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  • richardmitnick 8:53 am on May 26, 2020 Permalink | Reply
    Tags: , , Neutrinos, ,   

    From Sanford Underground Research Facility: ‘Why DUNE? [Part III] Shedding light on the unification of nature’s forces” 

    SURF logo

    From Sanford Underground Research Facility


    Homestake Mining Company

    May 22, 2020
    Erin Broberg

    Part III in our series exploring the science goals of the international Deep Underground Neutrino Experiment [image below].

    1
    The Deep Underground Neutrino Experiment (DUNE) could help us learn more about physics beyond the Standard Model. Courtesy Fermilab

    Master theoretical physicists laid the foundations of the Standard Model throughout the second half of the twentieth century. With outstanding success, it explained how particles like protons, neutrons and electrons interact on a subatomic level. It also made Nobel Prize-winning predictions about new particles, such as the Higgs Boson, that were later observed in experiments. For decades, the Standard Model has been the scaffolding on which physicists drape quantum concepts from magnetism to nuclear fusion.

    Despite its remarkable dexterity and longevity, however, some physicists have described the Standard Model as “incomplete,” “ugly” and, in some instances, even “grotesque.”

    “The Standard Model is an effective theory, but we are not satisfied,” said Chang Kee Jung, a professor of physics at Stony Brook University. “Physicists, in some sense, are perfectionists. We always want to know exactly why things work a certain way.” While the Standard Model is incredibly useful, it is far from perfect.

    2
    A portion of the Lagrangian standard model transcribed by T.D. Gutierrez. Courtesy Symmetry Magazine.

    Standard Model of Particle Physics, Quantum Diaries

    In a bewildering example, the Standard Model predicted that neutrinos, the universe’s most abundant particle, would be massless. In 1998, the Super-Kamiokande experiment in Japan caught the Standard Model in a lie.

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

    Neutrinos do indeed have mass, albeit very little. Further complicating matters, the Standard Model doesn’t explain dark matter or dark energy; combined, these account for 95 percent of the universe. In other cases, the Standard Model requires physicists to begrudgingly plug in arbitrary parameters to reflect experimental data.

    Unwilling to ignore these flaws, physicists are looking for a new, more perfect model of the subatomic universe. And many are hoping that the Deep Underground Neutrino Experiment, hosted by the Department of Energy’s Fermi National Accelerator Laboratory, can put their theories to the test.

    Grander theories of the quantum world

    Leading alternatives to the Standard Model attempt to unify the three quantum forces: strong, weak and electromagnetic. Physicists have demonstrated that, at extremely high energies, the weak and electromagnetic force become indistinguishable. Many believe that the strong force can be unified in the same way.

    “Grand unification is the beautiful idea that there was a single force at the beginning of the universe, and what we see now is three manifestations of that original force,” said Jonathan Lee Feng, particle and cosmology theorist at the University of California, Irvine. This class of “Grand Unified Theories” is charmingly abbreviated as “GUTs.”

    In their search for a GUT, theorists have been a bit too successful. They haven’t created just one alternative to the Standard Model—they’ve created hundreds. These models unify quantum forces, explain the mass of a neutrino and eliminate many arbitrary parameters. Some are practical and bare-boned, others far-fetched and elaborate, but nearly all are mathematically solid.

    Even so, they can’t all be “right.”

    “You can write a logically and mathematically consistent theory, but that doesn’t mean it matches the real mechanisms of the universe,” Jung said. “Nature chooses its own way.”

    Testing physics beyond the Standard Model

    GUTs are a major branch of theory. But others also attempt to reshape our understanding of the universe. Surrounded by more models than could possibly be correct, theorists around the world are asking the universe for a nudge in the right direction.

    Just as the Standard Model predicted novel particles in the twentieth century that were later discovered through experimentation, new theories also predict never-before-seen phenomena. Some models predict the decay of a particle once thought immortal. Others hint at a fourth generation of neutrino. Still others foretell of particles that communicate between our realm and the realm of dark matter.

    “We can continue to speculate and refine these models, but if we actually witnessed one of these predictions, we’d have much more precise hints about where to go,” Feng said.

    Enter DUNE. The main goal of the international Deep Underground Neutrino Experiment is to keep a watchful eye on a beam of neutrinos traveling from Fermilab to detectors deep under the earth at Sanford Underground Research Facility. However, the experiment is also designed to be sensitive to a slew of interactions predicted by avant-garde theories. The observation of even one of these predictions would rule out dozens of theories and guide the next generation of quantum theory.

    Tuned to witness quantum strangeness

    Proton decay

    The Standard Model dictates that protons—basic building blocks of matter best known for how they clump with neutrons in the center of an atom—are stable particles, destined to live forever.

    However, many Grand Unified Theories have predicted that, eventually, protons will decay. While different models disagree on the specific mechanisms that cause this decay, the general consensus is that proton decay is a good place to start investigating physics beyond the Standard Model.

    To validate these theories, physicists just have to glimpse the death of a proton.

    In the early 1950s, Maurice Goldhaber, an esteemed physicist who later directed Brookhaven National Laboratory, postulated that protons live at least 10^16 years. If their lifespan were any shorter, the radiation from frequent decays would destroy the human body. Thus, Goldhaber said, you could “feel it in your bones” that the proton was long-lived. Over time, experiments determined that protons lifetime was even longer—at least 10^34 years.

    According to current estimates, you would have to watch one proton for a minimum of 100,000,000,000,000,000,000,000,000,000,000,000 years—without blinking—in order to see it decay. Sensible physicists aren’t quite that patient.

    By watching a multitude of protons at once, researchers can greatly increase their chances of seeing a decay within their own lifetime (and still be alive to receive the Nobel Prize for their discovery). DUNE detectors will monitor 40,000 tons of liquid argon.

    FNAL DUNE Argon tank at SURF

    Each atom of argon contains 18 protons. If one out of this incredible number of protons decays during DUNE’s lifetime, it will show up in DUNE’s data.

    “If a proton decay is discovered, it is a revolutionary discovery—a once-in-a-generation discovery,” said Jung, who has played various leadership roles in DUNE.

    An invisible neutrino

    Neutrinos are subatomic particles; waiflike, abundant and neutral, they hardly interact with normal matter at all. DUNE is designed to monitor how neutrinos oscillate, or change between three different types of neutrino, as they stream through the Earth. But DUNE could also see something extra hidden in its data.

    “In the Standard Model, there are three types of neutrino: the electron neutrino, the muon neutrino and the tau neutrino. But why is there not a fourth generation? Why not five? What stops it at three? That is not known,” Jung said.

    There are subatomic hints of another type of neutrino, called a sterile neutrino, that interacts even less than the other known types. If it exists, the only way it could be measured is the way in which it joins the oscillation pattern of neutrinos, disrupting the pattern physicists expect to see.

    4
    There are subatomic hints of another type of neutrino, called a sterile neutrino, that interacts even less than the other known types. Courtesy Fermilab.

    “If what we see doesn’t match our three-flavor oscillation pattern, it will tell us a lot about what is incomplete about our understanding of the universe,” said Elizabeth Worcester, DUNE physics co-coordinator and physicist at Brookhaven National Laboratory. “It could point to the existence of sterile neutrinos, a new interaction or even some other crazy thing we haven’t thought of yet. It would take some untangling to understand what the data is really telling us.”

    Investigating dark matter

    Dark matter is a mysterious, invisible source of matter responsible for holding vast galaxies together. Although not directly tied to theories of unification, the long-standing mystery of dark matter transcends the Standard Model. And depending on its true characteristics, DUNE could be the first to detect it.

    “Dark matter is an enormous question in our field,” said Feng, who has worked on a specific dark matter theory, called WIMP theory, for 22 years. “There is a lot of interesting creative work being done in theory, but hints from experiments like DUNE would be really helpful.”

    According to WIMP theory, dark matter is composed of weakly interacting, massive particles (WIMPs). If these particles exist, some of them are expected to pass through the Sun. There, they would interact with other particles, losing energy and sinking into the Sun’s core. Over time, enough WIMPs would gravitate toward the Sun’s core that they would annihilate with each other and release high-energy neutrinos in all directions. As you might guess, DUNE would be ready to detect these neutrinos. Researchers could reconstruct their trajectory, tracing them back to the Sun and, indirectly, to the WIMPs that produced them.
    ________________________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova


    ________________________________________________

    While Feng hasn’t given up on WIMPs, he has recently started working on another dark matter theory that involves light dark matter particles. This theory predicts that, in addition to looking for dark matter directly, we could also learn more about dark matter through so-called “mediator particles.”

    “If you imagine we could talk to dark matter on the phone, mediator particles would be the wire that connects us to it,” Feng said. If this theory is accurate, mediator particles could potentially be created as by-products in Fermilab’s particle accelerator and show themselves in one of DUNE’s detectors.

    Whatever its true characteristics, dark matter might reveal itself in DUNE, offering clues to yet another universe-sized mystery.

    Looking where the light is

    “There are other interactions beyond the Standard Model that DUNE could be sensitive to,” Worcester said. “Spontaneous neutron-antineutron oscillation, nonstandard interactions, exotic things like Lorentz violation, which would mean that almost all theory is broken.” The list goes on. “If it feels like a grab bag, that’s because it is.”

    Worcester likens DUNE’s multifaceted approach to the streetlamp effect. If you drop your keys on a dark street, you look under the streetlamp to find them. They may not be within the beam of light created by the streetlamp, but you have no hope of finding the keys in the darkness. So, you look where the light is.

    When researchers are attempting to look beyond what is known, advanced experiments like DUNE become their streetlamps, casting puddles of light onto unfamiliar physics.

    “It could be that some answers are still in the dark, but if we keep creating sophisticated experiments, we’ll find them,” Worcester said.

    So, why DUNE? Amidst its search for the origin of matter and supernovas on the galactic horizon, DUNE will also shine a bright light on physics beyond the Standard Model.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

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

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

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

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

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

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

    LBNL LZ project at SURF, Lead, SD, USA, will replace LUX 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.

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


    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.

    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 8:34 am on May 19, 2020 Permalink | Reply
    Tags: , Neutrinos,   

    From Sanford Underground Research Facility: “Why DUNE? Exploring supernovas, neutron stars and black holes” 

    SURF logo

    From Sanford Underground Research Facility


    Homestake Mining Company

    May 18, 2020
    Erin Lorraine Broberg

    Part II in our series exploring the science goals of the international Deep Underground Neutrino Experiment.

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


    Surf-Dune/LBNF Caverns at Sanford


    FNAL DUNE Argon tank at SURF

    1
    The Deep Underground Neutrino Experiment (DUNE) could help us learn more about supernovas, neutron stars and black holes.
    Courtesy Fermilab.

    Throughout the 13.8-billion-year lifetime of the universe, countless generations of stars have slowly warmed, forged elements in their core and, eventually, perished. The largest of these stars die in brilliant supernova explosions that hurl elements into deep space. Over the ages, the broiling clouds of ancient supernovas coalesced to form galaxies, new stars and even our own solar system.

    Astronomers have long studied this rarely witnessed process. In the twentieth century, particle physicists discovered that neutrinos, lightweight particles produced in massive quantities in supernovas, are the first to evacuate during supernova explosions.

    The Deep Underground Neutrino Experiment’s (DUNE) Far Detector at Sanford Underground Research Facility (Sanford Lab) will be monitoring a beam of neutrinos created 800 miles away at the Department of Energy’s Fermilab, the host laboratory for DUNE. The Far Detector will also be tuned to see any neutrinos streaming from a nearby supernova. Such neutrino interactions could give researchers insight into one of the explosive processes that formed the elements in our solar system, our planet and even our bones.

    The dawn of neutrino astronomy

    In 1987, astrophysicists witnessed the death throes of a star. For the first time since the dawn of modern science, researchers observed a core-collapse supernova in a nearby satellite of the Milky Way. From this massive stellar explosion, underground labs in the United States, Russia and Japan detected a grand total of about 25 neutrinos. They named it Supernova (SN) 1987A.

    3
    SN1987A, a supernova first detected in 1987, is at the center of an image taken by the Hubble Space Telescope in January. Photo courtesy European Space Agency/NASA.

    “I recall hearing a physicist once say that the name SN 1987A hints at the eternal optimism of scientists,” said Mark Hanhardt, astrophysicist and support scientist at Sanford Lab. “This was the closest supernova in nearly 400 years, and astronomers called it 1987A—just to make sure we’d have room for a 1987B later that year.”

    Other supernovas continued to explode in space that year, but B, C and D never made headlines—they were too distant to provide an observable neutrino flux in underground detectors. Still, the handful of neutrinos detected from 1987A provided enough data to keep astrophysicists busy for decades. Hundreds of physicists have scrutinized these few of subatomic interactions since, trying to make sense of complex supernovas.

    If one of the billions of stars in our galaxy goes supernova during DUNE’s lifetime, however, DUNE will see more than a handful of neutrinos—it will see thousands.

    “I like to joke that if DUNE sees a supernova in our galaxy, we are all going to suddenly become astrophysicists,” said Ryan Patterson, DUNE physics co-coordinator and professor of physics at the California Institute of Technology (Caltech). “The data will be so rich that everyone is going to want to study it. It’s that fascinating.”

    Catastrophe in space, neutrino signals on Earth

    A core-collapse supernova occurs when massive stars—at least 8 times larger than the sun— reach the end of their lives. These massive stars are element-forgers, creating lightweight elements like hydrogen and helium first, then working their way up the periodic table to form heavier and heavier elements like iron.

    For most of its life, the pull of a star’s gravity is balanced by the energy created through nuclear fusion. Toward the end of its life, the scales tip. The star’s own gravitational pull becomes stronger than the energy it creates from fusion and it collapses under its own weight.

    “It becomes tremendously dense—all the falling matter from an enormous star is compacted to a radius of 10 kilometers, the size of a small city,” said Kate Scholberg, co-convener of DUNE’s supernova working group and professor of physics at Duke University.

    During this catastrophic scrunch, physics get strange. Magnetic fields increase exponentially, particles are created en masse, and matter becomes so dense that even neutrinos begin to interact with other neutrinos.

    “Neutrinos are actually trapped inside the star for less than a second, which is mind blowing if you’re a neutrino physicist,” Scholberg said. “Neutrinos interact so rarely; you can’t imagine anything being able to stop all of them at once.”

    Next, the entire mass of the star rebounds. A massive shockwave propagates outward, tearing the star apart and tossing elements into the universe. Neutrinos escape this dense cloud first, scattering in all directions and whisking away nearly all of the supernova’s energy.

    4
    This Hubble image of Supernova 1987A shows the brightening ring of supernova debris. The closest supernova seen in almost 400 years, Supernova 1987A is located in the Large Magellanic Cloud. Photo courtesy NASA, ESA and Pete Challis (Harvard-Smithsonian Center for Astrophysics).

    “More than 99 percent of the supernova’s energy escapes the star in the form of neutrinos,” Scholberg said.

    In the wake of the neutrino exit, the shockwave continues to pass through the star, causing the star to brighten and create exotic new elements. Gold, silver, platinum and uranium are created here, just in time to be tossed deep into space. Ultimately, whatever mass remains will collapse once more, settling into either a stable neutron star or a black hole, an object so dense that it swallows everything within its event horizon.

    Despite this astonishing description, the details of what happens during a supernova explosion are still quite fuzzy to astronomers. When the resulting torrent of neutrinos passes through DUNE’s detectors, the traces they leave will shed light on supernovas, the formation of neutron stars and black holes, and even neutrinos themselves.

    Harbingers of the supernova

    Because neutrinos escape first and travel just shy of the speed of light, they will wash through DUNE’s detectors hours before light from the supernova becomes visible on Earth. Thus, neutrinos act as an early detection system, alerting astronomers to search the skies for the telltale brightening of a dying star. Adding to data from neutrino experiments and telescopes, gravitational wave detectors also expect to detect ripples in spacetime from the event.

    “If we could combine the detection of neutrinos, light and gravitational waves—all this multi-messenger information from different experiments would be incredibly rich,” said Inés Gil-Botella, co-convener DUNE’s supernova working group and senior scientist at CIEMAT national lab in Spain.

    Neutrinos can also tell researchers a lot about what happens after they leave the re-collapsing star. If the supernova settles back into a neutron star, researchers can count on a steady 10-second stream of neutrinos. However, if a black hole forms, its gravity will suck back all the neutrinos that were still within the event horizon.

    “That would be the coolest thing to see—the birth of the black hole,” said Scholberg. “You’d see this really intense flux of neutrinos and then—bam! —it would just stop.”

    5
    Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy Messier 87. This long-sought image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. Credit: Event Horizon Telescope Collaboration.

    EHT map

    While neutrinos from a supernova can document the last moments of a star’s life, they will also be studied by researchers who want to know more about neutrinos themselves.

    “You can think of supernovas as special laboratories,” Gil-Botella said. “The conditions are so unique—the temperatures and densities are so high— that we could never replicate them on earth.”

    Seeing how neutrinos interact and react in this distinctive environment could tell physicists things about their nature that they would never see in ambient neutrinos or even DUNE’s beamline. The way neutrinos flee the supernova, how quickly they travel through space and how they oscillate during their trip could shed light on the mass of a neutrino and even provide insight into physics beyond the Standard Model.

    “It’s a virtuous circle,” Scholberg said. “The more we learn about neutrinos from lab experiments, the easier it is to learn about the supernova. The more you know about the nature of a supernova, the easier it is to extract the neutrino properties. Each sphere helps the other.”

    So, why DUNE? Within a mere 10 seconds, DUNE’s detectors could gather enough data to transform our understanding of the death throes of a star. The data would take years to untangle, but within it lies answers to the explosive evolution of our universe.

    Even so, there’s even more to DUNE than searching for the origin of matter and peering into exploding stars. Stay tuned for part III of our series of stories about the science of DUNE.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

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

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

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

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

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

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

    LBNL LZ project at SURF, Lead, SD, USA, will replace LUX 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.

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


    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.

    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 10:06 am on May 14, 2020 Permalink | Reply
    Tags: , Neutrinos,   

    From Moscow Institute of Physics and Technology via phys.org: “Where neutrinos come from” 

    1

    From Moscow Institute of Physics and Technology

    via


    phys.org

    May 13, 2020

    1
    The Russian RATAN-600 telescope helps to understand the origin of cosmic neutrinos Credit: Daria Sokol/MIPT

    3
    RATAN-600 ~ The World’s Largest Radio Telescope in Russia

    Russian astrophysicists have come close to determining the origin of high-energy neutrinos from space. The team compared data on the elusive particles gathered by the Antarctic neutrino observatory IceCube and on long electromagnetic waves measured by radio telescopes. Cosmic neutrinos turned out to be linked to flares at the centers of distant active galaxies, which are believed to host supermassive black holes. As matter falls toward the black hole, some of it is accelerated and ejected into space, giving rise to neutrinos that then coast along through the universe at nearly the speed of light.

    The study is published in The Astrophysical Journal.

    Neutrinos are mysterious particles so tiny that researchers do not even know their mass. They pass effortlessly through objects, people and even entire planets. High-energy neutrinos are created when protons accelerate to nearly the speed of light.

    The Russian astrophysicists focused on the origins of ultra-high-energy neutrinos at 200 trillion electron volts or more. The team compared the measurements of the IceCube facility, buried in the Antarctic ice, with a large number of radio observations. The elusive particles were found to emerge during radio frequency flares at the centers of quasars.

    Quasars are sources of radiation at the centers of some galaxies. They consist of a massive black hole that consumes matter floating in a disk around it and spews out extremely powerful jets of ultrahot gas.

    “Our findings indicate that high-energy neutrinos are born in active galactic nuclei, particularly during radio flares. Since both the neutrinos and the radio waves travel at the speed of light, they reach the Earth simultaneously,” said the study’s first author Alexander Plavin.

    Plavin is a Ph.D. student at Lebedev Physical Institute of the Russian Academy of Sciences (RAS) and the Moscow Institute of Physics and Technology. As such, he is one of the few young researchers to obtain results of that caliber at the outset of their scientific career.

    Neutrinos come from where no one had expected

    After analyzing around 50 neutrino events detected by IceCube, the team showed that these particles come from bright quasars seen by a network of radio telescopes around the planet.

    U Wisconsin ICECUBE neutrino detector at the South Pole

    The network uses the most precise method of observing distant objects in the radio band: very long baseline interferometry. This method in essence creates a giant telescope by placing many antennas around the globe. Among the largest elements of this network is the 100-meter telescope of the Max Planck Society in Effelsberg.

    MPIFR/Effelsberg Radio Telescope, in the Ahrgebirge (part of the Eifel) in Bad Münstereifel, Germany

    Additionally, the team hypothesized that the neutrinos emerged during radio flares. To test this idea, the physicists studied the data of the Russian RATAN-600 radio telescope in the North Caucasus. The hypothesis proved highly plausible despite the common assumption that high-energy neutrinos are supposed to originate together with gamma rays.

    “Previous research on high-energy neutrino origins had sought their source right ‘under the spotlight.” We thought we would test an unconventional idea, though with little hope of success. But we got lucky,” says Yuri Kovalev from Lebedev Institute, MIPT, and the Max Planck Institute for Radio Astronomy. “The data from years of observations on international radio telescope arrays enabled that very exciting finding, and the radio band turned out to be crucial in pinning down neutrino origins.”

    “At first, the results seemed too good to be true, but after carefully reanalyzing the data, we confirmed that the neutrino events were clearly associated with the signals picked up by radio telescopes,” Sergey Troitsky from the Institute for Nuclear Research of RAS added. “We checked that association based on the data of years-long observations of the RATAN telescope of the RAS Special Astrophysical Observatory, and the probability of the results being random is only 0.2%. This is quite a success for neutrino astrophysics, and our discovery now calls for theoretical explanations.”

    The team intends to recheck the findings and figure out the mechanism behind the neutrino origins in quasars using the data from Baikal-GVD, an underwater neutrino detector in Lake Baikal, which is in the final stages of construction and already partly operational. The so-called Cherenkov detectors, used to spot neutrinos—including IceCube and Baikal-GVD—rely on a large mass of water or ice as a means of both maximizing the number of neutrino events and preventing the sensors from accidental firing. Of course, continued observations of distant galaxies with radio telescopes are equally crucial to this task.

    See the full article here.

     
  • richardmitnick 11:40 am on May 12, 2020 Permalink | Reply
    Tags: "Why DUNE? Searching for the origin of matter", , , , Neutrinos,   

    From Sanford Underground Research Facility: “Why DUNE? Searching for the origin of matter” 

    SURF logo

    From Sanford Underground Research Facility


    Homestake Mining Company

    May 11, 2020
    Erin Lorraine Broberg

    1
    DUNE science goal icon: Origin of matter.Credit: Fermilab

    Why does matter exist? It may seem like a strange question, but according to current models of the early universe, matter shouldn’t exist.

    “According to what we know about the laws of physics, the amount of matter in the universe should be, effectively, zero,” said André de Gouvêa, a theoretical physicist with the DUNE collaboration and professor at Northwestern University.

    In physics, the discrepancy between what we see—a universe filled with galaxies and a planet teeming with life—and what models predict we should see—absolutely nothing—is called the “matter-antimatter asymmetry problem.” The international Deep Underground Neutrino Experiment, or DUNE, hosted by the Department of Energy’s Fermilab and to be built at Fermilab and Sanford Lab, seeks to solve this problem, which has dogged physicists for nearly a century.

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


    The Deep Underground Neutrino Experiment will measure neutrino oscillations by studying a neutrino that will be sent from Fermilab to the DUNE detectors at the Sanford Underground Neutrino Facility. The experiment will use a muon neutrino beam created at Fermilab’s Long-Baseline Neutrino Facility and send it 800 miles/1300 kilometers straight through the earth to South Dakota. By the time the neutrinos arrive in South Dakota, only a small fraction of neutrinos will be detected as muon neutrinos. Most neutrinos will interact as electron and tau neutrinos. Graphic courtesy Fermilab

    A universe-sized problem

    Despite what the models predict, we find ourselves amidst a universe replete with matter. Everything we see around us is made from just a few types of fundamental particles. Combined, they form protons and neutrons which join up with electrons to form atoms, which in turn bind to make molecules, building ever larger.

    But these key ingredients are only half the story.

    In the 1930s, physicists discovered “antiparticles” that mirror the fundamental particles. Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Just like matter particles, antimatter particles could combine to build bigger and bigger units of antimatter—if they ever survived long enough do to so.

    Although matter and antimatter particles are nearly indistinguishable, the two forms do not coexist peacefully. When antimatter comes into contact with regular matter, particles and antiparticles immediately annihilate, leaving leaving pure energy in their wake.

    This complete, mutual annihilation is the impetus of the matter-antimatter asymmetry problem. Our current models dictate that the Big Bang created equal parts matter and antimatter. Within a second, all the matter and antimatter should have met and annihilated, leaving behind a universe with nothing but energy in the form of light.

    2
    Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Graphic courtesy Fermilab

    “The problem is, if we take our favorite model and calculate the evolution of the universe, we get a prediction that is completely off,” de Gouvêa said. “There should not be any matter in the universe we live in today.”

    We know, of course, that this didn’t happen. We live in a matter-dominated universe with swirling galaxies, innumerable stars and at least one life-sustaining planet. Somehow, about one billionth of the total amount of matter created in the Big Bang managed to evade annihilation and fill the universe with the matter we see today. Thus, the matter-antimatter asymmetry problem.

    Physicists believe there is an undiscovered mechanism, hidden in the wrinkles of nature’s laws, that gave matter an initial advantage over antimatter. And for nearly a century, they’ve been trying to pinpoint it.

    A crack in nature’s symmetry

    Because matter and antimatter are mirror images of each other, physicists assumed that the laws of nature applied to both matter particles and antimatter particles in the exact same way. In physics, this type of equality is called a “symmetry.”

    According to this idea, weak and strong forces should bind particles and antiparticles without discrimination. Gravity should pull on antimatter with the same force it exerts on matter. Magnets should attract oppositely charged particles and antiparticles with the same gusto. In fact, an entire universe made of antimatter should look identical to the one we live in today.

    This assumption of a perfect symmetry among the fundamental building blocks of the universe held true until the 1960s, when James Cronin and Val Fitch made the shocking discovery that, in a very specific case, the universe treats matter slightly different than antimatter.

    Their Nobel Prize-winning experiment examined the way that quarks (fundamental particles that make up protons and neutrons) and antiquarks (their corresponding antiparticles) interacted with the weak force. Rather than treating quarks and antiquarks the same way, the weak force favored quarks in an infamous violation of what is called the Charge Parity (CP) symmetry.

    In other words, the universe had revealed a slight preference for matter over antimatter.

    3
    CP violation experiment: In 1963, a beam from BNL’s Alternating Gradient Synchrotron and the pictured detectors salvaged from the Cosmotron were used to prove the violation of conjugation (C) and parity (P) – winning the Nobel Prize in physics for Princeton University physicists James Cronin and Val Fitch. Photo courtesy Brookhaven National Laboratory.

    This discovery stunned the particle physics community. In the decades that followed, researchers continued to make precision measurements of these decays, combing their data for new physics that might be lurking within this phenomenon. Thirty years after Cronin and Fitch’s discovery, Elizabeth Worcester was making such measurements at Fermilab’s Tevatron with the KTeV experiment.

    “In the 1990s, we were studying the same decays in which CP violation was first observed,” said Worcester, who is now a DUNE physcis co-coordinator and physicist at Brookhaven National Laboratory.

    This glitch in the laws of nature specifically caught the attention of physicists studying the imbalance of matter and antimatter in the universe. Was this violation of CP symmetry the mechanism that allowed some matter to escape annihilation after the Big Bang?

    Subsequent experiments combined with more and more sophisticated calculations demonstrated that nature’s unequal treatment of quarks and antiquarks is not quite big enough to account for the gaping discrepancy we see today.

    However, scientists think the existence of CP violation is a major clue.

    “This violation could mean there is something very fundamental about the laws of nature that we are missing,” de Gouvêa said.

    As soon as Cronin and Fitch made their discovery, physicists began to wonder if other fundamental particles broke the same symmetry. Perhaps multiple sources of CP violation, when combined, could explain how so much matter escaped annihilation in the early universe.

    By finding another, even bigger crack in this symmetry, physicists aim to prove that the universe has an overarching preference for matter, making our current universe possible.

    A ghost-like candidate

    If quarks didn’t provide enough CP violation in the early universe, could another category of elementary particles known as neutrinos have provided another way to favor matter over antimatter?

    “If you look at everything that we’ve learned about neutrinos so far, it indicates that CP could be violated in the neutrino sector,” de Gouvêa said. “There is no specific reason to expect it not to be violated.”

    Neutrinos are extremely challenging to work with. Trillions of these particles pass through you each second. Their miniscule mass and neutral charge make them almost impossible to detect. Building an experiment to test whether these ghost-like particles violate the CP symmetry is even more ambitious.

    “The reason we don’t know if neutrinos violate CP symmetry is purely an experimental issue,” said Ryan Patterson, DUNE physics co-coordinator and professor of physics at the California Institute of Technology (Caltech). “Neutrinos could violate CP a lot, but we don’t know yet because the experiments up to this point haven’t been sensitive enough.”

    One peculiar property of neutrinos, however, makes the DUNE experiment possible. As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation.

    4
    As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation. Graphic courtesy Fermilab

    “In regard to neutrinos, we only have one realistic way of measuring CP violation: it will show itself in the way neutrinos oscillate between flavors,” de Gouvêa said.

    In principle, the measurement is quite simple, according to de Gouvêa.

    “You simply compare a matter process with an antimatter process, and then you ask if they agree,” de Gouvêa said. To measure the CP violation, researchers must compare the oscillations of neutrinos with the oscillations of antineutrinos. If there is a discrepancy in the way they oscillate over a distance, then neutrinos break the symmetry.

    The difficult part of the experiment is that neutrino oscillations occur over hundreds of miles. To measure a deviation or discrepancy, researchers would need… well, they would need to build a long-baseline neutrino facility.

    Are neutrinos the reason we exist?

    The particulars of this universe-sized mystery have guided the design of the aptly named Long-Baseline Neutrino Facility (LBNF), which will house the Deep Underground Neutrino Experiment. Stretching across the Midwest, with infrastructure located at Fermilab in Batavia, Illinois and at Sanford Lab in Lead, South Dakota, the facility allows researchers to measure just how neutrinos and antineutrinos oscillate over long distances.

    It works like this: a particle accelerator will generate intense beams of neutrinos and antineutrinos at Fermilab. The beams will travel 800 miles straight through rock and earth – no tunnel needed – to enormous particle detectors located deep underground at Sanford Underground Research Facility (Sanford Lab), where 4,850 feet of rock overburden shield the detectors from unwanted background signals.

    During their trip through the Earth’s crust—which takes just four milliseconds—the neutrinos and antineutrinos will oscillate, changing from one flavor into another. Conveniently, the distance between Fermilab and Sanford Lab is ideal for this measurement; by the time the particles arrive at Sanford Lab, their oscillations will be at their peak.

    “To get the best measurement, we put the detectors right where we expect the oscillation to be maximal,” Patterson said.

    When the beam reaches Sanford Lab, some of the neutrinos and antineutrinos will collide with argon atoms inside the detectors. These collisions result in unique signals. By measuring and comparing hundreds of these signals, researchers will be able to tell if neutrinos and antineutrinos oscillate in different ways – the sure-tell sign of CP symmetry violation – and if so, by how much.

    “I think what the neutrinos are going to tell us could change our understanding of nature in a very interesting way,” de Gouvêa said.

    So, why DUNE? In a nutshell, it could help scientists answer one of the big unsolved questions in science and give all of us an answer to the reason we—and everything else in the universe—exists.

    That, however, is only part of the story. Stay tuned for part II of our series of stories about the science of DUNE.

    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.

    LBNL LZ project at SURF, Lead, SD, USA, will replace LUX 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.

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


    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.

    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 10:27 am on May 12, 2020 Permalink | Reply
    Tags: , , , , , , Neutrinos,   

    From Lawrence Berkeley National Lab: “Berkeley Lab COVID-19 related research and additional information. News Center CUORE Underground Experiment in Italy Carries on Despite Pandemic” 


    From Lawrence Berkeley National Lab

    May 12, 2020
    Glenn Roberts Jr.
    (510) 520-0843
    geroberts@lbl.gov

    Laura Marini, a postdoctoral researcher at UC Berkeley and a Berkeley Lab affiliate who serves as a run coordinator for the underground CUORE experiment, shares her experiences of working on CUORE and living near Gran Sasso during the COVID-19 pandemic. (Credit: Marilyn Sargent/Berkeley Lab)

    Note: This is the first part in a recurring series highlighting Berkeley Lab’s ongoing work in international physics collaborations during the pandemic.

    As the COVID-19 outbreak took hold in Italy, researchers working on a nuclear physics experiment called CUORE at an underground laboratory in central Italy scrambled to keep the ultrasensitive experiment running and launch new tools and rules for remote operations.

    This Cryogenic Underground Observatory for Rare Events experiment – designed to find a never-before-seen process involving ghostly particles known as neutrinos, to explain why matter won out over antimatter in our universe, and to also hunt for signs of mysterious dark matter – is carrying on with its data-taking uninterrupted while some other projects and experiments around the globe have been put on hold.

    Finding evidence for these rare processes requires long periods of data collection – and a lot of patience. CUORE has been collecting data since May 2017, and after upgrade efforts in 2018 and 2019 the experiment has been running continuously.

    Before the pandemic hit there were already tools in place that stabilized the extreme cooling required for CUORE’s detectors and provided some remote controls and monitoring of CUORE systems, noted Yury Kolomensky, senior faculty scientist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the U.S. spokesperson for CUORE.

    The rapid global spread of the disease, and related restrictions on access to the CUORE experiment at Gran Sasso National Laboratory (Laboratori Nazionali del Gran Sasso, or LNGS, operated by the Italian Nuclear Physics Institute, INFN) in central Italy, prompted CUORE leadership and researchers – working in three continents – to act quickly to ramp up the remote controls to prepare for an extended period with only limited access to the experiment.

    CUORE experiment,at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) in located in the Abruzzo region of central Italy,a search for neutrinoless double beta decay

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

    Just days before the new restrictions went into effect at Gran Sasso, CUORE leadership on March 4 made the decision to rapidly deploy a new remote system and to work out the details of how to best maintain the experiment with limited staffing and with researchers monitoring in different time zones. The new system was fully operational about a week later, and researchers at Berkeley Lab played a role in rolling it out.

    “We were already planning to transition to remote shift operations, whereby a scientist at a home institution would monitor the systems in real time, respond to alarms, and call on-site and on-call personnel in case an emergency intervention is needed,” Kolomensky said, adding, “We were commissioning the system at the time of the outbreak.”

    Brad Welliver, a postdoctoral researcher, served as Berkeley Lab’s lead developer for the new remote monitoring system, and Berkeley Lab staff scientist Brian Fujikawa was the overall project lead for the enhanced remote controls, collectively known as CORC, for CUORE Online/Offline Run Check.

    Fujikawa tested controls for starting and stopping the data collection process, and also performed other electronics testing for the experiment from his home in the San Francisco Bay Area.

    He noted that the system is programmed to send email and voice alarms to the designated on-shift CUORE researcher if something is awry with any CUORE system. “This alarm system is particularly important when operating CUORE remotely,” he said, as in some cases on-site workers may need to visit the experiment promptly to perform repairs or other needed work.

    Development of so-called “slow controls,” which allow researchers to monitor and control CUORE equipment such as pumps and sensors, was led by Joe Johnston at the Massachusetts Institute of Technology.

    “Now we can perform most of the operations from 6,000 miles away,” Kolomensky said.

    And many participants across the collaboration continue to play meaningful roles in the experiment from their homes, from analyzing data and writing papers to participating in long-term planning and remote meetings.

    Despite access restrictions at Gran Sasso, experiments are still accessible for necessary work and checkups. The laboratory remains open in a limited way, and its staff still maintains all of its needed services and equipment, from shuttles to computing services.

    Laura Marini, a postdoctoral researcher at UC Berkeley who serves as a run coordinator for CUORE and is now living near Gran Sasso, is among a handful of CUORE researchers who still routinely visits the lab site.

    “As a run coordinator, I need to make sure that the experiment works fine and the data quality is good,” she said. “Before the pandemic spread, I was going underground maybe not every day, but at least a few times a week.” Now, it can be about once every two weeks.

    Sometimes she is there to carry out simple fixes, like a stuck computer that needs to be restarted, she said. Now, in addition to the requisite hard hat and heavy shoes, Marini – like so many others around the globe who are continuing to work – must wear a mask and gloves to guard against the spread of COVID-19.

    The simple act of driving into the lab site can be complicated, too, she said. “The other day, I had to go underground and the police stopped me. So I had to fill in a paper to declare why I was going underground, the fact that it was needed, and that I was not just wandering around by car,” she said. Restrictions in Italy prevent most types of travel.

    2
    Laura Marini now wears a protective mask and gloves, in addition to a hard hat, during her visits to the CUORE experiment site. (Credit: Gran Sasso National Laboratory – INFN)

    CUORE researchers note that they are fortunate the experiment was already in a state of steady data-taking when the pandemic hit. “There is no need for continuous intervention,” Marini said. “We can do most of our checks by remote.”

    She said she is grateful to be part of an international team that has “worked together on a common goal and continues to do so” despite the present-day challenges.

    Kolomensky noted some of the regular maintenance and upgrades planned for CUORE will be put off as a result of the shelter-in-place restrictions, though there also appears to be an odd benefit of the reduced activity at the Gran Sasso site. “We see an overall reduction in the detector noise, which we attribute to a significantly lower level of activity at the underground lab and less traffic in the highway tunnel,” he said. Researchers are working to verify this.

    CUORE already had systems in place to individually and remotely monitor data-taking by each of the experiment’s 988 detectors. Benjamin Schmidt, a Berkeley Lab postdoctoral researcher, had even developed software that automatically flags periods of “noisy” or poor data-taking captured by CUORE’s array of detectors.

    Kolomensky noted that work on the CORC remote tools is continuing. “As we have gained more experience and discovered issues, improvements and bug fixes have been implemented, and these efforts are still ongoing,” he said.

    CUORE is supported by the U.S. Department of Energy Office of Science, Italy’s National Institute of Nuclear Physics (Instituto Nazionale di Fisica Nucleare, or INFN), and the National Science Foundation (NSF). CUORE collaboration members include: INFN, University of Bologna, University of Genoa, University of Milano-Bicocca, and Sapienza University in Italy; California Polytechnic State University, San Luis Obispo; Berkeley Lab; Lawrence Livermore National Laboratory; Massachusetts Institute of Technology; University of California, Berkeley; University of California, Los Angeles; University of South Carolina; Virginia Polytechnic Institute and State University; and Yale University in the US; Saclay Nuclear Research Center (CEA) and the Irène Joliot-Curie Laboratory (CNRS/IN2P3, Paris Saclay University) in France; and Fudan University and Shanghai Jiao Tong University in China.

    See the full article here .

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    Bringing Science Solutions to the World
    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

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  • richardmitnick 1:53 pm on May 4, 2020 Permalink | Reply
    Tags: , Data onslaught, , , Neutrinos,   

    From Fermi National Accelerator Lab: “DUNE prepares for data onslaught” 

    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.

    May 4, 2020
    Jim Daley

    The international Deep Underground Neutrino Experiment, hosted by Fermilab, will be one of the most ambitious attempts ever made at understanding some of the most fundamental questions about our universe.

    LBNF/DUNE

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA


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


    SURF DUNE LBNF Caverns at Sanford Lab


    FNAL DUNE Argon tank at SURF

    Currently under construction at the Sanford Underground Research Facility in South Dakota, DUNE will provide a massive target for neutrinos. When it’s operational, DUNE will comprise around 70,000 tons of liquid argon — more than enough to fill a dozen Olympic-sized swimming pools — contained in cryogenic tanks nearly a mile underground.

    Neutrinos are ubiquitous. They were formed in the first seconds after the Big Bang, even before atoms could form, and they are constantly being produced by nuclear reactions in stars. When massive stars explode and become supernovae, the vast majority of the energy given off in the blast is released as a burst of neutrinos.

    In the laboratory, scientists use particle accelerators to make neutrinos. In DUNE’s case, Fermilab accelerators will generate the world’s most powerful high-energy neutrino beam, aiming it at the DUNE neutrino detector 800 miles (1,300 kilometers) away in South Dakota.

    When any of these neutrinos — star-born or terrestrial — strikes one of the argon atoms in the DUNE detector, a cascade of particles results. Every time this happens, billions of detector digits are generated, which must be saved and analyzed further by collaborators over the world. The resulting data that will be churned out by the detector will be immense. So, while construction continues in South Dakota, scientists around the world are hard at work developing the computing infrastructure necessary to handle the massive volumes of data the experiment will produce.

    3
    The goal of the DUNE Computing Consortium is to establish a global computing network that can handle the massive data dumps DUNE will produce by distributing them across the grid. Photo: Reidar Hahn, Fermilab

    The first step is ensuring that DUNE is connected to Fermilab with the kind of bandwidth that can carry tens of gigabits of data per second, said Liz Sexton-Kennedy, Fermilab’s chief information officer. As with other aspects of the collaboration, it requires “a well-integrated partnership,” she said. Each neutrino collision in the detector will produce an array of information to be analyzed.

    “When there’s a quantum interaction at the center of the detector, that event is physically separate from the next one that happens,” Sexton-Kennedy said. “And those two events can be processed in parallel. So, there has to be something that creates more independence in the computing workflow that can split up the work.”

    Sharing the load

    One way to approach this challenge is by distributing the workflow around the world. Mike Kirby of Fermilab and Andrew McNab of the University of Manchester in the UK are the technical leads of the DUNE Computing Consortium, a collective effort by members of the DUNE collaboration and computing experts at partner institutions. Their goal is to establish a global computing network that can handle the massive data dumps DUNE will produce by distributing them across the grid.

    “We’re trying to work out a roadmap for DUNE computing in the next 20 years that can do two things,” Kirby said. “One is an event data model,” which means figuring out how to handle the data the detector produces when a neutrino collision occurs, “and the second is coming up with a computing model that can use the conglomerations of computing resources around the world that are being contributed by different institutions, universities and national labs.”

    It’s no small task. The consortium includes dozens of institutions, and the challenge is ensuring the computers and servers at each are orchestrated together so that everyone on the project can carry out their analyses of the data. A basic challenge, for example, is making sure a computer in Switzerland or Brazil recognizes a login from a computer at Fermilab.

    Coordinating computing resources across a distributed grid has been done before, most notably by the Worldwide LHC Computing Grid, which federates the United States’ Open Science Grid and others around the world. But this is the first time an experiment at this scale led by Fermilab has used this distributed approach.

    “Much of the Worldwide LHC Computing Grid design assumes data originates at CERN and that meetings will default to CERN, but as DUNE now has an associate membership of WLCG things are evolving,” said Andrew McNab, DUNE’s international technical lead for computing. “One of the first steps was hosting the monthly WLCG Grid Deployment Board town hall at Fermilab last September, and DUNE computing people are increasingly participating in WLCG’s task forces and working groups.”

    “We’re trying to build on a lot of the infrastructure and software that’s already been developed in conjunction with those two efforts and extend it a little bit for our specific needs,” Kirby said. “It’s a great challenge to coordinate all of the computing around the world. In some sense, we’re kind of blazing a new trail, but in many ways, we are very much reliant on a lot of the tools that were already developed.”

    Supernovae signals

    Another challenge is that DUNE has to organize the data it collects differently from particle accelerator physics experiments.

    “For us, a typical neutrino event from the accelerator beam is going to generate something on the order of six gigabytes of data,” Kirby said. “But if we get a supernova neutrino alert,” in which a neutrino burst from a supernova arrives, signaling the cosmic explosion before light from it arrives at Earth, “a single supernova burst record could be as much as 100 terabytes of data.”

    One terabyte equals one trillion bytes, an amount of data equal to about 330 hours of Netflix movies. Created in a few seconds, that amount of data is a huge challenge because of the computer processing time needed to handle it. DUNE researchers must begin recording data soon after a neutrino alert is triggered, and it adds up quickly. But it will also offer an opportunity to learn about neutrino interactions that take place inside supernovae while they’re exploding.

    McNab said DUNE’s computing requirements are also slightly different because the size of each of the events it will capture is typically 100 times larger than the LHC experiments like ATLAS or CMS.

    “So, the computers need more memory — not 100 times more, because we can be clever about how we use it, but we’re pushing the envelope certainly,” McNab said. “And that’s before we even start talking about the huge events if we see a supernova.”

    Georgia Karagiorgi, a physicist at Columbia University who leads data selection efforts for the DUNE Data Acquisition Consortium, said a nearby supernova will generate up to thousands of interactions in the DUNE detector.

    “That will allow us to answer questions we have about supernova dynamics and about the properties of neutrinos themselves,” she said.

    To do so, DUNE scientists will have to combine data on the timing of neutrino arrival, their abundance and what kinds of neutrinos are present.

    “If neutrinos have weird, new types of interactions as they’re propagating through the supernova during the explosion, we might expect modifications to the energy distribution of those neutrinos as a function of time” as they are picked up by the detector, Karagiorgi said. “That goes hand-in-hand with very detailed, and also quite computationally intensive, simulations, with different theoretical assumptions going into them, to actually be able to extract our science. We need both the theoretical simulations and the actual data to make progress.”

    Gathering that data is a huge endeavor. When a supernova event occurs, “we read out our far-detector modules for about 100 seconds continuously,” Kirby said.

    Because the scientists don’t know when a supernova will happen, they have to start collecting data as soon as an alert occurs and could be waiting for 30 seconds or longer for the neutrino burst to conclude. All the while, data could be piling up.

    To prevent too much buildup, Kirby said, the experiment will use an approach called a circular buffer, in which memory that doesn’t include neutrino hits is reused, not unlike rewinding and recording over the tape in a video cassette.

    McNab said the supernovae aspect of DUNE is also presenting new opportunities for computing collaboration.

    “I’m a particle physicist by training, and one of my favorite aspects about working on this project is that way that it connects to other scientific disciplines, particularly astronomy,” he said. In the UK, particle physics and astronomy computing are collectively providing support for DUNE, the Vera C. Rubin Observatory Legacy Survey of Space and Time, and the Square Kilometer Array radio telescopes on the same computers. “And then we have the science aspect that, if we do see a supernova, then we will hopefully be viewing it with multiple wavelengths using these different instruments. DUNE provides an excellent pathfinder for the computing, because we already have real data coming from DUNE’s prototype detectors that needs to be processed.”

    Kirby said that the computing effort is leading to exciting new developments in applications on novel architectures, artificial intelligence and machine learning on diverse computer platforms.

    “In the past, we’ve focused on doing all of our data processing and analysis on CPUs and standard Intel and PC processors,” he said. “But with the rise of GPUs [graphics processing units] and other computing hardware accelerators such as FPGAs [field-programmable gate arrays] and ASICs [application-specific integrated circuits], software has been written specifically for those accelerators. That really has changed what’s possible in terms of event identification algorithms.”

    These technologies are already in use for the on-site data acquisition system in reducing the terabytes per second generated by the detectors down to the gigabytes per second transferred offline. The challenge that remains for offline is figuring out how to centrally manage these applications across the entire collaboration and get answers back from distributed centers across the grid.

    “How do we stitch all of that together to make a cohesive computing model that gets us to physics as fast as possible?” Kirby said. “That’s a really incredible challenge.”

    This work is supported by the Department of Energy Office of Science.

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

    See the full 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 2:46 pm on April 30, 2020 Permalink | Reply
    Tags: "Why the Big Bang Produced Something Rather than Nothing", , , Neutrinos, , , ,   

    From The New York Times: “Why the Big Bang Produced Something Rather than Nothing” 

    From The New York Times

    Published April 15, 2020
    Updated April 27, 2020

    Dennis Overbye

    Scientists on Wednesday announced that they were perhaps one step closer to understanding why the universe contains something rather than nothing.

    1
    The Super-Kamiokande Neutrino Observatory, located more than 3,000 feet below Mount Ikeno near the city of Hida, Japan.Credit…Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo

    Part of the blame, or the glory, they say, may belong to the flimsiest, quirkiest and most elusive elements of nature: neutrinos.

    Standard Model of Particle Physics, Quantum Diaries

    These ghostly subatomic particles stream from the Big Bang, the sun, exploding stars and other cosmic catastrophes, flooding the universe and slipping through walls and our bodies by the billions every second, like moonlight through a screen door.

    Neutrinos are nature’s escape artists. Did they help us slip out of the Big Bang? Perhaps. Recent experiments in Japan have discovered a telltale anomaly in the behavior of neutrinos, and the results suggest that, amid the throes of creation and annihilation in the first moments of the universe, these particles could have tipped the balance between matter and its evil-twin opposite, antimatter.

    As a result, a universe that started out with a clean balance sheet — equal amounts of matter and antimatter — wound up with an excess of matter: stars, black holes, oceans and us.

    An international team of 500 physicists from 12 countries, known as the T2K Collaboration and led by Atsuko K. Ichikawa of Kyoto University, reported in Nature that they had measured a slight but telling difference between neutrinos and their opposites, antineutrinos.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan

    Although the data is not yet convincing enough to constitute solid proof, physicists and cosmologists are encouraged that the T2K researchers are on the right track.

    “This is the first time we got an indication of the CP violation in neutrinos, never done before,” said Federico Sánchez, a physicist at the University of Geneva and a spokesman for the T2K collaboration, referring to the technical name for the discrepancy between neutrinos and antineutrinos. “Already this is a real landmark.”

    But Dr. Sánchez and others involved cautioned that it is too early to break out the champagne. He pointed out that a discrepancy like this was only one of several conditions that Andrei Sakharov, the Russian physicist and dissident winner of the Nobel Peace Prize in 1975, put forward in 1967 as a solution to the problem of the genesis of matter and its subsequent survival.

    Not all the conditions have been met yet. “This is just one of the ingredients,” Dr. Sánchez said. Nobody knows how much of a discrepancy is needed to solve the matter-antimatter problem. “But clearly this goes in the right direction,” he said.

    In a commentary in Nature, Silvia Pascoli of Durham University in England and Jessica Turner of the Fermi National Accelerator Laboratory in Batavia, Ill., called the measurement “undeniably exciting.”

    “These results could be the first indications of the origin of the matter-antimatter asymmetry in our universe,” they wrote.

    The Japan team estimated the statistical significance of their result as “3-sigma,” meaning that it had one chance in 1,000 of being a fluke. Those odds may sound good, but the standard in physics is 5-sigma, which would mean less than a one-in-a-million chance of being wrong.

    “If this is correct, then neutrinos are central to our existence,” said Michael Turner, a cosmologist now working for the Kavli Foundation and not part of the experiment. But, he added, “this is not the big discovery.”

    Joseph Lykken, deputy director for research at Fermilab, said he was cheered to see a major science result coming out during such an otherwise terrible time.


    “The T2K collaboration has worked really hard and done a great job of getting the most out of their experiment,” he said. “One of the biggest challenges of modern physics is to determine whether neutrinos are the reason that matter got an edge over antimatter in the early universe.”

    We are the beauty mark of the universe

    3
    The Russian physicist Andreï Sakharov at home in Moscow in 1974.Credit…Christian Hirou/Gamma-Rapho, via Getty Images

    In a perfect universe, we would not exist.

    According to the dictates of Einsteinian relativity and the baffling laws of quantum theory, equal numbers of particles and their opposites, antiparticles, should have been created in the Big Bang that set the cosmos in motion. But when matter and antimatter meet, they annihilate each other, producing pure energy. (The concept, among others, is what powers the engines of the Starship Enterprise.) Therefore, the universe should be empty of matter.

    That didn’t happen, quite. Of the original population of protons and electrons in the universe, roughly only one particle in a billion survived the first few seconds of creation. That was enough to populate the skies with stars, planets and us.

    In 1967 Dr. Sakharov laid out a prescription for how matter and antimatter could have survived their mutual destruction pact. One condition is that the laws of nature might not be as symmetrical as physicists like Einstein assumed.

    In a purely symmetrical universe, physics should work the same if all the particles changed their electrical charges from positive to negative or vice versa — and, likewise, if the coordinates of everything were swapped from left to right, as if in a mirror. Violating these conditions — called charge and parity invariance, C and P for short — would cause matter and antimatter to act differently.

    In 1957, Tsung-Dao Lee of Columbia University and Chen Ning Yang, then at Institute for Advanced Study, won the Nobel Prize in Physics for proposing something along these lines. They suggested that certain “weak interactions” might violate the parity rule, and experiments by Chien-Shiung Wu of Columbia (she was not awarded the prize) confirmed the theory. Nature, in some sense, is left-handed.

    In 1964, a group led by James Cronin and Val Fitch, working at the Brookhaven National Laboratory on Long Island, discovered that some particles called kaons violated both the charge and parity conditions, revealing a telltale difference between matter and antimatter. These scientists also won a Nobel.

    Hints of a discrepancy between matter and antimatter have since been found in the behavior of other particles called B mesons, in experiments at CERN and elsewhere.

    “In the larger picture, CP violation is a big deal,” Dr. Turner of the Kavli Foundation said. “It is why we are here!”

    Both kaons and B mesons are made of quarks, the same kinds of particles that make up protons and neutrons, the building blocks of ordinary matter. But so far there is not enough of a violation on the part of quarks, by a factor of a billion, to account for the existence of the universe today.

    Neutrinos could change that. “Many theorists believe that finding CP violation and studying its properties in the neutrino sector could be important for understanding one of the great cosmological mysteries,” said Guy Wilkinson, a physicist at Oxford who works on CERN’s LHCb experiment, which is devoted to the antimatter problem.

    CERN/LHCb detector

    Chief among those mysteries, he said: “Why didn’t all matter and antimatter annihilate in the Big Bang?”

    Help from the ghost side

    4
    A bubble chamber showing muon neutrino traces, taken Jan. 16, 1978, at the Fermi National Accelerator Laboratory outside Chicago.Credit…Fermilab/Science Source

    Neutrinos would seem to be the flimsiest excuse on which to base our existence — “the most tiny quantity of reality ever imagined by a human being,” a phrase ascribed to Frederick Reines, of the University of California, Irvine, who discovered neutrinos.

    They entered the world stage in 1930, when the theorist Wolfgang Pauli postulated their existence to explain the small amount of energy that goes missing when radioactive decays spit out an electron. Enrico Fermi, the Italian physicist, gave them their name, “little neutral one,” referring to their lack of an electrical charge. In 1955 Dr. Reines discovered them emanating from a nuclear reactor.; he eventually won a Nobel Prize.

    Second to photons, which compose electromagnetic radiation, neutrinos are the most plentiful subatomic particles in the universe, famed for their ability to waft through ordinary matter like ghosts through a wall. They are so light that they have yet to be reliably weighed.

    But that is just the beginning of their ephemeral magic. In 1936, physicists discovered a heavier version of the electron, called a muon; this shattered their assumption that they knew all the elementary particles. “Who ordered that?” the theorist I.I. Rabi quipped. Further complicating the cosmic bookkeeping, the muon also came with its own associated neutrino, called the muon neutrino, discovered in 1962. That led to another Nobel.

    Another even heavier variation on the electron, called the tau, was discovered by Martin Perl and his collaborators in experiments at the Stanford Linear Accelerator Center in the 1970s. Dr. Perl shared the Nobel in 1995 with Dr. Reines.


    SLAC National Accelerator Lab

    Physicists have since learned that every neutrino is a blend of three versions, each of which is paired with a different type of electron: the ordinary electron that powers our lights and devices; the muon, which is fatter; and, the tau, which is fatter still. Nobody really knows how these all fit together.

    Adding to the mystery, as neutrinos travel about on their ineffable trajectories, they oscillate between their different forms “like a cat turning into a dog,” Dr. Reines once said. That finding was also rewarded with a Nobel. An electron neutrino that sets out on a journey, perhaps from the center of the sun, can turn into a muon neutrino or a tau neutrino by the time it hits Earth.

    By the laws of symmetry, antineutrinos should behave the same way. But do they? Apparently not quite. And on that question may hang a tale of cosmic proportions.

    Test-driving neutrinos

    5
    A mock-up of the more than 13,000 photomultiplier tubes inside the Super-Kamiokande neutrino detector.Credit…Enrico Sacchetti/Science Source

    The T2K experiment, which stands for Tokai to Kamioka, is designed to take advantage of these neutrino oscillations as it looks for a discrepancy between matter and antimatter. Or in this case, between muon neutrinos and muon antineutrinos.

    Since 2014, beams of both particles have been generated at the J-PARC laboratory in Tokai, on the east coast of Japan, and sent 180 miles through the earth to Kamioka, in the mountains of western Japan.

    There they are caught (some of them, anyway) by the Super-Kamiokande neutrino detector, a giant underground tank containing 50,000 tons of very pure water. The tank is lined with 13,000 photomultiplier tubes, which detect brief flashes of light when neutrinos speed through the tank.

    A predecessor to this tank made history on Feb. 23, 1987, when it detected 11 neutrinos streaming from a supernova explosion in the Large Magellanic Cloud, a nearby galaxy.

    The scientists running the T2K experiment alternate between sending muon neutrinos and muon antineutrinos — measuring them as they depart Tokai and then measuring them again on arrival in Kamioka, to see how many have changed into regular old electron neutrinos. If nature and neutrinos are playing by the same old-fashioned symmetrical rules, the same amount of change should appear in both beams.

    On Wednesday, in the abstract to a rather statistically dense paper, the authors concluded: “Our results indicate CP violation in leptons and our method enables sensitive searches for matter-antimatter asymmetry in neutrino oscillations using accelerator-produced neutrino beams.”

    Asked to summarize the result, Dr. Sánchez, a team spokesman, said, “In relative terms more neutrino muons going to neutrino electrons than antineutrino muons going to antineutrino electrons.”

    In other words, matter was winning. This was a step in the right direction but, Dr. Sánchez cautioned, not enough to guarantee victory in the struggle to understand our existence. The big thing, he said, is that the experiment has definitely shown that the neutrinos violate the CP symmetry. Whether they violate it enough is not yet known.

    “For a long time theorists have been discussing if CP violation in neutrinos would be enough,” Dr. Sánchez said. “The general agreement now is that it does not seem to be sufficient. But this is just modeling, and we might be wrong.”

    6
    Workers prepared the Large Hadron Collider at CERN in Switzerland for a shutdown period spanning two years in 2019.Credit…Maximilien Brice and Julien Marius Ordan/CERN, via Science Source

    More and larger experiments are in the works. Among them is the Deep Underground Neutrino Experiment, or DUNE, a collaboration between the U.S. and CERN.

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


    SURF DUNE LBNF Caverns at Sanford Lab


    FNAL DUNE Argon tank at SURF


    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA

    In it, neutrinos will be beamed 800 miles from Fermilab in Illinois to a giant underground detector at the Sanford Underground Research Facility, located in an old gold mine in Lead, S.D., to study how the neutrinos oscillate.

    “The T2K/SuperK result does not remove the need for the future experiments,” Dr. Wilkinson of CERN said. “Rather, it encourages us that we are on the right track and to look forward to the conclusive results that we expect to get from these new projects.”

    He added, “What the Nature paper tells us is that existing experiments have more sensitivity than was previously thought.”

    Dr. Lykken, the deputy director of Fermilab, said, “Now we have a good hint that the DUNE experiment will be able to make a definitive discovery of CP violation relatively soon after it turns on later in this decade.”

    The present situation reminded him of the days a decade ago, when physicists were getting ready to turn on the Large Hadron Collider, CERN’s world-beating $10 billion experiment. There were good hints in the data that the long sought Higgs boson, a quantum ghost of a particle that imbues other particles with mass, might be in reach. “Lo and behold those hints were proven correct at the L.H.C.,” Dr. Lykken said.
    ______________________________________________-
    Other neutrino experiments worthy of mention but skipped in this article:

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


    THE SUDBURY NEUTRINO OBSERVATORY INSTITUTE

    U Wisconsin ICECUBE neutrino detector at the South Pole


    IceCube neutrino detector interior

    Anteres Neutrino Telescope Underwater, a neutrino detector residing 2.5 km under the Mediterranean Sea off the coast of Toulon, France

    INR RAS – Baksan Neutrino Observatory (BNO). The Underground Scintillation Telescope in Baksan Gorge at the Northern Caucasus
    (Kabarda-Balkar Republic)

    KATRIN experiment aims to measure the mass of the neutrino using a huge device called a spectrometer (interior shown)Karlsruhe Institute of Technology, Germany

    Scientists at Fermilab use the MINERvA to make measurements of neutrino interactions that can support the work of other neutrino experiments. Photo Reidar Hahn

    JUNO Neutrino detector, at Kaiping, Jiangmen in Southern China

    Hyper-Kamiokande, a neutrino physics laboratory to be 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.

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

    RENO Experiment. a short baseline reactor neutrino oscillation experiment in South Korea

    See the full article here .

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  • richardmitnick 1:51 pm on April 28, 2020 Permalink | Reply
    Tags: , , , , Neutrinos, SN1987a -"The supernova that keeps on giving",   

    From Symmetry: “The supernova that keeps on giving” 

    Symmetry Mag
    From Symmetry<

    04/28/20
    Shannon Hall

    Supernova 1987A, the closest supernova observed with modern technology, excited the world more than 30 years ago—and it remains an intriguing subject of study even today.

    This is an artist’s impression of the SN 1987A remnant. The image is based on real data and reveals the cold, inner regions of the remnant, in red, where tremendous amounts of dust were detected and imaged by ALMA. This inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

    SN1987a from NASA/ESA Hubble Space Telescope in Jan. 2017 using its Wide Field Camera 3 (WFC3).

    Astronomer Robert Kirshner didn’t believe the news. It was early one morning in February 1987 and a colleague was recounting an unthinkable rumor: A star had exploded in a galaxy next door.

    If it were a prank, it wouldn’t be the first time, so Kirshner wasn’t alone in his skepticism. “It was so unexpected and outrageous that I think for a few hours, we discounted it,” says Stan Woosley, an astronomer at UC Santa Cruz. “But then the messages kept pouring in from all over the world. It was clear that it was real and our lives were all going to change.”

    Although astronomers now spot thousands of supernovae every year, an explosion close enough to be seen with the unaided eye is still a rare event. In fact, the cosmic explosion—dubbed SN1987A or just 87A for short—remains the closest supernova that has been seen in nearly four centuries. Its proximity, plus the use of modern technology, allowed astronomers across the globe to catch an incredible show—one that continues today.

    Supernovae change the fate of entire galaxies, altering the chemical make-up of the interstellar medium and prompting the formation of new stars. They have even had quite an effect on you; the calcium in your bones, the oxygen you breathe and the iron in your hemoglobin were all elements originally unleashed in these massive stellar explosions.

    We know this now. Before 1987, however, much of our understanding of supernovae was based solely on theory. So astronomers around the world scrambled to observe the live event.

    The Russian space station literally rocked back and forth to catch gamma-rays from the explosion. NASA looked for gamma-rays as well, launching high-altitude balloons from Australia to observe them. The Japanese satellite GINGA successfully detected X-rays.

    2
    JAXA GINGA

    Observatories in South Africa, Chile and Australia kept track of the supernova’s light curve. And huge underground detectors in Japan, the United States and Russia detected subatomic particles known as neutrinos.

    “It was a big party, a worldwide party, and stayed that way all year long,” Woosley says.

    But it didn’t end there. Nearly any time a new observatory has come online over the last 33 years, it has swiveled toward the dying explosion. “All the instruments of modern astronomy have been used, by and large,” says Adam Burrows from Princeton University. “There isn’t any class of instrumentation that hasn’t been employed to study 87A.”
    Early insights

    A type II supernova erupts when a heavyweight star runs out of fuel and can no longer support itself against gravity. The bulk of the star comes crashing down toward its core, forcing it to collapse into one of the densest astrophysical objects known, a neutron star. A neutron star squeezes a few solar masses’ worth of star into an orb the size of a city. Meanwhile, the onrush of gas from the rest of the star rebounds against that core, sending a shock wave back toward the surface, which ultimately tears the star apart.

    At least that was the theory. If true, the action would release a huge stream of particles called neutrinos. And because they would pass through the bulk of the star unimpeded, they would arrive at Earth even before the explosion could be seen as a blast of light. (In fact scientists now think that it’s not the bounce that blows up the star, but the neutrinos.)

    To check, scientists began poring over data from the Kamiokande II neutrino detector in Japan as soon as they heard about the eruption.

    Kamiokande-II operated 1985-1990, Japan

    It was painstaking work, but after a few days they spotted nearly a dozen neutrinos that had arrived a few hours before the flash of light—a Nobel Prize-winning discovery that confirmed a neutron star had formed within the blast. “It was the best time so far in my life,” says Masayuki Nakahata, who as a graduate student helped make the detection.

    In total, the Kamiokande II detector in Japan counted 11 neutrinos, the IMB facility in Ohio reported eight and the Baksan Neutrino Observatory in Russia reported five more.

    INR RAS – Baksan Neutrino Observatory (BNO). The Underground Scintillation Telescope in Baksan Gorge at the Northern Caucasus
    (Kabarda-Balkar Republic)

    Neutrino detectors haven’t seen so many particles at once since.

    But while the observation of neutrinos confirmed theories, the observation of the type of star that went supernova went against them. Before SN1987A, textbooks asserted that only puffy red stars known as red supergiants could end their lives in such an explosion. But when scientists peered through past images of the location of the supernova, they found that 87A’s progenitor was a hotter and more compact blue supergiant.

    Astronomers were baffled until the Hubble Space Telescope was launched in 1990. Its early images revealed what other telescopes had only hinted at: a thin ring of glowing gas that encircled the dying ember that 87A left behind, with two fainter rings above and below. These were clues that the star had dumped a lot of gas into space tens of thousands of years before it exploded. A previous outburst, likely from a red supergiant, could have whittled the star down to expose its hotter, bluer innards. Or perhaps two stars had collided together; this would have shed a lot of gas and left behind a hot mess.

    An ongoing event

    To this day, astronomers continue to pivot the Hubble Space Telescope toward SN1987A nearly every year—and for good reason. As the ejecta from the explosion continue to expand outward, they slam into the surrounding medium, lighting up previously unseen material that was emitted in winds before the supernova eruption. “We see something new every time we take an image,” says Josefin Larsson from the KTH Royal Institute of Technology in Sweden.

    They’re not the only ones. The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile recently claimed to have spotted telltale evidence of the “missing” neutron star.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Although the detection of neutrinos indicated that a neutron star had formed within the embers, there was one major snag: Scientists have yet to actually spot the star itself. That’s a problem, given that the neutron star should finally be visible—unless of course there is too much dust surrounding the explosion. “It’s like trying to observe something through a Sahara Desert storm,” Woosley says.

    Finally, there is a hint that the neutron star is there. Using ALMA, Phil Cigan, an astronomer from Cardiff University in the United Kingdom, and his colleagues spotted a small bright patch—affectionally dubbed “the blob”—within the dust of 87A consistent with where scientists predicted the neutron star should be.

    They’re not calling the case closed, though; without being able to see the star directly, no one can prove that the supernova had the predicted effect. “It’s only tantalizing,” Burrows says. “We have to watch for a much longer time to see what’s left emerge.”

    One hypothesis suggests that perhaps a neutron star formed but that it was only short-lived. If more material rained down in the aftermath of the explosion, the star could have gained so much weight that it collapsed further to form a black hole. “Suppose that happened, let’s say, in five days after the explosion,” says Kirshner, who is still at Harvard University and also works full-time as head of science philanthropy for the Gordon and Betty Moore Foundation. “I don’t think we would have any way to know whether that was true or not.”

    Mikako Matsuura, an astronomer who worked on the ALMA observations at Cardiff, agrees that we cannot exclude this hypothesis. But Woosley says he doubts it, arguing that the most natural time to make a black hole would have been within seconds—a hypothesis that’s discounted by the length of the neutrino arrival.

    Whether or not the supernova created a neutron star is “the biggest remaining question in 1987A right now,” Burrows says. And that means that observations won’t stop anytime soon, he says. “It has been a moveable feast—and continues to be.”

    Astronomers hope it’s just a taste of what’s to come. Supernovae likely erupt every 50 years in a galaxy like ours, yet one hasn’t been seen since 1604 (SN1987A was not actually in our galaxy; it was nearby). “We feel as if we’re due for one,” Kirshner says.

    It’s an exciting prospect, given the number of new observatories that have come online in recent years or are scheduled to begin operation soon. The James Webb Space Telescope would be able to image a supernova in the infrared. Radio telescopes like the upcoming Square Kilometer Array in South Africa and ALMA would collect radio waves. The Athena X-ray observatory, which is scheduled to be launched by the European Space Agency in the early 2030s, would image the energetic emission from the supernova.

    ESA/Athena spacecraft depiction

    Gravitational wave facilities such as LIGO in North America, Virgo in Europe and KAGRA in Asia would detect ripples in space-time from such a supernova.

    MIT /Caltech Advanced aLigo


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    KAGRA gravitational wave detector, Kamioka mine in Kamioka-cho, Hida-city, Gifu-prefecture, Japan

    Neutrino facilities such as IceCube at the South Pole, the NOvA detector (and an even larger upcoming project, the DUNE detector) in the United States, and the Super-Kamiokande detector (and an even larger upcoming project, the Hyper-Kamiokande detector) in Japan would be much more sensitive to the influx of neutrinos.

    U Wisconsin ICECUBE neutrino detector at the South Pole

    NOvA Far Detector Block


    FNAL/NOvA experiment map

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


    Surf-Dune/LBNF Caverns at Sanford

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

    Hyper-Kamiokande, a neutrino physics laboratory to be 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.

    Nakahata, who owes his career to 87A and today works as a neutrino physicist, notes that the Hyper-Kamiokande detector alone would be able to witness tens of thousands of the particles in such an instance, a major upgrade from Kamiokande II’s previous record of 11. That would allow scientists to pin down further details behind the neutron star, like how much energy it might emit and the mass of the star itself. While the Hyper-Kamiokande detector would primarily be sensitive to antimatter particles—antineutrinos—the DUNE detector is complementary in that it would primarily be sensitive to matter particles—neutrinos. And additional observations from other detectors across the spectrum would provide even further insights.

    “We should be treated to an incredible show,” Burrows says. “It would dwarf 87A in importance.”

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:13 pm on April 15, 2020 Permalink | Reply
    Tags: , , , Matter and Antmatter, Neutrino physics, Neutrinos, , , ,   

    From University of Colorado Boulder via phys.org: “Why didn’t the universe annihilate itself? Neutrinos may hold the answer” 

    U Colorado

    From University of Colorado Boulder

    via


    phys.org

    April 15, 2020
    Daniel Strain, University of Colorado at Boulder

    1
    Event display for a candidate electron neutrino. Credit: T2K

    Alysia Marino and Eric Zimmerman, physicists at CU Boulder, have been on the hunt for neutrinos for the last two decades.

    That’s no easy feat: Neutrinos are among the most elusive subatomic particles known to science. They don’t have a charge and are so lightweight—each one has a mass many times smaller than the electron—that they interact only on rare occasions with the world around them.

    They may also hold the key to some of physics’ deepest mysteries.

    In a study published today in the journal Nature, Marino, Zimmerman and more than 400 other researchers on an experiment called T2K come closer to answering one of the big ones: Why didn’t the universe annihilate itself in a humungous burst of energy not long after the Big Bang?

    The new research suggests that the answer comes down to a subtle discrepancy in the way that neutrinos and their evil twins, the antineutrinos, behave—one of the first indications that phenomena called matter and antimatter may not be the exact mirror images many scientists believed.

    The group’s findings showcase what scientists can learn by studying these unassuming particles, said Zimmerman, a professor in the Department of Physics.

    “Even 20 years ago, the field of neutrino physics was much smaller than it is today,” he said.

    Marino, an associate professor of physics, agreed. “There’s still a lot we’re trying to understand about how neutrinos interact,” she said.

    Big Bang

    Neutrinos, which weren’t directly detected until the 1950s, are often produced deep within stars and are among the most common particles in the universe. Ever second, trillions of them pass through your body, although few if any will react with a single one of your atoms.

    2
    A graphic showing neutrinos emitted from the sun over a period of 1500 days. Credit: T2K Experiment.

    To understand why this cosmic dandelion fluff is important, it helps to go back to the beginning—the very beginning.

    Based on their calculations, physicists believe that the Big Bang must have created a huge amount of matter alongside an equal quantity of antimatter. These particles behave exactly like, but have opposite charges from, the protons, electrons and all the other matter that makes up everything you can see around you.

    There’s just one problem with that theory: Matter and antimatter obliterate each other on contact.

    “Our universe today is dominated by matter and not antimatter,” Marino said. “So there had to be some process in physics that distinguished matter from antimatter and could have given rise to a small excess of protons or electrons over their antiparticles.”

    Over time, that small excess became a big excess until there was virtually no antimatter left in the cosmos. According to one popular theory, neutrinos underly that discrepancy.

    Zimmerman explained that these subatomic particles come in three different types, which scientists call “flavors,” with unique interactions. They are the muon neutrino, electron neutrino and tau neutrino. You can think of them as the physicist’s Neapolitan ice cream.

    These flavors, however, don’t stay put. They oscillate. If you give them enough time, for example, the odds that a muon neutrino will stay a muon neutrino can shift. Imagine opening your freezer and not knowing whether the vanilla ice cream you left behind will now be chocolate or strawberry, instead.

    But is the same true for antineutrinos? Proponents of the theory of “leptogenesis” argue that if there were even a small difference in how these mirror images behave, it could go a long way toward explaining the imbalance in the universe.

    “The next big step in neutrino physics is to understand whether neutrino oscillations happen at the same rate as antineutrino oscillations,” Zimmerman said.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan

    T2K Experiment, Tokai to Kamioka, Japan

    Traveling Japan

    That, however, means observing neutrinos up close.

    The T2K, or Tokai to Kamioka, Experiment goes to extreme lengths to do just that. In this effort, scientists use a particle accelerator to shoot beams made up of neutrinos from a research site in Tokai, Japan, to detectors in Kamioka—a distance of more than 180 miles or the entire width of Japan’s largest island, Honshu.

    Zimmerman and Marino have both participated in the collaboration since the 2000s. For the last nine years, the duo and their colleagues from around the world have traded off studying beams of muon neutrinos and muon antineutrinos.

    In their most recent study, the researchers hit pay dirt: These bits of matter and antimatter seem to behave differently. Muon neutrinos, Zimmerman said, are more inclined to oscillate into electron neutrinos than their antineutrino counterparts.

    The results come with major caveats. The team’s findings are still quite a bit shy of the physics community’s gold standard for a discovery, a measure of statistical significance called “five-sigma.” The T2K collaboration is already upgrading the experiment so that it can collect more data and faster to reach that mark.

    But, Marino said, the results provide one of the most tantalizing hints to date that some kinds of matter and antimatter may act differently—and not by a trivial amount.

    “To explain the T2K results, the difference needs to be almost the largest amount that you could possibly get” based on theory, she said.

    Marino sees the study as one window to the fascinating world of neutrinos. There are many more pressing questions around these particles, too: How much, for example, does each flavor of neutrino weigh? Are neutrinos, in a really weird twist, actually their own antiparticles? She and Zimmerman are taking part in a second collaboration, an upcoming effort called the Deep Underground Neutrino Experiment (DUNE), that will aid the upgraded T2K in finding those answers.

    “There are still things we’re figuring out because neutrinos are so hard to produce in a lab and require such complicated detectors,” Marino said. “There’s still room for more surprises.”

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Colorado Campus

    As the flagship university of the state of Colorado CU-Boulder is a dynamic community of scholars and learners situated on one of the most spectacular college campuses in the country. As one of 34 U.S. public institutions belonging to the prestigious Association of American Universities (AAU) – and the only member in the Rocky Mountain region – we have a proud tradition of academic excellence, with five Nobel laureates and more than 50 members of prestigious academic academies.

    CU-Boulder has blossomed in size and quality since we opened our doors in 1877 – attracting superb faculty, staff, and students and building strong programs in the sciences, engineering, business, law, arts, humanities, education, music, and many other disciplines.

    Today, with our sights set on becoming the standard for the great comprehensive public research universities of the new century, we strive to serve the people of Colorado and to engage with the world through excellence in our teaching, research, creative work, and service.

     
  • richardmitnick 12:13 pm on April 10, 2020 Permalink | Reply
    Tags: , , , Neutrinos,   

    From Fermi National Accelerator Lab: “The cold eyes of DUNE” 

    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.

    April 9, 2020
    Jerald Pinson

    How do you detect a particle that has almost no mass, feels only two of the four fundamental forces, and can travel unhindered through solid lead for an entire light-year without ever interacting with matter? This is the problem posed by neutrinos, ghostly particles that are generated in the trillions by nuclear reactions in stars, including our sun, and on Earth. Scientists can also produce neutrinos to study in controlled experiments using particle accelerators. One of the ways neutrinos can be detected is with large vats filled with liquid argon and wrapped with a complex web of integrated circuitry that can operate in temperatures colder than the average day on Neptune.

    Industry does not typically use electronics that operate at cryogenic temperatures, so particle physicists have had to engineer their own. A collaboration of several Department of Energy national labs, including Fermilab, has been developing prototypes of the electronics that will ultimately be used in the international Deep Underground Neutrino Experiment, called DUNE, hosted by Fermilab.

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

    SURF DUNE LBNF Caverns at Sanford Lab

    DUNE will generate an intense beam of neutrinos at Fermilab in Illinois and send it 800 miles through the Earth’s crust to detectors in South Dakota. Results from the experiment may help scientists understand why there is more matter than antimatter, an imbalance that led to the formation of our universe.

    2
    Analog-to-digital convertors built to work at cryogenic temperatures, such as the prototype pictured here, will operate inside of liquid-argon chambers in the Deep Underground Neutrino Experiment. Photo: Alber Dyer, Fermilab

    Physics and chill

    DUNE’s neutrino detectors will be massive: a total of four tanks, each as high as a four-story building, will contain a combined 70,000 tons of liquid argon and be situated in a cavern a mile beneath Earth’s surface.

    FNAL DUNE Argon tank at SURF

    Argon occurs naturally as a gas in our atmosphere, and turning it into a liquid entails chilling it to extremely cold temperatures. The atomic nuclei of liquid argon are so densely packed together that some of the famously elusive neutrinos traveling from Fermilab will interact with them, leaving behind tell-tale signs of their passing. The resulting collision produces different particles that scatter in all directions, including electrons, which physicists use to reconstruct the path of the otherwise invisible neutrino.

    A strong electric field maintained within the detector causes the free electrons to drift toward wires attached to sensitive electronics. As the electrons travel past the wires, they generate small voltage pulses that are recorded by electronics in the liquid-argon chamber. Amplifiers in the chamber then boost the signal by increasing the voltage, after which they are converted to digital data. Finally, the signals collected and digitized across the entire chamber are merged together and sent to computers outside the detector for storage and analysis.

    Challenges for chilled electronics

    The electronics in neutrino detectors work the same way as the technology we use in our everyday lives, with one major exception. The integrated circuitry in our phones, computers, cameras, cars, microwaves and other devices has been developed to operate at or around room temperature, down to about minus 40 degrees Celsius. The liquid argon in neutrino detectors, however, is cooled to around minus 200 degrees.

    “If you use electronics designed to work at room temperature, rarely do you find that they work anywhere nearly as well as those designed to operate at cryogenic temperatures,” said Fermilab scientist David Christian.

    In the past, this issue was sidestepped altogether by placing the electronic circuitry outside of the argon tanks. But when you’re measuring a limited number of electrons, even the slightest amount of electronics noise can mask the signal you’re looking for.

    The easiest way to mitigate the problem involves the same tactic you use to keep food from spoiling: Keep it cold. If all the electronics are submerged in the liquid argon, there are fewer thermal vibrations from atoms and a larger signal-to-noise ratio. Placing the electronics in the liquid-argon tank has the added benefit of decreasing the amount of wire you have to use to deliver signals to the amplifiers. If, for example, amplifiers and analog-to-digital converters are kept outside the chamber (as they are in some neutrino detectors), long wires have to connect them to the detectors on the inside.

    “If you put the electronics inside the cold chamber, you have much shorter wires and therefore lower noise,” said Carl Grace, an engineer at Lawrence Berkeley National Laboratory. “You amplify the signal and digitize it in the argon chamber. You then have a digital interface to the outside world in which noise is no longer a concern.”

    There are several design challenges these teams have had to overcome during development, not the least of which was determining how to test the durability of the devices.

    “These chips will have to operate for a minimum of 20-odd years, hopefully longer,” Grace said. “And because of the nature of the argon chambers, the electronics that get put inside of them can’t cannot be changed. They cannot be swapped out or repaired in any way.”

    Since Grace and his team don’t have 20 years in which to test their prototypes, they’ve approximated the effects of aging by increasing the amount of voltage powering the chips to simulate the wear and tear of regular, long-term operation.

    “We take the electronics, cool them down and then elevate their voltage to accelerate their aging,” Grace said. “By observing their behavior over a relatively short period of time, we can we can then estimate how long the electronics would last if they were operated at the voltages for which they were designed.”

    Resistance in circuits

    Not only do these circuits need to be built to last for decades, they also need to be made more durable in another way.

    Electronic circuitry has a certain amount of resistance to the electric current flowing through it. As electrons pass through a circuit, they interact with the vibrating atoms within the conducting material, which slows them down. But these interactions are reduced when the electronics are cooled to cryogenic temperatures, and the electrons that constitute the signal move more quickly on average.

    This is a good thing in terms of output; the integrated circuits being built for DUNE will work more efficiently when placed in the liquid argon. But, as the electrons travel faster through the circuits as temperatures drop, they can begin to do damage to the circuitry itself.

    “If electrons have a high enough kinetic energy, they can actually start ripping atoms from the crystal structure of the conducting material,” Grace said. “It’s like bullets hitting a wall. The wall starts to lose integrity over time.”

    DUNE chips are designed to mitigate this effect. The chips are fabricated using large constituent devices to minimize the amount of damage accrued, and they are used at lower voltages than normally used at room temperature. Scientists can also adjust operating parameters over time to compensate for any damage that occurs during their many years of use.

    Timeline to completion

    With preparations for the DUNE well under way and the experiment slated to begin generating data by 2027, scientists from many institutions have been hard at work developing electronic prototypes.

    Scientists at Brookhaven National Laboratory are working on perfecting the amplifier, while teams from Fermilab, Brookhaven and Berkeley labs are collaborating on the analog-to-digital converter design.

    Fermilab has also teamed up with Southern Methodist University to develop the electronic component that merges all of the data within an argon tank before it’s transmitted to electronics located outside the cold detector. Finally, researchers working on a competing design at SLAC National Accelerator Laboratory are trying to find a way to efficiently combine all three components into one integrated circuit.

    The various teams plan to submit their circuit designs this summer for review. The selected designs will be built and ultimately installed in the DUNE neutrino detectors at the Sanford Underground Neutrino Facility in South Dakota.

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA

    U.S. work on LBNF/DUNE is supported by the Department of Energy Office of Science.

    See the full here.


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    Please help promote STEM in your local schools.

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    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
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