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  • richardmitnick 2:51 pm on June 26, 2020 Permalink | Reply
    Tags: "New Research Deepens Mystery of Particle Generation in Proton Collisions", , , BNL, , , , , RHICf   

    From Brookhaven National Lab: “New Research Deepens Mystery of Particle Generation in Proton Collisions” 

    From Brookhaven National Lab

    June 23, 2020

    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    ____________________________________
    The following news release was issued by the RHICf collaboration. The RHICf experiment is installed in the “forward” direction (along the beamline) in the same particle interaction region as the STAR detector [below] at the Relativistic Heavy Ion Collider (RHIC) [below], a DOE Office of Science user facility for nuclear physics research at Brookhaven National Laboratory. The RHICf experiment collected data from RHIC’s polarized proton collisions to explore further details of asymmetries observed in collisions at RHIC—particularly a preference for certain particles to emerge from these spin-polarized collisions in a particular direction. This new result adds to the puzzling story of what causes this “transverse spin asymmetry”—an open question for physicists since the 1970s. These and other results from RHIC’s polarized proton collisions will eventually contribute to solving this question. For more information about research at RHIC, contact Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov.
    ____________________________________

    1
    The RHICf experiment is installed in the “forward” direction (along the beamline) in the same particle interaction region as the STAR detector at the Relativistic Heavy Ion Collider (RHIC), a DOE Office of Science user facility for nuclear physics research at Brookhaven National Laboratory.

    A group of researchers including scientists from the RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Nagoya University, and the Japan Atomic Energy Agency (JAEA) used the spin-polarized Relativistic Heavy Ion Collider (RHIC) [below]—a DOE Office of Science user facility for nuclear physics research at Brookhaven National Laboratory in the United States—to show that, in polarized proton-proton collisions, neutral pions emitted in the very forward area of collisions—where direct interactions involving quarks and gluons are not applicable—still have a large degree of left-right asymmetry. This finding suggests that the previous consensus regarding the generation of particles in such collisions needs to be reevaluated.

    Understanding the mechanism through which particles are created in collisions involving protons has relevance for understanding cosmic ray showers, where particles entering Earth’s atmosphere from outer space create particle “showers” that help us learn about astronomical phenomena that take place in the extreme environment of the universe. However, it is very difficult to study the details of how particles are created, as the force that binds protons in the nucleus and that bind quarks and gluons into protons—the strong interaction or nuclear force—is very strong compared to other forces such as the electromagnetic force and gravity. One avenue for exploring these challenging questions has involved an attribute of protons called “spin,” which can be understood by analogy to the way a toy top rotates on its axis. The spin of protons can be artificially aligned in a process that is called “polarization.”

    In the 1970s, accelerator experiments at Argonne National Laboratory in the United States revealed that the pions generated toward the front of collisions involving polarized protons had large left-right asymmetry. The energy of the polarized protons used in these experiments was about 10 billion electron volts (GeV). Experiments at higher energies—including one at 200 GeV using the polarized proton beam at Fermi National Accelerator Laboratory (FNAL) in the United States and at RHIC at Brookhaven National Laboratory (BNL) in the United States, where two beams of 100 GeV protons moving in opposite directions were collided—showed that the left-right asymmetry persisted even with high-energy polarized protons. A consensus emerged that this asymmetry was caused by direct interactions among the quarks and gluons in the protons, based on a theory called perturbative quantum chromodynamics (QCD).

    1
    Understanding the mechanism through which particles are created in collisions involving protons like those at RHIC has relevance for understanding cosmic ray showers created by particles entering Earth’s atmosphere. (Image credit: Simon Swordy (U. Chicago), NASA)

    However, with additional experiments at RHIC, findings began to emerge that challenged the consensus. According to Yuji Goto, one of the authors of the current work, “At the energy of RHIC, quarks and gluons are scattered, and various particles are generated in the form of a jet. When the left-right asymmetry of the jet generated forward of the collision position at RHIC was examined, it was found that, contrary to expectations, the overall jet and the pions contained in the jet did not show a left-right asymmetry. This suggested that the cause of the left-right asymmetry was not the direct scattering of quarks and gluons.”

    In order to further investigate, the researchers conducted experiments, published in Physical Review Letters, where they used an electromagnetic calorimeter detector previously used in the Large Hadron Collider at CERN—known as the LHCf experiment there and the RHICf experiment at RHIC—to take a detailed look at the gamma rays generated by pion decays at the very forward region of the collision. They found, however, that the left-right asymmetry in neutral pions persists even in that very narrow area.

    CERN LHCf

    BNL RHICf detector

    More information on the RHICf experiment is available at http://crportal.isee.nagoya-u.ac.jp/RHICf/.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 10:56 am on May 29, 2020 Permalink | Reply
    Tags: (EIC)-Electron-Ion Collider at BNL, , BNL, , , ,   

    From Brookhaven National Lab: “EIC R&D Yields Energy-saving Accelerator Innovations” 

    From Brookhaven National Lab

    May 22, 2020
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    1
    Vladimir Litvinenko, Thomas Roser, and Maria Chamizo-Llatas co-authored a paper describing a design for a possible future high-energy electron-positron collider in which an energy-recovery linac (ERL) recaptures and recycles both the particles and their energy.

    As physicists developed plans for building an Electron-Ion Collider (EIC)—a next-generation nuclear physics facility to be built at the U.S. Department of Energy’s Brookhaven National Laboratory for nuclear physics research—they explored various options for accelerating the beams of electrons. One approach, developed by scientists at Brookhaven Lab and Stony Brook University, was to use an energy-recovery linear accelerator (ERL). The ERL would bring the electrons up to the energy needed to probe the inner structure of protons and atomic nuclei, and then decelerate the electrons and reuse most of their energy. The R&D to develop the innovative ERL may end up having a major impact in a different area of physics—high-energy particle physics, where the power needs make its energy-saving features particularly attractive.

    “The power consumption of scientific instruments for particle physics experiments has steadily increased. To perform sustainable research, physicists are investigating ways to reduce that power consumption,” said Thomas Roser, head of Brookhaven Lab’s Collider-Accelerator Department, one of the scientists developing the ERL approach.

    In a paper just published in the journal Physics Letters B, the authors describe how their innovations could tame the power requirements of an electron-positron (e-e+) collider—a next-generation high-energy particle physics research facility under discussion for possible future construction in Europe.

    Colliding electrons and positrons

    The particle physics community is in the early stages of planning for a possible future electron-positron collider, including discussing various designs and locations. In each of these setups, the facility would bring beams of negatively charged electrons (e-) into collisions with their positively charged antimatter counterparts, known as positrons (e+), to conduct precision studies of the properties of the Higgs boson. That’s the particle discovered at the Large Hadron Collider (LHC) in Europe in 2012 that is responsible for imparting mass to most fundamental particles in the Standard Model of particle physics.

    “Learning more about the Higgs particle’s properties and interactions with other particles would help scientists unravel the mechanism behind this important foundation of how our universe works, and possibly uncover discrepancies that point to the existence of new particles or ‘new physics,’” said Brookhaven physicist Maria Chamizo-Llatas, a co-author on the paper.

    2
    Possible layout of an energy-recovery linac (ERL) electron-positron collider. Beams of electrons and positrons would each be accelerated in stages during four passes through two superconducting linacs, moving in opposite directions through the 100-kilometer-circumference ring after each acceleration pass. When the particles reach maximum energy (250 billion electron volts, or GeV, as shown on the inset graph) they would be brought into collision in one of the detectors (D1, D2). After collisions, smashed beams would be decelerated and cooled in low-energy (2 GeV) accelerator rings before repeating the acceleration-collision-deceleration process over and over again.

    One of the possible designs is a “storage ring” 100-kilometers in circumference based at Europe’s CERN laboratory (home to the 27-kilometer circular LHC). Beams of electrons and positrons would circulate through the storage ring continuously and collide repeatedly to produce the desired data. An alternate design would consist of two large linear accelerators that produce straight-line, head-on smashups.

    CERN FCC Future Circular Collider details of proposed 100km-diameter successor to LHC

    Power requirements for both of these setups are approaching hundreds of megawatts, Roser said—enough energy to power hundreds of thousands of homes.

    In a storage ring, Roser noted, lots of energy gets lost as “synchrotron” radiation, a type of energy emitted by charged particles as they change direction moving around the circle (picture the way water sprays off a wet towel if you swirl it around above your head). “The higher the energy, the greater the synchrotron energy loss,” Roser said—and the greater the need to make up that loss by adding more energy to keep particles colliding.

    In a collider using linear accelerators, no synchrotron radiation is emitted. But the used beams are discarded after a single pass through the accelerator. That means that the beam energy, and also all the beam particles, are lost. More energy is needed to accelerate fresh particle beams over and over.


    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan

    The Brookhaven and Stony Brook physicists say their energy-recovery and beam-recycling ERL components could solve key problems of both alternate designs. As described in the new paper, it would cut the electric power needed to operate the 100-km ring-shaped facility under discussion in Europe to one third of what would be required without an ERL. And, by refreshing particle beams while recovering and reusing their energy, it would eliminate the need to dump and replace beams while still allowing single-pass collisions of tightly packed particles for maximum physics impact.

    Reusing energy and recycling beams

    The ERL would be made of superconducting radiofrequency (SRF) cavities, and act as “a perpetuum-mobile of some kind invented in 1960s by Maury Tigner at Cornell University,” explained Vladimir Litvinenko, a professor of physics at Stony Brook University with a joint appointment at Brookhaven Lab. “The main advantage of SRF cavities is that they consume very little energy while operating. They are perfectly suited to accelerate new particles by taking energy back from used particles,” he explained.

    For an e-e+ collider, a multi-pass ERL would accelerate both sets of particles in stages to higher and higher energy each time they pass through the SRF linear accelerator. After each stage of acceleration, the particles would zip through a 100-kilometer ring-shaped tunnel back to the linear accelerator for the next stage of acceleration; electrons moving in one direction and positrons going the other way. Having the particles travel around such a large circular path helps to reduce the energy lost as synchrotron radiation.

    “After colliding at the top energy, both electrons and positrons would give their energy back by passing through the same accelerator but in decelerating fashion,” Litvinenko said. “During deceleration, the particles’ energy is captured in the SRF cavities to be used for accelerating the next batch of particles.”

    Importantly, not only the energy but also the particles themselves would be recycled after the collisions. Additional cooling components would ensure that the particles stay tightly packed to keep collision rates high but power requirements relatively low.

    “By taming the need for power and reusing particles in an e-e+ collider, our design would allow scientists to perform cutting-edge research in a sustainable way,” Roser said.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 8:10 am on April 24, 2020 Permalink | Reply
    Tags: "New Cathode Material Locks In Oxygen", , BNL, , Lithium-ion batteries power some of the newest and most prevalent technologies in society., , Preventing battery failure from oxygen release.   

    From Brookhaven National Lab: “New Cathode Material Locks In Oxygen” 

    From Brookhaven National Lab

    April 22, 2020
    Stephanie Kossman
    skossman@bnl.gov

    Scientists synthesized an energy-dense cathode material that has a continuous gradient of lithium concentration, preventing battery failure from oxygen release.

    1
    NSLS-II scientists Adrian Hunt (left) and Iradwikanari Waluyo (right) at the IOS beamline, where part of the research was conducted.

    From smartphones to electric vehicles, lithium-ion batteries power some of the newest and most prevalent technologies in society. That’s why scientists are working to make these batteries more powerful, more reliable, and longer lasting via new cathode materials.

    Choosing more energy-dense materials to build a cathode can solve some of the current challenges, but it often comes with a trade-off, such as gaining battery power in exchange for stability. But now, researchers at the Massachusetts Institute of Technology (MIT) have synthesized a new, energy-dense cathode material for lithium-ion batteries that also solves stability issues. They teamed up with scientists at the National Synchrotron Light Source II (NSLS-II) [below] and used facilities at the Center for Functional Nanomaterials (CFN) [below]—two U.S. Department of Energy (DOE) Office of Science User Facilities at DOE’s Brookhaven National Laboratory—to study chemical changes in the battery over time. The collaboration’s work is published in Nature Energy.

    “As you cycle lithium-ion batteries, they can change shape and start to fracture. All kinds of problems can arise that negatively impact how the battery functions,” said co-author Adrian Hunt, a scientist at the In situ and Operando Soft X-ray Spectroscopy (IOS) beamline at NSLS-II, where part of the research was conducted. “One of the causes of these problems is that cathode materials lose oxygen content near the surface. Our collaborators at MIT synthesized a material that locks in the structure of the cathode and its oxygen atoms, preventing the material from expanding and contracting.”

    Using molten salt materials and a novel synthesis method, the researchers at MIT developed a cathode with a continuous gradient of lithium in which the concentration is far greater at the material’s core, or “bulk,” than at its surface.

    “Traditional cathode materials have a uniform concentration of lithium from the surface through the bulk of the material, so, as the battery operates, oxygen is free to migrate to the surface and, eventually, it gets released, causing the battery to fail,” said co-author Iradwikanari Waluyo, lead beamline scientist at IOS. “The new cathode material, which is lithium-rich towards the bulk and less concentrated at the surface, essentially creates a shell that locks in oxygen, so it doesn’t migrate to the surface and it doesn’t get released.”

    Beyond having different concentrations of lithium at the surface and the bulk, a key part of this material’s successful design is the continuous gradient of lithium in between.

    “Typically, materials are not continuous,” Hunt said. “If you look down at a very small scale, there will be little grains between sections of the material where the atomic structure is slightly mismatched—like cracks in the material. Those places are problematic for conducting electricity and they also allow for oxygen movement.”

    Before the scientists at MIT could understand exactly how their new material was functioning, they needed to bring it to the IOS beamline at NSLS-II, where Waluyo and Hunt used ultrabright “soft” x-rays to reveal the chemical state of the battery in detail. Compared to hard x-rays, which are useful for penetrating heavy elements like metals, soft x-rays can detect lighter elements like oxygen and are more sensitive to their chemical states.

    “In addition to detecting oxygen, soft x-rays were critical for studying the different elemental concentrations and chemical states in the material from its surface to its bulk,” Waluyo said. “We can use different detection methods at IOS to tune the sensitivity of the technique to be surface sensitive or bulk sensitive. By looking at the electrons coming out of the sample we can study the surface, and by looking at the photons coming out the sample we can study the bulk.”

    IOS is also equipped with a silicon drift detector, which enables researchers at the beamline to differentiate between photons coming from specific elements in the sample. This increases the elemental sensitivity of the technique and eliminates distortions in the data.

    “You would not be able to do these kinds of measurements at a standard soft x-ray beamline,” Hunt said. “Most beamlines collect all the photons that come from the sample and you can’t tell the difference between them.”

    In addition to NSLS-II, the researchers also leveraged one of the seven facilities at the Center for Functional Nanomaterials (CFN), another DOE Office of Science User Facility at Brookhaven Lab. CFN’s electron microscopy (EM) facility helped the scientists understand the lithium elemental gradient profile across the novel cathode particles.

    “The researchers used our operando scanning transmission electron microscope—one of five state-of-the-art transmission electron microscopes in our EM facility,” said Kim Kisslinger, an advanced technical associate at CFN. “This particular microscope is equipped with the capability to perform electron energy loss spectroscopy, which offers high energy resolution and high precision for elemental mapping.”

    Moving forward, the researchers at MIT are continuing to collaborate with Waluyo and Hunt at NSLS-II’s IOS beamline.

    “They’re experts in making new materials,” Waluyo said. “They make a material and they know it works, but then we come in and show why it works. We look forward to our next experiment together.”

    “We are thrilled to work with the exceptional staff at Brookhaven National Laboratory and at the state-of-the-art IOS beamline at NSLS-II,” said MIT’s Ju Li, corresponding author of the paper. “The exciting discoveries today would not be possible without them, and we look forward to much more collaborative work in the future.”

    This study was supported in part by the National Science Foundation. Operations at NSLS-II and CFN are supported by DOE’s Office of Science.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 2:26 pm on March 18, 2020 Permalink | Reply
    Tags: "Three national laboratories achieve record magnetic field for accelerator focusing magnet", BNL, , , Magnets for the HL-LHC., The ingredient that sets these U.S.-produced magnets apart is niobium-tin.   

    From Fermi National Accelerator Lab: “Three national laboratories achieve record magnetic field for accelerator focusing magnet” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 18, 2020

    Media contacts

    Fermilab Office of Communication, media@fnal.gov, 630-840-3351
    Karen McNulty Walsh, Brookhaven National Laboratory, kmcnulty@bnl.gov, 631-344-8350, 917-699-0501
    Laurel Kellner, Lawrence Berkeley National Laboratory, lkellner@lbl.gov, 510-590-8034

    In a multiyear effort involving three national laboratories from across the United States, researchers have successfully built and tested a powerful new magnet based on an advanced superconducting material. The eight-ton device — about as long as a semi-truck trailer — set a record for the highest field strength ever recorded for an accelerator focusing magnet and raises the standard for magnets operating in high-energy particle colliders.

    The Department of Energy’s Fermilab, Brookhaven National Laboratory and Lawrence Berkeley National Laboratory designed, built and tested the new magnet, one of 16 they will provide for operation in the High-Luminosity Large Hadron Collider at CERN laboratory in Europe.

    The 16 magnets, along with another eight produced by CERN, serve as “optics” for charged particles: They will focus beams of protons into a tiny, infinitesimal spot as they approach collision inside two different particle detectors.

    The ingredient that sets these U.S.-produced magnets apart is niobium-tin – a superconducting material that produces strong magnetic fields. These will be the first niobium-tin quadrupole magnets ever to operate in a particle accelerator.

    Like the current Large Hadron Collider, its high-luminosity successor will smash together beams of protons cruising around the 17-mile ring at close to the speed of light. The HL-LHC will pack an additional punch: It will provide 10 times the collisions that are possible at the current LHC. With more collisions come more opportunities to discover new physics.

    And the machine’s new focusing magnets will help it achieve that leap in delivered luminosity.

    “We’ve demonstrated that this first quadrupole magnet behaves successfully and according to design, based on the multiyear development effort made possible by DOE investments in this new technology,” said Fermilab scientist Giorgio Apollinari, head of the U.S. Accelerator Upgrade Project, which leads the U.S.-based focusing-magnet project.

    “It’s a very cutting-edge magnet, really on the edge of magnet technology,” said Brookhaven National Laboratory scientist Kathleen Amm, the Brookhaven representative for the Accelerator Upgrade Project.

    What makes it successful is its impressive ability to focus.

    2
    This new magnet reached the highest field strength ever recorded for an accelerator focusing magnet. Designed and built by Fermilab, Brookhaven National Laboratory and Lawrence Berkeley National Laboratory, it will be the first niobium-tin quadrupole magnet ever to operate in a particle accelerator — in this case, the future High-Luminosity Large Hadron Collider at CERN. Photo: Dan Cheng, Lawrence Berkeley National Laboratory

    Focus, magnets, focus

    In circular colliders, two beams of particles race around the ring in opposite directions. An instant before they reach the collision point, each beam passes through a series of magnets that focus the particle beams into a tiny, infinitesimal spot, much the way lenses focus light rays to a point. Now packed as tightly with particles as the magnets can get them — smash! — the beams collide.

    The scientific fruitfulness of that smash depends on how dense the beam is. The more particles that are crowded into the collision point, the greater the chance of particle collisions.

    You get those tightly packed beams by sharpening the magnet’s focus. One way to do that is to widen the lens. Consider light:

    “If you try to focus the light from the sun using a magnifying glass at a small point, you want to have a more ‘powerful’ magnifying glass,” said Ian Pong, Berkeley Lab scientist and one of the control account managers.

    A larger magnifying glass focuses more of the sun’s rays than a smaller one. However, the light rays at the outer rim of the lens have to be bent more sharply in order to approach the same focal point.

    Or consider a group of archers shooting arrows at an apple: More arrows will stick if the archers shoot from above, below and either side of the apple than if they are stationed at one post, firing from the same position.

    The analog of the magnifying glass size and the archer array is the magnet’s aperture — the opening of the passageway the beam takes as it barrels through the magnet’s interior. If the particle beam is allowed to start wide before being focused, more particles will arrive at the intended focal point — the center of the particle detector.

    The U.S. team widened the LHC focusing magnet’s aperture to 150 millimeters, more than double the current aperture of 70 millimeters.

    But of course, a wider aperture isn’t enough. There is still the matter of actually focusing the beam, which means forcing a dramatic change in the beam’s size, from wide to narrow, by the time the beam reaches the collision point. And that requires an exceptionally strong magnet.

    “The magnet has to squeeze the beam more powerfully than the LHC’s present magnets in order to create the luminosity needed for the HL-LHC,” Apollinari said.

    To meet the demand, scientists designed and constructed a muscular focusing magnet, calculating that, at the required aperture, it would have to generate a field exceeding 11.4 teslas. This is up from the current 7.5-tesla field generated by the niobium-titanium-based LHC quadrupole magnets. (For accelerator experts: The HL-LHC integrated luminosity goal is 3,000 inverse femtobarns.)

    In January, the three-lab team’s first HL-LHC focusing magnet delivered above the goal performance, achieving an 11.5-tesla field and running continuously at this strength for five straight hours, just as it would operate when the High-Luminosity LHC starts up in 2027.

    “These magnets are the currently highest-field focusing magnets in accelerators as they exist today,” Amm said. “We’re really pushing to higher fields, which allows us to get to higher luminosities.”

    The new focusing magnet was a triumph, thanks to niobium-tin.

    Magnet makers: Three U.S. labs are building powerful magnets for the world’s largest powerful collider from Berkeley Lab on Vimeo.

    Niobium-tin for the win

    The focusing magnets in the current LHC are made with niobium-titanium, whose intrinsic performance limit is generally recognized to have been reached at 8 to 9 teslas in accelerator applications.

    The HL-LHC will need magnets with around 12 teslas, about 250,000 times stronger than the Earth’s magnetic field at its surface.

    “So what do you do? You need to go to a different conductor,” Apollinari said.

    Accelerator magnet experts have been experimenting with niobium-tin for decades. Electrical current coursing through a niobium-tin superconductor can generate magnetic fields of 12 teslas and higher — but only if the niobium and tin, once mixed and heat treated to become superconductive, can stay intact.

    “Once they’re reacted, it becomes a beautiful superconductor that can carry a lot of current, but then it also becomes brittle,” Apollinari said.

    Famously brittle.

    “If you bend it too much, even a little bit, once it’s a reacted material, it sounds like corn flakes,” Amm said. “You actually hear it break.”

    Over the years, scientists and engineers have figured out how to produce niobium-tin superconductor in a form that is useful. Guaranteeing that it would hold up as the star of an HL-LHC focusing magnet was another challenge altogether.

    Berkeley, Brookhaven and Fermilab experts made it happen. Their assembly process is a delicate, involved operation balancing niobium-tin’s fragility against the massive changes in temperature and pressure it undergoes as it becomes the primary player in a future collider magnet.

    The process starts with wires containing niobium filaments surrounding a tin core, provided by an outside manufacturer. The wires are then fabricated into cables at Berkeley in just the right way. The teams at Brookhaven and Fermilab then wind these cables into coils, careful to avoid deforming them excessively. They heat the coils in a furnace in three temperature stages, a treatment that takes more than a week. During heat treatment the tin reacts with the filaments to form the brittle niobium-tin.

    Having been reacted in the furnace, the niobium-tin is now at its most fragile, so it is handled with care as the team cures it, embedding it in a resin to become a solid, strong coil.

    That coil is now ready to serve as one of the focusing magnet’s four poles. The process takes several months for each pole before the full magnet can be assembled.

    “Because these coils are very powerful when they are energized, there is a lot of force trying to push the magnet apart,” Pong said. “Even if the magnet is not deforming, at the conductor level there will be a strain, to which niobium-tin’s performance is very sensitive. The management of the stress is very, very important for these high-field magnets.”

    Heat treating the magnet coils — one of the intermediate steps in the magnet’s assembly — is also a subtle science. Each of the four coils of an HL-LHC focusing magnet weighs about one ton and has to be heat-treated evenly — inside and out.

    “You have to control the temperature well. Otherwise the reaction will not give us the best performance,” Pong said. “It’s a bit like cooking. It’s not just to achieve the temperature in one part of the coil but in the entire coil, end to end, top to bottom, the whole thing.”

    And the four coils have to be aligned precisely with one another.

    “You need very high field precision, so we have to have very high precision in how they align these to get good magnetic-field uniformity, a good quadrupole field,” Amm said.

    The fine engineering that goes into the U.S. HL-LHC magnets has sharpened over decades, with a payoff that is energizing the particle accelerator community.

    “This will be the first use of niobium-tin in accelerator focusing magnets, so it will be pretty exciting to see such a complex and sophisticated technology get implemented into a real machine,” Amm said.

    “We were always carrying the weight of responsibility, the hope in the last 10, 20 years — and if you want to go further, 30, 40 years — focusing on these magnets, on conductor development, all the work,” Pong said. “Finally, we are coming to it, and we really want to make sure it is a lasting success.”

    5
    The magnet gets ready for a test at Brookhaven National Laboratory. Photo: Brookhaven National Laboratory.

    The many moving parts of an accelerator collaboration

    Ensuring lasting success has as much to do with the operational choreography as it does with the exquisite engineering. Conducting logistics that span years and a continent requires painstaking coordination.

    “Planning and scheduling are very important, and they’re quite challenging,” Pong said. “For example, transportation communication: We have to make sure that things are well protected. Otherwise these expensive items can be damaged, so we have to foresee issues and prevent them. Delays also have an impact on the whole project, so we have to ensure components are shipped to destination in a timely schedule.”

    Amm, Apollinari and Pong acknowledge that the three-lab team have met the challenges capably, operating as a well-oiled machine.

    “The technologies developed at Fermilab, Brookhaven and Berkeley helped make the original LHC a success. And now again, these technologies out of the U.S. are really helping CERN be successful,” Amm said. “It’s a dream team, and it’s an honor to be a part of it.”

    The U.S.-based Accelerator Upgrade Project for the HL-LHC, of which the focusing-magnet project is one piece, kicked off in 2016, growing out of a 2003 predecessor R&D program that focused on similar accelerator technology projects.

    From now until about 2025, the U.S. labs will continue to build the large, hulking tubes, starting with fine strands of niobium and tin. They plan to begin delivering in 2022 the first of 16 magnets, plus four spares, to CERN. Installation will take place over the three years following.

    “People say that ‘touchdown’ is a very beautiful word to describe the landing of an airplane, because you have a huge metal object weighing hundreds of tons, descending from the sky, touching a concrete runway very gently,” Pong said. “These magnets are not too different from that. Our magnets are massive superconducting devices, focusing tiny invisible particle beams that are flying close to the speed of light through the bore. It’s quite magical.”

    The magic starts in 2027, when the High-Luminosity LHC comes online.

    “We are doing today the work that future young researchers will use in 10 or 20 years from now to push the frontier of human knowledge, just like it happened when I was a young researcher here at Fermilab, using the Tevatron,” Apollinari said. “It’s a generational passing of the baton. We need to make the machines for the future generations, and with this technology, obviously what we can enable for the future generation is a lot.”

    Learn more about the High-Luminosity LHC in Symmetry and in an 11-minute Fermilab YouTube video.

    Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between the University of Chicago and the Universities Research Association, Inc. Visit Fermilab’s website at http://www.fnal.gov and follow us on Twitter at @Fermilab.

    This accelerator magnet work is supported by the Department of Energy Office of Science.

    See the full here.


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    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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 1:59 pm on March 9, 2020 Permalink | Reply
    Tags: "'Strange' Glimpse into Neutron Stars and Symmetry Violation", , BNL, , STAR detector at the Relativistic Heavy Ion Collider   

    From Brookhaven National Lab: “‘Strange’ Glimpse into Neutron Stars and Symmetry Violation” 

    From Brookhaven National Lab

    March 9, 2020
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    RHIC measurements of ‘hypertriton’ and ‘antihypertriton’ binding energy and mass explore strange-matter interactions and test for ‘CPT’ violation.

    1
    Inner vertex components of the STAR detector at the Relativistic Heavy Ion Collider (righthand view) allow scientists to trace tracks from triplets of decay particles picked up in the detector’s outer regions (left) to their origin in a rare “antihypertriton” particle that decays just outside the collision zone. Measurements of the momentum and known mass of the decay products (a pi+ meson, antiproton, and antideuteron) can then be used to calculate the mass and binding energy of the parent particle. Doing the same for the hypertriton (which decays into different “daughter” particles) allows precision comparisons of these matter and antimatter varieties.

    New results from precision particle detectors at the Relativistic Heavy Ion Collider (RHIC) [below] offer a fresh glimpse of the particle interactions that take place in the cores of neutron stars and give nuclear physicists a new way to search for violations of fundamental symmetries in the universe. The results, just published in Nature Physics, could only be obtained at a powerful ion collider such as RHIC, a U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research at DOE’s Brookhaven National Laboratory.

    The precision measurements reveal that the binding energy holding together the components of the simplest “strange-matter” nucleus, known as a “hypertriton,” is greater than obtained by previous, less-precise experiments. The new value could have important astrophysical implications for understanding the properties of neutron stars, where the presence of particles containing so-called “strange” quarks is predicted to be common.

    The second measurement was a search for a difference between the mass of the hypertriton and its antimatter counterpart, the antihypertriton (the first nucleus containing an antistrange quark, discovered at RHIC in 2010 Science Express). Physicists have never found a mass difference between matter-antimatter partners so seeing one would be a big discovery. It would be evidence of “CPT” violation—a simultaneous violation of three fundamental symmetries in nature pertaining to the reversal of charge, parity (mirror symmetry), and time.

    “Physicists have seen parity violation, and violation of CP together (each earning a Nobel Prize for Brookhaven Lab), but never CPT,” said Brookhaven physicist Zhangbu Xu, co-spokesperson of RHIC’s STAR experiment, where the hypertriton research was done.

    3
    The Heavy Flavor Tracker at the center of the STAR detector.

    But no one has looked for CPT violation in the hypertriton and antihypertriton, he said, “because no one else could yet.”

    The previous CPT test of the heaviest nucleus was performed by the ALICE collaboration at Europe’s Large Hadron Collider (LHC), with a measurement of the mass difference between ordinary helium-3 and antihelium-3. The result, showing no significant difference, was published in Nature Physics in 2015.

    Spoiler alert: The STAR results also reveal no significant mass difference between the matter-antimatter partners explored at RHIC, so there’s still no evidence of CPT violation. But the fact that STAR physicists could even make the measurements is a testament to the remarkable capabilities of their detector.

    Strange matter

    The simplest normal-matter nuclei contain just protons and neutrons, with each of those particles made of ordinary “up” and “down” quarks. In hypertritons, one neutron is replaced by a particle called a lambda, which contains one strange quark along with the ordinary up and down varieties.

    Such strange matter replacements are common in the ultra-dense conditions created in RHIC’s collisions—and are also likely in the cores of neutron stars where a single teaspoon of matter would weigh more than 1 billion tons. That’s because the high density makes it less costly energy-wise to make strange quarks than the ordinary up and down varieties.

    For that reason, RHIC collisions give nuclear physicists a way to peer into the subatomic interactions within distant stellar objects without ever leaving Earth. And because RHIC collisions create hypertritons and antihypertritons in nearly equal amounts, they offer a way to search for CPT violation as well.

    But finding those rare particles among the thousands that stream from each RHIC particle smashup—with collisions happening thousands of times each second—is a daunting task. Add to the challenge the fact that these unstable particles decay almost as soon as they form—within centimeters of the center of the four-meter-wide STAR detector.

    Precision detection

    Fortunately, detector components added to STAR for tracking different kinds of particles made the search a relative cinch. These components, called the “Heavy-Flavor Tracker,” are located very close to the STAR detector’s center. They were developed and built by a team of STAR collaborators led by scientists and engineers at DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab). These inner components allow scientists to match up tracks created by decay products of each hypertriton and antihypertriton with their point of origin just outside the collision zone.

    “What we look for are the ‘daughter’ particles—the decay products that strike detector components at the outer edges of STAR,” said Berkeley Lab physicist Xin Dong. Identifying tracks of pairs or triplets of daughter particles that originate from a single point just outside the primary collision zone allows the scientists to pick these signals out from the sea of other particles streaming from each RHIC collision.

    #IMG3#

    “Then we calculate the momentum of each daughter particle from one decay (based on how much they bend in STAR’s magnetic field), and from that we can reconstruct their masses and the mass of the parent hypertriton or antihypertriton particle before it decayed,” explained Declan Keane of Kent State University (KSU). Telling the hypertriton and antihypertriton apart is easy because they decay into different daughters, he added.

    “Keane’s team, including Irakli Chakeberia, has specialized in tracking these particles through the detectors to ‘connect the dots,’” Xu said. “They also provided much needed visualization of the events.”

    As noted, compiling data from many collisions revealed no mass difference between the matter and antimatter hypernuclei, so there’s no evidence of CPT violation in these results.

    But when STAR physicists looked at their results for the binding energy of the hypertriton, it turned out to be larger than previous measurements from the 1970s had found.

    The STAR physicists derived the binding energy by subtracting their value for the hypertriton mass from the combined known masses of its building-block particles: a deuteron (a bound state of a proton and a neutron) and one lambda.

    “The hypertriton weighs less than the sum of its parts because some of that mass is converted into the energy that is binding the three nucleons together,” said Fudan University STAR collaborator Jinhui Chen, whose PhD student, Peng Liu, analyzed the large datasets to arrive at these results. “This binding energy is really a measure of the strength of these interactions, so our new measurement could have important implications for understanding the ‘equation of state’ of neutron stars,” he added.

    For example, in model calculations, the mass and structure of a neutron star depends on the strength of these interactions. “There’s great interest in understanding how these interactions—a form of the strong force—are different between ordinary nucleons and strange nucleons containing up, down, and strange quarks,” Chen said. “Because these hypernuclei contain a single lambda, this is one of the best ways to make comparisons with theoretical predictions. It reduces the problem to its simplest form.”

    This work was funded by the DOE Office of Science and by funders of the STAR collaboration listed here. The team expressed gratitude to the National Energy Research Scientific Computing Center at Berkeley Lab (another DOE Office of Science user facility) and the Open Science Grid consortium for providing resources and support.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 10:17 am on February 28, 2020 Permalink | Reply
    Tags: "Stunning Images Capture Cosmic Ray Tracks", BNL, , Cosmic rays are made mostly from the result of supernovae explosions and reaching us at nearly the speed of light., Losing more energy as it travels round and round the particle creates the curious circles in the images called “loopers.”, Particles with no electric charge always move in straight lines; however they cannot even be seen by the detector., , , STAR is only able to track charged particles which get pulled by the the detector’s magnetic field creating a curve., The “heart” of the STAR detector is its Time Projection Chamber- a four-meter-wide 4.2-meter-long cylinder filled with a gas mixture of argon and methane.   

    From Brookhaven National Lab: “Stunning Images Capture Cosmic Ray Tracks” 

    From Brookhaven National Lab

    February 26, 2020
    Erika Peters
    epeters@bnl.gov

    The beauty in science shines through at RHIC’s STAR detector [below] and makes a cosmic connection.

    1
    To help calibrate the STAR detector, physicists track and capture images of showers of cosmic rays streaming from space. Can you pick out which image shows tracks from a particle collision at RHIC (hint: the collision occurred at the center of the detector)?

    These images capture the movement and collisions of “cosmic rays”—mysterious particles originating somewhere in deep space—as they stream through the STAR detector at the Relativistic Heavy Ion Collider (RHIC) [below]. The results are profoundly beautiful.

    The rays, made mostly from the result of supernovae explosions and reaching us at nearly the speed of light, are not just things of beauty. Physicists conducting research at RHIC—a U.S. Department of Energy Office of Science user facility for nuclear physics research at Brookhaven National Laboratory—use their signals as a tool for calibrating the massive detectors collecting data for the collider’s physics experiments.

    The “heart” of the STAR detector is its Time Projection Chamber, a four-meter-wide, 4.2-meter-long cylinder filled with a gas mixture of argon and methane, explained Irakli Chakaberia, a research scientist on the STAR experiment. Each of the detector’s endcaps has 12 “sectors,” each with 72 padrows that sense electric charge, acting as a camera that can capture over 2,000 images a second. Tracing the trails of a shower of cosmic rays passing through the gas helps scientists know if their detector components are all working correctly.

    The higher the energy of the original cosmic track, the bigger the proliferation of the shower, creating what appear to be more “lively” images with many tracks in the chamber. How linear the path appears helps show the particle’s speed—the faster the particle moves, the straighter its path. Particles with no electric charge always move in straight lines; however, they cannot even be seen by the detector. STAR is only able to track charged particles, which get pulled by the the detector’s magnetic field, creating a curve. Those with lower momentum, called “soft” particles, are pulled more by the detector’s magnets and curve more than faster ones.

    “Based on the direction of the curve, we can tell whether the particle is positively or negatively charged,” Chakaberia said.

    When a cosmic ray particle collides with an atom of the gas in the detector, it might produce a “softer” particle moving with lower energy. Losing more energy as it travels round and round, the particle creates the curious circles in the images called “loopers.” Sometimes in the initial cascade, there are particles “soft” enough to loop around on their own.

    Even though physicists use powerful computers to analyze data from STAR, “nothing replaces an actual human eye,” Chakaberia said.

    “For example, when looking at some cosmic data, there was a case where tens of tracks were reconstructed in a single detector sector,” Chakaberia said. “This could, in principle, happen, but after checking the event display by eye it was obvious that it was a result of noise in that sector. The software couldn’t distinguish between the noise and real events to some degree. So these track displays help a lot to figure out what’s going on.”

    After cosmic rays have done their job testing and calibrating, STAR is ready to capture the thousands of tracks produced by ion collisions at RHIC. To increase the chance of two ions colliding, billions are aimed at each other with each pass through the detector, and the tracks reveal more of the beauty and the art that can be found in science. In this case, all the particle tracks emerge from the center of the detector, where the collision takes place. (Can you find the one ion-collision event in the images shown here?)

    Nuclear physicists analyze the ion-collision tracks to learn about a remarkable state of matter created in RHIC’s heavy-ion collisions. This “quark-gluon plasma” is a soup of particles that mimics what the universe was like just after the Big Bang. It’s a kind of cosmic connection: Scientists use a detector calibrated by particles from the cosmos to learn more about the marvelous and mystifying universe that created them.

    Research at RHIC/STAR is funded by the DOE Office of Science and by funders of the STAR collaboration listed here.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 10:34 am on February 14, 2020 Permalink | Reply
    Tags: , , BNL, Light Sources Form Data Solution Task Force", ,   

    From Brookhaven National Lab: “Light Sources Form Data Solution Task Force” 

    From Brookhaven National Lab

    February 12, 2020
    Stephanie Kossman
    skossman@bnl.gov

    New collaboration between scientists at the five U.S. Department of Energy light source facilities will develop flexible software to easily process big data.

    BNL NSLS-II

    LBNL ALS

    ANL Advanced Photon Source

    SLAC SSRL Campus

    SLAC LCLS

    Above are the five DOE light sources: Brookhaven National Laboratory’s National Synchrotron Light Source II (NSLS-II), Lawrence Berkeley National Laboratory’s Advanced Light Source (ALS), Argonne National Laboratory’s Advanced Photon Source (APS), and SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS).

    Light source facilities are tackling some of today’s biggest scientific challenges, from designing new quantum materials to revealing protein structures. But as these facilities continue to become more technologically advanced, processing the wealth of data they produce has become a challenge of its own. By 2028, the five U.S. Department of Energy (DOE) Office of Science light sources, will produce data at the exabyte scale, or on the order of billions of gigabytes, each year. Now, scientists have come together to develop synergistic software to solve that challenge.

    With funding from DOE for a two-year pilot program, scientists from the five light sources have formed a Data Solution Task Force that will demonstrate, build, and implement software, cyberinfrastructure, and algorithms that address universal needs between all five facilities. These needs range from real-time data analysis capabilities to data storage and archival resources.

    “It is exciting to see the progress that is being made by all the light sources working together to produce solutions that will be deployed across the whole DOE complex,” said Stuart Campbell, leader of the data acquisition, management and analysis group at the National Synchrotron Light Source II (NSLS-II), a DOE Office of Science user facility at DOE’s Brookhaven National Laboratory.

    In addition, the new software will be designed to facilitate multimodal research—studies that combine data collected from multiple experimental stations, called beamlines. Typically, each beamline at a light source uses custom-built data acquisition software that is incompatible with another beamline’s, making it difficult for scientists to collect and compare data from multiple experimental stations. The task force aims to develop flexible software that can be deployed at multiple beamlines across all five facilities, expanding the possibilities for scientific collaboration.

    2
    Members of the task force met at NSLS-II for a project kickoff meeting in August of 2019.

    To develop the new software, the task force will start by building up existing solutions that can already be found at the five light sources. Two of the key components are Bluesky, an open source software that was created at NSLS-II, and Xi-CAM, which was developed at the Advanced Light Source (ALS) and the Center for Advanced Mathematics for Energy Research Applications—both at DOE’s Lawrence Berkeley National Laboratory. Together, Bluesky and Xi-Cam will provide capabilities like live visualization and interactivity, data processing tools, and the ability to export data in real time into nearly any file format.

    Each of the five light sources in the task force is bringing unique tools and skillsets to help develop a more robust and scalable solution to extract scientific knowledge from data for the nation’s light sources.

    “There is tremendous enthusiasm at the light sources for solving the data challenge,” said Alexander Hexemer, senior scientist and computing program lead at ALS. “We strongly believe this will be the path forward for light sources to work together in the future.”

    With the task force in its early stages, researchers have begun running test experiments on beamlines at NSLS-II and installing Bluesky and Xi-CAM at the Advanced Photon Source, a DOE Office of Science user facility at DOE’s Argonne National Laboratory.

    By the end of the two-year pilot project, “we plan to deliver a set of tools that will provide an end-to-end software solution for the targeted scientific areas that can be deployed and used on different beamlines across all the DOE light sources,” Campbell said.

    Alongside the task force pilot, the five light sources are working with DOE to develop data systems solutions that will scale to the unprecedented data rates that will be produced in the near future, using the new generation of “exascale” computers being built by DOE.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 12:40 pm on February 7, 2020 Permalink | Reply
    Tags: "Making High-Temperature Superconductivity Disappear to Understand Its Origin", (SI-STM)-spectroscopic imaging–scanning tunneling microscopy, , , BNL, , , , , OASIS- a new on-site experimental machine for growing and characterizing oxide thin films., ,   

    From Brookhaven National Lab: “Making High-Temperature Superconductivity Disappear to Understand Its Origin” 

    From Brookhaven National Lab

    February 3, 2020
    Ariana Manglaviti
    amanglaviti@bnl.gov
    (631) 344-2347

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Scientists have collected evidence suggesting that a purely electronic mechanism causes copper-oxygen compounds to conduct electricity without resistance at temperatures well above absolute zero.

    1
    Brookhaven Lab physicists (from left to right) Genda Gu, Tonica Valla, and Ilya Drozdov at OASIS, a new on-site experimental machine for growing and characterizing oxide thin films, such as those of a class of high-temperature superconductors (HTS) known as the cuprates. Compared to conventional superconductors, HTS become able to conduct electricity without resistance at much warmer temperatures. The team used the unique capabilities at OASIS to make superconductivity in a cuprate sample disappear and then reappear in order to understand the origin of the phenomenon.

    When there are several processes going on at once, establishing cause-and-effect relationships is difficult. This scenario holds true for a class of high-temperature superconductors known as the cuprates. Discovered nearly 35 years ago, these copper-oxygen compounds can conduct electricity without resistance under certain conditions. They must be chemically modified (“doped”) with additional atoms that introduce electrons or holes (electron vacancies) into the copper-oxide layers and cooled to temperatures below 100 Kelvin (−280 degrees Fahrenheit)—significantly warmer temperatures than those needed for conventional superconductors. But exactly how electrons overcome their mutual repulsion and pair up to flow freely in these materials remains one of the biggest questions in condensed matter physics. High-temperature superconductivity (HTS) is among many phenomena occurring due to strong interactions between electrons, making it difficult to determine where it comes from.

    That’s why physicists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory studying a well-known cuprate containing layers made of bismuth oxide, strontium oxide, calcium, and copper oxide (BSCCO) decided to focus on the less complicated “overdoped” side, doping the material so much so that superconductivity eventually disappears. As they reported in a paper published on Jan. 29 in Nature Communications, this approach enabled them to identify that purely electronic interactions likely lead to HTS.

    “Superconductivity in cuprates usually coexists with periodic arrangements of electric charge or spin and many other phenomena that can either compete with or aid superconductivity, complicating the picture,” explained first author Tonica Valla, a physicist in the Electron Spectroscopy Group of Brookhaven Lab’s Condensed Matter Physics and Materials Science Division. “But these phenomena weaken or completely vanish with overdoping, leaving nothing but superconductivity. Thus, this is the perfect region to study the origin of superconductivity. Our experiments have uncovered an interaction between electrons in BSCCO that correlates one to one with superconductivity. Superconductivity emerges exactly when this interaction first appears and becomes stronger as the interaction strengthens.”

    Only very recently has it become possible to overdope cuprate samples beyond the point where superconductivity vanishes. Previously, a bulk crystal of the material would be annealed (heated) in high-pressure oxygen gas to increase the concentration of oxygen (the dopant material). The new method—which Valla and other Brookhaven scientists first demonstrated about a year ago at OASIS, a new on-site instrument for sample preparation and characterization—uses ozone instead of oxygen to anneal cleaved samples. Cleaving refers to breaking the crystal in vacuum to create perfectly flat and clean surfaces.

    “The oxidation power of ozone, or its ability to accept electrons, is much stronger than that of molecular oxygen,” explained coauthor Ilya Drozdov, a physicist in the division’s Oxide Molecular Beam Epitaxy (OMBE) Group. “This means we can bring more oxygen into the crystal to create more holes in the copper-oxide planes, where superconductivity occurs. At OASIS, we can overdope surface layers of the material all the way to the nonsuperconducting region and study the resulting electronic excitations.”

    OASIS combines an OMBE system for growing oxide thin films with angle-resolved photoemission spectroscopy (ARPES) and spectroscopic imaging–scanning tunneling microscopy (SI-STM) instruments for studying the electronic structure of these films. Here, materials can be grown and studied using the same connected ultrahigh vacuum system to avoid oxidation and contamination by carbon dioxide, water, and other molecules in the atmosphere. Because ARPES and SI-STM are extremely surface-sensitive techniques, pristine surfaces are critical to obtaining accurate measurements.

    For this study, coauthor Genda Gu, a physicist in the division’s Neutron Scattering Group, grew bulk BSCCO crystals. Drozdov annealed the cleaved crystals in ozone in the OMBE chamber at OASIS to increase the doping until superconductivity was completely lost. The same sample was then annealed in vacuum in order to gradually reduce the doping and increase the transition temperature at which superconductivity emerges. Valla analyzed the electronic structure of BSCCO across this doping-temperature phase diagram through ARPES.

    “ARPES gives you the most direct picture of the electronic structure of any material,” said Valla. “Light excites electrons from a sample, and by measuring their energy and the angle at which they escape, you can recreate the energy and momentum of the electrons while they were still in the crystal.”

    In measuring this energy-versus-momentum relationship, Valla detected a kink (anomaly) in the electronic structure that follows the superconducting transition temperature. The kink becomes more pronounced and shifts to higher energies as this temperature increases and superconductivity gets stronger, but disappears outside of the superconducting state. On the basis of this information, he knew that the interaction creating the electron pairs required for superconductivity could not be electron-phonon coupling, as theorized for conventional superconductors. Under this theory, phonons, or vibrations of atoms in the crystal lattice, serve as an attractive force for otherwise repulsive electrons through the exchange of momentum and energy.

    “Our result allowed us to rule out electron-phonon coupling because atoms in the lattice can vibrate and electrons can interact with those vibrations, regardless of whether the material is superconducting or not,” said Valla. “If phonons were involved, we would expect to see the kink in both the superconducting and normal state, and the kink would not be changing with doping.”

    The team believes that something similar to electron-phonon coupling is going on in this case, but instead of phonons, another excitation gets exchanged between electrons. It appears that electrons are interacting through spin fluctuations, which are related to electrons themselves. Spin fluctuations are changes in electron spin, or the way that electrons point either up or down as tiny magnets.

    Moreover, the scientists found that the energy of the kink is less than that of a characteristic energy at which a sharp peak (resonance) in the spin fluctuation spectrum appears. Their finding suggests that the onset of spin fluctuations (instead of the resonance peak) is responsible for the observed kink and may be the “glue” that binds electrons into the pairs required for HTS.

    Next, the team plans to collect additional evidence showing that spin fluctuations are related to superconductivity by obtaining SI-STM measurements. They will also perform similar experiments on another well-known cuprate, lanthanum strontium copper oxide (LSCO).

    “For the first time, we are seeing something that strongly correlates with superconductivity,” said Valla. “After all these years, we now have a better grasp of what may be causing superconductivity in not only BSCCO but also other cuprates.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 3:26 pm on January 28, 2020 Permalink | Reply
    Tags: "A New Spin on the Basics", BNL, Computer scientists now are at the precipice of a new computing wave: making the leap from supercomputers and bytes to quantum systems and qubits., Ludwig Boltzmann factor calculates the probability that a system of particles can be found in a specific energy state relative to zero energy is widely used in physics., Quantum computers offer another look at classic physics concepts., The collaboration allows Brookhaven (among others in network) access to IBM’s commercial quantum systems including 20- and 53-qubit systems for experiments., The IBM Q Hub at Oak Ridge National Laboratory   

    From Brookhaven National Lab: “A New Spin on the Basics” 

    From Brookhaven National Lab

    January 27, 2020
    Charity Plata
    cplata@bnl.gov

    Quantum computers offer another look at classic physics concepts.

    1
    During the Computational Science Initiative’s Advisory Board Meeting in July 2019, Raffaele Miceli, who co-authored a study of thermo field quantum algorithms while working as a student at CSI, described his quantum computing research to other summer interns at Brookhaven Lab.

    “Think what we can do if we teach a quantum computer to do statistical mechanics,” posed Michael McGuigan, a computational scientist with the Computational Science Initiative at the U.S. Department of Energy’s Brookhaven National Laboratory.

    At the time, McGuigan was reflecting on Ludwig Boltzmann and how the renowned physicist had to vigorously defend his theories of statistical mechanics. Boltzmann, who proffered his ideas about how atomic properties determine physical properties of matter in the late 19th century, had one extraordinarily huge hurdle: atoms were not even proven to exist at the time. Fatigue and discouragement stemming from his peers not accepting his views on atoms and physics forever haunted Boltzmann.

    2
    Probability associated to the wave function of the universe calculated using Qiskit. The vertical axis denotes the probability of realizing a particular configuration in the simple model of early cosmology, while the other axes indicate scale factor of the universe and magnitude of the inflaton field (from Kocher and McGuigan, 2018).

    Today, Boltzmann’s factor, which calculates the probability that a system of particles can be found in a specific energy state relative to zero energy, is widely used in physics. For example, Boltzmann’s factor is used to perform calculations on the world’s largest supercomputers to study the behavior of atoms, molecules, and the quark “soup” discovered using facilities such as the Relativistic Heavy Ion Collider located at Brookhaven Lab and the Large Hadron Collider at CERN.

    BNL/RHIC

    CERN LHC

    SixTRack CERN LHC particles

    While it took a sea change to show Boltzmann was right, computer scientists now are at the precipice of a new computing wave, making the leap from supercomputers and bytes to quantum systems and quantum bits (or “qubits”). These quantum computers have the potential to unlock some of the most mysterious concepts in physics. And, oddly, these so-called mysteries may seem a bit familiar to many.

    Time and Temperature Brought to You by…

    Although most people are well acquainted with the notions of time and temperature and check on them several times a day, it turns out these basic concepts remain enigmatic in physics.

    Boltzmann’s factor helps model temperature effects that can be used to predict and control atomic behavior and physical properties, and they work great on classical computers. However, on a quantum computer, the quantum logic gates used in the computation (akin to logic gates found in digital circuits) are represented by complex numbers, as opposed to Boltzmann’s factor, which by definition, is real.

    ______________________________________

    This is How We Do It: Boltzmann’s Factor for Finite Temperature Calculations

    These calculations typically are done on classical computers using imaginary time formalism and the Monte Carlo method. The imaginary time method treats time as if it is another space coordinate and wraps it up in circle of size proportional to the reciprocal of the temperature. The Monte Carlo method samples the state of the system randomly and chooses the importance of the state based on Boltzmann’s factor.
    ______________________________________

    This issue offered McGuigan and his student/coauthor Raffaele Miceli an interesting problem to tackle using a quantum computing testbed provided by way of Brookhaven Lab’s access agreement to IBM’s universal quantum computing systems, through the IBM Q Hub at Oak Ridge National Laboratory. The collaboration allows Brookhaven (among others in network) access to IBM’s commercial quantum systems, including 20- and 53-qubit systems for experiments.

    “On a quantum computer, there is another way to simulate finite temperature called thermo field dynamics, which is able to compute quantities that are both time- and temperature-dependent,” McGuigan explained. “In this formalism, you construct a double of the system, called the thermo double, then proceed with the calculation on a quantum computer as the computation can be represented in terms of quantum logic gates with complex numbers.

    “In the end, you can sum the double states and generate an effective Boltzmann’s factor for calculations at finite temperature,” he continued. “There also are certain advantages of the formalism. For example, you can study the effects of finite temperature and how the system evolves in real time as time and temperature are separated using this quantum algorithm. One disadvantage is that it requires twice as many qubits as a zero temperature calculation to handle the double states.”

    Miceli and McGuigan demonstrated how to implement the quantum algorithm for thermo field dynamics for finite temperature on a simple system involving a few particles and found perfect agreement with the classical computation.

    ______________________________________

    This is How We Do It: Running a Thermo Field Quantum Algorithm on a Quantum Computer

    In their work, Miceli and McGuigan applied a unitary transformation to discrete quantum mechanical operators to make new Hamiltonians (that measure kinetic energy in particles) with encoded temperature dependence. These were processed into a Pauli matrix representation and input into IBM’s Qiskit [Quantum Information Science kit] software platform. The quantum simulator then calculated an approximation to the Hamiltonian’s ground state energy via the variational quantum eigensolver (VQE), a hybrid algorithm with both quantum and classical components, which is compared to a classically calculated value for the exact energy.
    ______________________________________

    Their work used resources from both classical and quantum computing. According to McGuigan, they used Qiskit open-source quantum computing software that allowed them to create their algorithm in the cloud. Qiskit then transpiled that code to pulses that communicate with a quantum computer in real time (in this case, an IBM Q device). Optimizers that run classical algorithms further enable the back and forth between the traditional and quantum systems.

    “Our experiment shows quantum systems have an advantage of representing real-time calculations exactly rather than rotating from imaginary time to real time to find a result,” McGuigan explained. “It offers a truer picture of how a system evolves. We can map the problem to a quantum simulation that lets it evolve.”

    Into the Cosmos

    Quantum cosmology is another area where McGuigan anticipates that new quantum computing options will have profound impact. Despite the multitude of advances in understanding the universe made possible by modern supercomputers, some physical systems remain beyond their reach. The mathematical complexity, which usually includes accounting for full quantum gravity theory, is simply too great to obtain exact solutions. However, a true quantum computer, complete with the ability to exploit entanglement and superposition, would expand the options for new, more precise algorithms.

    “Quantum systems can realize path integrals in real time, giving us access to large-scale simulations of the universe,” McGuigan said. “You can visualize the calculated wavefunction of the universe as it evolves forward without first formulating a full theory of quantum gravity.”

    Again, using the Qiskit package and access to IBM Q hardware, McGuigan and his collaborator Charles Kocher, a student at Brown University, employed a mix of classical computational methods and VQE to run varied experiments, including one that examined systems with gravity coupled to a boson field called an inflaton, a hypothetical particle that plays an important role in modern cosmology. Their work showed the hybrid VQE yielded wavefunctions consistent with the Wheeler-Dewitt equation, which mathematically combines quantum mechanics with Albert Einstein’s theory of relativity.

    Inspiration on an Expanding Scale

    While early quantum experiments are leading to different perspectives of the basics behind physics, quantum computing is expected to contribute major advances toward solving longstanding problems impacting DOE’s missions. Among them, it can be a tool for unveiling new materials, solving energy challenges, or adding to fundamental understandings (like time and temperature) in high energy physics and cosmology. In turn, these changes could cascade into more readily recognizable areas.

    For example, drug developers need more realized quantum mechanics to understand the structure of molecules. Quantum computers can enable discoveries by affording simulations of the full quantum mechanics that would provide a truly practical point of view.

    “There seems to always be interest in the basics behind physics,” McGuigan said. “It has been of interest to the public for millennia. Right now, the combination of theoretical expertise and actual technology is converging with quantum computing. Yet, it still is a very human endeavor.”

    For now, using near-term quantum computers to solve small thermo field problems or to take a new look at an old universe is inspiring researchers to scale up their algorithms as they do bigger things in science.

    “We get emboldened to do different things. We all do,” McGuigan said. “Other groups around the world, such as the Perimeter Institute in Canada and Universiteit van Amsterdam in the Netherlands, are already extending the thermo field double quantum algorithm to even bigger systems. With the emergence of large near-term quantum computers of 50-100 qubits, the goal is to run finite temperature simulations on realistic systems involving many particles. It is exciting to have an actual quantum computer to test these ideas and problems that we once had no solutions for. Quantum mechanics with no tradeoffs—that is what science is all about.”

    This research was supported by DOE’s Office of Science and the Supplemental Undergraduate Research Program (SURP) at Brookhaven Lab.

    Related:
    Miceli R and M McGuigan (2019).“Thermo field dynamics on a quantum computer.”
    IEEE Xplore Digital Library

    Kocher C and M McGuigan (2018). “Simulating 0+1 Dimensional Quantum Gravity on Quantum Computers: Mini-Superspace Quantum Cosmology and the World Line Approach in Quantum Field Theory.”
    IEEE Xplore Digital Library

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 9:54 am on December 6, 2019 Permalink | Reply
    Tags: , BNL, , , NSLS,   

    From D.O.E. Office of Science via Brookhaven National Lab: “The Big Questions: José Rodriguez on Catalysts” 

    Brookhaven National Lab

    December 4, 2019
    José Rodriguez

    1
    Distinguished Scientists Fellow José Rodriguez from Brookhaven Lab worked with fellow chemist Ping Liu to characterize structural and mechanistic details of a low-temperature catalyst for producing hydrogen gas from water and carbon monoxide.
    Image courtesy of Brookhaven National Laboratory.

    The Big Questions series features perspectives from the five recipients of the Department of Energy Office of Science’s 2019 Distinguished Scientists Fellows Award describing their research and what they plan to do with the award.

    Contributing Author Credit: José Rodriguez is a senior chemist at Brookhaven National Laboratory.

    How can we use some of the world’s brightest and strongest sources of synchrotron light to better understand the catalysts that speed up chemical reactions?

    Catalysts reduce the energy needed to make a chemical reaction take place. They’re essential in industry, used for making everything from fabric to synthetic plants. Catalysts are used in the production of many chemicals and fuels.

    Over the years, people have tried to understand how catalysts work in hopes of making them even better. To understand how a catalyst works, you need to see what happens at its active sites during chemical transformations. This is a very complex thing. You need a lot of tools to see how the catalyst changes over time, especially under harsh environmental conditions like high pressures and temperatures. Synchrotrons – incredibly powerful sources of light that produce X-rays – can provide a unique look into how these catalysts work.

    When I first arrived at the Department of Energy’s Brookhaven National Laboratory (BNL) 29 years ago, scientists were for the first time seriously proposing the use of a synchrotron to study catalysts. At that time, there was a lot of activity in the National Synchrotron Light Source (NSLS), a DOE Office of Science user facility.

    BNL NSLS

    At the end of my job interview, the head of BNL’s Chemistry Department asked, “How much money do you need to do this kind of science?” I said, “This is a very complex science. I need $750,000.” As a physical inorganic chemist, $50,000 was a lot of research money for him. But despite the price tag, he looked at me and said, “Okay, we’ll see what we can do.” He called up the person at DOE in charge of the catalysis program and said, “The young man looks very promising; we want to go into this new area. He needs $750,000.”

    With that funding, my team and I used NSLS to study catalysts in very controlled environments. We created these environments by putting the catalysts in specialized ultra-high vacuum chambers originally developed by NASA in the 1960s. After setting the inside of the chambers to the conditions we wanted, we put them in the synchrotron. The hard and soft X-rays from the synchrotron made it possible to study the structural, electronic, and chemical properties of the catalytic material as well as how those changed during the reaction process.

    There is still a big interest in the DOE Office of Science in understanding these catalytic materials. Since then, the NSLS has been replaced by its successor NSLS-II [below], which is also a DOE Office of Science user facility. With NSLS-II, we can use a high-intensity beam to do ultra-fast measurements. Now, we can make in-situ measurements of samples with highly diluted elements in times as short as milliseconds (a thousandth of a second). With this speed, we can now monitor catalysts’ properties during reactions very quickly. In catalysis research, the faster you can go, the better.

    With this fellowship, I’m going to expand the work we’re doing at the NSLS-II to better understand catalysts’ properties and how they change during reactions. While we’ve been working on this project for about five years, this new funding will help us move it forward. This work will involve not just the NSLS-II, but also researchers at BNL’s Center for Functional Nanomaterials (a DOE Office of Science user facility), the University of Kansas, Stony Brook University, and Columbia University. In the spirit of this fellowship, any equipment we develop will remain at the NSLS-II, where it will be available for the entire catalysis community to use.

    I think this project has the potential to make a big contribution to the field and I appreciate the opportunity the DOE’s Office of Science has provided me to lead it.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus


    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
    i1

     
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