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  • richardmitnick 10:58 am on January 31, 2023 Permalink | Reply
    Tags: "Proposed experiment seeks origin of cosmic neutrinos", , Most astronomers trek to the mountaintops to study the stars but a group of physicists are seeking the secrets of the cosmos with a detector at the bottom of the ocean., Neutrinos, P-ONE experiment UBC, ,   

    From “Symmetry”: “Proposed experiment seeks origin of cosmic neutrinos” 

    Symmetry Mag

    From “Symmetry”

    1.31.23
    Mara Johnson-Groh

    3
    P-ONE experiment

    Most astronomers trek to the mountaintops to study the stars but a group of physicists are seeking the secrets of the cosmos with a detector at the bottom of the ocean.

    Deep underwater, far off the coast of British Columbia, Canada, the world is cold and dark. Rising from the sand below bob a set of submerged buoys, securely fastened with mooring lines to the ocean floor. Tethered at intervals along each line are large glass spheres housing sensitive, light-detecting instruments.

    The scientists who constructed these deep-sea instruments aren’t biologists or oceanographers. They’re physicists and astronomers. It’s here, 2 kilometers under the frigid Pacific waves, that they are hoping to capture wily, shape-shifting, nearly massless particles called neutrinos that could change our view of the universe.

    Particle decays regularly produce mid-to-low-energy neutrinos, the kind that physicists spend the bulk of their time observing. But every once and a while a different kind of neutrino is detected—a high-energy cosmic neutrino.

    Scientists know from the intense energy of these superpowered particles that they must have been accelerated by extreme objects outside our galaxy.

    “These energies are really hard to imagine,” says Juan Pablo Yanez Garza, a physicist and assistant professor at the University of Alberta. “When you consider how we accelerate particles in our labs, like the Large Hadron Collider, and plug in the typical magnetic fields in the universe, you realize that you would need an ‘accelerator’ the size of an entire galaxy to energize neutrinos this much.”

    Using gigantic, specialized detectors, scientists have just begun to pinpoint some of the extragalactic origins of these particles. Figuring out where high-energy neutrinos come from can help solve longstanding mysteries about the behemoth cosmic accelerators that produce them, resolve unanswered questions about cosmic rays, and even provide hints about the origins of dark matter.

    The instruments in the Pacific Ocean are some of the first steps toward a proposed experiment called the Pacific Ocean Neutrino Experiment, or P-ONE, which scientists hope will help them uncover cosmic neutrino origins.

    1
    P-ONE experiment. Credit: UBC.

    2
    P-ONE experiment. Credit: UBC.

    Cosmic messengers

    Due to the vastness of space and the ubiquity of view-blocking dust clouds, most of the universe is hidden from photon-based telescopes. Instead, astronomers look for messenger particles, such as neutrinos, to learn more about these dark regions, which include some of the highest-powered objects in the universe. Neutrinos are ideal cosmic messengers. Their limited interactions with other particles and chargeless state mean they can race across space unencumbered by magnetic fields and dust clouds. However, this introversion means they can be hard to capture when they reach Earth.

    Scientists have developed goliath detectors in hopes of upping the odds. Even so, the chance of catching a high-energy cosmic neutrino is slim. In its 12 years of operation, the IceCube detector—one of the premier cosmic neutrino observatories, located at the South Pole with a cubic kilometer of detection volume—has caught only a few hundred.

    “With more than 10 years of data from IceCube, we still do not know what most of the cosmic high-energy neutrino sources are,” says Lisa Schumacher, a research scientist at the Technical University of Munich, who is involved with both IceCube and P-ONE.

    But we do know about some of them. In 2018, the IceCube observatory was the first to pinpoint a source of high-energy neutrinos: a blazar 3.7 billion light years away. A blazar is the nucleus of a galaxy powered by a black hole that can accelerate particles in huge jets at nearly the speed of light.

    Then in 2022, IceCube announced a second source in another active galaxy just 47 million light years away, where scientists think neutrinos and other matter are accelerated around a giant black hole.

    While active galaxies are now a confirmed source, statistical analyses show that they alone can’t account for all high-energy astrophysical neutrinos. “The problem is we need more data,” says Elisa Resconi, a professor at the Technical University of Munich who has worked with IceCube. “Statistics is what’s limiting us right now.”

    A light in the dark

    To gather more data, scientists like Resconi have been dreaming up new neutrino observatories. Resconi spearheaded an effort to launch the new large-scale P-ONE experiment. With a goal of building hundreds of neutrino detectors along several 1-kilometer-long lines, the experiment is intended to complement IceCube. From its location in the northeast Pacific, P-ONE could grab neutrinos from different parts of the universe that IceCube can’t see.

    “The idea is to have a telescope that would be similar to IceCube, but with improvements given advances in technology over the last decade” Resconi says. “Our aim is to really complement other detectors, as we want to be able to work together and pool our data.”

    P-ONE will detect neutrinos in the same way IceCube has for years—by looking for the tiny streaks of light neutrinos create as they bump into other particles in a medium such as water or ice.

    To block out other atmospheric particles that can mimic these tiny streaks, scientists often install neutrino detectors underground. Some neutrino detectors, like the Sudbury Neutrino Observatory in Canada and Super-Kamiokande in Japan, are built in former or currently operating mines. Others, like the Baikal Deep Underwater Neutrino Telescope in Russia and the future Cubic Kilometre Neutrino Telescope off the coast of Italy and France, are built deep underwater. P-ONE scientists hope to add to—and widen the reach of—the aquatic fleet.

    P-ONE’s location in water gives it an edge over IceCube, which is enshrined 2,000 meters deep in glacial ice. Though the Antarctic ice is highly transparent, its crystalline structure prevents a beam of light from traveling along a perfectly straight line. Since the angle and direction of the streaks are used to identify where in the sky the neutrino came from, this diffusion makes it harder for IceCube to identify cosmic neutrino factories.

    “The total amount of light the detectors will measure with P-ONE will be a little bit less than IceCube, but we can better reconstruct where the light came from,” Schumacher says.

    Neutrinos, bioluminescence, and more

    Scientists have proposed to build P-ONE off the backbone of Ocean Networks Canada’s oceanographic observatory, the largest permanent oceanographic infrastructure in the world. If they do, P-ONE scientists will be able to tap into the network of hundreds of kilometers of optical cables and substations already installed on the ocean floor, saving the experiment time and money.

    In return, P-ONE could also open new doors in oceanography and biology. Extra detectors, like hydrophones or oxygen sensors, could be attached to the P-ONE lines to measure the ocean’s vitals and conduct acoustic tomography, which uses low-frequency signals to measure ocean currents and temperature over large regions. And since P-ONE’s detectors are light-sensitive, they could also be used to study long-term changes in bioluminescence activity in the deep.

    In 2018, the project scientists deployed STRAW-a, an instrument cluster designed to test the suitability of the site for the P-ONE experiment. Along with STRAW-b, which finished testing in 2021, the pathfinder mission proved the location’s clear waters would make a good canvas for neutrino detection. Now, the scientists are preparing for the next stage: installing a prototype instrument, planned for spring of 2024.

    The prototype phase will see at least three lines, each with 20 detectors, installed on the ocean floor. This should allow scientists to capture 30 or so atmospheric neutrinos—enough to calibrate and provide proof-of-concept. If all goes well, P-ONE will eventually consist of 70 1,000-meter-long lines spread over a square kilometer of ocean. And if interest in the project grows, the experiment is extremely scalable.

    “With P-ONE, IceCube and other detectors in the works, we can really do neutrino astronomy properly,” Resconi says. “We’ll be able to pinpoint many objects and do population studies, which can tell us which objects produce the most neutrinos.”

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:43 pm on January 30, 2023 Permalink | Reply
    Tags: "Probing Majorana Neutrinos", , , , Neutrinos, ,   

    From “Physics” : “Probing Majorana Neutrinos” 

    About Physics

    From “Physics”

    1.30.23
    Laura Baudis | University of Zürich

    Detecting neutrinoless double-beta decay would confirm that the neutrino is its own antiparticle. Data from the KamLAND-Zen experiment contain no strong evidence of such events, constraining neutrino properties.

    1
    Figure 1: The 136Xe isotope is known to decay via double-beta decay (left), in which two protons transform into two neutrons, emitting two electrons and two antineutrinos. If neutrinos are their own antiparticles, 136Xe can undergo neutrinoless double-beta decay (right), in which no neutrinos are emitted.

    Despite being among the most abundant particles in the Universe, neutrinos are extremely difficult to detect. Almost 100 years after they were predicted, and almost 70 years after their detection, several of the particles’ properties remain unknown, most notably their mass and their “nature”—whether they are their own antiparticles. An exceedingly rare nuclear decay without the emission of neutrinos, called neutrinoless double-beta ( 0νββ) decay, could shed light on these questions (see Viewpoint: The Hunt for No Neutrinos), but so far this hypothetical process has not been observed. Now, the KamLAND-Zen Collaboration has reported an improved search for 0νββ decay in a xenon-loaded liquid scintillator detector, with an exposure that reaches 1 tonne-year for the first time [1]. The resulting lower limit for the decay half-life translates into an upper limit on the effective neutrino mass of around 100 meV, which approaches lower-limit estimates that come from other neutrino observations. The implication is that physicists may be closing in on this neutrino mystery.

    While the Standard Model predicts that neutrinos are massless, we know from neutrino-oscillation experiments that they must be massive: specifically, for neutrinos to oscillate between their three “flavours,” the differences of their squared masses must be nonzero.

    The oscillation data imply that at least one neutrino state must have a mass larger than about 50 meV, but the observations do not tell us about the absolute mass scale, or which of the three states is the heaviest (the data allow two possible mass orderings termed “normal” and “inverted”). They also do not answer the fundamental question of why neutrinos are so much lighter than other elementary particles.

    One method to constrain neutrino masses is to study nuclei that decay by double-beta decay ( 2νββ), in which two neutrons transform into two protons, emitting two electrons and two antineutrinos. If, however, neutrinos are Majorana particles—that is, if they are their own antiparticle—then a 2νββ-decaying nucleus will sometimes decay without emitting any neutrinos—a process known as 0νββ decay (Fig. 1). Most attempts to observe this decay involve measuring the total energy of the two electrons and looking for a peak at the Q value of the reaction, which is the difference between the rest-mass energy of the initial and final products. Such a peak would imply a surplus of events in which no energy is carried away by neutrinos. Detecting this signature presents a formidable challenge, as the 0νββ decay is expected to be rare. Experiments must meet a number of requirements: a very large number of double-beta-decaying nuclei, an extremely low level of background, an excellent energy resolution to filter out a potential signal, and a high efficiency to detect the two final-state electrons. Seeking to optimize these characteristics, physicists have employed a variety of isotopes and detector concepts, including crystals cooled to cryogenic temperatures, high-pressure gas detectors, and large liquid scintillators [2].

    The KamLAND-Zen experiment at the Kamioka Observatory in Japan searches for 0νββ decay using a large liquid scintillator loaded with the 136Xe isotope, which is known to undergo double-beta decay. To ensure that the level of background events is as low as possible, the detector has an onion-like structure (Fig. 2). A spherical inner balloon holds 13 tons of liquid scintillator in which 745 kg of Xe (comprising about 91% 136Xe) are dissolved. Surrounding this inner core are three concentric shells: the first contains a liquid scintillator, the second holds 1879 large photomultiplier tubes (PMTs), and the third is a water Čerenkov detector. Particles interacting in the liquid scintillator—including particles created by rare decays of 136Xe nuclei—generate light that is detected by the PMTs. From these signals, each event’s energy and position are reconstructed with a relative energy resolution of 4.2% around the Q value (2.48 MeV) and a spatial uncertainty of 8.7 cm.

    In their recent study, the KamLAND-Zen team analyzed data collected between February 2019 and May 2021 and found a total of 24 candidate events. With no excess over the expected background, this detection count corresponds to fewer than 6.2 events (at the 90% confidence level) that can be attributed to 0νββ decays. Combined with the collaboration’s previous result [3] using half the target mass (381 kg of enriched Xe), the new result implies a lower limit on the half-life of 2.3 × 1026 years. If one assumes that the decay occurs predominantly through the exchange of light Majorana neutrinos, then the half-life limit translates into an upper limit on the effective Majorana neutrino mass in the range 36–156 meV. This minimum half-life is just within the 1026–1028-year range associated with the inverted neutrino mass ordering, meaning KamLAND-Zen starts, for the first time, to probe this scenario, and partially excludes theoretical models that predict a Majorana neutrino mass in this region.

    The experiment’s exposure of almost one tonne-year is a first in the field of 0νββ-decay searches. While its energy resolution is 10 times less precise than those of crystal-type detectors (which achieve relative resolutions at the per-mille level), the obtained sensitivity demonstrates the power of a large quantity of the decaying isotope combined with a low, albeit nonzero, background. Given the moderate depth of the Kamioka Observatory below ground, this background stems partly from long-lived spallation products—with half-lives lasting from several hours to days—generated in Xe by cosmic-ray-induced muons.

    This background can be excluded with new event-classification methods, which rely on time and distance estimators and on the detection of multiple neutrons emitted in the spallation process. Researchers are working on improving these methods by the use of faster electronics.

    The other limiting background comes from the tail of 136Xe’s 2νββ
    -decay spectrum, the effect of which can only be reduced by improving the energy resolution. Boosting the resolution by a factor of 2 is a major goal of the future KamLAND2-Zen detector, which will use a liquid scintillator with a higher light yield and high-quantum-efficiency PMTs. With its one tonne of 136Xe, KamLAND2-Zen should reach a sensitivity of 20 meV after five years of data gathering. Thus, while KamLAND-Zen has only started to probe the inverted neutrino mass ordering region, the upgrade could cover the full inverted-ordering scenario, for which the smallest allowed effective mass value is (18.4 ± 1.3) meV [4]. This goal aligns with those of other planned projects, such as CUPID [5], LEGEND-1000 [6], nEXO [7], PandaX-III [8], DARWIN [9], NEXT-HD [10], and SNO+[11]. With half-life sensitivities around 1028 years, these future experiments will have a significant chance of discovering 0νββ decays and could thus resolve some of the mysteries surrounding neutrinos. Even more importantly than pinning down the particle’s mass and Majorana nature, such a discovery would establish that a fundamental symmetry of nature—the conservation of lepton number—is violated. Such a violation is considered an important ingredient in models that try to explain our Universe’s matter–antimatter asymmetry.

    References

    1. S. Abe et al. (KamLAND-Zen Collaboration), “Search for the Majorana nature of neutrinos in the inverted mass ordering region with KamLAND-Zen,” Phys. Rev. Lett. 130, 051801 (2023).
    2. M. Agostini et al., “Toward the discovery of matter creation with neutrinoless double-beta decay,” arXiv:2202.01787 [hep-ex].
    3. A. Gando et al., “Search for Majorana neutrinos near the inverted mass hierarchy region with KamLAND-Zen,” Phys. Rev. Lett. 117, 082503 (2016).
    4. M. Agostini et al., “Testing the inverted neutrino mass ordering with neutrinoless double-β decay,” Phys. Rev. C 104, L042501 (2021).
    5. W. R. Armstrong et al. (CUPID Interest Group), “CUPID pre-CDR,” arXiv: 1907.09376.
    6. N. Abgrall et al. (LEGEND Collaboration), “LEGEND-1000 preconceptual design report,” arXiv:2107.11462.
    7. G Adhikari et al. (nEXO Collaboration), “nEXO: neutrinoless double beta decay search beyond 10^28 year half-life sensitivity,” J. Phys. G: Nucl. Part. Phys. 49, 015104 (2021).
    8. X. Chen et al., “PandaX-III: Searching for neutrinoless double beta decay with high pressure 136Xe gas time projection chambers,” Sci. China: Phys., Mech. Astron. 60, 061011 (2017).
    9. F. Agostini et al. (DARWIN Collaboration), “Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of 136Xe,” Eur. Phys. J. C 80, 808 (2020).
    10. C. Adams et al. (NEXT Collaboration), “Sensitivity of a tonne-scale NEXT detector for neutrinoless double-beta decay searches,” J. High Energ. Phys. 2021, 164 (2021).
    11. V. Albanese et al. (SNO+ Collaboration), “The SNO+ experiment,” J. Instrum. 16, P08059 (2021).

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments.

     
  • richardmitnick 12:11 pm on January 24, 2023 Permalink | Reply
    Tags: "Ways to weigh a neutrino", Another process that produces a neutrino is electron capture: A proton in an unstable nucleus captures an electron from the inner shell and converts to a neutron and ejects a neutrino., , , For decades scientists have tried to find a way to measure the mass of the lightest matter particle known to exist. Three new approaches now have a chance to succeed., In a process called beta decay a neutron in an unstable nucleus transforms into a proton to restore balance. As the neutron becomes a proton it emits a negatively charged electron—and a neutrino., , Neutrinos, Neutrinos are very very small. But they outnumber the other fundamental particles by a factor of 10 billion., , , They probably influenced the formation of structures in the early universe so knowing their mass is critical to closing gaps in our understanding of the cosmos., To measure directly or indirectly-that is the question.   

    From “Symmetry”: “Ways to weigh a neutrino” 

    Symmetry Mag

    From “Symmetry”

    1.24.23
    Elise Overgaard

    For decades scientists have tried to find a way to measure the mass of the lightest matter particle known to exist. Three new approaches now have a chance to succeed.

    In 1980, Hamish Robertson was a tenured professor at Michigan State. He’d been there since his postdoc in 1971, and he was content. “I want to stress how valued and happy I felt there,” he says. “It was, and still is, an outstanding place.”

    But he and his friend and colleague, Tom Bowles, had begun to hatch an idea that would take him far from MSU. They were devising a new experiment to measure the mass of the elusive and perplexingly light neutrino.

    Neutrinos are the only fundamental particles whose mass we still don’t know. As their name implies, neutrinos are very very small. But they outnumber the other fundamental particles by a factor of 10 billion.

    Their collective abundance makes it likely that they probably influenced the formation of structures in the early universe so knowing their mass is critical to closing gaps in our understanding of the cosmos.

    But how do you measure something with a mass so small it approaches zero? Hundreds of physicists, including Robertson, have devoted their careers to solving this problem, and they’re seeing progress. Research projects underway in Europe and the United States fuel a sense of optimism that the task can be accomplished.

    To measure directly or indirectly-that is the question

    If you were asked to weigh something—your dog for example—how would you do it?

    You could set the dog in your car, watch the compression, measure how many inches the car is displaced, then convert that into a measurement of the dog’s mass. You’d need to know the weight of the car, the technical specifications of the shocks, how much air is in the tires, and something about spring constants. That’s an indirect (and hard) way.

    Alternatively, you could simply set the dog on a bathroom scale.

    The decision on which approach to use, direct versus indirect, depends on what resources you have available. If you don’t have a bathroom scale, an indirect measurement using your car could hypothetically be your best option.

    When it comes to neutrinos, scientists have faced a similar situation.

    In 1987, astrophysicists interested in the mass of neutrinos got an assist from a rare nearby supernova. The spectral data they collected from the stellar explosion helped them make an indirect measurement that gave them an upper limit on the neutrino mass. As in the car example, they used mathematical models, known quantities, and interactions between many parts of a system to make a calculation.

    Cosmologists have also made an indirect measurement by looking for the imprint of neutrino mass on faint radiation in space called the cosmic microwave background [CMB], says Diana Parno, an associate professor at Carnegie Mellon University and US spokesperson for the Karlsruhe Tritium Neutrino direct mass experiment, or KATRIN.

    “What we would ideally like is an Earth-based measurement of the neutrino mass, and then we can compare that against the cosmological measurement,” Parno says.

    So, while cosmologists and astrophysicists look to the sky, experimentalists like Robertson, Bowles and Parno take the direct approach to searching for the neutrino mass. It’s tough—the ghostly particles don’t interact with electromagnetic fields or the nuclear strong force, and they’re so light that gravity barely pulls on them. Experimentalists have to get creative.

    Building a bathroom scale for neutrinos

    Back in 1980, Robertson and Bowles developed a new idea for making a direct neutrino mass measurement.

    But there were only a few places that had the equipment, the funding and other resources required for the experiment they wanted to propose. The DOE’s Los Alamos National Laboratory was one of them.

    Bowles already worked in Los Alamos, and he wanted Robertson to join him. Robertson was tempted. “Since I first was aware of science as a child, I knew about Los Alamos. I always thought it would be the most extraordinary place to be,” he says.

    To convince Robertson to take the dive, Bowles invited him to visit the lab. One night he treated Robertson to dinner at Southwest restaurant Rancho de Chimayo. “On the way back, we stopped the car and turned off the lights,” Robertson says. “We got out so I could marvel at the spectacular carpet of stars in the clear mountain air.”

    Robertson was sold. He was ready to embark on the journey to measure neutrino mass.

    So how does one go about building a bathroom scale for neutrinos? If you have a squirmy dog that won’t sit on the scale, you can weigh yourself alone, then weigh yourself with your pet. The difference between the two is the weight of the dog. Neutrino researchers use that same idea, taking advantage of processes that produce neutrinos.

    In a process called beta decay a neutron in an unstable nucleus transforms into a proton to restore balance. As the neutron becomes a proton it emits a negatively charged electron—and a neutrino.

    Another process that produces a neutrino is electron capture: A proton in an unstable nucleus captures an electron from the inner shell and converts to a neutron and ejects a neutrino.

    In both cases the events produce a very specific amount of energy—you can look it up in a table. That exact amount of energy is the difference between the mass of the parent atom and the mass of the daughter atom. And that energy is shared between the products: the neutrino and the electron in beta decay, or the neutrino and the excited daughter atom in electron capture.

    Experimentalists measure energies, hence they can determine the energy taken by the neutrino. Then they take advantage of that old reliable equation E = mc2 and convert the neutrino’s energy to mass.

    Awkward space in the Standard Model

    Why is investigating the mass of neutrinos so alluring to scientists like Robertson and Bowles? Because the unresolved problem has shaken scientists’ understanding of the universe.

    The Standard Model of particle physics—our current best explanation of the fundamental forces and particles that make up everything—predicts that neutrinos should have no mass.

    But oscillation experiments in the 1990s showed that they must have mass.

    “Neutrino mass is our first laboratory evidence for physics beyond the Standard Model, and that’s so cool,” Parno says.

    As Robertson explains: “Neutrinos are the only matter particles for which the Standard Model made a prediction for what its mass would be. And that prediction was wrong.

    “We have examples of things that are not in the Standard Model. Gravity is not in the Standard Model. The mass of quarks is not predicted. But there is only this one case where the Standard Model actually made a prediction, and it got it wrong.”

    The upper limit for the neutrino mass, as determined indirectly by cosmology, is roughly one millionth the mass of the next lightest particle, the electron. That’s like the gap between one mouse, which weighs roughly 25 grams, and five elephants, which together weigh roughly 25,000 kilograms. “That’s an enormous gap,” says Parno. “It’s awkward to have this empty space in the Standard Model.”

    The gap means that neutrino masses might be special. Or they might not be. But until we have a measurement to work with, we can’t really say anything definitive. So making that measurement is a crucial first step.

    Even if researchers achieved a result for the mass of the neutrino, the work would not be done. It would help rule out some theories and models, but there would still be questions, says Patrick Huber, neutrino theorist and director of the Center for Neutrino Physics at Virginia Tech.

    “It’s not like once you have the measurement, you immediately select the right model,” he says. “It’s not like every theorist has predicted a certain neutrino mass, and somebody has the right theory once it’s measured. But it would lead to a whole bunch of broader questions.”

    Huber has dedicated his career to neutrinos for this exact reason. “If they see the neutrino mass, this will be very exciting. But what would be even more exciting is if they’re not seeing the neutrino mass where they should have seen it, because that means something new is happening,” he says. “Then we are forced to really start thinking anew.”

    A ghost worth chasing

    Back to the 1980s—Bowles’s persuasion had worked. “The siren song of Los Alamos was too strong to resist,” Robertson says.

    Robertson’s wife was also interested in heading out west. As a female nuclear physicist in a male-dominated lab in the ’70s, she had faced an uphill battle to navigate her career. Together, husband and wife secured jobs at the lab and flew down to buy a house. “On the glide path into Albuquerque, I still remember the feeling of elation,” Robertson says. “It was a new beginning.”

    A few months later, they officially made the move, with their 6-month-old son in tow.

    In 1972 a Swedish physicist named Karl-Erik Bergkvist had declared a new neutrino mass limit: 55 electronvolts. Robertson, Bowles and their colleagues thought they could do better. Their idea was to study beta decay using tritium, a radioactive isotope of hydrogen. Bergkvist had also used tritium, but it was a form implanted into aluminum. Robertson and Bowles wanted to use it in a more pure, gaseous form.

    The lab administration was open to their project. “They said, ‘How much money do you need?’ Well, I had no idea,” Robertson says. So he threw out a number. “They said, ‘Okay, fine.’ So that was it. Off we went.”

    With that funding—which in the end wasn’t quite enough, but at least got them started—they pushed the limit down to about 10 electronvolts. Importantly, they had proved that tritium decay experiments could work.

    In 1988, Robertson shifted gears and joined the Sudbury Neutrino Observatory.

    In 2001 the group demonstrated neutrino oscillation—a finding that proved neutrinos have mass and that eventually earned the 2015 Nobel Prize in Physics.

    Having confirmed that neutrinos have mass, scientists returned to the quest to build a bathroom scale for neutrinos. The KATRIN experiment [above] was forming, and the collaboration members asked everyone who had worked on a tritium experiment in the past to join. Robertson had moved to the University of Washington by then, but he joined the collaboration happily, even offering to design and provide the detector system for the project.

    Nestled in Karlsruhe, Germany, the KATRIN experiment now relies on contributions from 150 researchers from seven countries.

    Parno is one of those researchers. Like others, she was drawn to the experiment by the thrill of chasing something unknown. “Neutrinos are really weird,” she says. “They keep on surprising and confusing us. I think neutrinos still have a lot to teach us.”

    KATRIN is the most advanced direct mass measurement experiment. The KATRIN collaboration published an exciting result in February 2022: Neutrinos must weigh less than 0.8 electronvolts [Nature Physics (below)].

    Fig. 1: Illustration of the 70-m-long KATRIN beamline.
    3
    The main components are labelled. The transport of β-electrons and magnetic adiabatic collimation of their momenta p are illustrated [a–f]. View into the tritium source depicts three systematic effects: molecular excitations during β-decay (a), scattering of electrons off the gas molecules (b) and spatial distribution of the electric potential in the source Usrc(r, z) (c). The view into the spectrometer illustrates the main background processes arising from radon decays inside the volume of the spectrometer (d), highly excited Rydberg atoms sputtered off from the structural material via α-decays of 210Po (e) and positive ions created in a Penning trap between the two spectrometers (f). Low-energy electrons, created in the volume as a consequence of radon decays or Rydberg-atom ionizations, can be accelerated by qUana towards the focal-plane detector, making them indistinguishable from signal electrons.

    Oscillation experiments provided a floor, and the KATRIN result provides a ceiling. “We are closing in,” Robertson says.

    This range is much tighter than the one from the indirect astrophysical supernova measurement. “The supernova limit is about 5.7 electronvolts, about seven times looser than the current KATRIN limit,” Parno says.

    And it’s close to the limit from cosmological indirect measurements, which is somewhere in the range 0.12 to 0.5 electronvolts, depending which parameters are used in the model, Robertson says.

    KATRIN’s 0.8 electronvolt number is the new benchmark for all direct mass experiments, but other inventive scientists are on KATRIN’s heels.

    New approaches

    In 2009, Joe Formaggio, a professor at the Massachusetts Institute of Technology, and Benjamin Monreal, an associate professor at Case Western Reserve University, had another tritium-based idea, which became the foundation of the neutrino mass experiment known as Project 8.

    “They proposed just a really beautiful idea,” Robertson says. “It’s one of those ideas where you say: Oh yeah, I wish I thought of that!”

    Robertson has worked with the Project 8 team since its inception. The experiment also uses tritium decay, but Project 8 determines the energy of the emitted electron differently. They measure the frequency of the electron’s cyclotron radiation—the microwave radiation that escapes from charged particles in circular orbit in a magnetic field.

    “The amount of power radiated is really very small, but you can measure it,” Robertson says.

    Various aspects of the experiment are still being developed and tested. If the new approach works as planned, the Project 8 team hopes to measure the neutrino mass with a sensitivity of approximately 0.04 electronvolts.

    The third technique currently under investigation as a way to directly measure neutrino mass uses molecules of the holmium isotope 163Ho. It’s challenging as well, says researcher Loredana Gastaldo, Junior Professor at the Kirchhoff Institute for Physics at the University of Heidelberg and spokesperson of the Electron Capture 163Ho, or ECHo, experiment.

    “If you want to learn more about neutrinos, you need to be creative, to find an original and clever method that allows you to really learn something about them,” she says. “The neutrinos don’t give anything up as a present, so you need to sweat a lot to gain a little bit more understanding.”

    The ECHo experiment relies on electron capture events in 163Ho. Scientists implant 163Ho ions in microcalorimeters, a totally different type of detector than the ones used in KATRIN and Project 8. “The idea is that if energy is deposited into the detector, there is an increase of temperature … and we can measure this extremely small increase in temperature with very precise thermometers,” Gastaldo says.

    Each project is different, but through human ingenuity (and persistence), direct mass measurement experiments are making strides.

    Let’s get together

    Robertson, who is now a professor emeritus at the Center for Experimental Nuclear Physics and Astrophysics at the University of Washington in Seattle, officially retired in 2017. But he’s still working on Project 8.

    The collaboration is younger than KATRIN and, so far, has done only proof-of-concept experiments. The next step is to create a full-blown large-scale detector.

    “Some days you get up and you learn something that is just not going to work,” Robertson says. “And you say: Oh my goodness, we’re doomed.

    “And then you work for another week or two—or a month or a year—and you talk to your friends, and somebody has an idea, and suddenly the sun comes out again, and that problem is solved, and you move on.

    “I still work at this 24/7 because I really love this experiment.”

    And he’s not alone. Parno, Gastaldo and Huber are just a few of the hundreds of other neutrino experts who have dedicated their careers to finding the mass of the neutrino. And they all rely on each other.

    “We are all learning from all the other groups,” Gastaldo says. “And this makes the collaborations really alive and with super interesting discussions in which all of us are gaining a lot of knowledge.”

    To maximize neutrino physicists’ ability to learn from each other, Gastaldo organized a conference, called “NuMass”, in 2016. The inaugural meeting was a gathering of 40 scientists from the US and Europe, all with different expertise. “The discussions were so deep it was unbelievable,” Gastaldo says.

    The group repeated the conference in 2018, 2020 and 2022.

    “I think it’s fantastically interesting to have so many different fields of knowledge that turn out to be necessary in order to unlock the secrets of this incredibly lightweight, incredibly rarely interacting particle that somehow shaped the universe,” Parno says.

    The optimism of neutrino mass researchers is infectious. They continue, with tangible passion, to push the limits of human ingenuity.

    And there’s always room for newcomers.

    “You have to have young people because they’re the people who actually can get stuff done,” Robertson says. “There’s this huge group of people. I’m just wandering along jumping from the shoulder of one giant to another. That’s part of what makes science fun.”

    The latest: The DOE’s Fermi National Accelerator Laboratory LBNF/DUNE experiment.



    Nature Physics
    See the science paper for instructive material with images.

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:07 pm on January 5, 2023 Permalink | Reply
    Tags: "Unraveling the neutrino’s mysteries at the Deep Underground Neutrino Experiment", , At Sudbury scientists found the reason for the missing neutrinos: Neutrinos change type-or “flavour” as they fly through space., At the Virginia Tech Center for Neutrino Physics Camillo Mariani and Patrick Huber have woven theoretical and experimental physics together in contributing to the DUNE project., , , , , John Bahcall calculated the amount of solar neutrinos he predicted the experiment would collect from the nuclear reactions that took place inside its large underground tank filled with cleaning fluid., , Neutrinos, , , Raymond Davis Jr. and John Bahcall in the 1960s attempted to count solar neutrinos at an experiment at the Homestake Mine in South Dakota the current Dune far detector site., Sanford Underground Research Laboratory, , The Homestake Experiment which ran from 1970-92 only collected one-third of the neutrinos Bahcall had predicted., , This phenomenon of changing flavours-known as “neutrino oscillation”-directly contradicts the Standard Model which had predicted neutrinos to be massless.   

    From The Virginia Polytechnic Institute and State University: “Unraveling the neutrino’s mysteries at the Deep Underground Neutrino Experiment” 

    From The Virginia Polytechnic Institute and State University

    1.4.23
    Suzanne Irby

    At the Virginia Tech Center for Neutrino Physics Camillo Mariani and Patrick Huber have woven theoretical and experimental physics together in contributing to the DUNE project.

    1
    A look inside the ProtoDune Cyrostat Final structure inside a mine in South Dakota. Photo courtesy of The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organización Europea para la Investigación Nuclear][Organization européenne pour la recherche nucléaire] [Europäische Organization für Kernforschung](CH) [CERN].

    Neutrinos mind their own business. Each second, billions of these fundamental particles will pass through stars, planets, buildings, and human bodies and will rarely ever be stopped by them, like a subatomic subway crowd. It’s why they’re often described as “ghostly” or “elusive.”

    If scientists could create and capture the rare instances when these tiny and weakly interactive particles run into something, they could step into the gray area that all physicists ultimately hope to explore, said theoretical physicist Patrick Huber: that of facts that exist outside the Standard Model of Particle Physics, beyond its explanation.

    Neutrinos live there, and so does dark matter.

    Neutrino behavior, if accurately measured, could hold the evidence for how we — and our bodies and buildings and planets and stars, all made of matter — have been able to exist since the Big Bang. “There are certain things that the Standard Model does not explain, like why there’s more matter than antimatter in the universe,” said Huber, a professor in the Department of Physics and a Roger Moore and Mojdeh Khatam-Moore Faculty Fellow in the Virginia Tech College of Science. “But we never have found the ingredients which make these known facts outside of the Standard Model really work. If there is to be a large contribution of new physics, it can only really manifest itself in neutrinos.”

    To find out what neutrinos are up to, physicists will need to shoot them from the most powerful beam ever made at a distant, massive, subterranean, and painstakingly precise particle detector. More than a thousand scientists have come together to create that kind of experiment in a decades-long project called the Deep Underground Neutrino Experiment (DUNE), hosted by the DOE’s Fermi National Accelerator Laboratory.

    __________________________________________________
    Fermilab LBNF/DUNE Neutrino Experiment


    __________________________________________________

    1
    Camillo Mariani (at left) and Patrick Huber. Photo by Steven Mackay for Virginia Tech.

    For the past decade and in the buildup to DUNE’s development, Huber has collaborated with experimental physicist Camillo Mariani at Virginia Tech’s Center for Neutrino Physics, where they’ve looked at ways to achieve the unprecedented precision an experiment like DUNE will need to measure neutrino behavior and discover the “new physics” sought by the field.

    Mariani has brought what they’ve learned to his work on DUNE’s international team as they develop the facility. Their pursuit of precision is one piece of a puzzle that Raymond Davis Jr. and John Bahcall started in the 1960s, with attempts to count solar neutrinos.

    When two physicists stared up at the sun

    Raymond Davis Jr. led one of the first experiments to measure neutrinos coming from one of nature’s abundant sources: the sun. As Davis built the experiment at the Homestake Mine in Lead, South Dakota, Bahcall calculated the amount of solar neutrinos he predicted the experiment would collect from the nuclear reactions that took place inside its large, underground tank filled with cleaning fluid. But the Homestake Experiment which ran from 1970-92 only collected one-third of the neutrinos Bahcall had predicted.

    Most physicists at the time figured that either Davis had done something wrong with the experiment or that Bahcall’s calculations were off. The issue of the missing neutrinos became known as the “solar neutrino problem” that physicists would try to solve for years. Scientists at the Sudbury Neutrino Observatory finally solved it in a 2002 experiment at a Canadian mine.

    Using a giant sphere full of heavy water, they measured neutrinos via the light produced inside by nuclear reactions. They found the reason for the missing neutrinos: Neutrinos change type-or “flavour” as they fly through space.

    There are three known neutrino flavours: electron, muon, and tau. The Sudbury experiment was sensitive to all three, unlike Davis’s, which only picked up electron neutrinos. It’s this phenomenon of changing flavours-known as “neutrino oscillation”-that directly contradicts the Standard Model which had predicted neutrinos to be massless.

    Camillo Mariani breaks down neutrino oscillations using ice cream flavors. “You can imagine that you go to an ice cream shop, and you get your favorite: banana,” Mariani said. “And then you step out, and your ice cream flavor now becomes strawberry. You take another two steps, and the strawberry becomes vanilla. Another three steps, and the vanilla becomes coconut. This is what people call an oscillation. And it can be a function of distance traveled over a function of time. And these only happen if the mass of the particle is not zero.”

    With the problem of missing solar neutrinos solved, physicists have since moved on to probing how neutrino oscillations work. The big, underlying science question today is whether these flavour changes in neutrinos and antineutrinos happen at the same rate or not, Huber said. If they oscillate differently, that difference — a physical process known as CP violation — could help to explain why our universe consists of us and our surroundings, over light and light alone.

    Physicists believe that 14 billion years ago, there were exactly the same amounts of matter and antimatter in the universe. “If that were true, and it always remained like that, then eventually, all matter and antimatter would have met and annihilated each other and become light (energy),” Huber said. “The universe would then contain only light (energy) and nothing else. Obviously, that’s not how it happened.”

    Because we exist, it’s clear that matter dominated over antimatter during the Big Bang, in a break of symmetry. Neutrino oscillations could show how this was possible by demonstrating their own asymmetry. DUNE provides a way to catch that asymmetry in the act — or not.

    The difference in oscillation rate between neutrinos and antineutrinos — or lack thereof — is not going to be glaring, Huber said, which is why physicists like him and Mariani are so fixated on precision. It could come down to tenths or hundredths of a number in DUNE’s measurements. Though it’s a feat, DUNE is the minimum needed to get it done, Huber said, because in the case of precisely measuring neutrino oscillations, “you need a Saturn rocket to fly to the moon.”

    “Physics in the last two decades has gone from a field where we’re happy just saying, ‘Oh, we’ve seen neutrinos, hooray,’ to the point where we’re trying to do very precise measurements,” Huber said. “DUNE is the epitome of that. That really is the end of a decades-long evolution where neutrino physics became more and more precise. DUNE is trying to do one of the most precise measurements ever attempted with neutrinos.”

    A Saturn rocket to fly to the moon

    There are some musts in measuring neutrino oscillations: creating enough neutrino events, only a handful of which will be snatched up by an experiment; putting enough distance between the neutrinos’ source and their endpoint for them to exhibit their oscillations; and establishing a setup that’s massive and highly-resolved enough to capture the energy the events leave behind.

    DUNE’s answer to this starts with a powerful neutrino beam based at Fermilab in Batavia, Illinois. Here, physicists will shoot neutrinos underground across 1,300 kilometers of underground distance at a 40,000-ton particle detector filled with liquid argon. The detector will be located at the same mining area used by the [Davis-Bahcall] Homestake Experiment in South Dakota.

    As neutrinos bump into the argon inside the detector and leave behind trails of energy, that material will offer unmatched precision in measuring them, Mariani said. “Essentially, it’s like taking a photo camera from the 1980s and comparing that with your phone camera that has millions of pixels,” he said.

    The College of Science has another DUNE connection, quite close, too. Kevin Pitts, who started his tenure as dean of the college this past June and who is an affiliated faculty member of the Department of Physics, last year was named the chief research officer at Fermilab. There, he oversaw the lab’s science program, which includes the multibillion-dollar DUNE project.

    “The DUNE experiment will be a truly remarkable technological achievement that will lead to truly remarkable scientific insights,” Pitts said. “This experiment will feature 40,000 tons of liquid argon a mile underground in an abandoned gold mine in the Black Hills. Scientists from around the world are contributing to this effort because they are excited by the transformational science that will be performed at this facility.”

    For years, Mariani and Huber have worked at ensuring that this part of the DUNE project doesn’t fail. Because scientists don’t actually see neutrinos themselves as the particles hit a detector, they must reconstruct the interaction that took place with the energy left behind.

    Getting that right depends on the microphysics of what happens within the interaction, Huber said. Reconstructing the interaction is as complex as tracing the effects of shooting a bullet at a clock, he said: “Depending on how you may hit the clock, you may have gears flying out, you may have the numerals fly off. To really reconstruct the clock, or the whole interaction, from that, I need to know the probability for the bullet to eject each given subpart of the system.”

    When shooting neutrinos at argon atoms, argon nuclei can eject all sorts of particles: neutrons, protons, and new particles like pions, which are easy for detectors to miss and which all need to be counted for an accurate measurement of the total energy produced by the neutrino event. “In our work with Dr. Mariani, I think we were the first group who really tried to look into the details of that and quantify what kind of systematic uncertainties would arise from that,” Huber said. “I think that work had a huge impact on how people think about designing the whole experiment.”

    Huber and Mariani see the Center for Neutrino Physics as one of the few places where that degree of collaboration between theorists and experimentalists could happen. Since its founding in 2010, the center has built up both its theoretical and experimental programs with the sense that as neutrino physics evolved, theorists and experimentalists would always need each other.

    When an experimentalist and a theorist go for coffee

    In physics, theory and experiments tend to go back and forth in a feedback cycle: the theorists put forward a question, the experimentalists figure out a way to build an experiment to try to answer the question, and once they have the data, the theorists try to figure out what it means.

    When theorists and experimentalists have trouble understanding each other, this back and forth won’t go smoothly. It’s becoming easier and easier for that to happen, Huber said, as carving out a career path in physics tends to push scientists to self-identify as either a theorist or an experimentalist. “By the time you’re a grown researcher, you often lose this ability to effectively communicate with each other,” Huber said. “I think the only way around this is regular social interaction, where in the end, you learn to understand the language of the other side.”

    Huber, the center’s director, said it’s important to look for ways to keep theorists and experimentalists talking, in theory-experiment joint seminars or in something as simple as a shared cup of coffee. “Dr. Mariani happens to have a nice coffee machine,” he said. “It’s really that you have this casual social interaction and a relationship where nobody feels embarrassed to ask stupid questions. I can go down the hallway and ask any of my experimental colleagues, ‘Hey, what happens if you did X?’ And mostly they will tell me, ‘Well, X will blow up,’ or something like that. But sometimes you find you have some genuinely interesting new things you can do.”

    So it will go with DUNE. The project’s ability to surface new insights on neutrinos will depend in part on how its scientists can center their different talents on the same question, Huber said.

    DUNE is planned to collect data on neutrino oscillations for 20 years, starting in 2029. It’ll be another 10 to 15 years before physicists can find meaning in the results. They may or may not find evidence answering the question of matter’s dominance over antimatter in the universe. But DUNE’s potential goes beyond that, Huber said.

    DUNE represents a facility with technologies physicists will be able to use in ways they haven’t yet dreamed up. “This is where it gets really interesting,” Huber said. “Once you have this new facility and technical capability, people become very creative and find thousands of other ways to extract new science from that. In reality, what we do in science is driven by curiosity. That’s the reason we’re doing this.”

    See the full article here.

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Virginia Polytechnic Institute and State University is a public, land-grant, research university with its main campus in Blacksburg, Virginia. It also has educational facilities in six regions statewide and a study-abroad site in Riva San Vitale, Switzerland. Through its Corps of Cadets ROTC program, Virginia Tech is also designated as one of six senior military colleges in the United States.

    Virginia Tech offers 280 undergraduate and graduate degree programs to some 34,400 students and manages a research portfolio of $522 million, placing it 46th among universities in the U.S. for research expenditures and the only Virginia school listed among the top 50. Virginia Tech is the state’s second-largest public university by enrollment. The deadliest mass shooting on an American college campus occurred on campus in 2007, during which a student fatally shot 32 other students and faculty members and wounded 23 other people.

     
  • richardmitnick 10:59 pm on December 19, 2022 Permalink | Reply
    Tags: "A New Day Awaits Solar Neutrinos", , Deep Underground Neutrino Experiment (DUNE) at Fermilab and SURF, In South Dakota’s Homestake gold mine [now SURF-Sanford Underground Research Facility] physicist Raymond Davis and his colleagues observed the first neutrino signal from the Sun., Jiangmen Underground Neutrino Observatory (JUNO)-a large neutrino detector in China, Neutrino oscillations—a phenomenon that is difficult to reconcile with established theories., , Neutrinos, , , Scientists say a new generation of solar-neutrino experiments may help in solving outstanding questions about both neutrinos and solar physics., , The number of neutrinos was one third of what models predicted—a mystery that led to many new experiments staking claims to different energy and length scales related to the neutrino behavior., The study of solar neutrinos began in the late 1960s.   

    From “Physics” : “A New Day Awaits Solar Neutrinos” 

    About Physics

    From “Physics”

    12.13.22

    Solar neutrinos are no longer the “stars” of neutrino research, but next-generation experiments characterizing these neutrinos may deepen our understanding of solar and neutrino physics.

    1
    Neutrino experiments, such as the Borexino detector depicted on the right, have illuminated many details about the Sun and the neutrinos it produces. Credit: Borexino Collaboration.

    Measurements of solar neutrinos proved that our star is powered by nuclear reactions while also bringing to light many other details about the Sun’s inner workings. They also led to the discovery of neutrino oscillations—a phenomenon that is difficult to reconcile with established theories.

    [Three flavours: tau and Muon and electron]

    Current neutrino research mostly relies on neutrinos generated on Earth by reactors and accelerators. But some physicists argue that there is still a lot to be done with neutrinos generated in the Sun. A new generation of solar-neutrino experiments may help in solving outstanding questions about both neutrinos and solar physics, these scientists say.

    The study of solar neutrinos began in the late 1960s. Using a detector filled with dry-cleaning fluid and placed in South Dakota’s Homestake gold mine physicist Raymond Davis and his colleagues observed the first neutrino signal from the Sun. They were surprised, however, to find that the number of neutrinos was one third of what models predicted—a mystery that led to a “neutrino gold rush,” with many new experiments staking claims to different energy and length scales related to the neutrino behavior. Eventually, physicists explained the missing neutrinos as resulting from oscillations between neutrino flavors (see Nobel Focus: Neutrino and X-ray Vision). These oscillations implied that neutrinos have mass, in tension with the standard model of particle physics.

    The study of neutrino oscillations continues with efforts to pin down the neutrino masses and mixing parameters that determine the oscillating behavior. The main target, however, is no longer solar neutrinos. “The majority of the community, by a large margin, is focused on accelerator neutrinos,” says Michael Smy from the University of California- Irvine. The reason for this shift, he says, is that an accelerator experiment can explore higher-energy neutrinos and control the source-detector distance over which oscillations may occur. Researchers can also switch the accelerator on and off, which helps remove certain backgrounds.

    On the flip side, there are advantages to using solar neutrinos. For one, the interactions between neutrinos and detector materials are generally better understood at the low energies that characterize solar neutrinos, Smy says. Solar neutrinos also come to us for “free,” so the experiments can be less expensive, says Wick Haxton from University of California, Berkeley.

    Many experiments have focused on solar neutrinos. The Borexino experiment in Italy, for example, was built with the main purpose of collecting low energy (sub-MeV) neutrinos from the Sun.

    Since the project’s start in 2007, the team has taken several steps to remove large radioactive backgrounds. “Over the years, they’ve actually mapped the whole spectrum of solar neutrinos,” Haxton says. “They were unique in that regard.” This week, the Borexino Collaboration reported observations of the neutrinos from the carbon-nitrogen-oxygen (CNO) cycle (see Viewpoint: Elemental Accounting of the Solar Interior).

    Borexino shut down in October 2021, leaving a gap in the detection capability of solar-neutrino studies. “We do not have more data to be analyzed, and therefore the CNO result is the last major output from our experiment,” says Borexino spokesperson Gioacchino Ranucci. The observations of the solar-neutrino spectrum have agreed well with solar-model predictions, and the data have placed important constraints on oscillation parameters. “But there are still questions to be solved” regarding both the Sun’s chemical makeup and “tensions” in the neutrino oscillation picture, says Ranucci.

    Haxton sees a missed opportunity in the closing of Borexino without a clear replacement. “There’s some fascinating questions about the Sun that we haven’t answered very well,” he says. Borexino demonstrated, for example, that solar-neutrino observations could help resolve uncertainties about the elemental abundances in the interior of the Sun. But more precise measurements will be needed to determine the initial ingredients out of which the Sun formed, Haxton says. He also would like to see a better accounting of the total energy in solar neutrinos, which might reveal exotic physics going on inside the Sun. Current neutrino detectors cannot provide these measurements, as they are only sensitive to the high-energy end of the solar-neutrino spectrum.

    Still, there are several solar-neutrino problems that current and planned detectors can tackle. Smy works on Japan’s Super-Kamiokande (Super-K) experiment, which has been instrumental in understanding neutrinos since it began taking data in 1996.

    It continues to be a workhorse in neutrino physics, observing neutrinos from the Sun and other sources. Smy says that Super-K’s current solar-neutrino research focuses on the matter effect—a neutrino flavor conversion that occurs in highly dense regions, such as the interior of the Sun and of Earth. The matter effect has already been observed, but Smy and his colleagues continue to analyze Super-K data in the energy region where the matter effect turns on, as this transition may contain signs of nonstandard interactions between neutrinos and other particles.

    Another focus of ongoing solar-neutrino research is pinpointing the values for the neutrino oscillation parameters. “There are interesting discrepancies in the data that we very much want to resolve,” says Shirley Li from The DOE’s Fermi National Accelerator Laboratory.. She is especially interested in an apparent disagreement between solar-neutrino observations and reactor-neutrino observations. She has looked at whether this problem could be resolved by the Deep Underground Neutrino Experiment (DUNE)—a planned neutrino detector in the Sanford Underground Research Facility (located in the former Homestake Mine where Davis performed his neutrino experiment).

    DUNE’s main goal is to observe high-energy neutrinos coming from the Fermilab accelerator. But the detector should also be able to detect solar neutrinos at the high-energy end of the solar spectrum, according to an analysis by Li and her colleagues.

    In addition to DUNE, other planned neutrino projects could provide new solar-neutrino results. Smy mentions Jiangmen Underground Neutrino Observatory (JUNO)-a large neutrino detector in China that is expected to start taking data next year.

    JUNO has the capability to detect both neutrinos from the Sun and antineutrinos from nuclear reactors. As such, it could test so-called CPT symmetry that assumes a mirror-like relation between matter and antimatter. Further down the road, researchers are proposing to install a neutrino experiment in the China Jinping Underground Laboratory, the deepest scientific facility in the world. “They have the capability of building a Borexino-like detector that’s an order of magnitude larger,” Haxton says. He thinks such an experiment could potentially fill in some of the missing pieces to our understanding of the Sun.

    The current lull in solar-neutrino physics may be a product of the earlier excitement surrounding the missing neutrino problem. “Folks were so anxious to solve the general problem that—once it was solved—they moved on to something else,” Haxton says. But he is optimistic that solar-neutrino physics will have its day again. “Physics goes in cycles.”

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments.

     
  • richardmitnick 10:35 am on December 6, 2022 Permalink | Reply
    Tags: "First DUNE science components arrive at SURF", , , , Neutrinos, , The DOE's Fermilab National Acccelerator Laboratory,   

    From The Sanford Underground Research Facility-SURF And The DOE’s Fermi National Accelerator Laboratory: “First DUNE science components arrive at SURF” 

    From The Sanford Underground Research Facility-SURF

    And

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    The DOE’s Fermi National Accelerator Laboratory-an enduring source of strength for the US contribution to scientific research worldwide.

    12.5.22
    Erin Lorraine Woodward

    1
    Due to their size, the APAs will not fit on the elevator-like conveyance used to transport people and materials through the shaft. Instead, the APAs were suspended beneath the cage to lower them underground. Photo by Matthew Kapust.

    Traveling by rail, sea, interstates, and shafts, the first components of the international Deep Underground Neutrino Experiment (DUNE) [below] have arrived at the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The anode plane assemblies, or APAs, will one day capture data left in the wake of neutrino collisions in DUNE’s Far Detector.

    “This APA arrival and test lift marks the start of DUNE onsite activities at SURF,” said Mike Headley, executive director of SURF. “I’d like to congratulate the CERN, Fermilab, University of Manchester and SURF joint team for making this first experiment lift a major success.”

    DUNE will paint a clearer picture of the origin of matter and how the universe came to be by studying neutrinos, strange subatomic particles that rarely interact with matter.

    A beam of neutrinos will travel 800 miles through the earth, from the U.S. Department of Energy’s Fermi National Accelerator Laboratory (Fermilab) near Chicago to DUNE’s massive underground detectors at SURF [below].

    More than 1,400 scientists and engineers in over 30 countries contribute to the experiment, which is hosted by Fermilab.

    “This was a test of the entire logistics chain—from the UK, to Switzerland, to Illinois, and finally to South Dakota,” said Joe Pygott, deputy head of the Fermilab South Dakota Services Division. “After a year of planning, it was satisfying to see the global effort come together.”

    Making things awkward

    Standing a staggering 19.7 feet tall and 7.5 feet wide (6.0 meters tall; 2.3 meters wide), the APAs are the largest and one of the most fragile components of DUNE. Researchers outfit the APAs’ large steel frames with hundreds of electronic read-out boards. Then, 15-miles of hair-thin copper-beryllium wire is wrapped around the frame, creating a fine, mesh-like appearance.

    3
    Standing a staggering 19.7 feet tall and 7.5 feet wide, the APAs are the largest and one of the most fragile components of DUNE. Photo courtesy CERN.

    In total, 150 APAs will be built for DUNE: 136 from the UK and 14 from the US.

    “Because of their size, fragility and cost, the APAs are classified as a ‘critical transport,’” said Olga Beltramello, a mechanical engineer at CERN.

    To tackle the logistics and transport of unusual components like the APAs, the project formed the appropriately named Awkward Material Transport Team (AMTT).

    Beltramello, a member of the AMTT, led the creation of the frames that would cradle the APAs during transport. Throughout the design phase, she anticipated the dynamics of the journey ahead—the jostle of the rail car, the lurch of ocean waves, the sway of an overhead crane.

    “We run analysis to understand how the APA would withstand the dynamics of the transport,” Beltramello said. “The calculations are complex, as vibrations from track transport in Europe are different from the tire transport in the US, which are different from sea transport.”

    With mass production of APAs underway, the team used the delivery of two prototype APAs to SURF to stress-test their transportation plan. Accelerometers and vibration detectors monitored every wobble along the way, telling researchers just how much stress the components actually experienced during the journey.

    By land and sea

    The APAs were constructed at the UK’s Daresbury Laboratory, then shipped to CERN, the European laboratory for particle physics. There, the APAs were installed and tested in ProtoDUNE.

    A massive detector in its own right, ProtoDUNE is a prototype of the DUNE detectors to be built at SURF. Researchers wanted to ensure that the APAs could withstand the extreme cold of liquid argon (minus 200 degrees Celsius) and to see if they would yield clear data signals, unobscured by background noise.

    “In ProtoDUNE, we saw lovely, clean images,” said Justin Evans, professor of physics at the University of Manchester and academic lead of the UK project for APA production.

    The APAs then journeyed by rail to the seaside; by cargo ship across the Atlantic; and 1,600-miles by semitruck across the US. The final leg of the journey was down the mile-deep Ross Shaft, to the level where crews are excavating the large caverns that will house the DUNE Far Detector. Due to their size, the APAs will not fit on the elevator-like conveyance used to transport people and materials through the shaft. Instead, the APAs were suspended beneath the cage to lower them underground.

    Jeff Barthel, SURF’s rigging supervisor who led the maneuver, said the test lift of the nearly 6,400-pound load “couldn’t have gone smoother.”

    4
    Due to their size, the APAs will not fit on the elevator-like conveyance used to transport people and materials through the shaft. Instead, the APAs were suspended beneath the cage to lower them underground. Photo by Matthew Kapust, SURF.

    Assured by the APA performance in ProtoDUNE and the successful test transport, researchers have started mass producing APAs for DUNE.

    “For me, even more important than reaching this technical goal, is the excellent collaboration between groups,” Beltramello said. “This was our first collaboration across these groups, and it was extremely successful. It’s good for the future.”

    A neutrino trap

    When excavation is complete, the caverns will provide space for detector modules filled with a combined 70,000 tons of liquid argon. The APAs will be submerged side-by-side in the frigid liquid argon, forming a series of net-like walls across the width of the detector.

    When neutrinos collide with an argon nucleus, the collisions create a cascade of charged particles. These particles, in turn, knock loose electrons from the shells of argon atoms. An electric field will push the free-floating electrons toward a wall of APAs. Like a spider’s web, the APA wires will ensnare the drifting electrons, sending shivers of data up the wires to the electrical read-out boards. Researchers see this data in the form of particle tracks.

    “The electrons are hitting these miles and miles of wires, and we get information from that little pulse of electrical current on the wire,” Evans explained. “The pattern of particles that went through the detector is mirrored in the pattern of electrons colliding with the APAs.”

    6
    ProtoDUNE particle tracks. Image courtesy DUNE collaboration.

    From these particle tracks, researchers derive information about neutrinos and their antimatter counterparts. The results will shed light on the role neutrinos played in the evolution of the universe.

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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

    Stem Education Coalition

    The DOE’s Fermi National Accelerator Laboratory, located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    __________________________________________________________
    [Earlier than the LHC at CERN, The DOE’s Fermi National Accelerator Laboratory had sought the Higgs with the Tevatron Accelerator.

    But the Tevatron could barely muster 2 TeV [Terraelectron volts], not enough energy to find the Higgs. CERN’s LHC is capable of 13 TeV.

    Another possible attempt in the U.S. would have been the Super Conducting Supercollider.

    Fermilab has gone on to become a world powerhouse in neutrino research with the LBNF/DUNE project which will send neutrinos 800 miles to SURF-The Sanford Underground Research Facility in in Lead, South Dakota.
    __________________________________________________



    __________________________________________________

    In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest. Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment). The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector. In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.
    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.
    Asteroid 11998 Fermilab is named in honor of the laboratory.
    Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.
    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.
    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.

    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.

    FNAL Icon

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

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

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

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

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

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

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The University of Washington MAJORANA Neutrinoless Double-beta Decay Experiment 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.

    The LUX Xenon dark matter detector | Sanford Underground Research Facility 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 National Accelerator Laboratory 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.

    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 Germanium Detector Array (or GERDA) experiment is searching for neutrinoless double beta decay (0νββ) in Ge-76 at the underground Laboratori Nazionali del Gran Sasso (LNGS) for a future tonne-scale 76Ge 0νββ search.

    Compact Accelerator System for Performing Astrophysical Research (CASPAR). Credit: Nick Hubbard.

    [caption id="attachment_58675" align="alignnone" width="632"] Compact Accelerator System for Performing Astrophysical Research (CASPAR). Credit: Nick Hubbard.

    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.”

    [caption id="attachment_207839" align="alignnone" width="632"] SURF- the 3D DAS experiment is studying digital acoustic sensing techniques with a novel, three-dimensional seismic array. The University of Wisconsin-Madison. The Air Force Research Laboratory. Photo by Adam Gomez. The 3D DAS is led by Stanford University and includes industry partners and seven universities.

     
  • richardmitnick 10:51 pm on December 1, 2022 Permalink | Reply
    Tags: "Neutrino detector on the move", At 4:40 p.m. today the neutrino detection system was placed inside the SBND detector hall after a successful move., , , Neutrinos, ,   

    From The DOE’s Fermi National Accelerator Laboratory: “Neutrino detector on the move” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From The DOE’s Fermi National Accelerator Laboratory-an enduring source of strength for the US contribution to scientific research worldwide.

    12.1.22
    Emily Ayshford

     At 4:40 p.m. today the neutrino detection system was placed inside the SBND detector hall after a successful move.

    After years of construction, testing and planning, an exciting move is currently underway at the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

    1
    Installation of a wire plane in the neutrino detection system for the Short-Baseline Near Detector. Photo: Ryan Postel, Fermilab.

    A neutrino detection system built for the Short-Baseline Near Detector traveled 3 miles today, Dec. 1, from the warehouse-like building in which it was constructed to its final home in the SBND detector hall.

    2
    The neutrino detection system built for the Short-Baseline Near Detector traveled 3 miles across the Fermilab site in Batavia, Illinois. Photo of detector in the transportation frame. Photo: Monica Nunes, Fermilab.

    There scientists will use a beam of particles called neutrinos to examine the collisions of these particles with atoms.

    Their goal is to learn more about the mysterious properties of neutrinos.

    Moving the system was no easy feat. As a nearly 20-foot cube, it’s the size of a small house. It weighs 20,000 pounds and contains delicate sensors and wiring that, if rattled too much, could compromise the integrity of the system.

    Scientists, engineers and Fermilab personnel have anticipated this move for years and spent countless hours preparing for it. Today was the day. The move began at 6 a.m., projected to take 8 to 10 hours. Staff began by rolling the detector system through a large roll-up door with just inches of clearance to spare. Next, they loaded it onto a flat-bed trailer using a crane. The public can get updates on the move through the lab’s social media platforms.

    Once in place on the trailer, the truck moved at a maximum speed of about 2.5 miles per hour on its 3-mile route through the Fermilab campus to the detector hall, where the crane lifted it from the trailer and back onto solid ground. Finally, crews rolled the detection system through a garage door into its new home.

    In the coming months, the system will be placed inside a large cryostat, a vessel to cool the system to low temperature that will be filled with liquid argon and complete the Short-Baseline Near Detector. In fall 2023, scientists expect to begin receiving data that will shed light on the strange behavior of the ghostly neutrinos.

    A large group of people — including scientists, engineers, riggers and safety personnel — have meticulously planned the move for years — even from the very conception of the detector. Now they are excited that the process is finally coming to fruition.

    “It’s like taking your baby to the first day of school,” said Fermilab’s Shishir Shetty, a mechanical engineer who helped design the transport system. “So many people have put their time and effort into building the detector and planning for the move, and now we are finally at the point where we get to see the results of those efforts.”

    Measurements that have never been done before

    SBND will play a key role in understanding neutrinos: subatomic particles that have very little interaction with matter but that could hold the answers to many mysteries surrounding our universe. So far, scientists have discovered three types of neutrinos. SBND, as part of Fermilab’s Short-Baseline Neutrino Program, will help confirm or refute the existence of a potential fourth kind, called a sterile neutrino.

    The Short-Baseline Neutrino Program analyzes a neutrino beam with three liquid-argon time projection chamber detectors, including the new SBND. (It is the same technology that scientists will use for the much larger detectors of the Deep Underground Neutrino Experiment.) The three detectors measure the neutrinos as they travel along a straight path, searching for signs of oscillations — the way neutrinos transform into various types as they travel. At 110 meters from the beam source, SBND is the closest detector and will help scientists better understand the original composition of the neutrino beam. (The other detectors are MicroBooNE at 470 meters away and ICARUS at 600 meters away.)

    Scientists can predict how many neutrinos and which types of neutrino they should expect to see if they know the original beam composition with high precision. A discrepancy could provide evidence for the existence of sterile neutrinos, or it could lay the groundwork for the discovery of new particles in beyond-the-standard model physics.

    “This will give us a dataset that will be 20 to 30 times larger than the current neutrino-argon interaction data set, which will allow us to do measurements that have never been done before,” said Ornella Palamara, a neutrino scientist at Fermilab and co-spokesperson for the international SBND collaboration.

    Building the detector within a transport frame

    SBND was first proposed in 2014. Construction of the detection system, which involved scientists from around the world, began in the following years. Parts began to arrive at Fermilab in 2018.

    From the beginning, scientists and engineers knew the detection system couldn’t be built in the detector hall. They needed a large assembly building to construct the system — which consists of anode and cathode wire planes, as well as light detection systems — before it would be placed in the experiment’s large cryostat, located inside Fermilab’s Booster Neutrino Beam. The cryostat will be filled with liquid argon.

    So the team began to assemble the system in the DØ Assembly Building at Fermilab and designed and built a transport frame that would house the system from the start. To build the steel frame, the engineering team had to ensure it both supported the heavy detector system, which hangs from the top beams of the frame, while also ensuring it could be easily moved when the time came. The frame includes outriggers for support, a towbar for pulling, transport stops to prevent the detector from swinging, and a hinged door to remove the system once it arrives in the detector hall.

    To help with transport, the detector system itself sits on moving devices called Hilman rollers. In the days before the move, Fermilab staff laid down steel plate tracks for the rollers to ensure minimal friction. To move it out of the building, the frame was pulled out with a fork truck onto the plates, up a ramp, and out of the building, while another fork truck acted as a brake behind the frame. A specially designed guiding system along the ramp ensured that the rollers didn’t deviate from their tracks.

    The frame with the detection system — completely wrapped in black plastic to protect the light-sensitive detector components — moved through the building’s garage door with only inches of clearance. Once outside the building and lifted onto a flatbed trailer, the frame was driven to its new home.

    Finding the right route

    This past summer, scientists and engineers conducted three trial runs to find the best transport route. They loaded up the trailer with 66,900 pounds of concrete blocks, corresponding to the weight of the detector and transportation frame. They then used accelerometers and inclinometers, including iPads, to monitor the route’s bumps, as well as the trailer’s roll and pitch around turns.

    Because the detector system has a high center of gravity — about 10 feet up — engineers needed to ensure that the route did not include any inclines or turn angles that would change the level of the trailer more than 5 degrees.

    “During transportation, we needed to keep everything aligned,” said Monica Nunes, a guest scientist who coordinated the SBND assembly. “The detector was built to be transported, but a move like this — with a system that has such a high center of gravity — has never been done at Fermilab before.”

    4
    The detector was wrapped in protective coverings prior to its move. Photo: Ryan Postel, Fermilab.

    The data showed that the preferred route was along Fermilab’s Ring Road. At a maximum speed of about 2.5 miles per hour, and with an escort from Fermilab security, this part of the transport was expected to take about 90 minutes. Scientists and engineers walked alongside the truck as it moved, monitoring the load real-time with accelerators and inclinometers that transmitted data to their cell phones.

    The route had been well prepared. In the days before the move, Fermilab’s Infrastructure Services Division inspected the road for potholes, trimmed trees and removed powerlines to ready the route.

    “Many people at Fermilab have worked together to make this happen — physicists, students, technical staff, administration, procurement,” said Anne Schukraft, neutrino scientist and SBND technical coordinator. “It has been great to get everyone’s input and to learn from everyone’s expertise. It has been a true team effort.”

    After the move

    Once the detector system arrived at the detector hall, the crane unloaded it from the trailer and placed it on steel tracks for it to be rolled 82 feet into the detector hall. That completed the move for the day.

    In the coming days and weeks, Fermilab scientists and engineers will unwrap the detector, set up outriggers, and install fall protection to be able to work safely on top of the detector. They will also test each of the subsystems to ensure they were not compromised during the move.

    In the coming months, the detector will be fitted with a top cap and placed inside the cryostat. Next summer, the cryostat will be filled with liquid argon. Scientists will test the system to characterize the signals it receives before it begins receiving real data from the neutrino beam in the fall of 2023. Ultimately, SBND will record over a million neutrino interactions per year.

    “To finally have data will be really exciting,” Palamara said. “We have been working toward this for eight years.”

    See the full article here .

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The DOE’s Fermi National Accelerator Laboratory, located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association. Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL)[CERN] Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    NOνA (NuMI Off-Axis νe Appearance)

    and Seaquest

    .

    Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment).

    The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year.

    SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector.

    The ICARUS neutrino experiment was moved from CERN to Fermilab.

    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.

    Asteroid 11998 Fermilab is named in honor of the laboratory.

    The DOE’s Fermi National Accelerator Laboratory campus.

    The DOE’s Fermi National Accelerator Laboratory/MINERvA. Photo Reidar Hahn.

    The DOE’s Fermi National Accelerator LaboratoryDAMIC | The Fermilab Cosmic Physics Center.

    The DOE’s Fermi National Accelerator LaboratoryMuon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

    The DOE’s Fermi National Accelerator Laboratory Short-Baseline Near Detector under construction.

    The DOE’s Fermi National Accelerator Laboratory Mu2e solenoid.

    The Dark Energy Camera [DECam], built at The DOE’s Fermi National Accelerator Laboratory.

    Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.

    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.

    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid and hosts 1000 U.S. scientists who work on the CMS project.

    FNAL Icon

     
  • richardmitnick 8:36 am on November 11, 2022 Permalink | Reply
    Tags: "Ghost particles caught streaming from dust-shrouded black hole", , , , , Blazars are prime candidates for generating neutrinos., , , Messier 77 has a magnetic field that is acting as a powerful particle accelerator., , Neutrinos, Neutrinos are not rare — roughly 100 trillion of them pass through your body every second., Neutrinos barely interact with matter., , The IceCube observatory in Antarctica has captured the best evidence yet that the galactic core of M77 is producing neutrinos.   

    From “Astronomy Magazine” : “Ghost particles caught streaming from dust-shrouded black hole” 

    From “Astronomy Magazine”

    11.7.22
    Mark Zastrow

    The IceCube observatory in Antarctica has captured the best evidence yet that the galactic core of Messier 77 is producing neutrinos.

    __________________________________________________

    U Wisconsin IceCube neutrino observatory

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

    Lunar Icecube.

    IceCube Gen-2 DeepCore PINGU annotated.

    IceCube neutrino detector interior.

    IceCube DeepCore annotated.

    DM-Ice II at IceCube annotated.


    __________________________________________________

    2
    The active galaxy Messier 77 as captured by the Hubble Space Telescope. Credit: A. van der Hoeven/The National Aeronautics and Space Agency/ The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganization](EU).

    The origins of neutrinos are notoriously hard to pin down. The cosmos is flooded by these ghostlike particles, which come from all over the sky. But for years, neutrinos’ elusive nature meant astronomers could point confidently to just one galaxy known to produce them.

    Now, there is strong evidence for a second: the bright spiral Messier 77 (NGC 1068) in Cetus. In a paper published Nov. 3 in Science [below], researchers report fresh observations from the IceCube neutrino observatory at the South Pole, plus improved analysis techniques that draw on machine learning. Combined, the results point to Messier 77 as the origin of 79 neutrinos that IceCube has detected over the past decade.

    That interpretation suggests that the supermassive black hole at the dust-obscured heart of Messier 77 has a magnetic field that is acting as a powerful particle accelerator. But it also hints at answers to a larger astronomical mystery: how neutrinos are produced and how that process relates to other high-energy forms of light and matter that astronomers detect in the sky — cosmic rays and gamma rays.

    In Messier 77, IceCube could be getting a glimpse of the origin of cosmic rays, says Francis Halzen, IceCube’s principal investigator and a particle physicist at the University of Wisconsin-Madison. In any case, Halzen is optimistic that more results will be forthcoming: “I think that we have the tools to solve the oldest problem in astronomy.”

    Elusive particles

    Theory predicts that neutrinos originate in some of the most energetic and violent regions of space: for instance, the cores of galaxies, when cosmic rays run into dust and radiation. The radioactive debris of such collisions eventually decays into neutrinos and gamma rays.

    Observing this, however, is not easy. Neutrinos are not rare — roughly 100 trillion of them pass through your body every second. The difficulty is that unlike light, which is easily reflected or bent by mirrors and lenses, neutrinos barely interact with matter. A neutrino could travel through lead for a light-year before having a 50 percent chance of interacting with an atom.

    In 2017, IceCube played a pivotal role in one of the first examples of a multi-messenger astronomy campaign, when the observatory detected a particularly energetic neutrino coming from a point in Orion. Follow-up observations from ground- and space-based telescopes — including NASA’s Fermi gamma-ray telescope — working across the electromagnetic spectrum showed that the neutrino likely came from a known blazar, TXS 0506+056, that was in the middle of producing a flare of gamma rays.


    Blazars are prime candidates for generating neutrinos: They have central supermassive black holes spitting out jets of material at near-light speed aligned directly at Earth. However, the amount of neutrinos that IceCube has detected from TXS 0506+056 is much less than astronomers would expect if blazars were the sole source for all neutrinos seen across the sky.

    This led astronomers to suspect that other types of galaxy could be producing neutrinos, too — ones whose gamma rays are “hidden,” perhaps obscured. An analysis of IceCube data published in 2020 [Physical Review Letters (below)]tentatively identified one such candidate galaxy: M77 in Cetus, roughly 30 million to 60 million light-years away. It appeared to be the source of dozens of neutrinos, despite the fact that its core lacks the powerful jets seen in blazars. It is “a clear example of such [a] gamma-ray obscured cosmic-ray accelerator,” Khota Murase, an astrophysicst at Penn State University who was not involved in the work, told Astronomy via email.

    3
    This sky map produced from IceCube data depicts neutrino sources by the probability that they are not false positives. The circled spot in the northern hemisphere is Messier 77 — the most probable detection in the northern sky. Credit: IceCube Collaboration.

    But the evidence as of 2020 wasn’t strong enough for the IceCube team to claim Messier 77 as a clear detection; according to the team’s analysis, the statistical significance was 2.9σ, meaning there was roughly a 1-in-500 chance that the build-up of neutrinos from Messier 77’s location could be a random occurrence. It left open the question, “Was this real, or were these fluctuations?” says Halzen. But with the new paper, he says, “we have now answered this question.”

    Improved analysis

    The new analysis includes a bevy of improvements, including machine-learning techniques to improve the accuracy of the neutrino tracks and their energies. The team says it also has a better understanding of the optical properties of the ice and IceCube’s directional sensitivity to neutrinos. These factors push the statistical significance of the find up to 4.2 σ. This is still short of the 5σ threshold that is considered the gold standard in physics, which equates to a probability that the signal could be a random error of just 1 in 3.5 million. Still, it is “great progress,” says Murase, who also penned a commentary for Science [below] accompanying the paper.

    IceCube plans to keep up its momentum. During the South Pole summer season spanning 2025 and 2026, the observatory will be upgraded with more sensors and new calibration devices. The additions will improve the telescope’s sensitivity and also allow for another improved reanalysis of 15 years of data, says Halzen.

    The team has also proposed a next-gen version of IceCube with eight times the volume of the current observatory, which would be capable of confirming sources like Messier 77 at the 5σ level and was endorsed by last year’s astronomy decadal survey.

    Science papers:
    Science
    Physical Review Letters 2020
    See this science paper for detailed material with images if the reader has proper credentials.
    Commentary for Science

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Astronomy is a magazine about the science and hobby of Astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of The University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at The University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However, he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 4:59 pm on November 3, 2022 Permalink | Reply
    Tags: , , , , , IceCube has accumulated some 80 neutrinos of "TeV" [tera electron volt] energy from NGC 1068 which are not yet enough to answer all science questions., , Neutrinos, Neutrinos are set to lead a new era of discovery in astronomy., Neutrinos escape in large numbers from extremely dense environments in the universe and reach Earth largely undisturbed by matter and the electromagnetic fields that permeate extragalactic space., NGC 1068 could become a "standard candle" for future neutrino telescopes., NGC 1068 is an active galaxy where most radiation is produced due to material falling into a black hole millions of times more massive than our Sun and even more massive than SGR A*., NGC 1068 is an active galaxy—a Seyfert II type., NGC 1068-also known as Messier 77-an active galaxy in the constellation Cetus, Only an observation with multiple neutrinos will reveal the obscured core of the most energetic cosmic objects., , The University of Wisconsin-Madison IceCube Collaboration, The weak interaction of neutrinos with matter and radiation makes their detection extremely difficult., This neutrino detection from the core of NGC 1068 will improve our understanding of the environments around supermassive black holes.   

    From The University of Wisconsin-Madison IceCube Collaboration : “IceCube neutrinos give us first glimpse into the inner depths of an active galaxy” 

    From The University of Wisconsin-Madison IceCube Collaboration

    11.3.22
    Science contacts:

    Francis Halzen, IceCube Principal Investigator
    Vilas Research Professor and Gregory Breit Distinguished Professor of Physics
    Wisconsin IceCube Particle Astrophysics Center
    University of Wisconsin–Madison
    francis.halzen@icecube.wisc.edu

    Ignacio Taboada,
    IceCube Spokesperson
    Professor of Physics
    Georgia Institute of Technology
    taboada@gatech.edu

    Elisa Resconi
    Professor of physics and lead scientist
    Technical University of Munich
    elisa.resconi@tum.de

    Press contact:

    IceCube Press
    press@icecube.wisc.edu
    608-515-3831

    NSF Media Affairs
    media@nsf.gov
    703-292-7090

    For the first time, an international team of scientists have found evidence of high-energy neutrino emission from NGC 1068, also known as Messier 77, an active galaxy in the constellation Cetus and one of the most familiar and well-studied galaxies to date. First spotted in 1780, this galaxy, located 47 million light-years away from us, can be observed with large binoculars. The results, to be published tomorrow (Nov. 4, 2022) in Science [below], were shared today in an online scientific webinar that gathered experts, journalists, and scientists from around the globe.

    1
    Hubble image of the spiral galaxy NGC 1068. Credit: A. van der Hoeven/NASA/ESA.

    The detection was made at the National Science Foundation-supported IceCube Neutrino Observatory, a massive neutrino telescope encompassing 1 billion tons of instrumented ice at depths of 1.5 to 2.5 kilometers below Antarctica’s surface near the South Pole [images below]. This unique telescope, which explores the farthest reaches of our universe using neutrinos, reported the first observation of a high-energy astrophysical neutrino source in 2018. The source, TXS 0506+056, is a known blazar located off the left shoulder of the Orion constellation and 4 billion light-years away.

    “One neutrino can single out a source. But only an observation with multiple neutrinos will reveal the obscured core of the most energetic cosmic objects,” says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator of IceCube. He adds, “IceCube has accumulated some 80 neutrinos of “TeV” [tera electron volt] energy from NGC 1068, which are not yet enough to answer all our questions, but they definitely are the next big step towards the realization of neutrino astronomy.”

    3
    Munchen Group
    From left to right: Martin Wolf (TUM), Hans Niederhausen (TUM), Elisa Resconi (TUM), Chiara Bellenghi (TUM), Francis Halzen (UW–Madison), and Tomas Kontrimas (TUM). Credit: Yuya Makino, IceCube/NSF

    Unlike light, neutrinos can escape in large numbers from extremely dense environments in the universe and reach Earth largely undisturbed by matter and the electromagnetic fields that permeate extragalactic space. Although scientists envisioned neutrino astronomy more than 60 years ago, the weak interaction of neutrinos with matter and radiation makes their detection extremely difficult. Neutrinos could be key to our queries about the workings of the most extreme objects in the cosmos.

    “Answering these far-reaching questions about the universe that we live in is a primary focus of the U.S. National Science Foundation,” says Denise Caldwell, director of NSF’s Physics Division.

    As is the case with our home galaxy, the Milky Way, NGC 1068 is a barred spiral galaxy, with loosely wound arms and a relatively small central bulge. However, unlike the Milky Way, NGC 1068 is an active galaxy where most radiation is not produced by stars but due to material falling into a black hole millions of times more massive than our Sun and even more massive than the inactive black hole in the center of our galaxy.

    NGC 1068 is an active galaxy—a Seyfert II type in particular—seen from Earth at an angle that obscures its central region where the black hole is located. In a Seyfert II galaxy, a torus of nuclear dust obscures most of the high-energy radiation produced by the dense mass of gas and particles that slowly spiral inward toward the center of the galaxy.

    “Recent models of the black hole environments in these objects suggest that gas, dust, and radiation should block the gamma rays that would otherwise accompany the neutrinos,” says Hans Niederhausen, a postdoctoral associate at Michigan State University and one of the main analyzers of the paper. “This neutrino detection from the core of NGC 1068 will improve our understanding of the environments around supermassive black holes.”

    NGC 1068 could become a “standard candle” for future neutrino telescopes, according to Theo Glauch, a postdoctoral associate at the Technical University of Munich (TUM), in Germany, and another main analyzer.

    “It is already a very well-studied object for astronomers, and neutrinos will allow us to see this galaxy in a totally different way. A new view will certainly bring new insights,” says Glauch.

    These findings represent a significant improvement on a prior study on NGC 1068 published in 2020, according to Ignacio Taboada, a physics professor at the Georgia Institute of Technology and the spokesperson of the IceCube Collaboration.

    “Part of this improvement came from enhanced techniques and part from a careful update of the detector calibration,” says Taboada. “Work by the detector operations and calibrations teams enabled better neutrino directional reconstructions to precisely pinpoint NGC 1068 and enable this observation. Resolving this source was made possible through enhanced techniques and refined calibrations, an outcome of the IceCube Collaboration’s hard work.”

    The improved analysis points the way toward superior neutrino observatories that are already in the works.

    “It is great news for the future of our field,” says Marek Kowalski, an IceCube collaborator and senior scientist at Deutsches Elektronen-Synchrotron [DESY], in Germany. “It means that with a new generation of more sensitive detectors there will be much to discover. The future IceCube-Gen2 observatory could not only detect many more of these extreme particle accelerators but would also allow their study at even higher energies. It’s as if IceCube handed us a map to a treasure trove.”

    4
    Brussels 2022
    The IceCube Collaboration, spring 2022. Credit: IceCube Collaboration

    With the neutrino measurements of TXS 0506+056 and NGC 1068, IceCube is one step closer to answering the century-old question of the origin of cosmic rays.

    Additionally, these results imply that there may be many more similar objects in the universe yet to be identified.

    “The unveiling of the obscured universe has just started, and neutrinos are set to lead a new era of discovery in astronomy,” says Elisa Resconi, a professor of physics at TUM and another main analyzer.

    “Several years ago, NSF initiated an ambitious project to expand our understanding of the universe by combining established capabilities in optical and radio astronomy with new abilities to detect and measure phenomena like neutrinos and gravitational waves,” says Caldwell. “The IceCube Neutrino Observatory’s identification of a neighboring galaxy as a cosmic source of neutrinos is just the beginning of this new and exciting field that promises insights into the undiscovered power of massive black holes and other fundamental properties of the universe.”

    Science paper:
    Science

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino.

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

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

    Lunar Icecube.

    IceCube Gen-2 DeepCore PINGU annotated.

    IceCube neutrino detector interior.

    IceCube DeepCore annotated.

     
  • richardmitnick 10:17 pm on October 24, 2022 Permalink | Reply
    Tags: "Mainz team of scientists provides insight into the diffuse ice of Antarctica", Anisotropy, , Ice crystal properties are investigated in particular in order to understand the mechanics of ice flow. This is the basis for predicting the Antarctic mass balance and the rise in sea level., In order to use this new discovery in the study of cosmic neutrinos the IceCube collaboration created new simulations and adapted the current reconstruction methods., Neutrinos, , The IceCube collaboration reports a new optical effect for the first time. It is the result of the birefringent properties of elongated ice crystals., , This new understanding will not only help IceCube to better reconstruct neutrino interactions but also has implications for the field of glaciology.,   

    From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Mainz team of scientists provides insight into the diffuse ice of Antarctica” 

    From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

    10.21.22

    Since 2010, the IceCube Neutrino Observatory at the South Pole has been searching for high-energy neutrinos from space. The experiment consists of 5,160 optical sensors, the so-called digital optical modules (DOMs), which are sunk up to 2.5 kilometers deep in one cubic kilometer of Antarctic ice.
    _____________________________________________________
    U Wisconsin IceCube Neutrino Observatory

    U Wisconsin IceCube Neutrino Observatory neutrino detector at the at the Amundsen-Scott South Pole Station in Antarctica South Pole, elevation of 2,835 metres (9,301 feet).
    IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration.

    Lunar Icecube

    IceCube Gen-2 DeepCore PINGU annotated

    IceCube neutrino detector interior.

    IceCube DeepCore annotated.

    DM-Ice II at IceCube annotated.


    _____________________________________________________

    When a neutrino interacts with a molecule in the ice, characteristic blue Čerenkov light is produced. This travels through the ice and can reach some of the DOMs where it is detected. The researchers can then reconstruct the energy and direction of the original neutrino – a process based on knowledge of the optical properties of the ice. In 2013, the IceCube collaboration reported a unique observation in which the brightness of a light source in the ice depends on the direction of the light from which it is observed. So far, researchers have tried to describe this so-called anisotropy with variations in the absorption and scattering caused by impurities, but so far with limited success.

    In a recent study published in the journal The Cryosphere Discussions [below], the IceCube collaboration reports a new optical effect for the first time. It is the result of the birefringent properties of elongated ice crystals. The newly gained insights have been incorporated into a new birefringence-based optical model of the ice, which has significantly improved the interpretation of the light patterns resulting from particle interactions in the ice.

    2
    ©: Jack Pairin / IceCube Collaboration
    Without birefringence (top), the light flows radially from an isotropic light source. With birefringence (bottom), the light is slowly deflected towards the ice flow axis.

    To improve previous attempts to simulate anisotropy, the researchers studied the anisotropy effect in more detail. Their results led them to believe that the many randomly arranged small crystals that make up the ice, and not just impurities it contains, play a role in the observed anisotropy.

    “Then we realized that assuming curved light paths with tiny deflections of less than one degree per meter, we can suddenly accurately describe the IceCube data. This really got things rolling,” says Dr. Martin Rongen, researcher at the PRISMA Cluster of Excellence.+ Johannes Gutenberg University Mainz (JGU) and is in charge of the current analysis. “The next question was: How does this curvature come about? The answer lies in the microstructure of the ice: indeed, when calculating and simulating the light scattering by birefringent polycrystalline ice, as occurs in IceCube and where the crystals are stretched on average along the direction of flow of the ice, such a deflection results.”

    For the study, the researchers simulated many different paths that light could travel within the IceCube detector – based on thousands of different crystal configurations in the ice. They then compared the simulated data with a large calibration data set. This includes data from 60,000 LEDs attached to all DOMs that emit consistent light pulses into the ice. From the comparison, the researchers were able to draw conclusions about the average shape and size of the ice crystals in IceCube.

    In order to use this new discovery in the study of cosmic neutrinos, the IceCube collaboration created new simulations and adapted the current reconstruction methods. This new understanding will not only help IceCube to better reconstruct neutrino interactions, but also has implications for the field of glaciology.

    “I am fascinated by the idea of understanding ice from the ground up,” says Dr. Martin Rongen. “Ice crystal properties are investigated in particular in order to understand the mechanics of ice flow. This in turn is the basis for predicting the Antarctic mass balance and the resulting rise in sea level in a changing climate.”

    Science paper:
    The Cryosphere Discussions

    See the full article here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

    The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

    The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities [Rhein-Main Universitäten](DE)(RMU).

    The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

    The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

    The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

    In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

     
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