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  • richardmitnick 1:23 pm on February 2, 2016 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From CERN: “The story of ALICE” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    01 February 2016
    Iva Raynova

    The discussions about the future of heavy-ion physics at CERN started in 1986, even before the building of the Large Electron-Positron Collider (LEP) had been completed. Four years later the idea of creating a dedicated heavy-ion detector for the Large Hadron Collider was born and on 13 December 1990 the Heavy Ion Proto Collaboration (HIPC) held its first meeting. Later on, during the historic Evian meeting Towards the LHC experimental programme in 1992, the expression of interest to create ALICE was submitted, followed by the letter of intent in 1994 and by the technical proposal in 1995.

    CERN ALICE Icon HUGE

    One of the people, responsible for the creation of ALICE, is Jurgen Schukraft. Spokesperson of the collaboration for the first 20 years of its existence, he is also the person who organised the initial meeting of HIPC. In the following interview we will try to show you the evolution of ALICE through his eyes.

    Has ALICE changed much since the beginning?

    Jurgen: In the beginning, the plan for the experiment was different from what it eventually turned out to be. We had a big TPC, we had a silicon vertex detector, we had time of flight, but the magnet was completely different. Ever since we sent the letter of intent, we had many different ideas. All the details were missing and we made a lot of additions afterwards, but the essential part of the detector was already decided by 1992.

    AliceDetectorLarge
    ALICE Detector

    In terms of the collaboration, it was very different at the time, because most of the people at CERN were doing experiments at low energies – the LEP programme at CERN. The Large Hadron Collider was still far in the future. It was after the approval of the technical proposal in 1994 when we started some serious research and development. In 1998, when the SPS experiment stopped, more people joined our collaboration.

    Which are the most interesting discoveries, made in ALICE?

    Jurgen: We have made many discoveries so far, but one thing which we did not expect is that each of these little “big bangs” has its own character. These explosions are so strong that every one of them is different and individual. This couldn’t be observed in the other types of collisions, where we only look at the average properties of the particles.

    The other very interesting thing for me is the discovery that there is a much deeper connection between all the QCD processes – everything which involves strong interaction – they are much [more] deeply connected than we originally thought.

    I think it would be very good if in the next 10 or 15 years we manage to embed what we have learned from the heavy-ion physics into the bigger context of the standard model.

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

    Are you happy with how the experiment developed?

    Jurgen: I think overall it worked out as well as we could have hoped. The physics at the LHC turned out to be extremely interesting. Even more interesting than we initially thought. Also, the experiment worked very well. There are always things that could be done better, but we constantly learn. That is why ALICE is going to be upgraded during the next long shutdown.

    In addition, more people came to the collaboration than we thought would join. There are currently about 1500 members. In these terms we developed even better than I hoped. I am pleased and also proud of our community and of the fact that we managed to create such a huge experiment.

    We were a bit naive in the beginning, thinking that 10-12 years were going to be enough to do what eventually took us 20 years. A bit naive, but also very enthusiastic. What I am happy about is that we didn’t have big disappointments along the way. On the contrary – we had a very satisfactory development. This project was more complicated, more expensive and much bigger than what we had done before. It was a big mountain to climb and I am proud that we managed to get to the top.

    See the full article here.

    Please help promote STEM in your local schools.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 2:28 pm on January 20, 2016 Permalink | Reply
    Tags: Accelerator Science, , Heavy-Ion run, ,   

    From CERN: “LHC surpasses design luminosity with heavy ions” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    Jan 15, 2016
    John Jowett

    The LHC has finished 2015 with a successful heavy-ion run. For the first time, the lead nuclei have collided with an average centre-of-mass energy per pair of nucleons of 5.02 TeV.

    Temp 1
    First events

    The extensive modifications made to the LHC during its first long shutdown allowed the energy of the proton beams to be increased from 4 TeV in 2012 to 6.5 TeV, enabling proton–proton collisions at a centre-of-mass energy of 13 TeV, in 2015. As usual, a one-month heavy-ion run was scheduled at the end of the year. With lead nuclei colliding, the same fields in the LHC’s bending magnets would have allowed 5.13 TeV per colliding nucleon pair. However, it was decided to forego the last whisker of this increase to match the equivalent energy of the proton–lead collisions that took place in 2013, namely 5.02 TeV. Furthermore, the first week of the run was devoted to colliding protons at 2.51 TeV per beam. This will allow the LHC experiments to make precise comparisons of three different combinations of colliding particles, p–p, p–Pb and Pb–Pb, at the same effective energy of 5.02 TeV. This is crucial to disentangling the ascending complexity of the observed phenomena (CERN Courier March 2014 p17).

    The first (and last, until 2018) Pb–Pb operation close to the full energy of the LHC was also the opportunity to finally assess some of its ultimate performance limits as a heavy-ion collider. A carefully targeted set of accelerator-physics studies also had to be scheduled within the tight time frame.

    Delivering luminosity

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

    Planning for the recommissioning of the LHC to run in two different operational conditions after the November technical stop resembled a temporal jigsaw puzzle, with alternating phases of proton and heavy-ion set-up (the latter using proton beams at first) continually readapted to the manifold constraints imposed by other activities in the injector complex, the strictures of machine protection, and the unexpected. For Pb–Pb operation, a new heavy-ion magnetic cycle was implemented in the LHC, including a squeeze to β* = 0.8 m, together with manipulations of the crossing angle and interaction-point position at the ALICE experiment. First test collisions occurred early in the morning of 17 November, some 10 hours after first injection of lead.

    The new Pb–Pb energy was almost twice that of the previous Pb–Pb run in 2011, and some 25 times that of RHIC at Brookhaven, extending the study of the quark–gluon plasma to still-higher energy density and temperature. Although the energy per colliding nucleon pair characterises the physical processes, it is worth noting that the total energy packed into a volume on the few-fm scale exceeded 1 PeV for the first time in the laboratory.

    After the successful collection of the required number of p–p reference collisions, the Pb–Pb configuration was validated through an extensive series of aperture measurements and collimation-loss maps. Only then could “stable beams” for physics be declared at 10.59 a.m. on 25 November, and spectacular event displays started to flow from the experiments.

    Temp 2
    Beam-loss monitor signals

    In the next few days, the number of colliding bunches in each beam was stepped up to the anticipated value of 426 and the intensity delivered by the injectors was boosted to its highest-ever values. The LHC passed a historic milestone by exceeding the luminosity of 1027 cm–2 s–1, the value advertised in its official design report in 2004.

    This allowed the ALICE experiment to run in its long-awaited saturated mode with the luminosity levelled at this value for the first few hours of each fill.

    Soon afterwards, an unexpected bonus came from the SPS injection team, who pulled off the feat of shortening the rise time of the SPS injection kicker array, first to 175 ns then to 150 ns, allowing 474, then 518, bunches to be stored in the LHC. The ATLAS and CMS experiments were able to benefit from luminosities over three times the design value. A small fraction of the luminosity in this run was delivered to the LHCb experiment, a newcomer to Pb–Pb collisions.
    Nuclear beam physics

    The electromagnetic fields surrounding highly charged ultrarelativistic nuclei are strongly Lorentz-contracted into a flat “pancake”. According to the original insight of Fermi, Weizsäcker and Williams, these fields can be represented as a flash of quasi-real photons. At LHC energies, their spectrum extends up to hundreds of GeV. In a very real sense, the LHC is a photon–photon and photon–nucleus collider (CERN Courier November 2012 p9). The study of such ultraperipheral (or “near-miss”) interactions, in which the two nuclei do not overlap, is an important subfield of the LHC experimental programme, alongside its main focus on the study of truly nuclear collisions.

    From the point of view of accelerator physics, the ultraperipheral interactions with their much higher cross-sections loom still larger in importance. They dominate the luminosity “burn-off”, or rate at which particles are removed from colliding beams, leading to short beam and luminosity lifetimes. Furthermore, they do so in a way that is qualitatively different from the spray of a few watts of “luminosity debris” by hadronic interactions. Rather, the removed nuclei are slightly modified in charge and/or mass, and emerge as new, well-focussed, secondary beams. These travel along the interaction region just like the main beam but, as soon as they encounter the bending magnets of the dispersion-suppressor section, their trajectories deviate, as in a spectrometer.

    The largest contribution to the burn-off cross-section comes from the so-called bound-free pair-production (BFPP) in which the colliding photons create electron–positron pairs with the electron in a bound-state of one nucleus. A beam of these one-electron ions, carrying a power of some tens of watts, emerges from the interaction point and is eventually lost on the outer side of the beam pipe.
    Controlled quench

    The LHC operators have become used to holding their breath as the BFPP loss peaks on the beam-loss monitors rise towards the threshold for dumping the beams (figure). There has long been a concern that the energy deposited into superconducting magnet coils may cause them to quench, bringing the run to an immediate halt and imposing a limit on luminosity. In line with recent re-evaluations of the magnet-quench limits, this did not happen during physics operation in 2015 but may happen in future operation at still-higher luminosity. During this run, mitigation strategies to move the losses out of the magnets were successfully implemented. Later, in a special experiment, one of these bumps was removed and the luminosity slowly increased. This led to the first controlled steady-state quench of an LHC dipole magnet with beam, providing long-sought data on their propensity to quench. On the last night of the run, another magnet quench was deliberately induced by exciting the beam to create losses on the primary collimators.

    Photonuclear interactions also occur at comparable rates in the collisions and in the interactions with the graphite of the LHC collimator jaws. Nuclei of 207Pb, created by the electromagnetic dissociation of a neutron from the original 208Pb at the primary collimators, were identified as a source of background after traversing more than a quarter of the ring to the tertiary collimators near ALICE.

    These, and other phenomena peculiar to heavy-ion operation, must be tackled in the quest for still-higher performance in future years.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New

    LHC

    CERN LHC New
    CERN LHC Grand Tunnel

    LHC particles

    Quantum Diaries

     
  • richardmitnick 9:03 pm on December 28, 2015 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From DESY: “ERC Starting Grant for characterising the Higgs boson” 

    DESY
    DESY

    2015/12/28
    No writer credit found

    Temp 1
    No image credit found

    Kerstin Tackmann, a physicist at DESY, is to receive over 1.3 million euros from the European Research Council (ERC) in order to carry out research aimed at a more detailed characterisation of the Higgs boson.

    CERN ATLAS Higgs Event
    Higgs event at ATLAS

    She will use a starting grant to set up a research group to investigate the properties of the Higgs boson in great detail, as part of the international ATLAS Collaboration.

    CERN ATLAS New
    ATLAS

    These measurements are an important step towards identifying whether the particle fits the Standard Model of particle physics. The 5-year project is scheduled to begin in 2016.

    Ever since particle physicists working on the big LHC experiments ATLAS and CMS announced, in 2012, the discovery of a particle whose properties corresponded to those of the elusive Higgs boson, particle physics has faced an extremely exciting mystery: does this Higgs boson fit the Standard Model of particle physics, the currently accepted description of the elementary particles that make up matter and the forces acting between them, or will it open the path to a new, higher-level theory.

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

    CERN CMS Detector
    CMS

    CERN CMS Event
    CMS Higgs event

    Standard model with Higgs New
    Standard Model of Particle Physics

    Using the data available so far, scientists have already been able to determine the particle’s mass of around 125 gigaelectronvolts (GeV) and its spin of zero to a fairly high degree of accuracy. To obtain even more precise information about additional properties of the particle, the researchers need to analyse far more data from proton-proton collisions in the LHC. They are particularly interested in finding out exactly how the Higgs field, of which the Higgs boson is an indication, lends elementary particles their mass. To answer this question, they have started to analyse the collision data from “LHC Run 2”, which began this summer and which is expected to produce about 15 times as many Higgs bosons as the LHC’s previous run. The analysis of this large amount of collision data will allow far more reliable conclusions to be drawn.

    Kerstin Tackmann intends to devote herself to these questions together with two post-docs and three PhD students, and will be analysing the collisions from Run 2 of the ATLAS detector in great detail. They will be working as part of the ATLAS Collaboration, involving hundreds of scientists from all over the world. Her group is going to concentrate on measuring the kinematic properties of Higgs boson production. The focus will lie especially on the decay of the Higgs boson into two photons or four leptons, which allows very accurate measurements to be made. This is where deviations from the precise predictions of the Standard Model could occur, should the Higgs boson not fit the Standard Model.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

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

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

    Nature Mag
    Nature

    22 December 2015
    Elizabeth Gibney

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    Nature doi:10.1038/nature.2015.19040

    See the full article here .

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

     
  • richardmitnick 4:49 pm on December 22, 2015 Permalink | Reply
    Tags: Accelerator Science, , CEBAF,   

    From JLab: “Jefferson Lab Accelerator Delivers Its First 12 GeV Electrons” 

    December 21, 2015
    Kandice Carter, Jefferson Lab Public Affairs
    757-269-7263
    kcarter@jlab.org

    1
    On December 14, full-energy 12 GeV electron beam was provided for the first time, to the Experimental Hall D complex, located in the upper, left corner of this aerial photo of the Continuous Electron Beam Accelerator Facility. Hall D is the new experimental research facility – added to CEBAF as part of the 12 GeV Upgrade project. Beam was also delivered to Hall A (dome in the lower left).

    The newly upgraded accelerator at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility has delivered full-energy electrons as part of commissioning activities for the ongoing 12 GeV Upgrade project. At 4:20 p.m. on Monday, Dec. 14, operators of the Continuous Electron Beam Accelerator Facility (CEBAF) delivered the first batch of 12 GeV electrons (12.065 GeV) to its newest experimental hall complex, Hall D.

    “Through part of the ongoing upgrade process, we have refurbished or replaced virtually every one of the many thousands of components in CEBAF,” said Allison Lung, deputy project manager for the CEBAF 12 GeV Upgrade project and Jefferson Lab assistant director. “Now, to see the machine already reaching its top design energy – It’s a testament to the hard work of the many Jefferson Lab staff members who have made it possible.”

    The 12 GeV Upgrade project, which is scheduled to be completed in September 2017, was designed to enable the machine to provide 12 GeV electrons, which is triple its original design and double its maximum operational energy before the upgrade. By increasing the energy of the electrons, scientists are increasing the resolution of the CEBAF microscope for probing ever more deeply into the nucleus of the atom. The $338 million upgrade entails adding ten new acceleration modules and support equipment to CEBAF, as well as construction of a fourth experimental hall, upgrades to instrumentation in the existing halls, and other upgrade components.

    “The CEBAF accelerator commissioning and achievement of the design energy required hard work, patience and teamwork,” said Arne Freyberger, Jefferson Lab’s director of accelerator operations. “It’s just fantastic to watch it all come together, and the sense of accomplishment is palpable.”

    Once the upgrade is complete, CEBAF will become an unprecedented tool for the study of the basic building blocks of the visible universe. It will be able to deliver 11 GeV electrons into its original experimental areas, Halls A, B and C for experiments. The full-energy, 12 GeV electrons are now being provided to the Experimental Hall D complex to initiate studies of the force that glues matter together. In Hall D, scientists hope to produce new particles, called hybrid mesons. Hybrid mesons are made of quarks bound together by the strong force, the same building blocks of protons and neutrons, but in hybrid mesons, this force is somewhat modified. It’s hoped that observing these hybrid mesons and revealing their properties will offer a new window into the inner workings of matter.

    “This kind of science explores the most fundamental mysteries: Why are we here? Why is it that one particular combination of quarks and forces takes on that material property, while a different combination of quarks and forces makes up the human body?” Lung said. “One particularly compelling question that scientists have had, is why do we always find quarks bound together in two and threes, but never alone? We will have an entirely unique facility designed to answer the question.”

    Jefferson Lab is a world-leading nuclear physics research laboratory devoted to the study of the building blocks of matter inside the atom’s nucleus – quarks and gluons – that make up 99 percent of the mass of our visible universe. Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

    DOE’s 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, visit science.energy.gov.

    See the full article here .

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    Thomas Jefferson National Accelerator Facility is managed by Jefferson Science Associates, LLC for the U.S. Department of Energy

     
  • richardmitnick 8:11 pm on December 21, 2015 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From DESY: “First electrons accelerated in European XFEL” 

    DESY
    DESY

    2015/12/21
    No Writer Credit

    1
    View into the injector area of European XFEL. The yellow tube is the first superconducting accelerator module (Photo: Dirk Nölle, DESY).

    A crucial component of the European XFEL has taken up operation: The so-called injector, the 45-metre long first part of the superconducting particle accelerator, has accelerated its first electrons to nearly the speed of light. This is the first beam ever accelerated at the European XFEL and represents a major advancement toward the completion of the facility.

    The X-ray laser European XFEL is an international research facility in northern Germany that will produce ultrabright X-ray laser flashes for unprecedented studies of the nanocosmos. It consists of a 2-kilometre long superconducting linear electron accelerator, followed by a series of highly precise magnets to produce the highly brilliant X-ray laser light.

    The injector, which is located on the DESY campus in Hamburg and has been under construction since 2013, produced a series of tightly packed sets of electrons, or bunches, that passed through the 45-metre long injector beamline. The electrons made the full trip from start to end of the injector in 0.15 microseconds, achieving near light speed.

    The injector shapes the highly charged electron bunches and gives them their initial energy, which is gradually increased across a 2-kilometre long linear accelerator that is still being assembled. Once energized, the electrons will be ready to generate the facility’s X-ray flashes, enabling scientists to perform studies that are expected to have large impacts on medicine, energy production and storage, materials research, and many other fields.

    DESY, which is European XFEL’s main shareholder and close partner, is responsible for the construction and operation of the electron injector as well as the rest of the linear accelerator. Components for the injector were produced across Europe by the 17-institute European XFEL Accelerator Consortium, which is led by DESY. This includes work done by DESY as well as in-kind contributions from institutes in France, Italy, Poland, Russia, Spain, Sweden, and Switzerland.

    XFEL Gun
    The ‘gun’ releases the electrons and accelerates them shaped in bunches (Photo: Dirk Nölle, DESY).

    “All members of the European XFEL Accelerator Consortium contributed to the injector, and we appreciate their professionalism during design, construction, and installation,” says DESY leading scientist Dr. Hans Weise, who is coordinator for the Accelerator Consortium. “Their contributions now allow us to prepare the high-quality electron beam required for operation of the free-electron laser.”

    The design of the injector is strongly based on the one found in DESY’s X-ray free-electron laser FLASH, the prototype facility for the European XFEL that began operation as a user facility in 2005.

    DESY FLASH
    DESY FLASH

    Several billion electrons are released from an electrode of caesium telluride when it is struck by an intense ultraviolet laser flash. The electrons form a bunch which is accelerated by radio frequency and kept together by intense magnetic fields. The bunch is accelerated, first through a normal conducting cavity made of copper, then through a pair of superconducting accelerator cryomodules. The two latter devices are chilled to -271°C by liquid helium to allow for highly efficient beam acceleration. These modules give the full electron beam the required characteristics needed for producing the X-ray flashes that will be used for researching matter at the atomic scale.

    The injector will continue to go through rigorous testing while the rest of the linear accelerator is installed. The next major milestone will be accelerating electrons the for the full accelerator length to the European XFEL’s Osdorfer Born site approximately 2.1 km away from the start of the injector.

    XFEL Campus
    XFEL map

    This is expected in late 2016, with user operation to follow in 2017.

    XFEL Tunnel
    View into the main accelerator tunnel of European XFEL, where 100 superconducting accelerator modules are being installed (Photo: Dirk Nölle, DESY).

    “The first electrons in the injector mark a major milestone for this ambitious discovery machine – my congratulations go to the physicists and engineers who have constructed and installed the components with great dedication,” says Prof. Helmut Dosch, chairman of the DESY Board of Directors. “And with more than half of the superconducting modules of the main accelerator tested and installed, I am sure that the start of the commissioning of the European XFEL accelerator will follow soon.”

    “I am glad to see the efforts with constructing the injector come to a successful completion, as we continue our focus on finishing the rest of the accelerator so we can provide researchers with the world’s brightest X-ray light,” says Prof. Massimo Altarelli, managing director of European XFEL. “I want to thank everyone involved in the construction and start-up of this starting point for our facility.”

    See the full article here .

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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 2:19 pm on December 18, 2015 Permalink | Reply
    Tags: Accelerator Science, , , , , , ,   

    From Symmetry: “CERN and US increase cooperation” 

    Symmetry

    12/18/15
    Sarah Charley

    1
    Eric Bridiers, US Mission

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

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

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

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

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

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

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

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

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

    CERN ATLAS New
    ATLAS

    CMS Use this one
    CMS

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

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

    CERN ALICE New
    ALICE

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

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

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

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

    FNAL Dune & LBNF
    DUNE

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

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

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

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:29 pm on December 16, 2015 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From CERN: “ATLAS and CMS present their 2015 LHC results” 

    Cern New Bloc

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    16 Dec 2015
    Corinne Pralavorio

    1
    A 13 TeV collision recorded by ATLAS. The yellow and green bars indicate the presence of particle jets, which leave behind lots of energy in the calorimeters. (Image: ATLAS)

    2
    A 13 TeV proton collision recorded by CMS. The two green lines show two photons generated by the collision. (Image: CMS)

    Particles circulated in the Large Hadron Collider (LHC) on Sunday for the last time in 2015, and, two days later, the two large general-purpose experiments, ATLAS and CMS, took centre stage to present their results from LHC Run 2. These results were based on the analysis of proton collisions at the previously unattained energy of 13 TeV, compared with the maximum of 8 TeV attained during LHC Run 1 from 2010 to 2012.

    The amount of data on which the two experiments’ analyses are based is still limited – around eight times less than that collected during Run 1 – and physicists need large volumes of data to be able to detect new phenomena. Nonetheless, the experimentalists have already succeeded in producing numerous results. Each of the two experiments has presented around 30 analyses, about half of which relate to Beyond-Standard-Model research. The Standard Model is the theory that describes elementary particles and their interactions, but it leaves many questions unanswered. Physicists are therefore searching for signs of Beyond-Standard-Model physics that might help them to answer some of those questions.

    The new ATLAS and CMS results do not show any significant excesses that could indicate the presence of particles predicted by alternative models such as supersymmetry. The two experiments have therefore established new limits for the masses of these hypothetical new particles. Advances in particle physics often come from pushing back these limits. For example, CMS and ATLAS have established new restrictions for the mass of the gluino, a particle predicted by the theory of supersymmetry. This is just one of the many results that were presented on 15 December.

    The two experiments have also observed a slight excess in the diphoton decay channel. Physicists calculate the mass of hypothetical particles that decay to form a pair of photons, and look at how often different masses are seen. If the distribution does not exactly match that expected from known processes, or in other words a bump appears at a specific mass not corresponding to any known particle, it may indicate a new particle being produced and decaying. However, the excess is too small at this stage to draw such a conclusion. We will have to wait for more data in 2016 to find out whether this slight excess is an inconsequential statistical fluctuation or, alternatively, a sign of the existence of a new phenomenon. Find out next time: season 2 is only just beginning.

    The presentations by ATLAS and CMS are available here.

    See the full article here.

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  • richardmitnick 8:11 pm on December 16, 2015 Permalink | Reply
    Tags: Accelerator Science, , , , , , ,   

    From Pauline Gagnon at Quantum Diaries: “If, and really only if…” 

    12.16.15

    Pauline Gagnon
    Pauline Gagnon

    On December 15, at the End-of-the-Year seminar, the CMS and ATLAS experiments from CERN presented their first results using the brand new data accumulated in 2015 since the restart of the Large Hadron Collider (LHC) at 13 TeV, the highest operating energy so far.

    CERN CMS Detector
    CMS

    CERN ATLAS New
    ATLAS

    CERN LHC Map
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    LHC

    Although the data sample is still only one tenth of what was available at lower energy (namely 4 fb-1 for ATLAS and 2.8-1 fb for CMS collected at 13 TeV compared to 25 fb-1 at 8 TeV for each experiment), it has put hypothetical massive particles within reach. If the LHC were a ladder and particles, boxes hidden on shelves, operating the LHC at higher energy is like having a longer ladder giving us access to higher shelves, a place never checked before. ATLAS and CMS just had their first glimpse at it.

    Both experiments showed how well their detectors performed after several major improvements, including collecting data at twice the rate used in 2012. The two groups made several checks on how known particles behave at higher energy, finding no anomalies. But it is in searches for new, heavier particles that every one hopes to see something exciting. Both groups explored dozens of different possibilities, sifting through billions of events.

    Each event is a snapshot of what happens when two protons collide in the LHC. The energy released by the collision materializes into some heavy and unstable particle that breaks apart mere instants later, giving rise to a mini firework. By catching, identifying and regrouping all particles that fly apart from the collision point, one can reconstruct the original particles that were produced.

    Both CMS and ATLAS found small excesses when selecting events containing two photons. In several events, the two photons seem to come from the decay of a particle having a mass around 750 GeV, that is, 750 times heavier than a proton or 6 times the mass of a Higgs boson.

    CERN ATLAS Higgs Event
    Higgs event at ATLAS

    Since the two experiments looked at dozens of different combinations, checking dozens of mass values for each combination, such small statistical fluctuations are always expected.

    2
    Top part: the combined mass given in units of GeV for all pairs of photons found in the 13 TeV data by ATLAS. The red curve shows what is expected from random sources (i.e. the background). The black dots correspond to data and the lines, the experimental errors. The small bump at 750 GeV is what is now intriguing. The bottom plot shows the difference between black dots (data) and red curve (background), clearly showing a small excess of 3.6σ or 3.6 times the experimental error. When one takes into account all possible fluctuations at all mass values, the significance is only 2.0σ

    What’s intriguing here is that both groups found the same thing at exactly the same place, without having consulted each other and using selection techniques designed not to bias the data. Nevertheless, both experimental groups are extremely cautious, stating that a statistical fluctuation is always possible until more data is available to check this with increased accuracy.

    3
    CMS has slightly less data than ATLAS at 13 TeV and hence, sees a much smaller effect. In their 13 TeV data alone, the excess at 760 GeV is about 2.6σ, 3σ when combined with the 8 TeV data. But instead of just evaluating this probability alone, experimentalists prefer take into account the fluctuations in all mass bins considered. Then the significance is only 1.2σ, nothing to write home about. This “look-elsewhere effect” takes into account that one is bound to see a fluctuation somewhere when ones look in so many places.

    Theorists show less restrain. For decades, they have known that the Standard Model, the current theoretical model of particle physics, is flawed and have been looking for a clue from experimental data to go further.

    4
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Many of them have been hard at work all night and eight new papers appeared this morning, proposing different explanations on which new particle could be there, if something ever proves to be there. Some think it could be a particle related to Dark Matter, others think it could be another type of Higgs boson predicted by Supersymmetry or even signs of extra dimensions. Others offer that it could only come from a second and heavier particle. All suggest something beyond the Standard Model.

    Two things are sure: the number of theoretical papers in the coming weeks will explode. But establishing the discovery of a new particle will require more data. With some luck, we could know more by next Summer after the LHC delivers more data. Until then, it remains pure speculation.

    This being said, let’s not forget that the Higgs boson made its entry in a similar fashion. The first signs of its existence appeared in July 2011. With more data, they became clearer in December 2011 at a similar End-of-the-Year seminar. But it was only once enough data had been collected and analysed in July 2012 that its discovery made no doubt. Opening one’s gifts before Christmas is never a good idea.

    See the full article here .

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  • richardmitnick 7:33 am on December 12, 2015 Permalink | Reply
    Tags: Accelerator Science, , , LHC Run 2   

    From ATLAS at CERN: “Photo Essay: Impressions from the Control Room” 

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    CERN

    June 12, 2015 [This just became available]
    Abha Eli Phoboo

    As final preparations were made for the start of the Large Hadron Collider’s (LHC) Run 2, the ATLAS Control Room was the centre of activity. Here are images from the three days that were landmark events — first collisions at 900 GeV on 5 May, first test collisions at 13 TeV on 20 May , and 3 June that marked the beginning of physics data-taking at 13 TeV and ATLAS’ journey into unexplored frontiers of physics.

    1
    5 May: Physicists in the ATLAS Control Room prepare for the first scheduled proton beam collisions to be delivered by the Large Hadron Collider. The beams collided at injection energy or 900 GeV (one proton has a mass of about 1 GeV). IMAGE: Silvia Biondi/The ATLAS Experiment

    2
    5 May: ATLAS people on shift that morning wait for the LHC Control Room to signal injection of beam. IMAGE: Silvia Biondi/The ATLAS Experiment

    Temp 1
    5 May: ATLAS Run Coordinator Alessandro Polini (left) shares a smile with Spokesperson Dave Charlton as they wait for 900 GeV collisions.
    IMAGE: Matteo Franchini/The ATLAS Experiment

    4
    5 May: The LHC beam being monitored on one of the many control room desktop monitors. IMAGE: Silvia Biondi/The ATLAS Experiment

    6
    5 May: A physicist on shift watches as the first collisions at injection energy or 900 GeV burst on the wall of screens in the ATLAS Control Room. IMAGE: Silvia Biondi/The ATLAS Experiment

    7
    6 May: Display of a proton collision event recorded by ATLAS at 900 GeV or injection energy. Tracks are reconstructed from hits in the inner tracking detector, including the new innermost pixel detector layer, the Insertable B-Layer. No image credit.

    8
    On 20 May, at 22:24, ATLAS recorded the first 13 TeV test collisions delivered by the Large Hadron Collider. The proton collisions set a new high energy record. IMAGE: Heinz Pernegger/The ATLAS Experiment

    9
    21 May: Display of a proton collision event recorded by ATLAS at 13 TeV collision energy. Tracks reconstructed from hits in the inner tracking detector are shown to originate from two interaction points, indicating a pile-up event. No image credit.

    10
    3 June: Morning light shines of the mural of a simulated Higgs event perpendicular to the one of the ATLAS detector. This image was taken on the morning when physics data-taking was scheduled to start. The mural is painted on the building that houses the ATLAS Control Room. 100m directly below the building is the cavern where the ATLAS detector sits on the Swiss side of the LHC. IMAGE: Clara Nellist/The ATLAS Experiment

    11
    3 June: ATLAS physicists gather inside the Control Room to witness the start of the physics data taking at 13 TeV with the ATLAS detector. IMAGE: Silvia Biondi/The ATLAS Experiment

    12
    3 June: ATLAS Run Coordinator Alex Cerri and Central Trigger Processing expert Julian Glatzer looking at plots that describe proton bunch groups from the LHC. Each LHC orbit has around 3,564 proton bunches spaced at every 25 nanoseconds to fill the 27 km ring. IMAGE: Silvia Biondi/The ATLAS Experiment

    13
    3 June: Readying for that moment when ATLAS began recording 13 TeV collision data. IMAGE: Pierre Descombe/CERN

    14
    3 June: Display of a proton collision event recorded by ATLAS with first LHC stable beams at a collision energy of 13 TeV. Tracks reconstructed by the tracking detector are shown as light blue lines, and hits in the layers of the silicon tracking detector are shown as colored filled circles. The four inner layers are part of the silicon pixel detector and the four outer layers are part of the silicon strip detector. The layer closest to the beam, is the IBL. No image credit.

    15
    3 June: The Control Room bursts into applause as ATLAS begins recording data. IMAGE: Emma Ward/The ATLAS Experiment

    See the full article here.

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