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  • richardmitnick 10:48 am on March 31, 2015 Permalink | Reply
    Tags: , , , Particle Accelerators,   

    From ALICE at CERN: “Interview with Savas Dimopoulos” 

    CERN New Masthead

    CERN ALICE Icon HUGE

    24 March 2015
    Panos Charitos

    1
    Savas Dimopoulos

    Savas Dimopoulos, professor at Stanford University, is searching for answers to some of the most profound mysteries of nature. In this interview we discuss the recent findings of the LHC and his expectations from future HEP experiments, the quest for “truth” that drives our scientific endeavours, as well as the relation between science and art.

    P.C. Why did you decide to become a physicist?

    S.D. What attracted me to physics and mathematics was the truth of the statements made in these disciplines. This dates back to my childhood. I was born in Constantinople, and my family moved to Athens when I was twelve. It was a time of great turmoil and I witnessed political tensions, people on the left and on the right were expressing opposing arguments that both seemed reasonable to me.

    I decided to go into a discipline that seeks the absolute truth: a truth that does not depend on the eloquence of the speaker. That limited my choices to mathematics and physics. I finally decided to study physics, as I had doubts about the certainty of truth in mathematics; in physics, in addition to mathematical proofs, the experiments add an extra layer of certainty that brings us closer to the truth.

    I was enamoured of the fact that through physics we can explain all phenomena from very few principles, as nature turns out to be exceedingly simple in principles and exceedingly complex in phenomena. The laws of nature can be written down on a single piece of paper and explain everything that we have seen so far in the universe. This is the magic of theory: it compactifies facts and reduces them to a handful of principles from which everything can be derived.

    P.C. You referred to the balance between experiment and theory, but it somehow seems that you were more intrigued by the latter. What attracted you to what is now called theoretical physics?

    S.D. In the beginning, I had not decided whether I was going to be a theorist or an experimentalist. I went to a high-school without laboratories in Greece. The first time I had the chance to work in a laboratory was as a student at the university. That’s when I realised that I lacked the talent to be an experimentalist and felt that I was better in theory.

    At the time, I thought that the truth of mathematics exists only in our human brains, whereas physics is independent of human existence and therefore the ultimate discipline for the search for the absolute and most important truths. Plato believed that mathematical reality in some sense exists in the so-called platonic world of ideas, where objects on earth have their idealized counterparts. A sphere, for example, is never perfect in real life but in the platonic world, which we call mathematics, perfectly round spheres exist. As mathematical entities are not necessarily realized in nature, I felt uncomfortable as a child to just focus on mathematics. However, I think that it is an amazing language. The rules are well defined and once you pose the right question anybody can follow the steps to find the correct answer, even computers.

    P.C. Do you think that, besides experiments, mathematics is also another way to control our theories?

    S.D. You are absolutely right. Mathematics is crucial for controlling the truth because it is not a random game. You start with a few axioms, and, as long as they are self-consistent, you can produce theorems and derive truths that follow from them. In that sense, mathematics is very important to theoreticians, as mathematical consistency is a huge constraint on our theoretical ideas.

    P.C. What is the situation today in theoretical physics, following the recent results of the LHC?

    S.D. We are now standing at a crossroads, with one path leading to naturalness and the other to the multiverse or something else. It is very exciting, we are testing if the idea of naturalness can be applied to the hierarchy problem – which is the disparity between the weak and gravitational forces. In the next several years, the LHC will be the epicentre of excitement, because it is testing such a fundamental principle and such a dichotomy in physics.

    In the light of these data, physicists react in different ways. As I often emphasize in my recent talks, the state of beyond Standard Model physics after the LHC8 can be compared to headless chickens running in all possible directions.

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    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom)

    What is more interesting, headless chickens can live for up to two years; that is also the timescale which we need to get more results from the second run of the LHC. This run will indicate the research that we will pursue in the coming decades.

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    Mixed reactions should not frighten us, as they characterize every scientific revolution.

    P.C. Why do you believe there is so much enthusiasm for the search of supersymmetry at the LHC?

    Supersymmetry standard model
    Standard Model of Supersymmetry

    S.D. People are enthusiastic about the possibility of discovering supersymmetry for a number of reasons. In the early 1990s, LEP measured the strengths of the strong and weak electromagnetic interactions and discovered that supersymmetric grand unification is favoured over the non-supersymmetric one. That was a great source of excitement, and theorists looked forward to discovering the super-partners at LEP, LEP 2, or at the LHC. However, no hint of supersymmetry was found after the first collisions at the LHC8 energies.

    CERN LEP
    CERN/LEP

    This story reminds me one of Sherlock Holmes’ stories where he points out “the curious incident of the dog in the night-time”, the incident being that the dog did nothing. In the same way, the absence of supersymmetry at the energies explored so far at the LHC can teach us many things. Supersymmetry is one of the rare ideas that is so important, that even its absence is worth knowing about.

    In addition to that, there is also a sociological aspect to the popularity of supersymmetry: it is an easy theory to work with, and, as a result, it can be tested experimentally in great detail, unlike other alternatives to the hierarchy problem.

    Because of these reasons, the search for supersymmetry is the [?]primary aim of the LHC. In the next years we should have a better idea of the path chosen by nature and we may be talking with enthusiasm about the discovery of the first supersymmetric particle. In the best case scenario, though, our theories will be proven wrong, and we will discover something unanticipated, something truly revolutionary as was the case with quantum mechanics.

    P.C. How did it feel to have your prediction of unification of couplings confirmed by experiment?

    S.D. Having your theory confirmed by experiment feels like a present that you didn’t deserve. When we do science on a day-to-day basis, it’s sort of like a puzzle – this very intricate game with strict rules. It’s like nature is a giant puzzle and mathematics is the language of nature. When a mathematical theory is verified by experiment, you feel awe. It somehow becomes real. You get amazed when you realize that all these games you have been playing are not just games but actually describe nature.

    P.C. Do you think LHC will have the last word or will we also need to design new experiments?

    S.D. There are two directions that we should pursue vigorously. One is to continue with colliders, and go to much higher energy. The other is to design new experiments, as there are some great theoretical ideas that cannot be tested in colliders. For example, some very weakly interacting new particles such as the axion can only be discovered in low energy, tabletop, small-scale experiments.

    There can be forces that are too weak to be discovered in colliders but can nevertheless be observed by testing gravity-like forces in small scale. For example, one can look for deviations from Newton’s law at short distances. In addition to the theoretical importance, many fields (i.e. condensed matter physics, atomic physics, quantum information) have made great progress in precision studies, and these new techniques are begging to be used for fundamental discoveries. They also have the sociological advantage of shorter timescales, typically less than five years, compared to those between two consecutive colliders, which can be decades.

    Another interesting point is that you can roughly separate physics to two periods. Before WWII a number of techniques were used to explore the truth, and the job of theoreticians was both to come up with theoretical ideas and to design experiments to test them. Enrico Fermi and Felix Bloch, for example, did not just do theory; they came up with experiments and, in some cases, even conducted them themselves. After the War, fundamental physics started focusing increasingly on the high energy frontier. This has been a golden road, as the recent discovery of the Higgs shows. Nevertheless, in the long timescale between consecutive colliders, it will be exciting to look for new physics using low energy experiments.

    P.C. Do you think that we still learn something, even when our theories are proven wrong? Is this another step bringing us closer to truth?

    S.D. Absolutely. Truth is both discovering new things and proving that some preconceptions, speculations, or theories are wrong. For example, the idea of the aether seemed plausible at a time, as it was logical to assume that electromagnetic waves need a medium, but it was disproved by the Michelson–Morley experiment. In this case, it was the non-discovery of something that created the big earthquake that led to relativity. Knowing what is false can be as important as knowing what is true.

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    P.C. What drives people to formulate new theories and models?

    S.D. One obvious reason is the inconsistency of an existing theory with data. The Standard Model has survived every laboratory test so far and in some cases the validity of its predictions has been tested to 12 decimal precision. It nevertheless fails to explain roughly 95% of our Cosmos. It does not explain Dark Matter or what the origin of Dark Energy is. For the latter, the SM prediction is at least 60 orders of magnitude larger than what we observe it to be. In addition to all this, we eventually run into theoretical problems once we extrapolate the theory to high energies.

    The other motivations are beauty and economy. In the context of physics, the idea of beauty has a relatively precise meaning: it involves symmetry, i.e. the idea that one object appears the same from different perspectives. Economy refers to economy of structure, particles, and parameters. Ideally, there are as few “moving parts” postulated into the theory as possible. In that sense, it is hard to believe that the Standard Model, despite being an amazing theory, is fundamental, because it has over twenty parameters and tens of particles. There must be a more economic version.

    A philosophical, more reflective reason for doing theory is our love of patterns. We are pattern junkies. In our effort to find harmony and conceptually beautiful ways to understand everything at the deepest possible level we do science or create art. Neither of them directly enhances or contributes to our survival probability, but the least important things for our survival are the very things that make us human. For me, art and science are equally important; after a hard day of research I listen to music and find these patterns very relaxing because they are beautiful, and also because I don’t have to actively scrutinise them.

    P.C. Is it possible that at some point we will have answered all the fundamental questions and the scientific endeavours will come to an end?

    S.D. Humans tend to be quite dismissive of the things they learn. There is a famous saying: “Yesterday’s sensation, today’s calibration, tomorrow’s background”. We get bored, and want to move immediately to the next level. For many decades, if not centuries, we have been trying to find a model that explains all the interactions to any conceivable energy that we have experimented with so far. We came up with the Standard Model that may describe almost all known phenomena, but now we want to effectively build a meta-theory that explains the theory itself. However, I am sure that even if we find this meta-theory, we will still come up with more questions. That’s what makes us, as humans, a progressive species: we get excited, we investigate, we discover, and then we get bored and want to get excited again by moving to the next questions.

    P.C. Do you think that the social context is still in favour of researching particle physics and fundamental questions?

    S.D. I think that the public is very interested in fundamental physics. Physics enrollment at universities like Stanford has been going steadily up for the last 15 years at undergraduate and graduate level, despite the fact that there are more competing disciplines, such as biology and information technology. I have also received a lot of positive feedback from the movie Particle Fever.

    However, when the producer approached me ten years ago and told me that he wanted to make a movie about particle physics, I said: “That sounds boring. Who cares about particle physics? You are wasting your time”. “It’s not about particle physics,” he replied, “it’s about particle physicists”. I said: “This is even worse. They are the plainest people on the planet”. I was proven blatantly wrong. And it’s not just Particle Fever. This year there are several movies about science: Gravity, Interstellar, the Imitation Game that is about Alan Turing, and The Theory of Everything about Steven Hawking.

    I think that part of the reason why many more young people don’t go into physics in general and particle physics in particular is that we are not very good at communicating the sense of excitement or even the practical importance of our discoveries to the public. If more effort is put in that direction, it will do wonders to attract bright young people.

    Outreach is a little easier for astrophysicists and cosmologists, because people can lift their eyes to the sky and see what they talk about. Our job, however, is to explain that big entities consist of small parts, which, in a sense, are more fundamental.

    In my experience, two books that I read when I was twelve played a big role in my choosing to be a physicist. One was by Einstein and Infeld and the other was a biography of Einstein by Philipp Frank.

    P.C. Maybe this is the right time to ask you, as a teacher now, what’s your main advice to your students?

    S.D. Enjoy yourself and work on the biggest problems that you can tackle.

    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 12:53 pm on March 27, 2015 Permalink | Reply
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    From CMS at CERN/LHC: “CMS is never idle” 

    CERN New Masthead

    2015-03-27
    André David and Dave Barney

    CERN CMS New II

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    Before proton collisions take place again at the LHC, the CMS detector has been looking at the result of collisions of cosmic particles high up in the atmosphere. This event display shows the track of a muon that reached the CMS detector 100 m underground and passed through the muon chambers (in red) and the silicon tracker (in yellow). Muons as this one are used to calibrate the detector in advance of proton collisions.

    CMS is eager to see the first collisions of the LHC Run2. The recent news that the LHC restart may be delayed because of a hardware issue gives us extra time to prepare for those collisions. Far from being idle waiting for collisions, CMS is busy taking advantage of other types of collision.

    CMS is never idle. Without beams, the data-taking does not stop: collisions of cosmic particles high up in the atmosphere produce showers of particles, including muons. Some of these muons have high enough energies to penetrate through the 100 m of ground over the CMS detector and traverse it, leaving behind a trail of dots in our detectors. By connecting the dots, we can learn where the different detector components are inside the huge volume (~3700m3) of CMS to better than a millimetre. This is very important because the whole detector was taken apart and put back together in preparation for Run2. With the cosmic ray muons, we can also synchronise the different detectors down to one hundred-millionth of a second, given that cosmic muons interact with many detectors as they cross the experiment. After a long shutdown, we are also coming back to operating the experiment 24 hours a day, 7 days a week. There is always a shift crew operating and monitoring the experiment, an larger crew of experts that stand ready to intervene in case issues arise, and an even larger community that checks the quality of the data collected. So we exploit this cosmic debris to understand out detectors to the needed precision to later find again the Higgs boson and possibly new, as-yet undiscovered, particles; the more cosmic muon signals we record and analyse, the better prepared we will be to tackle proton collisions at 13 TeV.

    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 1:02 pm on March 26, 2015 Permalink | Reply
    Tags: , , J-PARC, Particle Accelerators,   

    From AAAS: “Shuttered Japanese proton accelerator nears restart” 

    AAAS

    AAAS

    25 March 2015
    Dennis Normile

    Idled after a radiation leak in May 2013, the Japan Proton Accelerator Research Complex (J-PARC) in Tokaimura took a step toward resuming full operations yesterday when the governor of Ibaraki Prefecture accepted a set of countermeasures aimed at preventing another accident. If the facility passes a final inspection by Japan’s Nuclear Regulation Authority, J-PARC could resume normal operations by the end of next month.

    Japan Proton Accelerator Research Complex J-PARC
    J-PARC

    It has been a long slog. An independent investigative panel convened by J-PARC concluded that the accident resulted from a combination of equipment malfunction and human error. In J-PARC’s Hadron Experimental Facility, a proton beam from a 50-GeV synchrotron strikes a target to produce a variety of secondary subatomic particles, including kaons, pions, and muons for use in experiments to determine their characteristics and interactions. On 23 May 2013, a malfunction sent a brief, unexpectedly high intensity beam at a gold target and vaporized radioactive material leaked into the experiment hall. Unaware of what had happened, researchers and staff inhaled contaminated air and also vented it outside the building. J-PARC took 34 hours to notify local and national authorities of the accident. All experiments were halted pending an investigation.

    The expert panel later determined that 34 people had inhaled the vapors and received slight internal radiation exposure that wasn’t deemed harmful and that the release outside the building posed no threat to area residents or the environment. Nonetheless, J-PARC, operated jointly by the High Energy Accelerator Research Organization and the Japan Atomic Energy Agency, then had to convince local and national authorities they could resume operating the facility without endangering staff or the community.

    The countermeasures developed over the past 2 years include upgrading schemes to minimize the impact of equipment glitches, making key experimental chambers airtight, fitting ventilation equipment with filters, and upgrading radiation monitoring and alarm systems. Researchers and staff have received safety training. Designated, trained emergency response personnel will be on hand at all times during operations and J-PARC will conduct accident drills several times annually.

    Experiments resumed at J-PARC’s Materials and Life Science Experimental Facility in February 2014 and at the Neutrino Experimental Facility last May after reviews and strengthening of safety programs.

    J-PARC Neutrino Experimental Facility
    J-PARC Neutrino Experimental Facility Tunnel
    J-PARC Neutrino Experimental Facility

    But more extensive work was needed in the hadron facility. The upgrades were accepted by the prefecture’s own panel of experts earlier this month. Yesterday’s presentation to the governor was largely symbolic. Starting next week, J-PARC officials will explain their strengthened safety measures at three public meetings in nearby towns. The final green light must come from the Nuclear Regulation Authority, which will inspect the facility next month.

    See the full article here.

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 2:29 pm on March 19, 2015 Permalink | Reply
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    From LC Newsline: “Updating the physics case for the ILC” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    19 March 2015

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    Hitoshi Yamamoto

    Director’s Corner

    1

    The physics case of the ILC has been studied intensively for many years, culminating in the physics volume of the Technical Design Report (TDR).

    ILC schematic
    ILC

    It was followed by efforts to compare various machines such as the European Strategy studies and the Snowmass studies. Still, the scientific and political environments surrounding the ILC keep changing. On the scientific front, the LHC has found the Higgs particle and placed limits on new physics.

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

    The LHC is now upgrading the energy and a new run is about to start. On the political side, the committees of the MEXT in Japan are evaluating the case for the ILC both technically and scientifically. It is thus important that we continue to update the physics case for the ILC and communicate it to relevant people.

    The task of updating the physics case for the ILC largely lies on the shoulders of the physics working group of the LCC. With the members of the MEXT committees as audience in mind, they have produced a document called Precis of the Physics Case for the ILC. This turned out to be an extremely useful document for newcomers such as incoming graduate students to learn about the physics of the ILC. It was, however, a little too technical for the audience originally intended. To fill the gap, it was followed by a shorter document intended really for general public – Scientific Motivations for the ILC. This latter document is now mostly ready for distribution. The content of these documents are used by members of those committees in their discussions.

    When evaluating the competitiveness of the ILC, we need to consider circular electron-positron colliders as well as a luminosity-upgraded LHC. At present, there are two studies on next-generation circular electron-positron collider: one at CERN and another in China. The one at CERN is called the FCC (Future Circular Collider) study the main part of which is a proton-proton collider with an optional electron-positron collider to start with. It would start after the LHC ends around 2035. The stated timing of the Chinese circular electron-positron collider, called CEPC, is earlier and about the same as that of the ILC. The CEPC is a Higgs factory with the design luminosity per collision point is about three times that of the baseline ILC running as a Higgs factory. It should be noted, however, that the upgraded ultimate ILC luminosity as a Higgs factory is four times that of the baseline. A merit of a circular collider is that multiple collisions points can be arranged. The CEPC would run with two collision points. All in all, the ILC
    as a Higgs factory is quite similar in luminosity to the CEPC. The wall plug power for the ultimate ILC Higgs factory is 187 MW, which is about the same as the current LHC, while that of CEPC is more than twice as much.

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    LC, LHC and the Chinese CEPC in overview

    At the latest LCB (Linear Collider Board) meeting, the way to communicate the physics case of the ILC to public was one of the topics intensively discussed. The LCB has then agreed that we need a short bulleted list of the physics case for the ILC. Several of us then sat down and came up with three points. Here they are with some editing:

    Important properties are the interaction strength between Higgs and other particles. ILC can measure them 3 to 10 times more accurately then the ultimate LHC. This means that the ILC is equivalent to 10 to 100 ultimate LHCs running simultaneously.

    The LHC can reach higher energy than the ILC, but can miss important phenomena.

    At the Tevatron collider, which is similar to the LHC, more than 10,000 Higgs particles were created but no clear signal was detected. At the ILC, about 100 Higgs particles are enough.

    FNAL Tevatron
    Fermilab CDF
    Fermilab DZero
    Tevatron at FNAL

    Circular electron-positron colliders have fundamental limits for energy increase due to synchrotron radiation.

    In the Standard Model of particle physics, the Higgs particle is the key particle and top quark is the heaviest particle.

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    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    Higgs-Higgs, Higgs-top interactions cannot be directly measured at the circular electron colliders since they cannot reach high enough energy. When a new particle sits at just above the energy limit, the ILC could be upgraded to reach the energy by making it longer or using higher accelerating gradient while it is difficult for a circular collider.

    See the full article here.

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    The Linear Collider Collaboration is an organisation that brings the two most likely candidates, the Compact Linear Collider Study (CLIC) and the International Liner Collider (ILC), together under one roof. Headed by former LHC Project Manager Lyn Evans, it strives to coordinate the research and development work that is being done for accelerators and detectors around the world and to take the project linear collider to the next step: a decision that it will be built, and where.

    Some 2000 scientists – particle physicists, accelerator physicists, engineers – are involved in the ILC or in CLIC, and often in both projects. They work on state-of-the-art detector technologies, new acceleration techniques, the civil engineering aspect of building a straight tunnel of at least 30 kilometres in length, a reliable cost estimate and many more aspects that projects of this scale require. The Linear Collider Collaboration ensures that synergies between the two friendly competitors are used to the maximum.

    Linear Collider Colaboration Banner

     
  • richardmitnick 12:28 pm on March 17, 2015 Permalink | Reply
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    From Symmetry: “Experiments combine to find mass of Higgs” 

    Symmetry

    March 17, 2015
    Sarah Charley

    1
    Illustration by Thomas McCauley and Lucas Taylor, CERN

    The CMS and ATLAS experiments at the Large Hadron Collider joined forces to make the most precise measurement of the mass of the Higgs boson yet.

    CERN CMS New II
    CMS

    CERN ATLAS New
    ATLAS

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    On the dawn of the Large Hadron Collider restart, the CMS and ATLAS collaborations are still gleaning valuable information from the accelerator’s first run. Today, they presented the most precise measurement to date of the Higgs boson’s mass.

    “This combined measurement will likely be the most precise measurement of the Higgs boson’s mass for at least one year,” says CMS scientist Marco Pieri of the University of California, San Diego, co-coordinator of the LHC Higgs combination group. “We will need to wait several months to get enough data from Run II to even start performing any similar analyses.”

    The mass is the only property of the Higgs boson not predicted by the Standard Model of particle physics—the theoretical framework that describes the interactions of all known particles and forces in the universe.

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    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    The mass of subatomic particles is measured in GeV, or giga-electronvolts. (A proton weighs about 1 GeV.) The CMS and ATLAS experiments measured the mass of the Higgs to be 125.09 GeV ± 0.24. This new result narrows in on the Higgs mass with more than 20 percent better precision than any previous measurements.

    Experiments at the LHC measure the Higgs by studying the particles into which it decays. This measurement used decays into two photons or four electrons or muons. The scientists used data collected from about 4000 trillion proton-proton collisions.

    By precisely pinning down the Higgs mass, scientists can accurately calculate its other properties—such as how often it decays into different types of particles. By comparing these calculations with experimental measurements, physicists can learn more about the Higgs boson and look for deviations from the theory—which could provide a window to new physics.

    “This is the first combined publication that will be submitted by the ATLAS and CMS collaborations, and there will be more in the future,” says deputy head of the ATLAS experiment Beate Heinemann, a physicist from the University of California, Berkeley, and Lawrence Berkeley National Laboratory.

    ATLAS and CMS are the two biggest Large Hadron Collider experiments and designed to measure the properties of particles like the Higgs boson and perform general searches for new physics. Their similar function allows them to cross check and verify experimental results, but it also inspires a friendly competition between the two collaborations.

    “It’s good to have competition,” Pieri says. “Competition pushes people to do better. We work faster and more efficiently because we always like to be first and have better results.”

    Normally, the two experiments maintain independence from one another to guarantee their results are not biased or influenced by the other. But with these types of precision measurements, working together and performing combined analyses has the benefit of strengthening both experiments’ results.

    “CMS and ATLAS use different detector technologies and different detailed analyses to determine the Higgs mass,” says ATLAS spokesperson Dave Charlton of the University of Birmingham. “The measurements made by the experiments are quite consistent, and we have learnt a lot by working together, which stands us in good stead for further combinations.”

    It also provided the unique opportunity for the physicists to branch out from their normal working group and learn what life is like on the other experiment.

    “I really enjoyed working with the ATLAS collaboration,” Pieri says. “We normally always interact with the same people, so it was a real pleasure to get to know better the scientists working across the building from us.”

    With this groundwork for cross-experimental collaboration laid and with the LHC restart on the horizon, physicists from both collaborations look forward to working together to increase their experimental sensitivity. This will enable them not only to make more precise measurements in the future, but also to look beyond the Standard Model into the unknown.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:20 pm on March 12, 2015 Permalink | Reply
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    From Don Lincoln at FNAL: The Detectors at the LHC 

    FNAL Home


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

    The Large Hadron Collider or LHC is the world’s biggest particle accelerator, but it can only get particles moving very quickly. To make measurements, scientists must employ particle detectors. There are four big detectors at the LHC: ALICE, ATLAS, CMS, and LHCb. In this video, Fermilab’s Dr. Don Lincoln introduces us to these detectors and gives us an idea of each one’s capabilities.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles

    CERN ALICE New II
    ALICE

    CERN ATLAS New
    ATLAS

    CERN CMS New
    CMS

    CERN LHCb New II
    LHCb

    See the full article here.

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    Fermilab Campus

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

     
  • richardmitnick 10:25 am on March 12, 2015 Permalink | Reply
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    From FNAL- “Frontier Science Result: CDF and DZero Joining forces to test the Higgs boson’s spin and parity” 

    FNAL Home


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

    Thursday, March 12, 2015
    Tom Junk

    1
    This plot shows the observed and expected upper limits at the 95 percent credibility level on the fraction of exotic boson production for two cases (spin zero with negative parity and spin two with positive parity). A signal scale of one corresponds to the Standard Model.

    The Higgs boson caused a lot of excitement when the ATLAS and CMS collaborations announced its discovery in 2012.

    CERN ATLAS New
    ATLAS

    CERN CMS New
    CMS

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

    Everyone was bursting with questions: How much does it weigh? How is it made? How does it decay? Does it have any spin, and if so, how much? Does it look the same in a mirror or not (the question of “parity”)?

    The Standard Model predicts the answers to all of these questions, although some depend on the Higgs boson mass, which ATLAS and CMS have measured precisely.

    2
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    So far, the new particle observed at the LHC is consistent with all of the Standard Model’s predictions. In particular, ATLAS and CMS’s measurements of the spin and parity allowed them to confidently identify the new particle as a Higgs boson.

    The Tevatron experiments, CDF and DZero, also found evidence for a Higgs boson in 2012, looking at events in which two bottom-flavored jets recoiled from a vector boson — either a Z or a W.

    FNALTevatron
    Tevatron

    FNAL CDF
    CDF

    FNAL DZero
    DZero

    All the same questions come up, as some models predict that one may observe a mixture of Higgs particles at the Tevatron different from what was observed at the LHC due to the different mixtures of production and decay modes that provide the most sensitivity.

    At the Tevatron, the Higgs boson’s properties were found to be consistent with those predicted for the Standard Model Higgs boson. Theorists provided a clever way to test some models of the Higgs boson’s spin and parity using Tevatron data: Higgs bosons with exotic spin and parity would be produced with more energy than the Standard Model version. CDF and DZero looked at the energies and angles of particles produced in Higgs boson events to check. But most events at the Tevatron are non-Higgs-boson background events, so a lot of hard work went in to test the models.

    Both DZero and CDF modified their Higgs boson analyses to search for the new particles, if they are present in addition to the Standard Model Higgs boson, or if they replace it entirely. Neither experiment found evidence for the exotic states, and the data prefer the Standard Model interpretation.

    But a much stronger statement can be made when CDF and DZero join forces and combine their results, using the same techniques used in the Standard Model Higgs search combinations. The signal strength of exotic Higgs bosons in the JP=0- and 2+ states is no more than 0.36 times that predicted for the Standard Model Higgs boson. Given a choice between the Standard Model Higgs boson, which has JP=0+, and one of the two exotic models replacing it with the same signal strength, the Tevatron data disfavors the exotic models with a significance of 5.0 standard deviations for 0- and 4.9 standard deviations for 2+.

    The figure above shows limits on the fraction of exotic Higgs boson production as functions of the total signal rate, assuming that the Higgs signal is a mixture of the Standard Model Higgs boson and one of the exotic kinds. The particle for which the Tevatron experiments reported evidence in 2012 is consistent with having the spin and parity predicted by the Standard Model.

    —Tom Junk

    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.

     
  • richardmitnick 4:10 pm on February 17, 2015 Permalink | Reply
    Tags: , , , , Particle Accelerators,   

    From AAAS: “Five things scientists could learn with their new, improved particle accelerator” 

    AAAS

    AAAS

    15 February
    Emily Conover

    1
    CMS

    The Large Hadron Collider (LHC) is back, and it’s better than ever.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    The particle accelerator, located at CERN, the European particle physics lab near Geneva, Switzerland, shut down in February 2013, and since then scientists have been upgrading and repairing it and its particle detectors. The LHC will be back up to full speed this May. Yesterday, scientists discussed the new prospects for the LHC at the annual meeting of AAAS (which publishes Science).

    The LHC is the world’s most powerful particle accelerator. Protons blast along its 17-mile (27-kilometer) ring at nearly light speed, colliding at the sites of several particle detectors, which sift through the resulting particle debris. In 2012, LHC’s ATLAS and CMS experiments discovered the Higgs boson with data from the LHC’s first run, thereby explaining how particles get mass.

    CERN ATLAS New
    ATLAS

    CERN CMS New
    CMS

    The revamped LHC will run at a 60% higher energy, with more sensitive detectors, and a higher collision rate. What might we find with the new-and-improved machine? Here are five questions scientists hope to answer:

    1. Does the Higgs boson hold any surprises?

    Now that we’ve found the Higgs boson, there’s still a lot we can learn from it. Thanks to the LHC’s energy boost, it will produce Higgs bosons at a rate five times higher, and scientists will be using the resulting abundance of Higgs to understand the particle in detail. How does it decay? Does it match the theoretical predictions? Anything out of the ordinary would be a boon to physicists, who are looking for evidence of new phenomena that can explain some of the unsolved mysteries of physics.

    2. What is “dark matter”?

    Only 15% of the matter in the universe is the kind we are familiar with. The rest is dark matter, which is invisible to us except for subtle hints, like its gravitational effects on the cosmos. Physicists are clamoring to know what it is. One likely dark matter culprit is a WIMP, or weakly interacting massive particle, which could show up in the LHC. Dark matter’s fingerprints could even be found on the Higgs boson, which may sometimes decay to dark matter. You can bet that scientists will be sifting through their data for any trace.

    3. Will we ever find supersymmetry?

    Supersymmetry, or SUSY, is a hugely popular theory of particle physics that would solve many unanswered questions about physics, including why the mass of the Higgs boson is lighter than naively expected—if only it were true. This theory proposes a slew of exotic elementary particles that are heavier twins of known ones, but with different spin—a type of intrinsic rotational momentum. Higher energies at the new LHC could boost the production of hypothetical supersymmetric particles called gluinos by a factor of 60, increasing the odds of finding it.

    Supersymmetry standard model
    Standard Model of Supersymmetric particles

    4. Where did all the antimatter go?

    Physicists don’t know why we exist. According to theory, after the big bang the universe was equal parts matter and antimatter, which annihilate one another when they meet. This should have eventually resulted in a lifeless universe devoid of matter. But instead, our universe is full of matter, and antimatter is rare—somehow, the balance between matter and antimatter tipped. With the upgraded LHC, experiments will be able to precisely test how matter might differ from antimatter, and how our universe came to be.

    5. What was our infant universe like?

    Just after the big bang, our universe was so hot and dense that protons and neutrons couldn’t form, and the particles that make them up—quarks and gluons—floated in a soup known as the quark-gluon plasma. To study this type of matter, the LHC produces extra-violent collisions using lead nuclei instead of protons, recreating the fireball of the primordial universe. Aided by the new LHC’s higher rate of collisions, scientists will be able to take more baby photos of our universe than ever before.

    See the full article here.

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition

     
  • richardmitnick 6:42 am on February 17, 2015 Permalink | Reply
    Tags: , , , , Particle Accelerators,   

    From CERN: “CERN accelerators boost argon into action” 

    CERN New Masthead

    16 Feb 2015
    Corinne Pralavorio

    1
    Argon ions collide with scandium in the NA61/SHINE experiment at CERN (Image: NA61)

    CERN Shine
    SPS
    The experiment is located in the North Area of CERN and the particles are accelerated by SPS

    CERN’s accelerators supply a raft of experiments with all sorts of different particles. Now the accelerator complex is performing a new trick: supplying argon ions to an experimental programme for the first time. The argon ions are produced at a special source and made to circulate around four accelerators before being sent to a target.

    Preparations for this beam of argon ions have been in progress at the CERN accelerator chain for two years. Controlling these particles, which have a much greater mass than protons and are sent at six different energies, is no mean feat. The machine operators had to adapt the acceleration system of the Super Proton Synchrotron (SPS), a 7-kilometre-circumference accelerator that represents the last loop on the ions’ journey before they are ejected.

    The SPS is the last accelerator in the chain before the 27-kilometre-circumference Large Hadron Collider (LHC). To allow eight weeks of physics with argon ions while also sending protons to the LHC experiments, the accelerators will alternate between these two types of particles. In each cycle of 21.6 seconds, the SPS will deliver two beams of protons and one beam of argon ions.

    The argon ions are destined for the NA61/Shine experiment, which is studying the phenomenon of quark-gluon plasma, a state that is thought to have existed at the very beginning of the universe and in which quarks moved around freely, unconfined by the strong force in protons and neutrons. More specifically, the experiment is studying the transitions between the phase in which quarks are confined and the phase in which they are free. Last Thursday, the NA61/SHINE team recorded first collisions with argon: the argon ions, travelling with a momentum of 150 GeV/c per nucleon, collided with scandium nuclei.

    CERN’s accelerators accelerate protons most of the time, but occasionally juggle with other particles. Aside from lead ions and now argon ions, the complex has also accelerated electrons, positrons, antiprotons, deuterons and a particles, as well as oxygen, sulphur and indium ions. These particles are either collided with each other or sent to targets to create beams of secondary particles, such as neutrinos. The accelerator complex supplies around twenty experiments studying a wide range of physics phenomena, such as antimatter, exotic nuclei, neutrinos, cosmic rays, the strong interaction and the Higgs boson. Some are looking for signs of physics beyond the current theories or for as yet unknown particles that might help to account for dark matter. They include the four main LHC experiments ALICE, ATLAS, CMS and LHCb, which are the best known and which will be back in action as of the spring. In addition, several dozen experiments are carried out each year at the ISOLDE and n_TOF nuclear physics facilities.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New

    LHC particles

    Quantum Diaries

     
  • richardmitnick 6:54 am on February 15, 2015 Permalink | Reply
    Tags: , ATLAS Canada, , , Particle Accelerators,   

    From TRIUMF Lab: “ATLAS-Canada Prepares for Next Run of the Large Hadron Collider; Higher Intensity Predicted to Generate More Data” 

    WestGrid Canada
    Compute Calcul Canada

    Feb 15, 2015

    Reda Tafirout
    ATLAS-Canada, TRIUMF

    1
    The eight torodial magnets can be seen on the huge ATLAS detector with the calorimeter before it is moved into the middle of the detector. This calorimeter will measure the energies of particles produced when protons collide in the centre of the detector. ATLAS will work along side the CMS experiment to search for new physics at the 14 TeV level. Image Courtesy of CERN.

    CERN CMS New
    CMS

    In March 2015, the world’s largest particle accelerator, the Large Hadron Collider (LHC), will end a two-year shutdown and begin its second running phase, this time at a significantly higher collision energy level than before.

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

    Run 2, which will last three years, will restart at a record collision energy of 13 TeV, nearly double the beam intensity of the LHC’s initial running phase (2010-2013). One electron volt, or 1 eV is the energy generated from a single electron moving through a potential of 1 Volt. With the doubling of the LHC collision energy, the potential exists for new opportunities to find physics beyond the Standard Model and to broaden the Higgs physics program.

    2
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    ATLAS-Canada, a partner in the international ATLAS experiment, has worked with Compute Canada since its inception to fully integrate Compute Canada computing facilities into the Worldwide LHC Computing Grid (WLCG). Since 2011, Compute Canada resource allocations have been instrumental in supporting ATLAS scientists’ work, including their major and historical discovery of a Higgs particle in July 2012.

    This January, ATLAS-Canada was one of a handful of research groups in the country who received an allocation through Compute Canada’s inaugural RPP competition. In 2015, ATLAS Canada will have access to 3,378 core years of computational power and 3,164 TB of storage capacity on Compute Canada systems. This storage allication is expected to nearly double in 2017.

    “The availability of Compute Canada resources is crucial to our continued contribution to the groundbreaking discoveries coming from the Large Hadron Collider,” says Reda Tafirout, a TRIUMF Research Scientist and ATLAS-Canada Computing Coordinator. “The computational needs for 2015-2017 remain very high as a much larger volume of data will be collected and generated during LHC Run 2 phase. The proton-proton collisions will occur at a much higher beam energy and intensity making analysis more complex. Significant computing resources will be required to analyze the data and to produce large-scale simulation samples in a timely fashion.”

    Each year, the ATLAS experiment collects several Petabytes of raw data during LHC operations, and it produces numerous derived and simulated datasets that are of similar scale effectively on a continuous basis. The nature of ATLAS computing and its scale require the resources to be distributed across multiple sites so productivity does not come to a halt for a sustained period during either a scheduled maintenance, site expansion/consolidation, or other issues such as a security breach or service vulnerability.

    As part of WLCG, there are two ATLAS Tier-2 federations based at Compute Canada facilities: one in the east and one in the west. SciNet (University of Toronto) and CLUMEQ (McGill University) facilities are used in the east, while in the west, WestGrid facilities at Simon Fraser University and the University of Victoria are used. Distributing Compute Canada resources for ATLAS across a few sites allows load balancing across sites and also leverages the knowledge accumulatedby the local technical experts.

    “These resources allow us to meet our increasing commitments to ATLAS as more data are being generated, and allows Canadians to remain competitive on the world stage,” says Tafirout.

    One of the priorities of the LHC Run 2 physics program is to determine whether the new boson discovered in 2012 is precisely the Higgs boson of the Standard Model, or possibly the lightest boson of several in an extended Higgs sector.

    In addition, Canadian scientists will continue to lead a number of other important research investigations at ATLAS. These include the search for quantum black holes and strong gravity effects; the search for massive long-lived highly ionizing particle or a particle with a large electric charge; leading several important measurements in various collision event topologies and models; and preparing to measure the scattering of two massive vector bosons (VBS), which is a key process to probe the nature of electroweak symmetry breaking and allows to test if the Higgs sector is fully responsible to unitarize this amplitude.

    “The coming years will provide access to the design energy and increased luminosity of the LHC and therefore mark a crucial time in the search for new physics,” says Tafirout. “The extra Canadian-only computing resources will have a high impact and will keep Canadians highly competitive in these exciting times for particle physics.”

    Presently, the ATLAS-Canada collaboration consists of 39 faculty members at nine universities (plus ATLAS TRIUMF, Canada’s National Laboratory for Particle and Nuclear Physics), as well as 25 postdoctoral fellows, and 66 graduate students. This represents about half of the experimental particle physics community in Canada. The Canadian universities are University of Alberta, University of British Columbia, Carleton University, McGill University, Université de Montréal, Simon Fraser University, University of Toronto, University of Victoria, and York University. The overall ATLAS collaboration consists of about 3,000 researchers from 177 institutions in 38 countries (see http://atlas.ch).

    “The next three years will be very exciting for the ATLAS collaboration and it is important for Canada to remain a key player and contributor to the scientific output of the ATLAS experiment,” says Tafirout. “Canadians plan to build on the expertise and leadership that they demonstrated during Run 1 and are well equipped to make key contributions to ATLAS during Run 2.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Triumf Campus
    Triumf Campus
    World Class Science at Triumf Lab, British Columbia, Canada
    Canada’s national laboratory for particle and nuclear physics
    Member Universities:
    University of Alberta, University of British Columbia, Carleton University, University of Guelph, University of Manitoba, Université de Montréal, Simon Fraser University,
    Queen’s University, University of Toronto, University of Victoria, York University. Not too shabby, eh?

    Associate Members:
    University of Calgary, McMaster University, University of Northern British Columbia, University of Regina, Saint Mary’s University, University of Winnipeg, How bad is that !!

     
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