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  • richardmitnick 3:40 pm on January 10, 2019 Permalink | Reply
    Tags: , ArgoNeuT, , Liquid-argon detectors, Neutrinos,   

    From Fermi National Accelerator Lab: “Identifying lower-energy neutrinos with a liquid-argon particle detector” 

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    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    An experiment at the Department of Energy’s Fermilab has made a significant advance in the detection of neutrinos that hide themselves at lower energies.

    The ArgoNeuT experiment recently demonstrated for the first time that a particular class of particle detector — those that use liquid argon ­— can identify signals in an energy range that particle physicists call the “MeV range.”

    Fermilab ArgoNeuT

    It’s the first substantive step in confirming that researchers will be able to detect a wide energy range of neutrinos — even those at the harder-to-catch, lower energies — with the international Deep Underground Neutrino Experiment, or DUNE, hosted by Fermilab. DUNE is scheduled to start up in the mid-2020s.

    Neutrinos are lightweight, elusive and subtle particles that travel close to the speed of light and hold clues about the universe’s evolution. They are produced in radioactive decays and other nuclear reactions, and the lower their energy, the harder they are to detect.

    In general, when a neutrino strikes an argon nucleus, the interaction generates other particles that then leave detectable trails in the argon sea. These particles vary in energy.

    2
    This is a visual display of an ArgoNeuT event showing a long trail left behind by a high energy particle traveling through the liquid argon accompanied by small blips, indicated by the arrows, caused by low energy particles.

    Scientists are fairly adept at teasing out higher-energy particles — those with more than 100 MeV (or megaelectronvolts) — from their liquid-argon detector data. These particles zip through the argon, leaving behind what look like long trails in visual displays of the data.

    Sifting out particles in the lower, single-digit-MeV range is tougher, like trying to extract the better hidden needles in the proverbial haystack. That’s because lower-energy particles don’t leave as much of a trace in the liquid argon. They don’t so much zip as blip.

    Indeed, after simulating neutrino interactions with liquid argon, ArgoNeuT scientists predicted that MeV-energy particles would be produced and would be visible as tiny blips in the visual data. Where higher-energy particles show as streaks in the argon, the MeV particles’ telltale signature would be small dots.

    And this was the challenge ArgoNeuT researchers faced: How do you locate the tiny blips and dots in the data? And how do you check that they signify actual particle interactions and are not merely noise? The typical techniques, the methods for identifying long tracks in liquid argon, wouldn’t apply here. Researchers would have to come up with something different.

    And so they did: ArgoNeuT developed a method to identify and reveal blip-like signals from MeV particles. They started by comparing two different categories: blips accompanied by known neutrino events and blips unaccompanied by neutrino events. Finally, they developed a new low-energy-specific reconstruction technique to analyze ArgoNeuT’s actual experimental data to look for them.

    And they found them. They observed the blip signals, which matched the simulated results. Not only that, but the signals came through loud and clear: ArgoNeuT identified MeV signals as a 15 sigma excess, far higher than the standard for claiming an observation in particle physics, which is 5 sigma (which means that there’s a 1 in 3.5 million chance that the signal is a fluke.)

    ArgoNeuT’s result demonstrates a capacity of crucial importance for measuring MeV neutrino events in liquid argon.

    Intriguingly, neutrinos born inside a supernova also fall into MeV range. ArgoNeuT’s result gives DUNE scientists a leg up in one of its research goals: to improve our understanding of supernovae by studying the torrent of neutrinos that escape from inside the exploding star as it collapses.

    The enormous DUNE particle detector, to be located underground at Sanford Lab in South Dakota, will be filled with 70,000 tons of liquid argon. When neutrinos from a supernova traverse the massive volume of argon below Earth’s surface, some will bump into the argon atoms, producing signals collected by the DUNE detector. Scientists will use the data amassed by DUNE to measure supernova neutrino properties and fill in the picture of the star that produced them, and even potentially witness the birth of a black hole.

    Particle detectors picked up a handful of neutrino signals from a supernova in 1987, but none of them were liquid-argon detectors. (Other neutrino experiments use, for example, water, oil, carbon or plastic as their detection material of choice.) DUNE scientists need to understand what the lower-energy signals from a supernova would look like in argon.

    The ArgoNeuT collaboration is the first experiment to help answer that question, providing a kind of first chapter in the guidebook on what to look for when a supernova neutrino meets argon. Its achievement could bring us a little closer to learning what these messengers from outer space will have to tell us.

    Learn more.

    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.


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    Dark Energy Camera [DECam], built at FNAL

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  • richardmitnick 1:01 pm on December 25, 2018 Permalink | Reply
    Tags: "United States and France express interest to collaborate on construction of superconducting particle accelerator at Fermilab and the Deep Underground Neutrino Experiment, , , , , Neutrinos, ,   

    From Fermi National Accelerator Lab: “United States and France express interest to collaborate on construction of superconducting particle accelerator at Fermilab and the Deep Underground Neutrino Experiment” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    December 19, 2018

    The U.S. Department of Energy (DOE), the French Atomic Energy Commission (CEA) and the French National Center for Scientific Research (CNRS) have signed statements this month expressing interest to collaborate on high-tech international particle physics projects that are planned to be hosted at DOE’s Fermi National Accelerator Laboratory.

    The three agencies indicated plans to work together on the development and production of technical components for PIP-II (Proton Improvement Plan-II), a major DOE particle accelerator project with substantial international contributions. In addition, CNRS and CEA also plan to collaborate on the construction of the Fermilab-hosted Deep Underground Neutrino Experiment (DUNE), an international flagship science project that will unlock the mysteries of neutrinos — subatomic particles that travel close to the speed of light and have almost no mass.

    1
    DOE Undersecretary for Science Paul Dabbar (left) and Vincent Berger, Director of Fundamental Research at the CEA, at the signing ceremony in France on Dec. 11. The signing with CNRS took place on Dec. 19.

    The construction of a 176-meter-long superconducting particle accelerator is the centerpiece of the PIP-II project. The new accelerator upgrade will become the heart of the Fermilab accelerator complex and provide the proton beam to power a broad program of accelerator-based particle physics research for many decades to come. In particular, PIP-II will enable the world’s most powerful high-energy neutrino beam to power DUNE. The experiment requires enormous quantities of neutrinos to discover the role these particles played in the formation of the early universe. The first delivery of particle beams to DUNE is scheduled for 2026.

    “The collaboration on PIP-II and DUNE is a win-win situation for France and the U.S. Department of Energy,” said DOE Undersecretary for Science Paul Dabbar. “Scientists in France and the United States have a wealth of experience building components for superconducting particle accelerators and are contributing substantially to developing key technologies for DUNE. France’s expression of interest brings into the fold for the projects a partnership that has already seen great interest and contributions from across the globe.”

    Two French institutions — the departments of the Institute of Research into the Fundamental Laws of the Universe (Irfu), part of the French Atomic Energy Commission, and the CNRS IN2P3 laboratories: Institute of Nuclear Physics (IPN) and Linear Accelerator Laboratory (LAL) — are expected to build components for PIP-II. They both have extensive experience in the development of superconducting radio-frequency acceleration, which is the enabling technology for PIP-II, and are contributors to two major superconducting particle accelerator projects in Europe: the X-ray Free Electron Laser (XFEL) and the (ESS).


    European XFEL campus

    ESS European Spallation Source, currently under construction in Lund, Sweden.

    “For IN2P3, the DUNE experiment is of major scientific interest for the next decade, and this interest naturally extends to the PIP-II project, which actually aligns perfectly well with our experience on superconducting linac technologies,” said IN2P3 Director Reynald Pain. “Our scientific and technical teams are very excited to start this collaboration.”

    At the heart of the PIP-II project is the construction of an 800-million-electronvolt superconducting linear accelerator. The new accelerator will feature acceleration cavities made of niobium and double the beam energy of its predecessor. That boost will enable the Fermilab accelerator complex to achieve megawatt-scale proton beam power.

    “Irfu physicists are strongly involved in neutrino physics,” said Vincent Berger, Director of Fundamental Research at the CEA. “In this field, the DUNE experiment is particularly promising. In that context, contributing to the PIP-II project would be very interesting for our accelerator teams, who have strong experience in superconducting linacs. Our first discussions with Fermilab staff have been very stimulating.”

    In addition to France, other international partners are making significant contributions to PIP-II: India, the United Kingdom and Italy. DOE’s Argonne and Lawrence Berkeley National laboratories are also contributing key components to the project.

    France brings world-leading expertise and capabilities to the PIP-II project,” said PIP-II Project Director Lia Merminga. “It is a tremendous opportunity and honor to work with them and apply their demonstrated excellence to our project.”

    French scientists also plan to contribute to building the DUNE detector, a massive stadium-sized neutrino detector that will be located 1.5 kilometers underground at Sanford Underground Research Facility in South Dakota. Construction of prototype detectors are currently under way at the European Organization for Nuclear Research (CERN), the European particle physics laboratory located near the French-Swiss border. These prototypes include key contributions from French institutions in developing the dual-phase technology for one of the two ProtoDUNE detectors.

    “French scientists were among the founders of the DUNE experiment,” said Ed Blucher, DUNE collaboration co-spokesperson and professor at the University of Chicago. “Their enormous experience in detector and electronics development will be crucial to successful construction of the DUNE detectors.”

    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.


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    FNAL Short-Baseline Near Detector under construction

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    Dark Energy Camera [DECam], built at FNAL

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  • richardmitnick 12:43 pm on December 25, 2018 Permalink | Reply
    Tags: A primer on neutrinoless double-beta decay, , , , Neutrinos, , Particles and antiparticles, , The matter-antimatter conudrum   

    From Sanford Underground Research Facility: “A primer on neutrinoless double-beta decay” 

    SURF logo
    Sanford Underground levels

    From Sanford Underground Research Facility

    December 21, 2018
    Erin Broberg

    We asked Vincente Guiseppe about this theorized phenomenon and what it means for our understanding of the universe.

    1
    Vince Guiseppe points to the center of the shield that houses Majorana’s detectors. Credit Matthew Kapust

    At Sanford Underground Research Facility, we often talk about the Majorana Demonstrator’s search for “neutrinoless double-beta decay.”

    U Washington Majorana Demonstrator Experiment at SURF

    We say that this process could be incredibly important to understanding the imbalance of matter and anti-matter in the early universe. We explain how it is difficult to detect, demanding a miniscule background. We show photos of germanium detectors and ultra-pure copper shields, then describe immaculate cleanrooms and show off stylish Tyvek garb.

    But what exactly is neutrinoless double-beta decay?

    To find out, we went directly to the source. Dr. Vincente Guiseppe is the co-spokesperson for the Majorana Demonstrator collaboration and an assistant professor of physics and astronomy at the University of South Carolina.

    The best way to explain this mysterious process, Guiseppe said, is to work backward, defining one word at a time. So, let’s start at the end.

    Decay

    “There are two types of isotopes,” Guiseppe explains, “stable and radioactive.”

    The nuclei of a stable isotope are relaxed, meaning, they have a very low energy state. The nuclei of a radioactive isotope, on the other hand, are in a high energy state—they are very excited. But objects in nature prefer to be relaxed, Guiseppe said.

    So how do nuclei achieve a lower energy state? Through radioactive decay.

    “In nuclear physics, decay means a relaxation or a change of an atomic nucleus,” Guiseppe explained. “Nature allows protons and neutrons to change their makeup to achieve a desirable equilibrium. Once a nucleus is at the lowest energy state, we call it a stable isotope.”

    A lot of times, the words “radioactive decay” sound threatening. That’s because they often are used in the context of radiation you don’twant—radiation that is dangerous or destructive. In reality, though, radioactive decays are taking place all the time.

    “Potassium 40 is an isotope in our bodies,” said Guiseppe. “These isotopes decay 200,000 times per minute.”

    Radioactive decay is simply a nucleus reconfiguring itself through an interplay of matter and energy. Researchers with Majorana are looking for a natural process in which nuclei undergo such a change.

    Double-beta

    Every time an isotope decays, it loses a bit of energy in the form of a particle. Scientists classify types of decays by defining what type of particle comes out of the decay. In the case of beta decay, the particle emitted is an electron, or a beta particle.

    While there are multiple types of decays that could occur within the detector, Majorana researchers are looking specifically for a decay in which a beta particle is emitted.

    “And by ‘double-beta,’ we just mean we are looking for two of these decays simultaneously,” Guiseppe said.

    Neutrino(less)

    All reactions in nature, including beta decays, require symmetry, or a balance. Because of this symmetry, scientists originally assumed that every time an isotope underwent beta decay, it would emit an electron with a uniform energy. The problem was, it didn’t.

    “Electrons emitted from beta decays have a range of energies,” Guiseppe said. “Sometimes it is low, sometimes it is high, but it has this average value that was more or less half of what the scientists thought it should be.”

    This inconsistency lead researchers to realize that there must be another particle emitted—one that could not easily be detected, having no charge and very little mass. That missing particle was a neutrino.

    “When neutrinos were discovered in 1956, their addition to the beta-decay equation was confirmed,” said Guiseppe. “The neutrino balances this fundamental symmetry. With beta decay, there has to be both an electron and a neutrino produced.”

    Hold on a second. By definition, a beta decay must have an electron. By the laws of physics, it must have a neutrino. So why is Majorana looking for neutrinoless double-beta decay?

    “I just spent all this time explaining why you need a neutrino for a beta decay,” Guiseppe said with a smile. “And now, I’m going to say, no, you might not need a neutrino every time.”

    Scientists, Guiseppe said, have good reason to believe that neutrinos have the ability to do something very interesting—the ability to act like anti-neutrinos.

    Neutrinos — the maverick of the early universe

    To better understand the theory, we must first examine what is called the matter and antimatter asymmetry problem.

    According to the Big Bang theory, when the universe first formed, it had equal parts of matter and antimatter. This is a conundrum because, when matter and antimatter meet, they annihilate, leaving a universe filled with pure energy—no planets, stars or comets. And, most certainly, no life.

    So, what happened? Why did matter win out in the cosmic battle? Scientists are seeking an answer to how matter became the dominant form of matter in the universe.

    Many scientists believe there must have been a particle—very much like a neutrino—that acted very inconsistently with our current understanding of the laws of physics. This inconsistency, if detected, could answer the matter and anti-matter asymmetry puzzle. If just one particle acted differently, it could have upset the balance and allowed a remnant of matter to survive.

    For most particles, there exists matter and anti-matter. These types of matter are mirror images of each other—100 percent different. In the early 1930s, however, physicist Ettore Majorana theorized that neutrinos could be their own anti-particle—or what we call today, a Majorana particle.

    3
    Ettore Majorana

    “The claim is that maybe there’s no difference between neutrinos and what we call anti-neutrinos. They may be indistinguishable from each other,” said Guiseppe. “If they have that quality, it could help explain matter and antimatter asymmetry.”

    Neutrinoless double-beta decay — putting it all together

    If neutrinos have this property, it could answer a lot of questions for scientists; for example, how matter became the dominant form of matter in the universe, allowing for the creation of everything we see. But how might Majorana help discover it?

    Researchers are waiting for a double-beta decay to occur inside the Majorana Demonstrator. If it does, and if neutrinos can indeed act like their own antiparticle, then the two neutrinos necessary may interact, possibly being absorbed, making the double-beta decay seem neutrinoless.

    “If two beta decays occur in the Majorana Demonstrator, in close proximity to each other, and neutrinos do have this property, then we will detect the absence of neutrinos,” Guiseppe said.

    Should this rare event be detected, it will require rewriting the Standard Model of Particles and Interactions, our basic understanding of the physical world.

    “What isn’t up for debate,” Guiseppe concluded, “is that if neutrinos are indistinguishable from their anti-particle, then they will allow this neutrinoless double-beta decay process to take place. If they have this property, we will see the decay in Majorana. This is the best type of experiment we have to learn that.”

    See the full article here .


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

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

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

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

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

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.
    LUX/Dark matter experiment at SURFLUX/Dark matter experiment at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    LUX’s mission was to scour the universe for WIMPs, vetoing all other signatures. It would continue to do just that for another three years before it was decommissioned in 2016.

    In the midst of the excitement over first results, the LUX collaboration was already casting its gaze forward. Planning for a next-generation dark matter experiment at Sanford Lab was already under way. Named LUX-ZEPLIN (LZ), the next-generation experiment would increase the sensitivity of LUX 100 times.

    SLAC physicist Tom Shutt, a previous co-spokesperson for LUX, said one goal of the experiment was to figure out how to build an even larger detector.
    “LZ will be a thousand times more sensitive than the LUX detector,” Shutt said. “It will just begin to see an irreducible background of neutrinos that may ultimately set the limit to our ability to measure dark matter.”
    We celebrate five years of LUX, and look into the steps being taken toward the much larger and far more sensitive experiment.

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

    Fermilab LBNE
    LBNE

    U Washington Majorana Demonstrator Experiment at SURF

    The MAJORANA DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment in the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV. MAJORANA plans to collaborate with GERDA for a future tonne-scale 76Ge 0νββ search.

    LBNL LZ project at SURF, Lead, SD, USA

    CASPAR at SURF


    CASPAR is a low-energy particle accelerator that allows researchers to study processes that take place inside collapsing stars.

    The scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR). CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”

     
  • richardmitnick 1:25 pm on December 17, 2018 Permalink | Reply
    Tags: Anode plane assemblies, , Components from three continents, DUNE-Deep Underground Neutrino Experiment, , , , Neutrinos, , Short-Baseline Neutrino Detector, Sterile neutrino?,   

    From Symmetry: “First critical components arrive for SBND” 

    Symmetry Mag
    From Symmetry

    12/17/18
    Jim Daley

    International collaborators are delivering parts to be used in Fermilab’s Short-Baseline Neutrino program.

    1
    Photo by Reidar Hahn, Fermilab

    Major components for a new neutrino experiment at the US Department of Energy’s Fermi National Accelerator Laboratory are arriving at the lab from around the world. The components will be used in the upcoming Short-Baseline Near Detector, an important piece of the laboratory’s neutrino program. The first of four anode plane assemblies, highly sensitive electronic components, came to Fermilab in October. More are on their way.

    SBND is one of three particle detectors that make up the Short-Baseline Neutrino program at Fermilab. Neutrinos, renegade particles that are famously difficult to study, could provide scientists with clues about the evolution of the universe.

    The Short-Baseline Neutrino program, or SBN, focuses its search on a particular type of neutrino, called the sterile neutrino, which could be the explanation for unexpected results seen in several past neutrino experiments. The particle’s existence has been teased but never clearly confirmed.

    SBND will also be a testing ground for some of the technologies, including the anode plane assemblies, that will be used in the international Deep Underground Neutrino Experiment, known as DUNE, a megascience experiment hosted by Fermilab that is currently under construction in South Dakota.

    Fermilab’s three Short-Baseline Neutrino detectors will be positioned at various distances along the path of a neutrino beam generated by Fermilab’s particle accelerators.

    “The reason you have three detectors is that you want to sample the neutrino beam along the beamline at different distances,” says Ornella Palamara, SBND co-spokesperson and neutrino scientist at Fermilab.

    Of the three, SBND will be the nearest to the beam source at a distance of 110 meters. The other two, MicroBooNE and ICARUS, are 470 meters and 600 meters from the source, respectively. MicroBooNE has been taking data since 2015. ICARUS, installed earlier this year, is expected to begin taking data in 2019.

    FNAL Short-Baseline Near Detector

    FNAL/MicroBooNE

    FNAL/ICARUS

    As neutrinos pass through one detector after the other, some of them leave behind traces in the detectors. SBN scientists will analyze this information to search for firm evidence of the hypothesized but never seen member of the neutrino family.

    Making a (dis)appearance

    Neutrinos come in one of three lepton flavors, or types, which correspond to three other particles: electron, muon and tau. They change from one flavor into another as they travel through space, a behavior called oscillation. Neutrinos are known to oscillate in and out of the three flavors, but only further evidence will help scientists determine whether they also oscillate into a fourth type—a sterile neutrino.

    SBN scientists will look for signs of neutrinos oscillating into the new type.

    “The overall goal of the SBN program is to perform a definitive measurement that tests the possibility of sterile neutrino oscillations,” Palamara says.

    Sterile neutrinos are hypothetical particles that don’t interact with matter at all. (The neutrinos we’re familiar with do interact, but only rarely.) In 1995, results from the LSND experiment at Los Alamos National Laboratory hinted at the possibility of the sterile neutrino’s existence, but so far, no one has confirmed it. Results from the MiniBooNE experiment at Fermilab also indicate that something is going on with neutrinos that we don’t yet fully understand.

    FNAL/MiniBooNE

    SBND, as the first detector in the beam, will record the number of electron and muon neutrinos that pass through it before oscillation can occur. The vast majority of them—about 99.5 percent—will be muon neutrinos. By the time of their arrival at the far detectors, MicroBooNE and ICARUS, a few out of every thousand muon neutrinos may have converted into electron neutrinos.

    “The SBN program is powerful because you can measure this oscillation by looking at two different effects,” Palamara says.

    One is that the far detectors see more electron neutrinos than expected. This could be evidence that sterile neutrinos are also present: The neutrinos could be converting into and out of sterile neutrino states in a way that produces an excess of electron neutrinos.

    The other is that the far detectors see fewer muon neutrinos than expected—the muon neutrinos spotted in SBND “disappear”—because they converted into sterile neutrinos.

    Either effect could indicate the existence of the new particle.

    “Having a single experiment where we can see electron neutrino appearance and muon neutrino disappearance simultaneously and make sure their magnitudes are compatible with one another is enormously powerful for trying to discover sterile neutrino oscillations,” says David Schmitz, SBND co-spokesperson and assistant professor at the University of Chicago. “The near detector substantially improves our ability to do so.”

    Components from three continents

    SBND will be a 4-by-4-by-5-meter tank—the size of a large bedroom—filled with liquid argon. Its active liquid-argon mass—the volume monitored by the anode plane assemblies, or APAs—comes to 112 tons. The APAs, situated inside the detector, are huge frames covered with thousands of delicate sense wires. An electric field lies between the wire planes and a cathode plane.

    When a neutrino collides with the nucleus of an argon atom, charged particles are produced. These particles stream through the liquid volume, ionizing argon atoms as they pass by. The ionization produces thousands of free electrons, which “drift” under the influence of the electric field toward the APAs, where they are detected. By collecting these clouds of electrons on the wires, scientists create detailed images of the tracks of the particles emerging from a collision, which give information about the original neutrino that triggered the interaction.

    The construction of the wire planes is a collaboration between a group of universities in the United Kingdom funded by the Science and Technology Facilities Council, part of UK Research and Innovation, and another group of universities in the United States funded by a grant from the National Science Foundation. The US effort to build the wire planes was a collaboration between Syracuse University, the University of Chicago and Yale University. In the United Kingdom, Lancaster University, Manchester University and the University of Sheffield contributed to the effort.

    The APA technology will also be an integral part of DUNE, which will be the world’s largest liquid-argon neutrino detector when complete. The National Science Foundation recently funded a planning grant for DUNE’s anode plane assemblies; the NSF has a long history of pioneering investments in major particle physics experiments, including several neutrino experiments.

    Institutions in Europe, South America and the United States are helping build SBND’s various components. In all, more than 20 institutions on three continents are involved in the effort. Another dozen are collaborating on software tools to analyze data once the detector is operational, Schmitz says.

    “Being part of an international collaboration is great,” Palamara says. “Of course, there are challenges, but it’s fantastic to see people coming from all around the world to work on the program. Having pieces of the detector built in different places and then seeing everything come together is exciting.”

    Assembly of SBND is expected to finish in fall 2019, after which the detector will be installed in its building along the accelerator-generated neutrino beam. SBND is scheduled to be commissioned and begin receiving beam in June 2020.

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 12:36 pm on November 28, 2018 Permalink | Reply
    Tags: , , , , Hints of a ‘sterile’ neutrino, Neutrinos,   

    From FNAL via COSMOS Magazine: “Hints of a ‘sterile’ neutrino” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.
    via

    Cosmos Magazine bloc

    COSMOS Magazine

    Curious result could point to flaws in the Standard Model of particle physics.

    Standard Model of Elementary Particles


    Something missing? The Standard Model admits three types of neutrino. New evidences suggest a fourth might also exist. generalfmv/Getty Images

    Scientists may have caught a glimpse of a new breed of particle from an unseen side of the universe.

    Researchers conducting an exercise known as the Mini Booster Neutrino Experiment (MiniBooNE) at Fermilab near Chicago in the US have painstakingly compiled measurements of neutrinos over the last 15 years.

    FNAL/MiniBooNE

    The experiment has yielded only the three types of neutrinos described in the Standard model: electron neutrinos, muon neutrinos and tau neutrinos. But now the scientists have published a paper in the journal Physical Review Letters, reporting a possible trace of a fourth.

    Neutrinos are subatomic particles less than a million times lighter than electrons. They are one of the three components of matter, along with electrons and quarks, which make up the nuclei in atoms. Each component has two heavier counterparts, which decay after fractions of seconds: this array of particles in threes is known as the Standard Model.

    A fourth particle that bucks the threefold pattern could be big news says MiniBooNE spokesman Rex Tayloe, from Indiana University in the United States.

    “If that is the correct explanation of the signal, it is an important and far-reaching result as it opens up the field of particle physics to a new set of particles – beyond the current Standard Model,” he says.

    Neutrinos are already the most mysterious particle in the Standard Model. They are preposterously numerous – 100 million neutrinos pass through the human body every second, barely interacting.

    And because they interact so weakly, only a tiny number are ever detected. Their mass is still uncertain. It is so small that for a long time it was thought to be zero.

    Unlike quarks and electrons, which decay from unstable, heavy forms into lighter, stable ones, neutrinos continually change form, slipping between the three forms as they as they torpedo through space at close to the speed of light.

    It is this shape-changing that MiniBooNE has been studying, using a 541-metre beam of neutrinos. The scientists create them by smashing high-energy protons into a target of the metal beryllium, which creates unstable particles called pions that quickly decay, creating neutrinos.

    The process creates a type called muon neutrinos, which are directed to MiniBooNE’s detector, a 12.2-metre sphere filled with 818 tonnes of pure mineral oil, lined with 1520 photomultipliers that catch tiny flashes of light caused by the occasional neutrino interaction.

    The Standard Model predicts a small percentage of muon neutrinos will change into electron neutrinos in the half-kilometre flight. But MiniBooNE found more of these than expected.

    One possible explanation for this rapid oscillation is a fourth neutrino form – but because it has never been detected it must not even interact in the incredibly weak way that the other three forms do. The scientists term it a sterile neutrino.

    The hint of a new, invisible particle raises scientists’ hopes for a whole new family that could help solve puzzles of dark matter, dark energy and the imbalance of matter and antimatter in the universe.

    But the isuue is far from resolved. While MiniBooNE’s result is line with an experiment in the nineties at Los Alamos in New Mexico in the US, other experiments have failed to confirm the same effect, which has physicists scratching their heads.

    Solutions could be found by new larger experiments that are coming online, such as DUNE, which tracks neutrinos over a 1300-kilometre path under the US.

    SURF DUNE LBNF Caverns at Sanford Lab


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

    There is also the huge Japanese detector Hyper-Kamiokande, and a larger scale version of MiniBooNE.

    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.

    It’s possible the new data will overturn the sterile neutrino theory as a systematic error of some sort. But even if so, given their history, the mysterious particles are still likely to have some surprises in store.

    See the full article here .


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  • richardmitnick 3:23 pm on November 20, 2018 Permalink | Reply
    Tags: , , , , , Neutrinos,   

    From Fermi National Accelerator Lab: “How to build a towering millikelvin thermometer” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    November 15, 2018
    Jim Daley

    Cary Kendziora had expected the long, slender temperature profile monitor to droop a bit, but not as much as this. As part of a joint project with the University of Hawaii at Manoa, Kendziora, a mechanical engineer at the U.S. Department of Energy’s Fermilab, had designed the device to measure the variation in temperature inside a massive neutrino detector located at the European laboratory CERN. The detector, the size of a small house, is filled with liquid argon. The temperature profile monitor is a solid piece of metal about 8 meters tall — about two stories tall — and as thin as a curtain rod. It bowed considerably when it was horizontal.

    Kendziora said he’d never worked with such a long, solid piece of metal that was also so narrow.

    “It turned out to be a lot more flexible than I imagined because of its length,” Kendziora said. “That was a surprise.”

    As a workaround, he helped build an exoskeleton support to keep the device rigid while it was being installed.

    The detector, one of two known as the ProtoDUNE detectors, contains 770 tons of liquid argon maintained at temperatures around 90 Kelvin.

    CERN Proto Dune

    Cern ProtoDune

    That’s a chilling minus 300 degrees Fahrenheit. As particles pass through the detector, they occasionally smash into the nuclei of argon atoms. The particles emerging from these collisions release electrons from argon atoms as they pass by. These electrons drift toward sensors that record their tracks. The tracks, in turn, give scientists information about the particle that started the reaction.

    2
    The temperature profiler from one of the ProtoDUNE detectors stands 8 meters tall. Photo: Cary Kendziora

    The ProtoDUNE detectors are prototypes for the international, Fermilab-hosted Deep Underground Neutrino Experiment. The DUNE detector, expected to be complete in the mid-2020s, will be mammoth, comprising four modules that are each nearly as long as a football field.

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

    SURF DUNE LBNF Caverns at Sanford Lab

    FNAL DUNE Argon tank at SURF

    In liquid-argon detectors like DUNE and the ProtoDUNE detector, monitoring the variation in internal temperature is important because it’s correlated to the argon’s purity. ProtoDUNE contains 770 tons of liquid argon. DUNE will hold 70,000 tons. At this scale, the purification efficiency has to be checked regularly. If the argon doesn’t mix properly, it begins to stratify into layers of different temperatures, which can affect how far electrons can drift.

    “If the argon is pure, the electrons can drift the distance to the ProtoDUNE sensors, no problem,” said Jelena Maricic, an associate professor of physics at the University of Hawaii at Manoa who leads the group that worked on the design, construction and installation of the ProtoDUNE dynamic temperature profile monitor, along with Kendziora.

    But impurities have a great affinity for electrons and can trap them on their way to the sensors. And if they’re trapped, they won’t be detected, or at least not as easily.

    The temperature profile monitor hangs vertically from the detector’s ceiling near one corner of the detector, taking readings of the circulating liquid argon. By monitoring the argon’s temperature, scientists will be able to tell right away whether any problems are developing in the detector.

    Calibration by cross-reference

    Designing and building a temperature profile monitor that is accurate to within tens of millikelvin inside a massive liquid-argon detector is no small feat. While the degree of bowing was an unexpected problem, it was hardly the most difficult challenge to overcome. Kendziora ticked off a laundry list of them.

    “It had to be electrically and thermally isolated, and leak-tight,” he said. “And it’s a high-purity application, so all the materials had to be selected based on their not contributing any contaminants to the liquid. All the little threaded holes that the components are screwed into had to be vented so they wouldn’t trap any gas that would give off oxygen over a long period of time. All the parts had to be cleaned.”

    The entire design of the profile monitor also needed to address a unique question: How do you calibrate a probe that is sealed inside a giant box full of liquid argon? Erik Voirin, an engineer at Fermilab, and Yujing Sun, a postdoc in Maricic’s lab, independently hit upon the same, elegant idea.

    The team designed the profile monitor with an array of 23 motor-driven, remotely moveable sensors along its 8-meter height. Each takes a reading of the argon immediately surrounding it. And since they’re moveable, not only can a sensor take the temperature in multiple locations, but a single location’s temperature can be read out by more than one sensor.

    4
    The profile monitor is outfitted with an array of 23 motor-driven, remotely moveable sensors along its 8-meter height. Each takes a reading of the argon immediately surrounding it. Photo: Cary Kendziora

    Voirin, a thermal-fluids engineer, performed the computational fluid dynamics simulations for ProtoDUNE. Sun tested and demonstrated the idea to work with the prototype using just four sensors in 2017, deploying the rod in the 35-ton liquid-argon detector.

    “Our system allows you to move the sensors along the vertical axis and perform cross-calibration,” Maricic said.

    One could use sensor A to take the temperature at, say, the 3-meter mark, and then check its reading against sensor B’s at the same location. That way, scientists can determine if any sensor is out of whack.

    Maricic said that the University of Hawaii group team, will be performing the cross-calibration in the late November or early December.

    The DUNE far detector will require a similar temperature profile monitor that adheres to the same set of strict requirements that the ProtoDUNE detector needed – but with one difference. DUNE is much larger than ProtoDUNE, so its profile monitor needs to be scaled up accordingly. It will be 15 meters long — nearly double the length of the prototype profile monitor.

    “I don’t have a solution for the long length,” Kendziora says, other than to construct another extensive support infrastructure.

    Another engineering effort for DUNE— and he’s on top of it.

    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 1:44 pm on November 10, 2018 Permalink | Reply
    Tags: A pair of inspiraling neutron stars, A possible scenario would be a neutrino created in the relativistic outflows of a merger of binary neutron stars or black holes or the core-collapse of a supernova all cataclysmic cosmic environments , , , , , , , , , , Neutrinos, The detection of gravitational waves and neutrinos from a single source would set a new milestone in multimessenger astronomy, The scrutiny of an astrophysical source with three different messengers would not only be the next breakthrough in the field but would also confirm that multimessenger astronomy is the only path to a ,   

    From U Wisconsin IceCube Collaboration: “Multimessenger searches for sources of gravitational waves and neutrinos” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

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

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

    From From U Wisconsin IceCube Collaboration

    09 Nov 2018
    Sílvia Bravo

    1
    Artist’s now iconic illustration of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays and neutrinos that are shot out just seconds after the gravitational waves. Image: NSF/LIGO/Sonoma State University/A. Simonnet

    Last year was an extraordinary year for multimessenger astrophysics. In August 2017, a gravitational wave and its electromagnetic counterpart emission were detected from a pair of inspiraling neutron stars. Only a month later, a high-energy neutrino was detected at the South Pole and electromagnetic follow-up observations helped identify the first likely source of very high energy neutrinos and cosmic rays.

    Since then, the dream of astrophysicists has been to join neutrinos and gravitational waves in the detection of a multimessenger source. According to our understanding of the extreme universe, a possible scenario would be a neutrino created in the relativistic outflows of a merger of binary neutron stars or black holes or the core-collapse of a supernova, all cataclysmic cosmic environments that should also produce gravitational waves.

    The IceCube, LIGO, Virgo, and ANTARES collaborations have used data from the first observing period of Advanced LIGO and from the two neutrino detectors to search for coincident neutrino and gravitational wave emission from transient sources.

    The goal was to explore the discovery potential of a multimessenger observation, i.e., of a source detection that needs both messengers to confirm its astrophysical origin. Scientists did not find any significant coincidence. The results, recently submitted to The Astrophysical Journal, set a constraint on the density of these sources.

    The detection of gravitational waves and neutrinos from a single source would set a new milestone in multimessenger astronomy, allowing the simultaneous study of the inner and outer processes powering high-energy emission from astrophysical objects.

    A joint detection would also significantly improve the localization of the source and enable faster and more precise electromagnetic follow-up observations. The scrutiny of an astrophysical source with three different messengers would not only be the next breakthrough in the field but would also confirm that multimessenger astronomy is the only path to a profound understanding of the extreme universe.

    Even though the current search was very limited in time, researchers have set a strong constraint for joint emission from core-collapse supernovas, while binary mergers remain secure as potential multimessenger sources of gravitational waves and high-energy neutrinos.

    This study used datasets, spanning less than 2.5 months, that are also limited by LIGO’s sensitivity, which will soon improve by a factor of 2. The addition of new LIGO and Virgo data as well as from IceCube and ANTARES will greatly increase the sensitivity of joint searches. In the longer term, future next-generation neutrino and gravitational wave detectors will boost the potential of discovery for these searches.

    See the full article here .

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

     
  • richardmitnick 4:55 pm on November 5, 2018 Permalink | Reply
    Tags: , Neutrinos, , Physicists measured Earth’s mass using neutrinos for the first time, ,   

    From Science News: “Physicists measured Earth’s mass using neutrinos for the first time” 

    From Science News

    November 5, 2018
    Emily Conover

    The tiny particles provide an independent test of some of the planet’s key properties.

    1
    PARTICLE PROBES Subatomic particles called neutrinos are created when spacefaring protons and other particles smash into Earth’s atmosphere (illustrated). Scientists have now used neutrinos to measure the Earth’s mass and the densities of its layers. Earth: Reto Stöckli, Nazmi El Saleous and Marit Jentoft-Nilsen/GSFC/NASA, adapted by E. Otwell

    Puny particles have given scientists a glimpse inside the Earth.

    For the first time, physicists have measured the planet’s mass using neutrinos, minuscule subatomic particles that can pass straight through the entire planet. Researchers also used the particles to probe the Earth’s innards, studying how the planet’s density varies from crust to core.

    Typically, scientists determine Earth’s mass and density by quantifying the planet’s gravitational pull and by studying seismic waves that penetrate the globe. Neutrinos provide a completely independent test of the planet’s properties. Made using data from the IceCube neutrino observatory at the South Pole, the new planetary profile agreed with traditional measurements, a trio of physicists reports November 5 in Nature Physics.

    U Wisconsin IceCube neutrino observatory

    U Wisconsin IceCube experiment at the South Pole



    U Wisconsin ICECUBE neutrino detector at the South Pole


    IceCube Gen-2 DeepCore PINGU


    IceCube reveals interesting high-energy neutrino events

    To make the measurement, the scientists studied high-energy neutrinos that were produced when protons and other energetic particles from space slammed into the Earth’s atmosphere. These neutrinos can zip clean through the entire Earth, but sometimes they smash into atomic nuclei and are absorbed instead. How often neutrinos get stopped in their tracks reveals the density of the stuff they’re traveling through.

    Neutrinos that arrived at the IceCube detector from different angles probed different layers of the Earth. For example, a neutrino coming from the opposite side of the planet, at the North Pole, would pass through the Earth’s crust, mantle and core before reaching the South Pole. But one that skimmed in at an angle might pass through only the crust. By measuring how many neutrinos came from various angles, the team inferred the densities of different parts of the Earth and its total mass.

    The technique doesn’t yet reveal anything new about the planet. But one day it might help scientists determine whether all of Earth’s mass comes from normal matter. Perhaps some of the mass is due to something that shuns neutrinos, such as a type of dark matter, a shadowy substance that scientists believe must exist to account for missing mass observed in measurements of other galaxies. Neutrinos could help physicists nail down whether the Earth harbors such dark matter within.

    See the full article here .


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  • richardmitnick 8:08 am on November 2, 2018 Permalink | Reply
    Tags: , Antimatter particles, “Majorana” particles: particles that are indistinguishable from their antimatter counterparts, , , , Neutrinos, , ,   

    From CERN: “Chasing a particle that is its own antiparticle” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    1 Nov 2018
    Ana Lopes

    1
    The ATLAS experiment at CERN. (Image: Maximilien Brice/CERN)

    Neutrinos weigh almost nothing: you need at least 250 000 of them to outweigh a single electron. But what if their lightness could be explained by a mechanism that needs neutrinos to be their own antiparticles? The ATLAS collaboration at CERN is looking into this, using data from high-energy proton collisions collected at the Large Hadron Collider (LHC).

    One way to explain neutrinos’ extreme lightness is the so-called seesaw mechanism, a popular extension of the Standard Model of particle physics.

    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.


    Standard Model of Particle Physics from Symmetry Magazine

    This mechanism involves pairing up the known light neutrinos with hypothetical heavy neutrinos. The heavier neutrino plays the part of a larger child on a seesaw, lifting the lighter neutrino to give it a small mass. But for this mechanism to work, both neutrinos need to be “Majorana” particles: particles that are indistinguishable from their antimatter counterparts.

    Antimatter particles have the same mass as their corresponding matter particles but have the opposite electric charge. So, for example, an electron has a negative electric charge and its antiparticle, the positron, is positive. But neutrinos have no electric charge, opening up the possibility that they could be their own antiparticles. Finding heavy Majorana neutrinos could not only help explain neutrino mass, it could also lead to a better understanding of why matter is much more abundant in the universe than antimatter.

    In an extended form of the seesaw model, these heavy Majorana neutrinos could potentially be light enough to be detected in LHC data. In a new paper, the ATLAS collaboration describes the results of its latest search for hints of these particles.

    ATLAS looked for instances in which both a heavy Majorana neutrino and a “right-handed” W boson, another hypothetical particle, could appear. They used LHC data from collision events that produce two “jets” of particles plus a pair of energetic electrons or a pair of their heavier cousins, muons.

    The researchers compared the observed number of such events with the number predicted by the Standard Model. They found no significant excess of events over the Standard Model expectation, indicating that no right-handed W bosons and heavy Majorana neutrinos took part in these collisions.

    However, the researchers were able to use their observations to excludepossible masses for these two particles. They excluded heavy Majorana neutrino masses up to about 3 TeV, for a right-handed W boson with a mass of 4.3 TeV. In addition, they explored for the first time the hypothesis that the Majorana neutrino is heavier than the right-handed W boson, placing a lower limit of 1.5 TeV on the mass of Majorana neutrinos. Further studies should be able to put tighter limits on the mass of heavy Majorana neutrinos in the hope of finding them – if, indeed, they exist.

    See the full article here.


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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 Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN 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

    CERN Proto Dune

    CERN Proto Dune

     
  • richardmitnick 2:49 pm on October 26, 2018 Permalink | Reply
    Tags: , , , , J-PARC accelerator, Neutrinos, , Super Kamiokande experiment, T2K (Tokai to Kamiokande) experiment   

    From Live Science: “Could Misbehaving Neutrinos Explain Why the Universe Exists?” 

    Livescience
    From Live Science

    October 24, 2018

    FNAL’s Don Lincoln

    1
    Credit: Shutterstock

    Scientists revel in exploring mysteries, and the bigger the mystery, the greater the enthusiasm. There are many huge unanswered questions in science, but when you’re going big, it’s hard to beat “Why is there something, instead of nothing?”

    That might seem like a philosophical question, but it’s one that is very amenable to scientific inquiry. Stated a little more concretely, “Why is the universe made of the kinds of matter that makes human life possible so that we can even ask this question?” Scientists conducting research in Japan have announced a measurement last month that directly addresses that most fascinating of inquiries. It appears that their measurement disagrees with the simplest expectations of current theory and could well point toward an answer of this timeless question.

    Their measurement seems to say that for a particular set of subatomic particles, matter and antimatter act differently.

    Matter v. Antimatter

    Using the J-PARC accelerator, located in Tokai, Japan, scientists fired a beam of ghostly subatomic particles called neutrinos and their antimatter counterparts (antineutrinos) through the Earth to the Super Kamiokande experiment, located in Kamioka, also in Japan.

    J-PARC Facility Japan Proton Accelerator Research Complex , located in Tokai village, Ibaraki prefecture, on the east coast of Japan

    Super-Kamiokande experiment. located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    This experiment, called T2K (Tokai to Kamiokande), is designed to determine why our universe is made of matter. A peculiar behavior exhibited by neutrinos, called neutrino oscillation, might shed some light on this very vexing problem.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan

    Asking why the universe is made of matter might sound like a peculiar question, but there is a very good reason that scientists are surprised by this. It’s because, in addition to knowing of the existence of matter, scientists also know of antimatter.

    In 1928, British physicist Paul Dirac proposed the existence of antimatter — an antagonistic sibling of matter. Combine equal amounts of matter and antimatter and the two annihilate each other, resulting in the release of an enormous amount of energy. And, because physics principles usually work equally well in reverse, if you have a prodigious quantity of energy, it can convert into exactly equal amounts of matter and antimatter. Antimatter was discovered in 1932 by American Carl Anderson and researchers have had nearly a century to study its properties.

    However, that “into exactly equal amounts” phrase is the crux of the conundrum. In the brief moments immediately after the Big Bang, the universe was full of energy. As it expanded and cooled, that energy should have converted into equal parts matter and antimatter subatomic particles, which should be observable today. And yet our universe consists essentially entirely of matter. How can that be?

    By counting the number of atoms in the universe and comparing that with the amount of energy we see, scientists determined that “exactly equal” isn’t quite right. Somehow, when the universe was about a tenth of a trillionth of a second old, the laws of nature skewed ever-so-slightly in the direction of matter. For every 3,000,000,000 antimatter particles, there were 3,000,000,001 matter particles. The 3 billion matter particles and 3 billion antimatter particles combined — and annihilated back into energy, leaving the slight matter excess to make up the universe we see today.

    Since this puzzle was understood nearly a century ago, researchers have been studying matter and antimatter to see if they could find behavior in subatomic particles that would explain the excess of matter. They are confident that matter and antimatter are made in equal quantities, but they have also observed that a class of subatomic particles called quarks exhibit behaviors that slightly favor matter over antimatter. That particular measurement was subtle, involving a class of particles called K mesons which can convert from matter to antimatter and back again. But there is a slight difference in matter converting to antimatter as compared to the reverse. This phenomenon was unexpected and its discovery led to the 1980 Nobel prize, but the magnitude of the effect was not enough to explain why matter dominates in our universe.

    Ghostly beams

    Thus, scientists have turned their attention to neutrinos, to see if their behavior can explain the excess matter. Neutrinos are the ghosts of the subatomic world. Interacting via only the weak nuclear force, they can pass through matter without interacting nearly at all. To give a sense of scale, neutrinos are most commonly created in nuclear reactions and the biggest nuclear reactor around is the Sun. To shield one’s self from half of the solar neutrinos would take a mass of solid lead about 5 light-years in depth. Neutrinos really don’t interact very much.

    Between 1998 and 2001, a series of experiments — one using the Super Kamiokande detector, and another using the SNO detector in Sudbury, Ontario ­­— proved definitively that neutrinos also exhibit another surprising behavior. They change their identity.

    SNOLAB, a Canadian underground physics laboratory at a depth of 2 km in Vale’s Creighton nickel mine in Sudbury, Ontario


    SNOLAB, Sudbury, Ontario, Canada.

    Physicists know of three distinct kinds of neutrinos, each associated with a unique subatomic sibling, called electrons, muons and taus. Electrons are what causes electricity and the muon and tau particle are very much like electrons, but heavier and unstable.

    The three kinds of neutrinos, called the electron neutrino, muon neutrino and tau neutrino, can “morph” into other types of neutrinos and back again. This behavior is called neutrino oscillation.

    Neutrino oscillation is a uniquely quantum phenomenon, but it is roughly analogous to starting out with a bowl of vanilla ice cream and, after you go and find a spoon, you come back to find that the bowl is half vanilla and half chocolate. Neutrinos change their identity from being entirely one type, to a mix of types, to an entirely different type, and then back to the original type.

    Antineutrino oscillations

    Neutrinos are matter particles, but antimatter neutrinos, called antineutrinos, also exist. And that leads to a very important question. Neutrinos oscillate, but do antineutrinos also oscillate and do they oscillate in exactly the same way as neutrinos? The answer to the first question is yes, while the answer to the second is not known.

    Let’s consider this a little more fully, but in a simplified way: Suppose that there were only two neutrino types — muon and electron. Suppose further that you had a beam of purely muon type neutrinos. Neutrinos oscillate at a specific speed and, since they move near the speed of light, they oscillate as a function of distance from where they were created. Thus, a beam of pure muon neutrinos will look like a mix of muon and electron types at some distance, then purely electron types at another distance and then back to muon-only. Antimatter neutrinos do the same thing.

    However, if matter and antimatter neutrinos oscillate at slightly different rates, you’d expect that if you were a fixed distance from the point at which a beam of pure muon neutrinos or muon antineutrinos were created, then in the neutrino case you’d see one blend of muon and electron neutrinos, but in the antimatter neutrino case, you’d see a different blend of antimatter muon and electron neutrinos. The actual situation is complicated by the fact that there are three kinds of neutrinos and the oscillation depends on beam energy, but these are the big ideas.

    The observation of different oscillation frequencies by neutrinos and antineutrinos would be an important step towards understanding the fact that the universe is made of matter. It’s not the entire story, because additional new phenomena must also hold, but the difference between matter and antimatter neutrinos is necessary to explain why there is more matter in the universe.

    In the current prevailing theory describing neutrino interactions, there is a variable that is sensitive to the possibility that neutrinos and antineutrinos oscillate differently. If that variable is zero, the two types of particles oscillate at identical rates; if that variable differs from zero, the two particle types oscillate differently.

    When T2K measured this variable, they found it was inconsistent with the hypothesis that neutrinos and antineutrinos oscillate identically. A little more technically, they determined a range of possible values for this variable. There is a 95 percent chance that the true value for that variable is within that range and only a 5 percent chance that the true variable is outside that range. The “no difference” hypothesis is outside the 95 percent range.

    In simpler terms, the current measurement suggests that neutrinos and antimatter neutrinos oscillate differently, although the certainty does not rise to the level to make a definitive claim. In fact, critics point out that measurements with this level of statistical significance should be viewed very, very skeptically. But it is certainly an enormously provocative initial result, and the world’s scientific community is extremely interested in seeing improved and more precise studies.

    The T2K experiment will continue to record additional data in hopes of making a definitive measurement, but it’s not the only game in town. At Fermilab, located outside Chicago, a similar experiment called NOvA is shooting both neutrinos and antimatter neutrinos to northern Minnesota, hoping to beat T2K to the punch.

    FNAL NOvA Near Detector


    FNAL/NOvA experiment map


    FNAL NOvA far detector in northern Minnesota


    NOvA Far Detector Block

    And, looking more to the future, Fermilab is working hard on what will be its flagship experiment, called DUNE (Deep Underground Neutrino Experiment), which will have far superior capabilities to study this important phenomenon.


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


    SURF DUNE LBNF Caverns at Sanford Lab

    While the T2K result is not definitive and caution is warranted, it is certainly tantalizing. Given the enormity of the question of why our universe seems to have no appreciable antimatter, the world’s scientific community will avidly await further updates.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
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