Tagged: LHC Toggle Comment Threads | Keyboard Shortcuts

  • 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:

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 10:29 am on July 31, 2013 Permalink | Reply
    Tags: , , , , , LHC, ,   

    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:

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • 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.

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 6:26 am on April 9, 2013 Permalink | Reply
    Tags: , , , LHC, ,   

    From CERN: “The LHC at level best” 

    CERN New Masthead

    April 9 2013
    Katarina Anthony

    “The Large Hadron Collider (LHC) tunnel is renowned for its geological stability: set between layers of sandstone and molasse, it has allowed the world’s largest accelerators to run to sub-millimetre precision. But even the most stable of tunnels can be affected by geological events. To ensure the precise alignment of the LHC, the CERN survey team performs regular measurements of the vertical position of the magnets (a process known as “levelling”).

    level
    CERN surveyors take levelling measurements of the LHC magnets (Image: CERN)

    The team has taken measurements of the LHC before its temperature reached 100 K, beyond which there may be some mechanical movements. As no data could be gathered while the machine was in operation, these measurements will provide the clearest picture yet of the accelerator’s position at the end of its run. The team used a so-called “fast levelling” technique, which involves measuring every second magnet in order to complete the survey as quickly as possible and to reduce the influence of the environmental conditions that could affect the observations made with an optical level. Technicians were able not only to measure the height of the magnets but also to make immediate height comparisons with the previous magnets. No magnet realignments were carried out at this stage.

    ‘By comparing these measurements with the base measurements taken during the 2008-2009 shutdown, we will soon have an accurate picture of how ground disturbances may have affected the machine,’ says Dominique Missiaen, leader of the Beams department section responsible for large-scale metrology. ‘This comparison will also help us predict possible future deviations and deterioration of the relative positions between magnets.’”

    See the full article here.

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 8:50 am on March 27, 2013 Permalink | Reply
    Tags: , , , , LHC, ,   

    From CERN: “CMS open for business” 

    CERN New Masthead

    March 27, 2013
    Cian O’Luanaigh

    As CERN goes into its first long shutdown, it’s time open up the CMS detector and get inside for maintenance and repairs. Engineers and technicians started opening the CMS detector on 7 March, but moving the parts of this 14,000-tonne behemoth is no easy feat.

    cms
    The open side of the CMS detector, looking upwards from the cavern floor (Image: Michael Hoch/CMS)

    CMS has a barrel section made of five rings, with two endcaps each comprising three discs and, outside those discs, two 250-tonne forward hadron calorimeters (HF) [see diagram]. To open CMS, the HFs, which surround the beam pipe, are opened and lowered to the cavern floor, where they are floated on air pads into storage alcoves. Then the endcap discs are moved away from the barrel, starting with one end and then going to the other.

    ‘It took a couple of weeks of work to move the forward calorimeters and the first three discs apart,’ says detector physicist David Barney of CMS. ‘Then we went to the other end and started to move the other three discs.’

    Barney has worked on one part of CMS, the electromagnetic calorimeter (ECAL) for nearly 20 years. The ECAL is mainly made of lead tungstate crystals that detect photons and electrons. But in the endcaps, an extra detector called the preshower sits in front of the crystals. The preshower is an array of silicon sensors that measure precisely the positions of incident high-energy electrons and photons.”

    See the full article here.

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 8:46 am on March 20, 2013 Permalink | Reply
    Tags: , , , , , LHC   

    From CERN ALICE: "How ALICE was born’" 

    CERN New Masthead

    20 March 2013
    Hans H.Gutbrod

    Alice Icon New

    “In 1982 a MoU was signed by GSI, Darmstadt, CERN and LBL Berkeley to get heavy ions to CERN: GSI promised to bring an ECR-ion source and LBL a RFQ Linac to the CERN site. Rudolf Bock(GSI), Herrmann Grunder (LBL) and Reinhard Stock (Uni Marburg) and others proposed to have heavy ions in the CERN PS. Robert Klapisch, then research director of CERN, found SPS more adequate and this lead to heavy ion physic[s] with Oxygen beams in 1986, sulphur beams in 1987 and lead beams in 1994.
    sps
    The Super Proton Synchrotron

    In 1983 at the relativistic heavy ion meeting at Brookhaven, I discussed with Carlo Rubbia topics of the future heavy ion collider at BNL, later called RHIC, when he told me: ‘You will get your collider at CERN, with enough energy for your physics case’

    A few years later, a proposal for a heavy-ion programme was submitted in the LHC project . Rubia, kept his promise and among many things he insisted on a two-in-one magnet solution for the LHC instead of a pp_bar mode with only one vacuum chamber (what’s the benefits of this architecture? One vacuum chamber and one magnet is only good for ppbar, an option several persons preferred since it was also cheaper ).

    From 1991 on, a group of about 20 persons met at CERN regularly to work on a proposal for a dedicated heavy ion experiment at the LHC. In parallel we had to build and run our lead beam experiments at the SPS. ”

    And, so it goes in HEP. Read the full article here.

    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


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 12:27 pm on February 14, 2013 Permalink | Reply
    Tags: , , , , , LHC, , ,   

    From Richard Ruiz at Quantum Diaries: “Using Physics to Find More Physics” 

    trr
    Richard Ruiz

    A maxim in particle physics says to use physics to find more physics!

    I forget from where or whom I first heard this saying but the idea goes something like this: When a new particle is discovered, in principle, our knowledge of the particle only consists of what we have directly measured and what the theory that lead us to its discovery tells us. The theory, of course, is most likely incorrect but that is the point. As far as we know, any newly discovered particle might have some hereto unknown quantum number. But if this is the case, then by scrutinizing a new particle we might get lucky, very luck and discover something completely unexpected. One perfect example comes from neutrino physics. After finally discovering them, physicists learned eventually how to make beams of neutrinos only to find out (1) that there are several types of neutrinos and (2) they have mass. Another example involves the W boson and brief history of modern particle colliders.

    The purpose of particle colliders like the Super Proton Synchrotron (SPS), the Large Electron-Positron collider (LEP), the Tevatron, or the Large Hadron Collider (LHC) is to test physical theories in order to ultimately figure out what works and doesn’t work.

    This is how research in high energy physics progresses: discover something new, turning it around, and throwing it back at itself. You can be certain that there is already research into scattering Higgs bosons and how this next iteration of collisions could be excellent tests of theories like technicolor, extra dimensions, or the existence of additional vector bosons. Until next time! Happy Colliding.”

    This post barely scratches at all of the information in Dr. Ruiz’ article. See the full article here.

    Participants in Quantum Diaries:

    Fermilab

    Triumf

    US/LHC Blog

    CERN

    Brookhaven Lab

    KEK


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 11:27 pm on February 5, 2013 Permalink | Reply
    Tags: , , , , LHC, ,   

    From Symmetry: “What’s next for the Large Hadron Collider?” 

    February 04, 2013
    Ashley WennersHerron and Kathryn Jepsen

    Experiments at the Large Hadron Collider made a major discovery, but the world’s highest-energy particle accelerator is just getting started.

    CERN LHC New

    The Large Hadron Collider, the largest particle accelerator in the world, started colliding particles more than three years ago. Since then, scientists have published more than 700 papers detailing the knowledge they have gained at the cutting edge of particle physics.

    Undisputedly, the most famous insight so far has been the discovery of what could be the long-sought Higgs boson. This particle is thought to arise from the fluctuation of the invisible ‘Higgs field’ that pervades the universe, imparting mass to particles that interact with it. Without the Higgs field, our world would be a much different place.

    Even during the excitement of that discovery, thousands of scientists—more than 1800 of whom are based in the United States—continued the important work of analyzing the continuing flood of new data pouring out of their detectors.

    There is still much to learn about the new, Higgs-like particle. And there is still much more territory to cover in the search for new physics. The LHC will expand its reach dramatically when scientists crank its energy from 4 trillion to 6.5 trillion electronvolts in 2015.

    Since the LHC turned on, the ATLAS, CMS, LHCb and ALICE experiments—along with the smaller experiments TOTEM and LHCf—have discovered a total of three particles…Searching for new particles is just one continuing function of the LHC experiments. Now that scientists have uncovered new particles, they have another focus—finding out more about them.

    The new Higgs-like particle, for example, seems to fulfill at least the minimum role of the Higgs boson, as it interacts with particles in more or less the expected way. But observations of the new particle’s properties—its spin, parity and detailed interactions—could show it to be a different kind of Higgs than the one predicted by the Standard Model, the theory used to explain the makeup and interaction of particles and forces in our universe.

    Standard Model
    Standard Model with “Higgs”

    ‘We could be looking at a new framework,’ says Joao Varela, a physicist with the Portuguese institute LIP and CMS deputy spokesperson. ‘It may not be the Standard Model or even supersymmetry. It might be something else entirely.’

    Conversely, if the Higgs turns out to be the particle scientists expected to find, physicists will have finally discovered every piece predicted in the Standard Model.

    Yet even with a Standard Model Higgs, questions will remain in particle physics theory.”

    There is a lot more to this very thorough article. Please, take a look here.

    Symmetry is a joint Fermilab/SLAC publication.


    ScienceSprings is powered by MAINGEAR computers

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: