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  • richardmitnick 9:51 am on December 19, 2014 Permalink | Reply
    Tags: Accelerator Science,   

    From CERN: “Long Shutdown 1: Exciting times ahead” 

    CERN New Masthead

    Posted by Cian O’Luanaigh on 8 Feb 2013.
    Updated 11 Dec 2014
    Caroline Duc

    The Large Hadron Collider (LHC) has provided physicists with a huge quantity of data to analyse since the first physics run in 2009. Now it’s time for the machine, along with CERN’s other accelerators, to get a facelift. “Long Shutdown 1″ (LS1) will begin on 14 February 2013, but this doesn’t mean that life at CERN will be any less rich and exciting. Although there will be no collisions for a period of almost two years, the whole CERN site will be a hive of activity, with large-scale work under way to modernize the infrastructure and prepare the LHC for operation at higher energy.

    1
    Over 10,000 high-current splices between LHC magnets will be opened and consolidated during the first Long Shutdown of the LHC. This image shows their installation in 2007 (Image: CERN)

    “A whole series of renovation work will be carried out around the LHC during LS1,” says Simon Baird, deputy head of the Engineering department. “The key driver is of course the consolidation of the 10,170 high-current splices (link is external) between the superconducting magnets. The teams will start by opening up the 1695 interconnections between each of the cryostats of the main magnets. They will repair and consolidate around 500 interconnections simultaneously. The maintenance work will gradually cover the entire 27-kilometre circumference of the LHC.” The LHC will be upgraded as well as renovated during the period concerned. In the framework of the Radiation to Electronics project (R2E), sensitive electronic equipment protection will be optimized by relocating the equipment or by adding shielding.

    The work will by no means be confined to the LHC. Major renovation work is scheduled, for example, for the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS). During LS1 the upgrade of the PS access control system, which includes the installation of 25 new biometrically controlled access points, will continue. The whole tunnel ventilation system will also be dismantled and replaced, with 25 air-handling units representing a cumulated flow rate of 576,000 cubic metres per hour to be installed around the accelerator’s 628-metre circumference. Meanwhile, at the SPS, about 100 kilometres of radiation-damaged cables used in the instrumentation and control systems will be removed or replaced.

    CERN will take advantage of LS1 to improve the installations connected with the experiments, accelerators, electronics, and so on, with a view to a spectacular resumption of its main activities after the shutdown. While the shutdown work is in progress, life at the laboratory will be anything but boring. Stay tuned to keep abreast of all the developments.

    See the full article here.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

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    CERN LHC New

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    Quantum Diaries

     
  • richardmitnick 1:27 pm on December 18, 2014 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From FNAL:- “Frontier Science Result: DZero Measuring the strange sea with silicon” 

    FNAL Home


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

    Thursday, Dec. 18, 2014
    Leo Bellantoni

    Our last DZero result began like so:

    FNAL DZero
    DZero

    “The parts inside of a proton are called, in a not terribly imaginative terminology, partons. The partons that we tend to think of first and foremost are quarks — two up quarks and a down quark in each proton — but there are other kinds of partons as well.”

    This time, we start in the same place — with those unimaginatively named partons. There are three types.

    The first type comprises those alluded to above: quarks. The two up quarks and one down quark that make up protons are called valence quarks. They determine the electrical charge of the proton. There are six flavors of quark, and all the different combinations of three out of the six correspond to a particle of a specific type, called a baryon. (Well, almost. Top flavored quarks decay so quickly they never form a particle.)

    The second type of parton is the gluon. Gluons hold the quarks inside the proton together and are the mediators of the strong nuclear force. Just as electromagnetic energy comes in point-like units called photons, so energy of the strong nuclear force comes in units of the gluon.

    The third type of parton is the sea quark. A gluon can split into a quark-antiquark pair that exists for a fleetingly short time (10-24 seconds or less) before reforming back into a gluon.

    Sea quarks can be of any flavor. They very often are up or down quarks, just like the valence quarks. But they can also be strange quarks, and strange quarks do not exist as valence quarks in protons. A reaction with a strange quark in the initial state lets you measure these strange sea quarks in proton collisions.

    The reaction involves the collision of a strange sea quark from one proton (or antiproton) with a gluon from an antiproton (or proton) to produce a W boson and a charm quark. The charm quark, when produced with a large momentum transverse to the direction of the initial collision, will produce a narrow spray of particles all moving in roughly the same direction. Such a particle spray is called a jet. Because the charm quark will travel a few millimeters before decaying, the fact that there was a charm quark producing the jet can be inferred using the silicon based microstrip tracking detector at the very center of the DZero detector.

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    Top quark and anti top quark pair decaying into jets, visible as collimated collections of particle tracks, and other fermions in the CDF detector at Tevatron.

    FNAL CDF
    CDF

    FNALTevatron
    Tevatron map

    Silicon technology also helps identify jets produced from bottom flavored quarks. In fact, bottom quark jets are easier to find than charm quark jets. Measuring the production of bottom quark jets in events with a W boson provides important information about the nonvalence partons — specifically, gluons — of the proton.

    DZero has recently measured the production of both charm and bottom jets when a W boson is also produced. The new measurement uses more data than earlier analyses, and for the first time, we obtain information about the production (with a W) of charm and bottom jets that are produced with different momenta transverse to the collision axis. How the production varies with the transverse momentum is a valuable measurement tool to understand the various subprocesses at work. This is also the first measurement of charm-W production that relies upon the silicon microstrip tracking technology; previous measurements were based on less effective techniques.

    —Leo Bellantoni

    See the full article here.

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    Fermilab Campus

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

     
  • richardmitnick 1:30 pm on December 17, 2014 Permalink | Reply
    Tags: Accelerator Science, , ,   

    From Symmetry: “LHC filled with liquid helium” 

    Symmetry

    December 17, 2014
    Sarah Charley

    The Large Hadron Collider is now cooled to nearly its operational temperature.

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

    The Large Hadron Collider isn’t just a cool particle accelerator. It’s the coldest.

    Last week the cryogenics team at CERN finished filling the eight curved sections of the LHC with liquid helium. The LHC ring is now cooled to below 4 kelvin (minus 452 degrees Fahrenheit).

    ice
    Photo by Maximilien Brice, CERN

    This cool-down is an important milestone in preparing the LHC for its spring 2015 restart, after which physicists plan to use it to produce the highest-energy particle collisions ever achieved on Earth.

    “We are delighted that the LHC is now cold again,” says Beate Heinemann, the deputy leader of the ATLAS experiment and a physicist with the University of California, Berkeley, and Lawrence Berkeley National Laboratory. “We are getting very excited about the high-energy run starting in spring next year, which will open the possibility of finding new particles which were just out of reach.”

    The LHC uses more than 1000 superconducting dipole magnets to bend high-energy particles around its circumference. These superconducting magnets are made from a special material that, when cooled close to absolute zero (minus 460 degrees Fahrenheit), can maintain a high electrical current with zero electrical resistance.

    “These magnets have to produce an extremely strong magnetic field to bend the particles, which are moving at very close to the speed of light,” says Mike Lamont, the head of LHC operations. “The magnets are powered with high electrical currents whenever beam is circulating. Room-temperature electromagnets would be unable to support the currents required.”

    To get the 16 miles of LHC magnets close to absolute zero, engineers slowly inject helium into a special cryogenic system surrounding the magnets and gradually reduce the temperature over the course of several months at a rate of one sector cooled per month. As the temperature drops, the helium becomes liquid and acts as a cold shell to keep the magnets at their operational temperature.

    “Helium is a special element because it only becomes a liquid below 5 kelvin,” says Laurent Tavian, the group leader of the CERN cryogenics team. “It is also the only element which is not solid at very low temperature, and it is naturally inert—meaning we can easily store it and never have to worry about it becoming flammable.”

    The first sector cool-down started in May 2014. Engineers first pre-cooled the helium using 9000 metric tons of liquid nitrogen. After the pre-cooling, engineers injected the helium into the accelerator.

    “Filling the entire accelerator requires 130 metric tons of helium, which we received from our supplier at a rate of around one truckload every week,” Tavian says.

    In January CERN engineers plan to have the entire accelerator cooled to its nominal operating temperature of 1.9 kelvin (minus 456 degrees Fahrenheit), colder than outer space.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 2:41 pm on December 16, 2014 Permalink | Reply
    Tags: Accelerator Science, , Boston University, , , ,   

    From BU: “Trigger Happy” 

    Boston University Bloc

    Boston University

    December 1, 2014
    Barbara Moran

    Physicist Tulika Bose talks about smashing protons to find new physics

    tb
    Tulika Bose, trigger coordinator for the Compact Muon Solenoid experiment at the Large Hadron Collider in Switzerland. “Trigger meetings are dramatic places,” she says. Photo by Jackie Ricciardi

    Tulika Bose is a science detective. A trigger-happy, atom-smashing, big question-asking physicist, who spends her days sifting though scraps of proton collisions for clues about the universe.

    Bose, an assistant professor of physics at Boston University’s College of Arts & Sciences, works at the Large Hadron Collider (LHC) in Switzerland, one of the most powerful particle accelerators ever built. The LHC smashes protons together 40 million times a second, and physicists like Bose sort through the wreckage. Bose is looking for particles (or their remains) that will substantiate (or dismiss) new theories that solve mysteries about the Big Bang and the nature of matter.

    In September 2014, Bose was appointed trigger coordinator for the Compact Muon Solenoid (or CMS) experiment at the LHC. She spoke with BU Research about what all those words mean, and why we should bother looking for “new physics” when the old physics seems to work just fine.

    c
    CMS

    BU Research: You were recently appointed the “trigger coordinator” for something called the CMS experiment. Can you explain what that is?

    Bose: Sure! At the LHC, we collide protons with protons to see what comes out of the collision, trying to find new particles and new physics. There are four major experiments and CMS is one of them. The name stands for Compact Muon Solenoid—a solenoid is a type of magnet, hence “solenoid” in the name. It’s a particle detector.

    How big is it?

    15 meters high (that’s about 50 feet) and 15 meters wide. A person next to it looks like a tiny little person.

    Then why is it called “compact”? It doesn’t seem very compact!

    Very good question. It’s a relative word, because it’s compact in comparison to another experiment, Atlas. Atlas is larger but less dense. CMS is more compact and dense.

    CERN ATLAS New
    ATLAS

    How does it all work?

    The LHC is like a huge racetrack. The protons go along in one direction, and then another beam of protons goes along in the other direction. Magnets bend them in a circular path. And most of the time these two beams are kept separated, except at four positions within this ring, where we have detectors with a different kind of magnet, which focuses the two beams together. And exactly at that point where this happens—where the two beams come together—is our CMS detector. The collision is happening right in the middle of the detector.

    How many protons collide?

    The beam has about 2,800 “bunches,” and a bunch has about 1,011 protons. So it’s a very intense bunch. But the collision point is very, very tiny, because the closer you can squeeze them, the more likely it is that an interesting collision will occur.

    How often do you collide them?

    The collisions are supposed to happen every 25 nanoseconds, which means—

    Continuously? All day?

    Yes, so 40 million times a second.

    That’s so much data!

    Yes, exactly. That’s the problem.

    I thought you did it, like, once a month or something.

    No. This is happening 40 million times a second and running over extended periods of time. Of course, I should clarify that for the past run, we ran at half that frequency. It was only 20 million times a second. But when we start taking data next year, it will be 40 million times a second. And this is the challenge. We just don’t have the kind of technology or the money to be writing out all of this data.

    What does it mean to “write out” data?

    Selecting and writing them to disk, so we can analyze it later. We need to cut down to a rate which is more manageable; I would say a few hundred events per second—at most, 1,000 events per second. So you want to go from 40 million times to 1,000. This has to be done in real time, and that’s where the trigger comes in. It’s literally a filter, or you’re “triggering” on interesting events. That’s where the name comes from.

    Now I get it—so you set up the filter beforehand?

    You set up the filter beforehand, and the filter fires every time an interesting event comes along. So that’s the trigger firing on something interesting.

    So it sees something interesting, it fires, and then that data is written.

    Right.

    And you’re the one who figures out the triggers!

    Yes! I lead the team that figures this out. It’s challenging, because whatever you say “no” to is literally going into the trash.

    That would be a terrible feeling.

    Yes. You want to make sure that all of the new physics, and the fun stuff, is not going into the trash. So we have a complicated trigger system. At the very first level, it makes some coarse decisions: Does this event have an electron? Does this event have a muon? Does the muon have a certain momentum? Does the electron have a certain momentum?

    And the reason it’s looking for those things is because those things would be boring? Or interesting?

    Muons and electrons are subatomic particles that are predicted to appear when certain other particles decay. We initially start with protons colliding with protons, so if energetic muons and electrons are produced, it indicates an interesting event. So the Level 1 part of the trigger has about three microseconds to make a decision. It doesn’t do detailed calculations. It doesn’t have that luxury. It just says, “This event seems interesting enough. I’m going to keep it.”

    Then comes the second level of the triggering system, which is called the High Level trigger. And this is essentially algorithms, which are trying to make more of an informed decision. They have a little bit more time, about 200 milliseconds per event, and can do some more detailed calculations. They can obtain the momentum with better resolution. They can try to figure out if two muons that they see come from a certain particle, which has a certain mass. Of course, all of this assumes that we understand what the new physics will be, which we don’t. This is the part that keeps people awake at night.

    You keep mentioning the “new” physics. What’s wrong with the old physics?

    It goes back to what’s called the Standard Model of particle physics. It’s essentially a set of very elegant equations that describe our current understanding of the universe. So we know, for example, that there are these light particles: the leptons, electrons, muons, taus; and associated with each one of these is a neutral particle called the neutrino. We also know that there are generations of quarks: there is up, down, strange, charm, bottom and top—or beauty and truth, as they’re sometimes called.

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

    We know all these very well. We also know that there are these forces, such as the magnetic force, the weak force, the strong force, and then the gravitational force. Now, each of these forces has an associated particle. One that is predicted, for example, is the graviton, which is a carrier of the gravitational force.

    Now, going back to your question: Why are we interested in other theories? The problem is that the Standard Model leaves us with some things that are not explained very well. Firstly, gravity. The Standard Model doesn’t quite include gravity in this full picture. And the carrier of gravity, which is this hypothetical particle called the graviton, we haven’t seen it. So the Standard Model does not include gravity, and that is something which people are not happy about, naturally.

    I can imagine.

    Then the other two big mysteries. At the very creation of the universe, right after the Big Bang, we had equal amounts of matter and antimatter. However, everything we see around us is primarily matter. So where has all the antimatter gone? Then the other big issue is that a large fraction of the universe is what’s called dark matter. Now, what is dark matter, really? Again, the Standard Model doesn’t quite explain that.

    So, to answer all of these big questions, you have to study these little tiny things.

    Yes, these big questions are driving the kind of physics we’re doing. These new theories, which try to answer these big questions, have various predictions about new particles, so we are actively searching for these new particles.

    Why do you like designing triggers?

    It’s a lot of responsibility, making sure that you’re not making a wrong decision. So I’ve always liked challenges. And these are very, very complicated detectors. And things can naturally go wrong in some part of the detector, and the first place this shows up is at the trigger. If you have bad electronics in a certain part of the detector, it will, for example, just start firing all the time. And so you will see it because the trigger rates will just go spiking up.

    And you’ll go, “Oh my God, we just found the new physics! Oh, never mind, we didn’t.”

    Exactly. This has happened a number of times. You get very excited because you start seeing spikes, and then you find out that no, this was faulty electronics.

    And then, for some reason, the people who work on the trigger are a certain kind of people. They are very passionate, they’re very dramatic, and the trigger meetings are dramatic places. People say, “I want certain kinds of triggers for my physics group, and you’ve got to give it to me or else I can’t do anything.”

    I had no idea that it was so operatic.

    [laugh] It’s always been like that. So it’s fun.

    See the full article here.

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  • richardmitnick 5:21 am on December 15, 2014 Permalink | Reply
    Tags: Accelerator Science, , , ,   

    From CERN: “CERN’s Large Hadron Collider gears up for run 2″ 

    CERN New Masthead

    12 Dec 2014
    Cian O’Luanaigh

    CERN today announced at the 174th session of the CERN Council that the Large Hadron Collider (LHC) is gearing up for its second three-year run. The LHC is the largest and most powerful particle accelerator in the world and the whole 27-kilometre superconducting machine is now almost cooled to its nominal operating temperature of 1.9 degrees above absolute zero. All teams are at work to get the LHC back online and the CERN Control Centre is in full swing to carry out all the requested tests before circulating proton beams again in March 2015. Run 2 of the LHC follows a 2-year technical stop that prepared the machine for running at almost double the energy of the LHC’s first run.

    lhc
    The Large Hadron Collider is preparing for running at higher energy in 2015 (Image: Maximilen Brice/CERN)

    “With this new energy level, the LHC will open new horizons for physics and for future discoveries,” says CERN Director-General Rolf Heuer. “I’m looking forward to seeing what nature has in store for us”.

    For the first time on 9 December 2014, the magnets of one sector of the LHC, one eighth of the ring, were successfully powered to the level needed for beams to reach 6.5 TeV, the operating energy for run 2. The goal for 2015 will be to run with two proton beams in order to produce 13 TeV collisions, an energy never achieved by any accelerator in the past.

    “After the huge amount of work done over the last two years, the LHC is almost like a new machine,” said CERN’s Director for Accelerators and Technology Frédérick Bordry. “Restarting this extraordinary accelerator is far from routine. Nevertheless, I’m confident that we will be on schedule to provide collisions to the LHC experiments by May 2015”.

    ALICE, ATLAS, CMS and LHCb, the four large experiments of the LHC, are also undergoing major preparatory work for run 2, after the long shutdown during which important programmes for maintenance and improvements were achieved. They will now enter their final commissioning phase.

    See the full article here.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New

    LHC particles

    Quantum Diaries

     
  • richardmitnick 5:22 pm on December 10, 2014 Permalink | Reply
    Tags: Accelerator Science, , ,   

    From Symmetry: “First LHC magnets prepped for restart” 

    Symmetry

    December 10, 2014
    Sarah Charley

    A first set of superconducting magnets has passed the test and is ready for the Large Hadron Collider to restart in spring.

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

    This week, one-eighth of the LHC dipole magnets reached the energy they’ll need to operate in 2015.

    m
    Photo by Anna Pantelia, CERN

    Engineers at CERN powered 154 superconducting magnets to a current of around 11,000 amps. This is about a thousand times greater than an average household appliance and is required to make the 50-foot-long electromagnets powerful enough to bend particles moving close to the speed of light around the curves of the LHC.

    “Over the summer we plan to ramp up the LHC to the highest energy ever achieved in a collider experiment,” says Mirko Pojer, an LHC engineer-in-charge and co-leader of the magnet re-commissioning team. “But before we do that, we need to make sure that our magnets are primed and ready for the job.”

    From 2010 to 2013, the LHC produced proton-proton collisions of up to 8 trillion electronvolts. This first run allowed physicist to probe a previously inaccessible realm of physics and discover the Higgs boson. But the LHC is designed to operate at even higher energies, and physicists are eager to see what might be hiding just out of reach.

    “We had a very successful first run and made a huge discovery, but we want to keep probing,” says Greg Rakness, a UCLA researcher and CMS run coordinator. “The exciting thing about the next run is that we have no idea what we could find, because we have never been able to access this energy realm before.”

    To prepare the LHC for 13 trillion electronvolt proton-proton collisions, CERN shut down the machine for almost two years for upgrades and repairs. This involved reinforcing almost 1700 magnet interconnections, including more than 10,000 superconducting splices.

    Now that that work is completed, engineers are putting the LHC magnets through a strenuous training program. Like Rocky Balboa prepping for a big fight, the magnets must be pushed repeatedly to the limits of their operation. This will prime them for the strenuous running conditions of the LHC.

    The LHC magnets are superconducting, which means that when they are cooled down, current passes through them with zero electrical resistance. During powering, current is gradually increased in the magnetic coils, which sometimes generates tiny movements in the superconductor. These movements create friction, which in turn locally heats up the superconductor and makes it quench—or suddenly return to a non-superconducting state. When this occurs, the circuit is switched off and its energy is absorbed by huge resistors.

    “By purposefully making the magnets quench, we can literally ‘shake out’ any unresolved tension in the coils and prep the magnets to hold a high current without losing their superconducting superpowers,” says Matteo Solfaroli, an LHC engineer-in-charge and co-leader of the commissioning team. “This is a necessary part of prepping the accelerator for the restart so that the magnets don’t quench while we are running the beam.”

    The magnets in all the other sectors will undergo similar training before being ready for operation. Many other tests will follow before beams can circulate in the LHC once more, next spring.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:10 pm on December 9, 2014 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From FNAL: “Digging begins for Muon g-2 and Mu2e beamlines” 


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

    Tuesday, Dec. 9, 2014
    Rich Blaustein

    This month construction has commenced on beamline tunnel extensions for Fermilab’s two muon experiments, Mu2e and Muon g-2.

    2
    A team of physicists from all over the world, including postdocal researchers and graduate and undergraduate students, are working together to design, test, and build the Mu2e experiment. The Mu2e Collaboration is comprised of over one hundred physicists and continues to grow.

    w
    Mu2e will have the ability to indirectly probe energy scales well beyond the terascale being explored at the LHC. At these higher energies the effects of new particles or new forces may become evident and may provide evidence that the four known forces that govern particle interations – the gravitational, electromagnetic, weak and strong forces – unify at some ultra-high energy. (Credit: symmetry magazine/Sandbox Studio)

    t
    The Mu2e detector is a particle physics detector embedded in a series of superconducting magnets. The magnets are designed to create a low-energy muon beam that can be stopped in a thin aluminum stopping target. The magnets also provide a constant magnetic field in the detector region that allows the momentum of the conversion electrons to be accurately determined. These superconducting magnets are big. The first, to the left, is about 12 feet long at 4.5 Tesla; the middle, S-shaped section about 40 feet along the curve at about 2 Tesla, and the third about 30 ft long and almost six feet across at 1 Tesla. The Earth’s field, for comparison, is 0.0006 Tesla.
    (Credit: symmetry magazine)

    g2
    Muon g-2 (pronounced gee minus two) will use Fermilab’s powerful accelerators to explore the interactions of short-lived particles known as muons with a strong magnetic field in “empty” space. Scientists know that even in a vacuum, space is never empty. Instead, it is filled with an invisible sea of virtual particles that—in accordance with the laws of quantum physics—pop in and out of existence for incredibly short moments of time. Scientists can test the presence and nature of these virtual particles with particle beams traveling in a magnetic field.

    In the area of the current Delivery Ring (the former Antiproton Debuncher), southwest of the Booster, the existing beam tunnel will be extended approximately 200 feet, at which point it will branch in two separate directions. The Muon g-2 tunnel, about 75 feet long, will terminate in the MC-1 Building, which houses the experiment’s muon storage ring. The Mu2e tunnel, around 550 feet long, will head toward a new building to be constructed for the experiment. Construction is expected to take one year. The start of the construction of the Mu2e building is planned for 2015.

    g
    Fermilab has begun construction on new beamlines for its muon programs, Muon g-2 and Mu2e. Image: Fermilab

    Digging for the tunnels began this month. Part of Kautz Road will become permanently inaccessible, with a detour from South Booster Road and Indian Creek Road serving as the new road.

    Fermilab Accelerator Division physicist Mary Convery, who oversees the Muon Campus program, coordinated the tunnel designs with Tom Lackowski, project manager; Rod Jedziniak, project design coordinator; and Tim Trout, project construction coordinator, all of FESS.

    The primary challenge in constructing the beamlines will be in accommodating fixed features and structures, both man-made and natural.

    “The locations of the g-2 and Mu2e buildings were fairly fixed because there are already utility corridors underground,” Convery said. “There are also wetlands that we are trying not to disturb.”

    Convery said that these physical constraints were important considerations in designing the experiments’ beamlines, since the space available to accomplish the necessary beam manipulations was limited.

    “It is not only the geometry of the beamlines that we have to conform to,” Lackowski said. “We also have to make sure the many services — the cable trays and the water services for cooling — are all coordinated.”

    Because the two muon experiments use the same beamlines at different energies, they cannot be run simultaneously.

    For both experiments, protons will proceed through the Linac, course through the Booster and then travel through the Recycler. A set of beamlines connects the Recycler to the Muon Campus. For the Muon g-2 experiment, the proton beam hits a target, converting the beam to a mixture of pions, protons and muons. The particles circle the Muon Delivery Ring several times, where protons are then removed and the remaining pions decay into muons. When the Muon g-2 experiment is taking data, the muon beam will continue to the experiment in the MC-1 Building.

    In contrast, for the Mu2e experiment, the protons bypass the target station and are transported to the Delivery Ring. The Mu2e protons also circle the Delivery Ring, then continue as an all-proton beam to the target in the Mu2e building area.

    Convery says work is also being done on other technical upgrades, such as installing magnets, along the beamline route.

    She expects the Muon g-2 experiment to begin in 2017, with Mu2e starting later, as scheduled.

    “Fermilab people have worked together for many years on various beamline projects,” Lackowski said. “We have had a very tight relationship with Mary and other colleagues, so we believe the Muon Campus tunnel project will go well.”

    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.

     
  • richardmitnick 4:54 pm on December 8, 2014 Permalink | Reply
    Tags: Accelerator Science, , ,   

    From LBL: “World Record for Compact Particle Accelerator” 

    Berkeley Logo

    Berkeley Lab

    December 8, 2014
    Kate Greene 510-486-4404

    Using one of the most powerful lasers in the world, researchers have accelerated subatomic particles to the highest energies ever recorded from a compact accelerator.

    l
    A 9 cm-long capillary discharge waveguide used in BELLA experiments to generate multi-GeV electron beams. The plasma plume has been made more prominent with the use of HDR photography. Credit: Roy Kaltschmidt

    The team, from the U.S. Department of Energy’s Lawrence Berkeley National Lab (Berkeley Lab), used a specialized petawatt laser and a charged-particle gas called plasma to get the particles up to speed. The setup is known as a laser-plasma accelerator, an emerging class of particle accelerators that physicists believe can shrink traditional, miles-long accelerators to machines that can fit on a table.

    The researchers sped up the particles—electrons in this case—inside a nine-centimeter long tube of plasma. The speed corresponded to an energy of 4.25 giga-electron volts. The acceleration over such a short distance corresponds to an energy gradient 1000 times greater than traditional particle accelerators and marks a world record energy for laser-plasma accelerators.

    “This result requires exquisite control over the laser and the plasma,” says Dr. Wim Leemans, director of the Accelerator Technology and Applied Physics Division at Berkeley Lab and lead author on the paper. The results appear in the most recent issue of Physical Review Letters.

    Traditional particle accelerators, like the Large Hadron Collider at CERN, which is 17 miles in circumference, speed up particles by modulating electric fields inside a metal cavity. It’s a technique that has a limit of about 100 mega-electron volts per meter before the metal breaks down.

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

    Laser-plasma accelerators take a completely different approach. In the case of this experiment, a pulse of laser light is injected into a short and thin straw-like tube that contains plasma. The laser creates a channel through the plasma as well as waves that trap free electrons and accelerate them to high energies. It’s similar to the way that a surfer gains speed when skimming down the face of a wave.

    The record-breaking energies were achieved with the help of BELLA (Berkeley Lab Laser Accelerator), one of the most powerful lasers in the world. BELLA, which produces a quadrillion watts of power (a petawatt), began operation just last year.

    LBL BellaBELLA at LBL

    “It is an extraordinary achievement for Dr. Leemans and his team to produce this record-breaking result in their first operational campaign with BELLA,” says Dr. James Symons, associate laboratory director for Physical Sciences at Berkeley Lab.

    In addition to packing a high-powered punch, BELLA is renowned for its precision and control. “We’re forcing this laser beam into a 500 micron hole about 14 meters away, “ Leemans says. “The BELLA laser beam has sufficiently high pointing stability to allow us to use it.” Moreover, Leemans says, the laser pulse, which fires once a second, is stable to within a fraction of a percent. “With a lot of lasers, this never could have happened,” he adds.

    cs
    Computer simulation of the plasma wakefield as it evolves over the length of the 9-cm long channel. Credit: Berkeley Lab

    At such high energies, the researchers needed to see how various parameters would affect the outcome. So they used computer simulations at the National Energy Research Scientific Computing Center (NERSC) to test the setup before ever turning on a laser. “Small changes in the setup give you big perturbations,” says Eric Esarey, senior science advisor for the Accelerator Technology and Applied Physics Division at Berkeley Lab, who leads the theory effort. “We’re homing in on the regions of operation and the best ways to control the accelerator.”

    In order to accelerate electrons to even higher energies—Leemans’ near-term goal is 10 giga-electron volts—the researchers will need to more precisely control the density of the plasma channel through which the laser light flows. In essence, the researchers need to create a tunnel for the light pulse that’s just the right shape to handle more-energetic electrons. Leemans says future work will demonstrate a new technique for plasma-channel shaping.

    Multi-GeV electron beams from capillary-discharge-guided subpetawatt laser pulses in the self-trapping regime by W. P. Leemans, A. J. Gonsalves, H.-S. Mao, et al. was published in Physical Review Letters on December 8, 2014.

    See the full article here.

    Please help promote STEM in your local schools.

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  • richardmitnick 6:49 pm on December 7, 2014 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From htxt.africa via FNAL: “Meet Claire Lee, a South African ATLAS physicist at CERN” 


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

    htxtdotafrica

    Anyone with even a passing interest in the sciences must have wondered what it’s like to work at the European Organisation for Nuclear Research, better known as CERN. Based in Switzerland, it’s one of the world’s largest and most respected centres for scientific research, birthplace of the worldwide web and home of the gigantic underground particle accelerator, the Large Hadron Collider (LHC).

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

    What wonders await those who join its ranks? What marvels must there be in the midst of such concentrated brain power?

    Since our chances of landing a job at CERN are probably limited to exciting opportunities in catering or sanitation, we figured it’s better to ask someone who does know. Someone like South African phyicist Claire Lee, who works right on ATLAS – one of the two elements of the LHC project that confirmed the existence of the Higgs boson in 2012.

    CERN ATLAS New
    ATLAS

    Lee has been involved with CERN since 2008 and has lived at the Swiss institute with her family for the past three and a half years. htxt.africa’s Tiana Cline sat down with Lee for a chat about all-things CERN, astrophysics and the elusive Higgs.

    How did you get interested in physics?

    Haha, this is a funny story. I’ve always loved science as long as I can remember (when I was very little I wanted to be an astronaut or an archaeologist), and have been fascinated with space since I could walk. But it really started in high school when I read the book Sphere by Michael Crichton. There was a character in the book who was an astrophysicist and I remember thinking to myself “Astrophysicist has to be about the coolest job title in the world, I want to be that!” So I set off to university with astrophysics as my final goal; however the astro-related projects that I ended up doing just didn’t seem to ever grab my interest. It was only in 2004, when for my Honours project I followed a basic version of what a friend was doing for his PhD in high energy nuclear physics, that I really started feeling the excitement.

    ac
    ATLAS Collaboration

    So science and physics were always a passion?

    In physics, High Energy Physics (HEP) is definitely my favourite, with a focus on Higgs and Beyond the Standard Model (BSM) physics. Our current theoretical knowledge is culminated in what is known as the Standard Model of Particle Physics, though we know that the theory is not complete (it doesn’t explain dark matter or dark energy, for example, nor the neutrino masses, and we have no idea how to incorporate gravity into the mix). So clearly there is lots of work still to do that will keep us hopefully busy with discoveries (or at least progress) for a while.

    In other fields, I do enjoy following the latest results in cosmology (such as the Planck vs BICEP2 saga, and AMS) and in particular where the fields of cosmology/astrophysics and particle physics overlap.

    And on a more personal note, neuroscience and the way the brain learns is fascinating too.

    Before jetting off to CERN, you studied in South Africa at both Wits and the University of Johannesburg as well as in Taiwan…

    I started off doing a BSc degree at Wits, I took Physics, Math, Applied Math and Chemistry in first year (2001). I hated Chemistry, so I dropped that first, took a second year Astronomy course, and ended up with Physics & Applied Math in 3rd year. I then did an Honours in Physics which was possibly one of the most fun years I’ve had in my life (we were a great class – 2004). At the end of that year I travelled to Virginia, USA for three weeks to work on an experiment at Jefferson Lab which became the subject of my MSc. I finally finished the MSc in 2009, also through Wits, and then moved to UJ where my supervisor had moved.

    As of 2007 South Africa wasn’t yet involved in the ATLAS experiment (though we had been working on ALICE, as well as ISOLDE and some of the smaller NA experiments for quite some time). But the annual South African Institute of Physics (SAIP) Conference we met Ketevi Assamagan, a US citizen originally from Togo, who was working at Brookhaven National Laboratory (BNL) on ATLAS. He had been invited to South Africa to speak at the conference – I think by Zeblon Vilakazi, member of the ALICE collaboration and (I think) director of iThemba LABS at the time. A group of us, especially my supervisor Prof Simon Connell and myself, were particularly interested in the type of physics ATLAS was doing, and a year later (2008) we flew to CERN to attend one of the ATLAS collaboration internal conferences, and meet with some of the heads of the experiment to discuss our involvement.

    The end of 2008 also saw the launch of the South Africa – CERN Programme which brought all the groups working on the various experiments together under one consortium.

    “Our current theoretical knowledge is culminated in what is known as the Standard Model of Particle Physics, though we know that the theory is not complete…” — Claire Lee, South African particle physicist

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

    ATLAS is an expensive experiment to keep running, and as such requires a financial commitment from its member institutions. There are yearly fees based on personnel (students are free), as well as a joining fee which equates to about R1M. The agreement was that we would have two years to account for the joining fee (from the DST), and BNL would cover our yearly fees in the meantime. In 2009 Prof Connell was at UJ, and Wits hired an ATLAS physicist Prof Trevor Vickey. Together they got their respective universities to commit to R250k each of the ATLAS joining fee, and the government to the other R500k, and in July 2010 the two universities were officially voted into the ATLAS collaboration as part of a single South African institute. (Since then UCT and then UKZN have joined the cluster.)

    I also lectured at UJ (first year calculus-based physics, extended programme) for two years from 2009-2011, and my son was born in May 2010.

    Thanks to popular TV shows like the Big Bang Theory, places like CERN and the idea of being a physicist has been somewhat romanticised. What is life at CERN really like?

    My best friend came to visit and described it as “Just like a huge university, with no undergrads” and that’s a pretty good explanation! There are so many facets to it, but for the most part you wouldn’t say you were at one of the world’s top scientific institutions just by walking around: most of the buildings were built to pretty utilitarian standards. We joke that all expense was spared above ground here, but it is part true as the most important part are the accelerators and detectors below ground. CERN itself employs less than 3 000 people – some scientists, but mostly staff in management, HR and engineering. There are about 10 000 people working on CERN projects in total, but most are attached to their own University or institute, and definitely not all at CERN at once!

    CERN has a large turnover of people, one of its missions is to train people in a worldwide environment and then let them take their experience back home, and so there is always a flux of especially young people moving in and out of the area (it gives you a whole new perspective on the concept of friends). A lot of people will move to CERN for a year or so of their PhD, especially at the start, to completely immerse themselves in the physics, and then move back to their home institute for the rest of their degree, just making occasional trips to CERN.

    It’s easy to just focus completely on the physics aspect, but of course there is a large social side too, and CERN has a number of clubs and societies for just about anything you can think of (sailing, dancing, karate, LGBT and so on). CERN also does a great deal of outreach – I have hosted a number of underground visits to ATLAS, and virtual visits to the control room, competed in, compared and judged the FameLab competition, as well as co-organised two standup comedy evenings!

    I think one of the things I really like about the CERN ethos in general is that it doesn’t matter who you are, what matters is what you are good at. And CERN has become pretty good at using the talents of their personnel to their best advantage (as long as you’re happy for them to be used, of course!).

    What has been the most interesting part about being at CERN since you moved to Switzerland at the end of June 2011?

    There have been so many interesting things – being on shift and looking after a part of the detector during the 2012 physics run was great, and the Higgs boson discovery and announcement was a huge highlight! But also the people – everyone I meet is pretty great in one way or another, and I have made some very close friends who are all amazing at what they do as well as in their extracurricular activities. It’s wonderful to be surrounded by so many exceptional people.

    Also, on a personal note, watching my son grow up in the French-speaking world has been amazing. He was just over a year old when we moved over, and at one and a half he started going to a French creche (my husband looked after him full-time for those first five months while I worked). He now speaks fluent French (WAY better than either of us) as well as English.

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    Lee hosting a “virtual visit” with Algeria from the ATLAS control room.

    A silly question – but what do you actually do on a day-to-day basis?

    My standard day is usually comprised of some mix of coding and attending meetings (either in person or remotely via Skype), interspersed with coffees and lunch. There are many different types of work one can do, since I am mostly on analysis this means coding, in C++ or Python, for example to select a particular subset of events that I am interested in from the full set of data. This usually takes a couple of iterations, where we slim down the dataset at each step and calculate extra quantities we may want to use for our selections.

    The amount of data we have is huge – petabytes of data per year stored around the world at various high performance computing centres and clusters. It’s impossible to have anything but the smallest subset available locally – hence the iterations – and so we use the LHC Computing Grid (a specialised worldwide computer network) to send our analysis code to where the data is, and the code runs at these different clusters worldwide (most often in a number of different places, for different datasets and depending on which clusters are the least busy at the time). At the ultimate or penultimate step our personalised datasets are usually small enough to put somewhere local (either on a laptop or university cluster) from which we can make nice-looking plots etc.

    Various meetings happen all day every day on ATLAS, though of course you only attend the ones relevant to the work you are doing as it would be impossible otherwise! Whether it’s an analysis- or performance-related meeting (analysis is, eg, a particular physics analysis, such as a Higgs measurement, while performance studies relate to the measurement and calibration of the physics objects – like electrons – that are used in the analyses) people will present their most recent work, and usually there will be some discussion on how to move forward.

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    View of the ATLAS cavern side A beginning of February 2008, before the lowering of the Muon Small Wheels.

    And on the ATLAS Experiment?

    The ATLAS experiment is one of the four large experiments at the LHC. It is also the biggest of the four detectors (in volume) and like CMS, is a general-purpose detector, designed to detect all particles from the high energy proton-proton collisions. This allows ATLAS to cover many different aspects of physics, from measurements of the Higgs boson to searches for new physics. The detector itself is built like a giant three-dimensional puzzle of different detector components, with each part measuring a different aspect of the final-state particles from the collisions as they move through the detector.

    To be able to do any analysis, after the data has been recorded the events have to be reconstructed, meaning that the signals from the different parts of the detector are combined and fitted into objects such as electrons, muons, jets etc. Analyses can then select events based on the objects they have in them – a Higgs boson decaying to four leptons, for example, would then select events containing electrons and/or muons.

    Other quantities based on these objects are also calculated, such as the missing transverse momentum, which is the vector sum of the energies of all the particles in the event, measured by the calorimeters (and comes about due to conservation of momentum). This is important for events where we have particles that we do not detect, such as neutrinos, and so the only way we know they are there is by noticing an imbalance in the total momentum (the neutrino would then be going in the other direction). A very large amount of missing momentum, by the way, could also be a signal for a supersymmetric particle, so this quantity is used in a number of analyses.

    I’ve done various things – I worked as an online expert for one of the ATLAS calorimeters, for example, making sure that it was running properly and able to take good data while the collisions were happening. This sometimes involved being called in the middle of the night to solve problems!

    But one of my main tasks, and what my thesis is on, has been developing a new and complimentary method of measuring the missing transverse momentum, only this time we use particle track momenta rather than calorimeter energy measurements. This method has proven to be very useful, especially when combining the result with the “traditional” measurement from the calorimeter, and is used in various Higgs analyses to help separate signal from background.

    We’ve heard that there are over 3 000 physicists working on ATLAS. Who are the other African scientists working at the institute? It must be interesting working with such a diverse group of people.

    Ketevi Assamagan (who is now a co-supervisor of mine), for example, was the first ATLAS physicist I ever met. My other supervisor (Rachid Mazini) works for Taiwan but he is originally from Morocco. And of course although the groups have grown in the past few years, the High Energy Physics community in South Africa is pretty small, and we all fall under the SA-CERN programme, so we know each other quite well.

    There are over 100 different nationalities represented on ATLAS, so you become quite culturally-aware, especially when it comes to being sensitive of others’ commitments around things like Thanksgiving, Ramadan, Christmas, etc, as well as personal issues like kids. I’ve found that people are in general pretty tolerant, and as long as your work is coming along well you are pretty free to work as you see fit.

    swh
    Several hundred of the 1 700 scientists contributing to the LHC accelerator and experiments gathered in CERN’s building 40.

    Back to South Africa – are you positive about the state of science/physics education here?

    Yes and no. I think universities are doing a good job, mostly, we do have some top quality researchers here in South Africa and are able to place well on the international scale. On the other hand, the quality of the schooling is going down terribly, and some of the students gaining university entrance nowadays and qualifying for these courses know extremely little. This only puts pressure on the universities, increasing lecturers’ loads, which is unfortunate.

    Science is tough generally, and the sort of high-pressure environment that ATLAS is even tougher, so you need to have some internal reason to continue doing what you do. Second, making sure you have really supportive people around you also is important, people who encourage you to succeed and are there for you when you need them. And finally, it’s about making contacts; attending meetings (in person if you can) and talking to people and presenting your work regularly, as well as more “fun” stuff like outreach, all helps to get people to know who you are and what you can do.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

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

     
  • richardmitnick 12:04 pm on December 4, 2014 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From FNAL- “Frontier Science Result: CDF Wading through the swamp to measure top quark mass” 


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

    Thursday, Dec. 4, 2014
    edited by Andy Beretvas

    Even after the discovery of the Higgs boson, the top quark is still a focus of attention because of its peculiar position of being the heaviest quark in the Standard Model and for its possible role in physics beyond the Standard Model.

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

    If the Standard Model is correct, the stability of the vacuum strongly depends on the mass of the Higgs boson and the top quark mass. In this context, scientists favor the scenario that the universe is in a metastable state. A precision measurement of the top quark mass helps to better determine the relative stability of that state in this scenario.

    At the Tevatron, top quarks were produced, mostly in pairs, only once in about 10 billion collisions. They decayed right away into a W boson and a b quark. In the most abundant and yet most challenging scenario, the final state contains six collimated sprays of particles, called jets, two of which likely originated from the b quarks, with peculiar, identifiable characteristics (allowing them to be “b-tagged”). This decay mode is usually called the all-hadronic channel, for which the signal is swamped by a background associated to the production of uninteresting multijet events, which were about a factor of 1,000 more abundant than the signal events.

    FNAL Tevatron
    Tevatron

    This new analysis uses the full CDF Run II data set.
The set contains nearly twice the number of top quark pairs as seen in our previous measurement. The analysis uses an improved simulation and relies on there being at least one b-tagged jet. An important part of the analysis is to minimize the uncertainty in our measurement of jet scale energies. Exploiting the expected behavior of top-antitop signal events, the huge background can be tamed through finely tuned requirements, yielding about 4,000 events, where about one event out of three is expected from the signal. The all-hadronic final state can then be fully reconstructed using the energies of the six jets, and the mass of the top quark can be derived comparing the data to simulations produced for different input values of the top quark mass (see the [below] figure).

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    The black dots plot the distribution of the reconstructed top mass for events containing one or more b-tags. The distribution is compared to the expected yield for background and signal events, normalized to the best fit.

    FNAL CDF
    CDF

    This procedure yields a value of 175.1 ± 1.2 (stat) ± 1.6 (sys) GeV/c2 for the top quark mass, with a 1 percent relative precision. This measurement complements the results obtained by CDF in other channels. Our measurement is consistent with the current world average (which includes our previous measurement in the all-hadronic channel), obtained from measurements by ATLAS, CDF, CMS and DZero. The top quark mass world average is 173.3 ± 0.8 GeV/c2.

    CERN ATLAS New
    ATLAS

    CERN CMS New
    CMS

    FNAL DZero
    DZero

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    Fermilab Campus

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

     
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