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  • richardmitnick 3:29 pm on October 1, 2014 Permalink | Reply
    Tags: , , , , , , , Particle Physics   

    From FNAL- “Going larger than the Large Hadron Collider: first steps toward a future machine” 


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

    Wednesday, Oct. 1, 2014
    Sanjay Padhi, Next Steps in the Energy Frontier workshop co-leader, University of California, San Diego Distinguished LPC Researcher

    In 2012, when scientists at CERN’s Large Hadron Collider discovered the Higgs boson, the machine was colliding particles at an energy of 8 teraelectronvolts, or 8 TeV. Just imagine what a 100-TeV collider could uncover.

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

    That’s what more than 80 scientists in the field of particle physics discussed at a workshop hosted by the LHC Physics Center at Fermilab from Aug. 25-28. Such a collider could unlock profound mysteries of the modern era of physics that remain unanswered. The world’s leading experts in accelerators,detectors and particle physics theory gathered to outline how the community could take the “Next Steps in the Energy Frontier” to address these questions.

    The global community has put forward two possible initiatives for a 100-TeV hadron collider: one based in Beijing, called the Super Proton Proton Collider, and one based at CERN in Geneva, the Future Circular Collider. If built, such a collider would be the largest ever, capable of probing nature at the shortest possible distance ever explored, 10-18 centimeters.

    “No matter what the next few years of experiments — in the lab, underground and in space — will unveil, the direct exploration of the shortest possible distances remains the principal probe of the fundamental laws of nature,” said CERN scientist Michelangelo Mangano. “Preparing for the next step in this endeavor is a duty, and it’s fun!”

    It would also be the first particle accelerator to have decisive coverage of exploring a weakly interacting massive particle [WIMP] dark matter candidate. It would also shed light on the mass scale related to the widely discussed naturalness aspects of nature, the asymmetry between matter and antimatter observed in our universe, rare phenomena associated with Higgs boson productions, and symmetry between matter and forces, among other unresolved matters.

    The workshop provided a platform where leaders from Beijing and CERN discussed in detail for the first time in the United States the issues attendant in realizing the technology required by such a high-energy collider: strong high-field superconducting magnets, including those that can operate at higher temperatures; precise, fast, high-resolution, radiation-hard silicon detectors only 10 to 30 microns thick; imaging energy-measuring calorimeters; next-generation computing frameworks for trigger systems and analyses and other advancements.

    “It was a very special experience to be on the ‘ground floor’ of such a grand, ambitious and worthwhile collective endeavor. The array of theorists and experimentalists at the workshop included the world’s best,” said Raman Sundrum from the University of Maryland.

    As with any innovation, these technological advancements will have an impact beyond fundamental research, benefiting industrial fields in R&D and cost. Indeed, a project of this magnitude will require synergies between various initiatives and provide international collaboration opportunities not only within the scientific communities, but also with industry. Members of the particle physics community plan to continue efforts toward a 100-TeV hadron collider, with the United States playing a central role.

    “This workshop opens a vision for the future of the study of fundamental interactions that points beyond the coming decade, continuing to follow our passion for science,” said workshop co-organizer Meenakshi Narain of Brown University.

    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 3:00 pm on October 1, 2014 Permalink | Reply
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    From FNAL- “From the CMS Center CMS: design, construction, operations” 


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

    Wednesday, Oct. 1, 2014
    sn
    Steve Nahn, U.S. CMS detector upgrade project manager, wrote this column.

    It’s a very busy and sometimes hectic place on Wilson Hall’s 10th and 11th floors these days working on CMS. Rather than progressing sequentially through design, construction and operations phases of the CMS detector upgrades, we are going through all three simultaneously. This leads to a certain amount of jumping around.

    CERN CMS New
    CMS

    The design component addresses the high-luminosity LHC era commencing in the mid-2020s, at which time the LHC’s total luminosity will increase 10-fold. To exploit the physics opportunities afforded by the more intense beam while coping with increased radiation dose, we must replace or upgrade key components of the detector. A large fraction of the collaboration spent the summer studying what sort of detector we would need in that demanding environment. The result, a 300-plus-page technical proposal, is nearly ready for release, and R&D efforts at Fermilab and collaborating institutes are already framing the technologies needed to make these Phase 2 upgrades a reality.

    The construction component, the Phase 1 Upgrade Project, is a set of strategically targeted upgrades to cope with the imminent increased instantaneous luminosity starting next year and continually growing up to the high-luminosity LHC era. The design for this phase is complete, and the job at hand is to build the new sensors, back-end electronics and online triggering system. This project just went through Critical Decision 2 and 3 reviews simultaneously. The conclusion was a resounding recommendation for approval after a few technical details are resolved. The approval, which we hope will come through in November, will allow us to transition into production mode, launching activities at SiDet, Wilson Hall and the Feynman Center at Fermilab, as well as at the 30 collaborating U.S. universities, to move the project from design to installation in the next few years.

    Lest we forget, there is the ongoing, operating experiment, perhaps the most exciting of the three phases. The LHC is poised to restart in spring 2015, after a two-year shutdown at twice the center-of-mass energy, the last significant step foreseen. The low mass of the Higgs argues for new physics that may appear in the next run, and the collaboration is gearing up to find it. This involves a program of extended running of the entire detector with cosmic rays before the beam returns to bring the detector back to peak efficiency, computing challenges to make sure the offline data production is ready, and increased effort on the analysis chain, particularly for potential early high-profile discoveries. A new discovery in 2015 would be fantastic, full stop, and we are committed to ensuring we are ready for such an opportunity.

    There is indeed a lot of exciting work going on. And amid all this, there’s still one more thing to mention: Our fearless leader Patty McBride is transitioning from U.S. CMS program manager into her role as head of the Particle Physics Division. We know she isn’t going far — only three floors down in Wilson Hall — but we’ll miss her anyway. We take this opportunity to give her a giant “thank you” for her leadership and tireless efforts up here on the 11th floor. PPD is lucky!

    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 4:34 pm on September 30, 2014 Permalink | Reply
    Tags: , , , Particle Physics, Triumf ARIEL LINAC   

    From Triumf: “ARIEL E-linac Meets Mega-Volt Milestones!” 

    30 September 2014
    Prepared by Shane Koscielniak, Lia Merminga, and Bob Laxdal.

    The campaign to demonstrate 10 MV/m accelerating gradient in the superconducting radio-frequency (SRF) cavities of the E-linac Injector (EINJ) and Accelerator (EACA) cryomodules achieved two critically important milestones last week: On Sept 23rd, the EINJ cavity reached 12 MV/m in continuous wave (c.w.) operation, exceeding design specification, and on September 24th, the EACA cavity reached 10 MV/m in c.w. operation, meeting design specification!

    areil
    ARIEL SUPERCONDUCTING ELECTRON LINAC

    To reach high gradient means the ability to accelerate a particle beam to a high voltage in a short distance; in this case 10 million electron volts over 1 metre of length! To achieve this, high power from the klystrons, on the order of 20 kW, is fed to the cavity through input couplers.

    team
    The “10MV/m SRF squad”: R. Nagimov, P. Kolb, R. Laxdal, Y.Y. Ma, W. Rawnsley, Z. Yao, V. Zvyagintsev.

    On Sept 23rd, the SRF squad produced initial results on the EINJ cavity. “We have reached 12 MV/m in both pulsed (2% duty factor) and c.w. mode. The cavity looks clean – the present limitation is only in the coupler conditioning,” reported Bob Laxdal, the SRF Group Leader.

    And on Sept 24th, the SRF squad pushed the EACA performance to 10 MV/m in c.w. operation. This builds on previous tests conducted Sept 10-13, where the EACA cavity attained 7 MV/m in c.w. and 10 MV/m in pulsed operation. “We had no doubt that the input coupler conditioning in the intervening period would make a difference, and it paid off,” says SRF Engineer Vladimir Zvyagintsev. “We will continue to condition in the coming days to further improve the performance.”

    The significance of the two results is that the cavities have reached or exceeded the specified performance for acceleration and rf power and the team believes they can go higher. “This paves the way to accelerate the electron beam up to 25 MeV later this week”, says E-linac Project Leader Shane Koscielniak. “The SRF results are pivotal to the project, and I am excited that we will be commissioning the linac with electron beam this week,” he added.

    The campaign leading to the SRF 10 Mega-Volt Milestones was five years in the making. The SRF team collaborated with the Canadian company PAVAC Industries to produce the first multi-cell elliptical cavities built in Canada, which were then processed and individually characterized in TRIUMF test cryostats, developed specifically for the ARIEL project. Several tests were required before the cavities were sufficiently optimized for assembly into the cryomodules. The cryomodules are the life support systems for the cavities – a super-thermos that allows control of the cavity while keeping it thermally isolated. Their complex design was done completely in house by the SRF team over a three year period. The two cryomodules (EINJ and EACA) have been assembled. Critical for the performance is assembly in a Class 10 clean room to keep the rf surfaces free from dust that would reduce performance.

    The cryomodules were installed in the Electron Hall during the spring and summer. A cryogenic distribution system connects the two cryomodules to the cryogenic service allowing the supply of 77 Kelvin liquid Nitrogen (LN2) for thermally shielding and 4 Kelvin liquid Helium (LHe) to cool the cavities. The final cooling of the RF cavity to 2 Kelvin is accomplished by sub-atmospheric pumping.

    Two new 300 kW klystrons were installed, commissioned and connected to the cryomodules with waveguides, while two sophisticated TRIUMF designed control systems were installed and commissioned to regulate the voltage produced by the cavity. The multitude of control and diagnostic cables were interfaced to the e-linac EPICS control system, and the thermal isolation volume and the cavity/beamline volume were evacuated and leak tested. The cooling of the cryomodules proceeded very smoothly and the cryogenic performance of the modules was measured and matched the design specification. Bob Laxdal confirmed, “The cryo-engineering of the modules is very solid – all aspects of the performance reflect the design requirements.”

    With heroic efforts on behalf of many TRIUMF groups, including cryogenics, controls, vacuum, high power and low level RF, preparations were complete for the SRF group to begin to characterize the cavity performance. The first step in applying radio-frequency power (to each cryomodule) was to condition the two input couplers; RF waves are applied to their interior metallic surfaces to eliminate electron emission. A key step was to tune the coupler and cavity so that RF power goes into the cavity, rather than being reflected away from it. “Achieving ‘lock’ of the RF components all to the same frequency is a big moment that unites hardware, electronics of the low level RF system, and controls,” Shane pointed out.

    The power from the klystron was increased slowly from a few 100 Watts to the 20 kW level, first in pulsed mode and then in continuous mode. Interlock checks were done to avoid the potential of a rapid heating of the helium due to an errant rf event. In the end all aspects of the power delivery, cryogenics, cryo-engineering, low level rf and cavity performance were successful. Vladimir Zvyagintsev, SRF Engineer, was part of the team to ‘energize’ the cavities. “It is very unusual to bring up a high power cold cavity system in such a short time, but to bring up two systems in two consecutive nights is remarkable and speaks to the quality of the installation.”

    “The rf milestones this week represent an enormous effort by a talented team. We are proud of what they have accomplished,” stated Bob Laxdal.

    team2
    “Cavity successfully energized”. The team: Chang Wei (visitor from IMP), P. Kolb, K. Fong, V. Zvyagintsev, Z. Yao, M. Laverty, Liu Yang.

    All the hard work has paid off. The ARIEL e-linac met its Mega-Volt Milestones. The ARIEL-1 project is on target!

    See the full article here.

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

    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 3:39 pm on September 17, 2014 Permalink | Reply
    Tags: , , Particle Physics,   

    From Princeton: “Neutrino experiment that reaches for the sun has Princeton roots” 

    Princeton University
    Princeton University

    September 17, 2014
    Catherine Zandonella, Office of the Dean for Research

    The detection announced Aug. 28 of an elusive subatomic particle forged in the sun’s core was a crowning achievement in the 25-year international effort to design and build one of the most sensitive neutrino detectors in the world, a feat that directly involved Princeton University scientists and engineers. With ongoing improvements in its sensitivity, the Borexino neutrino detector located a mile beneath a mountaintop at Italy’s Gran Sasso National Laboratory has the potential to reveal more about how the sun and other stars produce energy.

    Gran Sasso
    LABORATORI NAZIONALI del GRAN SASSO

    Sometimes called “ghost particles,” neutrinos are extremely difficult to detect because they slip through ordinary matter without leaving a trace. The four-story high Borexino detector is one of a handful worldwide that are capable of detecting the weakest of the neutrinos, including the proton-proton solar neutrino that is emitted during the first of several fusion reactions that generate 99 percent of the sun’s energy. The discovery of the proton-proton neutrino was reported in the journal Nature.

    “The detection of this type of solar neutrino confirms an important piece of the theory about how the sun makes energy, and if you understand the sun then you understand stars in general,” said Professor of Physics Frank Calaprice, who has led Princeton’s part of the Borexino collaboration.

    image
    The Borexino collaboration, which announced the detection of an elusive solar neutrino in August, involved several scientific contributions from Princeton over its 25-year history. The detector consists of two massive transparent nylon balloons filled with a petroleum-based liquid called “scintillator,” which emits a flash of light when it detects a neutrino. These flashes are picked up by an array of sensors embedded in a stainless steel sphere that surrounds the balloons. (Image courtesy of the Borexino collaboration)

    Although proton-proton neutrinos have been detected indirectly, Borexino is the first to measure the particles directly as well as to count the rate at which neutrinos are produced. Knowing how many neutrinos are produced tells scientists how much solar energy is being generated at the core of the sun.

    It takes tens of thousands of years for the energy made in the sun’s center to migrate to its surface. Neutrinos, on the other hand, travel at near the speed of light, reaching Earth in about eight minutes. So neutrinos essentially reveal what the sun’s surface will be like thousands of years in the future. The Borexino result revealed that the sun’s energy as measured by proton-proton neutrinos agreed with the energy measured at the sun’s surface within about 10 percent, indicating that the sun’s energy output has remained stable over the last 100,000 years or so.

    In addition to providing a way of forecasting the sun’s energy production for the next 100,000 years, the detection of these fleeting solar particles offers a way to probe the composition of the sun’s core, Calaprice said: “In principle you can tell what is happening in the center of the sun by measuring these neutrinos.”

    The standard model of the sun suggests that it is a mixed ball of hydrogen and helium with trace amounts of oxygen, carbon, nitrogen and other elements. Studies of the sun’s seismic activity have challenged that finding, however, suggesting that the core of the sun contains greater amounts of carbon, nitrogen and oxygen, while the fringes contain more hydrogen and helium.

    A type of neutrino that has not been detected before but is predicted to exist — the carbon-nitrogen neutrino — could put the controversy to rest. These neutrinos form during the process that makes the other 1 percent of the sun’s energy. Although the carbon-nitrogen process contributes little to the total energy produced in slowly evolving stars such as our sun, it is common in massive, rapidly evolving stars in the universe.

    Borexino is close to having the sort of sensitivity needed to detect carbon-nitrogen neutrinos, Calaprice said. “If we measure carbon-nitrogen neutrinos, we may be able to learn something about the amount of carbon and other elements in the core of the sun,” he said. “This could help researchers explore whether the formation of the planets affected the composition of the outer zone of the sun.”

    Balloons in Jadwin Gym

    Princeton faculty members and students have been involved in the design and construction of Borexino since its inception in the early 1990s, Calaprice said. The project is funded by Italy’s National Institute for Nuclear Physics and the U.S. National Science Foundation, as well as by science agencies from Germany, Russia, Poland, Hungary and several other countries.

    The detector, which was switched on in 2007, consists of two giant, transparent nylon balloons, one nested inside the other, that are filled with a petroleum-based liquid called “scintillator,” which emits a flash of light when a neutrino is detected. That flash of light is picked up by roughly 2,000 sensors spaced evenly around the interior of a stainless steel sphere that surrounds the balloons.

    The idea for using balloons to contain the liquid came from Calaprice’s long-time colleague, Robert Parsells, an engineer at the Princeton Plasma Physics Laboratory. “It was one of those crazy ideas that sometimes work,” Calaprice said.

    pppl

    Engineers and students at Princeton designed and built the balloons under the guidance of Calaprice and Professor of Physics Cristiano Galbiati. The team included then-graduate students Laura Cadonati, now an associate professor of physics at the University of Massachusetts-Amherst, and Andrea Pocar, now an assistant professor at the University of Massachusetts-Amherst. With Princeton engineer Allan Nelson and others, the researchers assembled the balloons — which were 28-feet and 38-feet in diameter — by gluing together strips of nylon in a dust-free “cleanroom” in the physics building. They then inflated prototypes of the balloons for testing in Princeton’s Jadwin Gym before transporting them to Italy.

    While members of the collaboration from Italy and other nations worked on the network of sensors and the electronics to process the results, the Princeton team made sure that the entire detector was free from background contaminants that could obscure the results. “Within the collaboration, the Princeton group historically has tackled some of the most challenging aspects of the experiment,” said Pocar, who now works on Borexino data analysis at Amherst and served as the corresponding author on behalf of the collaboration for the finding reported in Nature.
    Balloon construction in clean room

    team
    In the early 2000s, Princeton graduate students and engineers built large transparent nylon balloons to contain the scintillator. The team glued strips of nylon together in a special cleanroom constructed in the physics building to be as free as possible of radioactivity and dust. From left to right: Andrea Pocar, then a graduate student and now an assistant professor at the University of Massachusetts-Amherst; the late John Bahcall, a physicist at the Institute of Advance Study, who was instrumental in studying solar neutrinos and advocating for the Borexino project; and Princeton technicians Charles Sule, Allan Nelson, Elizabeth Harding (in background) and Brian Kennedy. (Image courtesy of Frank Calaprice, Department of Physics)
    Leave no trace of radioactivity

    Solar neutrinos stream from the sun to Earth at a rate of 420 billion per second per square-inch but are invisible and harmless. Their signals are nearly impossible to distinguish from the signals coming from the decay of common radioactive elements such as radon. The extremely clean and radioactive-free environment achieved at the Borexino detector has enabled the elimination of false detections, yielding the sensitivity needed for the detection of the proton-proton neutrino, which was not part of the project’s original goals, Calaprice said: “No one really thought that we could succeed with this experiment — it was too hard to get the backgrounds down as low as were needed.”

    To reduce false readings from radioactive particles — which are common in rocks and water in Italy and New Jersey — Calaprice turned to Princeton’s Jay Benziger, professor of chemical and biological engineering, an expert in the industrial-scale refining of petroleum. “We realized we needed surfaces that dust cannot stick to, so we borrowed techniques from the pharmaceutical industry, and we used purification methods borrowed from the petroleum industry, all to get the background down,” Benziger said. The resulting purification system was built and tested at Princeton before being shipped to Gran Sasso.

    In the past three years, a team of undergraduates successfully improved the purification process. Puzzled by the difficulty of removing a certain radioactive element called polonium-210, Brooke Russell, a Class of 2011 physics student who stayed on as a staff researcher, discovered a publication showing that the polonium can be converted by bacteria to another compound that allows it to resist being removed by the techniques the group was using. The team, which included William Taylor, Class of 2014, and Christian Aurup, a summer research associate and undergraduate at the University of Delaware, made adjustments to the procedure that dramatically reduced the level of the contamination. The techniques developed at Princeton to prevent false detections at Borexino have been employed in the DarkSide dark matter detector also located at Gran Sasso, as well as other neutrino and dark matter detectors around the world.

    “The thesis experience and also the two years after graduation were really pivotal for me,” Russell said. “Before doing my thesis, I had not been exposed to experimental physics. I enjoyed it so thoroughly that I decided to pursue it as a career,” said Russell, who is now in her second year of graduate studies at Yale University.

    With this latest purification step, Calaprice said, he hopes that Borexino can detect the last known solar neutrino, the carbon-nitrogen neutrino. The detector also will begin searching for the so-called “sterile neutrino” that some physicists think exists. If it is found, this type of neutrino could explain discrepancies in the so-called 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.

    The international team that reported the proton-proton neutrino in the August 28 issue of Nature included the following Princeton researchers: Borexino general engineers Augusto Goretti and Andrea Ianni; Alvaro Chavarria, who earned his doctorate in physics in 2012; Pablo Mosteiro, who earned his doctorate in physics in 2014; Richard Saldanha, who earned his doctorate in physics in 2012; R. Bruce Vogelaar, a former assistant professor now at Virginia Polytechnic Institute and State University; and Alex Wright, former postdoctoral researcher and now assistant professor at Queen’s University.

    The article, “Neutrinos from the primary proton–proton fusion process in the Sun,” was published Aug. 28 in Nature.

    See the full article here.

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 12:48 pm on September 16, 2014 Permalink | Reply
    Tags: , Particle Physics, , ,   

    From phys.org: “Neutrino trident production may offer powerful probe of new physics” 

    physdotorg
    phys.org

    September 15, 2014
    Lisa Zyga

    The standard model (SM) of particle physics has four types of force carrier particles: photons, W and Z bosons, and gluons. But recently there has been renewed interest in the question of whether there might exist a new force, which, if confirmed, would result in an extension of the SM. Theoretically, the new force would be carried by a new gauge boson called Z’ or the “dark photon” because this “dark force” would be difficult to detect, as it would affect only neutrinos and unstable leptons.

    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.

    “Much of the complexity and beauty of our physical world depends on only four forces,” Wolfgang Altmannshofer, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, told Phys.org. “It stands to reason that any additional new force discovered will bring with it interesting and unexpected phenomena, although it might take some time to fully appreciate and understand its implications.”

    Now in a new study published in Physical Review Letters, Altmannshofer and his coauthors from the Perimeter Institute have shown that the parameter space where a new dark force would exist is significantly restricted by a rare process called neutrino trident production, which has only been experimentally observed twice.

    graph
    Parameter space for the Z’ gauge boson. The light gray area is excluded at 95% C.L. by the CCFR measurement of the neutrino trident cross section. The dark gray region with the dotted contour is excluded by measurements of the SM Z boson decay to four leptons at the LHC. The purple region is the area favored by the muon g-2 discrepancy that has not yet been ruled out, but future high-energy neutrino experiments are expected to be highly sensitive to this low-mass region. Credit: Altmannshofer, et al. ©2014 American Physical Society

    In neutrino trident production, a pair of muons is produced from the scattering of a muon neutrino off a heavy atomic nucleus. If the new Z’ boson exists, it would increase the rate of neutrino trident production by inducing additional particle interactions that would constructively interfere with the expected SM contribution.

    The new force could also solve a long-standing discrepancy in the [Fermilab] muon g-2 experiment compared to the SM prediction. By coupling to muons, the new force might solve this problem.

    However, the two existing experimental results of neutrino trident production (performed by the CHARM-II collaboration and the CCFR collaboration) are both in good agreement with SM predictions, which places strong constraints on any possible contributions from a new force.

    In the new paper, the physicists have analyzed the two experimental results and extended the support for ruling out a dark force, at least over a large portion of the parameter space relevant to solving the muon g-2 discrepancy (when the mass of the Z’ boson is greater than about 400 MeV). The results not only constrain the dark force, but more generally any new force that couples to both muons and muon neutrinos.

    “We showed that neutrino trident production is the most sensitive probe of a certain type of new force,” Altmannshofer said. “Particle physics is driven by the desire to discover new building blocks of nature, and ultimately the principles that organize these building blocks. Our findings establish a new direction where new forces can be searched for, and highlight the planned neutrino facility at Fermilab (the Long-Baseline Neutrino Experiment [LBNE]) as a potentially powerful experiment where such forces can be searched for in the future.”

    Overall, the current results suggest that LBNE would have very favorable prospects for searching for the Z’ boson in the relevant, though restricted, regions of parameter space.

    See the full article here.

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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  • richardmitnick 10:50 am on September 16, 2014 Permalink | Reply
    Tags: , , , , , , Particle Physics   

    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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