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  • richardmitnick 5:55 pm on April 17, 2014 Permalink | Reply
    Tags: , , , , LHC, ,   

    Before you watch Particle Fever 

    I have put this video up before, but there is no time like the present. Released to theaters is Particle Fever, the story of the hunt for the Higgs boson. This movie will go to DVD pertty quickly, maybe to Netflix streaming, maybe to YouTube. Before you see it, be sure to see The Big Bang Machine with Dr. Sir Brian Cox, OBE

    You should also see The Atom Smashers, about the hunt at Fermilab. However, I cannot find a copy which WordPress will allow

     
  • richardmitnick 4:49 pm on December 3, 2013 Permalink | Reply
    Tags: , , , LHC, ,   

    From CERN: “CMS presents evidence for Higgs decays to fermions” 

    CERN New Masthead

    Achintya Rao
    3 Dec 2013

    At a seminar at CERN this morning, the CMS collaboration presented several measurements of the properties of the Higgs boson. CMS showed strong evidence for the decay of Higgs bosons into fermions, corroborating CMS results shown earlier this year. CMS physicists have now measured the decay of the Higgs to pairs of bottom (b) quarks and pairs of tau leptons, with a combined significance of 4 sigma on the 5-point scale that particle physicists use to measure the certainty of a result. This significance means that the probability of a false positive is estimated to be only about one in 16,000.

    The decay to fermions is an important confirmation that the particle discovered in July 2012, with a mass of around 125 GeV, behaves like the Standard Model Higgs boson. The Higgs decays into pairs of lighter particles almost immediately after it is produced in proton collisions in the LHC. In general, particles can decay into various combinations of daughter particles. The Standard Model gives precise predictions for what the decay products are and how often they should occur.

    sm
    Standard Model of Particle Physics

    So far, the Higgs boson has been observed decaying into three types of gauge bosons: the Z, the W and the photon. The Standard Model also predicts decays to fermions – namely quarks and leptons, the fundamental particles of matter. The fermionic decays into b quarks and tau leptons are particularly strong: they are the heaviest fermions that a Higgs with a mass of around 125 GeV would decay into and are consequently the most likely fermionic decays to occur.

    Using data collected at a collision energy of 7 TeV in 2011 and at 8 TeV in 2012, CMS has now completed refined searches for tau decays with several improvements over previous analyses and found an excess in this channel corresponding to significance of 3.4 sigma. Together with earlier CMS searches for b decays that revealed a 2.1 sigma excess, excesses in the two channels have a combined significance of 4 sigma, indicating strong evidence for the Higgs decaying to fermions.

    See the full article here.

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  • richardmitnick 4:58 am on October 10, 2013 Permalink | Reply
    Tags: , , , LHC   

    From CERN: “Watch CERN physicists react to Nobel announcement” 

    CERN New Masthead

    Cameras were rolling in CERN’s building 40 on Tuesday when members of the ATLAS and CMS collaborations heard the news from the Swedish Academy of Sciences that François Englert and Peter W. Higgs had received the 2013 Nobel prize in physics. Watch their reaction in the video above.

    The Nobel prize was awarded to Englert and Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.” The ATLAS and CMS collaborations announced their discovery of the particle at CERN on 4 July 2012.

    As the news came through from Stockholm, CERN physicists burst into applause, and CERN Director-General Rolf Heuer gave a spontaneous speech congratulating the theoretical physicists for the award and the experimental physicists at CERN for their discovery.

    The ATLAS and CMS collaborations each involves more than 3000 people from all around the world. They have constructed sophisticated instruments – particle detectors – to study proton collisions at CERN’s Large Hadron Collider (LHC), itself a highly complex instrument involving many people and institutes in its construction.

    See the full article here.

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  • richardmitnick 11:53 am on September 13, 2013 Permalink | Reply
    Tags: , , , , LHC, ,   

    From Symmetry: “The hunt for microscopic black holes” 

    Finding micro black holes at the LHC would alert scientists to the existence of extra dimensions, which might explain why gravity seems so weak.

    September 13, 2013
    Kelly Izlar

    The energy required for a black hole like the one at the center of our galaxy to form—the amount contained in a dying, super-massive star collapsing in on itself—is many times higher than what we can achieve in our earthly laboratories.

    However, if certain theories are correct about the nature of gravity, there may be a way for physicists to create a very different type of black hole—one so small and fleeting that its presence could only be inferred from its effect on subatomic particles in a particle detector. And this process may be within reach of the Large Hadron Collider.

    CERN LHC Map

    According to some theories, there are more than just three dimensions of space. The existence of extra dimensions would offer an answer to one of the most prominent mysteries in physics today: why gravity is so weak when the other fundamental forces are so strong. The more dimensions there are, the more gravity will dilute over increasing distances. The force will weaken as it scatters farther afield, but it will be surprisingly strong at short distances.

    If there are 10 dimensions, for example, then the gravitational force must propagate through several more spatial dimensions than we can detect; it seems weak to us only because most of it is lost in the unseen dimensions.

    Physicists know that it should take a certain amount of energy—more than the LHC could ever conjure—to make a microscopic black hole. But if gravity is stronger than we think, then the threshold of energy needed could be within range of both the LHC and cosmic-ray collisions with Earth’s atmosphere, says theoretical physicist Steve Giddings from the University of California, Santa Barbara.

    “The great thing about microscopic black holes and extra dimensions is that there are many ways to look for them,” says Rutgers University scientist John Paul Chou, who serves as co-convener of the exotica physics group at the CMS experiment at the LHC. “But the LHC is the cleanest, most obvious way to create and find them.”

    CERN CMS New
    CMS

    When two particles hit dead-on at close to light speed, a small amount of energy greatly concentrates into a tiny space. If extra dimensions exist, the collision could reveal gravity’s hidden strength; the energy and density could be high enough to fuse into a microscopic black hole.

    A micro black hole would be too small and short-lived to have much effect on its surroundings. Scientists’ only clue would be a burst of extra particles (depicted in the event display on the right side of the mural pictured above). But its effect on our understanding of nature at the quantum level would be enormous. If physicists produced microscopic black holes at the LHC, they would have proof that there are more than three dimensions of space.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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  • richardmitnick 7:20 am on August 10, 2013 Permalink | Reply
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    From CERN: “The amazing world of smashed protons and lead ions” 

    CERN New Masthead

    In the CERN Bulletin
    Issue No. 33-35/2013 – Monday 12 August 2013
    Antonella Del Rosso

    alice

    “When a single proton (p) is smashed against a lead ion (Pb), unexpected events may occur: in the most violent p-Pb collisions, correlations of particles exhibit similar features as in lead-lead collisions where quark-gluon plasma is formed. This and other amazing results were presented by the ALICE experiment at the SQM2013 conference held in Birmingham from 21 to 27 July.

    event
    Event display from the proton-lead run, in January 2013. This event was generated by the High Level Trigger (HLT) of the ALICE experiment.

    Jet quenching is one of the most powerful signatures of quark-gluon plasma (QGP) formed in high-energy lead-lead collisions. QGP is expected to exist only in specific conditions involving extremely hot temperatures and a very high particle concentration. These conditions are not expected to apply in the case of less ‘dense’ particle collisions such as proton-lead collisions. ‘When we observe the results of these collisions in ALICE, we do not see a strong particle-jet suppression; however, when studying the most violent p-Pb collisions we observe signatures in particle production characteristic of a hydrodynamic nature,’ explains Mateusz Ploskon from the ALICE collaboration. ‘Indeed, some of the properties of the correlations of particles produced in proton-lead collisions resemble those associated with the formation of QGP in lead-lead collisions.’

    More data is needed to resolve the conundrum but in the meantime the physics community is excited as the phenomena observed in proton-lead collisions could have strong implications for our understanding of the QCD – the theory that describes the interactions of strongly interacting subatomic particles. ‘The p-lead data already provide an extremely useful baseline for the collisions of heavy ions; however, we need more time and more data to understand the intriguing observations from proton-lead collisions – it remains to be seen whether we learn something new about hadronic and nuclear collisions at high energies, and whether these observations have any unexpected implications for our understanding of QGP based on lead-lead collisions,’ says Mateusz.”

    See the full article here.

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  • richardmitnick 7:28 am on August 9, 2013 Permalink | Reply
    Tags: , , , , LHC   

    From CERN: “Tracking new physics—horse or zebra?” 

    CERN New Masthead

    9 Aug 2013
    Ashley Jeanne Wennersherron

    If you hear hoof beats, common sense says the cause is more than likely a horse. Yet, the possibility still exists that you’re actually hearing a zebra. Physicists at LHCb are applying that same logic to an unusual finding in a recent analysis of the B meson.

    lhcb
    A view of the LHCb detector. (Image: Maximilien Brice/CERN)

    Around one in every million B mesons decays into an excited kaon and two muons. The decay can occur in several different ways, so physicists classify them in what they call bins. The Standard Model predicts precisely the probability of the angles of these particle decays in each bin. The experiment can measure this probability, so it is an observable. Any difference between the measured observable and prediction could indicate new physics.

    Nicola Serra of LHCb, one of the analysts of the B meson decay data from 2011, and his colleagues found such a difference.

    “Most of the observables we measured in this analysis were close to Standard Model expectations, but a particular observable showed a sizable discrepancy,” he says.

    On the ‘sigma’ scale that physicists use to describe the certainty of a result, Serra’s discrepancy between the expected and the measured result scored 3.7 sigma – there could be evidence for new physics but they need more data to confirm it. When they considered the probability of seeing that particular deviation with all of the data from the entire analysis, the sigma level dropped to 2.8 sigma, translating to a half a percent chance that the discrepancy is caused by statistical fluctuation. (The gold standard for a discovery is 5 sigma.)

    A team of theorists then looked at the same decay and included more observables than the LHCb group did. They found, with this aggregation of many measurements, a consistent pattern of deviations that boosted the sigma to 4.5. That’s almost to the level of discovery, but within parameters that measure the presence of possible new physics. These parameters are more inclusive than those the LHCb team used.

    ‘The theoretical interpretation is very interesting; that can’t be denied,’ says Serra. ‘As an experimentalist, I have to focus on the data itself instead of the interpretation. If we see something that differs from the prediction, it’s crucial to understand if the pattern is real or not.’

    If there’s a deviation from the prediction, experimentalists try to understand if something is wrong with the data. Only once all of the machine systematics and statistics are checked and double-checked can they say, with certainty, that there is a true discrepancy.

    ‘The experimental paper only shows the data. The theory paper is the one that gives the interpretation. Both are pieces of a puzzle and they fit together nicely,’ says Joaquim Matias, a theorist from Autonomous University of Barcelona and one of the paper’s authors. ‘The experimentalists found deviations and the theorists showed that they can be explained within a consistent picture for the first time.’”

    See the full article here.

    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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  • richardmitnick 10:29 am on July 31, 2013 Permalink | Reply
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    From CERN: “ALICE through a gamma-ray looking glass” 

    CERN New Masthead

    31 July 2013
    Christine Sutton

    “The ALICE experiment at CERN specializes in heavy-ion collisions at the LHC, which can produce thousands of particles. In analysing this maelstrom, the researchers need to know exactly how material is distributed in the detector – and it turns out that the LHC’s simpler proton–proton collisions can help.

    layers
    A gamma-ray view of the layers of the ALICE detector. (Image: ALICE)

    Gamma-rays produced in the proton–proton collisions, mainly from the decays of neutral pions, convert into pairs of electrons and positrons as they fly through matter in the detector. The origin of these pairs can be accurately detected, providing a precise 3D image that includes even the inaccessible innermost parts of the experiment. The process is almost exactly the same as in 1895 when Wilhelm Röntgen produced an X-ray image of his wife’s hand – the inner parts of the body could be seen for the first time without surgery. The main difference lies in the energy of the radiation – ten times greater for the gamma rays in ALICE than for Röntgen’s X-rays. Importantly for the ALICE experiment, it allows the team to check crucial simulations.”

    See the full article here.

    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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    CERN ATLAS New

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    CERN ALICE New

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  • richardmitnick 4:54 pm on May 15, 2013 Permalink | Reply
    Tags: , , LHC, ,   

    From Symmetry: “What’s the next step in particle colliders” 

    “Already celebrated for bringing the world news of the Higgs boson, the Large Hadron Collider is only beginning its long journey of discoveries. Yet scientists are already planning the next big machine, the International Linear Collider [read Linear Collider, from the linear Collider Collaboaration], to study the LHC’s discoveries in more detail.

    So what’s the difference between the LHC and the proposed ILC? Why do we need both?

    LHC particles
    LHC

    lc
    Linear Collider.

    For one thing, the ILC would accelerate particles along a straight line some 30 kilometers long while the LHC accelerates them along a circular path 27 kilometers in circumference. But that just skims the surface of their differences.

    The two types of machine provide very different types of information because they collide different kinds of particles. The LHC collides protons, which themselves are made up of quarks and gluons. The ILC, in contrast, would collide electrons and positrons, point-like particles that have no known internal structure. Proton collisions are messy, allowing scientists to discover new particles and new processes, while linear-collider experiments are cleaner, allow scientists to explore these new particles and new processes without the complicated debris present at the LHC.

    Not clear? Maybe this image helps. The protons in the LHC aren’t just single particles; they are each made of a list of ingredients (up quarks, a down quark and gluons)…That’s why the LHC produces the mind-boggling number of collisions that it does.

    See the full scintillating article here.

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 9:18 am on April 17, 2013 Permalink | Reply
    Tags: , , , LHC, ,   

    From Symmetry: “LHC passes ‘ping-pong ball’ test” 

    Physicists sent an ultra-clean, miniature ping-pong ball through part of the Large Hadron Collider beam pipe to test for hidden defects.

    April 16, 2013
    Ashley WennersHerron

    “Sometimes the best solutions in high-energy physics research are surprisingly low-tech.

    test

    Physicists sent a carefully sterilized, slightly-smaller-than-regulation ping-pong ball through a 2-mile section of the Large Hadron Collider today. They were searching for possible defects in the connections between magnets that can arise as they change temperature.

    The so-called radio-frequency ball, first developed in 2007, carried a small transmitter that allowed scientists to track its progress. It moved through simple suction, pinging every third of a mile.

    ‘The beam pipes are fragile,’ says Vincent Baglin, the leader of the LHC beam vacuum section at CERN. ‘We always have to check and crosscheck to minimize any problems. This is a simple test that can prevent complicated issues.’”

    See the full article here.

    Also, see this article from CERN.

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 5:17 pm on April 13, 2013 Permalink | Reply
    Tags: , , , LHC, ,   

    From CERN: “Opening the LHC – in pictures” Don’t Miss this one. 

    CERN New Masthead

    If you want to really see where your tax money is going, do not miss this article from CERN

    12 Apr 2013.
    Cian O’Luanaigh

    inside
    This week technicians opened up the first interconnections between magnets on the Large Hadron Collider (LHC) to work on the accelerator components inside. Above, a technician prizes the thermal insulation plates from an interconnection between LHC magnets. Note the bicycles, which workers use to get around the LHC tunnel.

    All images by Maximilien Brice for CERN.

    There are two more terrific shots. Take a peak. The article is here.

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