparing to run in Jefferson Lab’s Experimental Hall B, and the APEX experiment will be carried out in Experimental Hall A.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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