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  • richardmitnick 2:42 pm on October 20, 2014 Permalink | Reply
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    From FNAL: “New high-speed transatlantic network to benefit science collaborations across the U.S.” 


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

    Monday, Oct. 20, 2014

    Karen McNulty-Walsh, Brookhaven Media and Communications Office, kmcnulty@bnl.gov, 631-344-8350
    Kurt Riesselmann, Fermilab Office of Communication, media@fnal.gov, 630-840-3351
    Jon Bashor, Computing Sciences Communications Manager, Lawrence Berkeley National Laboratory, jbashor@lbnl.gov, 510-486-5849

    Scientists across the United States will soon have access to new, ultra-high-speed network links spanning the Atlantic Ocean thanks to a project currently under way to extend ESnet (the U.S. Department of Energy’s Energy Sciences Network) to Amsterdam, Geneva and London. Although the project is designed to benefit data-intensive science throughout the U.S. national laboratory complex, heaviest users of the new links will be particle physicists conducting research at the Large Hadron Collider (LHC), the world’s largest and most powerful particle collider. The high capacity of this new connection will provide U.S. scientists with enhanced access to data at the LHC and other European-based experiments by accelerating the exchange of data sets between institutions in the United States and computing facilities in Europe.

    esnet

    DOE’s Brookhaven National Laboratory and Fermi National Accelerator Laboratory—the primary computing centers for U.S. collaborators on the LHC’s ATLAS and CMS experiments, respectively—will make immediate use of the new network infrastructure once it is rigorously tested and commissioned. Because ESnet, based at DOE’s Lawrence Berkeley National Laboratory, interconnects all national laboratories and a number of university-based projects in the United States, tens of thousands of researchers from all disciplines will benefit as well.

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

    CERN ATLAS New
    ATLAS at the LHC

    CERN CMS New
    CMS at CERN

    BNL Campus
    Brookhaven Lab

    The ESnet extension will be in place before the LHC at CERN in Switzerland—currently shut down for maintenance and upgrades—is up and running again in the spring of 2015. Because the accelerator will be colliding protons at much higher energy, the data output from the detectors will expand considerably—to approximately 40 petabytes of raw data per year compared with 20 petabytes for all of the previous lower-energy collisions produced over the three years of the LHC first run between 2010 and 2012.

    The cross-Atlantic connectivity during the first successful run for the LHC experiments, which culminated in the discovery of the Higgs boson, was provided by the US LHCNet network, managed by the California Institute of Technology. In recent years, major research and education networks around the world—including ESnet, Internet2, California’s CENIC, and European networks such as DANTE, SURFnet and NORDUnet—have increased their backbone capacity by a factor of 10, using sophisticated new optical networking and digital signal processing technologies. Until recently, however, higher-speed links were not deployed for production purposes across the Atlantic Ocean—creating a network “impedance mismatch” that can harm large, intercontinental data flows.

    An evolving data model

    This upgrade coincides with a shift in the data model for LHC science. Previously, data moved in a more predictable and hierarchical pattern strongly influenced by geographical proximity, but network upgrades around the world have now made it possible for data to be fetched and exchanged more flexibly and dynamically. This change enables faster science outcomes and more efficient use of storage and computational power, but it requires networks around the world to perform flawlessly together.

    “Having the new infrastructure in place will meet the increased need for dealing with LHC data and provide more agile access to that data in a much more dynamic fashion than LHC collaborators have had in the past,” said physicist Michael Ernst of DOE’s Brookhaven National Laboratory, a key member of the team laying out the new and more flexible framework for exchanging data between the Worldwide LHC Computing Grid centers.

    Ernst directs a computing facility at Brookhaven Lab that was originally set up as a central hub for U.S. collaborators on the LHC’s ATLAS experiment. A similar facility at Fermi National Accelerator Laboratory has played this role for the LHC’s U.S. collaborators on the CMS experiment. These computing resources, dubbed Tier 1 centers, have direct links to the LHC at the European laboratory CERN (Tier 0). The experts who run them will continue to serve scientists under the new structure. But instead of serving as hubs for data storage and distribution only among U.S.-based collaborators at Tier 2 and 3 research centers, the dedicated facilities at Brookhaven and Fermilab will be able to serve data needs of the entire ATLAS and CMS collaborations throughout the world. And likewise, U.S. Tier 2 and Tier 3 research centers will have higher-speed access to Tier 1 and Tier 2 centers in Europe.

    “This new infrastructure will offer LHC researchers at laboratories and universities around the world faster access to important data,” said Fermilab’s Lothar Bauerdick, head of software and computing for the U.S. CMS group. “As the LHC experiments continue to produce exciting results, this important upgrade will let collaborators see and analyze those results better than ever before.”

    Ernst added, “As centralized hubs for handling LHC data, our reliability, performance and expertise have been in demand by the whole collaboration, and now we will be better able to serve the scientists’ needs.”

    An investment in science

    ESnet is funded by DOE’s Office of Science to meet networking needs of DOE labs and science projects. The transatlantic extension represents a financial collaboration, with partial support coming from DOE’s Office of High Energy Physics (HEP) for the next three years. Although LHC scientists will get a dedicated portion of the new network once it is in place, all science programs that make use of ESnet will now have access to faster network links for their data transfers.

    “We are eagerly awaiting the start of commissioning for the new infrastructure,” said Oliver Gutsche, Fermilab scientist and member of the CMS Offline and Computing Management Board. “After the Higgs discovery, the next big LHC milestones will come in 2015, and this network will be indispensable for the success of the LHC Run 2 physics program.”

    This work was supported by the DOE Office of Science.

    The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article here.

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    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 2:05 pm on October 17, 2014 Permalink | Reply
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    From FNAL- “Frontier Science Result: CMS Off the beaten path” 


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

    Friday, Oct. 17, 2014
    Jim Pivarski

    The main concern for most searches for rare phenomena is to control the backgrounds. Backgrounds are observations that resemble the one of interest, yet aren’t. For instance, fool’s gold is a background for gold prospectors. The main reason that the Higgs boson was hard to find is that most Higgs decays resemble b quark pair production, which is a million times more common. You not only have to find the one-in-a-million event picture, you have to identify some feature of it to prove that it is not an ordinary event.

    This is particularly hard to do in proton collisions because protons break apart in messy ways — the quarks from the proton that missed each other generate a spray of particles that fly off just about everywhere. Look through a billion or a trillion of these splatter events and you can find one that resembles the pattern of new physics that you’re looking for. Physicists have many techniques for filtering out these backgrounds — requiring missing momentum from an invisible particle, high energy perpendicular to the beam, a resonance at a single energy, and the presence of electrons and muons are just a few.

    nu
    Most particles produced by proton collisions originate in the point where the beams cross. Those that do not are due to intermediate particles that travel some distance before they decay

    A less common yet powerful technique for eliminating backgrounds is to look for displaced particle trajectories, meaning trajectories that don’t intersect the collision point. Particles that are directly created by the proton collision or are created by short-lived intermediates always emerge from this point. Those that emerge from some other point in space must be due to a long-lived intermediate.

    A common example of this is the b quark, which can live as long as a trillionth of a second before decaying into visible particles. That might not sound like very long, but the quark is traveling so quickly that it covers several millimeters in that trillionth of a second, which is a measurable difference.

    In a recent analysis, CMS scientists searched for displaced electrons and muons. Displaced tracks are rare, and electrons and muons are also rare, so displaced electrons and muons should be extremely rare. The only problem with this logic is that b quarks sometimes produce electrons and muons, so one other feature is needed to disambiguate. A b quark almost always produces a jet of particles, so this search for new physics also required that the electrons and muons were not close to jets.

    CERN CMS New
    CERN CMS

    With these simple selection criteria, the experimenters found only as many events as would be expected from standard physics. Therefore, it constrains any theory that predicts displaced electrons and muons. One of these is “displaced supersymmetry,” which generalizes the usual supersymmetry scenario by allowing the longest-lived supersymmetric particle to decay on the millimeter scale that this analysis tests. Displaced supersymmetry was introduced as a way that supersymmetry might exist yet be missed by most other analyses. Experiments like this one illuminate the dark corners in which supersymmetry might be hiding.

    See the full article here.

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  • richardmitnick 2:52 pm on October 16, 2014 Permalink | Reply
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    From LC Newsline: “Full ILC-type cryomodule makes the grade” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    16 October 2014
    Joykrit Mitra

    For the first time, the ILC gradient specification of 31.5 megavolts per metre has been achieved on average across all of the eight cavities assembled in an ILC-type cryomodule. A team at Fermilab reached the milestone earlier this month. It is an achievement for scientists, engineers and technicians at Fermilab and Jefferson Lab in Virginia as well as their domestic and international partners in superconducting radio-frequency (SRF) technologies.

    The cryomodule, called CM2, was developed and assembled to advance superconducting radio-frequency technology and infrastructure at Americas-region laboratories. The CM2 milestone achievement has been nearly a decade in the making, since US scientists started participating in ILC research and development in 2006.

    cryo
    CM2 cryomodule being assembled at Fermilab’s Industrial Center Building (2011). Photo: Reidar Hahn

    “We’ve reached this important milestone and it was a long time coming,” said Elvin Harms, who leads the cryomodule testing programme at Fermilab. “It’s the first time in the world this has been achieved.”

    An accelerating gradient is a measure of how much of an energy boost particle bunches receive as they zip through an accelerator. Cavities with higher gradients boost particle bunches to higher energies over shorter distances. In an operational ILC, all 16,000 of its cavities would be housed in cryomodules, which would keep the cavities cool when operating at a temperature of 2 kelvins. While cavities can achieve high gradients as standalones, when they are assembled together in a cryomodule unit, the average gradient drops significantly.

    The road to the 31.5 MV/m milestone has been a long and arduous one. Between 2008 and 2010, all of the eight cavities in CM2 had individually been pushed to gradients above 35 MV/m at Jefferson Lab in tests in which the cavities were electropolished and vertically oriented. They were among 60 cavities evaluated globally for the prospects of reaching the ILC gradient. This evaluation was known as the S0 Global Design Effort. It was a build-up to the S1-Global Experiment, which put to the test the possibility of reaching 31.5 MV/m across an entire cryomodule. The final assembly of the S1 cryomodule setup took place at KEK in Japan, between 2010 and 2011. In S1, seven nine-cell 1.3-gigahertz niobium cavities strung together inside a cryomodule achieved an average gradient of 26 MV/m. An ILC-type cryomodule consists of eight such cavities.

    cm2
    CM2 in its home at Fermilab’s NML building, as part of the future Advanced Superconducting Test Accelerator. Photo: Reidar Hahn

    But the ILC community has taken big strides since then. Americas region teams acquired significant expertise in increasing cavity gradients: all CM2 cavities were vertically tested in the United States, initially at Jefferson Lab, and were subjected to additional horizontal tests at Fermilab. Further, cavities manufactured by private vendors in the United States have improved in quality: three of the eight cavities that make up the CM2 cryomodule were fabricated locally.

    Hands-on experience played a major role in improving the overall CM2 gradient. In 2007, a kit for Fermilab’s Cryomodule 1, or CM1, arrived from DESY, and by 2010, when CM1 was operational, the workforce had adopted a production mentality, which was crucial for the work they did on CM2.

    “I would like to congratulate my Fermilab colleagues for their persistence in carrying out this important work and for the quality of their work, which is extremely high,” said the SRF Institute at Jefferson Lab’s Rongli Geng, who led the ILC high-gradient cavity project there from 2007 to 2012. “We are glad to be able to contribute to this success.”

    But achieving the gradient is only the first step, Harms said. “There is still a lot of work left to be done. We need to look at CM2’s longer term performance. And we need to evaluate it thoroughly.”

    Among other tasks, the CM2 group will gently push the gradients higher to determine the limits of the technology and continue to understand and refine it. They plan to power and check the magnet—manufactured at Fermilab— that will be used to focus the particle beam passing through the cryomodule. Also in the works is a plan to study the rate at which the CM2 can be cooled down to 2 kelvins and warmed up again. Finally, they expect to send an actual electron beam through CM2 in 2015 to understand better how the beam and cryomodule respond in that setup.

    Scientists at Fermilab also expect that CM2 will be used in the Advanced Superconducting Test Accelerator currently under construction at Fermilab’s NML building, where CM2 is housed. The SRF technology developed for CM2 also has applications for light source instruments such as LCLS-II at SLAC in the United States and DESY’s XFEL.

    And it’s definitely a viable option for a future machine like the ILC.

    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 2:30 pm on October 16, 2014 Permalink | Reply
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    From LC Newsline: “Calorimeters enjoy beam time” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    16 October 2014
    Barbara Warmbein

    There are prototypes and there are prototypes. Some are needed to verify that a chosen detection technology actually works, some help scientists test one technology against another, some help them design sturdy detector infrastructure with little material budget, working power supply and cooling, while others set out to prove that it is possible to have full detector functionality with all electronics set up like in the final detector. And then there are those that do it all at the same time.

    calice
    CALICE crowd around detector setup in the T9 beamline at CERN. All images by Katsushige Kotera

    The CALICE collaboration’s analogue hadronic calorimeter, or AHCAL, is an example of the last type. It is a prototype for a calorimeter – a subdetector that measures the energies of passing particles – that might one day be part of the ILD detector. It would work together with trackers, electromagnetic calorimeter and muon system to record, reconstruct, track and identify every particle produced in the collisions at the future ILC. The CALICE scientists are currently testing a prototype that takes a close look at detector infrastructure like cooling and power supply while at the same time comparing different kinds of silicon photomultipliers or SiPMs. These do the actual job of detection, and the collaboration is testing the latest and much advanced commercial silicon photomultipliers (SiPMs) from Russia, Ireland, Japan and Germany.

    fd
    Flying detectors: after craning the hadronic calorimeter into its test beam destination…
    in
    …it gets installed and set up before starting its data taking run.

    The HCAL prototype consists of one module, which corresponds to a slice of one sector of the future calorimeter barrel of the final detector. It has 1000 channels per square metre and it shares the space in the test beam area with CALICE electromagnetic calorimeter prototype modules from Japan – a true collaboration that also shares the same readout electronics. It’s also the first time that these calorimeters are taking data in a hadron beam after a few runs in electron beams at DESY in Germany.

    …it gets installed and set up before starting its data taking run.

    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 1:51 pm on October 15, 2014 Permalink | Reply
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    From Symmetry: “Top quark still raising questions” 

    Symmetry

    October 15, 2014
    Troy Rummler

    Why are scientists still interested in the heaviest fundamental particle nearly 20 years after its discovery?

    “What happens to a quark deferred?” the poet Langston Hughes may have asked, had he been a physicist. If scientists lost interest in a particle after its discovery, much of what it could show us about the universe would remain hidden. A niche of scientists, therefore, stay dedicated to intimately understanding its properties.

    tq
    Photo by Reidar Hahn, Fermilab

    Case in point: Top 2014, an annual workshop on top quark physics, recently convened in Cannes, France, to address the latest questions and scientific results surrounding the heavyweight particle discovered in 1995 (early top quark event pictured above).

    Top and Higgs: a dynamic duo?

    A major question addressed at the workshop, held from September 29 to October 3, was whether top quarks have a special connection with Higgs bosons. The two particles, weighing in at about 173 and 125 billion electronvolts, respectively, dwarf other fundamental particles (the bottom quark, for example, has a mass of about 4 billion electronvolts and a whole proton sits at just below 1 billion electronvolts).

    Prevailing theory dictates that particles gain mass through interactions with the Higgs field, so why do top quarks interact so much more with the Higgs than do any other known particles?

    Direct measurements of top-Higgs interactions depend on recording collisions that produce the two side-by-side. This hasn’t happened yet at high enough rates to be seen; these events theoretically require higher energies than the Tevatron or even the LHC’s initial run could supply. But scientists are hopeful for results from the next run at the LHC.

    “We are already seeing a few tantalizing hints,” says Martijn Mulders, staff scientist at CERN. “After a year of data-taking at the higher energy, we expect to see a clear signal.” No one knows for sure until it happens, though, so Mulders and the rest of the top quark community are waiting anxiously.

    A sensitive probe to new physics

    Top and anti-top quark production at colliders, measured very precisely, started to reveal some deviations from expected values. But in the last year, theorists have responded by calculating an unprecedented layer of mathematical corrections, which refined the expectation and promise to realigned the slightly rogue numbers.

    Precision is an important, ongoing effort. If researchers aren’t able to reconcile such deviations, the logical conclusion is that the difference represents something they don’t know about—new particles, new interactions, new physics beyond the standard model.

    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 challenge of extremely precise measurements can also drive the formation of new research alliances. Earlier this year, the first Fermilab-CERN joint announcement of collaborative results set a world standard for the mass of the top quark.

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

    Such accuracy hones methods applied to other questions in physics, too, the same way that research on W bosons, discovered in 1983, led to the methods Mulders began using to measure the top quark mass in 2005. In fact, top quark production is now so well controlled that it has become a tool itself to study detectors.
    Forward-backward synergy

    With the upcoming restart in 2015, the LHC will produce millions of top quarks, giving researchers troves of data to further physics. But scientists will still need to factor in the background noise and data-skewing inherent in the instruments themselves, called systematic uncertainty.

    “The CDF and DZero experiments at the Tevatron are mature,” says Andreas Jung, senior postdoc at Fermilab. “It’s shut down, so the understanding of the detectors is very good, and thus the control of systematic uncertainties is also very good.”

    FNALTevatron
    Tevatron at Fermilab

    FNAL CDF
    CDF experiment at the Tevatron

    FNAL DZero
    DZero at the Tevatron

    Jung has been combing through the old data with his colleagues and publishing new results, even though the Tevatron hasn’t collided particles since 2011. The two labs combined their respective strengths to produce their joint results, but scientists still have much to learn about the top quark, and a new arsenal of tools to accomplish it.

    “DZero published a paper in Nature in 2004 about the measurement of the top quark mass that was based on 22 events,” Mulders says. “And now we are working with millions of events. It’s incredible to see how things have evolved over the years.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 7:38 pm on October 14, 2014 Permalink | Reply
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    From New Scientist vis FNAL: “Two new strange and charming particles appear at LHC” 

    NewScientist

    New Scientist

    08 October 2014
    Nicola Jenner

    Two new particles have been discovered by the LHCb experiment at CERN’s Large Hadron Collider near Geneva, Switzerland. One of them has a combination of properties that has never been observed before.

    CERN LHCb New
    LHCb

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

    The particles, named DS3*(2860)– and DS1*(2860)–, are about three times as massive as protons.

    Physicists analyzed LHCb observations of an energy peak that had been spotted in 2006 by the BaBar experiment at Stanford University in California, but whose cause was still unknown.

    “Our result shows that the BaBar peak is caused by two new particles,” says Tim Gershon of Warwick University, UK, lead author of the discovery.
    The force is strong

    Mesons are particles that contain two quarks – subatomic particles that make up matter and are thought to be indivisible. These quarks are bound together by the strong force, one of the four fundamental forces that also keeps the constituents of nuclei together within atoms. This force is one of the less well-understood parts of the standard model of particle physics, the incomplete theory that describes how particles interact.

    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.

    Quarks come in six different flavours known as up, down, strange, charm, bottom and top, in order from lightest to heaviest. The new particles each contain one charm antiquark and one strange quark.

    Significantly, DS3*(2860)– also has a spin value of 3, making this discovery the first ever observation of a spin-3 particle containing a charm quark.

    In other mesons, the quarks can be configured in one of several different ways to give the particle an overall spin value less than three, and this makes the quarks’ exact properties ambiguous. However, for a spin value of three there is no such ambiguity, making DS3*(2860)–’s precise configuration clear.

    Combined with the particle’s charm quark, this may make DS3*(2860)– a key player for exploring the strong force, because the calculations involved are more straightforward for heavy quarks than for lighter ones.

    The LHCb team used a technique known as Dalitz plot analysis to untangle the data peak into its two components, a complex technique that had never before been used on LHC data.

    The technique helps separate and visualise the different paths a particle can take as it decays. Now that it has been used successfully on the LHCb dataset, says Gershon, it can hopefully be applied to more LHC data to help discover further particles and understand how they are bound together.

    “This is a lovely piece of experimental physics,” says Robert Jaffe of the Massachusetts Institute of Technology in Cambridge. “Although it doesn’t probe the limits of the standard model, it may shine light on the dynamics of quarks and gluons. The fact that LHCb was able to use Dalitz plot methods is a testimony to the quantity and high quality of the data they’ve accumulated. We can look forward to other similar discoveries in the future using this method.”

    See the full article here.

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  • richardmitnick 1:29 pm on October 9, 2014 Permalink | Reply
    Tags: , , , , , Particle Physics, University of Warwick   

    From Warwick: “Discovery of new subatomic particle sheds light on fundamental force of nature “ 

    University of Warwick

    University of Warwick

    9 October 2014
    No Writer Credit

    The discovery of a new particle will “transform our understanding” of the fundamental force of nature that binds the nuclei of atoms, researchers argue.

    Led by scientists from the University of Warwick, the discovery of the new particle will help provide greater understanding of the strong interaction, the fundamental force of nature found within the protons of an atom’s nucleus.

    what
    Credit: Science and Technology Facilities Council

    Named Ds3*(2860)ˉ, the particle, a new type of meson,[1] was discovered by analysing data collected with the LHCb detector at CERN’s Large Hadron Collider (LHC)[2]. The LHCb experiment, which is run by a large international collaboration, is designed to study the properties of particles containing beauty and charm quarks and has unique capability for this kind of discovery.

    CERN LHCb New
    LHCb

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

    The new particle is bound together in a similar way to protons. Due to this similarity, the Warwick researchers argue that scientists will now be able to study the particle to further understand strong interactions.

    Along with gravity, the electromagnetic interaction and weak nuclear force, strong-interactions are one of four fundamental forces. Lead scientist Professor Tim Gershon, from The University of Warwick’s Department of Physics, explains:

    “Gravity describes the universe on a large scale from galaxies to [Isaac] Newton’s falling apple, whilst the electromagnetic interaction is responsible for binding molecules together and also for holding electrons in orbit around an atom’s nucleus.

    “The strong interaction is the force that binds quarks, the subatomic particles that form protons within atoms, together. It is so strong that the binding energy of the proton gives a much larger contribution to the mass, through [Albert] Einstein’s equation E = mc2, than the quarks themselves.[3]”

    Due in part to the forces’ relative simplicity, scientists have previously been able to solve the equations behind gravity and electromagnetic interactions, but the strength of the strong interaction makes it impossible to solve the equations in the same way.

    “Calculations of strong interactions are done with a computationally intensive technique called Lattice QCD,” says Professor Gershon. “In order to validate these calculations it is essential to be able to compare predictions to experiments. The new particle is ideal for this purpose because it is the first known that both contains a charm quark and has spin 3.”

    There are six quarks known to physicists; Up, Down, Strange, Charm, Beauty and Top. Protons and neutrons are composed of up and down quarks, but particles produced in accelerators such as the LHC can contain the unstable heavier quarks. In addition, some of these particles have higher spin values than the naturally occurring stable particles.

    “Because the Ds3*(2860)ˉ particle contains a heavy charm quark it is easier for theorists to calculate its properties. And because it has spin 3, there can be no ambiguity about what the particle is,” adds Professor Gershon. “Therefore it provides a benchmark for future theoretical calculations. Improvements in these calculations will transform our understanding of how nuclei are bound together.”

    Spin is one of the labels used by physicists to distinguish between particles. It is a concept that arises in quantum mechanics that can be thought of as being similar to angular momentum: in this sense higher spin corresponds to the quarks orbiting each other faster than those with a lower spin.

    Warwick Ph.D. student Daniel Craik, who worked on the study, adds “Perhaps the most exciting part of this new result is that it could be the first of many similar discoveries with LHC data. Whether we can use the same technique, as employed with our research into Ds3*(2860)ˉ, to also improve our understanding of the weak interaction is a key question raised by this discovery. If so, this could help to answer one of the biggest mysteries in physics: why there is more matter than antimatter in the Universe.”

    The results are detailed in two papers that will be published in the next editions of the journals Physical Review Letters and Physical Review D. Both papers have been given the accolade of being selected as Editors’ Suggestions.

    [1] The Ds3*(2860)ˉ particle is a meson that contains a charm anti-quark and a strange quark. The subscript 3 denotes that it has spin 3, while the number 2860 in parentheses is the mass of the particle in the units of MeV/c2 that are favoured by particle physicists. The value of 2860 MeV/c2 corresponds to approximately 3 times the mass of the proton.

    [2] The particle was discovered in the decay chain Bs0→D0K–π+ , where the Bs0, D0, K– and π+ mesons contain respectively a bottom anti-quark and a strange quark, a charm anti-quark and an up quark, an up anti-quark and a strange quark, and a down anti-quark and an up quark. The Ds3*(2860)ˉ particle is observed as a peak in the mass of combinations of the D0 and K– mesons. The distributions of the angles between the D0, K– and π+ particles allow the spin of the Ds3*(2860)ˉ meson to be unambiguously determined.

    [3] Quarks are bound by the strong interaction into one of two types of particles: baryons, such as the proton, are composed of three quarks; mesons are composed of one quark and one anti-quark, where an anti-quark is the antimatter version of a quark.

    See the full article here.

    Warwick Campus

    The establishment of the University of Warwick was given approval by the government in 1961 and received its Royal Charter of Incorporation in 1965.

    The idea for a university in Coventry was mooted shortly after the conclusion of the Second World War but it was a bold and imaginative partnership of the City and the County which brought the University into being on a 400-acre site jointly granted by the two authorities. Since then, the University has incorporated the former Coventry College of Education in 1978 and has extended its land holdings by the purchase of adjoining farm land.

    The University initially admitted a small intake of graduate students in 1964 and took its first 450 undergraduates in October 1965. In October 2013, the student population was over 23,000 of which 9,775 are postgraduates. Around a third of the student body comes from overseas and over 120 countries are represented on the campus.

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  • richardmitnick 9:02 pm on October 5, 2014 Permalink | Reply
    Tags: , , Particle Physics   

    From ars technica: “Exploring the monstrous creatures at the edges of the dark matter map” 

    Ars Technica
    ars technica

    Sept 30 2014
    Matthew Francis

    So far, we’ve focused on the simplest dark matter models, consisting of one type of object and minimal interactions among individual dark matter particles. However, that’s not how ordinary matter behaves: the interactions among different particle types enable the existence of atoms, molecules, and us. Maybe the same sort of thing is true for dark matter, which could be subject to new forces acting primarily between particles.

    Some theories describe a kind of “dark electromagnetism” where particles carry charges like electricity, but they’re governed by a force that doesn’t influence electrons and the like. Just as normal electromagnetism describes light, these models include “dark photons,” which sound like something from the last season of Star Trek: The Next Generation (after the writers ran out of ideas).

    elec
    Diagram of a solenoid and its magnetic field lines. The shape of all lines is correct according to the laws of electrodynamics.

    Like many WDM candidates, dark photons would be difficult—if not impossible—to detect directly, but if they exist, they would carry energy away from interacting dark matter systems. That would be detectable by its effect on things like the structure of neutron stars and other compact astronomical bodies. Observations of these objects would let researchers place some stringent limits on the strength of dark forces. Another consequence is that dark forces would tend to turn spherical galactic halos into flatter, more disk-like structures. Since we don’t see that in real galaxies, there are strong constraints on how much dark forces can affect dark matter motion.

    som
    The “Sombrero” galaxy shows that matter interacting with itself flattens into disks. Dark matter doesn’t seem to do that, limiting the strength of possible interactions between particles.
    NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

    NASA Hubble Telescope
    NASA/ESA Hubble

    Another side effect of dark forces is that there should be dark antimatter and dark matter-antimatter annihilation. The results of such interactions could include ordinary photons, another intriguing hint in the wake of observations of excess gamma-rays, possibly due to dark matter annihilation in the Milky Way and other galaxies.

    What’s cooler than cold dark matter?

    While most low-mass particles are “hot,” a hypothetical particle known as the axion is an exception. Axions were first predicted as a solution to a thorny problem in the physics of the strong nuclear force, but certain properties make them appealing as dark matter candidates. Mainly, they are electrically neutral and don’t interact directly with ordinary matter except through gravity.

    Axions are also very low-mass (at least in one proposed version), but unlike hot dark matter, they “condensed” in the early Universe into a slow, thick soup. In other words, they behave much like cold dark matter, but without the large mass usually implied by the term.

    Axions aren’t part of the Standard Model, but in a sense they’re a minimally invasive addition. Unlike supersymmetry, which involves adding one particle for each type in the Standard Model, axions are just one particle type, albeit one with some unique properties. (To be fair, these aren’t mutually exclusive concepts: it’s possible both SUSY particles and axions are real, and some versions of SUSY even include a hypothetical partner for axions.)

    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.

    Supersymmetry standard model
    Standard Model of Supersymmetry

    Like WDM, axions don’t interact directly with ordinary matter. But according to theory, in a strong magnetic field, axions and photons can oscillate into each other, switching smoothly between particle types. That means axions could be created all the time near black holes, neutron stars, or other places with intense magnetic fields—possibly including superconducting circuits here on Earth. This is how experiments hunt for axions, most notably the Axion Dark Matter eXperiment (ADMX).

    So far, no experiment has turned up axions, at least of the type we’d expect to see. Particle physics has a lot of wiggle-room for possibilities, so it’s too soon to say no axions exist, but axion partisans are disappointed. A universe with axions makes more sense than one without, but it wouldn’t be the first time something that really seemed to be a good idea didn’t quite work out.

    A physicist’s fear

    Long as it is becoming, this list is far from complete. We’ve excluded exotic particles with sufficiently tiny electric charges to be nearly invisible, weird (but unlikely) interactions that change the character of known particles under special circumstances, plus a number of other possibilities. One interesting candidate is jokingly known a WIMPzilla, which consists of one or more particle type more than a trillion times the mass of a proton. These would have been born at a much earlier era than WIMPs, when the Universe was even hotter. Because they are so much heavier, WIMPzillas can be rarer and interact more readily with normal matter, but—as with other more exotic candidates—they aren’t really considered to be a strong possibility.

    godzilla
    If the leading ideas for dark matter don’t hold up to experimental scrutiny, then we’ve definitely sailed off the map into the unknown.
    Castle Gallery, College of New Rochelle

    And more non-WIMP dark matter candidates seem to crop up every year, though many are implausible enough they won’t garner much attention even from other theorists. However, each guess—even unlikely ones—can help us understand what dark matter can be, and what it can’t.

    We’ve also omitted a whole other can of worms known as “modified gravity”—a proposition that the matter we see is all there is, and the observational phenomena that don’t make sense can be explained by a different theory of gravity. So far, no modified gravity model has reproduced all the observed phenomena attributed to dark matter, though of course that doesn’t say it can never happen.

    To put it another way: most astronomers and cosmologists accept that dark matter exists because it’s the simplest explanation that accounts for all the observational data. If you want a more grumpy description, you could say that dark matter is the worst idea, except for all the other options.

    Of course, Nature is sly. Perhaps more than one of these dark matter candidates is out there. A world with both axions and WIMPs—motivated as they are by different problems arising from the Standard Model—would be confounding but not beyond reason. Given the unexpected zoo of normal particles discovered in the 20th century, maybe we’ll be pleasantly surprised; after all, wouldn’t it be nice if several of our hypotheses were simultaneously correct for once? (I’m a both/and kind of guy.) More than one type might also help explain why we have yet to see any dark matter in our detectors so far. If a substantial fraction of dark matter particles is made of axions, then the density of WIMPs or WDM must be correspondingly lower and vice versa.

    But a bigger worry lurks in the minds of many researchers. Maybe dark matter doesn’t interact with ordinary matter at all, and it doesn’t annihilate in a way we can detect easily. Then the “dark sector” is removed from anything we can probe experimentally, and that’s an upsetting thought. Researchers would have a hard time explaining how such particles came to be after the Big Bang, but worse: without a way to study their properties in the lab, we would be stuck with the kind of phenomenology we have now. Dark matter would be perpetually assigned to placeholder status.

    In old maps made by European cartographers, distant lands were sometimes shown populated by monstrous beings. Today of course, everyone knows that those lands are inhabited by other human beings and creatures that, while sometimes strange, aren’t the monsters of our imagination. Our hope is that the monstrous beings of our theoretical space imaginings will some day seem ordinary, too, and “dark matter” will be part of physics as we know it.

    See the full article here.

    Ars Technica was founded in 1998 when Founder & Editor-in-Chief Ken Fisher announced his plans for starting a publication devoted to technology that would cater to what he called “alpha geeks”: technologists and IT professionals. Ken’s vision was to build a publication with a simple editorial mission: be “technically savvy, up-to-date, and more fun” than what was currently popular in the space. In the ensuing years, with formidable contributions by a unique editorial staff, Ars Technica became a trusted source for technology news, tech policy analysis, breakdowns of the latest scientific advancements, gadget reviews, software, hardware, and nearly everything else found in between layers of silicon.

    Ars Technica innovates by listening to its core readership. Readers have come to demand devotedness to accuracy and integrity, flanked by a willingness to leave each day’s meaningless, click-bait fodder by the wayside. The result is something unique: the unparalleled marriage of breadth and depth in technology journalism. By 2001, Ars Technica was regularly producing news reports, op-eds, and the like, but the company stood out from the competition by regularly providing long thought-pieces and in-depth explainers.

    And thanks to its readership, Ars Technica also accomplished a number of industry leading moves. In 2001, Ars launched a digital subscription service when such things were non-existent for digital media. Ars was also the first IT publication to begin covering the resurgence of Apple, and the first to draw analytical and cultural ties between the world of high technology and gaming. Ars was also first to begin selling its long form content in digitally distributable forms, such as PDFs and eventually eBooks (again, starting in 2001).

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  • richardmitnick 1:38 pm on October 3, 2014 Permalink | Reply
    Tags: , , , , LIGO, Particle Physics,   

    From Symmetry: “To catch a gravitational wave” 

    Symmetry

    October 03, 2014
    Jessica Orwig

    Advanced LIGO, designed to detect gravitational waves, will eventually be 1000 times more powerful than its predecessor.

    Thirty years ago, a professor and a student with access to a radiotelescope in Puerto Rico made the first discovery of a binary pulsar: a cosmic dance between a pair of small, dense, rapidly rotating neutron stars, called pulsars, in orbit around one another.

    Scientists noticed that their do-si-do was gradually speeding up, which served as indirect evidence for a phenomenon predicted by Albert Einstein called gravitational waves.

    Today in Livingston, Louisiana, and Hanford, Washington, scientists are preparing the next stage of a pair of experiments that they hope will detect gravitational waves directly within the next five years. They’re called the Laser Interferometer Gravitational-Wave Observatory, or LIGO.

    Distorting the fabric of spacetime

    Gravitational waves are faint ripples in the fabric of spacetime thought to propagate throughout the universe. According to the theory of general relativity, objects with mass—and therefore gravitational pull—should emit these waves whenever they accelerate. Scientists think the stars in the binary pulsar that Russell Hulse and Joseph Taylor discovered in 1974 are being pulled closer and closer together because they are losing miniscule amounts of energy each year through the emission of gravitational waves.

    If a gravitational wave from a binary pulsar passes through Livingston or Hanford, the LIGO experiments will be waiting. In summer 2015, scientists will begin collecting data with Advanced LIGO, the next stage of LIGO, with more powerful lasers and attuned sensors. Advanced LIGO will by 2020 become 1000 times more likely than its predecessor to detect gravitational waves.

    “We’ll be able to see well beyond the local group, up to 300 megaparsecs away, which includes thousands of galaxies,” says Mario Diaz, a professor at the University of Texas at Brownsville and director of the Center for Gravitational Wave Astronomy. ”That’s the reason why pretty much everyone agrees if gravitational waves exist then Advanced LIGO has to see them.”

    Eventually joining LIGO in its attempt to catch a gravitational wave will be the VIRGO Interferometer at the European Gravitational Observatory in Italy and the Kamioka Gravitational Wave Detector at the Kamioka Mine in Japan. VIRGO started its search in 2007 and is currently undergoing upgrades. KAGRA is expected to begin operations in 2018. By the time KAGRA comes online, all three instruments should have similar levels of sensitivity.

    Advanced LIGO

    LIGO is made up of two identical laser interferometers, one in Louisiana and the other in Washington.

    ligo
    Courtesy of LIGO Laboratory

    At a laser interferometer, scientists take a single, powerful laser beam and split it in two. The two beams then travel down two equally long tunnels. At the end of each tunnel, each beam hits a mirror and reflects back.

    The tunnels are perpendicular to one another, creating a giant “L.” Because of this, the reflected beams return to the same spot and cancel each other out. That is, unless a gravitational wave intervenes.

    inter
    The light path through a Michelson interferometer. The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the three mirrors.

    If a gravitational wave passes through, it will distort the fabric of spacetime in which the observatory sits. This will warp the physical distance between the mirrors, giving one of the laser beams the advantage in reaching its final destination first. Because the beams will not cancel one another out, they will produce a signal in the detector.

    Advanced LIGO isn’t any bigger than LIGO, says Fred Raab of Caltech, head of the LIGO Hanford Observatory. Scientists are transforming the experiment from the inside. “That was part of the strategy for building LIGO… it’s the upgrades to technology that really counts.”

    The impressive part, says Gabriela Gonzalez, LIGO spokesperson and professor at Louisiana State University, is the miniscule size of the change in distance and the technology’s capability to detect it.

    “The [tunnels] are 4 kilometers long, and we have sensitivities to about 10-18 meters,” Gonzalez says. “We can tell how 4 kilometers one way differs from 4 kilometers the other way by a change that is a thousandth the size of a proton diameter.”

    Scientists built two identical machines 1865 miles apart because the wavelength of the gravitational waves they’re looking for should be about that long; if they measure the same signal in both detectors simultaneously, it will be a good indication that the signature is genuine.

    One of the new features of Advanced LIGO will be an additional mirror that will enable scientists to enhance sensitivity to different frequencies of gravitational waves. With different frequencies come different levels of spacetime distortion and hence different changes in the distance between the two mirrors. The different signals will tell scientists something about the properties of gravitational waves and their sources.

    “The extra mirror allows us to apply a boost in sensitivity to a smaller range of frequencies in the search band,” Raab says. “It works kind of like the treble/bass adjustment in your car stereo. You still hear the music, but with different frequencies enhanced.”

    Straight to the source

    Scientists at Advanced LIGO would like to identify the sources of gravitational waves.

    They most likely come from binary neutron stars like the one Hulse and Taylor discovered. But they could also originate in systems that right now exist only in theory, such as black hole binaries and neutron star-black hole binary systems.

    Christopher Berry, a research fellow at the University of Birmingham, is part of a team that is designing a way to quickly estimate where in the sky the source of a gravitational wave might originate in order to share that information with astronomers around the world, who could take a closer look.

    “You can analyze the data to determine quantities like mass, orientation and location,” he says. “One of the things we want to do with parameter estimation is quickly estimate where in the sky a source came from and then tell people with telescopes to point there.”

    Gravitational waves could also come from the same systems that produce gamma-ray bursts, the brightest known electromagnetic events in the universe. Scientists think that gamma-ray bursts may come from merging binary neutron stars, a hypothesis LIGO could investigate.

    Determining a link between gamma-ray bursts and binary neutron stars would be one outstanding achievement for Advanced LIGO, but the future observatory has potential for more, Berry says.

    “We can see inside the sun using neutrinos, and gravitational waves are yet another way to look at the universe,” he says. “We can make discoveries we weren’t expecting.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 12:56 pm on October 3, 2014 Permalink | Reply
    Tags: , , , , , , , Particle Physics,   

    From FNAL- “Frontier Science Result: CMS Subatomic hydrodynamics” 


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

    Friday, Oct. 3, 2014
    This column was written by Don Lincoln
    FNAL Don Lincoln
    Dr. Don Lincoln

    It’s hard for most people to imagine what it’s like at the heart of a particle collision. Two particles speed toward one another from opposite directions and their force fields intertwine, causing some of the particles’ constituents to be ejected. Or possibly the energy embodied in the interaction might be high enough to actually create matter and antimatter. It’s no wonder the whole process seems confusing.

    crash
    The same basic equations that govern the flow of water are important for describing the collisions of lead nuclei. In today’s article, we’ll get a glimpse of how this works.

    Things get a little easier to imagine when the particles are the nuclei of atoms (note that I said easier, not easy). For collisions between two nuclei of lead, one can imagine two small spheres, each containing 208 protons and neutrons, coming together to collide. Depending on the violence of the collision, some or many of the protons and neutrons might figuratively melt, releasing their constituent quarks so they can scurry around willy-nilly. Physicists call this form of matter a quark-gluon plasma, and it acts much like a liquid.

    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

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

    Part of this liquid-like behavior is due to the fact that so many particles are involved. An LHC collision between two lead nuclei might involve thousands or tens of thousands of particles. Because these particles are quarks and gluons, they experience the strong nuclear force. So as long as they are close enough to each other, the particles interact strongly enough that they clump a bit together. The net outcome is that the flow of particles from collision between lead nuclei looks vaguely like splashes of water. In these cases, the equations of hydrodynamics apply. Mathematical descriptions like these have been used to make sense of other features we see in LHC collisions between lead nuclei.

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

    However, there is more to understand. We can imagine collisions between the collective 416 protons and neutrons of lead nuclei as splashes of water, but when a pair of protons collide, the collision doesn’t yield enough particles to exhibit hydrodynamic behavior. So as the number of particles involved goes down, the “splash” behavior must slowly go away. In addition, in the first studies of lead nuclei collisions, only the grossest features of the collision were studied. This is because it is impossible to identify individual quarks and gluons.

    There are ways to dig into these sorts of questions. One way is to look at collisions in which one beam is a proton and the other is a lead nucleus. This is a halfway point between the usual LHC proton-proton collisions and the lead-lead ones. In addition, we can turn our attention to quarks that we can unambiguously identify, such as bottom, charm and strange quarks, to better understand the hydrodynamic behavior.

    In this study, physicists looked at particles containing strange quarks. Since strange quarks don’t exist in the beam protons, studying them gives a unique window into the dynamics of lead-lead collisions. By combining studies of particles with strange quarks in lead-lead and lead-proton collisions, scientists hope to better understand the complicated and liquid-like behavior that is just beginning to reveal its secrets.

    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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