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  • richardmitnick 2:09 pm on August 31, 2018 Permalink | Reply
    Tags: , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “Understanding inelasticity in high-energy neutrino interactions with IceCube” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    From From U Wisconsin IceCube Collaboration

    31 Aug 2018
    Sílvia Bravo


    Once or twice per day, a muon neutrino interacts with a molecule of ice near one of the 5,000 sensors of the IceCube Neutrino Observatory. This weak interaction mediated by W boson is what scientists call a charged-current interaction, which produces a hadronic shower and a muon. The muon travels across the detector in a straight line, following almost the same direction as the original neutrino.

    This hadronic shower carries a fraction of the energy of the original neutrino, a parameter known as inelasticity. A better understanding of the inelasticity of neutrino interactions provides another way of deepening our knowledge of the unique physics hiding behind ghostly neutrinos.

    The IceCube Collaboration has recently presented its first measurements of the neutrino inelasticity, which are also the first-ever at very high energies—from 1 TeV up to nearly 800 TeV. The inelasticity distribution was found to be in good agreement with Standard Model prediction and was later used to perform other measurements, such as charm production in neutrino interactions or flavor composition of astrophysical neutrinos.

    These measurements are summarized in a paper recently submitted to Physical Review D and, together with previous measurements of the neutrino cross-section, show the potential of astrophysical and atmospheric neutrinos as a tool for particle and nuclear physics at high energies.

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    The mean inelasticity obtained from the fit in five bins of reconstructed energy. Vertical error bars indicate the 68% confidence interval for the mean inelasticity, and horizontal error bars indicate the expected central 68% of neutrino energies in each bin. The predicted mean inelasticity is shown in blue for neutrinos and in green for antineutrinos. A flux-averaged mean inelasticity is shown in red. Credit: IceCube Collaboration

    Scientists analyzed five years of IceCube data looking for starting multi-TeV neutrino interactions and found 2,650 tracks and 965 cascades. These tracks are mostly charged-current muon neutrino interactions for which the energy and inelasticity were measured.

    “The measurement of inelasticity was made possible with concepts from machine learning. Using thousands of simulated neutrino interactions, we were able to train a computer algorithm to learn the energy of the hadronic shower and the muon from the complicated pattern of light detected by IceCube’s sensors,” explains Gary Binder, who worked in this analysis during his PhD at the University of California, Berkeley.

    Neutrino inelasticity depends on the momentum distribution of quarks and antiquarks within nuclei. For example, the production of charm quarks is sensitive to the number of strange sea quarks in the nucleus. And a fit to IceCube data revealed charm quark production with more than 90% confidence.

    On the other hand, the inelasticity distributions for neutrinos and antineutrinos are somewhat different, and IceCube data allows to measure the ratio of antineutrinos to neutrinos produced in cosmic-ray air showers.

    “This analysis shows that IceCube can make significant contributions to the study of neutrino interactions, probing energies that are far beyond those accessible with terrestrial accelerators,” explains Spencer Klein, an IceCube researcher at Lawrence Berkeley National Laboratory and at University of California, Berkeley, and a coauthor of this work.

    This first measurement of the neutrino inelasticity at high energies also proved to be useful for studies of the astrophysical neutrino flux. The inclusion of inelasticity in an otherwise standard IceCube fit provides tighter constraints on the flavor composition of astrophysical neutrinos.

    This study developed a new approach to reconstructing starting tracks. It measured, separately, the energy of the cascade produced by the neutrino interaction and the muon that emerged from it. The sum gives the total energy, and the ratio of the cascade energy to the total energy is the inelasticity. The new technique produces a far more accurate energy estimate for starting tracks, which can be used to better probe the astrophysical neutrino energy spectrum¬¬––the current study found that starting tracks are consistent with other IceCube measurements.

    These results confirm that large-scale neutrino detectors can measure the inelasticity distribution of high-energy neutrinos, but the cubic-kilometer Antarctic detector has not yet reached the sensitivity that will enable precision tests of the neutrino sector and thus rigorous searches for new physics. Looking ahead, the inclusion of inelasticity in future IceCube starting event analyses will further tighten the constraints on the presence of tau neutrinos. More generally, inelasticity measurements are now known to be a robust tool for future, larger neutrino telescopes, such as the ten-cubic kilometer IceCube-Gen2 or the Mediterranean neutrino detector KM3NeT.

    3
    Artistic expression of KMNeT http://www.km3net.org

    5
    KM3NeT Digital Optical Module (DOM) in the laboratory. http://www.km3net.org

    See the full article here .

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    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 5:03 am on August 15, 2018 Permalink | Reply
    Tags: , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Nature via U Wisconsin IceCube: “Special relativity validated by neutrinos” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    Nature Mag
    From Nature

    13 August 2018
    Matthew Mewes

    Neutrinos are tiny, ghost-like particles that habitually change identity. A measurement of the rate of change in high-energy neutrinos racing through Earth provides a record-breaking test of Einstein’s special theory of relativity.

    The existence of extremely light, electrically neutral particles called neutrinos was first postulated in 1930 to explain an apparent violation of energy conservation in the decays of certain unstable atomic nuclei. Writing in Nature Physics, the IceCube Collaboration1 now uses neutrinos seen in the world’s largest particle detector to scrutinize another cornerstone of physics: Lorentz invariance. This principle states that the laws of physics are independent of the speed and orientation of the experimenter’s frame of reference, and serves as the mathematical foundation for Albert Einstein’s special theory of relativity. Scouring their data for signs of broken Lorentz invariance, the authors carry out one of the most stringent tests of special relativity so far, and demonstrate how the peculiarities of neutrinos can be used to probe the foundations of modern physics.

    Physicists generally assume that Lorentz invariance holds exactly. However, in the late 1990s, the principle began to be systematically challenged2, largely because of the possibility that it was broken slightly in proposed theories of fundamental physics, such as string theory3. Over the past two decades, researchers have tested Lorentz invariance in objects ranging from photons to the Moon4.

    The IceCube Collaboration instead tested the principle using neutrinos. Neutrinos interact with matter through the weak force — one of the four fundamental forces of nature. The influence of the weak force is limited to minute distances. As a result, interactions between neutrinos and matter are extremely improbable, and a neutrino can easily traverse the entire Earth unimpeded. This poses a challenge for physicists trying to study these elusive particles, because almost every neutrino will simply pass through any detector completely unnoticed.

    The IceCube Neutrino Observatory, located at the South Pole, remedies this problem by monitoring an immense target volume to glimpse the exceedingly rare interactions. At the heart of the detector are more than 5,000 light sensors, which are focused on 1 cubic kilometre (1 billion tonnes) of ice. The sensors constantly look for the telltale flashes of light that are produced when a neutrino collides with a particle in the ice.

    The main goal of the IceCube Neutrino Observatory is to observe comparatively scarce neutrinos that are produced during some of the Universe’s most violent astrophysical events. However, in its test of Lorentz invariance, the collaboration studied more-abundant neutrinos that are generated when fast-moving charged particles from space collide with atoms in Earth’s atmosphere. There are three known types of neutrino: electron, muon and tau. Most of the neutrinos produced in the atmosphere are muon neutrinos.

    Atmospheric neutrinos generated around the globe travel freely to the South Pole, but can change type along the way. Such changes stem from the fact that electron, muon and tau neutrinos are not particles in the usual sense. They are actually quantum combinations of three ‘real’ particles — ν1, ν2 and ν3 — that have tiny but different masses.

    In a simple approximation relevant to the IceCube experiment, the birth of a muon neutrino in the atmosphere can be thought of as the simultaneous production of two quantum-mechanical waves: one for ν2 and one for ν3 (Fig. 1). These waves are observed as a muon neutrino only because they are in phase, which means the peaks of the two waves are seen at the same time. By contrast, a tau neutrino results from out-of-phase waves, whereby the peak of one wave arrives with the valley of the other.

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    Figure 1 | Propagation of neutrinos through Earth. There are three known types of neutrino: electron, muon and tau. a, A muon neutrino produced in Earth’s atmosphere can be thought of as the combination of two quantum-mechanical waves (red and blue) that are in phase — the peaks of the waves are observed at the same time. If a principle known as Lorentz invariance were violated, these waves could travel at different speeds through Earth’s interior and be detected in the out-of-phase tau-neutrino state. b, The IceCube Collaboration1 reports no evidence of such conversion, constraining the extent to which Lorentz invariance could be violated.

    If neutrinos were massless and Lorentz invariance held exactly, the two waves would simply travel in unison, always maintaining the in-phase muon-neutrino state. However, small differences in the masses of ν2 and ν3 or broken Lorentz invariance could cause the waves to travel at slightly different speeds, leading to a gradual shift from the muon-neutrino state to the out-of-phase tau-neutrino state. Such transitions are known as neutrino oscillations and enable the IceCube detector to pick out potential violations of Lorentz invariance. Oscillations resulting from mass differences are expected to be negligible at the neutrino energies considered in the authors’ analysis, so the observation of an oscillation would signal a possible breakdown of special relativity.

    The IceCube Collaboration is not the first group to seek Lorentz-invariance violation in neutrino oscillations [5–10]. However, two key factors allowed the authors to carry out the most precise search so far. First, atmospheric neutrinos that are produced on the opposite side of Earth to the detector travel a large distance (almost 13,000 km) before being observed, maximizing the probability that a potential oscillation will occur. Second, the large size of the detector allows neutrinos to be observed that have much higher energies than those that can be seen in other experiments.

    Such high energies imply that the quantum-mechanical waves have tiny wavelengths, down to less than one-billionth of the width of an atom. The IceCube Collaboration saw no sign of oscillations, and therefore inferred that the peaks of the waves associated with ν2 and ν3 are shifted by no more than this distance after travelling the diameter of Earth. Consequently, the speeds of the waves differ by no more than a few parts per 10^28 — a result that is one of the most precise speed comparisons in history.

    The authors’ analysis provides support for special relativity and places tight constraints on a number of different classes of Lorentz-invariance violation, many for the first time. Although already impressive, the IceCube experiment has yet to reach its full potential. Because of limited data, the authors restricted their attention to violations that are independent of the direction of neutrino propagation, neglecting possible direction-dependent violations that could arise more generally.

    With a greater number of neutrino detections, the experiment, or a larger future version [11], could search for direction-dependent violations. Eventually, similar studies involving more-energetic astrophysical neutrinos propagating over astronomical distances could test the foundations of physics at unprecedented levels.

    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.

    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 5:42 pm on July 16, 2018 Permalink | Reply
    Tags: , Lorentz symmetry, , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube: “IceCube neutrinos pass a test of a fundamental symmetry in nature” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    From From U Wisconsin IceCube

    6 Jul 2018
    Sílvia Bravo

    Science relies on the premise that nature’s laws are the same for anyone running an experiment. This may seem obvious to someone sitting on a couch at home, but for many of the objects we study—huge or tiny—that are fleeting through space and matter, it might not be the case.

    Scientists call this property Lorentz symmetry—that the laws of physics stay the same as long as observers move at constant speed, no matter the direction, with respect to each other—and many theories, including general relativity, rely on it. A well-known consequence of this symmetry is that the speed of light remains constant at 300 million meters per second.

    Several models trying to unify under one single theory both quantum theory and gravitation predict Lorentz violation at extremely, but significant, small scales. And, as one might guess, bizarre neutrinos could be the particles to reveal which theory is correct. However, for now, we don’t have an answer. A new measurement of the IceCube Collaboration has put Lorentz symmetry to the test and found—yet again—that neutrinos behave as expected. The results, published in Nature Physics, are the most stringent limits to date in the neutrino sector on the existence of a Lorentz violating field.

    1
    Muon neutrinos produced in the upper atmosphere are detected by IceCube in Antarctica. The potential signal is the anomalous disappearance of muon neutrinos, which might be caused by the presence of a hypothetical LV field that permeates space. The effect can be directional (arrows), but in this analysis we test the isotropic component. Credit: IceCube Collaboration.

    Since they were first postulated, neutrinos have been considered as tantalizing signatures of yet to be discovered new physics. The observation of neutrino oscillations––probably the most studied quantum phenomena––answered positively to whether these ghostly particles had mass while at the same time generating more puzzles to be solved.

    In a universe where the Lorentz symmetry can be breached, such as a universe where gravity can also be explained with quantum theories, the morphing of neutrinos from one type, or flavor, to another would deviate from standard neutrino oscillations. The effects of the interaction of neutrinos with a Lorentz violating field, or the aftermath of a small distortion of space-time, would be enhanced by the quantum interference of the different flavors and result in significant changes on the oscillation pattern.

    “Neutrino oscillations are a natural interferometer,” explains Teppei Katori, an assistant professor at Queen Mary University of London and one of the main analyzers of this work. And IceCube neutrinos are the ones with the highest energies ever the detected, produced by cosmic-ray protons colliding with atoms in the Earth’s atmosphere or coming directly from distant and powerful cosmic accelerators. “Neutrino oscillations observed with IceCube act as the biggest interferometer in the world to look for the tiniest effects in physics, such as a space-time deficit,” adds Katori.

    It was a legendary interferometer, the so-called Michelson and Morley experiment, that using a beam of light proved that space was not full of ether. A better theory to understand the nature of space was proposed by Einstein, and since then we understand space and time to be in a four-dimensional continuum.

    “We would love to be the direct descendants of Michelson and Morley, using interferometry to show that a beautiful field theory, in this case Einstein’s theory, is right, but not sufficient—that there is new physics out there that underlies our present model,” says Janet Conrad, a professor at MIT who also participated in this study.

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    The parameter ρ6 represents the Lorentz Violating field strength. The best-fit point is shown by the yellow cross and the blue (red) region is excluded at 99% (90%) C.L. Credit: IceCube Collaboration.

    IceCube researchers have looked for effects of an isotropic Lorentz violating field using two years of throughgoing atmospheric neutrinos with energies around and above one TeV. The results have not found variations in the typical neutrino oscillation patterns that could be pointing to new physics. “We have looked for missing muon neutrinos on the highest energy atmospheric events observed by IceCube and have found no significant deficit,” says Carlos Argüelles, a postdoctoral researcher at MIT and also a main analyzer of this work. “We’re getting closer to the Planck scale: an unexplored terrain where general relativity and quantum mechanics are both important. Exciting times lie ahead as we continue looking for strange flavor changes at higher and higher energies.”

    This nonobservation allowed setting the strongest limits to date on Lorentz violating fields in the neutrino sector. When looking at results from other types of experiments, these limits are also among the best in the world, showing the potential of neutrino experiments to study fundamental space-time properties.

    “IceCube’s access to the high-energy regime, along with its high statistics, makes it a powerful instrument to study physics beyond the standard model. This enabled us to probe for small distortions induced by Lorentz invariance violation in the atmospheric neutrino flux that are not accessible to other detectors,” says Ali Kheirandish, a postdoctoral researcher at UW–Madison and also an analyzer of this work.

    Improvements to these measurements are already in the works. The addition of astrophysical neutrinos will increase sensitivity to higher energies, where many searches for new physics could reach the precision to prove or rule out some theories.

    The IceCube analysis focused on an isotropic Lorentz violating field since its impact on neutrino oscillation signatures may be expected to be up to 1,000 larger than the impact from a directional field. However, as sensitivity increases, IceCube will also test directional fields, which are considered a smoking gun signature of Lorentz violation. Future extensions of IceCube as well as water-based neutrino detectors will provide larger samples of astrophysical neutrinos and will boost tests of the most fundamental symmetries in nature.

    See the full article here .

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    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 2:40 pm on July 15, 2018 Permalink | Reply
    Tags: , , , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Spaceflight Insider: “Fermi Telescope discovers neutrino’s origin as supermassive black hole” 

    1

    From Spaceflight Insider

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    A cosmic neutrino detected by NASA’s Fermi Gamma-ray Space Telescope was found to have originated in a gamma ray emitted by a supermassive black hole 3.7 billion light years away at the center of a galaxy in the constellation Orion.

    The discovery, made by an international team of scientists, marks the first time a high-energy neutrino from beyond the Milky Way has been traced to its place of origin as well as the furthest any neutrino has been known to travel.

    Neutrinos are high-energy, hard-to-catch particles likely produced in powerful cosmic events, such as supermassive black holes actively devouring matter and galaxy mergers. Because they travel at nearly the speed of light and do not interact with other matter, they are capable of traversing billions of light years.

    By studying neutrinos, scientists gain insight into the processes that drive powerful cosmic events, including supernovae and black holes.

    Gamma rays are the brightest and most energetic form of light, which is why scientists use them to trace the sources of neutrinos and cosmic rays.

    “The most extreme cosmic explosions produce gravitational waves, and the most extreme cosmic accelerators produce high-energy neutrinos and cosmic rays,” explained Regina Caputo of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and analysis coordinator for the Fermi Large Area Telescope Collaboration. “Through Fermi, gamma rays are providing a bridge to each of these new cosmic signals.”

    Scientists found this particular neutrino on September 22, 2017, using the National Science Foundation‘s (NSF) IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station. They then traced the neutrino to its origin in a gamma ray blast within the distant supermassive black hole using Fermi.[ https://sciencesprings.wordpress.com/2018/07/13/the-great-neutrino-catch-a-bunch-of-articles/ ]

    “Again, Fermi has helped make another giant leap in a growing field we call multimessenger astronomy. Neutrinos and gravitational waves deliver new kinds of information about the most extreme environments in the universe. But to understand what they’re telling us, we need to connect them to the ‘messenger’ astronomers know best–light,” emphasized Paul Hertz, director of NASA’s Astrophysics Division in Washington, DC.

    IceCube tracked the neutrino, which hit Antarctica with 300 trillion electron volts. Its extremely high energy level meant it likely came from beyond our solar system. Its galaxy of origin, with which scientists are familiar, is a blazar, a galaxy with an extremely bright and active central supermassive black hole that blasts out jets of particles in opposite directions at nearly the speed of light.

    Blazars have several million to several billion times the mass of our Sun. Scientists find them when one of the jets they emit travels in the direction of Earth.

    Yasuyuki Tanaka of Japan’s Hiroshima University was the first scientist to link the neutrino to a specific blazar known as TXS 0506+056, which has recently shown increased activity. Fermi keeps track of approximately 2,000 blazars.

    Followup observations of TXS 0506 were conducted with the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) NASA’s Neil Gehrels Swift Observatory, and various other observatories.[See above link to previous post Bunch of Articles]

    Two papers on the discovery have been published here and here in the journal Science.

    See the full article here .

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    SpaceFlight Insider reports on events taking place within the aerospace industry. With our team of writers and photographers, we provide an “insider’s” view of all aspects of space exploration efforts. We go so far as to take their questions directly to those officials within NASA and other space-related organizations. At SpaceFlight Insider, the “insider” is not anyone on our team, but our readers.

    Our team has decades of experience covering the space program and we are focused on providing you with the absolute latest on all things space. SpaceFlight Insider is comprised of individuals located in the United States, Europe, South America and Canada. Most of them are volunteers, hard-working space enthusiasts who freely give their time to share the thrill of space exploration with the world.

     
  • richardmitnick 3:07 pm on July 12, 2018 Permalink | Reply
    Tags: Blazar, , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From NRAO via newswise: “VLA Gives Tantalizing Clues About Source of Energetic Cosmic Neutrino” 

    NRAO Icon
    From National Radio Astronomy Observatory

    NRAO Banner

    via

    2

    newswise

    1
    Supermassive black hole at core of galaxy accelerates particles in jets moving outward at nearly the speed of light. In a Blazar, one of these jets is pointed nearly straight at Earth. Credit: Sophia Dagnello, NRAO/AUI/NSF

    A single, ghostly subatomic particle that traveled some 4 billion light-years before reaching Earth has helped astronomers pinpoint a likely source of high-energy cosmic rays for the first time. Subsequent observations with the National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA) [depicted below] have given the scientists some tantalizing clues about how such energetic cosmic rays may be formed at the cores of distant galaxies.

    On September 22, 2017, an observatory called IceCube, made up of sensors distributed through a square kilometer of ice under the South Pole, recorded the effects of a high-energy neutrino coming from far beyond our Milky Way Galaxy.

    U Wisconsin ICECUBE neutrino detector at the South Pole

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    Neutrinos are subatomic particles with no electrical charge and very little mass. Since they interact only very rarely with ordinary matter, neutrinos can travel unimpeded for great distances through space.

    Follow-up observations with orbiting and ground-based telescopes from around the world soon showed that the neutrino likely was coming from the location of a known cosmic object — a blazar called TXS 0506+056, about 4 billion light-years from Earth.

    3

    Like most galaxies, blazars contain supermassive black holes at their cores. The powerful gravity of the black hole draws in material that forms a hot rotating disk. Jets of particles traveling at nearly the speed of light are ejected perpendicular to the disk. Blazars are a special class of galaxies, because in a blazar, one of the jets is pointed almost directly at Earth.

    Theorists had suggested that these powerful jets could greatly accelerate protons, electrons, or atomic nuclei, turning them into the most energetic particles known in the Universe, called ultra-high energy cosmic rays. The cosmic rays then could interact with material near the jet and produce high-energy photons and neutrinos, such as the neutrino detected by IceCube.

    Cosmic rays were discovered in 1912 by physicist Victor Hess, who carried instruments in a balloon flight. Subsequent research showed that cosmic rays are either protons, electrons, or atomic nuclei that have been accelerated to speeds approaching that of light, giving some of them energies much greater than those of even the most energetic electromagnetic waves. In addition to the active cores of galaxies, supernova explosions are probable sites where cosmic rays are formed. The galactic black-hole engines, however, have been the prime candidate for the source of the highest-energy cosmic rays, and thus of the high-energy neutrinos resulting from their interactions with other matter.

    “Tracking that high-energy neutrino detected by IceCube back to TXS 0506+056 makes this the first time we’ve been able to identify a specific object as the probable source of such a high-energy neutrino,” said Gregory Sivakoff, of the University of Alberta in Canada.

    Following the IceCube detection, astronomers looked at TXS 0506+056 with numerous telescopes and found that it had brightened at wavelengths including gamma rays, X-rays, and visible light. The blazar was observed with the VLA six times between October 5 and November 21, 2017.

    “The VLA data show that the radio emission from this blazar was varying greatly at the time of the neutrino detection and for two months afterward. The radio frequency with the brightest radio emission also was changing,” Sivakoff said.

    TXS 0506+056 has been monitored over a number of years with the NSF’s Very Long Baseline Array (VLBA), a continent-wide radio telescope system that produces extremely detailed images. The high-resolution VLBA images have shown bright knots of radio emission that travel outward within the jets at speeds nearly that of light. The knots presumably are caused by denser material ejected sporadically through the jet.

    “The behavior we saw with the VLA is consistent with the emission of at least one of these knots. It’s an intriguing possibility that such knots may be associated with generating high-energy cosmic rays and thus the kind of high-energy neutrino that IceCube found,” Sivakoff said.

    The scientists continue to study TXS 0506+056. “There are a lot of exciting phenomena going on in this object,” Sivakoff concluded.

    “The era of multi-messenger astrophysics is here,” said NSF Director France Córdova. “Each messenger — from electromagnetic radiation, gravitational waves and now neutrinos — gives us a more complete understanding of the Universe, and important new insights into the most powerful objects and events in the sky. Such breakthroughs are only possible through a long-term commitment to fundamental research and investment in superb research facilities.”

    Sivakoff and numerous colleagues from institutions around the world are reporting their findings in the journal Science.

    See the full article here .


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    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 1:39 pm on July 12, 2018 Permalink | Reply
    Tags: CfA/VERITAS a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV - TeV energy range Located at Fred Lawrence Whipple Observatory M, , , , U Wisconsin IceCube and IceCube Gen-2, VERITAS array has confirmed the detection of gamma rays from the vicinity of a supermassive black hole   

    From CfA: “VERITAS Supplies Critical Piece to Neutrino Discovery Puzzle” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    July 12, 2018
    Megan Watzke
    Harvard-Smithsonian Center for Astrophysics
    +1 617-496-7998
    mwatzke@cfa.harvard.edu

    Peter Edmonds
    Harvard-Smithsonian Center for Astrophysics
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    The VERITAS array has confirmed the detection of gamma rays from the vicinity of a supermassive black hole. While these detections are relatively common for VERITAS, this black hole is potentially the first known astrophysical source of high-energy cosmic neutrinos, a type of ghostly subatomic particle.

    On September 22, 2017 the IceCube Neutrino Observatory, a cubic-kilometer neutrino telescope located at the South Pole, detected a high-energy neutrino of potential astrophysical origin. However, the observation of a single neutrino by itself is not enough for IceCube to claim the detection of a source. For that, scientists needed more information.

    Very quickly after the detection by IceCube was announced, telescopes around the world including VERITAS (which stands for the “Very Energetic Radiation Imaging Telescope Array System”) swung into action to identify the source. The VERITAS, MAGIC and H.E.S.S. gamma-ray observatories all looked at the neutrino position. In addition, two gamma-ray observatories that monitor much of the sky at lower and higher energies also provided coverage.

    These follow-up observations of the rough IceCube neutrino position suggest that the source of the neutrino is a blazar, which is a supermassive black hole with powerful outflowing jets that can change dramatically in brightness over time. This blazar, known as TXS 0506+056, is located at the center of a galaxy about 4 billion light years from Earth.

    Initially, NASA’s Fermi Gamma-ray Space Telescope observed that TXS 0506+056 was several times brighter than usually seen in its all-sky monitoring. Eventually, the MAGIC observatory made a detection of much higher-energy gamma rays within two weeks of the neutrino detection, while VERITAS, H.E.S.S. and HAWC did not see the blazar in any of their observations during the two weeks following the alert.

    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain, Altitude 2,200 m (7,200 ft)

    Given the importance of higher-energy gamma-ray detections in identifying the possible source of the neutrino, VERITAS continued to observe TXS 0506+056 over the following months, through February 2018, and revealed the source but at a dimmer state than what was detected by MAGIC.

    “The VERITAS detection shows us that the gamma-ray brightness of the source changes, which is a signature of a blazar,” said Wystan Benbow of the Smithsonian Astrophysical Observatory (SAO) that operates and manages VERITAS, and the Principal Investigator of VERITAS operations. “Finding a link between an astrophysical source and a neutrino event could open yet another window of exploration to the extreme Universe.”

    The detection of gamma rays coincident with neutrinos is tantalizing, since both particles must be produced in the generation of cosmic rays. Since they were first detected over one hundred years ago, cosmic rays — highly energetic particles that continuously rain down on Earth from space — have posed an enduring mystery. What creates and launches these particles across such vast distances? Where do they come from?

    “The potential connection between the neutrino event and TXS 0506+056 would shed new light on the acceleration mechanisms that take place at the core of these galaxies, and provide clues on the century-old question of the origin of cosmic rays,” said co-author and spokesperson of VERITAS Reshmi Mukherjee of Barnard College, Columbia University in New York, New York.

    “The era of multi-messenger astrophysics is here,” said NSF Director France Córdova. “Each messenger – from electromagnetic radiation, gravitational waves and now neutrinos – gives us a more complete understanding of the universe, and important new insights into the most powerful objects and events in the sky. Such breakthroughs are only possible through a long-term commitment to fundamental research and investment in superb research facilities.”

    “The detection of very-high-energy gamma-rays from TXS 0506+056 with VERITAS provides vital information to understand the powerful processes taking place in this and other potential neutrino sources,” said co-author Marcos Santander of the University of Alabama in Tuscaloosa, who led the study. “The deep interconnection between neutrinos and gamma-rays is allowing us, for the first time, to study astrophysical objects using multimessenger observations in a way that would be impossible using single messengers.”

    A paper describing the deep VERITAS observations of TXS 0506+056 (“VERITAS Observations of the BL Lac Object TXS 0506+056”) is accepted for publication in The Astrophysical Journal Letters and appears online on July 12, 2018 (the accepted version is available here). A paper on the IceCube and initial gamma-ray observations, including VERITAS’s, appears in the latest issue of the journal Science.

    VERITAS is a ground-based facility located at the SAO’s Fred Lawrence Whipple Observatory in southern Arizona. It consists of an array of four 12-meter optical telescopes that can detect gamma rays via the extremely brief flashes of blue “Cherenkov” light created when gamma rays are absorbed in the Earth’s atmosphere. The VERITAS Collaboration consists of about 80 scientists from 20 institutions in the United States, Canada, Germany and Ireland.

    See the full article here .
    See also From Astronomy Magazine: “A cosmic particle spewed from a distant galaxy strikes Earth


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 2:03 pm on April 12, 2018 Permalink | Reply
    Tags: , Heavy dark matter and PeV neutrinos: are they related?, , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube: “Heavy dark matter and PeV neutrinos: are they related?” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube neutrino detector interior

    IceCube Gen-2 DeepCore

    The existence of dark matter was proposed to explain gravitational effects of objects such as galaxies that could not be described by the constituents of so-called “normal” matter—electrons, neutrons, and protons. But dark matter searches have so far been futile. A proposed solution is a new, heavy dark matter particle that is long-lived but not necessarily on cosmic timescales.

    This scenario is especially interesting for IceCube because the decay of dark matter can produce high-energy neutrinos. And some models predict that some or all of the highest energy neutrinos seen in IceCube could be the result of such decay.

    The IceCube Collaboration has tested a few of these models and found no evidence that the high-energy neutrinos can be attributed to the decay of heavy dark matter particles. This nondetection resulted in a new lower limit of seconds—about 10 billion times the age of the universe—for the lifetime of dark matter particles with a mass of 10 TeV or above. The paper [Search for neutrinos from decaying dark matter with IceCube,” The IceCube Collaboration: M. G. Aartsen et al.] summarizing these results has just been submitted to the European Physical Journal C.

    1
    Comparison of the lower lifetime limits with results obtained from gamma-ray telescopes: HAWC (Dwarf Spheroidal Galaxies), HAWC (Galactic Halo/Center) and Fermi/LAT. Image: IceCube Collaboration

    HAWC High Altitude Cherenkov Experiment, located on the flanks of the Sierra Negra volcano in the Mexican state of Puebla at an altitude of 4100 meters, at WikiMiniAtlas 18°59′41″N 97°18′30.6″W. searches for cosmic rays

    NASA/Fermi Gamma Ray Space Telescope


    NASA/Fermi LAT

    Following the current understanding of fundamental interactions, all matter is unstable—even protons are expected to decay, although we might never see the decay of one since its lifetime is about times the age of the universe.

    Relic particles that may make up galactic and extragalactic dark matter could have lifetimes short enough to allow us detect the high-energy neutrinos that they would inevitably produce. Indeed, several theoretical models ascribe the cosmic neutrino signal detected by IceCube at TeV-PeV energies to the decay of heavy dark matter.

    IceCube searched for heavy dark matter in two independent measurements—one using six years of muon-neutrino tracks from the Northern Hemisphere and the other using two years of all-flavor neutrino cascades from the full sky—and found that if dark matter neutrinos exist, then only 1 in every 10 billion dark matter particles could have decayed by now. These results also prove that IceCube is a high-precision particle detector that can rule out, or at least constrain, dark matter theoretical models.

    IceCube data has been fitted with different combinations of theoretical predictions for dark matter and a diffuse astrophysical component. “Using both tracks and cascades, data favors a small but nonsignificant contribution from dark matter,” explains Jöran Stettner, a graduate student at RWTH Aachen University in Germany and main author of this work. “However, adding a dark matter contribution does not significantly improve the description of the observed astrophysical neutrinos,” adds Stettner

    This nondetection is used to set the strongest bounds to date on the minimal lifetime of dark matter particles with masses above 10 TeV. “To explain that we have not seen neutrinos from the decay of heavy dark matter, the lifetime of the hypothetical particle has to be much larger than the age of the universe,” says Hrvoje Dujmovic, a graduate student from Sungkyunkwan University in Korea and also main author of this paper.

    See the full article here .

    Please help promote STEM in your local schools.

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    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 2:06 pm on March 16, 2018 Permalink | Reply
    Tags: , , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube: “A boost to precision measurements in the neutrino sector” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube neutrino detector interior

    IceCube Gen-2 DeepCore

    16 Mar 2018
    Sílvia Bravo

    While ubiquitous atmospheric neutrinos are usually considered as background in many IceCube analyses, they allow for precision measurements of the neutrino properties that were once the realm of large particle physics experiments like the ones at CERN and Fermilab or of neutrino detectors devoted to studying neutrino oscillations with the best accuracy.

    With better and larger neutrino telescopes in the horizon, researchers are now designing more efficient analysis techniques that will boost our understanding of neutrinos and advance searches for new physics including additional neutrino flavors or new interactions. These techniques not only provide more accurate and robust results, but also reduce expenses and time in computation that could limit improvements in the design of new detectors or the discovery potential of existing facilities. Details of these new techniques are given in a paper by the IceCube-Gen2 Collaboration submitted this week to Computer Physics Communications.

    1
    Estimated sensitivity to the neutrino mass ordering vs. sample size for direct histogramming, direct kernel density estimation (KDE), and the proposed staged smoothing methods applied to multiple statistically independent toy Monte Carlo sets. Vertical lines indicate central 68% quantiles. The dashed horizontal line shows the significance obtained from truth templates based on the parametric toy detector model. The staged approach outperforms the other methods—both in terms of bias and variance—for most samples, with direct histogramming only matching the staged approach using the largest samples. Note that no data points exist for direct KDE and large sample sizes as computational processing times become impractically large. Image: IceCube-Gen2 Collaboration.

    When trying to understand neutrino interactions in or around IceCube, scientists compare what we know with what nature is telling us, i.e., what our theories predict with what our detector measures. As it happens in competitive sports, where the transition from great performance to perfection and victory requires more advanced techniques, moving from the first great measurements to the best measurements ever drives the design of new state-of-the-art analysis.

    Neutrinos have been shown to be extremely interesting particles that could potentially unlock evidence for predicted—and maybe also unpredicted—new physics. The fact that neutrinos oscillate, or morph from one type to another as they travel through space and matter, was the first observation of a quantum effect at large scales. And years after this discovery, physicists are still trying to figure out what these oscillations can tell us about matter and whether these fleeting neutrinos can also reveal the properties of new physics such the nature of dark matter or the existence of still unknown laws of physics.

    Nature provides huge numbers of neutrinos and, thanks to its denser infill array DeepCore, IceCube can now perform very precise measurements of the neutrinos interacting near or in the detector. Future extensions of IceCube, known as IceCube-Gen2, as well as other neutrino telescopes in water will push these measurements to the next level of accuracy.

    The uncertainty about the workings of nature propagates into a set of different parameters and models in our theories. To prove which one is correct or at least rule out those that are not correct, scientists need to produce simulations at the level of precision at which the effects of these theories can be measured. Thus, if nature is providing us with tens of thousands of neutrinos, even millions of them, we need to produce large samples of simulated events to be tuned to the specifics of every single and relevant theory. In addition, we need to mimic how these theoretical predictions are changed by the design and performance of our detector.

    For an experiment like IceCube, and for other very large neutrino detectors to come, these simulations require an outlandish amount of computing resources. The larger the detector and the more accurate the measurement, the more critical it is what computers can do in a reasonable amount of time, the point that a lack of simulations could delay or even prevent an analysis, thus maybe a discovery.

    The new techniques that IceCube researchers present in the paper now on arXiv reduce the amount of simulation computation by dividing the production into four phases or stages: i) theoretical predictions of nonoscillated neutrinos; ii) adding oscillation effects, which change the flavor content of the sample; iii) integrating the effects of the detector, i.e., taking into account the probability that a given neutrino interacts in or near the detector and is later selected as an interesting event for a specific analysis; and iv) reconstruction, i.e., the transformation of raw data into the physical properties of the events.

    2
    Final-level templates used for the example data analysis. The reference distributions (truth) obtained directly for the toy detector model parameterizations are shown in panel (a). Given the same sample events the estimated distributions using histograms are shown in panel (b), using KDEs inpanel (c), and using the staged approach in panel (d). Image: IceCube-Gen2 Collaboration.

    The trick is in calculating and applying the physics and detector effects not on each individual event, but on groups of events that have similar enough properties. To group the events, a dense but finite grid is used, which can be optimized depending on, for example, the symmetries of the detector or the specific properties we want to measure. They also use improved interpolation and smoothening techniques, which allow to go from one stage to the next one by applying a transformation to the output of the previous stage. More standard techniques rely on calculating a weight for every individual simulated event and for every scenario—set of parameters—considered.

    “These techniques have been vital for studying and optimizing the performance of the upcoming IceCube low-energy upgrade program. Without them, we’d probably still be computing for the next couple of years,” explains Sebastian Böser, an IceCube researcher at the University of Mainz and one of the lead authors of this work.

    The authors used this new technique in studies to measure the sensitivity to the neutrino mass ordering in neutrino oscillations for the planned lower energy extension of IceCube. These studies yield more accurate and robust results with a reduction of two orders of magnitude in the amount of simulations produced.

    “We hope this paper will help in the understanding of how IceCube upgrade studies are performed, and that the described methods could be of use to other people in the community,” says Philipp Eller, a postdoctoral researcher at Penn State University and also a lead author of this paper.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    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 3:04 pm on March 3, 2018 Permalink | Reply
    Tags: Active galaxy TXS 0506 + 056, , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From IAC: Discovered the origin of the neutrino detected in the “Ice Cube” at the South Pole.” 

    IAC

    Instituto de Astrofísica de Canarias – IAC

    1
    Region of sky that is the emitting source of the neutrino.

    They use the Gran Telescopio Canarias (GTC) to calculate the distance to the object that emitted the extremely energetic neutrino detected last September thanks to experiment “IceCube”, installed in Antarctica is.

    One type of galaxies are called active (AGN) of which, besides the starlight that compose, receive radiation at all frequencies of the spectrum (from radio to gamma rays, passing of course, by light emitted by stars that compose them). Physical processes taking place in the nucleus of these galaxies are so extreme that produce many other highly energetic particles, such as neutrino. These are the most abundant subatomic particles in the universe that are everywhere, but they are very slippery. Although they are constantly bombarding the Earth, moving as fast as light, we can not see or feel them. They are “ghost” particles that rarely interact with matter and yet are fundamental to understand the laws of nature. Detect neutrinos requires, therefore, special instruments, such as the experimentIceCube , installed at the South Pole, which uses a huge ice cube with a size of 1 km long, 1 km wide and 1 km deep, as a sensor to locate these particles.

    On September 22, 2017, researchers from this particular observatory announced the detection of an extremely energetic neutrino coming from an area outside the Milky Way. The news spread rapidly causing a race to identify the source responsible for this issue, which by the high – energy neutrino detected had to be an active galaxy capable of emitting gamma rays. The satellite FERMI and MAGIC telescope, installed at the Observatorio del Roque de los Muchachos (Garafía, La Palma), were the first to be activated to look for sources of such radiation within the region expected sky.


    NASA/Fermi Gamma Ray Space Telescope

    MAGIC Cherenkov gamma ray telescope on the Canary island of La Palma, Spain

    They found that the active galaxy TXS 0506 + 056 was responsible for this issue and for the first time, it was possible to associate the emission of extragalactic neutrinos to a known source. However, the distance that he was was unknown, so it still could not deduct the brightness of the source, nor the physical processes responsible for the emission of neutrinos.

    2
    U Wisconsin IceCube at the South Pole
    Structure that houses the IceCube experiment. Superimposed, in the ice,
    a representation of how the developer detecting neutrinos.

    To measure, were spectroscopic observations needed with “conventional” telescopes, but all attempts failed because the signal was too weak. So a team of researchers led by astrophysicist Simona Paiano, the Observatory of Padova INAF (Instituto Nazionale di Astrofisica ) and Riccardo Scarpa, an astronomer at the GTC, decided to observe this source with the largest optical-infrared telescope in the world, ie the Gran Telescopio Canarias in La Palma. the results were recently published in the journal The Astrophysical journal.

    “Thanks to the enormous light collecting area of ​​the GTC, and after spending several hours of observation, could detect the typical features of the emission of gas in the galaxy, and thus determine its distance,” explains Paiano. In this way, they managed to place this active at a distance of 6000 million light years from Earth galaxy. “We saw the weak emission of gas where others saw nothing, a result that would not have been possible without the power of the GTC and experience of its staff,” adds Scarpa.

    “Credible association of a source as an emitter of neutrinos extremely high energy, located thousands of millions of light years away, opens a new window in astronomy to study the universe of the highest energies and, most importantly, use a messenger than light, “says Simona Paiano.

    Article: Paiano, S. et al. The redshift BL Lac object of the TXS 0506 + 056, The Astrophysical Journal Letters. http://lanl.arxiv.org/pdf/1802.01939v1

    See the full article here.

    Please help promote STEM in your local schools.

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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, at an altitude of 2,396 m (7,861 ft)

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.


    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

     
  • richardmitnick 5:40 pm on February 13, 2018 Permalink | Reply
    Tags: , , , , , The case of the disappearing neutrinos, U Wisconsin IceCube and IceCube Gen-2   

    From CERN Courier: “The case of the disappearing neutrinos” 


    CERN Courier

    1
    Neutrino energy

    Neutrinos are popularly thought to penetrate everything owing to their extremely weak interactions with matter. A recent analysis by the IceCube neutrino observatory at the South Pole proves this is not the case, confirming predictions that the neutrino–nucleon interaction cross section rises with energy to the point where even an object as tiny as the Earth can stop high-energy neutrinos in their tracks.


    U Wisconsin ICECUBE neutrino detector at the South Pole

    By studying a sample of 10,784 neutrino events, the IceCube team found that neutrinos with energies between 6.3 and 980 TeV were absorbed in the Earth. From this, they concluded that the neutrino–nucleon cross-section was 1.30+0.21–0.19 (stat) +0.39–0.43 (syst) times the Standard Model (SM) cross-section in that energy range. IceCube did not observe a large increase in the cross-section as is predicted in some models of physics beyond the SM, including those with leptoquarks or extra dimensions.

    The analysis used the 1km 3 volume of IceCube to collect a sample of upward-going muons produced by neutrino interactions in the rock and ice below and around the detector, selecting 10,784 muons with an energy above 1 TeV. Since the zenith angles of these neutrinos are known to about one degree, the absorber thickness can be precisely determined. The data were compared to a simulation containing atmospheric and astrophysical neutrinos, including simulated neutrino interactions in the Earth such as neutral-current interactions. Consequently, IceCube extended previous accelerator measurements upward in energy by several orders of magnitude, with the result in good agreement with the SM prediction (see figure, above).

    Neutrinos are key to probing the deep structure of matter and the high-energy universe, yet until recently their interactions had only been measured at laboratory energies up to about 350 GeV. The high-energy neutrinos detected by IceCube, partially of astrophysical origin, provide an opportunity to measure their interactions at higher energies.

    In an additional analysis of six years of IceCube data, Amy Connolly and Mauricio Bustamante of Ohio State University employ an alternative approach which uses 58 IceCube-contained events (in which the neutrino interaction took place within the detector) to measure the neutrino cross-section. Although these events mostly have well-measured energies, their neutrino zenith angles are less well known and they are also much less numerous, limiting the statistical precision.

    Nevertheless, the team was able to measure the neutrino cross-section in four energy bins from 18 TeV to 2 PeV with factor-of-ten uncertainties, showing for the first time that the energy dependence of the cross section above 18 TeV agrees with the predicted softer-than-linear dependence and reaffirming the absence of new physics at TeV energy scales.

    Future analyses from the IceCube Collaboration will use more data to measure the cross-sections in narrower bins of neutrino energy and to reach higher energies, making the measurements considerably more sensitive to beyond-SM physics. Planned larger detectors such as IceCube-Gen2 and the full KM3NeT can push these measurements further upwards in energy, while even larger detectors would be able to search for the coherent radio Cherenkov pulses produced when neutrinos with energies above 1017 eV interact in ice.

    Proposals for future experiments such as ARA and ARIANNA envision the use of relatively-inexpensive detector arrays to instrument volumes above 100 km3, enough to measure “GZK” neutrinos produced when cosmic-rays interact with the cosmic-microwave background radiation. At these energies, the Earth is almost opaque and detectors should be able to extend cross-section measurements above 1019 eV, thereby probing beyond LHC energies.

    These analyses join previous results on neutrino oscillations and exotic particle searches in showing that IceCube can also contribute to nuclear and particle physics, going beyond its original mission of studying astrophysical neutrinos.

    See the full article here .

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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

     
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