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  • richardmitnick 8:51 pm on December 17, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From IceCube: “Designing the future of the IceCube Neutrino Observatory” 

    icecube
    IceCube South Pole Neutrino Observatory

    17 Dec 2014
    Sílvia Bravo

    The IceCube Neutrino Observatory is a successful and large scientific facility located near the Amundsen-Scott South Pole station in Antarctica. This observatory hosts IceCube, a cubic-kilometer deep-ice particle detector that is, so far, the largest ever built – and on the surface, IceTop, an extended air shower array.

    Completed in 2010, IceCube has recently discovered astrophysical neutrinos, revealing their potential to explore our universe at energies at the PeV scale and above, where most of the universe is opaque to high-energy photons. But the big questions remain unsolved: where do these neutrinos come from? How does nature accelerate particles to such extreme energies?

    Prof. Olga Botner, IceCube spokesperson and a physics professor at the University of Uppsala, and Prof. Francis Halzen, IceCube principal investigator and a professor at the University of Wisconsin–Madison, tell us about the plans for an upgrade to the IceCube Neutrino Observatory. As an extension of the current detector, it can be built in a few years and within an affordable budget, thanks to expertise acquired with IceCube.

    a
    Artistic view of the Antarctic surface around the South Pole station, showing the position of the 86 strings of sensors in IceCube and the possible grid of the next-generation detector. Image: J.Yang/IceCube Collaboration

    Q: What has IceCube accomplished so far?

    Olga Botner (O): IceCube is the world’s foremost neutrino observatory, which, after just two years of running in its final configuration, discovered neutrinos from outer space that have energies a billion times larger than those of neutrinos produced by our Sun and a thousand times larger than any produced on Earth with man-made accelerators. The discovery of this high-energy neutrino flux is a turning point for neutrino astronomy: a dream of 50 years ago on the verge of becoming reality.

    Francis Halzen (F): The high level of the observed neutrino flux implies that a significant fraction of the energy in the non-thermal universe, powered by the gravitational energy of compact objects from neutron stars to supermassive black holes, is generated in hadronic accelerators. This tells us that we are approaching exciting times when high-energy neutrinos will reveal new sources or provide new insight on the energy generation in known sources.

    But IceCube has also been a successful detector with respect to its technical development. We developed highly successful designs for transforming natural ice into a particle detector. The optimized methods for deploying and commissioning large volume detectors in ice can be used for a next-generation detector; minimal modifications will target improvements focused on modernization, efficiency, and cost savings.

    O: This is a very important point. The detector was built within the expected time frame, within budget, and with a performance at least a factor of two better than anticipated.

    Going back to physics, I should also add that IceCube has yielded many interesting results beyond neutrino astronomy. We are studying cosmic rays, looking for signatures of the annihilations of dark matter particles into neutrinos, and investigating the properties of the neutrinos themselves. We have published competitive results in all these areas.

    Q: Why do we need a next-generation IceCube detector?

    F: We all agree on the observed spectrum of neutrinos, there’s no doubt about the discovery, but independent analyses of IceCube data have produced only on the order of 100 astrophysical neutrino events in several years. These modest numbers of cosmic neutrinos limit the ability of IceCube to be an efficient tool for neutrino astronomy over the next decade. A next-generation detector will provide an unprecedented view of the high-energy universe, taking neutrino astronomy to new levels of discovery. It is likely to resolve the question of the origin of the cosmic neutrinos recently discovered.

    O: That’s right! IceCube’s discovery of extraterrestrial neutrinos has shown us that even a cubic-kilometer detector is not enough. To fully exploit the potential for neutrino astronomy, a much larger observatory is needed. We are already working on its design. The new detector has been named IceCube-Gen2.

    Q: Is it feasible and cost-effective to build an even bigger detector at the Pole?

    O: It sure is. The good news is that the successful deployment and running of IceCube demonstrates that we have mastered the technologies to construct and operate a detector in the deep ice. The drilling systems and the optical modules for the next-generation detector will closely follow the designs that have been proven to work well—with certain modifications to improve the overall performance. This makes us confident that a next-generation detector is not only feasible but can be built in a cost-effective manner, just like IceCube.

    F: We didn’t know this before IceCube, but now we have measured the extremely long photon absorption lengths in ice. This will allow the spacing between strings of light sensors to exceed 250 m in a future IceCube extension; i.e., the instrumented volume can rapidly grow without increasing the costs much. In fact, we can build a ten-cubic-kilometer IceCube-Gen2 telescope by roughly doubling the instrumentation already deployed. Thus, a tenfold increase in astrophysical neutrino detection rates could be achieved with a cost comparable to the current IceCube detector.

    Q: And what about the time scale of this project? Will we need to wait a long time to see new results?

    O: We are aiming at an expanded array instrumenting a volume of 10 km3 for the detection of high-energy neutrinos—but also at improving the low-energy performance through deployment of a densely instrumented infill detector, PINGU, targeting neutrino mass hierarchy as its prime goal. We believe that this new IceCube-Gen2 observatory can be built within seven years of obtaining funding.

    Q: Sounds like a plan. Who is leading this next-generation IceCube?

    F: The present plan is to build IceCube following a management strategy that was successful in delivering IceCube on time and on budget. The collaboration is rapidly expanding, both in the US and in Europe and Canada. We expect that a larger fraction of the cost will be carried by significant contributions from our foreign collaborators.

    O: Exactly. The high-energy array and PINGU are both envisioned as parts of an IceCube-Gen2 observatory. A new collaboration, including IceCube members and additional institutions, is now being formed. This IceCube-Gen2 collaboration will work to develop proposals in the US and abroad to secure funding. We hope that IceCube-Gen2 will become a flagship scientific project for NSF as well as for funding agencies abroad.

    o
    This image shows a simulated high-energy event of about 60 PeV in the proposed IceCube Gen2 detector. Image: IceCube Collaboration

    Q: Can other current or in-design experiments do better than IceCube-Gen2?

    F: Well, we have strong competitors. Early efforts for cubic-kilometer neutrino detectors focused on deep-water-based detectors, including DUMAND, Lake Baikal, and ANTARES. So far, there is no cubic-kilometer neutrino detector in deep water, but these experiments have paved the way toward the proposed construction of KM3NeT in the Mediterranean Sea and GVD in Lake Baikal.

    O: These new projects, GVD in Lake Baikal and KM3NeT in the Mediterranean, are presently in the prototyping or early construction phase. They will eventually provide a complementary view of the sky to that of an Antarctic observatory.

    Q: Should we expect IceCube-Gen2 to be as successful as IceCube? That may be the desire, but are there objective reasons to think so?

    O: The main one is that we already have established the existence of a flux of high-energy neutrinos. What we now need are substantial number of events to further characterize this flux in terms of energy spectrum, a possible energy cut-off, flavor composition, and provenance. We just need a larger detector to do this in a reasonable time. The higher event rates in a larger array will also improve the chances of correlating our neutrino events with observations by the new generation of high-energy gamma-ray telescopes and gravitational wave detectors, together charting the non-thermal universe.

    F: The larger samples of high-energy neutrinos with improved angular resolution and energy measurement will give us a detailed understanding of the source distribution. This sample will reveal an unobstructed view of the universe at energies at PeV and above. Those are unexplored wavelengths where most of the universe is opaque to high-energy photons. As Olga was mentioning, the operation of IceCube-Gen2 in coincidence with other telescopes and detectors will present totally novel opportunities for multimessenger astronomy and multiwavelength follow-up campaigns to obtain a truly complete picture of astrophysical sources.

    + Info IceCube-Gen2: A Vision for the Future of Neutrino Astronomy in Antarctica, IceCube Collaboration: M.G. Aartsen et al. arxiv.org/abs/1412.5106

    This white paper presents early studies toward a next-generation IceCube detector with the aim of instrumenting a 10 km3 volume of clear glacial ice at the South Pole and delivering an order of magnitude increase in astrophysical neutrino samples of all flavors.

    Read also a short description of IceCube-Gen2 on the IceCube w

    See the full article here.

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 1:16 pm on December 17, 2014 Permalink | Reply
    Tags: , , Neutrinos,   

    From FNAL: “Gaining support for new long-baseline neutrino experiment at Fermilab” 

    FNAL Home


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

    Wednesday, Dec. 17, 2014
    Rob Roser

    i
    Jim Strait, project director for Fermilab’s proposed long-baseline neutrino experiment, answers a question at the Dec. 12 meeting to form a new collaboration at Fermilab. Photo: Reidar Hahn

    On Dec. 5 and 12, many of the world’s neutrino scientists gathered at CERN and Fermilab, respectively, to learn about the newly proposed next-generation long-baseline neutrino oscillation experiment. These meetings were established to discuss a new letter of intent (LOI) for the experiment.

    m
    More than 150 people attended the collaboration-forming meeting at Fermilab on Dec. 12. Photo: Reidar Hahn

    The LOI, which is currently signed by more than 350 scientists from more than 100 institutions around the world, leverages the Fermilab neutrino facility to undertake an experiment at Sanford Underground Research Facility in South Dakota.

    Sanford Underground Research Facility Interior
    Sanford

    The two meetings were designed to be identical in content. Fermilab Director Nigel Lockyer kicked off both meetings with a historical overview as well as a high-level plan forward. Jim Strait, project director for the proposed long-baseline neutrino experiment, discussed the Fermilab facility and what is being offered. ICFA Neutrino Panel Chair Ken Long and I presented the LOI in our role to bring the world’s long-baseline neutrino community together, and Fermilab Deputy Director Joe Lykken summarized the current discussions on the international governance process. Lively panel discussions followed, giving attendees a chance to interact with the LOI authors and learn more about the proposal. Copies of the talks are online.

    People can find the current draft of the LOI and sign it from the website. The deadline to sign it prior to its presentation to the PAC[?] is Jan. 11, 2015.

    The next step in the formation of this new international collaboration is its first meeting, to be held at Fermilab from Jan. 22-23. It is open to anyone who is interested in joining this new scientific endeavor. Sergio Bertolucci, CERN director of research and the interim Institutional Board chair for the collaboration, has called the meeting and will announce the agenda in the coming weeks.

    See the full article here.

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    Fermilab Campus

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

     
  • richardmitnick 11:14 pm on December 13, 2014 Permalink | Reply
    Tags: ANITA III, , , , , Neutrinos, The Economist,   

    From The Economist: “Balloon with a view” 

    Economist
    The Economist

    Dec 6th 2014
    No Writer Credit

    MEET ANITA. Strictly, ANITA III—for she is the third iteration of the Antarctic Impulsive Transient Antenna. Her job, when she is launched sometime in the next few days, will be to float, suspended from a giant balloon, over Antarctica’s ice, in order to record radio waves which that ice is giving off. These radio waves are generated by neutrinos passing through the ice, making Antarctica the biggest neutrino-detection laboratory in the world.

    The particular neutrinos that ANITA seeks are of extremely high energy. Where they come from, no one knows—nor, strictly speaking, is it actually known that they exist, for ANITAs I and II, which were smaller devices, failed to find them. But theory says they should be there, generated in whatever giant explosions also create cosmic rays.

    Cosmic rays are high-velocity protons, sprinkled with a smattering of heavier atomic nuclei, that fly through space until they hit something such as Earth’s atmosphere, when they disintegrate into a shower of other particles. They have been known for a century, but their origin remains mysterious because, being electrically charged, their paths are bent by the galaxy’s magnetic field. That means the directions they come from do not point to whatever created them.

    Neutrinos, however, are electrically neutral, as their name suggests. Their paths should thus point back towards their origins. Neutrinos do not interact much with other sorts of matter, but when one of ultra-high energy does so, the result is a shower of particles travelling at speeds which exceed that of light in ice. An object travelling faster than light’s speed in the medium through which it is passing will generate electromagnetic waves. These are known, after their discoverer, as Cherenkov radiation. And it is pulses of radio-frequency Cherenkov radiation, the electromagnetic equivalent of a sonic boom, which ANITA is looking for.

    an
    Up, up and away!

    Once airborne under her balloon—an object made of cling-film-like plastic that, when fully inflated, will be a fifth of the size of a football stadium—ANITA will take advantage of the polar vortex, a wind in constant revolution around the pole.

    p
    A wavy polar vortex on January 5, 2014.

    She will fly at an altitude of 35-40km, which will mean her antennae can see 1.5m km2 of ice. Ultra-high-energy neutrinos travelling through the ice are thought to interact with it and produce Cherenkov radiation about once per century per km2, so an area of this size would be expected to yield about 40 bursts a day. ANITA will complete several laps of the continent, each lasting about 15 days. Then the balloon will be cut loose, and she will deploy a parachute and be guided back to the surface for re-use.

    Astrophysicists are not the only people rubbing their mittens together in expectation of the results of this experiment. The neutrinos ANITA is looking for are far more energetic than anything produced by the Large Hadron Collider, the world’s most powerful particle accelerator. That means they may obey hitherto unperceived extensions of the laws of physics. One possibility is that, among the Cherenkov-radiation-generating particles produced when a neutrino collides with the ice, there may be an occasional miniature black hole.

    That would be particularly exciting, because such black holes might themselves disintegrate in a characteristic puff of radiation named after another physicist, Stephen Hawking. If Hawking radiation exists, it means black holes are not truly black—a discovery which would almost certainly win Dr Hawking a Nobel prize.

    Though it is not designed to search for Hawking radiation, ANITA would probably see it if it were there. And, since Hawking radiation is created, quite literally, out of nothing (the particles it is made from emerge from the vacuum of space and then steal the energy needed to become real from the black hole itself), that would assist understanding of a very strange piece of physics indeed.

    See the full article here.

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  • richardmitnick 4:30 pm on December 12, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From IceCube: “Drilling IceCube: a story of innovation, expertise and strong will “ 

    icecube
    IceCube South Pole Neutrino Observatory

    12 Dec 2014
    Silvia Bravo

    Building a cubic-kilometer telescope at the South Pole seemed a chimera even for some of those involved in the project. But AMANDA had proven that if such a detector were built, it would allow great science to come.

    The goal was simple in words but seemingly impossible in practice: 86 boreholes, each 60 cm in diameter and 2,500 m deep, had to be drilled and instrumented in seven austral summer seasons. Safety was a must, fuel needed to be used cautiously and the South Pole environment was just unavoidable.

    And yet, IceCube was completed in the seventh construction season. By that time, at the end of 2010, the IceCube drilling team had beaten all records: less time and fuel per borehole, optimized hole shapes with almost perfect vertical alignment over the 2.5-km depth, and only a few safety-related issues. How was this possible? Blame the talent, expertise and strong will of a great team.

    c
    Some of the crew at the South Pole during the last drill season for IceCube. From left to right, Hanna Blomstrom, an anonymous IceCube collaborator, Matt Newcomb, Dennis Dulling, Terry Benson, Richard Wipperfurth, Jim Haugen and Sven Lindstrom. Image: Jim Haugen. IceCube/NSF.

    Four years after IceCube’s completion and with new projects and drilling seasons on the horizon, the team that led this feat has explained the details of IceCube drilling in two papers published today in the journal Annals of Glaciology.

    “Although there was a lot of experience from AMANDA drilling, drilling for IceCube was a whole new ballgame. We continued learning lessons about the equipment and our techniques to the bitter end, but by the final seasons the drill and its crew were a well-oiled machine,” explains Terry Benson, a drill engineer at the Physical Sciences Laboratory (PSL), who started working on the IceCube drill as a young student and was one of the drill leaders during the last two construction seasons.

    “It would have been impossible to build IceCube without PSL. With them, we overcame every challenge and the results were impressive,” says Prof. Albrecht Karle, the IceCube associate director for Science and Instrumentation.

    Drilling to depths that almost reach the Antarctic bedrock also meant a larger diameter for the holes, since water starts to freeze immediately. And working at the South Pole meant that logistics and resources had to be extremely well planned and economized.

    “It was important to conserve the expensive fuel so we wanted to avoid overdrilling the holes. However, if a hole was made slightly too small, so that a string got stuck, both the hole and the string of instrumentation could be be lost. This would have been a very expensive mistake. It was extremely important to have a good understanding of hole size and freeze back rate,” explains Lee Greenler, a mechanical engineer also at PSL, who led the team developing the heat transfer calculations that allowed the optimization of the drilling process.

    i
    Image from the last IceCube drilling season at the South Pole. On the left, the hose reel for the over 2,500 meters long hose used to drill the IceCube holes. Image: Jim Haugen. IceCube/NSF.

    The drilling process started with four weeks of preparation and a crew of about 30 people. The seasonal equipment site (SES), which provided electricity and a stable supply of hot pressurized water, and the tower operations site (TOS) had to be excavated and commissioned. The SES remained stationary throughout each drill season, while drilling towers moved from one hole to another.

    “We were drilling around-the-clock, with three 9-hours shifts and only Sundays off. In season 2009-2010, when we drilled 20 holes, we sent 88 people to the Pole, but also over 450,000 liters of fuel and almost 300 tons of cargo,” explains Jim Haugen, an instrumentation engineering manager at WIPAC, who has been leading the logistics of the IceCube polar seasons since construction began.

    Drilling an IceCube hole meant shooting hot water at 80ºC through an instrumented drill head at the end of a continuous hose of about 2,500 meters. Then, during the ream phase, the drill was raised while the hot water continued to flow, enlarging the hole and keeping non-frozen water in contact with the hole walls so that it took longer to freeze back. Once 60 IceCube sensors (DOMs) were deployed, the hole completely froze around them over the following week or so.

    An independent firn drill was used for the first 50 meters, since this first layer of lower density snow does not hold water. This improved system, designed after the first seasons proved the old firn drill to be very slow, allowed an increase from 13 to 18 or more holes drilled per season.

    l
    Image from the last IceCube drilling season at the South Pole. Two drill towers were deployed to allow continuous drilling. On the front, one of the IceTop tanks. Image: Jim Haugen. IceCube/NSF.

    To drill IceCube was not an easy job, but the results now presented in these two papers show that it is possible to do large-scale production ice drilling in the Antarctic environment in a safe, efficient and predictable way. Dynamic engineering techniques based on year-to-year lessons learned and on retention of experienced crew members were critical in turning a chimera into the successful IceCube Neutrino Observatory.

    IceCube Enhanced Hot Water Drill functional description, T. Benson, J. Cherwinka, M. Duvernois, A. Elcheikh, F. Feyzi, L. Greenler, J. Haugen, A. Karle, M. Mulligan, R. Paulos. Annals of Glaciology 55(68) (2014) 105-114. doi:10.3189/2014AoG68A032.

    Modeling hole size, lifetime and fuel consumption in hot-water ice drilling, L. Greenler, T. Benson, J. Cherwinka, A. Elcheikh, F. Feyzi, A. Karle, R. Paulos. Annals of Glaciology 55(68) (2014) 115-123. doi:10.3189/2014AoG68A033.

    See the full article here.

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 4:11 pm on December 12, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From IceCube: “More on astrophysical neutrinos yet no track of charmed mesons” 

    icecube
    IceCube South Pole Neutrino Observatory

    07 Oct 2014
    Silvia Bravo

    A search for neutrino interactions inside IceCube brought evidence of an extraterrestrial neutrino flux. Now the IceCube Collaboration has expanded the search, lowering the range of deposited energy down to 1 TeV. The goal was a better understanding of the different contributions to the neutrino flux in IceCube and hopefully to measure the charmed-meson component for the first time.

    The results of this study, submitted today to Physical Review D, have again proven neutrinos from charmed-meson decays to be elusive. The good news is the results set a more stringent upper limit on their contribution, only 1.52 times the theoretical benchmark prediction used in previous IceCube analyses. IceCube researchers have also derived new constraints on the diffuse astrophysical neutrino spectrum, .

    d
    Deposited energy spectra from the northern and southern skies (points) with the best fit combination of atmospheric and astrophysical contributions from table below. Above 10 TeV, an extra component is required to account for the observed high-energy events, especially those in the southern sky. The excess over the best fit sum around 30 TeV is interpreted as a statistical fluctuation. Image: IceCube Collaboration

    High-energy neutrinos may be produced either by the interaction of cosmic rays in the Earth’s atmosphere, the so-called atmospheric neutrinos, or in the vicinity of distant astrophysical accelerators like black holes and neutron stars, the so-called astrophysical neutrinos.

    Whether atmospheric or astrophysical, neutrinos come in different flavors, but their rates and their energy and direction distributions can help us distinguish the different contributions to the overall flux and learn more about their origins and production mechanisms.

    Atmospheric neutrinos are mainly muon neutrinos produced in 2-body decays of charged pions and kaons. The electron neutrino component is primarily due to 3-body decays of charged and neutral kaons. And there’s still a third contribution from the decays of heavy, short-lived mesons containing charm quarks, which create approximately the same amount of muon and electron neutrinos. However, this third prompt contribution has never been conclusively observed.

    Astrophysical neutrinos, which may have been created by diffusive shock acceleration in the vicinity of cosmic ray sources, will arrive to Earth with an equal ratio for the three flavors (muon, electron and tau neutrinos) and with an energy spectrum expected to follow that of the progenitor protons (e ). Thus, their flux will exceed that of atmospheric neutrinos at very high energies.

    The current search was looking for neutrino-induced interactions starting in the IceCube detector with energies between 1 TeV and beyond a few PeV, exploring for the first time the region between 10 and 100 TeV, where neutrinos from charmed-meson decays in the atmosphere should be observable. There were 388 events found in IceCube data from 2010-2012, which should include contributions from conventional and prompt atmospheric neutrinos, and extraterrestrial neutrinos, along with a small but nearly irreducible background of penetrating atmospheric muons that go undetected before depositing a large fraction of their energy in the glacial ice in a single, catastrophic loss.

    t
    Table: Results for the best fit parameters and number of events attributable to each neutrino component.

    The best fit of each of these contributions to the observed neutrino flux in IceCube shows a good agreement with previous results, except in the region around 30 TeV in the southern sky (see figure and table above) where an extra component might be required to account for the observed events.

    “Isolating neutrino interactions is more difficult at these lower energies, but we are seeing interesting things. Some, like the observation of the atmospheric neutrino flux at the observed level, were expected and are a nice confirmation of our understanding of the IceCube detector,” explains Jakob van Santen, a graduate student at WIPAC at the University of Wisconsin–Madison. “Others, like the excess over our simple model of the astrophysical neutrino flux in the southern sky around 30 TeV, a region where we expect our vetoes to remove nearly all atmospheric muons and neutrinos, were a surprise. While the deviation isn’t statistically significant, this may be a hint that our simplest model for the astrophysical neutrino flux is incomplete. To find out more, we’ll need more data.”

    The spectral index for astrophysical neutrinos is larger than 2.2, which may be a hint for a galactic neutrino component of this flux. At higher energies, though, neutrinos from extragalactic sources would be the dominant ones. However, the best fit to this index hardens to 2.25 if the energy threshold is raised to 60 TeV, again an indication that we need more data to understand the neutrino flux with energies around 30 TeV in IceCube.

    Atmospheric and Astrophysical Neutrinos above 1 TeV Interacting in IceCube, IceCube Collaboration: M.G. Aartsen et al. Submitted to Physical Review D, arXiv.org:1410.1749

    See the full article here.

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 1:29 pm on December 11, 2014 Permalink | Reply
    Tags: , INFN Gran Sasso, Neutrinos,   

    From Symmetry: “ICARUS hits the road” 

    Symmetry

    December 11, 2014
    Kathryn Jepsen

    A giant neutrino detector is traveling by truck from the Italian Gran Sasso laboratories to CERN to get ready for a new life.

    On Tuesday night a 600-metric-tonne particle detector became the world’s largest neutrino experiment currently on an international road trip.

    The ICARUS T600 neutrino detector—the world’s largest liquid-argon neutrino experiment—is on its way from the INFN Gran Sasso laboratories in Italy to European research center CERN on the border of France and Switzerland. Once it arrives at CERN, it will undergo upgrades to prepare it for a second life.

    INFN Gran Sasso ICARUS
    INFN Gran Sasso ICARUS T600
    INFN Gran Sasso ICARUS T600

    “ICARUS is presently the state-of-the-art technology,” says Nobel Laureate Carlo Rubbia, the leader of the ICARUS experiment. “Its success has demonstrated the enormous potentials of this detector technique… Most of the ICARUS developments have become part of the liquid-argon technology that is now being used is most of the other, more recent projects.”

    Since 2010, the ICARUS experiment has studied neutrinos streaming about 450 miles straight through the Earth from CERN to Gran Sasso. Neutrinos come in three types, called flavors, and they switch flavors as they travel. The ICARUS experiment was set up to study those flavor oscillations. Its detector, which works like a huge, three-dimensional camera that visualizes subatomic events, has recorded several thousand neutrino interactions.

    Scientists see more experiments in the detector’s future, possibly using a powerful beam of neutrinos already in operation at Fermi National Accelerator Laboratory near Chicago.

    The detector is 6 meters wide, 18 meters long and 4 meters high. When in operation, it is filled with ultra-pure liquid argon and about 52,000 wires, which collect signals from particles and can reconstruct 3-D images of a what happens when a neutrino knocks an electron off of an atom of argon.

    To prepare the sensitive detector for transport, workers moved its inner chamber on sleds into a shipping container, says Chiara Zarra, the ICARUS movement and transportation coordinator. But getting the experiment out of its home was a challenge, she says. The laboratory layout had changed since ICARUS was first installed, and there were multiple other experiments to maneuver through. A team from CERN helped with planning by creating 3-D simulations of the operation.

    t
    Over the course of about a week, the detector will travel on a special equipment transporter through Rome, Genoa and Turin. After that it will cross the Alps through the Mont Blanc tunnel on its way to Geneva.
    Courtesy of: INFN

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:53 am on December 11, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “How to make a neutrino beam” 


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

    Thursday, Dec. 11, 2014
    Tia Miceli

    line
    Ingredients for a neutrino beam: speedy protons, target, magnetic horn, decay pipe, absorbers. Image adapted from Fermilab

    Fermilab is in the middle of expanding its neutrino program and is developing new detectors to study these ghostly particles. With its exquisite particle accelerator complex, Fermilab is capable of creating very intense beams of neutrinos.

    Our neutrino recipe starts with a tank of hydrogen. The hydrogen atoms are fed an extra electron to make them negatively charged, allowing them to be accelerated. Once the charged atoms are accelerated, all of the electrons are ripped off, leaving a beam of positive protons. The protons are extracted into either the Booster Neutrino Beamline (BNB) or are further accelerated and extracted into the Neutrino Main Injector beamline (NuMI). Fermilab is the only laboratory with two neutrino beams. Our two beams have different energies, which allows us to study different properties of the neutrinos.

    FNAL Booster Neutrino
    Booster Neutrino Beamline

    FNAL NuMI upgrade
    NuMI upgrade

    In the BNB, these protons smash into a target to break up the strong bonds of the quarks inside the proton. These collisions are so violent that they produce new quarks from their excess energy. These quarks immediately form together again into lighter composite short-lived particles called pions and kaons.

    Since the pions and kaons emerge at different directions and speeds, they need to be herded together. As a bugle tunes your breath into musical notes, a horn of a different type rounds up and focuses the pions and kaons. The BNB horn looks roughly like the bell of a six-foot long bugle. It produces an electric field that in turn generates a funnel-like magnetic field, which directs all of the dispersed pions and kaons of positive electric charge straight ahead. Particles with negative charges get defocused. By switching the direction of the electric field, we can focus the negatively charged particles while defocusing the positive charges.

    The focused particles in the BNB beam travel through a 50-meter long tunnel. This is where the magic happens. In this empty tunnel, the pions and kaons decay in flight into neutrinos, electrons and muons. At the end of the decay tunnel is a wall of steel and concrete to stop and absorb any particle that is not a neutrino. Because neutrinos interact so rarely, they easily whiz through the absorbers and on towards the experiments. And that’s the basic formula to make a beam of neutrinos!

    A single neutrino beamline can support many experiments because the neutrinos interact too rarely to get “used up.” The BNB feeds neutrinos to MicroBooNE, and most of them go on through to the other side towards the MiniBooNE detector. Similarly, most of those go on through the other side as well and continue traveling to infinity and beyond. Detectors located in this beam measure neutrino oscillations and their interactions.

    FNAL MiniBoone
    MiniBooNE

    The NuMI beamline is designed similarly, but uses a different target material, two focusing horns, and a 675-meter decay pipe. The spacing between the two NuMI horns is adjustable, allowing fine-tuning of the neutrino beam energy. The NuMI beamline has higher-energy neutrinos than the BNB and thus studies different properties of neutrino oscillations.

    The NuMI beamline feeds neutrinos to the MINERvA experiment and on through to the MINOS near detector. The NuMI beamline then continues about 450 miles through Earth on toward the MINOS far detector in the Soudan mine in Minnesota. By the time the beam reaches the far detector, it is about 20 miles in diameter! By having a near and far detector, we are able to observe neutrino flavor oscillations by measuring how much of the beam is electron neutrino flavor and muon neutrino flavor at each of these two detectors.

    FNAL Minerva
    MINERvA

    The last of the big Fermilab neutrino experiments is NOvA. Its near detector is off to the side of the NuMI beam and measures neutrinos only with a specific range of direction and energy. The NOvA far detector is positioned to measure the neutrinos with the same properties at a greater distance, about 500 miles away in Ash River, Minnesota. By placing the NOvA detectors 3 degrees to the side of the beam’s center, NOvA will get to make more precise oscillation measurements for a range of neutrino energies.

    FNAL NOvA experiment
    NOvA and MINOS far detectors

    As more experiments are designed with more demanding requirements, Fermilab may expect to see more neutrino beamline R&D and the construction of new beamlines.

    See the full article here.

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  • richardmitnick 12:46 pm on December 9, 2014 Permalink | Reply
    Tags: , , FNAL LBNF, Neutrinos   

    From FNAL- “Director’s Corner: Toward a strong, international neutrino collaboration” 


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

    Tuesday, Dec. 9, 2014
    nl
    Fermilab Director Nigel Lockyer

    Fermilab has always been an international laboratory. With the proposed Long-Baseline Neutrino Facility based here at Fermilab, we’re about to enter a bold new era of global cooperation.

    This Friday, Dec. 12, Fermilab will host the second of two open meetings about LBNF. These meetings are a big step toward forming a strong collaboration with partners across the globe, with the goal of building the best neutrino experiment of its kind in the world.

    Last Friday, the first of these meetings took place at CERN. We introduced CERN’s Director of Research Sergio Bertolucci as the interim chair of the International Institutional Board of the new collaboration, and we explained the organizational structure that we plan to put in place, with input and participation from international funding agencies. Rob Roser walked us through the current draft of the letter of intent for the experiment. Meeting participants discussed how to optimize the design of the experiment and started to discuss the scientific strategy. Many aspects of the experiment are still under discussion, and we are actively seeking input from all interested scientists. The goal is to finalize the letter of intent by Dec. 21 and submit it for review by the Fermilab Physics Advisory Committee, which will meet in January.

    This Friday it’s our turn to host the second meeting, which has an agenda identical to the first one. It will be held in One West from 10 a.m. to 3 p.m. All interested scientists, from graduate students to engineers to principal investigators, are encouraged to attend. Please register for the meeting so that we know approximately how many people to expect.

    The meeting will be a chance to voice your questions and ideas. There will be a panel discussion with an extended Q&A. An agenda with call-in information can be found online.

    The next major event in forming a new collaboration for long-baseline neutrino physics will be the PAC meeting on Jan. 15 and 16 at Fermilab. Sergio Bertolucci will present the letter of intent to the PAC on behalf of the nascent collaboration.

    See the full article here.

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  • richardmitnick 11:51 pm on November 27, 2014 Permalink | Reply
    Tags: , , , , GNN, Neutrinos   

    From CERN Courier: “The Global Neutrino Network takes off” 

    CERN Courier

    Nov 27, 2014
    GNN Global Neutrino Network

    On 20–12 September, CERN hosted the fifth annual Mediterranean-Antarctic Neutrino Telescope Symposium (MANTS) . For the first time, the meeting was organized under the GNN umbrella.

    The idea to link more closely the various neutrino telescope projects under both water and ice has been a topic for discussion in the international community of high-energy neutrino astrophysicists for several years. On 15 October 2013, representatives of the ANTARES, BAIKAL, IceCube and KM3NeT collaborations signed a memorandum of understanding for co-operation within a Global Neutrino Network (GNN). GNN aims for extended inter-collaboration exchanges, more coherent strategy planning and exploitation of the resulting synergistic effects.

    No doubt, the evidence for extraterrestrial neutrinos recently reported by IceCube at the South Pole (“Cosmic neutrinos and more: IceCube’s first three years”) has given wings to GNN, and is encouraging the KM3NeT (in the Mediterranean Sea) and GVD (Lake Baikal) collaborations in their efforts to achieve appropriate funding to build northern-hemisphere cubic-kilometre detectors. IceCube is also working towards an extension of its present configuration.

    One focus of the MANTS meeting was, naturally, on the most recent results from IceCube and ANTARES, and their relevance for future projects. The initial configurations of KM3NeT (with three to four times the sensitivity of ANTARES) and GVD (with sensitivity similar to ANTARES) could provide additional information on the characteristics of the IceCube signals, first because they look at a complementary part of the sky, and second because water has optical properties that are different from ice. Cross-checks with different systematics are of the highest importance for these detectors in natural media. As an example, KM3NeT will measure down-going muons from cosmic-ray interactions in the atmosphere with superb precision. This could help in determining more precisely the flux of atmospheric neutrinos co-generated with those muons, in particular those from the decay of charmed mesons, which are expected to have particularly high energies and therefore could mimic an extraterrestrial signal.

    A large part of the meeting was devoted to finding the best “figures of merit” characterizing the physics capabilities of the detectors. These not only allow comparison of the different projects, but also provide an important tool to optimize future detector configurations. The latter also concerns the two sub-projects that aim to determine the neutrino mass hierarchy using atmospheric neutrinos. These are both small, high-density versions of the huge kilometre-scale arrays: PINGU at the South Pole and ORCA in the Mediterranean Sea. In this effort a particularly close co-operation has emerged during the past year, down to technical details.

    Combining data from different detectors is another aspect of GNN. A recent common analysis of IceCube and ANTARES sky maps has provided the best sensitivity ever for point sources in certain regions of the sky, and will be published soon. Further goals of GNN include the co-ordination of alert and multimessenger policies, exchange and mutual checks of software, creation of a common software pool, development of standards for data representation, cross-checks of results with different systematics, and the organization of schools and other forums for exchanging expertise and experts. Mutual representation in the experiments’ science advisory committees is another way to promote close contact and mutual understanding.

    Contingent upon availability of funding, the mid 2020s could see one Global Neutrino Observatory, with instrumented volumes of 5–8 km3 in each hemisphere. This would, finally, fully raise the curtain just lifted by IceCube, and provide a rich view on the high-energy neutrino sky.

    See the full article here.

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  • richardmitnick 2:46 pm on November 26, 2014 Permalink | Reply
    Tags: , , , Neutrinos, Scintillators   

    From FNAL: “Scintillator extruded at Fermilab detects particles around the globe” 


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

    Wednesday, Nov. 26, 2014
    Troy Rummler

    Small, clear pellets of polystyrene can do a lot. They can help measure cosmic muons at the Pierre Auger Observatory, search for CP violation at KEK in Japan or observe neutrino oscillation at Fermilab. But in order to do any of these they have to go through Lab 5, located in the Fermilab Village, where the Scintillation Detector Development Group, in collaboration with the Northern Illinois Center for Accelerator and Detector Design (NICADD), manufactures the exclusive source of extruded plastic scintillator.

    scin
    The plastic scintillator extrusion line, shown here, produces detector material for export to experiments around the world. Photo: Reidar Hahn

    Like vinyl siding on a house, long thin blocks of plastic scintillator cover the surfaces of certain particle detectors. The plastic absorbs energy from collisions and releases it as measurable flashes of light. Fermilab’s Alan Bross and Anna Pla-Dalmau first partnered with local vendors to develop the concept and produce cost-effective scintillator material for the MINOS neutrino oscillation experiment. Later, with NIU’s Gerald Blazey, they built the in-house facility that has now exported high-quality extruded scintillator to experiments worldwide.

    “It was clear that extruded scintillator would have a big impact on large neutrino detectors,” Bross said, “but its widespread application was not foreseen.”

    Industrially manufactured polystyrene scintillators can be costly — requiring a labor-intensive process of casting purified materials individually in molds that have to be cleaned constantly. Producing the number of pieces needed for large-scale projects such as MINOS through casting would have been prohibitively expensive.

    Extrusion, in contrast, presses melted plastic pellets through a die to create a continuous noodle of scintillator (typically about four centimeters wide by two centimeters tall) at a much lower cost. The first step in the production line mixes into the melted plastic two additives that enhance polystyrene’s natural scintillating property. As the material reaches the die, it receives a white, highly reflective coating that holds in scintillation light. Two cold water tanks respectively bathe and shower the scintillator strip before it is cool enough to handle. A puller controls its speed, and a robotic saw finally cuts it to length. The final product contains either a groove or a hole meant for a wavelength-shifting fiber that captures the scintillation light and sends the signal to electronics in the most useful form possible.

    Bross had been working on various aspects of the scintillator cost problem since 1989, and he and Pla-Dalmau successfully extruded experiment-quality plastic scintillator with their vendors just in time to make MINOS a reality. In 2003, NICADD purchased and located at Lab 5 many of the machines needed to form an in-house production line.

    “The investment made by Blazey and NICADD opened extruded scintillators to numerous experiments,” Pla-Dalmau said. “Without this contribution from NIU, who knows if this equipment would have ever been available to Fermilab and the rest of the physics community?”

    Blazey agreed that collaboration was an important part of the plastic scintillator development.

    “Together the two institutions had the capacity to build the resources necessary to develop state-of-the-art scintillator detector elements for numerous experiments inside and outside high-energy physics,” Blazey said. “The two institutions remain strong collaborators.”

    Between their other responsibilities at Fermilab, the SDD group continues to study ways to make their scintillator more efficient. One task ahead, according to Bross, is to work modern, glass wavelength-shifting fibers into their final product.

    “Incorporation of the fibers into the extrusions has always been a tedious part of the process,” he said. “We would like to change that.”

    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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