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  • richardmitnick 9:55 am on March 28, 2019 Permalink | Reply
    Tags: "The bulk of our data come from looking at energies and times of decay positrons that came from the muons” said Brendan Kiburg a Fermilab particle physicist, At rest muons decay in just two millionths of a second. That decay produces two neutrinos and a positron which is a positively charged electron., , FNAL Muon g-2,   

    From Fermi National Accelerator Lab: “Muon g-2 begins second run” 

    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.

    1
    The Muon g-2 experiment recently started its second run. Scientists use this particle storage, a 50-foot-diameter magnet, to look for hidden particles and forces. Photo: Reidar Hahn

    Earlier this month, the Muon g-2 (“g minus two”) experiment at Fermilab began its second run to search for hidden particles and forces.

    Over the next three months, scientists expect to accumulate double the amount of data collected in Run 1 and make the world’s most precise measurement of the muon’s anomalous magnetic moment, often expressed as the quantity g-2.

    Run 2 features several improvements that scientists made to the experiment over the past eight months.

    “We’re looking to have a more stable environment in which we take the data, because in the first data-taking period we were trying to get things working and evaluating how they’re working,” said Mark Lancaster, the experiment’s co-spokesperson and a professor of physics at the University of Manchester and University College London. “Now we’re trying to move into the mode where things are much more stable, and we can run for a reasonable period of time without any interventions.”

    Muons are elementary particles similar to, but much heavier than, electrons. A muon’s magnetic moment — a characteristic related to the orientation and strength of its internal magnet — changes as it spins, an effect called precession. Lancaster and his colleagues are measuring the precession frequency of the magnetic moment very precisely and comparing the result to what theorists predict it should be. In doing so, they hope to confirm, or even revise, the Standard Model of particle physics.

    Standard Model of Particle Physics (LATHAM BOYLE AND MARDUS OF WIKIMEDIA COMMONS)

    “As it travels through the universe, a particle is never really strictly alone,” said Fermilab’s Chris Polly, the experiment’s other co-spokesperson. “There’s constantly an entourage of other particles that appear out of the vacuum. They come out of nowhere, and they disappear just as quickly as they popped into existence.”

    Those particles slightly change the muon’s magnetic moment. By calculating how often they will pop in and out of the vacuum and interact with the muon, scientists can predict the impact of all the known particles on the magnetic moment to very high precision. The comparison of this prediction with the experimentally obtained value will tell scientists whether there are additional, undiscovered particles or forces that change the magnetic moment.

    At rest, muons decay in just two millionths of a second. That decay produces two neutrinos and a positron, which is a positively charged electron.

    “The bulk of our data come from looking at energies and times of decay positrons that came from the muons,” said Brendan Kiburg, a Fermilab particle physicist involved in the experiment.

    Getting that data requires a very uniform, precisely measured magnetic field.

    “It’s incredibly important that we know the magnetic field the muons are experiencing,” Kiburg said. “Since the new physics that we’re looking for is embedded in the precession frequency, you have to make sure that the muons don’t see a different magnetic field than the one we’re measuring.”

    Fine-tuning the ring

    The experiment’s storage ring magnet came to Fermilab from its original home at Brookhaven National Laboratory in 2013. After years of construction and adjustments, operators got the beam tuned up and engaged in Run 1, a three-month production run in 2018.

    “Because of that production run, we were able to learn about a few deficiencies that we really needed to fix,” Polly said.

    There are several areas the team focused on over the summer. The first was a system of quadrupole magnets that focus the muons and prevent them from spiraling up or down.

    “We discovered during the shutdown that we needed to improve the reliability of the quadrupoles’ operation, especially at the higher voltages that we would like to achieve in the upcoming run,” Polly said.

    Another issue involved a device called an electromagnetic kicker. It shifts the muons’ orbit very slightly to keep them on a path that stays inside the ring.

    “The kicker is probably the single most important component of the experiment beyond the ring itself,” Kiburg said.

    Without the kicker, the muons behave like a Formula One driver whose racecar is at the wrong angle, sending them careening into the wall on the first lap. To avoid this, the kicker shifts the angle of the muons as they come through the ring’s gate.

    “One of the issues with the kicker at Brookhaven was that it was too slow,” Polly said. “Instead of giving the muons a kick on the first turn and shutting off, the kicker pulse continued for two or three revolutions around the ring. That was less than ideal, so we designed a kicker for this experiment that could be up and back down in a single turn.”

    While the kick deployed during Run 1 at Fermilab was three times faster, it wasn’t strong enough to push the muons into precisely the perfect orbit around the ring. During the shutdown, the team upgraded the ring to accommodate a more powerful kicker.

    The third problem was the temperature control in the Muon g-2 building. The magnetic storage-ring is extremely sensitive to temperature — so much so that a change of more than a single degree Celsius can cause it to expand or contract, degrading the magnetic field. While performing Run 1 during the hottest summer months, maintaining the facility’s temperature was a challenge. Improvements to the facility’s heating and cooling systems should fix that, Polly said.

    A mountain of data

    The team recently began bringing beam to the storage ring and testing that the upgrades worked as planned. A key goal of Run 2 is to measure the magnetic moment very precisely, to 70 parts per billion. To get that kind of precision, the magnetic field must be highly uniform.

    “We were able to adjust the magnetic field so that it’s two to three times more uniform,” Polly said. “So, though we’re using the same container, we’ve in fact turned it into a much better container in terms of understanding this magnetic field.”

    The team also had to boost the experiment’s muon flux, the number of muons per second required to reach the necessary statistical precision. In Run 1, they achieved about half of their goal. A bevy of upgrades completed over the summer is expected to increase the flux to about 75 percent of the goal. A final upgrade the team is considering for next summer would get the flux the rest of the way, Polly said.

    One upcoming challenge is the sheer volume of data. Run 2 aims to reduce the uncertainty in the result from the Brookhaven Muon g-2 experiment by a factor of four, which requires 16 times the statistics. That’s a lot of data.

    “Our aim is to process the data as it arrives,” Lancaster said. “We’re using distributed computing for everything, so we process everything on the grid. Part of what we’re striving to do is to make that more robust and reliable.”

    And robustness and reliability require rigor.

    “This is why you go through the whole design process so carefully,” Kiburg said. “It’s so you can get to a point where you are turning it into a physics result, and we are on the doorstep there, so this is a fun time.”

    The Muon g-2 experiment is supported by DOE’s Office of Science.

    See the full article here.


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    FNAL Icon

    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.

    FNAL MINERvA front face Photo Reidar Hahn

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL MINOS Far Detector in the Soudan Mine in northern Minnesota

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 12:41 pm on October 23, 2018 Permalink | Reply
    Tags: , , , FNAL Muon g-2, High-Luminosity LHC (HL-LHC) at CERN, , LBNL/DESI Dark Energy Spectroscopic Instrument for the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson Ariz USA, SLAC Large Synoptic Survey Telescope at Cerro Pachon Chile, ,   

    From Symmetry: “The building boom” 

    Symmetry Mag
    From Symmetry

    10/23/18
    By Diana Kwon

    4
    Illustration by Sandbox Studio, Chicago with Ana Kova

    These international projects, selected during the process to plan the future of US particle physics, are all set to come online within the next 10 years.

    A mile below the surface at Sanford Underground Research Facility in South Dakota, crews are preparing to excavate more than 800,000 tons of rock. Once the massive caverns they’re creating are complete, they will install four modules that make up a giant particle detector for the Deep Underground Neutrino Experiment. DUNE, hosted by the US Department of Energy’s Fermi National Accelerator Laboratory, is an ambitious, international effort to study neutrinos—the tiny, elusive and yet most abundant matter particles in the universe.

    DUNE is one of several particle physics and astrophysics projects with US participation currently under some stage of construction. These include large-scale projects, such as the construction of Mu2e, the muon-to-electron conversion experiment at Fermilab, and upgrades to the Large Hadron Collider at CERN. And they include smaller ones, such as the assembly of the LZ and SuperCDMS dark matter experiments. Together, these scientific endeavors will investigate a wide range of important concepts, including neutrino mass, the nature of dark matter and cosmic acceleration.

    “In the last 10 years, there have been many facilities in the US that wound down,” says Saul Gonzalez, a program director at the National Science Foundation. “But right now we’re definitely going through a boom—it’s a very exciting time.”

    A community effort

    Members of the US particle physics community identified these projects through a regularly occurring study of the field called the Snowmass planning process, named after the Colorado village where some of the first such dialogs took place in the early 1980s.

    After the most recent Snowmass meeting in Minneapolis in 2013, the 25-member Particle Physics Project Prioritization Panel, or P5, gathered to pinpoint the most important scientific problems in particle physics and propose a 10-year plan to take them on. “Snowmass enabled us to get the questions out there as a field,” says Steven Ritz, the University of California, Santa Cruz physicist who led the P5 panel. “But we’re also aware that budgets are constrained—so P5’s job was to prioritize them.”

    P5’s report, which was published in May 2014 [PDF], outlined five key areas of study: the Higgs boson; neutrinos; dark matter; dark energy and cosmic inflation; and undiscovered particles, interactions and physical principles.

    Shorter-term efforts to address questions in these areas, such as the Mu2e experiment and the Large Synoptic Survey Telescope in Chile, both already under construction, have projected start-up dates around 2020. Longer-term plans, such as DUNE and the high-luminosity upgrade to the LHC, are expected be ready for physics in the mid to latter part of the 2020s.

    “If you look at the timeline, we don’t build everything at once, because of budget and resource constraints,” says Young-Kee Kim, a physicist at the University of Chicago and a former member of the High Energy Physics Advisory Panel, the advisory group that P5 reports to.

    Another consideration was the importance of maintaining a continual stream of data, Ritz says. “We didn’t want to have a building boom where there was no new data for 5 or 10 years.”

    Having multiple experiments at various stages of completion is important for junior scientists. “If you’re a grad student or a postdoc and you’re working on something that’s not going to have physics data until 2024, that’s kind of a problem,” says Kate Scholberg, a physicist at Duke University who was on the P5 panel.

    A staggered timeline gives junior scientists the option of working on a project like DUNE, where they can contribute to research and development, then switch to another experiment where data is available for analysis.

    “Being in a construction phase does have some short-term challenges, but it’s really important as an investment for the future,” Scholberg says. “Because if you stop constructing, then eventually you’re not going to have any more data.”

    Global contributions

    The United States is not undertaking these experiments alone. “Every experiment is really an international collaboration,” Gonzalez says.

    The DUNE collaboration, for example, already includes more than 1100 scientists from 32 countries and counting. And although the Long-Baseline Neutrino Facility, the future home of DUNE, will be in the US, researchers are currently building prototype detectors for the project at the CERN research center in Europe.

    More than 1700 US scientists participate in research at the LHC at CERN; many of them are currently working on future upgrades to the accelerator and its experiments. Although LSST will operate on a mountaintop in Chile, its gigantic digital camera is being assembled at SLAC National Accelerator Laboratory using parts from institutions elsewhere in the United States and in France, Germany and the UK.

    Smaller experiments also have a global presence. Dark matter experiment SuperCDMS, a 23-institution collaboration led by SLAC, will be located at SNOLAB underground laboratory in Ontario and has members in Canada, France and India.

    People with specialized expertise are needed to build the apparatus for these experiments. For example, Fermilab’s Proton Improvement Plan-II, a project to upgrade the lab’s particle accelerator complex to provide protons beams for DUNE, requires individuals with expertise in superconducting radio-frequency technology. “We’re tapping into the SRF expertise around the world to build this,” says Michael Procario, the Director of the Facilities Division in the Office of High Energy Physics within DOE’s Office of Science.

    These DOE-supported endeavors—and the theory and data analysis that go along with them—will likely keep scientists busy until 2035 and beyond. “All the experiments are going to give us definitive answers. Even a null result will give us important information,” Ritz says. “I think it’s a great time for physics.”

    The experiments:

    Muon g-2

    FNAL Muon g-2 studio

    This experiment will measure the magnetic moment of a muon, a subatomic particle 200 times more massive than an electron, in an attempt to identify physics beyond the Standard Model.

    Location: Fermilab, Illinois, United States
    Lead institution: Fermilab
    Currently running

    Axion Dark Matter Experiment (ADMX-Gen 2)

    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington

    U Washington ADMX

    Physicists are probing for signs of axions, hypothetical low-mass dark matter particles at the University of Washington-based ADMX detector.

    Location: University of Washington, United States
    Lead institution: University of Washington
    Currently running

    Physicists will use Mu2e to search for the never-observed direct conversion of a muon into an electron, a process predicted by theories beyond the Standard Model.

    FNAL Mu2e facility under construction


    FNAL Mu2e solenoid

    Location: Fermilab, Illinois, United States
    Lead institution: Fermilab
    Scheduled start-up: 2020

    LUX-ZEPLIN (LZ)

    LBNL LZ project at SURF, Lead, SD, USA


    LZ Dark Matter Experiment at SURF lab

    A liquified xenon detector surrounded by 70,000 gallons of water will be located more than 4000 feet underground at the Sanford Underground Research Facility, where researchers will hunt for interactions between matter and dark matter.

    Location: Sanford Lab, South Dakota, United States
    Lead institution: Berkeley Lab
    Scheduled start-up: 2020

    Dark Energy Spectroscopic Instrument (DESI)

    LBNL/DESI Dark Energy Spectroscopic Instrument for the Nicholas U. Mayall 4-meter telescope at Kitt Peak National Observatory near Tucson, Ariz, USA


    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Scientists will measure the effect of dark energy on cosmic expansion at the 4-meter Mayall Telescope at Kitt Peak National Observatory in Arizona.

    Location: Kitt Peak National Observatory, Arizona, United States
    Lead institution: Berkeley Lab
    Scheduled start-up: 2021

    Super Cyogenic Dark Matter Search (SuperCDMS)

    SNOLAB, a Canadian underground physics laboratory at a depth of 2 km in Vale’s Creighton nickel mine in Sudbury, Ontario

    SNOLAB, a Canadian underground physics laboratory at a depth of 2 km in Vale’s Creighton nickel mine in Sudbury, Ontario

    SLAC SuperCDMS, at SNOLAB (Vale Inco Mine, Sudbury, Canada)

    SLAC SuperCDMS, at SNOLAB (Vale Inco Mine, Sudbury, Canada)

    Physicists will hunt for dark matter particles with a cryogenic germanium detector located deep underground at SNOLAB in Canada.

    Location: SNOLAB, Ontario, Canada
    Lead institution: SLAC
    Scheduled start-up: Early 2020s

    Large Synoptic Survey Telescope (LSST)

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    The 8-meter Large Synoptic Survey Telescope, situated in northern Chile, will observe the whole accessible sky hundreds of times over 10 years to produce the deepest, widest image of the universe to date. This will allow physicists to probe questions about dark energy, dark matter, galaxy formation and more.

    Location: Cerro Pachon, Chile
    Lead institution: SLAC
    Scheduled start-up: Early 2020s

    Proton Improvement Pla-II (PIP-II)

    Upgrades to the Fermilab accelerator complex, including the construction of a 175-meter-long superconducting linear particle accelerator, will create the high-intensity proton beam that will produce beams of neutrinos for DUNE.

    Location: Fermilab, Illinois, United States
    Lead institution: Fermilab
    Scheduled start-up: mid-2020s

    Deep Underground Neutrino Experiment (DUNE)

    CERN Proto DUNE Maximillian Brice

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    SURF DUNE LBNF Caverns at Sanford Lab

    Scientists will send the world’s most powerful beam of neutrinos through two sets of detectors separated by 800 miles—one at the source of the beam at Fermilab in Illinois and the other at Sanford Underground Research Facility in South Dakota—to help scientists address fundamental concepts in particle physics, such as neutrino mass, matter-antimatter asymmetry, proton decay and black hole formation.

    Location: Fermilab, Illinois and Sanford Lab, South Dakota, United States
    Lead institution: Fermilab
    Scheduled partial start-up (with two detector modules): 2026

    High-Luminosity LHC (HL-LHC)

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    An upgrade to CERN’s Large Hadron Collider will increase its luminosity—the number of collisions it can achieve—by a factor of 10. More collisions means more data and a higher probability of spotting rare events. The LHC experiments will receive upgrades to manage the higher collision frequency.

    Location: CERN, near Geneva, Switzerland
    Lead institution: CERN
    Scheduled start-up: 2026

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:53 am on July 17, 2018 Permalink | Reply
    Tags: , , Beams off and hardhats on, Fermilab Linac will undergo upgrades to improve its reliability during the accelerator shutdown, , FNAL Muon g-2, ,   

    From Fermilab: “Beams off, hardhats on” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    July 12, 2018
    Lauren Biron

    1
    The Fermilab Linac will undergo upgrades to improve its reliability during the accelerator shutdown. Photo: Reidar Hahn

    Summer means hot days, pool parties and Fermilab’s annual accelerator shutdown, when crews of technicians enter the tunnels to upgrade and maintain the complex machines.

    For many months Fermilab’s accelerator complex has been delivering quality beam to experiments, with record up times and delivery of protons. This means more data for Fermilab’s hungry physics experiments. The proton beam delivered by the accelerator complex first reached a milestone of 700 kilowatts in 2016 and has been regularly running at this impressive power since around Christmas.

    “It’s been a very good year for beam delivery,” said Fermilab’s Duane Newhart, deputy head of accelerator operations. “We’ve broken just about every record every machine has set this past year.”

    The last two shutdowns were focused on upgrades to improve the accelerator complex, part of the Proton Improvement Plan.

    “This shutdown is more maintenance-driven,” said Fermilab physicist Cons Gattuso, who coordinates the installation and maintenance activities during the shutdown. “While we have some of the best particle accelerators in the world, some of the equipment we operate is 40 years old. And we ask it to do more and more.”

    The accelerator performance should see some gains when the machines come back online around mid-September. And there are still major projects in the works.

    Technicians will finish the second half of an upgrade to the linear accelerator, or Linac. The required components, called Marx modulators, provide high voltage for the amplifiers and were designed and built at Fermilab. As modern replacements for old vacuum tubes that are hard to repair or replace, the new pieces of tech will improve the Linac’s reliability. One particular kind of vacuum tube is known as the 1123.

    “There are about 90 left in the world, and Fermilab owns all of them,” Newhart said.

    Other work includes changing out a component known as a target, which helps produce particles for study — in this case, neutrinos. Accelerator teams will also add components to improve beamline diagnostics, modify vacuum systems, and replace and repair magnets. One particular magnet in the Main Injector accelerator will need some attention.

    “We haven’t had to change out a Lambertson magnet in the Main Injector accelerator since things were installed, some 25 years ago,” said Gattuso, referring to the lab’s flagship accelerator. “This is a testament to the quality and resilience of the components.”

    2
    The Muon g-2 experiment takes advantage of the lab’s powerful accelerator complex. Fermilab scientists have already collected twice the amount of total data gathered over its four years at Brookhaven National Laboratory, where the experiment ran prior to coming to Fermilab. Photo: Reidar Hahn

    This will be the first shutdown since Fermilab’s Muon Campus came online last year. Technicians will work on the vacuum system for the upcoming muon-to-electron conversion experiment, known as Mu2e, completing about half the beamline that connects the experiment to the Muon Campus Delivery Ring by the end of the shutdown. They’ll also add devices that help reduce the spread of the particle beam for the Muon g-2 experiment.

    Muon g-2 reuses a giant, 50-foot-diameter particle storage ring from a similar experiment that studied properties of muons at Brookhaven National Laboratory from 1997 to 2001. The ring was transported to Fermilab in 2013 to take advantage of the lab’s powerful accelerator complex and officially started up in 2018. Scientists have already collected twice the amount of total data gathered over four years at Brookhaven.

    “We have a plan in place to double the muon flux this summer with a number of upgrades,” said Fermilab scientist and Muon g-2 co-spokesperson Chris Polly. “Hopefully we emerge from the shutdown taking the equivalent of one full Brookhaven data set every month.”

    See the full article here .


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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 2:17 pm on July 14, 2018 Permalink | Reply
    Tags: , , , FNAL Muon g-2, ,   

    From Brookhaven via Fermilab : “Theorists Publish Highest-Precision Prediction of Muon Magnetic Anomaly 

    From Brookhaven Lab

    via

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    7.12.18
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    Latest calculation based on how subatomic muons interact with all known particles comes out just in time for comparison with precision measurements at new “Muon g-2” experiment.

    FNAL Muon G-2 studio at FNAL

    Theoretical physicists at the U.S. Department of Energy’s (DOE’s) Brookhaven National Laboratory and their collaborators have just released the most precise prediction of how subatomic particles called muons—heavy cousins of electrons—“wobble” off their path in a powerful magnetic field. The calculations take into account how muons interact with all other known particles through three of nature’s four fundamental forces (the strong nuclear force, the weak nuclear force, and electromagnetism) while reducing the greatest source of uncertainty in the prediction. The results, published in Physical Review Letters as an Editors’ Suggestion, come just in time for the start of a new experiment measuring the wobble now underway at DOE’s Fermi National Accelerator Laboratory (Fermilab).

    A version of this experiment, known as “Muon g-2,” ran at Brookhaven Lab in the late 1990s and early 2000s, producing a series of results indicating a discrepancy between the measurement and the prediction. Though not quite significant enough to declare a discovery, those results hinted that new, yet-to-be discovered particles might be affecting the muons’ behavior. The new experiment at Fermilab, combined with the higher-precision calculations, will provide a more stringent test of the Standard Model, the reigning theory of particle physics. If the discrepancy between experiment and theory still stands, it could point to the existence of new particles.

    “If there’s another particle that pops into existence and interacts with the muon before it interacts with the magnetic field, that could explain the difference between the experimental measurement and our theoretical prediction,” said Christoph Lehner, one of the Brookhaven Lab theorists who led the latest calculations. “That could be a particle we’ve never seen before, one not included in the Standard Model.”

    Finding new particles beyond those already cataloged by the Standard Model has long been a quest for particle physicists. Spotting signs of a new particle affecting the behavior of muons could guide the design of experiments to search for direct evidence of such particles, said Taku Izubuchi, another leader of Brookhaven’s theoretical physics team.

    “It would be a strong hint and would give us some information about what this unknown particle might be—something about what the new physics is, how this particle affects the muon, and what to look for,” Izubuchi said.

    The muon anomaly

    The Muon g-2 experiment measures what happens as muons circulate through a 50-foot-diameter electromagnet storage ring. The muons, which have intrinsic magnetism and spin (sort of like spinning toy tops), start off with their spins aligned with their direction of motion. But as the particles go ’round and ’round the magnet racetrack, they interact with the storage ring’s magnetic field and also with a zoo of virtual particles that pop in and out of existence within the vacuum. This all happens in accordance with the rules of the Standard Model, which describes all the known particles and their interactions, so the mathematical calculations based on that theory can precisely predict how the muons’ alignment should precess, or “wobble” away from their spin-aligned path. Sensors surrounding the magnet measure the precession with extreme precision so the physicists can test whether the theory-generated prediction is correct.

    Both the experiments measuring this quantity and the theoretical predictions have become more and more precise, tracing a journey across the country with input from many famous physicists.

    A race and collaboration for precision

    “There is a race of sorts between experiment and theory,” Lehner said. “Getting a more precise experimental measurement allows you to test more and more details of the theory. And then you also need to control the theory calculation at higher and higher levels to match the precision of the experiment.”

    With lingering hints of a new discovery from the Brookhaven experiment—but also the possibility that the discrepancy would disappear with higher precision measurements—physicists pushed for the opportunity to continue the search using a higher-intensity muon beam at Fermilab. In the summer of 2013, the two labs teamed up to transport Brookhaven’s storage ring via an epic land-and-sea journey from Long Island to Illinois. After tuning up the magnet and making a slew of other adjustments, the team at Fermilab recently started taking new data.

    Meanwhile, the theorists have been refining their calculations to match the precision of the new experiment.

    “There have been many heroic physicists who have spent a huge part of their lives on this problem,” Izubuchi said. “What we are measuring is a tiny deviation from the expected behavior of these particles—like measuring a half a millimeter deviation in the flight distance between New York and Los Angeles! But everything about the fate of the laws of physics depends on that difference. So, it sounds small, but it’s really important. You have to understand everything to explain this deviation,” he said.

    The path to reduced uncertainty

    By “everything” he means how all the known particles of the Standard Model affect muons via nature’s four fundamental forces—gravity, electromagnetism, the strong nuclear force, and the electroweak force. Fortunately, the electroweak contributions are well understood, and gravity is thought to play a currently negligible role in the muon’s wobble. So the latest effort—led by the Brookhaven team with contributions from the RBC Collaboration (made up of physicists from the RIKEN BNL Research Center, Brookhaven Lab, and Columbia University) and the UKQCD collaboration—focuses specifically on the combined effects of the strong force (described by a theory called quantum chromodynamics, or QCD) and electromagnetism.

    “This has been the least understood part of the theory, and therefore the greatest source of uncertainty in the overall prediction. Our paper is the most successful attempt to reduce those uncertainties, the last piece at the so-called ‘precision frontier’—the one that improves the overall theory calculation,” Lehner said.

    The mathematical calculations are extremely complex—from laying out all the possible particle interactions and understanding their individual contributions to calculating their combined effects. To tackle the challenge, the physicists used a method known as Lattice QCD, originally developed at Brookhaven Lab, and powerful supercomputers. The largest was the Leadership Computing Facility at Argonne National Laboratory, a DOE Office of Science user facility, while smaller supercomputers hosted by Brookhaven’s Computational Sciences Initiative (CSI)—including one machine purchased with funds from RIKEN, CSI, and Lehner’s DOE Early Career Research Award funding—were also essential to the final result.

    “One of the reasons for our increased precision was our new methodology, which combined the most precise data from supercomputer simulations with related experimental measurements,” Lehner noted.

    Other groups have also been working on this problem, he said, and the entire community of about 100 theoretical physicists will be discussing all of the results in a series of workshops over the next several months to come to agreement on the value they will use to compare with the Fermilab measurements.

    “We’re really looking forward to Fermilab’s results,” Izubuchi said, echoing the anticipation of all the physicists who have come before him in this quest to understand the secrets of the universe.

    The theoretical work at Brookhaven was funded by the DOE Office of Science, RIKEN, and Lehner’s Early Career Research Award.

    The Muon g-2 experiment at Fermilab is supported by DOE’s Office of Science and the National Science Foundation. The Muon g-2 collaboration has almost 200 scientists and engineers from 34 institutions in seven countries. Learn more about the new Muon g-2 experiment or take a virtual tour.

    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.
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  • richardmitnick 10:55 am on July 11, 2018 Permalink | Reply
    Tags: , E821 storage-ring experiment at Brookhaven National Laboratory, FNAL Muon g-2, , , ,   

    From CERN Courier: “Muons accelerated in Japan” 


    From CERN Courier

    9 July 2018

    1
    Installation. No image credit.

    Muons have been accelerated by a radio-frequency accelerator for the first time, in an experiment performed at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai, Japan. The work paves the way for a compact muon linac that would enable precision measurements of the muon anomalous magnetic moment and the electric dipole moment.

    Japan Proton Accelerator Research Complex J-PARC, located in Tokai village, Ibaraki prefecture, on the east coast of Japan


    Japan Proton Accelerator Research Complex J-PARC, located in Tokai village, Ibaraki prefecture, on the east coast of Japan

    Around 15 years ago, the E821 storage-ring experiment at Brookhaven National Laboratory (BNL) reported the most precise measurement of the muon anomalous magnetic moment (g-2).

    1
    E821 storage-ring experiment at Brookhaven National Laboratory (BNL)

    Achieving an impressive precision of 0.54 parts per million (ppm), the measured value differs from the Standard Model prediction by more than three standard deviations. Following a major effort over the past few years, the BNL storage ring has been transported to and upgraded at Fermilab and recently started taking data to improve on the precision of E821.

    FNAL Muon g-2 studio

    In the BNL/Fermilab setup, a beam of protons enters a fixed target to create pions, which decay into muons with aligned spins. The muons are then transferred to the 14 m-diameter storage ring, which uses electrostatic focusing to provide vertical confinement, and their magnetic moments are measured as they precess in a magnetic field.

    The new J-PARC experiment, E34, proposes to measure muon g-2 with an eventual precision of 0.1 ppm by storing ultra-cold muons in a mere 0.66 m-diameter magnet, aiming to reach the BNL precision in a first phase. The muons are produced by laser-ionising muonium atoms (bound states of a positive muon and an electron), which, since they are created at rest, results in a muon beam with very little spread in the transverse direction – thus eliminating the need for electrostatic focusing.

    The ultracold muon beam is stored in a high-precision magnet where the spin-precession of muons is measured by detecting muon decays. This low-emittance technique, which allows a smaller magnet and lower muon energies, enables researchers to circumvent some of the dominant systematic uncertainties in the previous g-2 measurement. To avoid decay losses, the J-PARC approach requires muons to be accelerated via a conventional radio-frequency accelerator.

    In October 2017, a team comprising physicists from Japan, Korea and Russia successfully demonstrated the first acceleration of negative muonium ions, reaching an energy of 90 keV. The experiment was conducted using a radio-frequency quadrupole linac (RFQ) installed at a muon beamline at J-PARC, which is driven by a high-intensity pulsed proton beam. Negative muonium atoms were first accelerated electrostatically and then injected into the RFQ, after which they were guided to a detector through a transport beamline. The accelerated negative muonium atoms were identified from their time of flight: because a particle’s velocity at a given energy is uniquely determined from its mass, its type is identified by measuring the velocity (see figure).

    The researchers are now planning to further accelerate the beam from the RFQ. In addition to precise measurements in particle physics, the J-PARC result offers new muon-accelerator applications including the construction of a transmission muon microscope for use in materials and life-sciences research, says team member Masashi Otani of KEK laboratory. “Part of the construction of the experiment has started with partial funding, which includes the frontend muon beamline and detector. The experiment can start properly three years after full funding is provided.”

    Muon acceleration is also key to a potential muon collider and neutrino factory, for which it is proposed that the large, transverse emittance of the muon beam can be reduced using ionisation cooling (see Muons cooled for action).

    See the full article here .


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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN map

    CERN LHC Grand Tunnel

    CERN LHC particles

     
  • richardmitnick 4:36 pm on January 8, 2018 Permalink | Reply
    Tags: Accelerating science, , , Building collaborations, , , FNAL Muon g-2, , MUSE and NEWS are two grant programs by which nearly 150 European scientists come to Fermilab to help advance its research, MUSE and NEWS are two new endeavors at the DOE Office of Science’s FNAL,   

    From FNAL: “MUSE and NEWS are on the RISE” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    January 8, 2018
    No writer credit found

    MUSE and NEWS are two new endeavors at the DOE Office of Science’s Fermilab, the U.S.’s premier particle physics laboratory. And contrary to what some physics fans might infer, the acronyms don’t stand for science experiments.

    They’re two new bridge-building grant programs that are designed to enable scientists from Europe to conduct particle physics research at Fermilab.

    1
    Muon g-2 is one of the Fermilab experiments that European scientists work on through the MUSE agreement. Photo: Reidar Hahn

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment


    FNAL Muon g-2 studio

    RISE to the occasion

    MUSE and NEWS are two grant programs by which nearly 150 European scientists come to Fermilab to help advance its research, in particular on the laboratory’s muon experiments and superconducting accelerator technology. Their contributions total the equivalent of $15 million in salaried work.

    The European Commission H2020 research and innovation program provides funding for the NEWS and MUSE projects through the Marie Sklodowska-Curie Research and Innovation Staff Exchange (RISE) action. (The European Commission is the executive body of the European Union.)

    The RISE scheme promotes international and cross-sector collaboration through the exchange research and innovation staff and by sharing knowledge and ideas from research to market (and vice versa).

    “Everybody wins,” said Simone Donati of the University of Pisa, who is also a NEWS co-coordinator. “The European institutions benefit because they receive money to travel here. Fermilab benefits because it has placed several institutions into the networks. The people benefit. And the networks should last for a long time, even after the projects’ completion.”

    Building collaborations

    3
    MUSE exchange scientists also work on Mu2e. Photo: Reidar Hahn

    FNAL Mu2e solenoid


    FNAL Mu2e facility

    Accelerating science

    MUSE, which started in 2016, is coordinated by INFN researcher Simona Giovannella and supports roughly 70 scientists from universities and research institutes in Germany, Greece, Italy and the UK to work on Fermilab’s Mu2e and Muon g-2 experiments. The European scientists will contribute to an impressive 400 months’ worth of contributed work over four years to help further the cutting-edge particle detector technologies needed to look for hidden or rare particles predicted by theory but, as of now, never observed by experiment. Fermilab scientist Doug Glenzinski coordinates this activity at the lab.

    NEWS was proposed a year later, in 2016, to advance a number of fields in particle physics. Through NEWS, scientists from Germany, Greece, Italy and Sweden come to Fermilab to study muon physics and superconducting accelerator science. They also go to Caltech, NASA, SLAC National Accelerator Laboratory, and U.S. companies, as well as to the Japanese National Astronomical Observatory in Japan.

    Fermilab in particular will enjoy 100 months’ worth of contributed work over four years through NEWS, beginning in 2018. The roughly 60 visiting scientists will work on superconducting technologies for particle accelerators and detectors. Barzi coordinates this activity at Fermilab.

    (And in case you wondered: NEWS is short for “NEw WindowS on the universe and technological advancements from trilateral EU-US-Japan collaboration.” The MUSE acronym is more straightforward: “Muon campus in the U.S. and European contributions.” Acronymization is an art, not a science.)

    Reaching out through RISE

    3
    NEWS enables European scientists to work on superconducting accelerator and detector technologies at Fermilab. Photo: Reidar Hahn

    Outreach is a crucial component of participation in a RISE-funded program. MUSE and NEWS scientists at Fermilab are required to conduct science outreach in some way during their time at the lab. Many, for example, participate in the laboratory’s international summer students program, which was initially established by University of Pisa Professor Emeritus Giorgio Bellettini for visiting Italian university students in 1984.

    “The summer student program is just one example,” Donati said. “There are many other initiatives that we organize at Fermilab and other institutions, such as teaching seminars by experts in their field and physics nights at historical venues.”

    It’s all a part of the benefits-of-networks ethos in science, and for RISE in particular. The connections made in particle physics do more than advance research careers. They attract the next generation of scientists and benefit humanity.

    “RISE says, ‘We give you money to do your excellent research, and this research must not be confined within a library or laboratory,’” Donati said. “You have to show to the public that this is important, that it’s important for society, that people in science find good jobs so that the younger generations are encouraged to pursue a career in science.”

    MUSE and NEWS are just two manifestations of the principle, and Barzi expects to see a resulting expansion and strengthening of the research community.

    “We’re making practical use of a European funding agency for science, expanding our funding resources,” Barzi said. “Networks tend to increase because they keep branching out and branching out. They naturally expand because you involve people who are interested in that area of science, and they kind of naturally come to you.”

    She adds, “You can use your skills and knowledge to contribute outside your own narrow, specialized field. This is what I find most exciting.”

    Further details about RISE work plan 2018-2020 and the upcoming call for proposals is available online.

    See the full article 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
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  • richardmitnick 11:26 am on November 8, 2017 Permalink | Reply
    Tags: FNAL Muon g-2, , , , , , ,   

    From LBNL: “New Study: Scientists Narrow Down the Search for Dark Photons Using Decade-Old Particle Collider Data” 

    Berkeley Logo

    Berkeley Lab

    November 8, 2017
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 520-0843

    1
    The BaBar detector at SLAC National Accelerator Laboratory. (Credit: SLAC)

    SLAC BABAR

    In its final years of operation, a particle collider in Northern California was refocused to search for signs of new particles that might help fill in some big blanks in our understanding of the universe.

    A fresh analysis of this data, co-led by physicists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), limits some of the hiding places for one type of theorized particle – the dark photon, also known as the heavy photon – that was proposed to help explain the mystery of dark matter.

    The latest result, published in the journal Physical Review Letters by the roughly 240-member BaBar Collaboration, adds to results from a collection of previous experiments seeking, but not yet finding, the theorized dark photons.

    “Although it does not rule out the existence of dark photons, the BaBar results do limit where they can hide, and definitively rule out their explanation for another intriguing mystery associated with the property of the subatomic particle known as the muon,” said Michael Roney, BaBar spokesperson and University of Victoria professor.

    Dark matter, which accounts for an estimated 85 percent of the total mass of the universe, has only been observed by its gravitational interactions with normal matter. For example, the rotation rate of galaxies is much faster than expected based on their visible matter, suggesting there is “missing” mass that has so far remained invisible to us.

    So physicists have been working on theories and experiments to help explain what dark matter is made of – whether it is composed of undiscovered particles, for example, and whether there may be a hidden or “dark” force that governs the interactions of such particles among themselves and with visible matter. The dark photon, if it exists, has been put forward as a possible carrier of this dark force.

    Using data collected from 2006 to 2008 at SLAC National Accelerator Laboratory in Menlo Park, California, the analysis team scanned the recorded byproducts of particle collisions for signs of a single particle of light – a photon – devoid of associated particle processes.

    The BaBar experiment, which ran from 1999 to 2008 at SLAC, collected data from collisions of electrons with positrons, their positively charged antiparticles. The collider driving BaBar, called PEP-II, was built through a collaboration that included SLAC, Berkeley Lab, and Lawrence Livermore National Laboratory. At its peak, the BaBar Collaboration involved over 630 physicists from 13 countries.

    BaBar was originally designed to study the differences in the behavior between matter and antimatter involving a b-quark. Simultaneously with a competing experiment in Japan called Belle, BaBar confirmed the predictions of theorists and paved the way for the 2008 Nobel Prize.

    KEK Belle 2 detector, in Tsukuba, Ibaraki Prefecture, Japan

    Berkeley Lab physicist Pier Oddone proposed the idea for BaBar and Belle in 1987 while he was the Lab’s Physics division director.

    The latest analysis used about 10 percent of BaBar’s data – recorded in its final two years of operation. Its data collection was refocused on finding particles not accounted for in physics’ Standard Model – a sort of rulebook for what particles and forces make up the known universe.

    “BaBar performed an extensive campaign searching for dark sector particles, and this result will further constrain their existence,” said Bertrand Echenard, a research professor at Caltech who was instrumental in this effort.

    2
    This chart shows the search area (green) explored in an analysis of BaBar data where dark photon particles have not been found, compared with other experiments’ search areas. The red band shows the favored search area to determine whether dark photons are causing the so-called “g-2 anomaly,” and the white areas are among the unexplored territories for dark photons. (Credit: Muon g-2 Collaboration)

    In its final years of operation, a particle collider in Northern California was refocused to search for signs of new particles that might help fill in some big blanks in our understanding of the universe.

    A fresh analysis of this data, co-led by physicists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), limits some of the hiding places for one type of theorized particle – the dark photon, also known as the heavy photon – that was proposed to help explain the mystery of dark matter.

    The latest result, published in the journal Physical Review Letters by the roughly 240-member BaBar Collaboration, adds to results from a collection of previous experiments seeking, but not yet finding, the theorized dark photons.

    “Although it does not rule out the existence of dark photons, the BaBar results do limit where they can hide, and definitively rule out their explanation for another intriguing mystery associated with the property of the subatomic particle known as the muon,” said Michael Roney, BaBar spokesperson and University of Victoria professor.

    Dark matter, which accounts for an estimated 85 percent of the total mass of the universe, has only been observed by its gravitational interactions with normal matter. For example, the rotation rate of galaxies is much faster than expected based on their visible matter, suggesting there is “missing” mass that has so far remained invisible to us.

    So physicists have been working on theories and experiments to help explain what dark matter is made of – whether it is composed of undiscovered particles, for example, and whether there may be a hidden or “dark” force that governs the interactions of such particles among themselves and with visible matter. The dark photon, if it exists, has been put forward as a possible carrier of this dark force.

    Using data collected from 2006 to 2008 at SLAC National Accelerator Laboratory in Menlo Park, California, the analysis team scanned the recorded byproducts of particle collisions for signs of a single particle of light – a photon – devoid of associated particle processes.

    The BaBar experiment, which ran from 1999 to 2008 at SLAC, collected data from collisions of electrons with positrons, their positively charged antiparticles. The collider driving BaBar, called PEP-II, was built through a collaboration that included SLAC, Berkeley Lab, and Lawrence Livermore National Laboratory. At its peak, the BaBar Collaboration involved over 630 physicists from 13 countries.

    BaBar was originally designed to study the differences in the behavior between matter and antimatter involving a b-quark. Simultaneously with a competing experiment in Japan called Belle, BaBar confirmed the predictions of theorists and paved the way for the 2008 Nobel Prize. Berkeley Lab physicist Pier Oddone proposed the idea for BaBar and Belle in 1987 while he was the Lab’s Physics division director.

    The latest analysis used about 10 percent of BaBar’s data – recorded in its final two years of operation. Its data collection was refocused on finding particles not accounted for in physics’ Standard Model – a sort of rulebook for what particles and forces make up the known universe.

    “BaBar performed an extensive campaign searching for dark sector particles, and this result will further constrain their existence,” said Bertrand Echenard, a research professor at Caltech who was instrumental in this effort.
    Chart – This chart shows the search area (green) explored in an analysis of BaBar data where dark photon particles have not been found, compared with other experiments’ search areas. The red band shows the favored search area to determine whether dark photons are causing the so-called “g-2 anomaly,” and the white areas are among the unexplored territories for dark photons. (Credit: Muon g-2 Collaboration)

    This chart shows the search area (green) explored in an analysis of BaBar data where dark photon particles have not been found, compared with other experiments’ search areas. The red band shows the favored search area to determine whether dark photons are causing the so-called “g-2 anomaly,” and the white areas are among the unexplored territories for dark photons. (Credit: Muon g-2 Collaboration)

    Yury Kolomensky, a physicist in the Nuclear Science Division at Berkeley Lab and a faculty member in the Department of Physics at UC Berkeley, said, “The signature (of a dark photon) in the detector would be extremely simple: one high-energy photon, without any other activity.”

    A number of the dark photon theories predict that the associated dark matter particles would be invisible to the detector. The single photon, radiated from a beam particle, signals that an electron-positron collision has occurred and that the invisible dark photon decayed to the dark matter particles, revealing itself in the absence of any other accompanying energy.

    When physicists had proposed dark photons in 2009, it excited new interest in the physics community, and prompted a fresh look at BaBar’s data. Kolomensky supervised the data analysis, performed by UC Berkeley undergraduates Mark Derdzinski and Alexander Giuffrida.

    “Dark photons could bridge this hidden divide between dark matter and our world, so it would be exciting if we had seen it,” Kolomensky said.

    The dark photon has also been postulated to explain a discrepancy between the observation of a property of the muon spin and the value predicted for it in the Standard Model. Measuring this property with unprecedented precision is the goal of the Muon g-2 (pronounced gee-minus-two) Experiment at Fermi National Accelerator Laboratory [FNAL].

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment

    FNAL Muon g-2 studio

    Earlier measurements at Brookhaven National Laboratory had found that this property of muons – like a spinning top with a wobble that is ever-slightly off the norm – is off by about 0.0002 percent from what is expected. Dark photons were suggested as one possible particle candidate to explain this mystery, and a new round of experiments begun earlier this year should help to determine whether the anomaly is actually a discovery.

    The latest BaBar result, Kolomensky said, largely “rules out these dark photon theories as an explanation for the g-2 anomaly, effectively closing this particular window, but it also means there is something else driving the g-2 anomaly if it’s a real effect.”

    It’s a common and constant interplay between theory and experiments, with theory adjusting to new constraints set by experiments, and experiments seeking inspiration from new and adjusted theories to find the next proving grounds for testing out those theories.

    Scientists have been actively mining BaBar’s data, Roney said, to take advantage of the well-understood experimental conditions and detector to test new theoretical ideas.

    “Finding an explanation for dark matter is one of the most important challenges in physics today, and looking for dark photons was a natural way for BaBar to contribute,” Roney said, adding that many experiments in operation or planned around the world are seeking to address this problem.

    An upgrade of an experiment in Japan that is similar to BaBar, called Belle II, turns on next year. “Eventually, Belle II will produce 100 times more statistics compared to BaBar,” Kolomensky said. “Experiments like this can probe new theories and more states, effectively opening new possibilities for additional tests and measurements.”

    “Until Belle II has accumulated significant amounts of data, BaBar will continue for the next several years to yield new impactful results like this one,” Roney said.

    The study featured participation by the international BaBar collaboration, which includes researchers from about 66 institutions in the U.S., Canada, France, Spain, Italy, Norway, Germany, Russia, India, Saudi Arabia, U.K., the Netherlands, and Israel. The work was supported by the U.S. Department of Energy’s Office of Science and the National Science Foundation; the Natural Sciences and Engineering Research Council in Canada; CEA and CNRS-IN2P3 in France; BMBF and DFG in Germany; INFN in Italy; FOM in the Netherlands; NFR in Norway; MES in Russia; MINECO in Spain; STFC in the U.K.; and BSF in Israel and the U.S. Individuals involved with this study have received support from the Marie Curie EIF in the European Union, and the Alfred P. Sloan Foundation in the U.S.

    See the full article here .

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  • richardmitnick 1:15 pm on June 1, 2017 Permalink | Reply
    Tags: , , Brookhaven Lab, FNAL Muon g-2, Moving the magnet, ,   

    From Symmetry: “Muon magnet’s moment has arrived” 

    Symmetry Mag

    Symmetry

    06/01/17
    Andre Salles

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment

    1
    Muon g-2 experimental hall.Photo by Fermilab

    What do you get when you revive a beautiful 20-year-old physics machine, carefully transport it 3200 miles over land and sea to its new home, and then use it to probe strange happenings in a magnetic field? Hopefully you get new insights into the elementary particles that make up everything.

    The Muon g-2 experiment, located at the US Department of Energy’s Fermi National Accelerator Laboratory, has begun its quest for those insights.

    Take a 360-degree tour of the Muon g-2 experimental hall.

    On May 31, the 50-foot-wide superconducting electromagnet at the center of the experiment saw its first beam of muon particles from Fermilab’s accelerators, kicking off a three-year effort to measure just what happens to those particles when placed in a stunningly precise magnetic field. The answer could rewrite scientists’ picture of the universe and how it works.

    “The Muon g-2 experiment’s first beam truly signals the start of an important new research program at Fermilab, one that uses muon particles to look for rare and fascinating anomalies in nature,” says Fermilab Director Nigel Lockyer. “After years of preparation, I’m excited to see this experiment begin its search in earnest.”

    Getting to this point was a long road for Muon g-2, both figuratively and literally. The first generation of this experiment took place at Brookhaven National Laboratory in New York State in the late 1990s and early 2000s.


    The goal of the experiment was to precisely measure one property of the muon—the particles’ precession, or wobble, in a magnetic field. The final results were surprising, hinting at the presence of previously unknown phantom particles or forces affecting the muon’s properties.

    The new experiment at Fermilab will make use of the laboratory’s intense beam of muons to definitively answer the questions the Brookhaven experiment raised. And since it would have cost 10 times more to build a completely new machine at Brookhaven rather than move the magnet to Fermilab, the Muon g-2 team transported that large, fragile superconducting magnet in one piece from Long Island to the suburbs of Chicago in the summer of 2013.

    The magnet took a barge south around Florida, up the Tennessee-Tombigbee waterway and the Illinois River, and was then driven on a specially designed truck over three nights to Fermilab. And thanks to a GPS-powered map online, it collected thousands of fans over its journey, making it one of the most well-known electromagnets in the world.

    “Getting the magnet here was only half the battle,” says Chris Polly, project manager of the Muon g-2 experiment. “Since it arrived, the team here at Fermilab has been working around the clock installing detectors, building a control room and, for the past year, adjusting the uniformity of the magnetic field, which must be precisely known to an unprecedented level to obtain any new physics. It’s been a lot of work, but we’re ready now to really get started.”

    That work has included the creation of a new beamline to deliver a pure beam of muons to the ring, the installation of a host of instrumentation to measure both the magnetic field and the muons as they circulate within it, and a year-long process of “shimming” the magnet, inserting tiny pieces of metal by hand to shape the magnetic field. The field created by the magnet is now three times more uniform than the one it created at Brookhaven.

    Over the next few weeks the Muon g-2 team will test the equipment installed around the magnet, which will be storing and measuring muons for the first time in 16 years. Later this year, they will start taking science-quality data, and if their results confirm the anomaly first seen at Brookhaven, it will mean that the elegant picture of the universe that scientists have been working on for decades is incomplete, and that new particles or forces may be out there, waiting to be discovered.

    “It’s an exciting time for the whole team, and for physics,” says David Hertzog of the University of Washington, co-spokesperson of the Muon g-2 collaboration. “The magnet has been working, and working fantastically well. It won’t be long until we have our first results, and a better view through the window that the Brookhaven experiment opened for us.”

    See the full article here .

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  • richardmitnick 1:13 pm on April 16, 2017 Permalink | Reply
    Tags: , FNAL Muon g-2, , , , ,   

    From Nature: “Muons’ big moment could fuel new physics” 

    Nature Mag
    Nature

    11 April 2017
    Elizabeth Gibney

    1
    The Muon g-2 experiment will look for deviations from the standard model by measuring how muons wobble in a magnetic field. Credit: FNAL

    In the search for new physics, experiments based on high-energy collisions inside massive atom smashers are coming up empty-handed. So physicists are putting their faith in more-precise methods: less crash-and-grab and more watching-ways-of-wobbling. Next month, researchers in the United States will turn on one such experiment. It will make a super-accurate measurement of the way that muons, heavy cousins of electrons, behave in a magnetic field. And it could provide evidence of the existence of entirely new particles.

    The particles hunted by the new experiment, at the Fermi National Laboratory in Batavia, Illinois, comprise part of the virtual soup that surrounds and interacts with all forms of matter. Quantum theory says that short-lived virtual particles constantly ‘blip’ in and out of existence. Physicists already account for the effects of known virtual particles, such as photons and quarks. But the virtual soup might have mysterious, and as yet unidentified, ingredients. And muons could be particularly sensitive to them.

    The new Muon g−2 experiment will measure this sensitivity with unparalleled precision. And in doing so, it will reanalyse a muon anomaly that has puzzled physicists for more than a decade. If the experiment confirms that the anomaly is real, then the most likely explanation is that it is caused by virtual particles that do not appear in the existing physics playbook — the standard model.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    2
    Adapted from go.nature.com/2naoxaw

    “It would be the first direct evidence of not only physics beyond the standard model, but of entirely new particles,” says Dominik Stöckinger, a theorist at the Technical University of Dresden, Germany, and a member of the Muon g−2 collaboration.

    Physicists are crying out for a successor to the standard model — a theory that has been fantastically successful yet is known to be incomplete because it fails to account for many phenomena, such as the existence of dark matter. Experiments at the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics lab near Geneva, Switzerland, have not revealed a specific chink, despite performing above expectation and carrying out hundreds of searches for physics beyond the standard model. The muon anomaly is one of only a handful of leads that physicists have.

    Measurements of the muon’s magnetic moment — a fundamental property that relates to the particle’s inherent magnetism — could hold the key, because it is tweaked by interactions with virtual particles. When last measured 15 years ago at the Brookhaven National Laboratory in New York, the muon’s magnetic moment was larger than theory predicts.

    BNL RHIC Campus

    BNL/RHIC

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment

    Physicists think that interaction with unknown particles, perhaps those envisaged by a theory called supersymmetry, might have caused this anomaly.

    Other possible explanations are a statistical fluke, or a flaw in the theorists᾽ standard-model calculation, which combines the complex effects of known particles. But that is becoming less likely, says Stöckinger, who says that new calculation methods and experimental cross-checks make the theoretical side much more robust than it was 15 years ago.

    “With this tantalizing result from Brookhaven, you really have to do a better experiment,” says Lee Roberts, a physicist at Boston University in Massachusetts, who is joint leader of the Muon g−2 experiment. The Fermilab set-up will use 20 times the number of muons used in the Brookhaven experiment to shrink uncertainty by a factor of 4. “If we agree, but with much smaller error, that will show definitively that there’s some particle that hasn’t been observed anywhere else,” he says.

    To probe the muons, Fermilab physicists will inject the particles into a magnetic field contained in a ring some 14 metres across. Each particle has a magnetic property called spin, which is analogous to Earth spinning on its axis. As the muons travel around the ring at close to the speed of light, their axes of rotation wobble in the field, like off-kilter spinning tops. Combining this precession rate with a measurement of the magnetic field gives the particles’ magnetic moment.

    Since the Brookhaven result, some popular explanations for the anomaly — including effects of hypothetical dark photons — seem to have been ruled out by other experiments, says Stöckinger. “But if you look at the whole range of scenarios for physics beyond the standard model, there are many possibilities.”

    3
    Fermilab is the home of the Muon g−2 experiment.

    Although a positive result would give little indication of exactly what the new particles are, it would provide clues to how other experiments might pin them down. If the relatively large Brookhaven discrepancy is maintained, it can only come from relatively light particles, which should be within reach of the LHC, says Stöckinger, even if they interact so rarely that it takes years for them to emerge.

    Indeed, the desire to build on previous findings is so strong that to avoid possible bias, Fermilab experimenters will process their incoming results ‘blind’ and apply a different offset to each of two measurements that combine to give the magnetic moment. Only once the offsets are revealed will anyone know whether they have proof of new particles hiding in the quantum soup. “Until then nobody knows what the answer is,” says Roberts. “It will be an exciting moment.”

    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 1:02 pm on June 28, 2016 Permalink | Reply
    Tags: , Brookhaven E821 Muon (g-2), FNAL Muon g-2, ,   

    From Symmetry: “Preparing for their magnetic moment” 

    Symmetry Mag

    Symmetry

    06/28/16
    Andre Salles

    1
    Cindy Arnold, Fermilab

    Scientists are using a plastic robot and hair-thin pieces of metal to ready a magnet that will hunt for new physics.

    Three summers ago, a team of scientists and engineers on the Muon g-2 experiment moved a 52-foot-wide circular magnet 3200 miles over land and sea. It traveled in one piece without twisting more than a couple of millimeters, lest the fragile coils inside irreparably break. It was an astonishing feat that took years to plan and immense skill to execute.

    FNAL Muon g-2 studio
    FNAL Muon g-2 studio

    As it turns out, that was the easy part.

    The hard part—creating a magnetic field so precise that even subatomic particles see it as perfectly smooth—has been under way for seven months. It’s a labor-intensive process that has inspired scientists to create clever, often low-tech solutions to unique problems, working from a road map written 30 years ago as they drive forward into the unknown.

    The goal of Muon g-2 is to follow up on a similar experiment conducted at the US Department of Energy’s Brookhaven National Laboratory in New York in the 1990s.

    2
    E821 Muon (g-2) At Brookhaven

    Scientists there built an extraordinary machine that generated a near-perfect magnetic field into which they fired a beam of particles called muons. The magnetic ring serves as a racetrack for the muons, and they zoom around it for as long as they exist—usually about 64 millionths of a second.

    That’s a blink of an eye, but it’s enough time to measure a particular property: the precession frequency of the muons as they hustle around the magnetic field. And when Brookhaven scientists took those measurements, they found something different than the Standard Model, our picture of the universe, predicted they would. They didn’t quite capture enough data to claim a definitive discovery, but the hints were tantalizing.

    Now, 30 years later, some of those same scientists—and dozens of others, from 34 institutions around the world—are conducting a similar experiment with the same magnet, but fed by a more powerful beam of muons at the US Department of Energy’s Fermi National Accelerator Laboratory in Illinois. Moving that magnet from New York caused quite a stir among the science-interested public, but that’s nothing compared with what a discovery from the Muon g-2 experiment would cause.

    “We’re trying to determine if the muon really is behaving differently than expected,” says Dave Hertzog of the University of Washington, one of the spokespeople of the Muon g-2 experiment. “And, if so, that would suggest either new particles popping in and out of the vacuum, or new subatomic forces at work. More likely, it might just be something no one has thought of yet. In any case, it’s all very exciting.”

    Shimming to reduce shimmy

    To start making these measurements, the magnetic field needs to be the same all the way around the ring so that, wherever the muons are in the circle, they will see the same pathway. That’s where Brendan Kiburg of Fermilab and a group of a dozen scientists, post-docs and students come in. For the past six months, they have been “shimming” the magnetic ring, shaping it to an almost inconceivably exact level.

    “The primary goal of shimming is to make the magnetic field as uniform as possible,” Kiburg says. “The muons act like spinning tops, precessing at a rate proportional to the magnetic field. If a section of the field is a little higher or a little lower, the muon sees that, and will go faster or slower.”

    Since the idea is to measure the precession rate to an extremely precise degree, the team needs to shape the magnetic field to a similar degree of uniformity. They want it to vary by no more than ten parts in a billion per centimeter. To put that in perspective, that’s like wanting a variation of no more than one second in nearly 32 years, or one sheet in a roll of toilet paper stretching from New York to London.

    How do they do this? First, they need to measure the field they have. With a powerful electromagnet that will affect any metal object inside it, that’s pretty tricky. The solution is a marriage of high-tech and low-tech: a cart made of sturdy plastic and quartz, moved by a pulley attached to a motor and continuously tracked by a laser. On this cart are probes filled with petroleum jelly, with sensors measuring the rate at which the jelly’s protons spin in the magnetic field.

    The laser can record the position of the cart to 25 microns, half the width of a human hair. Other sensors measure how far apart the top and bottom of the cart are to the magnet, to the micron.

    “The cart moves through the field as it is pulled around the ring,” Kiburg says. “It takes between two and two-and-a-half hours to go around the ring. There are more than 1500 locations around the path, and it stops every three centimeters for a short moment while the field is precisely measured in each location. We then stitch those measurements into a full map of the magnetic field.”

    Erik Swanson of the University of Washington is the run coordinator for this effort, meaning he directs the team as they measure the field and perform the manually intensive shimming. He also designed the new magnetic resonance probes that measure the field, upgrading them from the technology used at Brookhaven.

    “They’re functionally the same,” he says of the probes, “but the Brookhaven experiment started in the 1990s, and the old probes were designed before that. Any electronics that old, there’s the potential that they will stop working.”

    Swanson says that the accuracy to which the team has had to position the magnet’s iron pieces to achieve the desired magnetic field surprised even him. When scientists first turned the magnet on in October, the field, measured at different places around the ring, varied by as much as 1400 parts per million. That may seem smooth, but to a tiny muon it looks like a mountain range of obstacles. In order to even it out, the Muon g-2 team makes hundreds of minuscule adjustments by hand.


    Access mp4 video here .

    Physical physics

    Stationed around the ring are about 1000 knobs that control the ways the field could become non-uniform. But when that isn’t enough, the field can be shaped by taking parts of the magnet apart and inserting extremely small pieces of steel called shims, changing the field by thousandths of an inch.

    There are 12 sections of the magnet, and it takes an entire day to adjust just one of those sections.

    This process relies on simulations, calibrations and iterations, and with each cycle the team inches forward toward their goal, guided by mathematical predictions. Once they’re done with the process of carefully inserting these shims, some as thin as 12.5 microns, they reassemble the magnet and measure the field again, starting the process over, refining and learning as they go.

    “It’s fascinating to me how hard such a simple-seeming problem can be,” says Matthias Smith of the University of Washington, one of the students who helped design the plastic measuring robot. “We’re making very minute adjustments because this is a puzzle that can go together in multiple ways. It’s very complex.”

    His colleague Rachel Osofsky, also of the University of Washington, agrees. Osofsky has helped put in more than 800 shims around the magnet, and says she enjoys the hands-on and collaborative nature of the work.

    “When I first came aboard, I knew I’d be spending time working on the magnet, but I didn’t know what that meant,” she says. “You get your hands dirty, really dirty, and then measure the field to see what you did. Students later will read the reports we’re writing now and refer to them. It’s exciting.”

    Similarly, the Muon g-2 team is constantly consulting the work of their predecessors who conducted the Brookhaven experiment, making improvements where they can. (One upgrade that may not be obvious is the very building that the experiment is housed in, which keeps the temperature steadier than the one used at Brookhaven and reduces shape changes in the magnet itself.)

    Kiburg says the Muon g-2 team should be comfortable with the shape of the magnetic field sometime this summer. With the experiment’s beamline under construction and the detectors to be installed, the collaboration should be ready to start measuring particles by next summer. Swanson says that while the effort has been intense, it has also been inspiring.

    “It’s a big challenge to figure out how to do all this right,” he says. “But if you know scientists, when a challenge seems almost impossible, that’s the one we all go for.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
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