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  • richardmitnick 5:38 pm on June 11, 2018 Permalink | Reply
    Tags: , , , Neutrinos   

    From MIT News: “3 Questions: Pinning down a neutrino’s mass” 

    MIT News
    MIT Widget

    From MIT News

    June 8, 2018
    Jennifer Chu

    1
    The Karlsruhe Tritium Neutrino Experiment, or KATRIN, is a massive detector based in the town of Karlsruhe, Germany, that has been designed to measure a neutrino’s mass with far greater precision than existing experiments. Image: Karlsruhe/KIT Katrin

    KIT Katrin experiment

    KATRIN Experiment schematic

    Neutrinos are everywhere, and yet their presence is rarely felt. Scientists have assumed for decades that, because they interact so little with matter, neutrinos must lack any measurable mass. But recent experiments have shown that these “ghostly” particles do in fact hold some weight. Ever since, the hunt has been on to pin down a neutrino’s mass — a vanishingly small measurement that could have huge implications for our understanding of how the universe has evolved.

    Today, a major experiment has joined this fundamental search. The Karlsruhe Tritium Neutrino Experiment, or KATRIN, is a massive detector based in the town of Karlsruhe, Germany, that has been designed to measure a neutrino’s mass with far greater precision than existing experiments. At KATRIN’s heart is a 200-ton, zeppelin-like spectrometer, and scientists hope that with the experiment launching today they can start to collect data that in the next few years will give them a better idea of just how massive neutrinos can be.

    Professor of physics Joseph Formaggio is part of the team of scientists that will get a first look at KATRIN’s data as they come in. Formaggio and others from MIT helped construct part of the detector’s apparatus and developed software to simulate the trajectory of particles passing through the detector. His group is now working along with a team of scientists around the world on software to analyze the data for signs of neutrino mass. MIT News sat down with Formaggio ahead of the experiment’s launch, for a chat about KATRIN and the monumental structure built to search for an infinitesimal signal.

    Q: How will KATRIN measure the mass of a neutrino?

    A: KATRIN is addressing a very old question, one that was posed by [Enrico] Fermi in the 1930s, which is the question of how much mass a neutrino has. Decades ago, we thought the neutrino had to be massless. Then experiments in neutrino oscillations showed that no, that wasn’t actually true — neutrinos actually have a tiny mass. And now we know that different neutrinos have different masses from each other. What we don’t know is how much any one neutrino weighs — the absolute mass is still unknown.

    KATRIN addresses this question by looking at energy conservation: E = mc2. We have a radioactive gas, in this case, tritium, that releases energy as it decays. Some of that energy goes to a neutrino, which flies off and we never see it again. Some of that energy goes to an electron, and if you measure the electron’s energy very precisely, it turns out that tells you how much the neutrino took away. And in particular, was that energy all kinetic, because the neutrino was going away at the speed of light? Or does it have a little bit of rest energy, or mass?

    The experiment itself is about 70 meters long — almost a football field but not quite. Tritium is injected at one end, into a windowless tube, where there are millions of decays happening per second, all of which will produce electrons. The gas sits inside a magnet, and the electrons, because they’re charged, see this magnetic field, and they begin to follow the magnetic field lines out of the gas region and into a huge spectrometer — one of the largest vacuums in the world. The magnetic field is very weak in the spectrometer, and the field lines will start to spread out. The spectrometer is held at an electric potential of nearly 20,000 volts, which acts like a hill: Electrons that have enough energy will make it over this hill and come out the other side of the spectrometer. The ones that don’t have enough energy get turned back.

    Then there’s another set of magnets at the very end of this long beam line, where the field lines get tighter, the electrons focus back in, and they land on a detector that just counts electrons. This is a very precise way of scanning electron energies from this very hot, radioactive source. And that’s what allows us to get the energy resolution we need, to say something about neutrino mass.

    Q: What is the current estimate for a neutrino’s mass, and how will you know you’ve reached an even more precise measurement?

    A: We have some idea of what the neutrino mass scale should be. Previous experiments have told us that it’s somewhere between 10 millielectronvolts and 2 electronvolts. An electron, which is the other lightest particle that we know about, has a mass of about 511,000 electronvolts. So somewhere between 10 meV and 2eV is our playground.

    If the neutrino does have a mass, what does it look like in our experiment? What we do is we image the spectrum of electron energies. If the neutrino has a mass, it looks like a kink in our spectrum. So we look for that kink, which would mean that the neutrino has both kinetic energy, which we expect, but also rest energy. If it were all kinetic, then it has no mass, and it’s zipping along at the speed of light. If you observe a kink, it’s as if you made a neutrino that stood still. Things can’t stay still if they are massless. The kink is evidence that you produce just a few neutrinos that were standing still. You didn’t see them directly, but you saw the electron didn’t take the energy that it was supposed to, and that energy went into the neutrino.

    Q: In what ways would a more precise neutrino mass change our understanding of the universe?

    A: For other particles like the top quark and the electron, we might not understand why they have the masses they do, but we understand how they have mass. For the neutrino, that’s an open question. How the neutrino gets its mass is unknown. The hope is, by measuring the mass of the neutrino, you get a better sense of how a neutrino gets its mass. We have billions of neutrinos everywhere in the universe. If all of a sudden they have a mass, they will impact how the universe will evolve over time. For cosmologists, that information will be very useful.

    So there’s a little bit of, what’s going to happen when we actually make a measurement? Will we see something massive? There is a possibility for surprise, and that could be most exciting, because it would mean we really don’t understand what we’re doing, and that’s usually good for us.

    This is a long experiment coming. I joined the experiment when I was a postdoc in 2003, and there were people thinking about it even before then. It’s taken a long time, and it’s an incredible marvel of engineering. Because each time, they’ve had to solve a problem that didn’t have a solution yet. How do you build a tank of that size, and evacuate it so that it’s in vacuum? The tank is empty. Of air! And it’s a huge tank, one of the largest vacuums in the world. That’s an engineering feat. How do you keep the radioactive gas cold and stable to a few millikelvin? All these things really took a lot of engineering, and it’s a beautiful experiment. Now we get to take data, and that’s going to be very exciting.

    See the full article here .


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  • richardmitnick 2:10 pm on June 8, 2018 Permalink | Reply
    Tags: , , , Neutrinos,   

    From Fermilab: “A boon for physicists: new insights into neutrino interactions” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    June 8, 2018
    1
    Image of a 3-track neutrino event in the MicroBooNE data with a muon, charged pion, and proton candidate in the final state. Image: MicroBooNE collaboration

    Physicists on the MicroBooNE collaboration at the Department of Energy’s Fermilab have produced their first collection of science results. Roxanne Guenette of Harvard University presented the results on behalf of the collaboration at the international Neutrino 2018 conference in Germany. The measurements are of three independent quantities that describe neutrino interactions with argon atoms, which make up the 170 tons of total target material used for neutrino collisions inside the MicroBooNE detector.

    MicroBooNE started operations in the fall of 2015. The detector, about the size of a school bus, has recorded hundreds of thousands of neutrino-argon collisions since then. It features a time projection chamber with three wire planes that record the particle tracks created by those collisions, similar to a digital camera recording images of fireworks. The Booster particle accelerator at Fermilab is used to create the muon neutrino beam for the experiment.

    It is the first low-energy neutrino experiment to make detailed observations of the subatomic processes that happen when a muon neutrino hits and interacts with an argon atom, leading to showers of secondary particles including protons, pions, muons and more. Using noise-reducing analysis techniques, MicroBooNE scientists can interpret the precise images of the particle tracks.

    One of the new results reported at the Neutrino 2018 conference was the first measurement of the multiplicity – or number of particles – that these neutrino-argon collisions generate. A new paper describing these results was submitted to the journal Physical Review D last week. Other measurements determined the likelihood, or more precisely the cross section, of a neutrino-argon collision occurring and producing a neutral pion or a more inclusive final state.

    The new results are of great importance for the groundbreaking measurements to be performed by neutrino experiments with liquid-argon TPCs. This includes the search for a fourth type of neutrino with the Short-Baseline Neutrino program at Fermilab, which comprises three neutrino detectors: the ICARUS detector, built by Italy’s INFN, refurbished at CERN, and then shipped to Fermilab in 2017; the new Short Baseline Near Detector; and MicroBooNE.

    FNAL/ICARUS

    FNAL Short Baseline near Detector

    FNAL Near Detector

    FNAL/MicroBooNE

    The measurements are also important for the international Deep Underground Neutrino Experiment hosted by Fermilab, which will use both neutrino and antineutrino collisions with argon to search for differences between neutrino and antineutrino interactions, with the goal of understanding what role neutrinos played in the evolution of the universe.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    “We are building on the success of neutrino interaction measurements in ICARUS and ArgoNeuT now with much larger statistics in MicroBooNE, to enable precise cross section measurements on argon,” said MicroBooNE co-spokesperson Bonnie Fleming, who holds a joint appointment with Fermilab and Yale University. “These are the first high-statistics, precision measurements on argon. They will be critical for the DUNE program.”

    Nearly 200 scientists from 31 institutions in Israel, Switzerland, Turkey, the United Kingdom and the United States are members of the MicroBooNE collaboration. The experiment is funded by the U.S. Department of Energy Office of Science.

    See the full article here .


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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 3:57 pm on June 4, 2018 Permalink | Reply
    Tags: , , Neutrinos, , ,   

    From physicsworld.com: “Evidence for sterile neutrinos claimed by Fermilab experiment” 

    physicsworld
    From physicsworld.com

    04 Jun 2018
    Edwin Cartlidge

    Physicists working on the Mini Booster Neutrino Experiment (MiniBooNE) at Fermilab in the US have released new results that they argue provide strong evidence for the existence of a new type of particle known as a sterile neutrino. The researchers say that their data are fully consistent with a previous hint of sterile neutrinos that emerged more than 20 years ago from the Liquid Scintillator Neutrino Detector (LSND) at the Los Alamos National Laboratory in New Mexico, although other groups have failed to reproduce the findings.

    FNAL/MiniBooNE

    Sterile neutrinos, if they exist, would be even more elusive than standard neutrinos, which themselves are chargeless and nearly massless. The Standard Model of particle physics tells us that neutrinos come in three flavours – electron, muon and tau – and that they “oscillate” from one flavour to another as they travel through space. But some extensions of the Standard Model predict that these known neutrinos can also oscillate into and out of sterile neutrinos, which might not interact at all with any other ordinary matter.

    MiniBooNE monitors the tiny flashes of light that are produced occasionally when electron neutrinos interact with atomic nuclei in about 800 tonnes of pure mineral oil contained in a spherical tank located underground on the Fermilab site near Chicago.

    MiniBooNE receptors

    Those neutrinos are generated after protons from the lab’s Booster accelerator are fired into a beryllium target to create muon neutrinos, which then oscillate to electron neutrinos as they travel several hundred metres through the Earth to the detector.

    Statistically speaking

    In a preprint uploaded recently to the arXiv server, the MiniBooNE collaboration reports having detected far more electron neutrinos than would be expected from purely Standard Model oscillations after collecting data for 15 years. According to collaboration member William Louis of Los Alamos, the measurement suggests that some of the muon neutrinos oscillate into sterile neutrinos that in turn transform into electron neutrinos. That interpretation, he says, is bolstered by the fact that the variation of electron-neutrino excess with neutrino energy – a parameter of neutrino oscillations – seen in MiniBooNE matches that recorded at Liquid Scintillator Neutrino Detector. He and his colleagues conclude that the combined excess from the two experiments has a statistical significance of 6.1σ, which is well above the 5σ that is normally considered a discovery in particle physics.

    Although MiniBooNE is quite similar to LSND – in using mineral oil to observe neutrinos from an accelerator-based source – and indeed has inherited personnel from the earlier project, its researchers are nevertheless confident that there are no common sources of error. “We think that is very unlikely,” says Louis. “The two experiments have very different energies and backgrounds, and therefore very different possible systematic errors”.

    Not a done deal

    However, the existence of sterile neutrinos is not yet a done deal. While some groups operating experiments that exploit neutrinos from nuclear reactors or radioactive sources have also gathered (somewhat weaker) evidence for the hypothetical particles, other groups have looked and found nothing. These include the IceCube collaboration, which operates a detector at the South Pole, and the now completed Main Injector Neutrino Oscillation Search (MINOS) at Fermilab.

    U Wisconsin ICECUBE neutrino detector at the South Pole

    U Wisconsin ICECUBE neutrino detector at the South Pole

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    FNAL MINOS experiment

    FNAL Minos map

    FNAL MINOS near detector

    FNAL MINOS Far Detector in the Soudan Mine in northern Minnesota

    Indeed, some physicists outside the MiniBooNE collaboration have told Physics World that they remain unconvinced by the latest results.

    To try and settle the issue, numerous other dedicated experiments are either operating or under development. For their part, Louis and colleagues are currently setting up another three detectors at Fermilab – one of which is now running – to monitor the neutrino flux closer to the beryllium target than MiniBooNE and also further away. The idea, he says, is to show beyond doubt that the electron neutrino excess really is due to oscillations, given that the measured oscillation rate should vary with distance from the source as well as with energy. Results are expected “over the next three to five years,” he says.

    See the full article here .


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    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.

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  • richardmitnick 10:55 am on June 4, 2018 Permalink | Reply
    Tags: , , , Neutrinos, ,   

    From Fermilab: “NOvA experiment sees strong evidence for antineutrino oscillation” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    June 4th, 2018

    Science contact
    Peter Shanahan, co-spokesperson for NOvA, Fermilab
    shanahan@fnal.gov
    630-840-8378

    Tricia Vahle, NOvA co-spokesperson, William & Mary
    plvahle@wm.edu
    757-221-3559

    Media contact
    Andre Salles, Fermilab Office of Communication,
    asalles@fnal.gov
    630-840-6733

    For more than three years, scientists on the NOvA collaboration have been observing particles called neutrinos as they oscillate from one type to another over a distance of 500 miles. Now, in a new result unveiled today at the Neutrino 2018 conference in Heidelberg, Germany, the collaboration has announced its first results using antineutrinos, and has seen strong evidence of muon antineutrinos oscillating into electron antineutrinos, a phenomenon that has never been unambiguously observed.

    3
    This display shows, from two perspectives, an electron antineutrino appearance candidate in the NOvA far detector. Image courtesy of Evan Niner/NOvA collaboration

    FNAL NOvA Near Detector

    NOvA Far detector 15 metric-kiloton far detector in Minnesota just south of the U.S.-Canada border schematic

    NOvA Far Detector Block

    NOvA, based at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, is the world’s longest-baseline neutrino experiment. Its purpose is to discover more about neutrinos, ghostly yet abundant particles that travel through matter mostly without leaving a trace. The experiment’s long-term goal is to look for similarities and differences in how neutrinos and antineutrinos change from one type – in this case, muon – into one of the other two types, electron or tau. Precisely measuring this change in both neutrinos and antineutrinos, and then comparing them, will help scientists unlock the secrets that these particles hold about how the universe operates.

    NOvA uses two large particle detectors – a smaller one at Fermilab in Illinois, and a much larger one 500 miles away in northern Minnesota – to study a beam of particles generated by Fermilab’s accelerator complex and sent through the earth, with no tunnel required.

    The new result is drawn from NOvA’s first run with antineutrinos, the antimatter counterpart to neutrinos. NOvA began studying antineutrinos in February of 2017. Fermilab’s accelerators create a beam of muon neutrinos (or muon antineutrinos), and NOvA’s far detector is specifically designed to see those particles changing into electron neutrinos (or electron antineutrinos) on their journey.

    If antineutrinos did not oscillate from muon type to electron type, scientists would have expected to record just five electron antineutrino candidates in the NOvA far detector during this first run. But when they analyzed the data, they found 18, providing strong evidence that antineutrinos undergo this oscillation.

    “Antineutrinos are more difficult to make than neutrinos, and they are less likely to interact in our detector,” said Fermilab’s Peter Shanahan, co-spokesperson of the NOvA collaboration. “This first data set is a fraction of our goal, but the number of oscillation events we see is far greater than we would expect if antineutrinos didn’t oscillate from muon type to electron. It demonstrates the impact that Fermilab’s high-power particle beam has on our ability to study neutrinos and antineutrinos.”

    Although antineutrinos are known to oscillate, the change into electron antineutrinos over long distances has not yet been definitively observed. The T2K experiment, located in Japan, announced that it had observed hints of this phenomenon in 2017.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan


    T2K Experiment, Tokai to Kamioka, Japan

    The NOvA and T2K collaborations are working toward a combined analysis of their data in the coming years.

    “With this first result using antineutrinos, NOvA has moved into the next phase of its scientific program,” said Jim Siegrist, Associate Director for High Energy Physics at the Department of Energy Office of Science. “I’m pleased to see this important experiment continuing to tell us more about these fascinating particles.”

    NOvA’s new antineutrino result accompanies an improvement to its methods of analysis, leading to a more precise measurement of its neutrino data. From 2014 to 2017, NOvA saw 58 candidates for interactions from muon neutrinos changing into electron neutrinos, and scientists are using this data to move closer to unraveling some of the knottiest mysteries of these elusive particles.

    The key to NOvA’s science program is comparing the rate at which electron neutrinos appear in the far detector with the rate that electron antineutrinos appear. A precise measurement of those differences will allow NOvA to achieve one of its main science goals: to determine which of the three types of neutrinos is the heaviest, and which the lightest.

    Neutrinos have been shown to have mass, but scientists have not been able to directly measure that mass. However, with enough data, they can determine the relative masses of the three, a puzzle called the mass ordering. NOvA is working toward a definitive answer to this question. Scientists on the experiment will continue studying antineutrinos through 2019, and over the following years will eventually collect equal amounts of data from neutrinos and antineutrinos.

    “This first data set from antineutrinos is a just a start to what promises to be an exciting run,” said NOvA co-spokesperson Tricia Vahle of William & Mary. “It’s early days, but NOvA is already giving us new insights into the many mysteries of neutrinos and antineutrinos.”

    For more information on neutrinos and neutrino research, please visit http://neutrinos.fnal.gov.

    The NOvA collaboration includes more than 240 scientists from nearly 50 institutions in seven countries: Brazil, Colombia, Czech Republic, India, Russia, the U.K. and the U.S. For more information visit the experiment’s website at http://novaexperiment.fnal.gov.

    See the full article here .


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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

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    FNAL Holometer

     
  • richardmitnick 5:26 pm on May 31, 2018 Permalink | Reply
    Tags: , , MicroBooNE measures charged-particle multiplicity in first neutrino-beam-based result, Neutrinos,   

    From Fermilab: “MicroBooNE measures charged-particle multiplicity in first neutrino-beam-based result” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    May 31, 2018
    Tim Bolton
    Aleena Rafique

    FNAL/MicrobooNE

    2
    This plot shows the observed multiplicity of charged particles emerging from the neutrino interaction point in MicroBooNE data (points with error bars) and three models (histograms). Data favors lower multiplicity compared to all the models.

    Neutrinos from the sun, from cosmic rays, from nuclear reactors, from radioactive decays in the earth, from exploded supernovas, from the Big Bang itself, and even occasionally from particle accelerators rush through our body every second in enormous quantity with no notice at all on our part. To detect neutrinos requires that they interact, and to first approximation, the theory of these interactions could not be simpler: They don’t. However, the very occasional scattering of a neutrino could allow us to unlock some of nature’s biggest remaining secrets.

    To study neutrinos we must enhance their rate of interactions, and this we do by boosting their energies using accelerators such as those at Fermilab and by building massive instrumented targets to give them more chance to bounce off of something. The technology of choice for this at Fermilab is the liquid-argon time projection chamber. This forms the heart of the MicroBooNE experiment’s 170-ton neutrino target, which intercepts the intense neutrino flux generated by Fermilab’s Booster Neutrino Beam. The same technology will in a decade enable the DUNE experiment’s 40,000-ton far detector, sited underground in South Dakota, to receive an even more intense beam generated 1,300 kilometers east at Fermilab.

    The path to extracting deeper science from neutrinos starts with understanding the details of their interactions, which means not only the manner in which they scatter from protons and neutrons, but also the effects of the argon nuclear volume on this scattering.

    MicroBooNE’s first neutrino-beam-based physics result, submitted to the journal Physics Review D this spring, launches the experiment’s journey along this path.

    3
    This plot shows the azimuthal angle difference distribution for events with an observed multiplicity of two for data (points with error bars) and model (histogram). The peaks near positive and negative pi indicate presence of the quasielastic scattering process, while the distribution between the peaks is consistent with predicted contributions from resonance production. The shaded blue area is the estimated cosmic ray background.

    The paper first describes a technique to extract neutrino events from a cosmic ray background-dominated sample using fully automatic reconstruction tools. Then it presents the number of charged particles that emerge from a neutrino interaction point — the charged-particle multiplicity — and compares it against three different versions of the neutrino event generator GENIE. Hints at a discrepancy with model are observed in higher multiplicities, where models predict more events than are observed in data. Finally, it compares many charged-particle kinematic distributions from different multiplicities to GENIE models, providing indications of interesting nuclear physics effects on the scattering. In the end, despite discrepancies here and there, MicroBooNE data agree reasonably well with all three GENIE models.

    This measurement starts up the MicroBooNE neutrino interactions physics program. It validates the use of GENIE, an important analysis tool, but it also points out areas where models can be improved.

    In addition to their intrinsic scientific interest, neutrino interaction measurements at MicroBooNE will be very useful for many detectors, such as SBND, ICARUS, and DUNE, that will use the same technology and target.

    See the full article here .


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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 2:06 pm on May 22, 2018 Permalink | Reply
    Tags: , , Neutrinos, Opera collaboration at Gran Sasso,   

    From CERN: OPERA presents its final results on neutrino oscillations 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    OPERA at Gran Sasso (Image: INFN)

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    22 May 2018
    Achintya Rao

    The OPERA experiment, located at the Gran Sasso Laboratory of the Italian National Institute for Nuclear Physics (INFN), was designed to conclusively prove that muon-neutrinos can convert to tau-neutrinos, through a process called neutrino oscillation, whose discovery was awarded the 2015 Nobel Physics Prize. In a paper published today in the journal Physical Review Letters, the OPERA collaboration reports the observation of a total of 10 candidate events for a muon to tau-neutrino conversion, in what are the very final results of the experiment. This demonstrates unambiguously that muon neutrinos oscillate into tau neutrinos on their way from CERN, where muon neutrinos were produced, to the Gran Sasso Laboratory 730 km away, where OPERA detected the ten tau neutrino candidates.

    Today the OPERA collaboration has also made their data public through the CERN Open Data Portal. By releasing the data into the public domain, researchers outside the OPERA Collaboration have the opportunity to conduct novel research with them. The datasets provided come with rich context information to help interpret the data, also for educational use. A visualiser enables users to see the different events and download them. This is the first non-LHC data release through the CERN Open Data portal, a service launched in 2014.

    There are three kinds of neutrinos in nature: electron, muon and tau neutrinos. They can be distinguished by the property that, when interacting with matter, they typically convert into the electrically charged lepton carrying their name: electron, muon and tau leptons. It is these leptons that are seen by detectors, such as the OPERA detector, unique in its capability of observing all three. Experiments carried out around the turn of the millennium showed that muon neutrinos, after travelling long distances, create fewer muons than expected, when interacting with a detector. This suggested that muon neutrinos were oscillating into other types of neutrinos. Since there was no change in the number of detected electrons, physicists suggested that muon neutrinos were primarily oscillating into tau neutrinos. This has now been unambiguously confirmed by OPERA, through the direct observation of tau neutrinos appearing hundreds of kilometres away from the muon neutrino source. The clarification of the oscillation patterns of neutrinos sheds light on some of the properties of these mysterious particles, such as their mass.

    The OPERA collaboration observed the first tau-lepton event (evidence of muon-neutrino oscillation) in 2010, followed by four additional events reported between 2012 and 2015, when the discovery of tau neutrino appearance was first assessed. Thanks to a new analysis strategy applied to the full data sample collected between 2008 and 2012 – the period of neutrino production – a total of 10 candidate events have now been identified, with an extremely high level of significance.

    “We have analysed everything with a completely new strategy, taking into account the peculiar features of the events,” said Giovanni De Lellis Spokesperson for the OPERA collaboration. “We also report the first direct observation of the tau neutrino lepton number, the parameter that discriminates neutrinos from their antimatter counterpart, antineutrinos. It is extremely gratifying to see today that our legacy results largely exceed the level of confidence we had envisaged in the experiment proposal.”

    Beyond the contribution of the experiment to a better understanding of the way neutrinos behave, the development of new technologies is also part of the legacy of OPERA. The collaboration was the first to develop fully automated, high-speed readout technologies with sub-micrometric accuracy, which pioneered the large-scale use of the so-called nuclear emulsion films to record particle tracks. Nuclear emulsion technology finds applications in a wide range of other scientific areas from dark matter search to volcano and glacier investigation. It is also applied to optimise the hadron therapy for cancer treatment and was recently used to map out the interior of the Great Pyramid, one of the oldest and largest monuments on Earth, built during the dynasty of the pharaoh Khufu, also known as Cheops.

    See the full article here.


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    Please help promote STEM in your local schools.
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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    OTHER PROJECTS AT CERN

    CERN AEGIS

    CERN ALPHA

    CERN ALPHA

    CERN AMS

    CERN ACACUSA

    CERN ASACUSA

    CERN ATRAP

    CERN ATRAP

    CERN AWAKE

    CERN AWAKE

    CERN CAST

    CERN CAST Axion Solar Telescope

    CERN CLOUD

    CERN CLOUD

    CERN COMPASS

    CERN COMPASS

    CERN DIRAC

    CERN DIRAC

    CERN ISOLDE

    CERN ISOLDE

    CERN LHCf

    CERN LHCf

    CERN NA62

    CERN NA62

    CERN NTOF

    CERN TOTEM

    CERN UA9

     
  • richardmitnick 5:54 pm on May 17, 2018 Permalink | Reply
    Tags: , Five (more) fascinating facts about DUNE, , , LBNF/DUNE, Neutrinos, ,   

    From Symmetry: “Five (more) fascinating facts about DUNE” 

    Symmetry Mag
    From Symmetry

    05/17/18
    Lauren Biron

    Engineering the incredible, dependable, shrinkable Deep Underground Neutrino Experiment.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    The Deep Underground Neutrino Experiment, designed to solve mysteries about tiny particles called neutrinos, is growing by the day. More than 1000 scientists from over 30 countries are now collaborating on the project. Construction of prototype detectors is well underway.

    Engineers are getting ready to carve out space for the mammoth particle detector a mile below ground.

    The international project is hosted by the Department of Energy’s Fermi National Accelerator Laboratory outside of Chicago—and it has people cracking engineering puzzles all around the globe. Here are five incredible engineering and design feats related to building the biggest liquid-argon neutrino experiment in the world.

    1. The DUNE detector modules can (and will) shrink by about half a foot (16.5 centimeters) when filled with liquid argon.
    2
    Artwork by Sandbox Studio, Chicago with Ana Kova

    Each of the large DUNE detector modules in South Dakota will be about 175 feet (58 meters) long, but everything has to be able to comfortably shrink when chilled to negative 300 degrees Fahrenheit (negative 184 degrees Celsius). The exterior box that holds all of cold material and detector components, also known as the cryostat, will survive thanks to something akin to origami. It will be made of square panels with folds on all sides, creating raised bumps or corrugations around each square. As DUNE cools by hundreds of degrees to liquid argon temperatures, the vessel can actually stay the same size because of those folds; the corrugation provides extra material that can spread out as the flat areas shrink. But inside, the components will be on the move. Many of the major detector components within the cryostat will be attached to the ceiling with a dynamic suspension system that allows them to move up to half a foot as they chill.

    2. Researchers must engineer a new kind of target to withstand the barrage of particles it will take to make the world’s most intense high-energy neutrino beam for DUNE.

    3
    Artwork by Sandbox Studio, Chicago with Ana Kova
    Targets are the material that a proton beam interacts with to produce neutrinos. The Fermilab accelerator complex is being upgraded with a new superconducting linear collider at the start of the accelerator chain to produce an even more powerful proton beam for DUNE—and that means engineers need a more robust target that can stand up to the intense onslaught of particles. Current neutrino beamlines at Fermilab use different targets—one with meter-long rows of water-cooled graphite tiles called fins, another with air-cooled beryllium. But engineers are working on a new helium-gas-cooled cylindrical rod target to meet the higher intensity. How intense is it? The new accelerator chain’s beam power will be delivered in short pulses with an instantaneous power of about 150 gigawatts, equivalent to powering 15 billion 100-watt lightbulbs at the same time for a fraction of a second.

    3. A single DUNE test detector component requires almost 15 miles of wire.
    4
    Artwork by Sandbox Studio, Chicago with Ana Kova
    Before scientists start building the liquid-argon neutrino detectors a mile under the surface in South Dakota, they want to be sure their technology is going to work as expected. In a ProtoDUNE test detector being constructed at CERN, they are testing pieces called “anode plane assemblies.”

    ProtoDune

    CERN Proto DUNE Maximillian Brice

    ProtoDune

    Each of these panels is made of almost 15 miles (24 kilometers) of precisely tensioned wire that has to lay flat—within a few millimeters. The wire is a mere 150 microns thick—about the width of two hairs. This panel of wires will attract and detect particles produced when neutrinos interact with the liquid argon in the detector—and hundreds will be needed for DUNE.

    4. DUNE will be the highest voltage liquid-argon experiment in the world.

    6
    Artwork by Sandbox Studio, Chicago with Ana Kova

    The four DUNE far detector modules, which will sit a mile underground at the Sanford Underground Research Facility in South Dakota, will use electrical components called field cages. These will capture particle tracks set in motion by a neutrino interaction. The different modules will feature different field cage designs, one of which has a target voltage of around 180,000 volts—about 1500 times as much voltage as you’d find in your kitchen toaster—while the other design is planning for 600,000 volts. This is much more than was produced by previous liquid-argon experiments like MicroBooNE and ICARUS (now both part of Fermilab’s short-baseline neutrino program), which typically operate between 70,000 and 80,000 volts. Building such a high-voltage experiment requires design creativity. Even “simple” things, from protecting against power surges and designing feedthroughs—the fancy plugs that bring this high voltage from the power supply to the detector—have to be carefully considered and, in some cases, built from scratch.

    5. Researchers expect DUNE’s data system to catch about 10 neutrinos per day—but must be able to catch thousands in seconds if a star goes supernova nearby.

    6
    Artwork by Sandbox Studio, Chicago with Ana Kova

    A supernova is a giant explosion that occurs when a star collapses in on itself. Most people imagine the dramatic burst of light and heat, but much of the energy (around 99 percent) is carried away by neutrinos that can then be recorded here on Earth in neutrino detectors. On an average day, DUNE will typically see a handful of neutrinos coming from the world’s most intense high-energy neutrino beam—around 10 per day at the start of the experiment. Because neutrinos interact very rarely with other matter; scientists must send trillions to their distant detectors to catch even a few. But so many neutrinos are released by a supernova that the detector could see several thousand neutrinos within seconds if a star explodes in our Milky Way galaxy. A dedicated group within DUNE is working on how best to rapidly record the enormous amount of data from a supernova, which will be about 50 terabytes in ten seconds.

    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 9:43 am on April 16, 2018 Permalink | Reply
    Tags: , , Neutrinos, , , U.S. and India sign agreement providing for neutrino physics collaboration at Fermilab and in India   

    From FNAL: “U.S., India sign agreement providing for neutrino physics collaboration at Fermilab and in India” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    April 16, 2018

    1
    U.S. Secretary of Energy Rick Perry, left, and Indian Atomic Energy Secretary Sekhar Basu, right, signed an agreement on Monday in New Delhi, opening the door for continued cooperation on neutrino research in both countries. In attendance were Hema Ramamoorthi, chief of staff of the U.S. DOE’s Fermi National Accelerator Laboratory, and U.S. Ambassador to India Kenneth Juster. Photo: Fermilab.

    Earlier today, April 16, 2018, U.S. Secretary of Energy Rick Perry and India’s Atomic Energy Secretary Dr. Sekhar Basu signed an agreement in New Delhi to expand the two countries’ collaboration on world-leading science and technology projects. It opens the way for jointly advancing cutting-edge neutrino science projects under way in both countries: the Long-Baseline Neutrino Facility (LBNF) with the international Deep Underground Neutrino Experiment (DUNE) hosted at the U.S. Department of Energy’s Fermilab and the India-based Neutrino Observatory (INO).

    LBNF/DUNE brings together scientists from around the world to discover the role that tiny particles known as neutrinos play in the universe. More than 1,000 scientists from over 170 institutions in 31 countries work on LBNF/DUNE and celebrated its groundbreaking in July 2017. The project will use Fermilab’s powerful particle accelerators to send the world’s most intense beam of high-energy neutrinos to massive neutrino detectors that will explore their interactions with matter.

    INO scientists will observe neutrinos that are produced in Earth’s atmosphere to answer questions about the properties of these elusive particles. Scientists from more than 20 institutions are working on INO.

    “The LBNF/DUNE project hosted by the Department of Energy’s Fermilab is an important priority for the DOE and America’s leadership in science, in collaboration with our international partners,” said Secretary of Energy Rick Perry. “We are pleased to expand our partnership with India in neutrino science and look forward to making discoveries in this promising area of research.”

    Scientists from the United States and India have a long history of scientific collaboration, including the discovery of the top quark at Fermilab.

    “India has a rich tradition of discoveries in basic science,” said Atomic Energy Secretary Basu. “We are pleased to expand our accelerator science collaboration with the U.S. to include the science for neutrinos. Science knows no borders, and we value our Indian scientists working hand-in-hand with our American colleagues. The pursuit of knowledge is a true human endeavor.”

    This DOE-DAE agreement builds on the two countries’ existing collaboration on particle accelerator technologies. In 2013, DOE and DAE signed an agreement authorizing the joint development and construction of particle accelerator components in preparation for projects at Fermilab and in India. This collaborative work includes the training of Indian scientists in the United States and India’s development and prototyping of components for upgrades to Fermilab’s particle accelerator complex for LBNF/DUNE. The upgrades, known as the Proton Improvement Plan-II (PIP-II), include the construction of a 600-foot-long superconducting linear accelerator at Fermilab. It will be the first ever particle accelerator built in the United States with significant contributions from international partners, including also the UK and Italy. Scientists from four institutions in India – BARC in Mumbai, IUAC in New Delhi, RRCAT in Indore and VECC in Kolkata – are contributing to the design and construction of magnets and superconducting particle accelerator components for PIP-II at Fermilab and the next generation of particle accelerators in India.

    Under the new agreement signed today, U.S. and Indian institutions will expand this productive collaboration to include neutrino research projects. The LBNF/DUNE project will use the upgraded Fermilab particle accelerator complex to send the world’s most powerful neutrino beam 800 miles (1,300 kilometers) through the earth to a massive neutrino detector located at Sanford Underground Research Facility in South Dakota. This detector will use almost 70,000 tons of liquid argon to detect neutrinos and will be located about a mile (1.5 kilometers) underground; an additional detector will measure the neutrino beam at Fermilab as it leaves the accelerator complex. Prototype neutrino detectors already are under construction at the European research center CERN, another partner in LBNF/DUNE.

    “Fermilab’s international collaboration with India and other countries for LBNF/DUNE and PIP-II is a win-win situation for everybody involved,” said Fermilab Director Nigel Lockyer. “Our partners get to work with and learn from some of the best particle accelerator and particle detector experts in the world at Fermilab, and we benefit from their contributions to some of the most complex scientific machines in the world, including LBNF/DUNE and the PIP-II accelerator.”

    INO will use a different technology — known as an iron calorimeter — to record information about neutrinos and antineutrinos generated by cosmic rays hitting Earth’s atmosphere. Its detector will feature what could be the world’s biggest magnet, allowing INO to be the first experiment able to distinguish signals produced by atmospheric neutrinos and antineutrinos. The DOE-DAE agreement enables U.S. and Indian scientists to collaborate on the development and construction of these different types of neutrino detectors. More than a dozen Indian institutions are involved in the collaboration on neutrino research.

    Additional quotes:

    Prof. Vivek Datar, INO spokesperson and project director, Taha Institute of Fundamental Research:

    “This will facilitate U.S. participation in building some of the hardware for INO, while Indian scientists do the same for the DUNE experiment. It will also help in building expertise in India in cutting-edge detector technology, such as in liquid-argon detectors, where Fermilab will be at the forefront. At the same time we will also pursue some new ideas.”

    Prof. Naba Mondal, former INO spokesperson, Saha Institute of Nuclear Physics:

    “This agreement is a positive step towards making INO a global center for fundamental research. Students working at INO will get opportunities to interact with international experts.”

    Prof. Ed Blucher, DUNE co-spokesperson, University of Chicago, United States:

    “The international DUNE experiment could fundamentally change our understanding of the universe. Contributions from India and other partner countries will enable us to build the world’s most technologically advanced neutrino detectors as we aim to make groundbreaking discoveries regarding the origin of matter, the unification of forces, and the formation of neutron stars and black holes.”

    Prof. Stefan Soldner-Rembold, DUNE co-spokesperson, University of Manchester, UK:

    “DUNE will be the world’s most ambitious neutrino experiment, driven by the commitment and expertise of scientists in more than 30 countries. We are looking forward to the contributions that our colleagues in India will make to this extraordinary project.”

    To learn more about LBNF/DUNE, visit http://www.fnal.gov/dunemedia. More information about PIP-II is available at http://pip2.fnal.gov.

    See the full article here .

    Please help promote STEM in your local schools.

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    FNAL Icon

    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.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

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

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

    U Wisconsin ICECUBE neutrino detector at the South Pole

    IceCube neutrino detector interior

    IceCube Gen-2 DeepCore

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

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

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

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

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

    NASA/Fermi Gamma Ray Space Telescope


    NASA/Fermi LAT

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

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

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

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

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

    See the full article here .

    Please help promote STEM in your local schools.

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

     
  • richardmitnick 5:42 pm on April 11, 2018 Permalink | Reply
    Tags: , , , Neutrinos, , ,   

    From Symmetry: “Right on target” 

    Symmetry Mag
    Symmetry

    04/11/18
    Sarah Lawhun

    1
    Patrick Hurh

    These hardy physics components live at the center of particle production.

    For some, a target is part of a game of darts. For others, it’s a retail chain. In particle physics, it’s the site of an intense, complex environment that plays a crucial role in generating the universe’s smallest components for scientists to study.

    The target is an unsung player in particle physics experiments, often taking a back seat to scene-stealing light-speed particle beams and giant particle detectors. Yet many experiments wouldn’t exist without a target. And, make no mistake, a target that holds its own is a valuable player.

    Scientists and engineers at Fermilab [FNAL] are currently investigating targets for the study of neutrinos—mysterious particles that could hold the key to the universe’s evolution.

    Intense interactions

    The typical particle physics experiment is set up in one of two ways. In the first, two energetic particle beams collide into each other, generating a shower of other particles for scientists to study.

    In the second, the particle beam strikes a stationary, solid material—the target. In this fixed-target setup, the powerful meeting produces the particle shower.

    As the crash pad for intense beams, a target requires a hardy constitution. It has to withstand repeated onslaughts of high-power beams and hold up under hot temperatures.

    You might think that, as stalwart players in the play of particle production, targets would look like a fortress wall (or maybe you imagined dartboard). But targets take different shapes—long and thin, bulky and wide. They’re also made of different materials, depending on the kind of particle one wants to make. They can be made of metal, water or even specially designed nanofibers.

    In a fixed-target experiment, the beam—say, a proton beam—races toward the target, striking it. Protons in the beam interact with the target material’s nuclei, and the resulting particles shoot away from the target in all directions. Magnets then funnel and corral some of these newly born particles to a detector, where scientists measure their fundamental properties.

    The particle birthplace

    The particles that emerge from the beam-target interaction depend in large part on the target material. Consider Fermilab neutrino experiments.

    In these experiments, after the protons strike the target, some of the particles in the subsequent particle shower decay—or transform—into neutrinos.

    The target has to be made of just the right stuff.

    “Targets are crucial for particle physics research,” says Fermilab scientist Bob Zwaska. “They allow us to create all of these new particles, such as neutrinos, that we want to study.”

    Graphite is a goldilocks material for neutrino targets. If kept at the right temperature while in the proton beam, the graphite generates particles of just the right energy to be able to decay into neutrinos.

    For neutron targets, such as that at the Spallation Neutron Source at Oak Ridge National Laboratory [ORNL], heavier metals such as mercury are used instead.

    ORNL Spallation Neutron Source


    ORNL Spallation Neutron Source

    Maximum interaction is the goal of a target’s design. The target for Fermilab’s NOvA neutrino experiment, for example, is a straight row—about the length of your leg—of graphite fins that resemble tall dominoes.

    FNAL NOvA Near Detector


    FNAL/NOvA experiment map

    The proton beam barrels down its axis, and every encounter with a fin produces an interaction. The thin shape of the target ensures that few of the particles shooting off after collision are reabsorbed back into the target.

    Robust targets

    “As long as the scientists have the particles they need to study, they’re happy. But down the line, sometimes the targets become damaged,” says Fermilab engineer Patrick Hurh. In such cases, engineers have to turn down—or occasionally turn off—the beam power. “If the beam isn’t at full capacity or is turned off, we’re not producing as many particles as we can for science.”

    The more protons that are packed into the beam, the more interactions they have with the target, and the more particles that are produced for research. So targets need to be in tip-top shape as much as possible. This usually means replacing targets as they wear down, but engineers are always exploring ways of improving target resistance, whether it’s through design or material.

    Consider what targets are up against. It isn’t only high-energy collisions—the kinds of interactions that produce particles for study—that targets endure.

    Lower-energy interactions can have long-term, negative impacts on a target, building up heat energy inside it. As the target material rises in temperature, it becomes more vulnerable to cracking. Expanding warm areas hammer against cool areas, creating waves of energy that destabilize its structure.

    Some of the collisions in a high-energy beam can also create lightweight elements such as hydrogen or helium. These gases build up over time, creating bubbles and making the target less resistant to damage.

    A proton from the beam can even knock off an entire atom, disrupting the target’s crystal structure and causing it to lose durability.

    Clearly, being a target is no picnic, so scientists and engineers are always improving targets to better roll with a punch.

    For example, graphite, used in Fermilab’s neutrino experiments, is resistant to thermal strain. And, since it is porous, built-up gases that might normally wedge themselves between atoms and disrupt their arrangement may instead migrate to open areas in the atomic structure. The graphite is able to remain stable and withstand the waves of energy from the proton beam.

    Engineers also find ways to maintain a constant target temperature. They design it so that it’s easy to keep cool, integrating additional cooling instruments into the target design. For example, external water tubes help cool the target for Fermilab’s NOvA neutrino experiment.

    Targets for intense neutrino beams

    At Fermilab, scientists and engineers are also testing new designs for what will be the lab’s most powerful proton beam—the beam for the laboratory’s flagship Long-Baseline Neutrino Facility and Deep Underground Neutrino Experiment, known as LBNF/DUNE.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    LBNF/DUNE is scheduled to begin operation in the 2020s. The experiment requires an intense beam of high-energy neutrinos—the most intense in the world. Only the most powerful proton beam can give rise to the quantities of neutrinos LBNF/DUNE needs.

    Scientists are currently in the early testing stages for LBNF/DUNE targets, investigating materials that can withstand the high-power protons. Currently in the running are beryllium and graphite, which they’re stretching to their limits. Once they conclusively determine which material comes out on top, they’ll move to the design prototyping phase. So far, most of their tests are pointing to graphite as the best choice.

    Targets will continue to evolve and adapt. LBNF/DUNE provides just one example of next-generation targets.

    “Our research isn’t just guiding the design for LBNF/DUNE,” Hurh says. “It’s for the science itself. There will always be different and more powerful particle beams, and targets will evolve to meet the challenge.”

    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.


     
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