Tagged: Neutrinos Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 5:25 pm on August 20, 2015 Permalink | Reply
    Tags: , , Neutrinos   

    From IceCube: “IceCube confirms the astrophysical nature of high-energy neutrinos with an independent search in the Northern Hemisphere” 

    icecube
    IceCube South Pole Neutrino Observatory

    20 Aug 2015
    IceCube Collaboration

    Francis Halzen, PI IceCube
    University of Wisconsin-Madison
    francis.halzen@icecube.wisc.edu

    Olga Botner
    Professor of Physics
    University of Uppsala
    olga.botner@physics.uu.se

    Today, the IceCube Collaboration announces a new observation of high-energy neutrinos that originated beyond our solar system. This study, which looked for neutrinos coming from the Northern Hemisphere, confirms their cosmic origin as well as the presence of extragalactic neutrinos and the intensity of the neutrino rate. The first evidence for astrophysical neutrinos was announced by the collaboration in November 2013. The results published now in Physical Review Letters are the first independent confirmation of this discovery.

    “Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy, and with this paper, it delivered,” says Francis Halzen, principal investigator of IceCube and the Hilldale and Gregory Breit Distinguished Professor of Physics at the University of Wisconsin–Madison. “It is not quite CMS and ATLAS, but this is as close to an independent confirmation as one can get with a single instrument.”

    1
    This image shows one of the highest-energy neutrino events of this study superimposed on a view of the IceCube Lab (ICL) at the South Pole. Image: IceCube Collaboration

    Neutrinos are subatomic particles that travel throughout the universe almost undisturbed by matter, pointing directly to the sources where they were created. And for the highest energy neutrinos, those sources are expected to be the most extreme environments in the universe: powerful cosmic generators, such as black holes or massive exploding stars, that are able to accelerate cosmic rays to energies over a million times the energies achieved by record-breaking human-made accelerators, such as the LHC at CERN.

    “Cosmic neutrinos are the key to yet unexplored parts of our universe and might be able to finally reveal the origins of the highest energy cosmic rays, including the rare ‘Oh-My-God’ particles,” says collaboration spokesperson Olga Botner, of Uppsala University. “The discovery of astrophysical neutrinos hints at the dawn of a new era in astronomy.”

    Neutrinos are never directly observed, but IceCube is able to see the by-products of a neutrino interaction with the Antarctic ice. This cubic-kilometer detector records a hundred thousand neutrinos every year, most of them produced by the interaction of cosmic rays with the Earth’s atmosphere. Billions of atmospheric muons created in the same interactions also leave traces in IceCube. And from all of these, researchers are looking for only a few dozen astrophysical neutrinos, which will expand our current understanding of the universe.

    The search presented today by the IceCube Collaboration uses an old strategy for a neutrino telescope: it looks at the universe through the Earth, using our planet to filter the large background of atmospheric muons. More than 35,000 neutrinos were found in data recorded between May 2010 and May 2012. At the highest energy, above 100 TeV, the measured rate cannot be explained by neutrinos produced in the Earth’s atmosphere, indicating the astrophysical nature of high-energy neutrinos. The analysis presented in this paper suggests that more than half of the 21 neutrinos above 100 TeV are of cosmic origin.

    This independent observation, with a significance of 3.7 sigma and in good agreement with previous results by the IceCube Collaboration, also confirms the high rate of astrophysical neutrinos. Even though scientists are still counting them by the handful, IceCube results are close to the maximum rates based on potential cosmic ray sources. The intensity of this flux shows that cosmic ray sources are also efficient generators of neutrinos. And, therefore, these tiny particles are further endorsed as the perfect tools to explore the extreme universe.

    3
    Sky map in equatorial coordinates of the arrival direction of the 21 highest-energy events of this analysis (red dotted circles). The most probable neutrino energy (in TeV) indicated for each event assumes the best-fit astrophysical flux of the analysis. For comparison, the events of the 3-year high-energy starting event (HESE) analysis with deposited energy larger than 60 TeV (tracks and cascades) are also shown. Cascade events are indicated together with their median angular uncertainty (thin circles). Image: IceCube Collaboration

    The observed high-energy neutrinos are a brand-new neutrino sample, with only one event in common with the first results announced in 2013, which searched for high-energy neutrinos that had interacted with the ice inside IceCube during the same data-taking period. The current search looked for muon neutrinos only. These neutrinos produce a muon when they interact with the ice and have a characteristic signature in IceCube, called a track, that makes them easy to identify. The same shape is expected for an atmospheric muon, but by looking only at the Northern Hemisphere, researchers know that a detected muon could have only been produced by a neutrino interaction.

    These neutrino-induced tracks have a very good pointing resolution, in which they can locate their sources within less than a degree. However, IceCube’s studies have not yet found a significant number of neutrinos coming from any single source. The neutrino flux measured by IceCube in the Northern Hemisphere has the same intensity as the astrophysical flux in the Southern Hemisphere. This adds support to a large population of extragalactic sources, since otherwise sources in the Milky Way would dominate the flux around the galactic plane.

    In addition, this new high-energy neutrino sample, when combined with previous IceCube measurements, allows the most accurate measurements to date of the energy spectrum and neutrino-type composition of the extraterrestrial neutrino flux. Those results are published in an accompanying paper in The Astrophysical Journal.

    IceCube, run by the international IceCube Collaboration and headquartered at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) at UW–Madison, is a gigaton particle detector located near the Amundsen-Scott South Pole Station, one of the scientific facilities in Antarctica managed by NSF. It is buried beneath the surface, extending to a depth of about 2,500 meters. A surface array, IceTop, and a denser inner subdetector, DeepCore, significantly enhance the capabilities of the observatory, making it a multipurpose facility.

    The IceCube Neutrino Observatory was built under an NSF Major Research Equipment and Facilities Construction grant, with assistance from partner funding agencies around the world. The NSF’s Division of Polar Programs and Physics Division continue to support the project with a Maintenance and Operations grant, along with international support from participating institutions and their funding agencies. UW–Madison is the lead institution, and the international collaboration includes 300 physicists and engineers from the U.S., Germany, Sweden, Belgium, Switzerland, Japan, Canada, New Zealand, Australia, U.K., Korea and Denmark.

    + info Evidence for Astrophysical Muon Neutrinos from the Northern Sky with IceCube, IceCube Collaboration: M.G. Aartsen et al. Physical Review Letters 115, 081102 (2015).

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 1:13 pm on August 14, 2015 Permalink | Reply
    Tags: , , Neutrinos   

    From Nature: “Age of the neutrino: Plans to decipher mysterious particle take shape” 

    Nature Mag
    Nature

    12 August 2015
    Elizabeth Gibney

    A graphical guide to four giant experiments spread across the world.

    As researchers at CERN, Europe’s particle-physics laboratory near Geneva, dream of super-high-energy colliders to explore the Higgs boson, their counterparts in other parts of the world are pivoting towards a different subatomic entity: the neutrino.

    Neutrinos are more abundant than any particle other than photons, yet they interact so weakly with other matter that every second, more than 100 billion stream — mainly unnoticed — through every square centimetre of Earth. Once thought to be massless, they in fact have a minuscule mass and can change type as they travel, a bizarre and entirely unexpected feature that physicists do not fully understand (see ‘An unconventional particle’). Indeed, surprisingly little is known about the neutrino. “These are the most ubiquitous matter particles in the Universe that we know of, and probably the most mysterious,” says Nigel Lockyer, director of the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois.

    FNAL II photo
    FNAL

    2

    Four unprecedented experiments look poised to change this. Two — one in China and one in India — already have the go-ahead, and plans to erect detectors in Japan and the United States are in the works.

    3
    Graphic by Nigel Hawtin

    The results are expected to feed into some of the most fundamental questions in cosmology. Some of the experiments will make their own neutrinos; all will use any they can capture from the Sun or from supernova explosions. “The age of the neutrino,” Lockyer says, “could go on for a very long time.”

    Flurry of experiments

    The detectors in China (JUNO) and India (INO) are designed to untangle the relationship between the three mass states, with implications for the origins of the forces of nature. By contrast, DUNE in the United States and Hyper-Kamiokande in Japan aim to spot differences in how neutrinos and antineutrinos oscillate between flavours. That could solve a second cosmological puzzle: why the Universe is made up of matter rather than antimatter. All four detectors will also hunt for a hypothesized ‘sterile’ neutrino.

    JUNO Neutrino detector China
    JUNO Neutrino Detector

    INO Indian Neutrino detector
    INO Neutrino Detector

    FNAL Dune & LBNF
    FNAL/DUNE

    Hyper-Kamiokande
    Hyper-Kamiokande

    4

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

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

     
  • richardmitnick 12:35 pm on August 14, 2015 Permalink | Reply
    Tags: , , , Neutrinos   

    From FNAL: “Muon neutrinos make a disappearance” 

    FNAL II photo

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

    Aug. 14, 2015
    Kirk Bays, California Institute of Technology

    1
    This plot shows the energy spectrum of detected muon neutrino events in the NOvA detector compared to the much larger signal that would be expected if there were no neutrino oscillations.

    Neutrinos are ghosts; everywhere around us, we unknowingly swim through billions of them constantly without ever interacting. Thankfully both natural and man-made sources such as the Fermilab NuMI beam produce copious numbers of higher-energy neutrinos.

    FNAL NUMI Tunnel project
    FNAL NuMI tunnel

    This abundance means that they can be spotted with very large detectors despite their ghostly nature. They come in three types and are known for their strange properties, such as their tendency to oscillate, or change from one type into another, similar to tossing a basketball and finding a mere ping pong ball where it lands.

    Oscillations depend on a neutrino’s energy and distance traveled, and by using a man-made neutrino beam we can carefully choose where we put our detectors in order to maximize this effect. This was done in NOvA, the U.S. flagship long-baseline neutrino experiment with a massive five-story, 14,000-ton far detector located in remote northern Minnesota, 500 miles from Fermilab, which only recently released the analysis results from its first batch of data.

    FNAL NOvA experiment
    NOvA

    FNAL Dune & LBNF
    DUNE

    NOvA looks for both the disappearance of muon type neutrinos (which make up the NuMI beam) as they oscillate away, and the appearance of electron type neutrinos that wouldn’t be there without oscillations. The included plot shows the energy distribution of muon neutrinos detected, where NOvA would expect to see 201 muon neutrinos if there were no oscillations, but only 33 were actually seen — clear evidence of oscillations.

    Muon neutrinos are detected by seeing muons resulting from their interactions, and one analysis challenge was to distinguish the muons from neutrinos from tens of millions of very similar looking cosmic ray muons. Only one or two of these 33 events are estimated to be cosmic rays surviving the sophisticated event selection, however.

    The shape of the energy distribution contains further information that allows extraction of precise parameters detailing the inner workings of the oscillations. These NOvA results are already competitive with the world’s best information on these parameters with less than 10 percent of the planned data, and this result will quickly improve.

    The information gleaned from these rare neutrino interactions has far-reaching implications and can teach us about things like the evolution of the universe, how a supernova works and possibly even why the universe is made of matter and not antimatter. We still have a long way to go in solving all their mysteries, but NOvA is a big step along the path to understanding these little ghosts all around us.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 12:03 pm on August 14, 2015 Permalink | Reply
    Tags: , Borexino detector, Neutrinos,   

    From IOP PhysicsWorld: “Physicists isolate neutrinos from Earth’s mantle for first time” 

    physicsworld
    physicsworld.com

    Aug 14, 2015
    Hamish Johnston

    1
    Seeing the light: some of Borexino’s many light detectors

    The first confirmed sightings of antineutrinos produced by radioactive decay in the Earth’s mantle have been made by researchers at the Borexino detector in Italy. While such “geoneutrinos” have been detected before, it is the first time that physicists can say with confidence that about half of the antineutrinos they measured came from the Earth’s mantle, with the rest coming from the crust. The Borexino team has also been able to make a new calculation of how much heat is produced in the Earth by radioactive decay, finding it to be greater than previously thought. The researchers say that in the future, the experiment should be able to measure the quantities of radioactive elements in the mantle as well.

    According to the bulk silicate Earth model (BSE) model, most of the radioactive uranium, thorium and potassium in our planet’s interior lies in the crust and mantle. Accounting for about 84% of our planet’s total volume, the mantle is the large rocky layer sandwiched between the crust and the Earth’s core. Heat flows from the interior of the Earth into space at a rate of about 47 TW, but one of the big mysteries of geophysics is how much of this heat is left over from when the Earth formed, and how much comes from the radioactive decay chains of uranium-238, thorium-232 and potassium-40.

    Peering deep underground

    One way to settle the question is to measure the antineutrinos produced by these decay chains. These tiny particles travel easily through the Earth, which means that detectors located near the surface could give geophysicists a way of measuring the abundance of radioactive elements deep within the Earth – and thus the heat produced deep underground.

    Back in 2005 physicists working on the KamLAND neutrino detector in Japan announced that they had detected 22 geoneutrinos, while Borexino, which has been running since 2007, reported in 2010 that it had seen 10 such particles.

    KamLAND
    KamLAND

    Both detectors have since spotted more geoneutrinos and, taken together, their measurements suggest that about one half of the heat flowing out of the Earth is generated by radioactive decay, although there is large uncertainty in this value.

    Italian adventure

    The Borexino detector is made up of 300 tonnes of an organic liquid, and is located deep beneath a mountain at Italy’s Gran Sasso National Laboratory to shield the experiment from unwanted cosmic rays that would otherwise drown out the neutrino signal.

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO
    Gran Sasso National Laboratory

    Whenever electrons in the liquid are struck by an antineutrino, they recoil and create a flash of light. In the latest work, Borexino physicists have analysed a total of 77 detector events, with the team calculating – using data from the International Atomic Energy Agency – that about 53 of these antineutrinos were produced by nuclear reactors.

    The remaining 24 geoneutrinos could have come from either the Earth’s crust or its core. However, scientists have a pretty good idea of how much uranium and thorium are in the crust, allowing the Borexino physicists to say that half of these geoneutrinos were produced in the mantle and the other half in the crust. Furthermore, the physicists can say with 98% confidence that they have detected mantle neutrinos – a much greater level of confidence than achieved in previous studies.

    The team also calculated the heat generated by radioactive decay in the Earth and found it to be in the 23–36 TW range. This is larger than estimates based on assumptions about the amount of radioactive elements in the Earth, which are in the 12–30 TW range, and also larger than an estimate based on previous antineutrino measurements.

    The Borexino team also tried to work out what proportion of the geoneutrinos came from the uranium decay chain and what proportion from the thorium chain. Potassium decays were not considered because they are not expected to make a significant contribution to the numbers detected. The data suggest that the currently accepted ratio of thorium to uranium in the Earth is correct, but that the uncertainty in the Borexino values is very large. More data, the Borexino physicists say, should let them make more precise measurements of the contributions of uranium and thorium to the heating of the Earth.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

     
  • richardmitnick 4:42 pm on August 12, 2015 Permalink | Reply
    Tags: , , Neutrinos,   

    From FNAL: “MicroBooNE sees first cosmic muons” 

    FNAL II photo

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

    Aug. 12, 2015
    Ali Sundermier

    1
    This image shows the first cosmic ray event recorded in the MicroBooNE TPC on Aug. 6. Image: MicroBooNE

    A school bus-sized detector packed with 170 tons of liquid argon has seen its first particle footprints.

    On Aug. 6, MicroBooNE , a liquid-argon time projection chamber, or LArTPC, recorded images of the tracks of cosmic muons, particles that shower down on Earth when cosmic rays collide with nuclei in our atmosphere.

    Temp 1
    MicroBooNE

    “This is the first detector of this size and scale we’ve ever launched in the U.S. for use in a neutrino beam, so it’s a very important milestone for the future of neutrino physics,” said Sam Zeller, co-spokesperson for the MicroBooNE collaboration.

    Picking up cosmic muons is just one brief stop during MicroBooNE’s expedition into particle physics. The centerpiece of the three detectors planned for Fermilab’s Short-Baseline Neutrino program, or SBN, MicroBooNE will pursue the much more elusive neutrino, taking data about this weakly interacting particle for about three years. When beam starts up in October, it will travel 470 meters and then traverse the liquid argon in MicroBooNE, where neutrino interactions will result in tracks that the detector can convert into precise three-dimensional images. Scientists will use these images to investigate anomalies seen in an earlier experiment called MiniBooNE, with the aim to determine whether the excess of low-energy events that MiniBooNE saw was due to a new source of background photons or if there could be additional types of neutrinos beyond the three established flavors.

    One of MicroBooNE’s goals is to measure how often a neutrino that interacts with an argon atom will produce certain types of particles. A second goal is to conduct R&D for future large-scale LArTPCs. MicroBooNE will carry signals up to two and a half meters across the detector, the longest drift ever for a LArTPC in a neutrino beam. This requires a very high voltage and very pure liquid argon. It is also the first time a detector will operate with its electronics submerged in liquid argon on such a large scale. All of these characteristics will be important for future experiments such as the Deep Underground Neutrino Experiment, or DUNE, which plans to use similar technology to probe neutrinos.

    “The entire particle physics community worldwide has identified neutrino physics as one of the key lines of research that could help us understand better how to go beyond what we know now,” said Matt Toups, run coordinator and co-commissioner for MicroBooNE with Fermilab Scientist Bruce Baller. “Those questions that are driving the field, we hope to answer with a very large LArTPC detector.”

    Another benefit of the experiment, Zeller said, is training the next generation of LArTPC experts for future programs and experiments. MicroBooNE is a collaborative effort of 25 institutions, with 55 students and postdocs working tirelessly to perfect the technology. Collaborators are keeping their eyes on the road toward the future of neutrino physics and liquid-argon technology.

    “It’s been a long haul,” said Bonnie Fleming, MicroBooNE co-spokesperson. “Eight and a half years ago liquid argon was a total underdog. I used to joke that no one would sit next to me at the lunch table. And it’s a world of difference now. The field has chosen liquid argon as its future technology, and all eyes are on us to see if our detector will work.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 6:27 am on August 8, 2015 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “Fermilab experiment sees neutrinos change over 500 miles” 

    FNAL II photo

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

    Aug. 7, 2015
    Media contact:
    Andre Salles, Fermilab Office of Communication, media@fnal.gov, 630-840-3351

    Science contacts:
    Mark Messier, NOvA co-spokesperson, messier@indiana.edu, 812-855-0236
    Peter Shanahan, NOvA co-spokesperson, shanahan@fnal.gov, 630-840-8378

    1
    Illustration: Fermilab/Sandbox Studio

    Scientists on the NOvA experiment saw their first evidence of oscillating neutrinos, confirming that the extraordinary detector built for the project not only functions as planned but is also making great progress toward its goal of a major leap in our understanding of these ghostly particles.

    FNAL NOvA experiment
    NOvA map

    NOvA is on a quest to learn more about the abundant yet mysterious particles called neutrinos, which flit through ordinary matter as though it weren’t there. The first NOvA results, released this week at the American Physical Society’s Division of Particles and Fields conference in Ann Arbor, Michigan, verify that the experiment’s massive particle detector — 50 feet tall, 50 feet wide and 200 feet long — is sitting in the sweet spot and detecting neutrinos fired from 500 miles away. Scientists have sorted through millions of cosmic ray strikes and zeroed in on neutrino interactions.

    FNAL NOvA room
    NOvA

    “People are ecstatic to see our first observation of neutrino oscillations,” said NOvA co-spokesperson Peter Shanahan of the U.S. Department of Energy’s Fermi National Accelerator Laboratory. “For all the people who worked over the course of a decade on the designing, building, commissioning and operating this experiment, it’s beyond gratifying.”

    Researchers have collected data aggressively since February 2014, recording neutrino interactions in the 14,000-ton far detector in Ash River, Minnesota, while construction was still under way. This allowed the collaboration to gather data while testing systems before starting operations with the complete detector in November 2014, shortly after the experiment was completed on time and under budget. NOvA construction and operations are supported by the DOE Office of Science.

    The neutrino beam generated at Fermilab passes through an underground near detector, which measures the beam’s neutrino composition before it leaves the Fermilab site. The particles then travel more than 500 miles straight through the Earth, no tunnel required, oscillating (or changing types) along the way. About once per second, Fermilab’s accelerator sends trillions of neutrinos to Minnesota, but the elusive neutrinos interact so rarely that only a few will register at the far detector.

    When a neutrino bumps into an atom in the NOvA detector, it releases a signature trail of particles and light depending on which type it is: an electron, muon or tau neutrino. The beam originating at Fermilab is made almost entirely of one type — muon neutrinos — and scientists can measure how many of those muon neutrinos disappear over their journey and reappear as electron neutrinos.

    If oscillations did not occur, experimenters predicted they would see 201 muon neutrinos arrive at the NOvA far detector in the data collected; instead, they saw a mere 33, proof that the muon neutrinos were disappearing as they transformed into the two other flavors. Similarly, if oscillations did not occur, scientists expected to see only one electron neutrino appearance (due to background interactions). But the collaboration saw six such events, evidence that some of the missing muon neutrinos had turned into electron neutrinos.

    Similar long-distance experiments such as T2K in Japan and MINOS at Fermilab have seen these muon neutrino to electron neutrino oscillations before. NOvA, which will take data for at least six years, is seeing nearly equivalent results in a shorter time frame, something that bodes well for the experiment’s ambitious goal of measuring neutrino properties that have eluded other experiments so far.

    T2K
    T2K

    “One of the reasons we’ve made such excellent progress is the impressive Fermilab neutrino beam and accelerator team,” said NOvA co-spokesperson Mark Messier of Indiana University. “Having a beam of that power running so efficiently gives us a real competitive edge and allows us to gather data quickly.”

    Fermilab’s flagship accelerator recently set a high-energy neutrino beam world record when it reached 521 kilowatts, and the laboratory is working on improving the neutrino beam even further for projects such as NOvA and the upcoming Deep Underground Neutrino Experiment. Researchers expect to reach 700 kilowatts early next calendar year, accumulating a slew of neutrino interactions and tripling the amount of data recorded by year’s end.

    Neutrinos are the most abundant massive particle in the universe but are still poorly understood. While researchers know that neutrinos come in three types, they don’t know which is the heaviest and which is the lightest. Figuring out this ordering — one of the goals of the NOvA experiment — would be a great litmus test for theories about how the neutrino gets its mass. While the famed Higgs boson helps explain how some particles obtain their masses, scientists don’t know yet how it is connected to neutrinos, if at all. The measurement of the neutrino mass hierarchy is also crucial information for neutrino experiments trying to see if the neutrino is its own antiparticle.

    Like T2K, NOvA can also run in antineutrino mode, opening a window to see whether neutrinos and antineutrinos are fundamentally different. An asymmetry early in the universe’s history could have tipped the cosmic balance in favor of matter, making the world we see today possible. Soon, scientists will be able to combine the neutrino results obtained by T2K, MINOS and NOvA, yielding more precise answers about scientists’ most pressing neutrino questions.

    “The rapid success of the NOvA team demonstrates a commitment and talent for taking on complex projects to answer the biggest questions in particle physics,” said Fermilab Director Nigel Lockyer. “We’re glad that the detectors are functioning beautifully and providing quality data that will expand our understanding of the subatomic realm.”

    The NOvA collaboration comprises 210 scientists and engineers from 39 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom.

    For more information, visit the experiment’s website.
    Watch live particle events recorded by the NOvA experiment online.
    Follow the experiment on Facebook and Twitter.

    Note: NOvA stands for NuMI Off-Axis Electron Neutrino Appearance. NuMI is itself an acronym, standing for Neutrinos from the Main Injector, Fermilab’s flagship accelerator. The Fermilab Accelerator Complex is an Office of Science user facility.

    Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at http://www.fnal.gov, and follow us on Twitter at @Fermilab.

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

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 4:34 pm on August 7, 2015 Permalink | Reply
    Tags: , Borexino, KamLAND, Neutrinos,   

    From Physics: “Focus: Neutrinos Detected from the Earth’s Mantle” 

    Physics LogoAbout Physics

    Physics Logo 2

    Physics

    August 7, 2015
    Mark Buchanan

    1
    Neutrino Eyes. The Borexino experiment in Italy reports detecting 24 neutrinos produced by radioactive decay in the Earth over a seven-year period.

    KamLAND
    KamLAND

    The steady decay of long-lived radioactive isotopes within the Earth heats the planet and also sends out streams of neutrinos, which can be observed by large detectors. The Borexino Collaboration now reports a new set of data for such “geoneutrinos” and indicates that at least some of them originate from the Earth’s mantle. The work could improve researchers’ understanding of how radioactive decays help drive internal geophysical processes, including the slow convection of rock in the Earth’s mantle.

    Neutrinos are notorious for interacting with matter extremely rarely—a light-year-thick wall of lead would only stop half of the neutrinos flying through—so detection is challenging. But using large detectors, both Borexino and KamLAND, another international collaboration, have previously detected geoneutrinos with very high confidence. With more data, researchers hope to gain further information about the distribution of radioactive isotopes in the Earth’s interior and about the amount of heat they deliver to various subterranean regions.

    The Borexino detector, which contains 300 metric tons of a fluid that can emit light flashes in response to particles, operates at the underground Gran Sasso National Laboratory in Italy and detects electron antineutrinos, commonly created in nuclear decays. From December of 2007 through March of 2015, the detector recorded a total of 77 candidate geoneutrino events, compared with 46 events the team reported in 2013 [1].

    Of all known long-lived radioactive isotopes, only uranium-238 and thorium-232 are abundant enough and produce antineutrinos of sufficient energy to contribute significantly to detection events. However, nuclear reactors also generate antineutrinos. Using data from the International Atomic Energy Agency, the Borexino team calculated that about 53 of the 77 detected antineutrinos were likely to be from reactors, leaving about 24 true geoneutrinos. The certainty of this detection is the highest ever achieved for geoneutrinos; the chance that all of these particles come from reactors is less than one in a hundred million.

    The Borexino collaboration estimated the number of geoneutrinos originating from the Earth’s mantle, rather than from the crust. Their previous estimate had a large uncertainty and not very high confidence that any of the detected geoneutrinos came from the mantle. With the larger dataset, the team reduced the error bars enough to say with 98% confidence that they have detected mantle neutrinos. To find the fraction from the mantle, as before, they estimated the number of neutrinos expected from the crust based on the measured abundance of uranium and thorium and then subtracted this number from the total. They found that about half of the geoneutrinos most likely originated from the mantle.

    The researchers also estimated the total amount of heat generated by radioactive decays. Geoscientists know that the Earth generates about 47 terawatts of power from its interior, some from “primordial heat” left over from the Earth’s formation and the rest from radioactive decays. The fraction of heat attributable to each of these sources remains largely unknown. The new Borexino analysis gives an estimate for the radiogenic component of heating of about 33 terawatts (with large error bars)—higher than earlier studies.

    Borexino team leader Aldo Ianni, of the Gran Sasso Laboratory, suggests that future studies conducted over longer periods of time will reduce uncertainties and allow accurate geoneutrino spectroscopy—distinguishing neutrinos according to the element from which they originated. Such data would provide information on the distribution of isotopes throughout the Earth’s interior. The current study could just barely distinguish between antineutrinos coming from uranium-238 decays and those from thorium-232 decays, based on the particles’ energies. However, the uncertainties remain too large to make definitive statements.

    “For those of us in the field, this is very impressive progress,” says Jason Detwiler of the University of California at Berkeley, a member of the KamLAND group. “Their spectrum is very clean and beautifully and incontrovertibly demonstrates the presence of the geoneutrino signal.” Detwiler says that the number of mantle neutrinos seen by Borexino may have geophysical significance. ”The data are consistent with there being enough radiogenic heat to drive mantle convection,” he says, referring to the slow turnover of mantle material over geologic time.

    This research is published in Physical Review D.

    References

    1. G. Bellini et al. (Borexino Collaboration), Phys. Lett. B 722, 295. (2013) .

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
  • richardmitnick 12:32 pm on August 7, 2015 Permalink | Reply
    Tags: , , , Neutrinos   

    From FNAL “Frontier Science Result: NOvA sees electron neutrinos 

    FNAL II photo

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

    Aug. 7, 2015
    Alexander Radovic, College of William and Mary

    1
    This event in the NOvA far detector in Minnesota, shown from two different viewpoints, is a candidate electron neutrino interaction.

    Neutrino physicists have had a rich and storied relationship with the little neutral ones. First suggested by Wolfgang Pauli as a solution to the problem of missing energy in radioactive decay these light neutral particles have always proven to be as frustrating as they are fascinating. Pauli himself famously said, “I have done a terrible thing, I have postulated a particle that cannot be detected.”

    But detect it physicists did, and we found it to be even stranger than we first expected. Perhaps most fascinating is the fact that neutrinos change among the seemingly distinct types as they travel. Physicists around the world and at Fermilab have made much progress in understanding these neutrino oscillations, but key questions remain unanswered. Does the ordering of neutrino masses match our intuition based on what we know of other families of particles, or is it inverted? Do neutrinos oscillate the same as antineutrinos? These questions are themselves compelling and tie in to grander theories. For example, leptogenesis seeks to explain why our universe has far more matter than antimatter.

    Many experiments have worked to answer these questions. At Fermilab the NuMI muon neutrino beam enables a program of study of neutrino oscillations.

    FNAL NUMI Tunnel project
    FNAL NuMI muon neutrino beam tunnel

    Over the long journey from Fermilab to northern Minnesota, these neutrinos change type. The MINOS experiment has already used this beam to study the disappearance of muon neutrinos. The NOvA experiment is now providing another key piece of the puzzle by studying the appearance of electron neutrinos.

    FNAL NOvA experiment
    NOvA

    In many ways the entire NOvA experiment was optimized to see electron neutrino appearance. The detector has a high resolution and is instrumented with specialized photodetectors such that it can resolve the key signatures of an electron neutrino interaction. Excellent timing systems allow us to disentangle neutrino beam events from cosmic activity. The NuMI beam is operating at its highest-ever power to provide as many neutrinos as possible to the experiment, and the detector is off the main axis of the NuMI beam so it sees neutrinos at the perfect energy.

    The first measurement of electron neutrino appearance by NOvA has also required a complex analysis of our data, using sophisticated image processing algorithms trained on large sets of simulated data to pull out a pure sample of electron neutrino candidates and data-driven studies using beam and cosmic events at our near and far detectors. Four graduate students will earn their doctorates with their work on this result, and more have made significant contributions.

    The first appearance result, presented at Thursday’s Joint Experimental-Theoretical Seminar, shows six events selected with our primary analysis and 11 with our secondary analysis, with an expected background of approximately one in each case. This observation proves conclusively that the NOvA experiment can measure electron neutrino appearance and confirms oscillations at greater than 3 sigma with our primary analysis or 5 sigma with our secondary analysis. While this first result represents one-twelfth of the final exposure, it has already reached excellent agreement with measurements from existing experiments such as MINOS and T2K.

    NOvA has shown that it will be able to contribute significantly to the world’s knowledge of neutrino oscillations in the coming decade. It also represents a start of another exciting road as we set out to make the best possible use of world-class detectors and a world-class beam to provide leading discoveries using electron neutrino appearance.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 7:47 pm on August 4, 2015 Permalink | Reply
    Tags: , , Neutrinos,   

    From Symmetry: “IceCube sees highest-energy neutrino ever found” 

    Symmetry

    August 04, 2015
    Kathryn Jepsen

    Observations of this kind could lead scientists to the source of ultra-high-energy cosmic rays.

    https://i0.wp.com/www.symmetrymagazine.org/sites/default/files/styles/lead_image/public/images/standard/IceCube_Aurora.jpg
    Photo by Ian Rees, IceCube/NSF

    In 2013, the IceCube neutrino experiment at the South Pole reported the observation of two ultra-high-energy neutrino events, which they named after Sesame Street characters Bert and Ernie. Later, they found one more.

    It seems a fourth character has moved into the neighborhood. Today IceCube scientists reported the observation of an even higher-energy neutrino event, one that offers scientists the best hope yet that they will be able to use ultra-high-energy neutrinos to find the source of ultra-high-energy cosmic rays. The neutrino event had an energy of more than 2000 trillion electronvolts.

    “We have been adding to our previous analysis more years of data, and in an extra year we found this spectacular event,” says Francis Halzen, IceCube principle investigator for the University of Wisconsin, Madison.

    For more than a century, scientists have known that particles called cosmic rays rain down on the Earth from space. Some of these cosmic rays slam into our atmosphere at energies higher than we could possibly reach in any earthly particle accelerator. It is still a mystery where these particles come from, but it seems that they are from energetic sources outside our galaxy. One suspicion is that they are coming from active galaxies swirling around distant black holes.

    Cosmic rays are charged particles, which means that their paths bend and shift as they pass through magnetic fields in space. That makes it difficult to trace their origins.

    That’s where neutrinos come in. Neutrinos are neutral, rarely interacting particles that can pass through entire planets without changing course. Ultra-high-energy neutrinos that the IceCube experiment observes could be coming from the same sources as ultra-high-energy cosmic rays. If so, they could point the way back to those sources.

    “This opens the neutrino astronomy field,” says Fermilab neutrino scientist Anne Schukraft, a former member of the IceCube collaboration.

    Neutrinos come in three types, called flavors: electron, muon and tau. When electron and tau neutrinos interact with the ice around the IceCube neutrino detector, their energy appears to balloon out from their interaction points, making it difficult to figure out exactly where they came from.

    This latest ultra-high-energy neutrino, however, was a muon neutrino. When muon neutrinos interact, they release a muon, a heavy cousin of the electron that can travel straight through matter for several kilometers before running out of steam.

    In this case, a neutrino passed through the Earth and interacted somewhere outside of the IceCube detector. The muon it released passed through it, drawing a distinct line to show where it came from.

    From there, “Standard Model physics can run the movie backwards,” Halzen says.

    1
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    The muon they detected had an energy of more than 2000 trillion electronvolts; the neutrino that produced it likely had about three times that energy. The only known source of such a high-energy muon coming through the Earth is a muon neutrino.

    The detector originally picked up the event on June 11, 2014. The IceCube collaboration conducts a blind analysis of its data, which means that it looks at it in large batches, in this case collected over a couple of years.

    When they looked at their data, they sent an alert to scientists working on the HAWC Gamma-Ray Observatory, an array that collects gamma-ray data from a large range of the sky over time.

    HAWC High Altitude Cherenkov Experiment
    HAWC High Altitude Cherenkov Experiment

    Scientists have already looked through HAWC 2014 data for an associated gamma-ray signal, says gamma-ray scientist Werner Hofmann of the Max Planck Institute for Nuclear Physics in Germany.

    From here on out, Halzen says, the IceCube collaboration will send alerts to other experiments that study gamma rays as soon as possible after detecting an ultra-high-energy neutrino event.

    “We are now going to announce events in real time,” Halzen says. “We’re going to bring out events like this hopefully in minutes.”

    That way even telescopes like the VERITAS telescope or the Fermi Gamma-ray Space Telescope will be able to point in the right direction to try to find a signal. Halzen says he expects these “astronomical telegrams” to come about once per month.

    Additional reporting contributed by Ali Sundermier.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:57 pm on August 3, 2015 Permalink | Reply
    Tags: Astrophysical Multimessenger Observatory Network, , Neutrinos   

    From IceCube: “AMON, the Astrophysical Multimessenger Observatory Network” 

    icecube
    IceCube South Pole Neutrino Observatory

    31 Jul 2015
    Azadeh Keivani, Gordana Tesic and Doug Cowen

    1
    Map showing AMON connections with other collaborating observatories. Image: AMON

    The realization of multimessenger astrophysics will open up a new field of exploration of the most violent phenomena in the universe. Today, messenger particles of all four of nature’s fundamental forces reach detectors on the ground and satellites in space. Finding coincident signals from these experiments in real time will give us tremendous leverage in the hunt for their sources. The Astrophysical Multimessenger Observatory Network (AMON)* will link existing and future high-energy astrophysical observatories into a single virtual system, enabling near real-time coincidence searches for multimessenger astrophysical transients and their electromagnetic counterparts and providing alerts to follow-up observatories.

    AMON member observatories, those that have signed the AMON Memorandum of Understanding (MoU), include the IceCube and ANTARES neutrino observatories, the HAWC and VERITAS gamma-ray observatories, the Pierre Auger Cosmic Ray Observatory, the [NASA] Swift satellite, the FACT telescope, and the MASTER robotic telescope network. The Advanced LIGO gravitational wave detector, the Fermi LAT orbital telescope, and the Palomar Transient Factory have signed the AMON Letter of Collaboration (LoC), an intermediate step towards the MoU.

    Anteres Neutrino Telescope Underwater
    Anteres

    HAWC High Altitude Cherenkov Experiment
    HAWC

    Pierre Auger Observatory
    Pierre Auger Observatory

    NASA SWIFT Telescope
    NASA/Swift

    FACT Telescope
    FACT

    MIT Advanced Ligo
    Advanced Ligo

    NASA Fermi LAT
    NASA/Fermi LAT

    Caltech Palomar Transit Factory interior
    Caltech Palomar Transit Factory

    IceCube plays a key role in AMON multimessenger searches by providing high-quality neutrino data over a wide range of energies. There are two neutrino streams from IceCube that are transmitted to AMON in real time: the muon neutrino singlet stream and the high-energy starting event (HESE) stream.

    The muon neutrino singlet stream contains mostly data from atmospheric neutrino events. The data are distilled down to a few important quantities, such as direction, arrival time, and energy. These events, about 10 per hour, will first reach the IceCube main data center in Madison, through the standard satellite data transfer from the South Pole. Then, they will immediately be copied to AMON servers at Penn State. These events alone, which are dominated by neutrinos from cosmic-ray showers, cannot be used to make a statistically significant discovery of an astrophysical source. However, if one or more of these events are found in temporal and spatial coincidence with an event from another multimessenger data stream, together they could lead to the discovery of an otherwise hidden astrophysical source. If such coincidences are detected, AMON will distribute alerts in real time for follow-up observations via the Gamma-ray Coordinates Network (GCN).

    AMON also receives the HESE stream, which is IceCube’s most signal-rich data used in searches for astrophysical sources. But the stream also contains a significant amount of atmospheric high-energy neutrino events. After being transmitted to AMON, the “signal” events from the HESE stream, defined as those with energies above a certain threshold, will be sent immediately for follow-up observations via GCN. The remaining HESE events will be used in the standard AMON coincidence analyses.

    Additionally, there are ongoing efforts with other collaborators (e.g., from the Pierre Auger and HAWC collaborations) to get their subthreshold data streams in real time to AMON. The analyses performed so far include archival searches for jointly emitting neutrino + gamma-ray data (IC40/59 + Fermi LAT) and coincidence analysis of neutrino (IceCube), gamma-ray (HAWC), and cosmic-ray data (Pierre Auger), which aim to detect a distinctive primordial black hole (PBH) evaporation signature. The archival searches currently underway include coincidence analyses between Pierre Auger data and public IceCube data, Swift gamma-ray and public IceCube data, and Swift gamma-ray and public LIGO gravitational wave triggers. All these types of analyses are planned to be conducted in real time. Plans are also being considered to extend the neutrino + gamma-ray searches using private IceCube data (IC79/86 + Fermi LAT) in collaboration with IceCube members.

    2
    Gordana Tesic and Azadeh Keivani of Penn State in front of AMON computers. Image: AMON

    In May 2015, AMON established a connection with GCN**, an important milestone toward real-time alert distribution. Initially, AMON alert streams at GCN will be established as private streams, available only to collaborating AMON experiments. In the future, any of these streams can be made public with the approval of the participating observatories. For example, IceCube has decided to make HESE neutrinos public, so the AMON stream at GCN broadcasting the HESE alerts will be open for public as well.

    Currently, AMON is deploying two new high-availability (less than one hour of downtime per year) servers, which are physically and cybersecure and have memory mirroring and power redundancy. Each server is hosted in a separate secured data center on the Penn State campus. This system is administered by the Institute for CyberScience at Penn State. The new servers will be ready as early as September 2015 to start issuing real-time alerts via GCN to the AMON collaborators and follow-up facilities.

    ** Thanks to Scott Barthelmy, the principal investigator of GCN, who made this connection possible.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 462 other followers

%d bloggers like this: