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  • richardmitnick 3:19 pm on September 22, 2017 Permalink | Reply
    Tags: , , Neutrinos, ,   

    From ORNL via CERN Courier: “Miniature detector first to spot coherent neutrino-nucleus scattering” 

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    Oak Ridge National Laboratory

    CERN Courier

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    Detector placement. No image credit

    The COHERENT collaboration at Oak Ridge National Laboratory (ORNL) in the US has detected coherent elastic scattering of neutrinos off nuclei for the first time. The ability to harness this process, predicted 43 years ago, offers new ways to study neutrino properties and could drastically reduce the scale of neutrino detectors.

    Neutrinos famously interact very weakly, requiring very large volumes of active material to detect their presence. Typically, neutrinos interact with individual protons or neutrons inside a nucleus, but coherent elastic neutrino-nucleus scattering (CEνNS) occurs when a neutrino interacts with an entire nucleus. For this to occur, the momentum exchanged must remain significantly small compared to the nuclear size. This restricts the process to neutrino energies below a few tens of MeV, in contrast to the charged-current interactions by which neutrinos are usually detected. The signature of CEνNS is a low-energy nuclear recoil with all nucleon wavefunctions remaining in phase, but until now the difficulty in detecting these low-energy nuclear recoils has prevented observations of CEνNS – despite the predicted cross-section for this process being the largest of all low-energy neutrino couplings.

    The COHERENT team, comprising 80 researchers from 19 institutions, used ORNL’s Spallation Neutron Source (SNS), which generates the most intense pulsed neutron beams in the world while simultaneously creating a significant yield of low-energy neutrinos.

    ORNL Spallation Neutron Source

    Approximately 5 × 1020 protons are delivered per day, each returning roughly 0.08 isotropically emitted neutrinos per flavour. The researchers placed a detector, a caesium-iodide scintillator crystal doped with sodium, 20 m from the neutrino source with shielding to reduce background events associated with the neutron-induced nuclear recoils produced from the SNS. The results favour the presence of CEνNS over its absence at the 6.7σ level, with 134±22 events observed versus 173±48 predicted.

    Crucially, the result was achieved using the world’s smallest neutrino detector, with a mass of 14.5 kg. This is a consequence of the large nuclear mass of caesium and iodine, which results in a large CEνNS cross-section.

    The intense scintillation of this material for low-energy nuclear recoils, combined with the large neutrino flux of the SNS, also contributed to the success of the measurement. In effect, CEνNS allows the same detection rates as conventional neutrino detectors that are 100 times more massive.

    “It is a nearly ideal detector choice for coherent neutrino scattering,” says lead designer Juan Collar of the University of Chicago. “However, other new coherent neutrino-detector designs are appearing over the horizon that look extraordinarily promising in order to further reduce detector mass, truly realising technological applications such as reactor monitoring.”

    Yoshi Uchida of Imperial College London, who was not involved in the study, says that detecting neutrinos via the neutral-current process as opposed to the usual charged-current process is a great advantage because it is “blind” to the type of neutrino being produced and is sensitive at low energies. “So in combination with other types of detection, it could tell us a lot about a particular neutrino source of interest.” However, he adds that the SNS set-up is very specific and that, outside such ideal conditions, it might be difficult to scale a similar detector in a way that would be of practical use. “The fact that the COHERENT collaboration already has several other target nuclei (and detection methods) being used in their set-up means there will be more to come on this subject in the near future.”

    See the full article here .

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    ORNL is managed by UT-Battelle for the Department of Energy’s Office of Science. DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.

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  • richardmitnick 12:15 pm on September 22, 2017 Permalink | Reply
    Tags: , groundwork for additional collaboration between the U.S. DOE its national laboratories (including Fermilab) and the UK Science and Technology Facilities Council, Neutrinos, UK labs and universities were important partners in the main Tevatron experiments CDF and DZero, UK Minister of State for Universities Science Research and Innovation Jo Johnson, UK science   

    From FNAL: “UK science minister announces $88 million for LBNF/DUNE, visits Fermilab” 

    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.

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    Jo Johnson learns about accelerator technologies at Fermilab. From left: Fermilab Chief Strategic Partnerships Officer Alison Markovitz; Fermilab scientist Anna Grassellino; Andrew Price of the UK Science and Innovation Network; DUNE co-spokesperson Mark Thomson; STFC Chief Executive Brian Bowsher; UK Minister of State for Universities, Science, Research and Innovation Jo Johnson. Photo: Reidar Hahn

    UK minister Jo Johnson traveled to the United States this week to sign the first ever umbrella science and technology agreement between the two nations and to announce approximately $88 million in funding for the international Long-Baseline Neutrino Facility and 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

    On Thursday, he visited the host laboratory for LBNF/DUNE, the U.S. Department of Energy’s Fermi National Accelerator Laboratory, emphasizing the importance of the project and the strong scientific partnership between the two countries.

    Johnson, the UK minister of state for universities, science, research and innovation, signed the agreement on Wednesday in Washington, D.C. Signing for the United States was Judith G. Garber, acting assistant secretary of state for oceans and international environmental and scientific affairs.

    This new agreement lays the groundwork for additional collaboration between the U.S. DOE, its national laboratories (including Fermilab) and the UK Science and Technology Facilities Council. STFC funds research in particle physics, nuclear physics, space science and astronomy in the United Kingdom. The U.S. DOE is the largest supporter of basic research in the physical sciences in the United States.

    “Our continued collaboration with the U.S. on science and innovation benefits both nations,” said Johnson, “and this agreement will enable us to share our expertise to enhance our understanding of many important topics that have the potential to be world changing.”

    LBNF/DUNE will be a world-leading international neutrino experiment based in the United States. Fermilab’s powerful particle accelerators will create the world’s most intense beam of neutrinos and send it 800 miles through Earth to massive particle detectors, which will be built a mile underground at the Sanford Underground Research Facility in South Dakota.

    The UK research community is already a major contributor to the DUNE collaboration, providing expertise and components to the facility and the experiment. UK contributions range from the high-power neutrino production target to the data acquisition systems to the software that reconstructs particle interactions into visible 3-D readouts.

    DUNE will be the first large-scale experiment hosted in the United States that runs as a truly international project, with more than 1,000 scientists and engineers from 31 countries building and operating the facility. Its goal is to learn more about ghostly particles called neutrinos, which may provide insight into why we live in a matter-dominated universe that survived the Big Bang.

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    The UK delegation visits the Fermilab underground neutrino experimental area. UK Minister Jo Johnson stands in the center. Immediately to his left is Fermilab Director Nigel Lockyer. Photo: Reidar Hahn

    In addition to Johnson, the UK delegation to Fermilab included Brian Bowsher, chief executive of STFC; Andrew Price of the UK Science and Innovation Network; and Martin Whalley, deputy consul general from the Great Britain Consulate in Chicago.

    They toured several areas of the lab, including the underground cavern that houses the NOvA neutrino detector, and the Cryomodule Test Facility, where components of the accelerator that will power DUNE are being tested. The UK will contribute world-leading expertise in particle accelerators to the upgrade of Fermilab’s neutrino beam and accelerator complex.

    “This investment is part of a long history of UK research collaboration with the U.S.,” said Bowsher. “International partnerships are the key to building these world-leading experiments, and I am looking forward to seeing our scientists work with our colleagues in the U.S. in developing this experiment and the exciting science that will happen as a result.”

    UK institutions have been a vital part of Fermilab’s 50-year history, from the earliest days of the laboratory. UK labs and universities were important partners in the main Tevatron experiments, CDF and DZero, in the 1980s and 1990s. UK institutions have been involved with accelerator research and development, are partners in Fermilab’s muon experiments and are at the forefront of Fermilab’s focus on neutrino physics.

    Sixteen UK institutions (14 universities and two STFC-funded labs) are contributors to the DUNE collaboration, the U.S.-hosted centerpiece for a world-class neutrino experiment. The collaboration is led by Mark Thomson, professor of experimental particle physics at the University of Cambridge, and Ed Blucher, professor and chair of the Department of Physics at the University of Chicago.

    “Our colleagues in the United Kingdom have been critical partners for Fermilab, for LBNF/DUNE and for the advancement of particle physics around the world,” said Fermilab Director Nigel Lockyer. “We look forward to the discoveries that these projects will bring.”

    See the full article here.

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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. 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 10:28 am on September 18, 2017 Permalink | Reply
    Tags: Alex Himmel of Fermilab, , , Chao Zhang of BNL, Congratulations to two award-winning DUNE collaborators, , , Neutrinos,   

    From NUS TO SURF: “Congratulations to two award-winning DUNE collaborators” 

    NUS TO SURF

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    “It is great news that the US DOE has recognized the talents of two early career DUNE scientists — both Alex and Chao have made invaluable contributions to DUNE and are both deserving recipients of these prestigious funding awards.”
    — DUNE spokespersons Mark Thomson and Ed Blucher

    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

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    Chao Zhang of BNL. Credit: BNL

    Exerpted and adapted from Three Brookhaven Lab Scientists Selected to Receive Early Career Research Program Funding, BNL Newsroom, 15 Aug 2017.

    Brookhaven Lab physicist and DUNE collaborator Chao Zhang was selected by DOE’s Office of High Energy Physics to receive funding for a project titled Optimization of Liquid Argon TPCs for Nucleon Decay and Neutrino Physics. Liquid Argon TPCs form the heart of many large-scale particle detectors designed to explore fundamental mysteries in particle physics.

    Chao’s aim is to optimize the performance of the DUNE far detector LArTPCs to fully realize their potential to track and identify particles in three dimensions, with a particular focus on making them sensitive to rare proton decays.

    His team at Brookhaven Lab will establish a hardware calibration system to ensure the experiment’s ability to extract subtle signals using specially designed cold electronics that will sit within the detector. They will also develop software to reconstruct the three-dimensional details of complex events, and analyze data collected at a prototype experiment (ProtoDUNE, located at Europe’s CERN laboratory) to verify that these methods are working, before incorporating any needed adjustments into the design of the detectors for DUNE.

    “I am honored and thrilled to receive this distinguished award,” said Chao. “With this support, my colleagues and I will be able to develop many new techniques to enhance the performance of LArTPCs, and we are excited to be involved in the search for answers to one of the most intriguing mysteries in science, the matter-antimatter asymmetry in the universe.”

    Read full article.


    Alex Himmel of Fermilab. Credit: Fermilab

    This article is excerpted and adapted from a Fermilab news article, 14 September 2017.

    Fermilab’s Alex Himmel expects to spend a large chunk of his career working on the Deep Underground Neutrino Experiment (DUNE), the flagship experiment of the U.S. particle physics community. That is incentive, he says, to lay the groundwork now to ensure its success.

    The Department of Energy has selected Himmel, a Wilson fellow, for a 2017 DOE Early Career Research Award to do just that. He will receive $2.5 million over five years to build a team and optimize software that will measure the flashes of ultraviolet light generated in neutrino collisions in a way that will determine the energy of the neutrino more precisely than is currently possible.

    Photons released from neutrino collisions will arrive at their detectors deteriorated and distorted due to scattering and reflections; the light measured is not the same as what was given off.

    “What we want to know is, given an amount of energy deposited in the argon, how much light do we see, taking out all the other things we know about how the light moves inside the detector,” he explained.

    Researchers are already looking forward to the long-term, positive impact of Himmel’s research.

    “Alex has been a true leader in understanding the physics potential of scintillation light in liquid-argon detectors,” said Ed Blucher. “His plan to develop techniques to make the most effective use of photon detection will help to enable the best and broadest possible physics program for DUNE.”

    Himmel has deep ties with Fermilab and neutrinos, starting with his first job as a summer student at Fermilab when he was 16. In 2012, he won the Universities Research Association Thesis Award for his research on muon antineutrino oscillations at Fermilab’s MINOS experiment.

    Read full article.

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  • richardmitnick 9:10 am on September 18, 2017 Permalink | Reply
    Tags: , , Neutrinos, , ,   

    From Stanford: “What ‘Ghost Particles’ Might Tell Us About Our Origins” EXO-200 Experiment 

    Stanford University Name
    Stanford University

    9.18.17
    Daisy Yuhas

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    Stanford physicists hope an elusive subatomic particle will help us answer big questions, such as ‘Why is our universe dominated by matter?’

    SLAC EXO-200 Enriched Xenon Observatory near Carlsbad, New Mexico

    SLAC EXO-200 Enriched Xenon Observatory near Carlsbad, New Mexico

    SLAC EXO-200 Enriched Xenon Observatory near Carlsbad, New Mexico

    The stars were still faintly visible on the morning four years ago that Scott Kravitz first drove out to the salt mines in southeastern New Mexico. Then a second-year graduate student in physics, Kravitz was preparing to journey half a mile below the Earth’s surface.

    When he arrived at the facility, Kravitz passed through security, donned coveralls and safety equipment (including a portable air purifier in case of fire), and boarded a mesh-walled container called the cage. The double-decker structure — which fits no more than six people on each level — is the only method for descending to the tunnels below.

    It was unlike any elevator Kravitz had ridden. Within seconds, he and his fellow passengers were swallowed by darkness. No one spoke. No one turned on a headlamp. The soft sounds of air whistling past and the rattling of the cage were all he could hear.

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    “It was like a meditation,” Kravitz recalls. The trip felt longer than its five-minute duration. Kravitz was eager to disembark, but not out of nervousness. More than anything, he was excited about what lay below.

    When the doors opened, a wave of hot, stale air thick with salt dust greeted him. Headlamps and overhead lighting illuminated the excavated rose-gray walls and floor of the 250-million-year-old mineral reserve.

    What brought Kravitz to this remote spot beneath the desert was neither geology nor earth science. Nor was it waste disposal — though the nearly impermeable salt bed is primarily used for that purpose, housing drums of radioactive refuse. Kravitz, PhD ’17, had come as a member of Stanford physics professor Giorgio Gratta’s research team, which studies elusive subatomic particles called neutrinos. Down in the mines, the scientists are trying to detect an unusual event that could unlock mysteries about the makeup of everything around us.

    Little Neutral Ones

    The neutrino is a fundamental (or indivisible) particle of matter, significantly smaller than an atom. It is just one of 17 fundamental particles that physicists have discovered to date. Others include the electron, familiar from high school chemistry class, and the photon, or particle of light, which is the only fundamental particle our eyes can detect.

    Each of these particles has special properties, and the neutrino is no exception. For one, it is the most abundant particle of matter. Its name comes from the Italian for “little neutral one,” encapsulating both the fact that it is very tiny — even for a fundamental particle — and that it has no positive or negative electric charge.

    “Neutrinos are the particles that we understand the least,” says theoretical physicist André de Gouvêa. “And they are important for understanding a lot of natural phenomena.” A professor at Northwestern University, de Gouvêa has spent much of his career studying neutrinos and developing models to explain how they fit into our understanding of the rest of the universe.

    Neutrinos are born when the nucleus of an atom changes in some way. That change could come about when atoms in a radioactive material break down. But it could also happen when atomic nuclei join together (fusion) or split apart (fission), two of the most energetically intense events known to humankind.

    In a trailer-like clean room in the depths of the mine, Gratta’s team monitors the breakdown of a radioactive form of the element xenon. Radioactive material is inherently unstable. As the xenon decays, the nuclei within its atoms may release other particles. Gratta and others want to see whether neutrinos emerge and then annihilate each other.

    Certain theories predict such a find. But if the interaction exists, it will be tough to spot. “You are dealing with very rare processes,” Gratta explains.

    The salt mines offer an ideal location for their project. On Earth’s surface, we are constantly bombarded by subatomic particles that would be difficult to disentangle from an experiment’s data set. Deep underground, the layers of salt and earth create a shield that blocks most unwanted phenomena from the scientists’ detector.

    At the moment, the experiment — called EXO-200 — is in a race, of sorts, with several other particle physics experiments that have the same end goal.

    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

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    _________________________________________________________________________________________________
    About EXO-200…
    The Enriched Xenon Observatory is an experiment in particle physics aiming to detect “neutrino-less double beta decay” using large amounts of xenon isotopically enriched in the isotope 136. A 200-kg detector using liquid Xe is currently being installed at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. Many research and development efforts are underway for a ton-scale experiment, with the goal of probing new physics and the mass of the neutrino.

    Our Collaboration:

    University of Alabama
    Universität Bern
    Caltech
    Carleton University
    Colorado State University
    Drexel University
    Duke University
    IHEP
    Indiana University
    UC Irvine
    Institute of Basic Science (Republic of Korea)
    ITEP (Moscow)
    Laurentian University
    McGill University
    University of Erlangen-Nuremberg
    University of Illinois at Urbana-Champaign
    University of Maryland
    University of Massachusetts – Amherst
    University of North Carolina Wilmington
    University of South Dakota
    SLAC National Accelerator Laboraotory
    Stanford University
    Stony Brook University
    Technische Universität München
    TRIUMF
    Yale University

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    Neutrinoless Double Beta Decay

    Neutrinoless double beta decay is a special case of beta decay. Beta decay is a common form of nuclear decay which occurs when a neutron in an unstable nucleus emits an electron and an antineutrino and becomes a proton.

    Double beta decay occurs when a nucleus is energetically or spin forbidden to decay through single beta decay. While it has been predicted to exist for a long time, the long half-life makes it difficult to observe. Double beta decay was only first observed in 1986. Many isotopes undergo double beta decay, including xenon 136. EXO-200 was the first experiment to observe this decay in xenon. In normal double beta decay, two electrons and two antineutrinos are ejected from the nucleus when two neutrons become protons. The half-lives of double beta decay isotopes are very long, above 1020 years. This is more than a billion times longer than the age of the universe! So if you started with 8 billion atoms that can undergo double beta decay at the beginning of the universe, you would expect about 1 to have decayed by now. 0nbb

    Neutrinoless double beta decay has not yet been seen, but some theories predict it. It is like normal double beta decay, but because of special properties of the neutrino, no neutrinos would be emitted from the nucleus. The electrons would carry all the energy of the decay, unlike normal double beta decay, in which the antineutrinos carry away energy. Thus, neutrinoless double beta decay has a unique, observable signature. In order for this to occur, the neutrino would have to be its own antiparticle. If neutrinos are their own antiparticles, which are known as “Majorana” particles, then this admits many elegant theories to explain how neutrinos acquire mass and why their mass is so much smaller than any other particle we know.

    We want to see neutrinoless double beta decay for two reasons. First, we don’t know if the neutrino is its own antiparticle or not, and seeing it would answer this question for sure. Second, we don’t know the exact mass of the neutrino and a measurement of the neutrinoless double beta decay half life would allow us to measure the neutrino mass. Even if we don’t see neutrinoless double beta decay, a limit on the half life places a limit on the neutrino mass.

    If you’re still curious, Physics World has a nice article on neutrinoless double beta decay that is more detailed, but still accessible to a lay person.

    EXO-200
    EXO-200 is a prototype to develop techniques for working with liquid xenon in a time projection chamber (TPC). One possibility for tonne-scale EXO is a liquid TPC, so familiarity with EXO-200 technologies will contribute to the design of tonne-scale EXO. Additionally, EXO-200 provides a testing ground for developing and procuring extremely radiopure materials and removing backgrounds. EXO-200 has provided fundamental measurement of the double beta decay of xenon 136 and will provide improved limits on the rate of (or perhaps observation of) neutrinoless double beta decay.

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    We are using 200 kg of liquid xenon (LXe) enriched to 80% of the 136 isotope for EXO-200. The LXe fills our TPC vessel. When a particle deposits energy in the liquid xenon, it ionizes the xenon atoms, knocking electrons off. We apply an electric field to the xenon, which pushes many of the electrons to wire grids where they are collected. The grid position provides a 2D location, and the number of electrons is related to the event’s energy. But some xenon ions recombine with the electrons before they can drift away. This puts the xenon atoms into excited states. When the excited atoms relax, they release ultraviolet light, known as scintillation, which we collect on avalanche photodiodes (APDs). The time between the light signal (which comes nearly instantaneously) and the ionization signal (which must drift and takes microsecond to arrive) allows us to reconstruct the full 3D location of the event when combined with the 2D position from the wire grids. Furthermore, the amount of light is also related to the event’s energy. Combining the ionization and light signals allows a better energy measurement than using either signal on its own.

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    The TPC vessel is contained within a cryostat system to help keep the xenon at liquid temperature. The vessel is contained in a volume of HFE-7000, a synthetic fluid that is liquid from room temperature down to LXe temperatures. The HFE is within a large copper cryostat, which is then inside another coper cryostat with a vacuum gap in between for insulation. The cryostat is shielded with lead and contained in a class-100 cleanroom located 2150 ft underground at the Department of Energy’s Waste Isolation Pilot Plant. All of this is necessary to shield from radioactive backgrounds and cosmic rays. On top of that, materials contained within the lead have been extensively counted for radiopurity. The materials are low in radioactive isotopes and contamination. The majority of the material is ultrapur, copper, teflon, phosphorbronze, and acrylic.
    __________________________________________________________________________________________________

    The stakes for their search are high. If neutrinos truly can cancel each other out, they could be the key to explaining one of the mysteries of how we came to be. Physicists recognize that when two particles of equal mass but opposite charge meet, they can collide and leave nothing but energy behind. When such an event occurs, it means that one particle was the other’s antiparticle. Antiparticles together make antimatter, and the existence of antimatter raises some uncomfortable questions. Nearly all particles of matter have antimatter counterparts, and because nature tends to favor balance, many scientists suspect that matter and antimatter were created equally at the dawn of time. But if that were the case, one might expect the two would simply destroy each other. Instead, we exist in a universe dominated by matter.

    If neutrinos can behave as their own antiparticles, that could help scientists decipher how matter particles came to outnumber their antimatter counterparts. Thus far, the search has come up empty. But the EXO-200 team is not discouraged. Regardless of whether they see this strange antimatter process, Gratta, Kravitz and their colleagues have already begun providing insight into an enigmatic particle. “Neutrinos have a number of peculiarities,” Gratta says. They have surprised scientists many times before and are bound to surprise them again.

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    WHAT’S INSIDE: The EXO-200 experiment’s detector is composed of two parts — a central copper drum (bottom), which will be filled with xenon, and a large cooling system to keep the element in its liquid form. The detector enables Gratta and his team to study neutrinos. (Photos: Courtesy the EXO-200 Collaboration)

    Shape-shifters

    Every second, trillions of neutrinos pass through you, but over a lifetime, only one or two may actually hit another particle in your body. They are small enough that they rarely bump into other particles, and because of their neutrality, they do not respond to the forces of electricity and magnetism. As a result, they can travel uninterrupted for long distances, and they are extremely difficult to catch. Stanford emeritus professor of physics Stan Wojcicki, another neutrino aficionado, explains that these particles have other curious properties. For example, the neutrino can come in any one of three types, or “flavors,” called electron, muon and tau. “As they travel across the atmosphere, they morph into another flavor,” Wojcicki says. From the late ’90s into the 2000s, Wojcicki studied those transformations.

    Shape-shifting is not unheard of among fundamental particles, but it was unexpected in neutrinos. Such changes are possible only through a quantum mechanical process that requires the particles involved to have mass. Yet, “the current theory of particle physics as a whole predicts that the mass of the neutrino should be zero,” de Gouvêa says. If scientists knew the precise mass, theoretical physicists could rework the existing models to build new, more comprehensive theories.

    The EXO-200 experiment could be well-positioned to resolve that quandary. If scientists succeed in their quest to see neutrinos behave as their own antimatter particles, Gratta explains, they will be “automatically measuring the mass of the particles involved.” That’s because physicists have worked out a relationship between the rate at which materials decay and the mass of the neutrinos present. Heavier neutrinos, for example, would be involved in more frequent decays than lighter neutrinos.

    More broadly, the EXO-200 experiment is testing two competing theories from the early 20th century about the nature of neutrinos. In one, proposed by a theoretical physicist named Paul Dirac, all particles can appear in one of four states that relate to their charge and how they move. But because neutrinos are neutral, another theorist, Ettore Majorana, suggested that each neutrino type might have just two variants. If so, he predicted that the two variants would have opposite qualities and therefore the same particle could cancel itself out — implying that the neutrino is its own antiparticle. (In July, physicists at Stanford and UC-Irvine demonstrated that they could create situations in which particle-like bundles of energy behave as both particle and antiparticle, adding extra heft to Majorana’s ideas.) “So, that’s what we’re after,” Gratta says. “We’re trying to detect whether neutrinos are Majorana particles.”

    Questions about the mass and variety of neutrinos are not merely academic. By better understanding their traits and behavior, scientists can also advance the study of the phenomena that produce them. Neutrinos from the sun, for example, are the product of fiery processes happening at that star’s core; by detecting those neutrinos, scientists have proof of a reaction they cannot otherwise observe (see sidebar, “Where Do Neutrinos Come From?”).

    Ghosts in the Machine

    Tucked within a corner of the salt mine, far from the waste storage, are metal containers set up by EXO-200 physicists to house their bright white, ultrasterilized “clean room.” The contrast between dark, gritty tunnel and hospital-esque experimental space is stark.

    As soon as they arrive, the scientists crowd into the clean room, three at a time, to change from miner gear into special Tyvek coveralls called bunny suits. This uniform prevents dirt, oil, hair and other detritus from dirtying their instruments. A large lead wall between the physicists and the detector itself forms an added radiation barrier. Without it, even a scientist’s sack lunch could significantly alter the detector’s readings.

    The EXO-200 detector was assembled at Stanford and moved into the mines in 2007, thanks to a collaborative effort among scientists that now spans 25 institutions in seven countries. EXO is an acronym for Enriched Xenon Observatory, and at its heart is a 200-kilogram (440-pound) tank filled with xenon. Radioactive xenon decays so slowly that the detector may only pick up data from a few events each year. To boost these numbers, the xenon is “enriched” to increase the odds of observing interesting decays. That means the scientists remove isotopes they won’t need while preserving the ones they expect to produce a neutrinoless decay.

    The task of neutrino hunting has been all about probability from the start. In 1930, the Austrian theoretical physicist Wolfgang Pauli first proposed the neutrino’s existence. At the time, he and his colleagues were puzzled. Several experiments had shown that radioactive elements decay and release electrons with much less energy than expected, given the materials involved. That finding might be explained, Pauli suggested, if another particle — incredibly small and without any charge — was also emerging from the decay.

    He figured the odds were so slim that anyone would be able to find this tiny neutral particle that he bet a case of Champagne against it. He is said to have remarked: “I have committed the cardinal sin of a theorist. I made a prediction which can never be tested.”

    Nonetheless, in the 1950s, American physicists Fred Reines and Clyde Cowan, based at the Los Alamos laboratory in New Mexico, took up the challenge. In honor of the strange ghostlike ability of their quarry, they named the experiment Project Poltergeist.

    Reines and Cowan built a giant detector for its time, 1 cubic meter in size. Because the neutrino only rarely touches other particles, the reasoning went — and still goes — that physicists need to monitor a very large amount of material for a very long time to increase the likelihood of spotting a neutrino in action. In 1956, Reines and Cowan confirmed that they had seen a neutrino interact with protons in tanks of cadmium chloride.

    Typically, “a neutrino comes into a detector and most of the time you don’t see it,” Stan Wojcicki says. “But very, very seldom, it will satisfy your curiosity and interact.” When that happens, depending on the materials involved, light, heat or even sound can be produced and measured.

    Researchers have built many kinds of neutrino detectors in the past half century — uncovering, in the process, the three flavors and the fact that neutrinos transform from one form into another. Today, there are essentially two types of detector. One catches particles that journey into the experiment from disparate sources, such as stars and power plants. Scientists on the Super-Kamiokande experiment in Japan, for example, observe neutrinos from the sun and atmosphere as they interact with particles within a detector that contains 50,000 tons of water and is situated beneath a mountain.

    The other class of detectors, which includes EXO-200, references the experiments that first inspired Pauli; they produce neutrinos within the detector using radioactive material and then measure the energy of particles such as electrons created during the decay. Using that information, the EXO-200 team can then determine whether neutrinos are present — or, as many hope, absent. Seeing a neutrinoless decay would indicate “a totally new process,” says Kravitz. “It implies that there are other particles out there that we don’t know about.”

    The Next Generation

    To date, there is still no confirmation that neutrinos serve as their own antiparticles. But Gratta’s team has made some interesting finds. In 2011, the researchers observed a rare pattern of decay in which a nucleus from an atom of xenon broke down to release two electrons and two neutrinos. The discovery is evidence of one of the slowest decay processes ever studied; it would ultimately take sextillions of years for their total sample to break down in this manner, longer than our universe has existed to date.

    In addition, the researchers have advanced the quest to ascertain the neutrino’s mass. Based on the languid rates of decay they have seen, the EXO-200 physicists can conclude that the neutrino is at least 3.5 million times lighter than an electron.

    To learn more, the scientists say it’s time for a new detector. EXO-200 will only continue to collect data for another year and a half, at which point the researchers believe they will have learned as much as they’re able to with that equipment. The proposed successor, dubbed NEXO, would contain a tank 25 times larger than the one in EXO-200’s detector. Able to accommodate about five tons of liquid xenon, NEXO would give the researchers significantly more decay data to study, accelerating the rate at which they can learn about these particles and enabling them to capitalize on what they’ve learned so far.

    In the meantime, the physicists have gained a certain fondness for their salt mine. “In many ways, it’s much more pleasant than other mines that I’ve been to,” Gratta says. Whereas some sites leave scientists mired in mud, he notes, “salt is very healthy.”

    Admittedly, it presents its challenges. When asked to provide a photograph from the tunnels, Gratta explains that salt dust and flash photography don’t mix — the images are speckled with bright white dots. “They look like stars,” he observes. The visual is a curious reminder of all the motes and particles we otherwise never see.

    “We were the first of these experiments to turn on,” Gratta says. “And hopefully, by this summer, we will be ahead.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:51 pm on September 13, 2017 Permalink | Reply
    Tags: , , Neutrinos,   

    From FNAL: “Contract awarded for LBNF preconstruction services” 

    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.

    September 13, 2017
    Leah Poffenberger

    On July 21, a group of dignitaries broke ground on the Long-Baseline Neutrino Facility (LBNF) 4,850 feet underground in a former goldmine, making a small dent in the 875,000 tons of rock that will ultimately be excavated for Fermilab’s flagship 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

    But a groundbreaking ceremony doesn’t always mean you can get straight to digging.

    Removing 875,000 tons of rock from a mile underground and assembling a massive particle detector in its place is a big job. Many months of careful design and preparatory construction work have to happen before the main excavation can even start at the future site of the Deep Underground Neutrino Experiment (DUNE) at Sanford Underground Research Facility in Lead, South Dakota.

    On Aug. 9, a new team officially signed on to help prepare for the excavation and construction of DUNE. Fermi Research Alliance LLC, which operates Fermilab, awarded Kiewit/Alberici Joint Venture (KAJV) a contract to begin laying the groundwork for the excavation for LBNF, the facility that will support DUNE.

    “Our team is excited and honored to serve as the construction manager/general contractor on a project like the Long-Baseline Neutrino Facility,” said KAJV Project Manager Scott Lundgren. “We look forward to working with Fermi Research Alliance to support this groundbreaking physics experiment.”

    Under the contract, over the next 12 months, KAJV will assist in the final design and excavation planning for LBNF/DUNE.

    “We’re all very excited about this partnership,” said Troy Lark, LBNF procurement manager. “It’s great to be working with two premier international contracting companies on this project.”

    The four-story-high, 70,000-ton DUNE detector at LBNF will catch neutrinos — subatomic particles that rarely interact with matter — sent through the Earth’s mantle from Fermilab, 800 miles away. This international megascience experiment will work to unravel some of the mysteries surrounding neutrinos, possibly leading to a better understanding of how the universe began.

    Building such an ambitious experiment has some unique challenges.

    “It’s kind of like building a ship in a bottle,” said Chris Mossey, Fermilab’s deputy director for LBNF. “We’re using a narrow shaft to move all the excavated rock up, and then all the parts and pieces of very large cryostats and detectors down to the 4850 level, about a mile underground.”

    KAJV will have two main tasks. The first is to help finalize design and excavation plans for LBNF. The second is to use the finalized designs to create what are known as bid packages: specific projects that KAJV or other contractors will work on.

    These bid packages will include jobs such as building site infrastructure and ensuring the structural integrity of the building above the shaft through which everything will enter or exit the mine.

    “Before you excavate 875,000 tons of rock, there’s a lot of things you’ve got to do. You have to have a system to move the rock safely from where it’s excavated to the surface, then horizontally about 3,700 feet to the large open pit where it will be deposited,” Mossey said. “All that has to be built.”

    Construction on pre-excavation projects — such as the conveyor system to move the rock — is expected to begin in 2018. The main excavation for LBNF/DUNE is planned to start in 2019.

    “We’re really happy to get this contract awarded,” Mossey said. “It was a lot of work to get to this point — a lot by the project, the lab and the DOE team. Everybody worked to be able to get this big, complicated contract in place.”

    See the full article here .

    Please help promote STEM in your local schools.

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    FNAL Icon
    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 9:55 pm on September 5, 2017 Permalink | Reply
    Tags: , , , , , , , , , Neutrinos, , , ,   

    From Symmetry: “What can particles tell us about the cosmos?” 

    Symmetry Mag
    Symmetry

    09/05/17
    Amanda Solliday

    The minuscule and the immense can reveal quite a bit about each other.

    In particle physics, scientists study the properties of the smallest bits of matter and how they interact. Another branch of physics—astrophysics—creates and tests theories about what’s happening across our vast universe.

    1
    The current theoretical framework that describes elementary particles and their forces, known as the Standard Model, is based on experiments that started in 1897 with the discovery of the electron. Today, we know that there are six leptons, six quarks, four force carriers and a Higgs boson. Scientists all over the world predicted the existence of these particles and then carried out the experiments that led to their discoveries. Learn all about the who, what, where and when of the discoveries that led to a better understanding of the foundations of our universe.

    While particle physics and astrophysics appear to focus on opposite ends of a spectrum, scientists in the two fields actually depend on one another. Several current lines of inquiry link the very large to the very small.

    The seeds of cosmic structure

    For one, particle physicists and astrophysicists both ask questions about the growth of the early universe.

    In her office at Stanford University, Eva Silverstein explains her work parsing the mathematical details of the fastest period of that growth, called cosmic inflation.

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    “To me, the subject is particularly interesting because you can understand the origin of structure in the universe,” says Silverstein, a professor of physics at Stanford and the Kavli Institute for Particle Astrophysics and Cosmology. “This paradigm known as inflation accounts for the origin of structure in the most simple and beautiful way a physicist can imagine.”

    Scientists think that after the Big Bang, the universe cooled, and particles began to combine into hydrogen atoms. This process released previously trapped photons—elementary particles of light.

    The glow from that light, called the cosmic microwave background, lingers in the sky today.

    CMB per ESA/Planck

    Scientists measure different characteristics of the cosmic microwave background to learn more about what happened in those first moments after the Big Bang.

    According to scientists’ models, a pattern that first formed on the subatomic level eventually became the underpinning of the structure of the entire universe. Places that were dense with subatomic particles—or even just virtual fluctuations of subatomic particles—attracted more and more matter. As the universe grew, these areas of density became the locations where galaxies and galaxy clusters formed. The very small grew up to be the very large.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    Dark Matter

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LUX Dark matter Experiment at SURF, Lead, SD, USA

    ADMX Axion Dark Matter Experiment, U Uashington

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    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

    “It’s amazing that we can probe what was going on almost 14 billion years ago,” Silverstein says. “We can’t learn everything that was going on, but we can still learn an incredible amount about the contents and interactions.”

    For many scientists, “the urge to trace the history of the universe back to its beginnings is irresistible,” wrote theoretical physicist Stephen Weinberg in his 1977 book The First Three Minutes. The Nobel laureate added, “From the start of modern science in the sixteenth and seventeenth centuries, physicists and astronomers have returned again and again to the problem of the origin of the universe.”

    Searching in the dark

    Particle physicists and astrophysicists both think about dark matter and dark energy. Astrophysicists want to know what made up the early universe and what makes up our universe today. Particle physicists want to know whether there are undiscovered particles and forces out there for the finding.

    “Dark matter makes up most of the matter in the universe, yet no known particles in the Standard Model [of particle physics] have the properties that it should possess,” says Michael Peskin, a professor of theoretical physics at SLAC.

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

    “Dark matter should be very weakly interacting, heavy or slow-moving, and stable over the lifetime of the universe.”

    There is strong evidence for dark matter through its gravitational effects on ordinary matter in galaxies and clusters. These observations indicate that the universe is made up of roughly 5 percent normal matter, 25 percent dark matter and 70 percent dark energy. But to date, scientists have not directly observed dark energy or dark matter.

    “This is really the biggest embarrassment for particle physics,” Peskin says. “However much atomic matter we see in the universe, there’s five times more dark matter, and we have no idea what it is.”

    But scientists have powerful tools to try to understand some of these unknowns. Over the past several years, the number of models of dark matter has been expanding, along with the number of ways to detect it, says Tom Rizzo, a senior scientist at SLAC and head of the theory group.

    Some experiments search for direct evidence of a dark matter particle colliding with a matter particle in a detector. Others look for indirect evidence of dark matter particles interfering in other processes or hiding in the cosmic microwave background. If dark matter has the right properties, scientists could potentially create it in a particle accelerator such as the Large Hadron Collider.

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    Physicists are also actively hunting for signs of dark energy. It is possible to measure the properties of dark energy by observing the motion of clusters of galaxies at the largest distances that we can see in the universe.

    “Every time that we learn a new technique to observe the universe, we typically get lots of surprises,” says Marcelle Soares-Santos, a Brandeis University professor and a researcher on the Dark Energy Survey. “And we can capitalize on these new ways of observing the universe to learn more about cosmology and other sides of physics.”

    Forces at play

    Particle physicists and astrophysicists find their interests also align in the study of gravity. For particle physicists, gravity is the one basic force of nature that the Standard Model does not quite explain. Astrophysicists want to understand the important role gravity played and continues to play in the formation of the universe.

    In the Standard Model, each force has what’s called a force-carrier particle or a boson. Electromagnetism has photons. The strong force has gluons. The weak force has W and Z bosons. When particles interact through a force, they exchange these force-carriers, transferring small amounts of information called quanta, which scientists describe through quantum mechanics.

    General relativity explains how the gravitational force works on large scales: Earth pulls on our own bodies, and planetary objects pull on each other. But it is not understood how gravity is transmitted by quantum particles.

    Discovering a subatomic force-carrier particle for gravity would help explain how gravity works on small scales and inform a quantum theory of gravity that would connect general relativity and quantum mechanics.

    Compared to the other fundamental forces, gravity interacts with matter very weakly, but the strength of the interaction quickly becomes larger with higher energies. Theorists predict that at high enough energies, such as those seen in the early universe, quantum gravity effects are as strong as the other forces. Gravity played an essential role in transferring the small-scale pattern of the cosmic microwave background into the large-scale pattern of our universe today.

    “Another way that these effects can become important for gravity is if there’s some process that lasts a long time,” Silverstein says. “Even if the energies aren’t as high as they would need to be sensitive to effects like quantum gravity instantaneously.”

    Physicists are modeling gravity over lengthy time scales in an effort to reveal these effects.

    Our understanding of gravity is also key in the search for dark matter. Some scientists think that dark matter does not actually exist; they say the evidence we’ve found so far is actually just a sign that we don’t fully understand the force of gravity.

    Big ideas, tiny details

    Learning more about gravity could tell us about the dark universe, which could also reveal new insight into how structure in the universe first formed.

    Scientists are trying to “close the loop” between particle physics and the early universe, Peskin says. As scientists probe space and go back further in time, they can learn more about the rules that govern physics at high energies, which also tells us something about the smallest components of our world.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 7:58 am on August 10, 2017 Permalink | Reply
    Tags: , , Neutrinos, , , ,   

    From ScienceNews: “Neutrino experiment may hint at why matter rules the universe” 

    ScienceNews bloc

    ScienceNews

    1
    NEUTRINO CLUES The T2K experiment found clues that neutrinos may behave differently than their antimatter partners. In a possible sighting of an electron neutrino at the Super-Kamiokande detector in Hida, Japan (shown), colored spots represent sensors that observed light from the interacting neutrino. Kamioka Observatory/ICRR/The University of Tokyo

    A new study hints that neutrinos might behave differently than their antimatter counterparts. The result amplifies scientists’ suspicions that the lightweight elementary particles could help explain why the universe has much more matter than antimatter.

    In the Big Bang, 13.8 billion years ago, matter and antimatter were created in equal amounts. To tip that balance to the universe’s current, matter-dominated state, matter and antimatter must behave differently, a concept known as CP, or “charge parity,” violation.

    In neutrinos, which come in three types — electron, muon and tau — CP violation can be measured by observing how neutrinos oscillate, or change from one type to another. Researchers with the T2K experiment found that muon neutrinos morphed into electron neutrinos more often than expected, while muon antineutrinos became electron antineutrinos less often. That suggests that the neutrinos were violating CP, the researchers concluded August 4 at a colloquium at the High Energy Accelerator Research Organization, KEK, in Tsukuba, Japan.

    T2K scientists had previously presented a weaker hint [Physical Review Letters]of CP violation. The new result is based on about twice as much data, but the evidence is still not definitive. In physicist parlance, it is a “two sigma” measurement, an indicator of how statistically strong the evidence is. Physicists usually require five sigma to claim a discovery.

    Even three sigma is still far away — T2K could reach that milestone by 2026. A future experiment, DUNE, now under construction at the Sanford Underground Research Laboratory in Lead, S.D., may reach five sigma.

    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

    It is worth being patient, says physicist Chang Kee Jung of Stony Brook University in New York, who is a member of the T2K collaboration. “We are dealing with really profound problems.”

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

    Published since 1922, the biweekly print publication reaches about 90,000 dedicated subscribers and is available via the Science News app on Android, Apple and Kindle Fire devices. Updated continuously online, the Science News website attracted over 12 million unique online viewers in 2016.

    Science News is published by the Society for Science & the Public, a nonprofit 501(c) (3) organization dedicated to the public engagement in scientific research and education.

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  • richardmitnick 11:02 am on August 7, 2017 Permalink | Reply
    Tags: , , , , , Neutrinos,   

    From BNL: “MicroBooNE Produces Clearest Images of Neutrino Interactions Yet” 

    Brookhaven Lab

    August 7, 2017
    Kelsey Harper
    kharper@bnl.gov

    With updates to its electronics, the state-of-the-art neutrino detector now boasts impressive “signal to noise” sensitivity.

    1
    A 3D reconstruction of various particles, including neutrinos, interacting with the argon atoms inside MicroBooNE’s time projection chamber (TPC). This reconstruction is based off of when and where electrons produced by such interactions hit the plane of wires at one end of the TPC.

    FNAL/MicrobooNE

    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab).

    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab). With implementation of sophisticated noise-filtering software and updates to the detector hardware, the MicroBooNE collaboration has produced new clean images that make it easier for researchers to spot and study different types of neutrinos. A paper published in the Journal of Instrumentation illustrates the electronic challenges and solutions that led to this advance.

    “These innovations will naturally be included in the next generation of neutrino detector design,” said Brookhaven physicist Xin Qian, the leader of Brookhaven’s MicroBooNE physics group.

    The next generation is a big deal, literally: four 17,000-ton neutrino detectors (compared to MicroBooNE’s “small” 170-ton detector) are planned for a future Deep Underground Neutrino Experiment (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

    This massive project will attempt to solve some of the biggest mysteries about neutrinos and their role in our universe.

    Tracking elusive particles

    Trillions of neutrinos—abundant yet elusive particles created in the nuclear reactions powering stars—stream from our sun to Earth every second. But because these particles so rarely interact with matter (which is why we don’t feel them passing through us), the detectors built to spot them must be extremely large and sensitive. To study neutrinos, scientists often also turn to more intense and easily understood sources of these particles: nuclear reactors and particle accelerators. The MicroBooNE collaboration studies neutrinos generated by the Booster proton accelerator at Fermilab, and collects detailed images of their interactions with a detector called a liquid-argon time projection chamber (LArTPC).

    3
    MicroBooNE’s time projection chamber—where the neutrino interactions take place—during assembly at Fermilab. The chamber measures ten meters long and two and a half meters high. Photo credit: Fermilab

    Although a ‘time projection chamber’ may sound like something from a Michael Crichton novel, it’s a very real technology that has transformed neutrino physics. It’s one of the few types of detectors that can see most of what happens when a neutrino interacts inside.

    Neutrinos come in three different “flavors”—electron, muon, and tau. As these neutrinos sail through the LArTPC’s school bus-sized tank of argon, kept liquid at a biting -303 degrees Fahrenheit, they occasionally interact with one of the argon atoms. This interaction produces charged and neutral particles, with a charged particle sometimes corresponding to the type of neutrino involved. The charged particles shoot through the bath, kicking electrons off the argon atoms they pass. These electrons get caught in the tank’s strong electric field and zip toward one end, eventually striking an array of wires. Based on the time and placement of each signal generated when an electron strikes a wire, scientists can figure out where the neutrino collision took place and what it looked like, allowing them to determine the type and energy of the neutrino detected.

    Trouble arises, however, when the little currents produced by the kicked-off electrons are muffled by electronic “noise.” Much like static on a radio, noise can drown out the signals of a neutrino collision, making the reconstructed paths blurry and difficult to analyze. According to Jyoti Joshi, a Brookhaven Lab post-doctoral fellow and the leader of the MicroBooNE detector physics working group, the challenge with LArTPC electronics is that “the signal we’re dealing with is so small that we need a very, very sensitive detector to amplify the signal so we can see it. But then, of course, you amplify anything, including noise.”

    4
    Brookhaven Lab physicist Hucheng Chen holding a replica of one of the 50 cold electronics boards installed in MicroBooNE. He is standing next to a mock-up of one of MicroBooNE’s 11 signal feedthroughs—the part of the detector where electronic signals from the cold electronics of the time projection chamber are carried to the warm electronics outside the cryostat.

    To try to minimize noise, MicroBooNE researchers worked with the engineers and scientists at Fermilab and in Brookhaven Lab’s Instrumentation Division who had pioneered the development of “cold electronics” for the experiment. Placing the electronics inside the detector tank reduces noise by shortening the path each signal has to travel before getting amplified. But because the tank is filled with liquid argon, these electronics had to be designed to thrive at temperatures hundreds of degrees below zero, long past the range where conventional electronics, like those in your smartphone, can function.

    The researchers expected the cold electronics installed at MicroBooNE to produce relatively clean signals and a good picture of the neutrino collisions. But “there are always some surprises,” said Mary Bishai, a senior physicist at Brookhaven Lab. “We had all this excess noise, and at the beginning people blamed the newest technology, the cold electronics.”

    After a year of collecting data, the researchers had enough information to pinpoint three sources of excess noise.

    “The noise was nearly all from the conventional electronics outside the argon tank,” said Mike Mooney, a Brookhaven Lab post-doctoral fellow and a key contributor in the effort to identify sources of noise.

    Most of the noise came from the external power supply for the electronics inside the bath, and from small fluctuations in the high voltage that creates the tank’s electric field. The third and least significant source of noise was an unusual burst that appeared only at a certain frequency, but the team has yet to determine where this final source comes from.

    The collaboration initially reduced the excess noise by developing a software program to sift out the desired electron signals. This initial solution allowed them to collect higher-quality data while addressing the actual sources of noise. “We demonstrated that software could remove certain types of noise from the data without losing the very small signals we want to see” said Brian Kirby, the BNL post-doc leading the evaluation of the software fix.

    5
    A comparison of particle interaction signals before and after MicroBooNE researchers removed the excess noise.

    With the software in place, the researchers could make the necessary changes to the detector’s hardware. They tackled the power supply noise by replacing the part that, just like your laptop charger, converts a higher voltage to a stable lower voltage that the cold electronics require. To combat the noise associated with generating the tank’s electric field, the researchers added a filter that would stabilize the high voltage. They eliminated more than eighty percent of the original noise with these hardware changes alone, and reduced it even further by then reapplying the software filters.

    The reconstructed neutrino paths are now sharply clear, like the burst of a small firework that was previously obscured by fog. These clean tracks are absolutely vital as the MicroBooNE team is implementing pattern recognition software to “train” a computer to pick out different types of neutrino collisions.

    “This is a really big deal in terms of pushing the field forward,” says Qian. “The lessons we learned will feed back to the next generation of technology development. For this kind of technology, there’s no way we can do it ‘just right’ the first time. We need to try it and improve it, try it and improve it.”

    The MicroBooNE collaboration will continue doing just that, trying and improving, as it lays the groundwork for DUNE, the biggest neutrino experiment ever attempted.

    Brookhaven’s work on MicroBooNE was funded by the DOE Office of Science (HEP) and the National Science Foundation.

    See the full article here .

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
    i1

     
  • richardmitnick 3:30 pm on August 4, 2017 Permalink | Reply
    Tags: , , , , , Neutrinos, , ,   

    From Symmetry: “The birth of a black hole, live” 09/09/15 

    Symmetry Mag

    Symmetry

    09/09/15 [this is old, but a lot of sites are featuring it again.]
    Lauren Biron

    1
    NASA/CXC/M.Weiss

    Scientists hope to use neutrino experiments to watch a black hole form.

    Black holes fascinate us. We easily conjure up images of them swallowing spaceships, but we know very little about these strange objects. In fact, we’ve never even seen a black hole form. Scientists on neutrino experiments such as the upcoming Deep Underground Neutrino Experiment hope to change that.

    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

    “You’ve got to be a bit lucky,” says Mark Thomson, DUNE co-spokesperson. “But it would be one of the major discoveries in science. It would be absolutely incredible.”

    Black holes are sometimes born when a massive star, typically more than eight times the mass of our own sun, collapses. But there are a lot of questions about what exactly happens during the process: How often do these collapsing stars give rise to black holes? When in the collapse does the black hole actually develop?

    What scientists do know is that deep in the dense core of the star, protons and electrons are squeezed together to form neutrons, sending ghostly particles called neutrinos streaming out. Matter falls inward. In the textbook case, matter rebounds and erupts, leaving a neutron star. But sometimes, the supernova fails, and there’s no explosion; instead, a black hole is born.

    DUNE’s gigantic detectors, filled with liquid argon, will sit a mile below the surface in a repurposed goldmine. While much of their time will be spent looking for neutrinos sent from Fermi National Accelerator Laboratory 800 miles away, the detectors will also have the rare ability to pick up a core collapse in our Milky Way galaxy – whether or not that leads to a new black hole.

    The only supernova ever recorded by neutrino detectors occurred in in 1987, when scientists saw a total of 19 neutrinos. Scientists still don’t know if that supernova formed a black hole or a neutron star—there simply wasn’t enough data. Thomson says that if a supernova goes off nearby, DUNE could see up to 10,000 neutrinos.

    DUNE will look for a particular signature in the neutrinos picked up by the detector. It’s predicted that a black hole will form relatively early in a supernova. Neutrinos will be able to leave the collapse in great numbers until the black hole emerges, trapping everything—including light and neutrinos—in its grasp. In data terms, that means you’d get a big burst of neutrinos with a sudden cutoff.

    Neutrinos come in three types, called flavors: electron, muon and tau. When a star explodes, it emits all the various types of neutrinos, as well as their antiparticles.

    They’re hard to catch. These neutrinos arrive with 100 times less energy than those arriving from an accelerator for experiments, which makes them less likely to interact in a detector.

    Most of the currently running, large particle detectors capable of seeing supernova neutrinos are best at detecting electron antineutrinos—and not great at detecting their matter equivalents, electron neutrinos.

    “It would be a tragedy to not be ready to detect the neutrinos in full enough detail to answer key questions,” says John Beacom, director of the Center for Cosmology and Astroparticle Physics at The Ohio State University.

    Luckily, DUNE is unique. “The only one that is sensitive to a huge slug of electron neutrinos is DUNE, and that’s a function of using argon [as the detector fluid],” says Kate Scholberg, professor of physics at Duke University.

    It will take more than just DUNE to get the whole picture, though. Getting an entire suite of large, powerful detectors of different types up and running is the best way to figure out the lives of black holes, Beacom says.

    There is a big scintillator detector, JUNO, in the works in China, and plans for a huge water-based detector, Hyper-K, in Japan.

    JUNO Neutrino detector, at Kaiping, Jiangmen in Southern China

    Hyper-Kamiokande, a neutrino physics laboratory located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

    Gravitational wave detectors such as LIGO could pick up additional information about the density of matter and what’s happening in the collapse.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    “My dream is to have a supernova with JUNO, Hyper-K and DUNE all online,” Scholberg says. “It would certainly make my decade.”

    The rate at which neutrinos arrive after a supernova will tell scientists about what’s happening at the center of a core collapse—but it will also provide information about the mysterious neutrino, including how they interact with each other and potential insights as to how much the tiny particles actually weigh.

    Within the next three years, the rapidly growing DUNE collaboration will build and begin testing a prototype of the 40,000-ton liquid argon detector. This 400-ton version will be the second-largest liquid-argon experiment ever built to date. It is scheduled for testing at CERN starting in 2018.

    DUNE is scheduled to start installing the first of its four detectors in the Sanford Underground Research Facility in 2021.

    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 11:43 am on July 31, 2017 Permalink | Reply
    Tags: , , , , , Neutrinos, ,   

    From FNAL: “ICARUS arrives at Fermilab” 

    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.

    July 31, 2017
    Leah Hesla

    1
    The ICARUS detector pulls in to the Fermilab site on July 26. Photo: Reidar Hahn

    After six weeks’ passage across the ocean, up rivers and on the road, the newest member of Fermilab’s family of neutrino detectors has arrived.

    The 65-foot-long ICARUS particle detector pulled into Fermilab aboard two semi-trucks on July 26 to an excited gathering who welcomed the detector, which has spent the last three years at the European laboratory CERN, to its new home.

    “We’ve waited a long time for ICARUS to get here, so it’s thrilling to finally see this giant, exquisite detector at Fermilab,” said scientist Peter Wilson, who leads the Fermilab Short-Baseline Neutrino Program. “We’re looking forward to getting it online and operational.”

    The ICARUS detector will be instrumental in helping an international team of scientists at the Department of Energy’s Fermilab get a bead on the slippery neutrino, the most ubiquitous yet least understood matter particle in the universe. The neutrino passes through outer space, metal, you and me without leaving a trace. Scientists have observed three types of neutrino. As it travels, it continually slips in and out of its various identities.

    Previous neutrino experiments have seen hints of yet another type, and ICARUS will hunt for evidence of this unconfirmed fourth. If found, the fourth neutrino could provide a new way of modeling dark matter, another of nature’s mysterious phenomena, one that makes up a whopping 23 percent of the universe. (Ordinary matter makes up only 4 percent of the universe.) A fourth neutrino would also change scientists’ fundamental picture of how the universe works.

    Fermilab is ICARUS detector’s second home. From 2010 to 2014, the Italian National Institute for Nuclear Physics’ Gran Sasso laboratory built and operated ICARUS to study neutrinos using a neutrino beam sent straight through the Earth’s mantle from CERN in Switzerland, about 600 miles away.

    INFN Gran Sasso ICARUS, since moved to FNAL

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

    ICARUS’ lead scientist, Nobel laureate Carlo Rubbia, innovated the use of liquid argon to detect neutrinos.

    ICARUS is the largest liquid-argon neutrino detector in the world. Its great mass — it will be filled with 760 tons of liquid argon — gives neutrinos, always reluctant to interact with anything, plenty of opportunities to come into contact with an argon nucleus. The charged particles resulting from the interaction create tracks that scientists can study to learn more about the neutrino that triggered them.

    In 2014, after the ICARUS experiment wrapped up in Italy, its detector was delivered to CERN. Since then, CERN and INFN have been improving the detector, refurbishing it for Fermilab’s mission. CERN completed the project in May and sent ICARUS on its trans-Atlantic voyage in June.

    “This is really exciting — to have the world’s original, large-scale liquid-argon neutrino detector at Fermilab,” said Cat James, senior scientist on Fermilab’s Short-Baseline Neutrino Program.

    Fermilab’s Short-Baseline Neutrino Program involves three neutrino detectors. ICARUS is one, and now that it has safely landed at Fermilab, it will be installed as part of the program. Another detector, MicroBooNE, has been in operation since 2015.

    FNAL/MicrobooNE

    The construction of the third, called the Short-Baseline Near Detector, is in progress.

    FNAL Short-Baseline Near Detector under construction

    All three use liquid argon to detect the elusive neutrino.

    The development and use of liquid-argon technology for the three detectors will be further wielded for Fermilab’s new flagship experiment, the 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

    Fermilab and South Dakota’s Sanford Underground Research Laboratory broke ground on the new experiment on July 21.

    “We’re really looking forward to working with our international partners as we get ICARUS ready for first beam,” James said.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    FNAL Icon
    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.

     
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