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  • richardmitnick 5:11 pm on December 22, 2015 Permalink | Reply
    Tags: , , CERN LHC, Fabiola Gianotti, , ,   

    From Nature: “CERN’s next director-general on the LHC and her hopes for international particle physics” 

    Nature Mag
    Nature

    22 December 2015
    Elizabeth Gibney

    Fabiola Gianotti talks to Nature ahead of taking the helm at Europe’s particle-physics laboratory on 1 January.

    1
    Fabiola Gianotti is the incoming director-general of CERN. Maximilien Brice/CERN

    Fabiola Gianotti, the Italian physicist who announced the discovery of the Higgs boson in 2012, will from 1 January take charge at CERN, the laboratory near Geneva, Switzerland, where the particle was found.

    Gianotti spoke to Nature ahead of taking up the post, to discuss hints of new physics at the upgraded Large Hadron Collider (LHC), China’s planned accelerators and CERN’s worldwide ambitions — as well as how to deal with egos.

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

    How excited should we be about the latest LHC results, which already hint at signals that could turn out to be due to new physics phenomena?

    At the moment, experiments are seeing some fluctuations and hints, which, if they are due to signals from new physics, will next year consolidate with the huge amount of data the LHC will deliver. On the other hand, if they are just fluctuations, they will disappear. We have to be patient. In addition to looking for new physics, we are going to study the Higgs boson with very high precision.

    Will any of the hints that we’ve already seen be directing the physicists’ searches?

    I don’t think that the direction of exploration is being guided by the hints people see here and there. The correct approach is to be totally open and not be driven by our prejudices, because we don’t know where new physics is, or how it will look.

    Following the LHC’s energy upgrade, data collection in the 2015 run has been slower than hoped. How would you characterize it so far?

    Run 2 has been extremely successful. We have recorded about 4 inverse femtobarns of data [roughly equivalent to 400 trillion proton–proton collisions]. The initial goal was between 8 and 10 femtobarns, so it’s less. However, a huge number of challenges have been addressed and solved. So for me, this is more important than accumulating collisions. We could have accumulated more, but only by not addressing the challenges that will allow us to make a big jump in terms of intensity of the beams next year.

    In 2015, one LHC paper had more than 5,000 authors. There must be some people on such experiments who want more credit for their efforts.
    How do you deal with the clash of egos?

    I think the collaborations accept very well this idea that everybody signs the paper, and I am also a strong supporter of that. The reason is simple: you can be the guy who has a good idea to do a very cute analysis, so get very nice results. But you would not have been able to do the analysis if many other people had not built the detectors that gave you the data. None of these experiments is a one-man show, they are the work of thousands of people who have all contributed in their domain and all equally deserve to sign the paper.

    I hope that universities, advancement committees and boards that hire people understand that just because there are many authors, that does not mean the individual did not make an important contribution.

    CERN is currently at the heart of international particle physics, but China is designing a future collider that could succeed the LHC after 2035. Do you think that China could become the world’s centre for particle physics in the 2040s?

    At the moment there are many conceptual design studies for future big accelerators around the world. Of course conceptual studies are important, but there is a big step between studies and future reality. I think it is very good that all regions in the world show an interest and commitment to thinking about the future of particle physics. It’s a very good sign of a healthy discipline.

    Is there a chance that China might become a CERN member?

    Before becoming a full member, you become an associate member, and associate membership is something that can be conceived [for China]. So we will see in the coming years if this can become a reality. It’s an interesting option to explore.

    Do you plan to encourage more countries to become CERN members?

    Of course. A lot has been done since 2010 to enlarge CERN membership, in terms of associate members in particular, but also [full] members: we got Israel, for instance, and soon we will get Romania. I will continue along this direction.

    Some people think that future governments will be unwilling to fund larger and more expensive facilities. Do you think a collider bigger than the LHC will ever be built? And will it depend on the LHC finding something new?

    The outstanding questions in physics are important and complex and difficult, and they require the deployment of all the approaches the discipline has developed, from high-energy colliders to precision experiments and cosmic surveys. High-energy accelerators have been our most powerful tools of exploration in particle physics, so we cannot abandon them. What we have to do is push the research and development in accelerator technology, so that we will be able to reach higher energy with compact accelerators.

    Nature doi:10.1038/nature.2015.19040

    See the full article here .

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 2:19 pm on December 18, 2015 Permalink | Reply
    Tags: , , CERN LHC, , , , ,   

    From Symmetry: “CERN and US increase cooperation” 

    Symmetry

    12/18/15
    Sarah Charley

    1
    Eric Bridiers, US Mission

    The United States and the European physics laboratory have formally agreed to partner on continued LHC research, upcoming neutrino research and a future collider.

    Today in a ceremony at CERN, US Ambassador to the United Nations Pamela Hamamoto and CERN Director-General Rolf Heuer signed five formal agreements that will serve as the framework for future US-CERN collaboration.

    These protocols augment the US-CERN cooperation agreement signed in May 2015 in a White House ceremony and confirm the United States’ continued commitment to research at the Large Hadron Collider.

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

    They also officially expand the US-CERN partnership to include work on a US-based neutrino research program and on the study of a future circular collider at CERN.

    “This is truly a good day for the relationship between CERN and the United States,” says Hamamoto, US permanent representative to the United Nations in Geneva. “By working together across borders and cultures, we challenge our knowledge and push back the frontiers of the unknown.”

    The partnership between the United States and CERN dates back to the 1950s, when American scientist Isidor Rabi served as one of CERN’s founding members.

    “Today’s agreements herald a new era in CERN-US collaboration in particle physics,” Heuer says. “They confirm the US commitment to the LHC project, and for the first time, they set down in black and white European participation through CERN in pioneering neutrino research in the US. They are a significant step towards a fully connected trans-Atlantic research program.”

    Today, the United States is the most represented nation in both the ATLAS and CMS collaborations at the LHC.

    CERN ATLAS New
    ATLAS

    CMS Use this one
    CMS

    Its contributions are sponsored through the US Department of Energy’s Office of Science and the National Science Foundation.

    According to the new protocols, the United States will continue to support the LHC program through participation in the ATLAS, CMS and ALICE experiments.

    CERN ALICE New
    ALICE

    The LHC Accelerator Research Program, an R&D partnership between five US national laboratories, plans to develop powerful new magnets and accelerating cavities for an upgrade to the accelerator called the High-Luminosity LHC, scheduled to begin at the end of this decade.

    In addition, a joint neutrino-research protocol will enable a new type of reciprocal relationship to blossom between CERN and the US.

    “The CERN neutrino platform is an important development for CERN,” says Marzio Nessi, its coordinator. “It embodies CERN’s undertaking to foster and contribute to fundamental research in neutrino physics at particle accelerators worldwide, notably in the US.”

    The agreement will enable scientists and engineers working at CERN to participate in the design and development of technology for the Deep Underground Neutrino Experiment, a Fermilab-hosted experiment that will explore the mystery of neutrino oscillations and neutrino mass.

    FNAL Dune & LBNF
    DUNE

    For the first time, CERN will serve as a platform for scientists participating in a major research program hosted on another continent. CERN will serve as a European base for scientists working the DUNE experiment and on short-baseline neutrino research projects also hosted by the United States.

    Finally, the protocols pave the way beyond the LHC research program. The United States and CERN will collaborate on physics and technology studies aimed at the development of a proposed new circular accelerator, with the aim of reaching seven times higher energies than the LHC.

    The protocols take effect immediately and will be renewed automatically on a five-year basis.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 5:17 pm on December 9, 2015 Permalink | Reply
    Tags: , , CERN LHC,   

    From Symmetry: “Save the particles” 

    Symmetry

    12/09/15
    Sarah Charley

    To learn more about the particles they collide, physicists turn their attention to a less destructive type of collision in the LHC.

    1
    CMS. Maximilien Brice, CERN

    Every second, the Large Hadron Collider generates millions of particle collisions. Scientists watching these interactions usually look out for only the most spectacular ones.

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

    But recently they’ve also taken an interest in some gentler moments, during which the accelerated particles interact with photons, quanta of light.

    When charged particles—like the protons the LHC usually collides or the lead ions it is colliding right now—are forced around bends in an accelerator, they lose energy in the form of light radiation.

    Originally, physicists perceived this photon leak as a nuisance. But today, laboratories around the world specifically build accelerators to produce it. They can use this high-energy light to take high-speed images of materials and processes in the tiniest detail.

    Scientists are now using the LHC as a kind of light source to figure out what’s going on inside the protons and ions they collide.

    The LHC’s accelerated particles are chock-full of energy. When protons collide—or, more specifically, when the quarks and gluons that make up protons interact—their energy is converted into mass with manifests as other particles, such as Higgs bosons.

    Those particles decay back into energy as they sail through particle detectors set up around the collision points, leaving their signatures behind. Physicists usually study these particles, the ones created in collisions.

    In proton-photon collisions, however, they can study the protons themselves. That’s because photons can traverse a particle’s core without rupturing its structure. They pass harmlessly through the proton, creating new particles along the way.

    “When a high-energy light wave hits a proton, it produces particles—all kinds of particles—without breaking the proton,” says Daniel Tapia Takaki, an assistant professor at the University of Kansas who is a part of the CMS collaboration. “These particles are recorded by our detector and allow us to reconstruct an unprecedentedly high-quality picture of what’s inside.”

    Tapia Takaki is interested in using these photon-induced interactions to study the density of gluons inside high-energy protons and nuclei.

    As a proton is accelerated to close to the speed of light, its gluons swell and eventually split—like cells dividing in an embryo. Scientists want to know: Just how packed are gluons inside these protons? And what can that tell us about what happens when they collide?

    The Standard Model—a well-vetted model that predicts the properties of subatomic particles—predicts that the density of gluons inside a proton is directly related to the likelihood a proton will spit out a pair of charm quarks in the form of a J/psi particle during a proton-photon interaction.

    3
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    “So by measuring the J/psi’s production rate very precisely, we can automatically have access to the density of gluons,” Tapia Takaki says.

    Prior to joining the CMS experiment, Tapia Takaki worked with colleagues on the ALICE experiment to conduct a similar study of photon-lead interactions.

    AliceDetectorLarge
    ALICE

    Tapia Takaki plans to study the lead ions currently being collided in the LHC in more detail with his current team.

    The trickiest part of these studies isn’t applying the equation, but identifying the collisions, Tapia Takaki says.

    To identify subtle proton-photon and photon-lead collisions, Tapia Takaki and his colleagues must carefully program their experiments to cherry-pick and record events in which there’s no evidence of protons colliding—yet there is still evidence of the production of low-energy particles.

    “It’s challenging because the interactions of light with protons or lead ions take place all the time,” Tapia Takaki says. “We had to find a way to record these events without overloading the detector’s bandwidth.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 4:12 pm on December 1, 2015 Permalink | Reply
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    From Nature: “Artificial intelligence called in to tackle LHC data deluge” 

    Nature Mag
    Nature

    01 December 2015
    Davide Castelvecchi

    1
    Particle collisions at the Large Hadron Collider produce huge amounts of data, which algorithms are well placed to process.

    The next generation of particle-collider experiments will feature some of the world’s most advanced thinking machines, if links now being forged between particle physicists and artificial intelligence (AI) researchers take off. Such machines could make discoveries with little human input — a prospect that makes some physicists queasy.

    Driven by an eagerness to make discoveries and the knowledge that they will be hit with unmanageable volumes of data in ten years’ time, physicists who work on the Large Hadron Collider (LHC), near Geneva, Switzerland, are enlisting the help of AI experts.

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

    On 9–13 November, leading lights from both communities attended a workshop — the first of its kind — at which they discussed how advanced AI techniques could speed discoveries at the LHC. Particle physicists have “realized that they cannot do it alone”, says Cécile Germain, a computer scientist at the University of Paris South in Orsay, who spoke at the workshop at CERN, the particle-physics lab that hosts the LHC.

    Computer scientists are responding in droves. Last year, Germain helped to organize a competition to write programs that could ‘discover’ traces of the Higgs boson in a set of simulated data; it attracted submissions from more than 1,700 teams.

    CERN ATLAS Higgs Event
    Higgs Event

    Particle physics is already no stranger to AI. In particular, when ATLAS and CMS, the LHC’s two largest experiments, discovered the Higgs boson in 2012, they did so in part using machine learning — a form of AI that ‘trains’ algorithms to recognize patterns in data.

    CERN ATLAS New
    ATLAS

    CERN CMS Detector
    CMS

    The algorithms were primed using simulations of the debris from particle collisions, and learned to spot the patterns produced by the decay of rare Higgs particles among millions of more mundane events. They were then set to work on the real thing.

    But in the near future, the experiments will need to get smarter at collecting their data, not just processing it. CMS and ATLAS each currently produces hundreds of millions of collisions per second, and uses quick and dirty criteria to ignore all but 1 in 1,000 events. Upgrades scheduled for 2025 mean that the number of collisions will grow 20-fold, and that the detectors will have to use more sophisticated methods to choose what they keep, says CMS physicist María Spiropulu of the California Institute of Technology in Pasadena, who helped to organize the CERN workshop. “We’re going into the unknown,” she says.

    Inspiration could come from another LHC experiment, LHCb, which is dedicated to studying subtle asymmetries between particles and their antimatter counterparts.

    CERN LHCb New II
    LHCb

    In preparation for the second, higher-energy run of the LHC, which began in April, the LHCb team programmed its detector to use machine learning to decide which data to keep.

    LHCb is sensitive to tiny variations in temperature and pressure, so which data are interesting at any one time changes throughout the experiment — something that machine learning can adapt to in real time. “No one has done this before,” says Vladimir Gligorov, an LHCb physicist at CERN who led the AI project.

    Particle-physics experiments usually take months to recalibrate after an upgrade, says Gligorov. But within two weeks of the energy upgrade, the detector had ‘rediscovered’ a particle called the J/Ψ meson — first found in 1974 by two separate US experiments, and later deemed worthy of a Nobel prize.

    In the coming years, CMS and ATLAS are likely to follow in LHCb’s footsteps, say Spiropulu and others, and will make the detector algorithms do more work in real time. “That will revolutionize how we do data analysis,” says Spiropulu.

    An increased reliance on AI decision-making will present new challenges. Unlike LHCb, which focuses mostly on finding known particles so they can be studied in detail, ATLAS and CMS are designed to discover new particles. The idea of throwing away data that could in principle contain huge discoveries, using criteria arrived at by algorithms in a non-transparent way, causes anxiety for many physicists, says Germain. Researchers will want to understand how the algorithms work and to ensure they are based on physics principles, she says. “It’s a nightmare for them.”

    Proponents of the approach will also have to convince their colleagues to abandon tried-and-tested techniques, Gligorov says. “These are huge collaborations, so to get a new method approved, it takes the age of the Universe.” LHCb has about 1,000 members; ATLAS and CMS have some 3,000 each.

    Despite these challenges, the most hotly discussed issue at the workshop was whether and how particle physics should make use of even more sophisticated AI, in the form of a technique called deep learning. Basic machine-learning algorithms are trained with sample data such as images, and ‘told’ what each picture shows — a house versus a cat, say. But in deep learning, used by software such as Google Translate and Apple’s voice-recognition system Siri, the computer typically receives no such supervision, and finds ways to categorize objects on its own.

    Although they emphasized that they would not be comfortable handing over this level of control to an algorithm, several speakers at the CERN workshop discussed how deep learning could be applied to physics. Pierre Baldi, an AI researcher at the University of California, Irvine who has applied machine learning to various branches of science, described how he and his collaborators have done research suggesting that a deep-learning technique known as dark knowledge might aid — fittingly — in the search for dark matter.

    Deep learning could even lead to the discovery of particles that no theorist has yet predicted, says CMS member Maurizio Pierini, a CERN staff physicist who co-hosted the workshop. “It could be an insurance policy, just in case the theorist who made the right prediction isn’t born yet.”

    See the full article here .

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 10:56 am on November 28, 2015 Permalink | Reply
    Tags: , , CERN LHC, Heavy-ion beams, , ,   

    From CERN: “LHC Report: plumbing new heights” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    30 Nov 2015
    John Jowett for the LHC team

    1
    The CCC team after stable heavy-ion beams are declared in the LHC

    Following the end of the arduous 2015 proton run on 4 November, the many teams working on the LHC and its injector complex are naturally entitled to a calmer period before the well-earned end-of-year break. But that is not the way things work.

    Instead, the subdued frenzy of setting up the accelerators for a physics run has started again, this time for heavy-ion beams, with a few additional twists of the time-pressure knob. In this year’s one-month run, the first week was devoted to colliding protons at 2.51 TeV per beam to provide reference data for the subsequent collisions of lead nuclei (the atomic number of lead is Z=82, compared to Z=1 for protons) at the unprecedented energy of 5.02 TeV in the centre of mass per nucleon pair.

    The chain of specialised heavy-ion injectors, comprising the ECR ion source, Linac3 and the LEIR ring, with its elaborate bunch-forming and cooling, were re-commissioned to provide intense and dense lead bunches in the preceding weeks. Through a series of exquisite RF gymnastics, the PS and SPS assemble these into 24-bunch trains for injection into the LHC. The beam intensity delivered by the injectors is a crucial determinant of the luminosity of the collider.

    Commissioning of the LHC’s 2.51 TeV proton cycle had to be interleaved with that of the new heavy-ion optics in the LHC, resulting in many adjustments to the schedule on the fly and specialist teams being summoned at short notice to the CCC.

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    CCC. From Symmetry, Artwork by Sandbox Studio, Chicago

    Besides the overall energy shift compared to the 6.5 TeV proton optics, there is an additional squeeze of the optics and manipulations of crossing angles and the interaction point position for the ALICE experiment. Rapid work by the LHC’s optics measurements and correction team allowed the new heavy-ion magnetic cycle to be implemented from scratch (using proton beams) over the weekend of 14-15 November. Members of the collimation team also spent many hours on careful aperture measurements. At every step, one must be mindful of the strict requirements of machine protection.

    The first lead-ion beams were injected on the evening of Monday, 16 November and brought into collision in all four experiments, by a bleary-eyed team, 10 hours later in the early morning.

    The proton reference run resumed that Tuesday evening. After some unnerving down time, its luminosity target was comfortably attained on Sunday morning and the ion commissioning resumed with more aperture measurements and the process of verifying the “loss maps” to confirm that errant beam particles fetch up where they can do the least harm. These are very different from those of protons because of the many ways in which the lead nuclei can fragment as they interact with thecollimators. A penultimate switch of particle species provided a bonus of proton reference data to the experiments overnight.

    Finally, on 23 November the lead ions had the LHC to themselves and commissioning resumed with tuning of injection, RF and feedback systems. And many more loss maps.

    Stable beams for physics with 10 bunches per beam was finally declared at 10:59 on 25 November and spectacular event displays started to flow from the experiments. Further fills should increase the number of bunches beyond 400.

    The remaining weeks of the run will continue to be eventful with physics production interrupted by ion-source oven refills, van der Meer scans, solenoid polarity reversals and studies of phenomena that may limit future performance. These include tests of magnet quench levels with collimation losses and the use of crystals as collimators. We also plan to test strategies for controlling the secondary beams emerging from the collision point due to ultraperipheral (“near miss”) interactions.

    See the full article here.

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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 12:13 pm on November 26, 2015 Permalink | Reply
    Tags: , , CERN LHC, Linac 4   

    From CERN: “Release the beams! Linac 4 hits the 50 MeV mark” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    26 Nov 2015
    Harriet Kim Jarlett

    1
    The Linac 4 tunnel where DTL tubes guide the 50MeV beam, taken on the Photowalk (Image: Andrew Hara/CERN)

    This week the Linac 4 accelerator has reached a milestone energy of 50 MeV – meaning it is now able to replace the ageing Linac 2 and eventually become the head of the accelerator chain .

    Linac 4 was built to boost negative hydrogen ions – consisting of a hydrogen atom with an additional electron – to high energies to provide protons to the Large Hadron and to replace the Linac 2. This 37-year-old accelerator is the first in a series of four, which are boosting particles to higher and higher energies before they are injected into the Large Hadron Collider (LHC). These accelerators are also providing beams to many other experiments at CERN.

    Eventually Linac 4 will accelerate ions to 160 MeV to prepare them to enter the Proton Synchrotron Booster – the second acclerator in the LHC injection chain.

    3
    Proton Synchrotron Booster

    These ions are stripped of their two electrons during injection from Linac 4 into the Proton Synchrotron Booster to leave only protons. This allows more particles to accumulate in the synchrotron, simplifies injection, reduces beam loss at injection and gives a more brilliant beam. As a key part of the LHC injector upgrade programme, Linac 4 will allow the PS Booster to double its beam brightness, which will contribute to increasing the LHC’s luminosity, a crucial factor proportional to the number of particles colliding within a defined amount of time.

    2
    A photo montage from the 2015 photowalk, with Maurizio Vretenar, the Linac 4 project leader, alongside both the designs for and the constructed accelerator 2015 (Image: Maelle Baud/CERN)

    Reaching 50MeV is a milestone as it’s the energy Linac 2 runs at, and means Linac4 is now capable of taking over the task of providing particles to CERN’s accelerator chain – a process that will begin during the long shutdown from 2018.

    The Linac 4 is composed of a hydrogen ion source and four types of accelerating structures which are progressively commissioned one after another. Earlier this year the second part of this accelerating chain, the Drift Tube Linac tanks were fully installed and commissioned, meaning the beam could be boosted to a new, higher, energy from its previous 3 MeV.

    “This innovative and patented design is a huge achievement that was eight years in the making,” says Maurizio Vretenar, the Linac 4 project leader. “We saw these tanks through from the drawing board to the test bench, and now to the accelerator chain itself; we couldn’t be happier with their performance so far.”

    Ensuring faultless connections between the seperate accelerator components was a key part of the commissioning process. The tubes and their components had to be aligned with ±0.1 mm precision to each other and to the rest of the Linac 4 line.

    “The first step was to accelerate the beam through the first tank of the DTL, to find the correct settings of the low energy part,” says Alessandra Lombardi, who is in charge of the commissioning phase of Linac 4. We then accelerated the beam progressively through the second and the third tank to the energy of 50 MeV.”

    Now the beam has reached 50 MeV, the Linac 4 team is moving on to the next item on the schedule: the Cell-Coupled DTLs (CCDTL), which will bring Linac 4 up to 100 MeV.

    See the full article here.

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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

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  • richardmitnick 5:16 pm on November 25, 2015 Permalink | Reply
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    From ALICE at CERN: “LHC collides ions at new record energy” 

    CERN New Masthead

    CERN ALICE Icon HUGE

    1
    Lead ions collide in the CMS detector (Image:CMS)

    After the successful restart of the Large Hadron Collider (LHC) and its first months of data taking with proton collisions at a new energy frontier, the LHC is moving to a new phase, with the first lead-ion collisions of season 2 at an energy about twice as high as that of any previous collider experiment. Following a period of intense activity to re-configure the LHC and its chain of accelerators for heavy-ion beams, CERN’s accelerator specialists put the beams into collision for the first time in the early morning of 17 November 2015 and ‘stable beams’ were declared at 10.59am today, marking the start of a one-month run with positively charged lead ions: lead atoms stripped of electrons. The four large LHC experiments will all take data over this campaign, including LHCb, which will record this kind of collision for the first time. Colliding lead ions allows the LHC experiments to study a state of matter that existed shortly after the big bang, reaching a temperature of several trillion degrees.

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    Lead ions collide in the ALICE detector (Image:ALICE)

    “It is a tradition to collide ions over one month every year as part of our diverse research programme at the LHC,” said CERN Director-General Rolf Heuer. “This year however is special as we reach a new energy and will explore matter at an even earlier stage of our universe.”

    Early in the life of our universe, for a few millionths of a second, matter was a very hot and very dense medium – a kind of primordial ‘soup’ of particles, mainly composed of fundamental particles known as quarks and gluons. In today’s cold Universe, the gluons “glue” quarks together into the protons and neutrons that form bulk matter, including us, as well as other kinds of particles.

    “There are many very dense and very hot questions to be addressed with the ion run for which our experiment was specifically designed and further improved during the shutdown,” said ALICE collaboration spokesperson Paolo Giubellino. “For instance, we are eager to learn how the increase in energy will affect charmonium production, and to probe heavy flavour and jet quenching with higher statistics. The whole collaboration is enthusiastically preparing for a new journey of discovery.”

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    Lead ions collide in the LHCb detector (Image: LHCb)

    Increasing the energy of collisions will increase the volume and the temperature of the quark and gluon plasma, allowing for significant advances in understanding the strongly-interacting medium formed in lead-ion collisions at the LHC. As an example, in season 1 the LHC experiments confirmed the perfect liquid nature of the quark-gluon plasma and the existence of “jet quenching” in ion collisions, a phenomenon in which generated particles lose energy through the quark-gluon plasma. The high abundance of such phenomena will provide the experiments with tools to characterize the behaviour of this quark-gluon plasma. Measurements to higher jet energies will thus allow new and more detailed characterization of this very interesting state of matter.

    “The heavy-ion run will provide a great complement to the proton-proton data we’ve taken this year,” said ATLAS collaboration spokesperson Dave Charlton. “We are looking forward to extending ATLAS’ studies of how energetic objects such as jets and W and Z bosons behave in the quark gluon plasma.”

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    Lead ions collide in the ATLAS dectector (Image: ATLAS)

    The LHC detectors were substantially improved during the LHC’s first long shutdown. With higher statistics expected, physicists will be able to look deeper at the tantalising signals observed in season 1.

    “Heavy flavour particles will be produced at high rate in Season 2, opening up unprecedented opportunities to study hadronic matter in extreme conditions,” said CMS collaboration spokesperson Tiziano Camporesi. « CMS is ideally suited to trigger on these rare probes and to measure them with high precision. »

    For the very first time, the LHCb collaboration will join the club of experiments taking data with ion-ion collisions.

    “This is an exciting step into the unknown for LHCb, which has very precise particle identification capabilities. Our detector will enable us to perform measurements that are highly complementary to those of our friends elsewhere around the ring,” said LHCb collaboration spokesperson Guy Wilkinson.

    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
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 2:12 pm on November 25, 2015 Permalink | Reply
    Tags: , , , CERN LHC, , , ,   

    From Symmetry: “Revamped LHC goes heavy metal” 

    Symmetry

    11/25/15
    Sarah Charley

    Physicists will collide lead ions to replicate and study the embryonic universe.

    “In the beginning there was nothing, which exploded.”

    ~ Terry Pratchett, author

    For the next three weeks physicists at the Large Hadron Collider will cook up the oldest form of matter in the universe by switching their subatomic fodder from protons to lead ions.

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

    Lead ions consist of 82 protons and 126 neutrons clumped into tight atomic nuclei. When smashed together at extremely high energies, lead ions transform into the universe’s most perfect super-fluid: the quark gluon plasma. Quark gluon plasma is the oldest form of matter in the universe; it is thought to have formed within microseconds of the big bang.

    “The LHC can bring us back to that time,” says Rene Bellwied, a professor of physics at the University of Houston and a researcher on the ALICE experiment.

    CERN ALICE Icon HUGE
    CERN ALICE New
    ALICE at CERN

    “We can produce a tiny sample of the nascent universe and study how it cooled and coalesced to make everything we see today.”

    Scientists first observed this prehistoric plasma after colliding gold ions in the Relativistic Heavy Ion Collider [RHIC], a nuclear physics research facility located at the US Department of Energy’s Brookhaven National Laboratory.

    BNL RHIC Campus
    BNL RHIC
    RHIC

    “We expected to create matter that would behave like a gas, but it actually has properties that make it more like a liquid,” says Brookhaven physicist Peter Steinberg, who works on both RHIC and the ATLAS heavy ion program at the LHC. “And it’s not just any liquid; it’s a near perfect liquid, with a very uniform flow and almost no internal resistance.”

    The LHC is famous for accelerating and colliding protons at the highest energies on Earth, but once a year physicists tweak its magnets and optimize its parameters for lead-lead or lead-proton collisions.

    The lead ions are accelerated until each proton and neutron inside the nucleus has about 2.51 trillion electronvolts of energy. This might seem small compared to the 6.5 TeV protons that zoomed around the LHC ring during the summer. But because lead ions are so massive, they get a lot more bang for their buck.

    “If protons were bowling balls, lead ions would be wrecking balls,” says Peter Jacobs, a scientist at Lawrence Berkeley National Laboratory working on the ALICE experiment. “When we collide them inside the LHC, the total energy generated is huge; reaching temperatures around 100,000 times hotter than the center of the sun. This is a state of matter we cannot make by just colliding two protons.”

    Compared to the last round of LHC lead-lead collisions at the end of Run I, these collisions are nearly twice as energetic. New additions to the ALICE detector will also give scientists a more encompassing picture of the nascent universe’s behavior and personality.

    “The system will be hotter, so the quark gluon plasma will live longer and expand more,” Bellwied says. “This increases our chances of producing new types of matter and will enable us to study the plasma’s properties more in depth.”

    The Department of Energy, Office of Science, and the National Science Foundation support this research and sponsor the US-led upgrades the LHC detectors.

    Bellwied and his team are particularly interested in studying a heavy and metastable form of matter called strange matter. Strange matter is made up of clumps of quarks, much like the original colliding lead ions, but it contains at least one particularly heavy quark, called the strange quark.

    “There are six quarks that exist in nature, but everything that is stable is made only out of the two lightest ones,” he says. “We want to see what other types of matter are possible. We know that matter containing strange quarks can exist, but how strange can we make it?”

    Examining the composition, mass and stability of ‘strange’ matter could help illuminate how the early universe evolved and what role (if any) heavy quarks and metastable forms of matter played during its development

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:28 pm on November 25, 2015 Permalink | Reply
    Tags: , , CERN LHC, , , ,   

    From WIRED: “Physicists Are Desperate to Be Wrong About the Higgs Boson” 

    Wired logo

    Wired

    11.24.15
    Signe Brewster

    1
    A visitor stands in front of a large image of the Large Hadron Collider at the London Science Museum’s ‘Collider’ exhibition. Peter Macdiarmid/Getty Images

    When Paul Glaysher was approaching the end of his master’s degree in 2012, everyone was talking about the Higgs boson. After two years of smashing protons together, CERN’s Large Hadron Collider was about to bring the mysterious particle—it helps explain how the universe got its mass—out of the theoretical realm.

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

    Students who landed a spot on a LHC research team had a chance to aid the biggest discovery in modern physics.

    Glaysher bit. Then, two months before he started his PhD program with the University of Edinburgh’s CERN team, the LHC’s ATLAS and CMS experiments announced they had found the Higgs boson.

    CERN ATLAS New
    ATLAS

    CERN CMS Detector
    CMS

    CERN CMS Event
    Higgs event

    “It was a bit sad,” Glaysher says. “They waited 50 years to find it, and couldn’t wait the extra two months until I was part of the party.”

    The three years that followed were a champagne-fueled hangover. Further data confirmed the Higgs discovery, and then the collider shut down for a two-year upgrade that more than doubled its particle-smashing power.

    This summer, the LHC’s long-awaited restart came with a new promise: the chance to spot larger particles never before created in a human-made particle accelerator. Physicists believe they might glimpse the particles that make up dark matter—the unknown substance thought to make up a quarter of the universe—or even hints of other dimensions.

    But despite the chance to study exotic new particles, Glaysher finds himself three and a half years later still studying the Higgs boson for the ATLAS experiment. Instead of spending his entire life chasing a specter, he’s examining something very real.

    “Discovery—as exciting as it is, as Nobel-prize-generating as it may be—it’s actually just the first step,” Glaysher says. Theorists and other researchers at the collider agree with him. They think the Higgs could find them some new physics yet.

    What Now?

    The Higgs was, in a way, the end of the line. At the heart of particle physics is what’s known as the Standard Model: a group of 17 elementary particles and the rules for how they should interact.

    3
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Up until the Higgs discovery, physicists had observed 16 of these particles—and the field was desperate for a 17th that would push the model in new directions. But the Higgs turned out to be totally ordinary. It acted just like the model said it would act, obeyed every theorized rule.

    The physicists, in other words, had done too good of a job with their predictions. “With the Higgs, we thought we had touched the bottom,” says Andre David, a CMS research physicist leading the effort to characterize the boson.

    But with a newly-upgraded LHC, the ATLAS researchers—along with their counterparts at CMS and theoretical physicists—think the Higgs could yet lead to new insights about the nature of the world. “It’s like you’ve pierced the bottom and there must be a new bottom,” says David. “You just have to keep digging.”

    So far, the scientists have some juicy theories for the Higgs. When you’re part of the process responsible for giving the universe mass, it’s likely you’re mixed up in some other interesting business. This month marked the completion of the LHC’s first round of observing proton collisions at a higher energy, and the data collected could play into some of physics’ biggest questions.

    One of physicists’ greatest hopes for the new LHC is to not upend the Standard Model with new observations, but to extend it—by finding a partner for each of its 17 particles, validating a theory called supersymmetry.

    Supersymmetry standard model
    Standard Model of Supersymmetry

    The Standard Model has a good explanation for the weak force, which allows one particle to turn into another. But physicists don’t know why the weak force is able to overpower gravity. Theories that explained that weirdness called for a Higgs with a huge mass, but the boson discovered in 2012 was relatively light. Observing supersymmetric particles that are also light could account for the discrepancies.

    The Higgs could play a role in another unobserved particle, too: dark matter. It’s possible that the Higgs likes to turn into dark matter, or play some other role in its behavior. The LHC’s huge detectors measure what happens after collisions by detecting the energies of the resulting particles—and if part of the energy disappears, it could be a hint that dark matter appeared.

    Then there’s matter and antimatter. While physicists have documented both, they aren’t sure what happened right after the Big Bang, when the universe was still made of equal parts matter and antimatter. The two have a tendency to destroy each other and turn into pure energy when they collide. But something caused an imbalance, leading to a modern universe that has far more matter than antimatter. Physicists believe the Higgs’ interactions with itself could have played a part—so they plan to study what happens when two Higgs meet in the LHC.

    Finally, physicists believe they could find even more Higgs particles. One prominent theory holds that instead of one type of Higgs boson, there are five. Some of them are much heavier than the Higgs found in 2012, which means the LHC may not have been powerful enough to create them. Until now.

    The Known Unknown

    Those are all tantalizing possibilities. Still, the LHC’s most intriguing results could come from seeing something that nobody predicted. The Higgs discovered in 2012 happens to have a mass that is suspiciously compatible with a huge number of particle interactions. That could be a coincidence. Or—hope beyond hope—it could lead to an underlying principle that physicists have missed until now. The end goal, as always, is to find a string that, when tugged, rings a clarion bell that draws physicists toward something new.

    “It’s not guaranteed we have thought everything that can be thought of. It might just be we are not imaginative and creative enough,” David says. “We might be going in a direction where new physics could be subtle. It’s not like a new particle in your face.”

    Scientists are, once again, starting the clock on a nebulous waiting period. Peter Higgs theorized the boson in 1964—and then the particle went unobserved for 50 years. CERN’s teams don’t know whether their current collider is powerful enough to provide the answers they seek, or if they will have to wait for a major energy upgrade years or even decades from now.

    “We have lots of questions. We have indirect evidence that they might be answered by the experiments we’re doing,” says ATLAS researcher Elliot Lipeles. “We might come up empty, or we might find a shocking discovery literally next month.”

    It’s tedious and generally unglamorous work. Glaysher’s group at the University of Edinburgh spends its days analyzing instances of the Higgs decaying into several specific types of particles. To uncover the Higgs’ secrets, it’s up to physicists to spend thousands of hours combing through the unfathomable number of particle collisions produced each day in the LHC. And if Glaysher is lucky, his team might be the one to find out physics has got the Higgs all wrong.

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 11:54 am on November 20, 2015 Permalink | Reply
    Tags: , , CERN LHC, , , , ,   

    From FNAL- “Frontier Science Result: CMS Lead bottom” 

    FNAL II photo

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

    Nov. 20, 2015
    FNAL Don Lincoln
    Don Lincoln

    1
    Today’s article describes what happens when you collide individual protons into lead nuclei. This result helps understand an exciting new state of matter called a quark gluon plasma. Image: CERN

    The nice thing about the LHC research program is that it allows scientists to investigate many phenomena.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    All are exotic, with some pushing the very frontier of knowledge, while some investigate complex phenomena as a means to understand even more complex phenomena.

    When two heavy atomic nuclei are slammed together at very high energy, a peculiar thing occurs. The temperatures in these collisions are so high that the protons and neutrons in the nuclei literally melt, and the quarks and gluons that are normally inside the protons and neutrons can move around freely. We call this state of matter a quark-gluon plasma.

    In addition, the high collision energy can convert into matter-antimatter pairs, as suggested by Einstein’s equation E=mc2. If you want to study what occurs in the collision, you look for types of matter that don’t exist as ordinary matter. One example of this more exotic type of matter is bottom quarks. Since they don’t generally exist inside the nuclei of atoms, if you see bottom quarks, you know that they were made from the energy of the collision.

    Scientists have lots of experience making bottom quarks by colliding two protons together. This is the way we run the LHC for most of the time, and we have made (although not recorded) many billions of bottom quarks. The process is pretty well-understood.

    We also can make bottom quarks by colliding two lead nuclei together. We do this at the LHC about one month per year. In these collisions, a total of 416 protons and neutrons are smashed together. Naively, you’d expect that all the protons and neutrons can participate in the collision and that the number of bottom quarks that are made can be easily calculated from the well-understood proton-proton scattering process.

    However, we see fewer bottom quarks than we’d expect from lead-lead collisions. The usual explanation is that these bottom quarks have to push their way through the hot quark-gluon plasma. They become tired and slow down, so they don’t escape the collision.

    But there might be other explanations. Maybe the fact that the colliding protons and neutrons are bound in nuclei (rather that floating freely) influences how their component quarks and gluons are distributed inside them.

    To work out this ambiguity, CMS scientists decided to smash together a beam of protons into a beam of lead nuclei.

    CERN CMS Detector
    CMS

    If the lower-than-expected number of bottom quarks in lead-lead collisions was due to the way bottom quarks plow through quark-gluon plasma you’d expect to see no reduction in the production of bottom quarks from these lead-proton collisions, since the quark-gluon plasma is not made in these kinds of collisions. If the effect was due to the moving around of energy inside nuclei, you’d expect to see behavior midway between the proton-proton and lead-lead scattering.

    As it happens, scientists observed no reduction in the production of bottom quarks. This strongly suggests that the reduction seen in collisions between two lead nuclei originates in the bottom quarks trying to punch through the quark gluon plasma. Thus this measurement validates our understanding of the behavior of matter hot enough to melt protons and neutrons.

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

     
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