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  • richardmitnick 1:25 pm on July 23, 2015 Permalink | Reply
    Tags: , Neutrinos, ,   

    From Symmetry: “A new first for T2K” 

    Symmetry

    July 23, 2015
    Kathryn Jepsen

    1
    Courtesy of Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

    The Japan-based neutrino experiment has seen its first three candidate electron antineutrinos

    Scientists on the T2K neutrino experiment in Japan announced today that they have spotted their first possible electron antineutrinos.

    When the T2K experiment first began taking data in January 2010, it studied a beam of neutrinos traveling 295 kilometers from the J-PARC facility in Tokai, on the east coast, to the Super-Kamiokande detector in Kamioka in western Japan. Neutrinos rarely interact with matter, so they can stream straight through the earth from source to detector.

    From May 2014 to June 2015, scientists used a different beamline configuration to produce predominantly the antimatter partners of neutrinos, antineutrinos. After scientists eliminated signals that could have come from other particles, three candidate electron antineutrino events remained.

    T2K scientists hope to determine if there is a difference in the behavior of neutrinos and antineutrinos.

    “That is the holy grail of neutrino physics,” says Chang Kee Jung of State University of New York at Stony Brook, who until recently served as international co-spokesperson for the experiment.

    If scientists caught neutrinos and their antiparticles acting differently, it could help explain how matter came to dominate over antimatter after the big bang. The big bang should have produced equal amounts of each, which would have annihilated one another completely, leaving nothing to form our universe. And yet, here we are; scientists are looking for a way to explain that.

    “In the current paradigm of particle physics, this is the best bet,” Jung says.

    Scientists have previously seen differences in the ways that other matter and antimatter particles behave, but the differences have never been enough to explain our universe. Whether neutrinos and antineutrinos act differently is still an open question.

    Neutrinos come in three types: electron neutrinos, muon neutrinos and tau neutrinos. As they travel, they morph from one type to another. T2K scientists want to know if there’s a difference between the oscillations of muon neutrinos and muon antineutrinos. A possible upgrade to the Super-Kamiokande detector could help with future data-taking.

    One other currently operating experiment can look for this matter-antimatter difference: the [FNAL] NOvA experiment, which studies a beam that originates at Fermilab near Chicago with a detector near the Canadian border in Minnesota.

    FNAL NOvA experiment
    FNAL NOvA

    “This result shows the principle of the experiment is going to work,” says Indiana University physicist Mark Messier, co-spokesperson for the NOvA experiment. “With more data, we will be on the path to answering the big questions.”

    It might take T2K and NOvA data combined to get scientists closer to the answer, Jung says, and it will likely take until the construction of the even larger DUNE neutrino experiment in South Dakota to get a final verdict.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:54 am on July 22, 2015 Permalink | Reply
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    From Symmetry: “Underground plans” 

    Symmetry

    July 22, 2015
    Liz Kruesi

    1
    Courtesy of Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

    The Super-Kamiokande collaboration has approved a project to improve the sensitivity of the Super-K neutrino detector.

    Super-Kamiokande, buried under about 1 kilometer of mountain rock in Kamioka, Japan, is one of the largest neutrino detectors on Earth. Its tank is full of 50,000 tons (about 13 million gallons) of ultrapure water, which it uses to search for signs of notoriously difficult-to-catch particles.

    Recently members of the Super-K collaboration gave the go-ahead to a plan to make the detector a thousand times more sensitive with the help of a chemical compound called gadolinium sulfate.

    Neutrinos are made in a variety of natural processes. They are also produced in nuclear reactors, and scientists can create beams of neutrinos in particle accelerators. These particles are electrically neutral, have little mass and interact only weakly with matter—characteristics that make them extremely difficult to detect even though trillions fly through any given detector each second.

    Super-K catches about 30 neutrinos that interact with the hydrogen and oxygen in the water molecules in its tank each day. It keeps its water ultrapure with a filtration system that removes bacteria, ions and gases.

    Scientists take extra precautions both to keep the ultrapure water clean and to avoid contact with the highly corrosive substance.

    “Somebody once dropped a hammer into the tank,” says experimentalist Mark Vagins of the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe. “It was chrome-plated to look nice and shiny. Eventually we found the chrome and not the hammer.”

    When a neutrino interacts in the Super-K detector, it creates other particles that travel through the water faster than the speed of light, creating a blue flash. The tank is lined with about 13,000 phototube detectors that can see the light.

    Looking for relic neutrinos

    On average, several massive stars explode as supernovae every second somewhere in the universe. If theory is correct, all supernovae to have exploded throughout the universe’s 13.8 billion years have thrown out trillions upon trillions of neutrinos. That means the cosmos would glow in a faint background of relic neutrinos—if scientists could just find a way to see even a fraction of those ghostlike particles.

    For about half of the year, the Super-K detector is used in the T2K experiment, which produces a beam of neutrinos in Tokai, Japan, some 183 miles (295 kilometers) away, and aims it at Super-K. During the trip to the detector, some of the neutrinos change from one type of neutrino to another. T2K studies that change, which could give scientists hints as to why our universe holds so much more matter than antimatter.

    But a T2K beam doesn’t run continuously during that half year. Instead, researchers send a beam pulse every few seconds, and each pulse lasts just a few microseconds long. Super-K still detects neutrinos from natural processes while scientists are running T2K.

    In 2002, at a neutrino meeting in Munich, Germany, experimentalist Vagins and theorist John Beacom of The Ohio State University began thinking of how they could better use Super-K to spy the universe’s relic supernova neutrinos.

    “For at least a few hours we were standing there in the Munich subway station somewhere deep underground, hatching our underground plans,” Beacom says.

    To pick out the few signals that come from neutrino events, you have to battle a constant clatter of background noise of other particles. Other incoming cosmic particles such as muons (the electron’s heavier cousin) or even electrons emitted from naturally occurring radioactive substances in rock can produce signals that look like the ones scientists hope to find from neutrinos. No one wants to claim a discovery that later turns out to be a signal from a nearby rock.

    Super-K already guards against some of this background noise by being buried underground. But some unwanted particles can get through, and so scientists need ways to separate the signals they want from deceiving background signals.

    Vagins and Beacom settled on an idea—and a name for the next stage of the experiment: Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super! (GADZOOKS!). They proposed to add 100 tons of the compound gadolinium sulfate—Gd2(SO4)3—to Super-K’s ultrapure water.

    When a neutrino interacts with a molecule, it releases a charged lepton (a muon, electron, tau or one of their antiparticles) along with a neutron. Neutrons are thousands of times more likely to interact with the gadolinium sulfate than with another water molecule. So when a neutrino traverses Super-K and interacts with a molecule, its muon, electron, or antiparticle (Super-K can’t see tau particles) will generate a first pulse of light, and the neutron will create a second pulse of light: “two pulses, like a knock-knock,” Beacom says.

    By contrast, a background muon or electron will make only one light pulse.

    To extract only the neutrino interactions, scientists will use GADZOOKS! to focus on the two-signal events and throw out the single-signal events, reducing the background noise considerably.

    The prototype

    But you can’t just add 100 tons of a chemical compound to a huge detector without doing some tests first. So Vagins and colleagues built a scaled-down version, which they called Evaluating Gadolinium’s Action on Detector Systems (EGADS). At 0.4 percent the size of Super-K, it uses 240 of the same phototubes and 200 tons (52,000 gallons) of ultrapure water.

    Over the past several years, Vagins’ team has worked extensively to show the benefits of their idea. One aspect of their efforts has been to build a filtration system that removes everything from the ultrapure water except for the gadolinium sulfate. They presented their results at a collaboration meeting in late June.

    On June 27, the Super-K team officially approved the proposal to add gadolinium sulfate but renamed the project SuperK-Gd. The next steps are to drain Super-K to check for leaks and fix them, replace any burned out phototubes, and then refill the tank.

    But this process must be coordinated with T2K, says Masayuki Nakahata, the Super-K collaboration spokesperson.

    Once the tank is refilled with ultrapure water, scientists will add in the 100 tons of gadolinium sulfate. Once the compound is added, the current filtration system could remove it any time researchers would like, Vagins says.

    “But I believe that once we get this into Super-K and we see the power of it, it’s going to become indispensable,” he says. “It’s going to be the kind of thing that people wouldn’t want to give up the extra physics once they’re used to it.”

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 12:57 pm on July 21, 2015 Permalink | Reply
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    From FNAL: “DUNE and LBNF on the move” 

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

    July 21, 2015
    1
    Joe Lykken

    Last week a distinguished committee of 24 experts conducted a comprehensive Critical Decision 1 review of the DUNE and LBNF projects for the Department of Energy. Steve Meador, head of the Office of Project Assessment for the DOE Office of Science, chaired the review, with Jim Siegrist and Mike Procario of the Office of High Energy Physics observing.

    FNAL DUNE
    DUNE

    FNAL LBNF
    LBNF

    Fermilab has participated in quite a few critical decision reviews in the year since the P5 report, “Building for Discovery,” set the course for U.S. particle physics. But last week’s event was not “just another review.” DUNE, combined with LBNF, is the largest new initiative at Fermilab since the Tevatron and would be the first truly international megascience project ever hosted in the United States. In short, this review was a really, really big deal.

    The project teams were led by Elaine McCluskey, LBNF project manager, and Eric James, DUNE technical coordinator, along with DUNE spokespeople André Rubbia and Mark Thomson and DUNE resource coordinator Chang Kee Jung. Also on hand were Sergio Bertolucci and Marzio Nessi of CERN, and leadership of the former LBNO and LBNE collaborations, including Dario Autiero and Jim Strait. The new LBNF far-site project manager, Mike Headley, led a contingent from the South Dakota Science and Technology Authority.

    Reviewers for DOE critical decisions are not selected for their propensity to be nice. On the final day closeout, even the most experienced project team perches on their seats in trepidation, expecting to have their ears boxed. Thursday’s closeout for DUNE and LBNF was a dense hour of findings, comments, and recommendations, but the tone was highly positive. Here are a few quotes from the closeout slides:

    DUNE: “The DUNE collaboration is growing and well engaged and led by a strong, well-organized management team. An impressive CDR document has been produced.”

    Beamline: “The beamline design team is highly qualified and was well prepared. Many have worked on the previous neutrino beamlines and bring that world-leading experience to the table.”

    Far-site conventional facilities: Strong team with an in-depth knowledge of the site and facilities.

    Cost and schedule: “All DOE and non-DOE scope is included in the preliminary baseline and is consistent with LHC (CERN) costing practices … The committee found the preliminary baseline to be complete and comprehensive. In some areas, maturity is beyond CD-1.”

    Management: “Very (very) strong management team members in place on both projects.”

    The next morning, Friday at 7:45 a.m., the “very (very) strong management team” assembled for their daily meeting with Pepin Carolan, the DOE federal project director for DUNE/LBNF. Time for a few minutes of relaxed self-congratulation? Absolutely not — instead a laser-like focus on the path to the next major hurdle: a CD3a review later this year enabling a construction start for the far-site facilities.

    A strong week for the future of neutrino science.

    See the full article here.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. 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 11:51 am on July 17, 2015 Permalink | Reply
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    From FNAL- “Frontier Science Result: MINERvA Neutrinos in nuclei: studying group effects of interactions” 

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

    July 17, 2015

    1
    Joel Mousseau, University of Florida

    These results were presented by the author at a recent Joint Experimental-Theoretical Physics Seminar. Mousseau’s presentation is available online.

    2
    This plot shows the ratio for iron (top) and lead (bottom) for neutrino deep inelastic scattering cross sections versus the fractional momentum of the struck quarks (Bjorken-x) for MINERvA data (black points) and the prediction (red line).

    Physics is a holistic science in which we consider not only the individual parts but also how these parts combine into groups. Nucleons, or protons and neutrons, combine in groups to form atomic nuclei. The differences between how free nucleons behave and how nucleons inside a nucleus (bound nucleons) behave are called nuclear effects.

    In the past, scientists have measured nuclear effects using beams of high-energy electrons. These high-energy beams allow electrons to interact with the quarks contained inside nucleons and nuclei, an interaction called deep inelastic scattering, or DIS. Scientists can now also bombard nuclei with neutrinos, which can also induce deep inelastic scattering. Studying these interactions can help us understand the behavior of quarks.

    Using a beam of neutrinos, MINERvA has performed the first neutrino DIS analysis in the energy range of 5 to 50 GeV.

    FNAL MINERvA
    MINERvA

    Neutrinos and electrons interact with quarks within the nucleus differently; we do not expect nuclear effects in neutrino DIS will be the same as electron DIS.

    MINERvA observes DIS interactions by measuring the cross section, or probability, of a neutrino interacting with quarks inside bound nucleons as a function of a property called Bjorken-x. Bjorken-x is proportional to the momentum of the quark that was stuck inside the nucleon.

    MINERvA took data on neutrino interactions with carbon, iron and lead nuclei. We compared these data to a theoretical model that assumes the nuclear effects for both neutrino and electron interactions are the same.

    We found that the data did not agree with the assumption in the lowest Bjorken-x values (0.1 to 0.2 — see figures) for lead. Further, the cross section for lead at those values differs significantly from those for carbon or iron. We say that the nuclear effect is enhanced in that region for lead.

    This enhancement was seen in a previous MINERvA inclusive analysis that considered all kinds of interactions together — without singling out deep inelastic scattering.

    In contrast, the model in the largest Bjorken-x range (0.4 to 0.75) agrees very well with data. This is intriguing, since the cause of nuclear effects in this region is not well understood. Whatever underlying physics governs behavior in this region, it appears to be the same for neutrinos and electrons.

    This information is very valuable in building new models of this mysterious effect. Understanding these effects are a priority for MINERvA and will be studied more extensively using data we are currently collecting, taken at higher energies and higher statistics. This data will be invaluable in resolving the theoretical puzzles at large and small Bjorken-x.

    See the full article here.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. 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 9:24 am on July 16, 2015 Permalink | Reply
    Tags: , , , Neutrinos   

    From IceCube: “A combined analysis of the astrophysical neutrino flux in IceCube” 

    icecube
    IceCube South Pole Neutrino Observatory

    16 Jul 2015
    Sílvia Bravo

    Since the first detection of neutrinos with PeV energies, IceCube researchers have performed several follow-up studies to investigate the nature of the astrophysical neutrino flux. These analyses have revealed, for instance, that this flux extends down to energies around 25 TeV and that it displays different event topologies.

    The IceCube Collaboration is now revisiting these results in a combined analysis accepted for publication in The Astrophysical Journal. The analysis is based on the results of six individual studies and uses up to three observables—energy, zenith angle and event topology—to derive improved constraints on the energy spectrum and the composition of neutrino flavors (νe , νμ , ντ) of the astrophysical neutrino flux.

    The current study shows that the energy spectrum of the astrophysical neutrino flux is well described by a power law with a best-fit spectral index of -2.50 ± 0.09, for energies between 25 TeV and 2.8 PeV. A continuous power-law spectrum with index -2, which is a popular benchmark model, is excluded with a significance of 3.8 sigma.

    1
    Energy spectrum of the astrophysical neutrino flux derived in the combined analysis (red shaded area). The blue shaded area shows the flux of neutrinos created in the decay of pions and kaons in the atmosphere; the green line is an upper limit on the flux of so-called prompt atmospheric neutrinos from the decay of charmed mesons. Image: IceCube Collaboration.

    The combined analysis benefits from an increased size of the event sample, which is also more diverse—including track-like as well as shower-like events. Tracks are produced by most interactions of muon neutrinos, in which long-range muons are produced. On the other hand, interactions of electron and tau neutrinos, as well as some muon neutrinos, give rise to shower-like events.

    “With this study, we are able to present the first comprehensive characterization of the astrophysical neutrino flux at IceCube,” explains Lars Mohrmann, an IceCube researcher at DESY in Zeuthen and corresponding author of the paper.

    The flavor composition of the astrophysical neutrino flux brings us information about the production mechanism and the properties of the neutrino sources. In many scenarios, neutrinos are produced in the decay of pions, which create one electron neutrino per every two muon neutrinos and no tau neutrinos (νe : νμ : ντ =1:2:0). Because neutrinos switch flavors during their long journey through the universe, the 3-flavor composition at Earth is expected to be approximately even (≈1:1:1). The constraints on the flavor composition derived with this study show that the data are compatible with this scenario as well as with the sole production of muon neutrinos (0:1:0).

    In another mechanism, astrophysical neutrinos are produced in the decay of neutrons whereby only electron neutrinos are produced (1:0:0). However, this scenario is excluded with a significance of 3.6 sigma.

    2
    Constraints on the flavor composition of the astrophysical neutrino flux. Each of the three axes displays the fraction of a particular neutrino flavor with respect to the total flux. The best-fit composition is marked with X. Image: IceCube Collaboration.

    These results illustrate that we can learn something about the sources of the astrophysical neutrinos, even though we have not identified them yet,” continues Mohrmann. “It will be important to continue investigating the energy spectrum and the flavor composition with more data in the future.”

    + Info: “A combined maximum-likelihood analysis of the high-energy astrophysical neutrino flux measured with IceCube,” IceCube Collaboration: M. G. Aartsen et al. Accepted by The Astrophysical Journal, arxiv.org/abs/1507.03991

    See the full article here.

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

     
  • richardmitnick 8:42 am on July 9, 2015 Permalink | Reply
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    From FNAL: “Fermilab’s flagship accelerator sets world record” 

    FNAL Home

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

    July 8, 2015
    Media contact:
    Andre Salles, Fermilab Office of Communication, 630-840-3351, media@fnal.gov

    Science contact:
    Ioanis Kourbanis, Fermilab Accelerator Division, 630-840-4423, ioanis@fnal.gov

    Most powerful high-energy particle beam for a neutrino experiment ever generated

    FNAL Main Injector Accelerator

    A key element in a particle-accelerator-based neutrino experiment is the power of the beam that gives birth to neutrinos: The more particles you can pack into that beam, the better your chance to see neutrinos interact in your detector. Today scientists announced that Fermilab has set a world record for the most powerful high-energy particle beam for neutrino experiments.

    Scientists, engineers and technicians at the U.S. Department of Energy’s Fermi National Accelerator Laboratory have achieved for high-energy neutrino experiments a world record: a sustained 521-kilowatt beam generated by the Main Injector particle accelerator. More than 1,000 physicists from around the world will use this high-intensity beam to more closely study neutrinos and fleeting particles called muons, both fundamental building blocks of our universe.

    The record beam power surpasses that of the 400-plus-kilowatt beam sent to neutrino experiments from particle accelerators at CERN.

    Setting this world record is an initial step for the Fermilab accelerator complex as it will gradually increase beam power over the coming years. The next goal for the laboratory’s two-mile-around Main Injector accelerator — the final and most powerful in Fermilab’s accelerator chain — is to deliver 700-kilowatt beams to the laboratory’s various experiments. Ultimately, Fermilab plans to make additional upgrades to its accelerator complex over the next decade, achieving beam power in excess of 1,000 kilowatts, also referred to as 1 megawatt.

    “We have the world’s highest-power beam for neutrinos, and we’re only going up from here,” said Ioanis Kourbanis, head of the Main Injector Department at Fermilab.

    Laboratory-made neutrino experiments start by accelerating a beam of particles, typically protons, and then smashing them into a target to create neutrinos. Scientists then use particle detectors to “catch” as many of those neutrinos as possible and record their interactions. Neutrinos rarely engage with matter: Only one out of every trillion emerging from the proton beam will interact in an experiment’s detector. The more particles in that beam, the more opportunities researchers will have to study these rare interactions.

    The amped-up particle beam provided by the Main Injector enriches the lab’s neutrino supply, positioning Fermilab to become the primary laboratory for accelerator-based neutrino research. Neutrinos are also made in stars and in the Earth’s core, and they pass through everything — people and planets alike.

    “The idea is that if you build a more intense beam, neutrino scientists from around the world will beat a path to your door,” said Fermilab Deputy Director Joe Lykken. “This is exactly what’s happening.”

    Fermilab currently operates four neutrino experiments: MicroBooNE, MINERvA, MINOS+ and the laboratory’s largest-to-date neutrino experiment, NOvA, which sends particles from Fermilab’s suburban Chicago location to a far detector 500 miles away in Ash River, Minnesota. The laboratory is working with scientists from around the world on expanding its short-baseline neutrino program and would also serve as host to the proposed flagship Long-Baseline Neutrino Facility and Deep Underground Neutrino Experiment, or DUNE. Scientists aim to address basic questions about the mass and properties of each kind of neutrino as well as the role neutrinos played in the evolution of the universe.

    “Reaching this milestone is a fantastic achievement for Fermilab; beam power is everything in our field,” said DUNE co-spokesperson Mark Thomson of the University of Cambridge. “The ability for Fermilab to deliver, yet again, gives the international neutrino community huge confidence in the future U.S.-hosted neutrino program.”

    Fermilab is also preparing to operate two experiments for studying muons, short-lived particles that could reveal secrets about the earliest moments of the universe. The increased beam power will also benefit the Fermilab Test Beam Facility, one of the few facilities in the world that provides muons, pions and other particles that researchers can use to test their particle detectors.

    Since 2011, Fermilab has made significant upgrades to its accelerators and reconfigured the complex to provide the best possible particle beams for neutrino and muon experiments. With the dedicated work of the Fermilab Accelerator Division, the Main Injector is on track to nearly double its Tevatron-era beam power by 2016.

    “Fermilab’s beamline has been a tremendous driver of neutrino science for many years, and the continued improvements to the intensity mean that it will remain a driver for many years to come,” said Indiana University’s Mark Messier, co-spokesperson for the NOvA experiment.

    See the full article here.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. 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 11:19 am on July 3, 2015 Permalink | Reply
    Tags: , Neutrinos,   

    From Symmetry: “How do you solve a puzzle like neutrinos?” 

    Symmetry

    June 30, 2015
    Lauren Biron

    When it comes to studying particles that zip through matter as though it weren’t even there, you use every method you can think of.

    1
    Artwork by Sandbox Studio, Chicago with Ana Kova

    Sam Zeller sounds borderline embarrassed by scientists’ lack of understanding of neutrinos—particularly how much mass they have.

    “I think it’s a pretty sad thing that we don’t know,” she says. “We know the masses of all the particles except for neutrinos.” And that’s true even for the Higgs, which scientists only discovered in 2012.

    Ghostly neutrinos, staggeringly abundant and ridiculously aloof, have held onto their secrets long past when they were theorized in the 1930s and detected in the 1950s. Scientists have learned a few things about them:

    They come in three flavors associated with three other fundamental particles (the electron, muon and tau).
    They change, or oscillate, from one type to another.
    They rarely interact with anything, and trillions upon trillions stream through us every minute.
    They have a very small mass.

    But right now, there are still more questions than answers.

    Zeller, one of thousands of neutrino researchers around the world and co-spokesperson for the neutrino experiment MicroBooNE based at Fermilab, says the questions about neutrinos don’t stop at mass.

    FNAL MicroBooNE
    MicroBooNE

    She writes down a shopping list of things physicists want to find out:

    Is one type of neutrino much heavier than the other two, or much lighter?
    What is the absolute mass of the neutrino?
    Are there more than three types of neutrinos?
    Do neutrinos and antineutrinos behave differently?
    Is the neutrino its own antiparticle?
    Is our picture of neutrinos correct?

    No single experiment can answer all of these questions. Instead, there are dozens of experiments looking at neutrinos from different sources, each contributing a piece to the puzzle. Some neutrinos stream unimpeded from far away, born in supernovae, the sun, the atmosphere or cosmic sources. Others originate closer to home, in the Earth, nuclear reactors, radioactive decays or particle accelerators. Their different birthplaces imbue them with different flavors and energies—a range so great, it spans at least 16 orders of magnitude. Armed with the knowledge of where and how to look, scientists are entering an exhilarating experimental time.

    “That’s why neutrino physics is so exciting right now,” Zeller says. “It’s not as if we’re shooting in the dark or we don’t know what we’re doing. Worldwide, we’re embarking on a program to answer these questions. That path will make use of these many different sources, and in the end you put it all together and hope the story makes sense.”

    2

    Neutrinos from nuclear reactors

    The first confirmation that neutrinos were more than just a theory came from nuclear reactors, where neutrinos are produced in a process called beta decay. A team of scientists led by Clyde Cowan and Frederick Reines found neutrinos spewing in a steady stream from reactors at the Hanford Site in Washington and the Savannah River Plant in South Carolina between 1953 and 1959.

    Reactors have been useful for neutrino physics ever since, particularly because they produce only one kind of neutrino: electron antineutrinos. When studying the way particles change from one type to another, it’s invaluable to know exactly what you’re starting with.

    Reactor experiments such as KamLAND, which studied particles from 53 nuclear reactors in Japan, echoed results from projects examining solar and atmospheric neutrinos. All of them found that neutrinos changed flavor over time.

    KamLAND
    KamLAND

    “Once we know that neutrinos are oscillating, that gives us the strongest evidence that neutrinos are massive,” says Dan Dwyer, a scientist at Lawrence Berkeley National Laboratory and researcher on the international Daya Bay Reactor Neutrino Experiment based in China.

    Daya Bay
    Daya Bay

    Such projects now look for the way neutrinos change and for hints about their relative masses.

    Because reactor experiments allow for precision, they’re also ideal to hunt for a fourth type of particle—the yet unobserved sterile neutrino, thought to interact only through gravity.

    3

    Neutrinos from accelerators

    Reactor neutrinos aren’t the only way to look for additional neutrinos. That’s where the powerhouse of neutrino research—the accelerator—comes in.

    Scientists can use a beam of easier-to-control particles such as protons to create a beam of neutrinos.

    First, they accelerate the protons and smash them into a target. The energy released in this collision converts to mass in the form of a flood of new massive particles. Those particles decay into less massive particles, including neutrinos.

    Before the massive particles decay, scientists use magnets to focus them into a beam. Afterward, they use blocking material to skim off unwanted bits while the neutrinos—which can pass through a light-year of lead without even noticing it’s there—flow freely through.

    Neutrino beams from accelerators are typically made of muon neutrinos and antineutrinos, but the experiments that use accelerators split into two main groups: short-baseline experiments, which look at oscillations over smaller distances, and long-baseline experiments, which study neutrinos that have traveled over hundreds of miles.

    Both types of experiments look at how neutrinos oscillate. At short distances, neutrinos are less likely to have changed flavors, though the influence of undiscovered new particles or forces might affect that rate. At long distances, neutrinos are more likely to have changed after traveling for a few milliseconds at nearly the speed of light. Oscillation patterns can give scientists clues as to the masses of the different types of neutrinos.

    Oscillation studies over long distances, like Japan’s T2K experiment or the United States’ NOvA experiment and proposed DUNE experiment, can help researchers find how neutrinos relate to antineutrinos. One method is to search for charge parity violation.

    T2K
    T2K

    FNAL DUNE
    DUNE

    This complicated-sounding term essentially asks whether matter and antimatter can pull off “the old switcheroo”—that is, whether the universe treats matter and antimatter particles identically. If the oscillations of neutrinos are fundamentally different from the oscillations of antineutrinos, then CP is broken.

    Scientists already know that CP is violated for one major building block of the universe: the quarks. Does the same happen for the other major family, the leptons? Neutrinos might hold the key.

    4

    Studying neutrinos without neutrinos

    It’s odd that one of the most important questions regarding neutrinos can be answered only by looking for a process apparently lacking in neutrinos.

    In neutrinoless double beta decay, a particle would decay into electrons and neutrinos, but the neutrinos would annihilate one another within the nucleus.

    “If you see it, it tells you that neutrinos are different in a fundamental way,” says Boris Kayser, a theorist at Fermilab.

    Neutrinoless double beta decay would occur only if neutrinos and their antiparticles were one and the same. No other fundamental particle of matter has this property.

    “Neutrinos are very special,” Kayser says. “It could be that they violate rules that other particles don’t violate.”

    Several experiments worldwide are under way to search for this process, with future generations planned.

    A different experiment, KATRIN, hopes to find the masses of the neutrinos by looking at particular electrons. As a radioactive kind of hydrogen decays, it spits out an antineutrino and a partner electron. Scientists will use the world’s largest spectrometer to measure the energy of these electrons to learn about the neutrino.

    KATRIN Experiment
    KATRIN

    6

    Geoneutrinos

    Unperturbed by magnetism or mass in their paths, neutrinos are perhaps the ultimate messengers of the universe. Once found, the particles point back to their origins, places scientists can’t otherwise see. Investigating these neutrinos provides insight into the particles themselves and is a useful way to probe the unknown.

    Take the Earth as an example. Scientists can use detectors to capture geoneutrinos, typically low-energy electron antineutrinos, to learn about the composition of our planet without trying to drill miles below the surface. Because we’ve learned that neutrinos are born of particle decay, the number of geoneutrinos tells researchers how much potassium, thorium and uranium lurk below, heating our world.

    7

    Solar neutrinos

    Neutrinos are also created in processes in the sun. But when Ray Davis built a solar neutrino detector filled with dry cleaning fluid, his experiment picked up only a third of the predicted neutrinos.

    This solar neutrino problem hinted that we didn’t understand our sun; in reality, we didn’t understand neutrinos. Solar neutrino experiments after Davis’ showed that neutrinos from the sun were changing flavor, and a reactor experiment later confirmed that the flavor change was caused by neutrino oscillation.

    Modern solar neutrino experiments such as Italy’s Borexino provide insight into the core of the sun and help put limits on sterile neutrinos.

    Others, like Japan’s Super-Kamiokande detector, can look at how solar neutrinos change when traveling through the earth versus neutrinos oscillating primarily in the vacuum of space.

    Super-Kamiokande experiment Japan
    Super-Kamiokande

    “The reason that’s important is that if the neutrino interacts with matter in new, unknown ways, which is possible, then this effect would be changed,” says Josh Klein, professor of physics at the University of Pennsylvania. “It’s a very sensitive measure of new physics.”

    8

    Cosmic neutrinos

    Cosmic neutrinos illuminate powerful phenomena occurring within our galaxy and beyond. Massive extragalactic neutrino hunting experiments, such as the IceCube experiment that sprawls across a cubic kilometer of ice in Antarctica, can find neutrinos that have oscillated over much longer distances than we can test with accelerators.

    ICECUBE neutrino detector
    IceCube neutrino detector interior
    IceCube

    “We see neutrinos [with energies] from below 10 [billion electronvolts] to above a thousand [trillion electronvolts],” says Francis Halzen, physicist at the University of Wisconsin, Madison, and leader of IceCube. “Nobody has ever built something that covers this energy range of particles.”

    Giant neutrino detectors like this one can look for sterile neutrinos and gather information on oscillations and mass hierarchy.

    They’re also useful for understanding dark matter and supernovae, analyzing atmospheric neutrinos that form when cosmic rays hit our atmosphere and telling other astronomers where to point their telescopes if neutrinos from a supernova burst hit. Physicists learn properties of neutrinos, but the neutrinos in turn unlock secrets of the universe.

    “Whenever we have made a picture of the universe in a different wavelength region of light, we have always seen things we didn’t expect,” Halzen says. “We’re doing now what astronomers have been doing for decades: looking at the sky in different ways.”

    Neutrinos matter for matter

    At the end of the day, why go to all this trouble for such a tiny particle? In addition to helping scientists probe the interior of the Earth or the far-off corners of the cosmos, neutrinos could hold the key to why matter exists today.

    Scientists know that antimatter and matter are produced in equal parts and should ultimately have annihilated one another, leaving a dark and empty universe. But here we stand, matter in all its glory.

    Sometime early in the universe’s history, an imbalance arose and shifted the scales toward a matter-dominated universe. If physicists find that neutrinos have certain characteristics—including CP violation—it could help explain why the universe turned out the way it did.

    “They’re the most abundant massive particle in the universe,” Zeller says. “If you find out something weird about neutrinos, it’s bound to tell you something about how the universe evolved or how it came to be the way we observe today.”

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 7:42 am on June 10, 2015 Permalink | Reply
    Tags: , Hyper-K, Neutrinos,   

    From Symmetry: “Japan’s next big neutrino project” 

    Symmetry

    June 09, 2015
    Glenn Roberts Jr.

    1
    Artwork by Sandbox Studio, Chicago

    The proposed Hyper-K experiment would dwarf its predecessor.

    In 1998, the Super-K detector in Japan revealed that ubiquitous, almost massless particles called neutrinos have the ability to morph from one type to another. That landmark finding has become one of the most heavily cited scientific results in particle physics.

    Super-Kamiokande experiment Japan
    Super-K

    Now scientists have proposed to build a successor to the still-operating Super-K: Hyper-K, a detector with an active volume 25 times its size.

    Part microscope and part telescope, the proposed Hyper-K experiment could fill in some of the blanks in our understanding of our universe. It could help explain why the universe favors matter over antimatter. It could provide new details about the fluctuating “flavors” or types of neutrinos. It could help elucidate whether there is any difference between neutrinos and their anti-particles.

    It could also provide a better understanding of dark matter and exploding stars and could reveal whether protons—a main ingredient in all atoms—have an expiration date.

    The proposed experiment would be complementary to DUNE, a planned long-baseline neutrino experiment in the United States that will use different technology.

    FNAL DUNE
    FNAL DUNE

    The “K” in Super-K and Hyper-K stands for a play on the word Kamioka, the name of a mountainous area about 200 miles west of Tokyo that houses multiple particle physics experiments.

    “The uniqueness of Hyper-K is its size and resolution,” says Tsuyoshi Nakaya of Kyoto University, who leads the Hyper-K steering committee and has been a part of Super-K since 1999.

    The central component in the Hyper-K project would be a massive cylindrical tank measuring about 248 meters long and 54 meters high, filled with 1.1 million tons of highly purified water. An alternate Hyper-K design calls for an egg-shaped tank.

    2
    Courtesy of: © Hyper-Kamiokande Collaboration

    Hyper-K would consist of an array of photo-detectors that would measure flashes of light produced in particle events and processes occurring in the tank. The mountain above Hyper-K would help to shield the detectors from the “noise” of other particles such as cosmic rays.

    Hyper-K would study a beam of neutrinos produced at the Japan Proton Accelerator Research Complex about 180 miles away in Tokai, and it would be able to detect neutrinos produced even farther away in Earth’s atmosphere and beyond. Hyper-K could also detect particles produced in the decay of a proton, something scientists have yet to see.

    “The discovery of proton decays would be revolutionary,” says Masato Shiozawa, Hyper-K project leader who works at the Institute for Cosmic Ray Research in Japan.

    Hyper-K has already won international support from institutions in 13 countries, with the largest groups coming from Japan, the United Kingdom, the United States, Switzerland and Canada. In January the ICCR announced a cooperative agreement to pursue Hyper-K with the Institute of Particle and Nuclear Studies in Japan’s High Energy Accelerator Research Organization.

    About 200 researchers are already working on the design of Hyper-K, and the collaboration is still welcoming new members. They hope to begin construction in 2018.

    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 7:15 pm on May 19, 2015 Permalink | Reply
    Tags: , Neutrinos,   

    From Symmetry: “Looking to the heavens for neutrino masses” 

    Symmetry

    May 19, 2015
    Matthew R. Francis

    1
    Artwork by Sandbox Studio, Chicago

    Neutrinos may be the lightest of all the particles with mass, weighing in at a tiny fraction of the mass of an electron. And yet, because they are so abundant, they played a significant role in the evolution and growth of the biggest things in the universe: galaxy clusters, made up of hundreds or thousands of galaxies bound together by mutual gravity.

    Thanks to this deep connection, scientists are using these giants to study the tiny particles that helped form them. In doing so, they may find out more about the fundamental forces that govern the universe.

    Curiously light

    When neutrinos were first discovered, scientists didn’t know right away if they had any mass. They thought they might be like photons, which carry energy but are intrinsically weightless.

    But then they discovered that neutrinos came in three different types [flavors] and that they can switch from one type to another, something only particles with mass could do.

    Scientists know that the masses of neutrinos are extremely light, so light that they wonder whether they come from a source other than the Higgs field, which gives mass to the other fundamental particles we know. But scientists have yet to pin down the exact size of these masses.

    It’s hard to measure the mass of such a tiny particle with precision.

    In fact, it’s hard to measure anything about neutrinos. They are electrically neutral, so they are immune to the effects of magnetic fields and related methods physicists use to detect particles. They barely interact with other particles at all: Only a more-or-less direct hit with an atomic nucleus can stop a neutrino, and that doesn’t happen often.

    Roughly a trillion neutrinos pass through your body each second from the sun alone, and almost none of those end up striking any of your atoms. Even the densest matter is nearly transparent to neutrinos. However, by creating beams of neutrinos and by building large, sensitive targets to catch neutrinos from nuclear reactors and the sun, scientists have been able to detect a small portion of the particles as they pass through.

    In experiments so far, scientists have estimated that the total mass of the three types of neutrinos together is roughly between 0.06 electronvolts and 0.2 electronvolts. For comparison, an electron’s mass is 511 thousand electronvolts and a proton weighs in at 938 million electronvolts.

    Because the Standard Model—the theory describing particles and the interactions governing them—predicts massless neutrinos, finding the exact neutrino mass value will help physicists modify their models, yielding new insights into the fundamental forces of nature.

    2
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    Studying galaxy clusters could provide a more precise answer.

    Footprints of a neutrino

    One way to study galaxy clusters is to measure the cosmic microwave background [CMB], the light traveling to us from 380,000 years after the big bang.

    Cosmic Background Radiation Planck
    CMB per ESA Planck

    ESA Planck
    ESA/Planck

    During its 13.8-billion-year journey, this light passed through and near all the galaxies and galaxy clusters that formed. For the most part, these obstacles didn’t have a big effect, but taken cumulatively, they filtered the CMB light in a unique way, given the galaxies’ number, size and distribution.

    The filtering affected the polarization—the orientation of the electric part of light—and originated in the gravitational field of galaxies. As CMB light traveled through the gravitational field, its path curved and its polarization twisted very slightly, an effect known as gravitational lensing. (This is a less dramatic version of lensing familiar from the beautiful Hubble Space Telescope images.)

    NASA Hubble Telescope
    NASA/ESA Hubble

    The effect is similar to the one that got everyone excited in 2014, when researchers with the BICEP2 telescope announced they had measured the polarization of CMB light due to primordial gravitational waves, which subsequent study showed to be more ambiguous.

    BICEP 2BICEP 2 interior
    BICEP

    That ambiguity won’t be a problem here, says Oxford University cosmologist Erminia Calabrese, who studies the CMB on the Atacama Cosmology Telescope [ACT] Polarization project.

    Princeton Atacama Technology Telescope
    ACT

    “There is one pattern of CMB polarization that is generated only by the deflection of the CMB radiation.” That means we won’t easily mistake gravitational lensing for anything else.

    Small and mighty

    Manoj Kaplinghat, a physicist at the University of California at Irvine, was one of the first to work out how neutrino mass could be estimated from CMB data alone. Neutrinos move very quickly relative to stuff like atoms and the invisible dark matter that binds galaxies together. That means they don’t clump up like other forms of matter, but their small mass still contributes to the gravitational field.

    Enough neutrinos, even fairly low-mass ones, can deprive a newborn galaxy of a noticeable amount of mass as they stream away, possibly throttling the growth of galaxies that can form in the early universe. It’s nearly as simple as that: Heavier neutrinos mean galaxies must grow more slowly, while lighter neutrinos mean faster galaxy growth.

    Kaplinghat and colleagues realized the polarization of the CMB provides a measure the total amount of gravity from galaxies in the form of gravitational lensing, which working backward will constrain the mass of neutrinos. “When you put all that together, what you realize is you can do a lot of cool neutrino physics,” he says.

    Of course the CMB doesn’t provide a direct measurement of the neutrino mass. From the point of view of cosmology, the three types of neutrinos are indistinguishable. As a result, what CMB polarization gives us is the total mass of all three types together.

    However, other projects are working on the other end of this puzzle. Experiments such as the Main Injector Neutrino Oscillation Search, managed by Fermilab, have determined the differences in mass between the different neutrino types.

    Depending on which neutrino is heaviest, we know how the masses of the other two types of neutrinos relate. If we can figure out the total mass, we can figure out the masses of each one. Together, cosmological and terrestrial measurements will get us the individual neutrino masses that neither is able to alone.

    The space-based Planck observatory and POLARBEAR project in northern Chile have yielded preliminary results in this search already.

    POLARBEAR McGill Telescope
    POLARBEAR telescope

    And scientists at ACTPol, located at high elevation in Chile’s Atacama Desert, are working on this as well. They will determine the neutrino mass as well as the best estimates we have, down to the lowest possible values allowed, once the experiments are running at their highest precision, Calabrese says.

    Progress is necessarily slow: The gravitational lensing pattern comes from seeing small patterns emerging from light captured across a large swath of the sky, much like the image in an Impressionist painting arises from abstract brushstrokes that look like very little by themselves.

    In more scientific terms, it’s a cumulative, statistical effect, and the more data we have, the better chance we have to measure the lensing effect—and the mass of a neutrino.

    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 10:59 am on May 7, 2015 Permalink | Reply
    Tags: , , Neutrinos,   

    From Sanford via KDLT: “Unlocking Mysteries of Dark Matter & Neutrinos in South Dakota” 

    Sanford Underground Research facility

    Sanford Underground levels

    Sanford Underground Research facility

    3
    KDLT

    May 06, 2015
    Tom Hanson, KDLT News Anchor

    The former Homestake Gold Mine in Lead closed in 2002. It is now the Sanford Underground Research Facility Funded by the state of South Dakota, the U.S. Department of Energy and a donation from T. Denny Sanford the lab is drawing some of the sharpest minds in science to South Dakota.

    The search for dark matter and the study of neutrinos are at the heart of two of the underground labs biggest projects. The equipment used in this research is so sensitive it has to be shielded from cosmic rays on the earth’s surface.

    Located almost a mile underground the LUX is a dark matter detector.

    Lux Dark Matter 2
    LUX Dark matter
    LUX

    2
    The two men behind the project Simon Fiorucci (left) and Harry Nelson are hunting something so rare, no one has ever seen it, in fact no one really knows exactly what it is.

    “We are trying to detect a new form of matter which we are absolutely sure constitutes about 85 percent of the matter in the universe,” said Nelson. “And the fabulous thing is no one knows what it is. So there are a bunch of conjectures and so the gadget behind us is dedicated to the most popular conjecture of what this dark matter of the universe is.”

    The gadget is the Large Underground Xenon Detector or LUX, a phone booth sized container holding liquid xenon, cooled to -160 degrees F and surrounded by thousands of gallons of specially treated water. And according to Sanford Underground Lab officials the LUX has the reputation as the most sensitive detector ever built. Nelson has a nack for taking a very complicated process and simplifying it.

    “Our detector occasionally should see a little touch of the dark matter and it will make the atoms in our detector recoil and emit a little bit of light and also make a little bit of electric charge, that’s what we are trying to do here,” said Nelson.

    But according to Fiorucci so far that hasn’t happened.

    “We’ve seen nothing at all, which at first glance you might think well that’s not great, actually what that means is we’ve eliminated quite a number of possibilities, said Fiorucci.

    4

    Possibilities surround the other big project currently underway at the Sanford lab. The Majorana Demonstrator is looking at neutrinos.

    Majorano Demonstrator Experiment
    Majorano

    Particles so small there are billions of them passing through your body as you read this story. Professor John Wilkerson and his team are searching for a rare form of radioactive decay.

    “If we see this rare decay it would actually tell us that neutrinos can be their own anti particle and it might explain why we exist, why there’s so much matter and why there’s not anti-matter in the universe,” said Wilkerson.

    The vast majority of the observable universe from our planet seems to be made of matter and not antimatter. Why? Is one of the most interesting questions facing scientists.

    Building on the success of the LUX and Majorana Demonstrator, the next generations of projects are coming to the underground facility.
    The LZ project will continue the search for dark matter and will be 30 times larger than the LUX.

    LZ project
    LZ Project

    However the Deep Underground Neutrino Experiment or DUNE will be the biggest of all.

    FNAL DUNE
    DUNE

    The $1.5 billion project will try to find out how neutrinos change from point A to point B. It involves shooting neutrinos through the earth from Fermilab in Illinois to a huge detector at the Sanford Underground Lab.

    The man in charge of the facility, executive director Brookings native Mike Headley says they are excited to be a part of the project.

    “This will really be a big deal”, said Headley. “It’s an international collaboration that has close to 150 institutions worldwide and over 700 collaborators. The Long Base Neutrino Experiment (also called DUNE) is basically a $1.5 billion project. It is 1/3 funded international 2/3 funded in U.S. About 300 million of that $1.5 Billion will be facility construction here in South Dakota, so it’s going to be one of the biggest construction projects we’ve ever had in the state.”

    Construction on DUNE will begin next year. Scientists behind the project say neutrinos could hold clues about how the universe began and why matter greatly outnumbers antimatter, allowing us to exist.

    See the full article here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s. In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE) [being replaced by DUNE]—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE [DUNE] will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

     
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