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  • richardmitnick 7:33 pm on September 21, 2014 Permalink | Reply
    Tags: , , , , High Energy Physics, ,   

    From BBC: “‘Artificial retina’ could detect sub-atomic particles” 

    BBC

    18 September 2014
    Melissa Hogenboom

    The human eye has inspired physicists to create a processor that can analyse sub-atomic particle collisions 400 times faster than currently possible.

    In these collisions, protons – ordinary matter – are smashed together at close to light speeds.

    pro
    The quark structure of the proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons

    These powerful smash-ups could yield new particles and help scientists understand matter’s mirror, antimatter.

    anti
    The quark structure of the antiproton

    The experimental processor could speed up the analysis of data from the collisions.

    Published in the pre-print arXiv server, the algorithm has been proposed for possible use in Large Hadron Collider (LHC) experiments at Cern in 2020. It could also be useful in any field where fast, efficient pattern recognition capabilities are needed.

    CERN LHC Grand Tunnel
    LHC

    The processor works in a similar way to the retina’s incredible ability to recognise patterns extremely quickly.
    Snapshots in time

    That is, individual neurons in our retinas are specialised to respond to particular shapes or orientations, which they do automatically before our brain is even consciously aware of what we are processing.

    pd
    Image of particle decay LHC machines produce 40 million collisions per second

    Cern physicist Diego Tonelli, one of a team of collaborators of the work, explained that the “artificial retina” detects a snapshot of the trajectory of each collision which is then immediately analysed.

    These snapshots are then mapped into an algorithm that can run on a computer, automatically scanning and analysing the charged particle trajectories, or tracks. Exposing the detector to future collisions will then allow teams sift out the interesting events.

    Data crunching

    Speed is of the essence here. There are roughly 40 million collisions per second and each can result in hundreds of charged particles.

    The scientists then have to plough through an incredible amount of data. It’s spotting the deviations from the norm that may give hints of new physics.

    lhcb
    LHCb experiment
    The LHC will be switched on again in early 2015

    An algorithm like this could therefore provide a useful way of crunching through this vast amount of data, in real time.

    “It’s 400 times faster than anything existing or foreseen for high energy physics applications. If implemented in a real experiment it will allow us to collect more interesting data more quickly,” Dr Tonelli told the BBC.

    Flavour physics

    The LHC has been switched off since February 2013 but is due to begin its hunt for new physics in 2015 when the giant machine will once again begin smashing together protons.

    As this happens, they break down and free up a huge amounts of energy that forms many neutral and charged particles. It’s the trajectories of the charged ones that can be observed.

    col
    Particle collisions
    A collision in the Large Hadron Collider creates tracks of charged particles

    The new algorithm is not aimed at the type of physics used to find the famous Higgs boson, instead it’s intended to be used for “flavour physics” which deals with the interaction of the basic components of matter, the quarks.

    Commenting on the work, Tara Shears a Cern particle physicist from the University of Liverpool, said it could be extremely useful to automatically “give us most information about what we want to study – Higgs, dark matter, antimatter and so on. The artificial retina algorithm looks like it does this brilliantly”.

    “When our detectors take these snapshots of the collisions – to us that’s like the picture that your eye sees and when your brain is scanning that picture and making sense of it, well we try and codify those rules into an algorithm that we run on computers that do the job for us automatically,” Prof Shears told the BBC’s Inside Science programme.

    “When the LHC continues… we will start to operate with a more intense beam of protons getting a much higher data rate, and then this problem of sifting out what you really want to study becomes really really pressing,” she added.

    “This artificial retinal algorithm is one of the latest steps in our mission to [understand the Universe], and it’s really good, it does the job vast banks of computers normally do.”

    The algorithm has been developed with the 2020 upgrade of the LHC in mind, which will have even more powerful collisions.

    See the full article here.

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  • richardmitnick 7:04 pm on September 21, 2014 Permalink | Reply
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    From physicsworld: “A day in the life of CERN’s director-general” 

    physicsworld
    physicsworld.com

    Sep 16, 2014
    By Rolf-Dieter Heuer, Geneva

    There is no such thing as a typical day in the life of a CERN director-general (DG), certainly not this one in any case. In my experience, each incumbent has carved out a slightly different role for themself, shaped by the laboratory’s priorities and activities at the time of their mandate. For me, every day goes beyond science, management and administration, and I am particularly fortunate to have been DG through a remarkable period that has seen not only the successful launch of the Large Hadron Collider (LHC) and confirmation of the Brout–Englert–Higgs mechanism, but also an opening of CERN to the world – an area that I have pursued with particular vigour.

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

    dg
    All in a day’s work. (Courtesy: CERN)

    As I regularly joke, we have changed the “E” of CERN from “Europe” to “Everywhere”, and that has meant a lot of travel for the CERN DG, as we hold discussions with prospective new members of the CERN family. And when the CERN Council opened up membership to countries from beyond the European region in 2010, it seemed to me that we should also be extending our contacts in other directions as well.

    For that reason, I have taken up the CERN DG’s standing invitation to attend the World Economic Forum’s annual meeting in Davos, where I strive to get science further up the agenda, and I have actively pursued a policy of engagement with other international organizations. CERN’s host city is home to a concentration of international organizations like nowhere else on Earth, and our missions overlap in areas ranging from technology to standards to intellectual property. A typical day might see me paying a visit to the United Nations Office in Geneva, or receiving a visit from the ambassador of an existing or prospective CERN member state.

    But the role goes beyond one of diplomacy. The CERN DG has, first and foremost, a lab to run. Although I have a strong team of directors and department leaders to help me, issues ranging from liaison between experiments to delicate issues in human resources or dealings with officials from our two host states – France and Switzerland – find their way to my door. Each year is punctuated by fixed points for the meetings of advisory and governance bodies, for directorate meetings and presentations to personnel.

    With all this going on, there is no typical day, so I’ll describe the most untypical of all during my term of office: Wednesday 4 July 2012.

    I’d been told that people were so keen to have a seat in CERN’s main auditorium for that day’s Higgs-update seminar that some were prepared to camp out all night to secure their place, so I came in early to see if it were true. I expected to see a few hardy souls at 7 a.m., but not the long snaking queue, headed up by sleeping bags, that started outside the doors of the auditorium, carried on all the way along corridors and ended up down the stairs in main entrance lobby. The atmosphere was reserved, yet excited, with an air of expectation about it. I went up to my office to prepare my notes and gather my thoughts.

    We had not known until the last minute whether or not we would be announcing a discovery or just another step on the way. Yet the world was expectant. Peter Higgs and François Englert were at CERN, as were Gerry Guralnik and Carl Hagen – two of the three authors of the other pioneering paper from the 1960s that had anticipated what we now know as the Brout–Englert–Higgs mechanism. Robert Brout, unfortunately, did not live to see the confirmation of his ideas, while Tom Kibble – Guralnik and Hagen’s co-author – was at a parallel event in London. The press were also there in force, and the CERN Council’s meeting room was converted into a media centre for the day.

    Although just a few days earlier I didn’t know what message I’d be bringing to the expectant crowd, at 7 a.m. that day I had what I needed to announce a discovery. Over the preceding weeks and days, Fabiola Gianotti and Joe Incandela had each kept me up to date with the status of the analyses from the ATLAS and CMS experiments of which they were the spokespersons, and by the Friday before the seminar, I’d seen enough. Although by that time neither experiment was sure they’d be able to announce the required 5σ significance needed to claim discovery, I’d seen both experiment’s results, and that was enough for me to know that taken together the 5σ would be reached.

    CERN ATLAS New
    ATLAS

    CERN CMS New
    CMS

    rdh
    Wednesday 4 July 2012 was an extraordinary day. (Courtesy: CERN)

    By the time I went back down to the auditorium, the doors had been opened and people had taken their seats, yet the crowd outside seemed even bigger than before. Inside the room, the mood was an unusual mixture of party and scientific seminar. We were being watched around the world: nearly half a million people tuned in to the webcast, I’m told, and we had a room full of physicists in Melbourne assembled there on the eve of that year’s major particle-physics conference, beamed to a screen above my head. It culminated in joyous scenes as the experiments announced their results: as it turned out, they didn’t need me to announce the discovery. Peter Higgs, sitting next to François Englert whom he’d met for the first time that day, had a smile on his face that said it all.

    The seminar was over, but for me the day was just beginning. Fabiola, Joe and I were ushered into the media centre for a press conference, in which the theorists were given a front-row seat. Once the media scrum has subsided and Peter Higgs had graciously led the theorists in saying that this was a day for the experiments and there’d be time to talk to him later, the three of us recounted the story all over again before spending the day giving interview after interview.

    Eventually, the cameras stopped clicking, the microphones were put back in their bags, and it was time to head off for the airport to catch my flight to Melbourne for the conference. It was only when I got on the plane and ordered a glass of champagne that the enormity of the day sunk in. It had been an incredible day, full of emotion, leaving me happy not only with the result, but also with that fact that it had so strongly captured the world’s imagination.

    A day in the life of the CERN DG? Always challenging, sometimes exhausting, frequently frustrating but always rewarding. And although 4 July 2012 may not have been a typical day, it is for me one of the most memorable of all.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

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  • richardmitnick 11:09 am on September 21, 2014 Permalink | Reply
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    From The Daily Galaxy: “”Hidden Supersymmetry?” –Debate Over a New Physics Intensifies (The Weekend Feature)” 

    Daily Galaxy
    The Daily Galaxy

    Theoretical physicists have theorized a possible solution to a longstanding mystery bolstered by the recent discovery of the Higgs boson – a way to preserve the theory of supersymmetry. It was a breakthrough with profound implications for the world as we know it: the Higgs boson, the elementary particle that gives all other particles their mass, discovered at the Large Hadron Collider in 2012. But, for many scientists, it’s only the beginning. When the LHC fires up again in 2015 at its highest-ever collision energy, theorists will be watching with intense interest.
    Earlier this year in Physical Review Letters, Csaba Csaki, Cornell professor of physics, and colleagues theorized a possible solution to a longstanding mystery bolstered by the recent discovery of the Higgs – a way to preserve the theory of supersymmetry, a popular, but experimentally unproven, extension of the Standard Model of particle physics.

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

    higgs
    Depiction of Higgs Boson

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC

    image

    Supersymmetry could help explain the unusual properties of the Higgs boson, why the strong and weak interactions of subatomic particles appear to be so different, as well as the origin of dark matter, which makes up a quarter of the universe.

    The Standard Model deals with three of nature’s fundamental forces: strong, weak and electromagnetic, which govern the relationships between all the known subatomic particles. Supersymmetry extends the Standard Model by introducing new particles, called “superpartners”; every observed particle would have a corresponding superpartner, with similar properties to those of the observed particles, except heavier and with different spin values.

    Some scientists think supersymmetry ought to be abandoned after the LHC failed to detect any of these superpartners; some of them, like the top quark’s superpartner, the “stop,” is predicted to be so light that the LHC should already have seen it.

    In their paper, Csaki and colleagues counter that the particles may be hidden by the noise of other particles formed during the LHC’s unprecedented energy of proton-proton collisions.

    Their idea has to do with a concept called R-parity. All observed particles are assumed to have positive R-parity, while the unobserved superpartners would be negative, implying that the superpartners cannot decay to ordinary particles exclusively.

    Searching for the superpartners at the LHC, Csaki explained, has largely operated under the assumption that this R-parity is always exactly conserved. Csaki and colleagues pose a scenario in which R-parity is violated, and would result in a series of interactions giving rise to particle decays that would be nearly impossible to detect by the LHC’s current parameters.

    “The upshot is that there are ways to hide supersymmetry at the LHC,” Csaki said. “If the signal isn’t very different from the background, it’s very hard to find them. That’s the problem.”

    The LHC, when back online next year, is scheduled to run at a collision energy of 14 TeV (teraelectron volts) – about double the energy of previous runs. It could lead to ultimate proof of the theory of supersymmetry, which Csaki deems the “most beautiful” of the Standard Model extensions offered today – but science must make room for all possibilities.

    “It’s very possible that supersymmetry is not the right theory, and that’s OK,” he said. “The important thing is to understand the way science works, to try and make the best guesses you can, and the experimentalists go and check it. … We have to make sure we are exploring every corner, and we shouldn’t leave some potentially reasonable theory out where things could be hiding.”

    The image at the top of the page is an artist’s simulation of dark matter halo around the Milky Way galaxy.’s own backyard. Credit: NASA, ESA, and T. Brown and J. Tumlinson (STScI)

    See the full article here.

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  • richardmitnick 12:34 pm on September 19, 2014 Permalink | Reply
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    From Fermilab- “Frontier Science Result: CMS Three ways to be invisible” 


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

    Friday, Sept. 19, 2014
    Jim Pivarski

    There is a common misconception that the LHC was built only to search for the Higgs boson. It is intended to answer many different questions about subatomic particles and the nature of our universe, so the collision data are reused by thousands of scientists, each studying their own favorite questions. Usually, a single analysis only answers one question, but recently, one CMS analysis addressed three different new physics: dark matter, extra dimensions and unparticles.

    CERN CMS New
    CMS

    CERN LHC Grand Tunnel
    CERN LHC Map
    CERN LHC particles
    LHC

    The study focused on proton collisions that resulted in a single jet of particles and nothing else. This can only happen if some of the collision products are invisible — for instance, one proton may emit a jet before collision and the collision itself produces only invisible particles. The jet is needed to be sure that a collision took place, but the real interest is in the invisible part.

    proton
    The quark structure of the proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons

    Sometimes, the reason that nothing else was seen in the detector is mundane. Particles may be lost because their trajectories missed the active area of the detector or a component of the detector was malfunctioning during the event. More often, the reason is due to known physics: 20 percent of Z bosons decay into invisible neutrinos. If there were an excess of invisible events, more than predicted by the Standard Model, these extra events would be evidence of new phenomena.

    The classic scenario involving invisible particles is dark matter. Dark matter has been observed through its gravitational effects on galaxies and the expansion of the universe, but it has never been detected in the laboratory. Speculations about the nature of dark matter abound, but it will remain mysterious until its properties can be studied experimentally.

    Another way to get invisible particles is through extra dimensions. If our universe has more than three spatial dimensions (with only femtometers of “breathing room” in the other dimensions), then the LHC could produce gravitons that spin around the extra dimensions. Gravitons interact very weakly with ordinary matter, so they would appear to be invisible.

    A third possibility is that there is a new form of matter that isn’t made of indivisible particles. These so-called unparticles can be produced in batches of 1½ , 2¾ , or any other amount. Unparticles, if they exist, would also interact weakly with matter.

    All three scenarios produce something invisible, so if the CMS data had revealed an excess of invisible events, any one of the scenarios could have been responsible. Follow-up studies would have been needed to determine which one it was. As it turned out, however, there was no excess of invisible events, so the measurement constrains all three models at once. Three down in one blow!

    LHC scientists are eager to see what the higher collision energy of Run 2 will deliver.

    See the full article here.

    Fermilab Campus

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

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  • richardmitnick 3:30 pm on September 18, 2014 Permalink | Reply
    Tags: , High Energy Physics,   

    From LC Newsline- “ILC: What’s happening in Japan” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    18 September 2014
    Lyn Evans

    In September 2013, the Science Council of Japan (SCJ) published a report on the ILC. This report contains two key statements and requests.

    Concerning the scientific justification for the ILC:

    “The Committee appreciates that the ILC enables the precision measurements of the detailed properties of the Higgs particle and the top quark, thereby exploring the physics beyond the Standard Model of particle physics and, therefore, it acknowledges that the ILC is endowed with the scientific value in particle physics. The Committee, however, expresses the desire for more compelling and articulate argument to justify the ILC project in order to search for unknown particles and the physics beyond the Standard Model, running concurrently with the upgraded LHC, given the considerable investment it will require.”

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

    Concerning the project cost:

    “Before making the final decision of whether the ILC should be hosted in Japan, the issues and concerns described in this document should be fully investigated and a clear vision for solutions needs to be provided. They include the whole profile of project cost for the construction, operation, upgrades and decommissioning, as well as prospect for cost-sharing among the countries involved. Also included are the issues related to human resources and management/operation organization.”

    In response, the Ministry of Education, Sports, Science and Technology (MEXT) set up a “Task force for ILC” under the vice-Minister, which itself set up an “Academic Experts Committee” which first met in May 2014. At that meeting the committee formed two working groups in order to respond to the two key requests of the SCJ.

    In order to address the scientific issues a “Particle and Nuclear Physics Working Group” led by Takaaki Kajita (Director of the Institute for Cosmic Ray Research, University of Tokyo) was formed. The timetable and subjects for meetings of this Working Group as known so far is as follows:

    24 June 2014: Status of Particle Physics and ILC physics overview.

    29 July 2014: Future prospects in the US and Europe

    27 August 2014: Cosmic ray and Astrophysics and ILC.

    22 September 2014: Flavour and neutrino physics and ILC

    21 October 2014: Interim summary to be reported to Experts Committee.

    In order to address technical issues, a “Technical Design Report Validation” Working Group has been formed under the leadership of Hideaki Yokomizo (Former Trustee of JAEA). The first open meeting of this working group was held on 30 June 2014, giving an overview. Further working group meetings are in progress for detailed discussions on the TDR contents with cost-estimates in closed sessions.

    Information is being fed to this working group through the ILC Planning Office at KEK after verification by the LCC. Note that at the present time, this is a purely internal Japanese process. All committee and working group members are Japanese and no input is requested from outside Japan except indirectly through the LCC so far.

    In addition to setting up this Committee and its Working Groups, on 19 August MEXT published a Call for Tender for a survey:

    “Research, survey and analysis on technology spinoffs and subsequent economic ripple effects expected from the International Linear Collider (ILC) project and the global trend of the particle/nuclear physics research including technology R&D.”

    This survey will be conducted by a private company, yet to be chosen, and should be completed by the end of March 2015. It is expected that this company will consult with the major laboratories world-wide.

    I hope that the upcoming LCWS14 workshop in Belgrade will help refine the scientific arguments and differentiate the International Linear Collider from the other proposed lepton colliders and help our Japanese colleagues to feed correct and compelling arguments to the working groups.

    See the full article here.

    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

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  • richardmitnick 3:10 pm on September 18, 2014 Permalink | Reply
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    From Symmetry: “Pursuit of dark matter progresses at AMS” 

    Symmetry

    September 18, 2014
    Kathryn Jepsen

    A possible sign of dark matter will eventually become clear, according to promising signs from the Alpha Magnetic Spectrometer experiment.

    NASA AMS02 Banner

    NASA AMS02 device
    AMS Device

    New results from the Alpha Magnetic Spectrometer experiment show that a possible sign of dark matter is within scientists’ reach.

    Dark matter is a form of matter that neither emits nor absorbs light. Scientists think it is about five times as prevalent as regular matter, but so far have observed it only indirectly.

    The AMS experiment, which is secured to the side of the International Space Station 250 miles above Earth, studies cosmic rays, high-energy particles in space. A small fraction of these particles may have their origin in the collisions of dark matter particles that permeate our galaxy. Thus it may be possible that dark matter can be detected through measurements of cosmic rays.

    AMS scientists—based at the AMS control center at CERN research center in Europe and at collaborating institutions worldwide—compare the amount of matter and antimatter cosmic rays of different energies their detector picks up in space. AMS has collected information about 54 billion cosmic ray events, of which scientists have analyzed 41 billion.

    Theorists predict that at higher and higher energies, the proportion of antimatter particles called positrons should drop in comparison to the proportion of electrons. AMS found this to be true.

    However, in 2013 it also found that beyond a certain energy—8 billion electronvolts [BeV]—the proportion of positrons begins to climb steeply.

    “This means there’s something new there,” says AMS leader and Nobel Laureate Sam Ting of the Massachusetts Institute of Technology and CERN. “It’s totally unexpected.”

    The excess was a clear sign of an additional source of positrons. That source might be an astronomical object we already know about, such as a pulsar. But the positrons could also be produced in collisions of particles of dark matter.

    Today, Ting announced AMS had discovered the other end of this uptick in positrons—an indication that the experiment will eventually be able to discern what likely caused it.

    “Scientists have been measuring this ratio since 1964,” says Jim Siegrist, associate director of the US Department of Energy’s Office of High-Energy Physics, which funded the construction of AMS. “This is the first time anyone has observed this turning point.”

    The AMS experiment found that the proportion of positrons begins to drop off again at around 275 billion electronvolts.

    The energy that comes out of a particle collision must be equal to the amount that goes into it, and mass is related to energy. The energies of positrons made in dark matter particle collisions would therefore be limited by the mass of dark matter particles. If dark matter particles of a certain mass are responsible for the excess positrons, those extra positrons should drop off rather suddenly at an energy corresponding to the dark matter particle mass.

    If the numbers of positrons at higher energies do decrease suddenly, the rate at which they do it can give scientists more clues as to what kind of particles caused the increase in the first place. “Different particles give you different curves,” Ting says. “With more statistics in a few years, we will know how quickly it goes down.”

    If they decrease gradually instead, it is more likely they were produced by something else, such as pulsars.

    To gain a clearer picture, AMS scientists have begun to collect data about another matter-antimatter pair—protons and antiprotons—which pulsars do not produce.

    p
    The quark structure of the proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

    ap
    The quark structure of the antiproton.

    The 7.5-ton AMS experiment was able to make these unprecedented measurements due to its location on the International Space Station, above the interference of Earth’s atmosphere.

    “It’s really profound to me, the fact that we’re getting this fundamental data,” says NASA Chief Scientist Ellen Stofan, who recently visited the AMS control center. “Once we understand it, it could change how we see the universe.”

    AMS scientists also announced today that the way that the positrons increased within the area of interest, between 8 and 257 GeV, was steady, with no sudden peaks. Such jolts could have indicated the cause of the positron proliferation were sources other than, or in addition to, dark matter.

    In addition, AMS discovered that positrons and electrons act very differently at different energies, but that, when combined, the fluxes of the two together unexpectedly seem to fit into a single, straight slope.

    “This just shows how little we know about space,” Ting says.

    Fifteen countries from Europe, Asia and America participated in the construction of AMS. The collaboration works closely with a management team at NASA’s Johnson Space Center. NASA carried AMS to the International Space Station on the final mission of the space shuttle Endeavour in 2011.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 10:50 am on September 16, 2014 Permalink | Reply
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    From New Scientist: “Curtain closing on Higgs boson photon soap opera” 

    NewScientist

    New Scientist

    15 September 2014
    Michael Slezak

    It was the daytime soap opera of particle physics. But the final episode of the first season ends in an anticlimax. The Higgs boson‘s decay into pairs of photons – the strongest yet most confusing clue to the particle’s existence – is looking utterly normal after all.

    Experiments don’t detect the Higgs boson directly – instead, its existence is inferred by looking at the particles left behind when it decays. One way it made itself known at CERN’s Large Hadron Collider near Geneva, Switzerland, two years ago was by decaying into pairs of photons. Right at the start, there were so many photons that physicists considered it a “deviant decay” – and a possible window into new laws of physics, which could help explain the mysteries of dark energy and the like.

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

    Even as other kinks in the data got ironed out, the excess of photons remained. At the time, physicists speculated that it could be due to a mysterious second Higgs boson being created, or maybe the supersymmetric partner of the top quark.

    Supersymmetry standard model
    Standard Model showing Supersymmetric Particles

    Identity crisis

    If unheard of particles and physical laws weren’t dramatic enough, six months later, the decay into photons was giving the Higgs an identity crisis. When physicists measured the Higgs mass by observing it decaying into another type of particle, called a Z boson, it appeared lighter than when doing a similar calculation using the decay into photons. “The results are barely consistent,” Albert de Roeck, one of the key Higgs hunters at CERN’s CMS experiment, said at the time.

    But over the past year, physicists at CERN have found that the Higgs boson is acting exactly as the incomplete standard model of particle physics predicts, leaving us with no clues about how to extend it.

    Now, in an anticlimactic summary on the two photon decay, both big experiments at the LHC have posted results showing the photons are, after all the fuss, also doing exactly what the standard model predicts.

    Powering up

    “This is probably the final word,” wrote CERN physicist Adam Falkowski on his blog.

    Ever the optimist, de Roeck thinks there’s still room in the data for the two photon decay channel to be caught misbehaving. Our present outlook is due to our relatively fuzzy view of the behaviour so far, he says. When the LHC is switched back on next year after an upgrade, it will be smashing protons together with double the previous energy.

    With that kind of power, the measurements will be more exact, and any small deviations from standard model predictions could emerge. “It is most likely the last word for run one of the LHC, but definitely not the last word,” de Roeck says. “I still believe ultimately we will find significant deviations or something unexpected in the Higgs sector. Then all hell will break loose.”

    See the full article here.

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  • richardmitnick 4:04 pm on September 7, 2014 Permalink | Reply
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    From Don Lincoln for JHU Press: “Damage to the Large Hadron Collider” 

    jhu

    FNAL Don Lincoln
    FNAL’s Dr. Don Lincoln

    September 5, 2014

    A spark. That’s all it was . . . just a little spark . . . in a vacuum, no less. It sounds so harmless. What could it hurt? Let’s see how the story unfolds.

    Well, time, which is measured in microseconds at this point, moved on. The spark jumped from copper conductor to copper conductor, causing copper atoms to be knocked off into the vacuum. As the amount of copper vapor grew, the vacuum became less of an insulator and more conductive, letting more electricity flow. That’s when things began to get interesting. Like opening a faucet completely, the trickle of the initial spark grew until it became a torrent of electricity: ten thousand amperes, enough to simultaneously start thirty or so cars in the dead of winter. The onslaught of electricity was enough to melt a chunk of copper the size an adult fist. This would be bad, but, if you will excuse the pun, things were just beginning to heat up.

    The tipping point from annoying incident to serious disaster occurred when the heat from the electrical arc punctured the volume filled with the liquid helium used to cool the Large Hadron Collider magnets to more than 450° Farenheit below zero. Luckily, helium is an inert gas, so an explosion in the usual sense of the word was impossible. However, the helium was in liquid form, and when it encountered more ordinary temperatures, it boiled and turned into gas. When any liquid turns to gas at atmospheric temperature, it expands in volume to 700 times its ordinary size. And the LHC magnets contain an awful lot of helium . . . as in 96 tons of helium. (Although, in the end, only six tons were released.)

    As the helium vented from the storage volume, it jetted out with tremendous force. And by “tremendous force,” I mean enough force to move a 50-foot-long magnet weighing 35 tons and anchored to the concrete floor about two feet. As the helium gas expanded in the LHC tunnel, it pushed air out of the way. The boundary between an environment containing ordinary air and one containing only helium moved up the tunnel at incredible speed. It was possible for a human to outrun the helium monster, but only if the person could run a four-minute mile. Run any slower, and you would be overtaken by helium. Soon, you would fall down and die, suffocated by lack of oxygen.

    Luckily, there was nobody near the punctured helium volume to be in danger. Actually, luck had nothing to do with it. The CERN (European Organization for Nuclear Research) safety professionals were aware of the danger of a catastrophic failure. Although such an incident was extremely unlikely, people are allowed in the Large Hadron Collider tunnel only rarely. If they are allowed inside, they must have special training and carry oxygen tanks and protective clothing. In this case, however, the nearest CERN personnel were miles away from the incident, and even the civilians who lived above the LHC were separated by at least 300 feet of solid rock. No people were ever in danger.

    I was in the United States on the day in September 2008 when the LHC broke. My colleagues and I were getting reports second-hand, and I remember well the group sitting around a table, looking shell-shocked, and asking each other, “How bad can it be?”

    So now, in the fullness of time, we can answer that question. How bad was it? Pretty bad. Repairing the LHC cost tens of millions of dollars and took about a year. In the end, fifty-three magnets, each fifty feet long and weighing thirty-five tons, needed to be removed, repaired, cleaned, and replaced. While the true damage was relatively localized, among the collateral damage was a breeching of the LHC’s beam pipe, into which soot and debris spread for a mile or so. The technicians were busy.

    It is now six years later, and perhaps it is time for a broader viewpoint. Yes, the damage was grave, and yes, it took a year to repair. However, the repair costs were about two percent the cost of the entire LHC, and the delay was only about five percent of the schedule. Granted, if you were a graduate student who was hoping to graduate on the first year’s data, the incident was an awful delay. However, now, in 2014, what was the real consequence? Well, we now have an accelerator that is better instrumented against similar incidents. The damage of 2008 won’t occur again. We have studied billions of particle collisions and begun to explore the behavior of matter under conditions never before possible. We have discovered the Higgs boson and facilitated a Nobel Prize in physics. There have been some considerable successes, and the debacle of 2008 is now fading into distant memory.

    It’s all a matter of perspective. And, let us not forget, the data of 2015 beckons alluringly. Soon the universe will give up some more of her mysteries and scientists will do what they have for millennia: they will take up their pens and begin writing a new page in the book of knowledge, a book whose first pages were penned over two thousand years ago.

    Perspective.

    Don Lincoln is a senior scientist at Fermi National Accelerator Laboratory and an adjunct professor of physics at the University of Notre Dame. He is the author of

    The Large Hadron Collider: The Extraordinary Story of the Higgs Boson and Other Stuff That Will Blow Your Mind
    book

    , Alien Universe: Extraterrestrials in Our Minds and in the Cosmos
    book3

    and The Quantum Frontier: The Large Hadron Collider,
    book2

    all published by Johns Hopkins.

    See the full article here.

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  • richardmitnick 10:41 am on September 4, 2014 Permalink | Reply
    Tags: , , , High Energy Physics, ,   

    From FNAL- “Frontier Science Result: CDF The final word on Z’s and jets from CDF” 


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

    Thursday, Sept. 4, 2014
    edited by Andy Beretvas

    charts
    Inclusive jet pT differential cross sections for Z + one or more jet events. The measured differential cross section (black dots) is compared to the LOOPSIM + MCFM prediction (open circle). On the right many other theoretical predictions are shown.

    Our understanding of the strong force, called QCD (quantum chromodynamics) is very advanced. This theory describes the interactions between some of nature’s fundamental building blocks, quarks and gluons.

    quark
    A proton, composed of two up quarks and one down quark. (The color assignment of individual quarks is not important, only that all three colors be present.)

    inter
    In Feynman diagrams, emitted gluons are represented as helices. This diagram depicts the annihilation of an electron and positron.

    The highly energetic quarks and gluons released in the Tevatron proton-antiproton collisions produce collimated jets of particles, which can be detected by the experiments. These jets were produced in association with particles known as Z bosons.

    Fermilab Tevatron
    Tevatron at Fermilab

    You may know the Z as one of the carriers of the electroweak force, but here our focus is on their production in association with jets. The behavior of both the Z and the jets is predicted by the strong force.

    Scientists at the Tevatron experiments have made many measurements of the Z particle, which decays into a pair of leptons (electrons or muons) and jets. Our results correspond to the full Tevatron Run II data set (9.6 inverse femtobarns). In this experiment we are concerned with comparing measured probabilities with theoretical predictions. This is complicated because we must understand how well the detector records the decay particles’ tracks and energies for the process of Z boson and jet production.

    The inclusive Z-plus-jets decay probabilities are measured for one, two, three and four jets. The results shown are from combining the decay modes in which the Z decays into an electron pair and in which it decays into a muon pair. This is the first CDF measurement of probabilities for decays into a Z particle and three or more jets.

    The samples are very clean, and for the cases in which they include one or more jets, they contain only about 1.5 percent background. In the upper figure you can see results for the transverse momentum of the leading jet’s differential reaction probability for Z plus one or more jet events.

    This result is of great interest to many theoretical physicists as can be seen by the large number of predictions. The agreements are good as can be expected, as theorists have looked at earlier results from CDF and DZero. The most accurate predictions are those of a simulation program called LOOPSIM + MCFM. This is an important Tevatron legacy measurement.

    Fermilab CDF
    CDF at Fermilab

    Fermilab DZero
    DZero at Fermilab

    The results show beautiful agreement between theory and experiment and are important for understanding the association of Z and jets in searches for non-Standard Model physics.

    See the full article here.

    Fermilab Campus

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

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  • richardmitnick 11:49 am on September 3, 2014 Permalink | Reply
    Tags: , , , High Energy Physics, ,   

    From Fermilab: “From the Technical Division – Leading the way in superconducting magnets and accelerators” 


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

    Wednesday, Sept. 3, 2014

    hm
    Hasan Padamsee, head of the Technical Division, wrote this column.

    I feel very fortunate to head the Technical Division in this era of exciting accelerator technology developments. Our division holds the keys to enabling technologies for frontier accelerators, both in magnet development and accelerator cavities.

    Our niobium titanium magnet program will guide intense muon beams for precision experiments to determine whether muons, which belong to the lepton family, can spontaneously change into other leptons — specifically electrons — just as neutrinos can change into other neutrinos [electron, muon, and tau]. The magnets for the Mu2e experiment will be wound with 45 miles of superconducting cable.

    Our Nb3Sn magnet advances will enable planned upgrades to LHC luminosity guided by the LARP program, led by Giorgio Apollinari. Our Nb3Sn and high-temperature superconductor high-field magnet program, led by Alexander Zlobin, could enable a roughly 100-TeV proton-proton collider, a most powerful tool for future high-energy physics.

    As an expert in superconducting radio-frequency acceleration technology, or SRF, I was thrilled to join Fermilab in June because I saw how the division mastered our new technology to build up the infrastructure and expertise through the International Linear Collider R&D program, which ran under the leadership of Bob Kephart and previous Technical Division Head Dave Harding. To our delight, the SRF Department, led by Slava Yakovlev, had prepared some of the best niobium cavities and assembled them into the world’s highest-gradient ILC cryomodule, with a gradient of 31.5 megavolts per meter. Thus the division played a huge role in getting SRF technology ready for the ILC, if and when it will be built.

    A major consequence of the SRF successes is the decision to upgrade LCLS, the world-class light source at SLAC, using SRF technology. While the ILC must be a pulsed accelerator with a one percent duty factor, meaning that the RF power remains on for only one percent of the time, the LCLS-II light source must run continuously to keep its users happy. Continuous operation is now made economically feasible thanks to spectacular discoveries from the Technical Division.

    Anna Grassellino and Alexander Romanenko discovered new phenomena in SRF that will raise the Q values — measures of how efficiently a cavity stores energy — of ILC-type accelerating cavities from 10 billion to nearly 30 billion. To appreciate the significance of such high Qs, imagine that Galileo’s pendulum oscillator — in the year 1600 — had a Q of 30 billion. It would still be oscillating today and would continue to oscillate to the year 2800! Such high Qs arise thanks to minuscule RF losses, which make it affordable to run superconducting cavities in LCLS-II continuously. The division is gearing up to provide 17 ILC-type cryomodules with 136 cavities, as well as two cryomodules with higher-frequency cavities.

    To reap the benefits at home, SRF is also the foundation of a brand new accelerator, called PIP-II, to be constructed at Fermilab to provide the world’s best neutrino beams. PIP-II will be built in collaboration with other labs to provide a 1-megawatt proton beam accelerated by an 800-MeV superconducting linac. The linac will contain almost 20 cryomodules with more than 110 SRF cavities. The prototype cavities have been constructed and tested successfully, and the first prototype cryomodules will be assembled next year.

    Both superconducting magnets and superconducting RF have brilliant futures at Fermilab. I am proud to lead these exciting developments to keep Fermilab at the frontier of high-energy physics.

    See the full article here.

    Fermilab Campus

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

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