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  • richardmitnick 9:22 pm on April 15, 2021 Permalink | Reply
    Tags: "IceCube Neutrino Observatory Detects New High-Energy Particle", , , , , U Wisconsin IceCube and IceCube Gen-2,   

    From UC San Diego: “IceCube Neutrino Observatory Detects New High-Energy Particle” 

    From UC San Diego

    April 15, 2021
    Cynthia Dillon
    858-822-6673
    cdillon@ucsd.edu

    1
    A visualization of the Glashow event recorded by the IceCube detector. Each colored circle shows an IceCube sensor that was triggered by the event; red circles indicate sensors triggered earlier in time, and green-blue circles indicate sensors triggered later. This event was nicknamed “Hydrangea.” Credit: IceCube Neutrino Observatory at the South Pole (US).

    In December 2016, a high-energy particle called an electron antineutrino hurtled to Earth from outer space at close to the speed of light. Deep inside the ice sheet at the South Pole, it smashed into an electron and produced a particle, called W− boson, that quickly decayed into a shower of secondary particles. The interaction was captured by a massive telescope buried in the Antarctic glacier, the IceCube Neutrino Observatory (IceCube).

    U Wisconsin IceCube neutrino observatory

    U Wisconsin IceCube Neutrino Observatory(US) 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 DeepCore annotated .

    IceCube neutrino detector interior.

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

    Lunar Icecube.

    IceCube DeepCore annotated.

    IceCube PINGU annotated.

    DM-Ice II at IceCube annotated.

    IceCube Gen-2 DeepCore PINGU annotated.

    DM-Ice II at IceCube annotated.

    IceCube had detected a Glashow resonance event, a phenomenon predicted by Nobel Laureate Physicist Sheldon Glashow in 1960. With this detection, scientists provided another confirmation of the Standard Model of particle physics.

    It also further demonstrated the ability of IceCube, which detects nearly massless particles called neutrinos using thousands of sensors embedded in the Antarctic ice, to do fundamental physics. The result recently published in Nature is so important because it shows that IceCube can detect anti-neutrinos as different from neutrinos, thus opening a new window to the universe.

    The multinational team of scientists—including researchers from UC Irvine (US) and UC Berkeley (US)—searched for very-high-energy astrophysical neutrinos with IceCube. Using San Diego Supercomputer Center’s (SDSC) Comet at UC San Diego, Bridges at Pittsburgh Supercomputing Center (PSC), and Frontera at Texas Advanced Computing Center (TACC), one interaction of one antineutrino (known as an “event”) was found with a visible energy of 6.05 ± 0.72 PeV.

    San Diego Supercomputer Center Dell Comet supercomputer.

    Bridges HPE Apollo 2000 XSEDE-allocated supercomputer at Pittsburgh Supercomputing Center.

    University of Texas at Austin-Texas Advanced Computing Center Frontera Dell EMC supercomputer fastest at any university.

    Given its energy and direction, it is classified as an astrophysical neutrino at the 5σ level. Furthermore, data collected by the sensors closest to the interaction point, as well as the measured energy, are consistent with the hadronic decay of a W− boson produced on the Glashow resonance as outlined in the 1960 prediction. The latter unambiguously identifies the incoming particle as an anti-neutrino rather than a neutrino, or anti-matter rather than matter.


    IceCube Neutrino Observatory Detects New High-Energy Particle.

    “To simulate this detection, our IceCube collaborators used millions of hours on multiple supercomputers to sort through the data, understand the detector response and calculate the direction of origin for this particular anti-neutrino,” explained Frank Würthwein, a UC San Diego physics professor and executive director of the Open Science Grid (OSG) at SDSC. “We were excited about the detection and fortunate that our resources could support this groundbreaking science.”

    Würthwein has been working closely with the observatory’s Global Computing Manager Benedickt Riedel and an international team of scientists for the past decade.

    “Constructing a comparable observatory anywhere else would have been astronomically expensive,” said Riedel. “Antarctica ice provides us with the perfect optical material and we moved from the traditional view of a guy with a telescope looking up at the sky to large-scale instruments and now on to particle physics and particle observatories.”

    Riedel explained that with this new paradigm, large amounts of computing for short periods of time to do big time-sensitive computing was needed, with big scientific computing centers like TACC, SDSC, and PSC.

    While these supercomputer resource allocations were funded by the National Science Foundation’s Extreme Science and Engineering Environment , additional computing resources included the OSG and the Pacific Research Platform (PRP), partnerships of more than 100 institutions led by researchers at UC San Diego, and that include NSF- and Department of Energy (US)-funded resources, and multiple research universities around the world.

    San Diego Supercomputer Center Among Resources Used to Prove 60-Year-Old Theory.

    San Diego Supercomputer Center

    SDSC Triton HP supercomputer

    SDSC Gordon-Simons supercomputer

    SDSC Dell Comet supercomputer

    See the full article here .

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    Please help promote STEM in your local schools.

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    The University of California, San Diego, is a public research university located in the La Jolla area of San Diego, California, in the United States. The university occupies 2,141 acres (866 ha) near the coast of the Pacific Ocean with the main campus resting on approximately 1,152 acres (466 ha). Established in 1960 near the pre-existing Scripps Institution of Oceanography, UC San Diego is the seventh oldest of the 10 University of California campuses and offers over 200 undergraduate and graduate degree programs, enrolling about 22,700 undergraduate and 6,300 graduate students. UC San Diego is one of America’s Public Ivy universities, which recognizes top public research universities in the United States. UC San Diego was ranked 8th among public universities and 37th among all universities in the United States, and rated the 18th Top World University by U.S. News & World Report’s 2015 rankings.

    UC San Diego is organized into seven undergraduate residential colleges (Revelle; John Muir; Thurgood Marshall; Earl Warren; Eleanor Roosevelt; Sixth; and Seventh), four academic divisions (Arts and Humanities; Biological Sciences; Physical Sciences; and Social Sciences), and seven graduate and professional schools (Jacobs School of Engineering; Rady School of Management; Scripps Institution of Oceanography; School of Global Policy and Strategy; School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences; and the newly established Wertheim School of Public Health and Human Longevity Science). UC San Diego Health, the region’s only academic health system, provides patient care; conducts medical research; and educates future health care professionals at the UC San Diego Medical Center, Hillcrest; Jacobs Medical Center; Moores Cancer Center; Sulpizio Cardiovascular Center; Shiley Eye Institute; Institute for Genomic Medicine; Koman Family Outpatient Pavilion and various express care and urgent care clinics throughout San Diego.

    The university operates 19 organized research units (ORUs), including the Center for Energy Research; Qualcomm Institute (a branch of the California Institute for Telecommunications and Information Technology); San Diego Supercomputer Center; and the Kavli Institute for Brain and Mind, as well as eight School of Medicine research units, six research centers at Scripps Institution of Oceanography and two multi-campus initiatives, including the Institute on Global Conflict and Cooperation. UC San Diego is also closely affiliated with several regional research centers, such as the Salk Institute; the Sanford Burnham Prebys Medical Discovery Institute; the Sanford Consortium for Regenerative Medicine; and the Scripps Research Institute. It is classified among “R1: Doctoral Universities – Very high research activity”. According to the National Science Foundation(US), UC San Diego spent $1.265 billion on research and development in fiscal year 2018, ranking it 7th in the nation.

    UC San Diego is considered one of the country’s Public Ivies. As of February 2021, UC San Diego faculty, researchers and alumni have won 27 Nobel Prizes and three Fields Medals, eight National Medals of Science, eight MacArthur Fellowships, and three Pulitzer Prizes. Additionally, of the current faculty, 29 have been elected to the National Academy of Engineering, 70 to the National Academy of Sciences(US), 45 to the National Academy of Medicine(US) and 110 to the American Academy of Arts and Sciences.

    History

    When the Regents of the University of California originally authorized the San Diego campus in 1956, it was planned to be a graduate and research institution, providing instruction in the sciences, mathematics, and engineering. Local citizens supported the idea, voting the same year to transfer to the university 59 acres (24 ha) of mesa land on the coast near the preexisting Scripps Institution of Oceanography(US). The Regents requested an additional gift of 550 acres (220 ha) of undeveloped mesa land northeast of Scripps, as well as 500 acres (200 ha) on the former site of Camp Matthews from the federal government, but Roger Revelle, then director of Scripps Institution and main advocate for establishing the new campus, jeopardized the site selection by exposing the La Jolla community’s exclusive real estate business practices, which were antagonistic to minority racial and religious groups. This outraged local conservatives, as well as Regent Edwin W. Pauley.

    UC President Clark Kerr satisfied San Diego city donors by changing the proposed name from University of California, La Jolla, to University of California, San Diego. The city voted in agreement to its part in 1958, and the UC approved construction of the new campus in 1960. Because of the clash with Pauley, Revelle was not made chancellor. Herbert York, first director of Lawrence Livermore National Laboratory, was designated instead. York planned the main campus according to the “Oxbridge” model, relying on many of Revelle’s ideas.

    According to Kerr, “San Diego always asked for the best,” though this created much friction throughout the UC system, including with Kerr himself, because UC San Diego often seemed to be “asking for too much and too fast.” Kerr attributed UC San Diego’s “special personality” to Scripps, which for over five decades had been the most isolated UC unit in every sense: geographically, financially, and institutionally. It was a great shock to the Scripps community to learn that Scripps was now expected to become the nucleus of a new UC campus and would now be the object of far more attention from both the university administration in Berkeley and the state government in Sacramento.

    UC San Diego was the first general campus of the University of California to be designed “from the top down” in terms of research emphasis. Local leaders disagreed on whether the new school should be a technical research institute or a more broadly based school that included undergraduates as well. John Jay Hopkins of General Dynamics Corporation pledged one million dollars for the former while the City Council offered free land for the latter. The original authorization for the San Diego campus given by the UC Regents in 1956 approved a “graduate program in science and technology” that included undergraduate programs, a compromise that won both the support of General Dynamics and the city voters’ approval.

    Nobel laureate Harold Urey, a physicist from the University of Chicago(US), and Hans Suess, who had published the first paper on the greenhouse effect with Revelle in the previous year, were early recruits to the faculty in 1958. Maria Goeppert-Mayer, later the second female Nobel laureate in physics, was appointed professor of physics in 1960. The graduate division of the school opened in 1960 with 20 faculty in residence, with instruction offered in the fields of physics, biology, chemistry, and earth science. Before the main campus completed construction, classes were held in the Scripps Institution of Oceanography.

    By 1963, new facilities on the mesa had been finished for the School of Science and Engineering, and new buildings were under construction for Social Sciences and Humanities. Ten additional faculty in those disciplines were hired, and the whole site was designated the First College, later renamed after Roger Revelle, of the new campus. York resigned as chancellor that year and was replaced by John Semple Galbraith. The undergraduate program accepted its first class of 181 freshman at Revelle College in 1964. Second College was founded in 1964, on the land deeded by the federal government, and named after environmentalist John Muir two years later. The School of Medicine also accepted its first students in 1966.

    Political theorist Herbert Marcuse joined the faculty in 1965. A champion of the New Left, he reportedly was the first protester to occupy the administration building in a demonstration organized by his student, political activist Angela Davis. The American Legion offered to buy out the remainder of Marcuse’s contract for $20,000; the Regents censured Chancellor William J. McGill for defending Marcuse on the basis of academic freedom, but further action was averted after local leaders expressed support for Marcuse. Further student unrest was felt at the university, as the United States increased its involvement in the Vietnam War during the mid-1960s, when a student raised a Viet Minh flag over the campus. Protests escalated as the war continued and were only exacerbated after the National Guard fired on student protesters at Kent State University in 1970. Over 200 students occupied Urey Hall, with one student setting himself on fire in protest of the war.

    Early research activity and faculty quality, notably in the sciences, was integral to shaping the focus and culture of the university. Even before UC San Diego had its own campus, faculty recruits had already made significant research breakthroughs, such as the Keeling Curve, a graph that plots rapidly increasing carbon dioxide levels in the atmosphere and was the first significant evidence for global climate change; the Kohn–Sham equations, used to investigate particular atoms and molecules in quantum chemistry; and the Miller–Urey experiment, which gave birth to the field of prebiotic chemistry.

    Engineering, particularly computer science, became an important part of the university’s academics as it matured. University researchers helped develop UCSD Pascal, an early machine-independent programming language that later heavily influenced Java; the National Science Foundation Network, a precursor to the Internet; and the Network News Transfer Protocol during the late 1970s to 1980s. In economics, the methods for analyzing economic time series with time-varying volatility (ARCH), and with common trends (cointegration) were developed. UC San Diego maintained its research intense character after its founding, racking up 25 Nobel Laureates affiliated within 50 years of history; a rate of five per decade.

    Under Richard C. Atkinson’s leadership as chancellor from 1980 to 1995, the university strengthened its ties with the city of San Diego by encouraging technology transfer with developing companies, transforming San Diego into a world leader in technology-based industries. He oversaw a rapid expansion of the School of Engineering, later renamed after Qualcomm founder Irwin M. Jacobs, with the construction of the San Diego Supercomputer Center(US) and establishment of the computer science, electrical engineering, and bioengineering departments. Private donations increased from $15 million to nearly $50 million annually, faculty expanded by nearly 50%, and enrollment doubled to about 18,000 students during his administration. By the end of his chancellorship, the quality of UC San Diego graduate programs was ranked 10th in the nation by the National Research Council.

    The university continued to undergo further expansion during the first decade of the new millennium with the establishment and construction of two new professional schools — the Skaggs School of Pharmacy and Rady School of Management—and the California Institute for Telecommunications and Information Technology, a research institute run jointly with University of California Irvine(US). UC San Diego also reached two financial milestones during this time, becoming the first university in the western region to raise over $1 billion in its eight-year fundraising campaign in 2007 and also obtaining an additional $1 billion through research contracts and grants in a single fiscal year for the first time in 2010. Despite this, due to the California budget crisis, the university loaned $40 million against its own assets in 2009 to offset a significant reduction in state educational appropriations. The salary of Pradeep Khosla, who became chancellor in 2012, has been the subject of controversy amidst continued budget cuts and tuition increases.

    On November 27, 2017, the university announced it would leave its longtime athletic home of the California Collegiate Athletic Association, an NCAA Division II league, to begin a transition to Division I in 2020. At that time, it will join the Big West Conference, already home to four other UC campuses (Davis, Irvine, Riverside, Santa Barbara). The transition period will run through the 2023–24 school year. The university prepares to transition to NCAA Division I competition on July 1, 2020.

    Research

    Applied Physics and Mathematics

    The Nature Index lists UC San Diego as 6th in the United States for research output by article count in 2019. In 2017, UC San Diego spent $1.13 billion on research, the 7th highest expenditure among academic institutions in the U.S. The university operates several organized research units, including the Center for Astrophysics and Space Sciences (CASS), the Center for Drug Discovery Innovation, and the Institute for Neural Computation. UC San Diego also maintains close ties to the nearby Scripps Research Institute(US) and Salk Institute for Biological Studies(US). In 1977, UC San Diego developed and released the UCSD Pascal programming language. The university was designated as one of the original national Alzheimer’s disease research centers in 1984 by the National Institute on Aging. In 2018, UC San Diego received $10.5 million from the DOE National Nuclear Security Administration(US) to establish the Center for Matters under Extreme Pressure (CMEC).

    The university founded the San Diego Supercomputer Center (SDSC) in 1985, which provides high performance computing for research in various scientific disciplines. In 2000, UC San Diego partnered with UC Irvine to create the Qualcomm Institute – UC San Diego(US), which integrates research in photonics, nanotechnology, and wireless telecommunication to develop solutions to problems in energy, health, and the environment.

    UC San Diego also operates the Scripps Institution of Oceanography (SIO)(US), one of the largest centers of research in earth science in the world, which predates the university itself. Together, SDSC and SIO, along with funding partner universities California Institute of Technology(US), San Diego State University(US), and UC Santa Barbara, manage the High Performance Wireless Research and Education Network.

     
  • richardmitnick 4:09 pm on February 26, 2020 Permalink | Reply
    Tags: "Radio waves detect particle showers in a block of plastic", SLAC End Station A (ESA) - End Station Test Beam (ESTB), , U Wisconsin IceCube and IceCube Gen-2   

    From SLAC National Accelerator Lab: “Radio waves detect particle showers in a block of plastic” 

    From SLAC National Accelerator Lab

    February 24, 2020
    Ali Sundermier

    1
    Credit: SLAC National Accelerator Laboratory

    A cheap technique could detect neutrinos in polar ice, eventually allowing researchers to expand the energy reach of IceCube without breaking the bank.

    When neutrinos crash into water molecules in the billion-plus tons of ice that make up the detector at the IceCube Neutrino Observatory in Antarctica, more than 5,000 sensors detect the light of subatomic particles produced by the collisions. But as one might expect, these grand-scale experiments don’t come cheap.

    U Wisconsin IceCube neutrino observatory

    1

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

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated

    DM-Ice II at IceCube annotated


    In a paper recently accepted by Physical Review Letters, an international team of physicists working at the Department of Energy’s SLAC National Accelerator Laboratory demonstrated an inexpensive way to expand IceCube’s neutrino search.

    The researchers directed an electron beam diverted from SLAC’s Linac Coherent Light Source (LCLS) [below] into a large block of plastic to mimic neutrinos colliding with ice. When a neutrino interacts with ice, it produces a cascade of high-energy particles that leave a trail of ionization in their wake. The same is true for electron collisions in the plastic.

    To detect those ionization trails, the team used an antenna to bounce radio waves off them. This created radar echoes that were picked up by additional antennas. It was the first time researchers have been able to detect radar echoes from a particle cascade.

    2
    After blasting a block of plastic with an electron beam, a team of researchers used an assortment of donated antennas to detect radar echoes from the resulting particle cascades. (Steven Prohira.)

    These echoes carry information about neutrinos in an energy range that could bridge the gap between the lower-energy neutrinos that IceCube detects and the higher-energy neutrinos detected by other in-ice and balloon-based detectors. To follow up, the researchers hope to use a similar set-up to detect neutrinos with a radio echo in Antarctic ice. If successful, the technique could eventually allow researchers to expand the energy reach of IceCube without breaking the bank.

    LCLS is a DOE Office of Science user facility. The research, carried out at the End Station A test beam (ESTB) at SLAC, was led by Steven Prohira, a postdoctoral scholar at Ohio State University.

    3
    SLAC End Station A (ESA) – End Station Test Beam (ESTB)

    Carsten Hast, a physicist at SLAC, was instrumental in setting up the experiment. The team also included researchers from the University of Kansas; California Polytechnic State University; the University of Wisconsin-Madison; Vrije Universiteit Brussel in Belgium; National Research Nuclear University, Moscow Engineering Physics Institute in Russia; and National Taiwan University. Major funding came from the DOE Office of Science.

    See the full article here .


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    Please help promote STEM in your local schools.

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    SLAC/LCLS


    SLAC/LCLS II projected view


    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 3:42 pm on February 11, 2020 Permalink | Reply
    Tags: , , U Wisconsin IceCube and IceCube Gen-2, , , Zee burst   

    From Washington University in St.Louis: “Ultra-high energy events key to study of ghost particles” 

    Wash U Bloc

    From Washington University in St.Louis

    January 31, 2020 [Just now in social media]
    Talia Ogliore

    1
    This is the highest energy neutrino ever observed, with an estimated energy of 1.14 PeV. The IceCube Neutrino Observatory at the South Pole observed it on January 3, 2012. IceCube physicists named it Ernie. (Credit: IceCube Collaboration)

    Physicists at Washington University in St. Louis have proposed a way to use data from ultra-high energy neutrinos to study interactions beyond the standard model of particle physics. The ‘Zee burst’ model leverages new data from large neutrino telescopes such as the IceCube Neutrino Observatory in Antarctica and its future extensions.

    U Wisconsin IceCube neutrino observatory

    1

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

    Lunar Icecube

    IceCube DeepCore annotated

    IceCube PINGU annotated

    DM-Ice II at IceCube annotated


    “Neutrinos continue to intrigue us and stretch our imagination. These ‘ghost particles’ are the least understood in the standard model, but they hold the key to what lies beyond,” said Bhupal Dev, assistant professor of physics in Arts & Sciences and author of a new study in Physical Review Letters.

    “So far, all nonstandard interaction studies at IceCube have focused only on the low-energy atmospheric neutrino data,” said Dev, who is part of Washington University’s McDonnell Center for the Space Sciences. “The ‘Zee burst’ mechanism provides a new tool to probe nonstandard interactions using the ultra-high energy neutrinos at IceCube.”

    Ultra-high energy events

    Since the discovery of neutrino oscillations two decades ago, which earned the 2015 Nobel Prize in physics, scientists have made significant progress in understanding neutrino properties — but a lot of questions remain unanswered.

    For example, the fact that neutrinos have such a tiny mass already requires scientists to consider theories beyond the standard model. In such theories, “neutrinos could have new nonstandard interactions with matter as they propagate through it, which will crucially affect their future precision measurements,” Dev said.

    In 2012, the IceCube collaboration reported the first observation of ultra-high energy neutrinos from extraterrestrial sources, which opened a new window to study neutrino properties at the highest possible energies. Since that discovery, IceCube has reported about 100 such ultra-high energy neutrino events.

    2
    This is the highest-energy neutrino ever observed, with an estimated energy of 1.14 PeV. It was detected by the IceCube Neutrino Observatory at the South Pole on Jan. 3, 2012. IceCube physicists named it Ernie. (Credit: IceCube collaboration)

    “We immediately realized that this could give us a new way to look for exotic particles, like supersymmetric partners and heavy decaying dark matter,” Dev said. For the previous several years, he had been looking for ways to find signals of new physics at different energy scales and had co-authored half a dozen papers studying the possibilities.

    “The common strategy I followed in all these works was to look for anomalous features in the observed event spectrum, which could then be interpreted as a possible sign of new physics,” he said.

    The most spectacular feature would be a resonance: what physicists witness as a dramatic enhancement of events in a narrow energy window. Dev devoted his time to thinking about new scenarios that could give rise to such a resonance feature. That’s where the idea for the current work came from.

    In the standard model, ultra-high energy neutrinos can produce a W-boson at resonance. This process, known as the Glashow resonance, has already been seen at IceCube, according to preliminary results presented at the Neutrino 2018 conference.

    “We propose that similar resonance features can be induced due to new light, charged particles, which provides a new way to probe nonstandard neutrino interactions,” Dev said.

    Bursting onto the neutrino scene

    Dev and his co-author Kaladi Babu at Oklahoma State University considered the Zee model, a popular model of radiative neutrino mass generation, as a prototype for their study. This model allows for charged scalars to be as light as 100 times the proton mass.

    “These light, charged Zee-scalars could give rise to a Glashow-like resonance feature in the ultra-high energy neutrino event spectrum at the IceCube Neutrino Observatory,” Dev said.

    Because the new resonance involves charged scalars in the Zee model, they decided to call it the ‘Zee burst.’

    3
    Rendering of an observation of the ultra-high energy events that feed into the ‘Zee burst’ model. (Image by Yicong Sui, Washington University)

    Yicong Sui at Washington University and Sudip Jana at Oklahoma State, both graduate students in physics and co-authors of this study, did extensive event simulations and data analysis showing that it is possible to detect such a new resonance using IceCube data.

    “We need an effective exposure time of at least four times the current exposure to be sensitive enough to detect the new resonance — so that would be about 30 years with the current IceCube design, but only three years of IceCube-Gen 2,” Dev said, referring to the proposed next-generation extension of IceCube with 10 km3 detector volume.

    “This is an effective way to look for the new charged scalars at IceCube, complementary to direct searches for these particles at the Large Hadron Collider.”

    Funding: This work was supported by US Department of Energy and by the US Neutrino Theory Network Program.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Wash U campus

    Washington University’s mission is to discover and disseminate knowledge, and protect the freedom of inquiry through research, teaching, and learning.

    Washington University creates an environment to encourage and support an ethos of wide-ranging exploration. Washington University’s faculty and staff strive to enhance the lives and livelihoods of students, the people of the greater St. Louis community, the country, and the world.

     
  • richardmitnick 12:31 am on February 6, 2020 Permalink | Reply
    Tags: "New optical telescope proves to be fit for the South Pole", , IceAct project: an array of air-Čerenkov telescopes., , , The telescopes use a camera based on semiconducting photosensors to detect Čerenkov light: radiation emitted when high-energy particles in the atmosphere travel faster than the speed of light in air., U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “New optical telescope proves to be fit for the South Pole” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From U Wisconsin IceCube Collaboration

    05 Feb 2020
    Madeleine O’Keefe

    The South Pole is a harsh environment: It’s far away from civilization, difficult to access, elevated over 9,000 feet above sea level, has practically zero percent humidity, receives no sunlight for nearly eight months—oh, and it’s freezing cold.

    For South Pole experiments like the IceCube Neutrino Observatory, all instruments—whether in the ice or on the surface—must undergo feasibility studies to make sure they can operate in the harsh Antarctic conditions. Optical instruments, especially, are subject to icing and snow accumulation. Recently, the IceCube Collaboration proved the successful operation of a new instrument, an imaging air-Čerenkov telescope, at the Pole. They outline the details of the study in a paper published yesterday in the Journal of Instrumentation.

    1
    A photo of the IceAct demonstrator telescope (white cylinder in foreground) on the roof of the IceCube Laboratory in 2016. Credit: IceCube Collaboration

    The IceCube Neutrino Observatory is an array of over 5,000 digital optical modules (DOMs) attached to cables that have been lowered into 86 holes drilled in the South Pole ice. This in-ice component is enhanced by a surface array called IceTop, which is made up of 162 tanks of frozen water that each contain two DOMs. Together, these arrays help researchers get a more complete picture of properties of high-energy particles from outer space, known as cosmic rays.

    As IceCube expands, the collaboration seeks ways to enhance the observatory’s sensitivity to particles called neutrinos that are produced by cosmic rays. Multiple detector systems have been proposed to boost IceCube’s sensitivity, one of which is the IceAct project: an array of air-Čerenkov telescopes.

    The IceAct imaging air-Čerenkov telescopes are small and cost-effective. They use a camera based on novel semiconducting photosensors to detect Čerenkov light: radiation that is emitted when high-energy particles in the atmosphere travel faster than the speed of light in air. (IceCube’s DOMs also detect Čerenkov light, but it is generated by ultrafast particles passing through ice rather than air.) “Since these particles originate from cosmic rays interacting with Earth’s atmosphere, the measurement allows a precise reconstruction of the cosmic ray air-shower properties,” says Erik Ganster of RWTH Aachen University, a lead on this study.

    By detecting this Čerenkov radiation in Earth’s atmosphere, the IceAct telescopes provide IceCube with an independent detection channel for cosmic ray-induced air showers. This additional information will allow scientists to do a number of things, including benchmarking the directional accuracy of IceCube, which is important for evaluating IceCube data quality and for improving reconstruction methods.

    IceAct would also allow scientists to measure cosmic ray composition—which is extremely important to understand and validate current models for determining the origin of cosmic rays—and improve the IceTop air shower reconstruction. Finally, IceAct would reduce the muon background that originates in air showers above IceCube by providing an air shower “veto”; this will improve the search for astrophysical neutrinos from the Southern Hemisphere.

    2
    A diagram of the IceAct demonstrator telescope. Credit: IceCube Collaboration

    With these advantages in mind, IceCube researchers had to test whether this new optical system could work jointly with IceCube. So, in January 2016, they deployed the first seven-pixel IceAct demonstrator telescope at the South Pole on top of the IceCube Laboratory, located in the center of the IceTop array above the in-ice component. It took data for several months during the 2016 Antarctic winter.

    Then, using a large set of the recorded data from that time period, researchers identified events that were detected by both IceCube and IceTop so that they could analyze the properties of coincident events and compare them. They also evaluated the camera and sensor stability as well as the dependency on atmospheric conditions to measure the stability of the data taking.

    “Overall, the demonstration was successful. We proved that the operation of optical instruments under the harsh conditions of the South Pole environment is challenging but definitely possible, which is a big achievement,” says Merlin Schaufel, also of RWTH Aachen University, another lead on this study. “We were able to prove the detection of coincident air showers together with IceTop and IceCube. From the data we found that the arrival directions are very compatible with the field of view of the telescope. The camera showed a good response stability.”

    The data showed that calibration of IceCube is feasible for a telescope with a larger camera that has better image reconstruction and greater field of view.

    “The small, lightweight, and cost-effective design of the telescope, together with the proof of its robustness, is an important step toward the installation of a large array of IceAct telescopes at the South Pole,” says Ganster. He notes that the design is also interesting for observatories other than IceCube: Prototypes have already been operated with HAWC in Mexico and H.E.S.S. in Namibia, two gamma-ray observatories.

    After the successful proof-of-concept study with the seven-pixel demonstrator telescope, the researchers have deployed a 64-pixel telescope at the South Pole in 2018 and a second in 2019, about 220 meters apart. These upgraded telescopes can record roughly the same number of events in a few hours as the demonstrator telescope was able to record in a full week. The 2019 Antarctic winter, especially, provided very promising data from the two telescopes. They are able to provide stereoscopic images of the air showers that will significantly improve the reconstruction capabilities.

    More telescopes are currently under production to be deployed in the 2020-21 and 2021-22 austral summers. Adding more telescopes will further improve the stereoscopic detection and increase the total field-of-view, which the researchers say will allow them to reach their science goals.

    See the full article here .

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    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 DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

     
  • richardmitnick 11:58 pm on February 5, 2020 Permalink | Reply
    Tags: "Optimizing the “eyeballs” of the IceCube Neutrino Observatory", , , , U Wisconsin IceCube and IceCube Gen-2,   

    From U Wisconsin IceCube Collaboration: “Optimizing the “eyeballs” of the IceCube Neutrino Observatory” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From U Wisconsin IceCube Collaboration

    05 Feb 2020
    Madeleine O’Keefe


    Playlist: Neutrinos from blazar TXS 0506+056


    Playlist: IceCube explained

    There are over 5,000 eyeballs buried in the ice at the South Pole. Not real eyeballs, but basketball-sized devices called digital optical modules (DOMs) that serve as the eyes of the IceCube Neutrino Observatory. Each DOM contains an instrument called a photomultiplier tube (PMT) that, like your eye, is able to register small amounts of light. Unlike your eye, these devices can register single photons that can be collected and sent to computers for processing.

    IceCube’s eyes are looking for signs that elusive, subatomic particles called neutrinos are passing through the ice. Specifically, IceCube pursues neutrinos that originate far out in the universe: astrophysical neutrinos. Sometimes, when an astrophysical neutrino passes through the detector, it interacts with matter near the detector and produces a cone of light called Čerenkov radiation. When a particle of that light—a photon—hits the surface of a DOM, its minute interaction can be amplified by the PMT into a signal that the electronics are able to register.

    Researchers in the IceCube Collaboration are always looking for ways to improve the understanding of the PMTs so they can get the highest-quality data from the DOMs. Most recently, they implemented a new method for more accurately characterizing individual PMT charge distributions, which was shown to improve PMT calibration and simulation. The method is described in a technical report, “In-situ calibration of the single-photoelectron charge response of the IceCube photomultipliers,” submitted recently to the Journal of Instrumentation.

    1
    The black histogram is an example charge distribution from DOM 1 string 1 (also known as “Mouse Trap”). A photon incident on the surface of the PMT would ideally be measured as generating one photoelectron (PE), which is why the horizontal axis is scaled such that the distribution peaks at this value, but other physical processes create shape in this distribution. Researchers can use the complete fit to this distribution (red) to extract the shape of what a pure sample of single photoelectrons would look like (blue). This blue shape describes the distribution of recorded signals generated from single photons. Credit: IceCube Collaboration.

    When a photon of Čerenkov light reaches a PMT inside a DOM, it will first encounter the photocathode, which in turn ejects an electron. That electron will be attracted to a charged plane (dynode) inside the PMT that then releases several new electrons. These electrons are attracted by the next dynode, which ejects even more electrons, and so on. This continues until an avalanche of electrons hits the final plane (anode). The pulse of charge generated by this avalanche is then digitized and the electrical output is sent up through a cable to the IceCube computing laboratory. The PMT’s ability to amplify the signal from photocathode to anode is known as its “gain.”

    Many factors make it difficult to determine the actual gain on an individual PMT, and using the wrong gain in simulations can cause problems. This has happened in previous IceCube analyses, leading to small but detectable disagreements between the simulation and the experimental data, especially in charge-related variables such as the average charge collected per PMT, per event. Since simulations are used to analyze IceCube data, it is important to find the accurate gain for PMTs.

    But no two PMTs are exactly the same. So researchers express the expected charge that a single photon generates in a given PMT as a probability curve, known as the single photoelectron (SPE) charge distribution. (Observed charge is often rescaled in units of photoelectrons.) The measured gain can also be used for evaluating the long-term stability of the detector and the accuracy of previous calibrations.

    One of the problems the researchers had to address was contamination in the signal. “A single photon produces a single electron at the photocathode,” explains Spencer Axani of the Massachusetts Institute of Technology, who led this analysis. “This electron then gets amplified, and the average resulting charge, about 107 electrons, is what we call an SPE. But the amplification is a statistical process, and there are a lot of physical processes that can lead to additional smearing of the amplified charge of an individual photon.”

    So Axani and his collaborators used a specially designed pulse selection software to remove some forms of contamination, allowing them to extract a sample of single photoelectrons from the data. They then used a newly developed fitting algorithm to create an SPE charge template per DOM.

    This extraction of SPE distributions allowed for an improved description of the detector in simulation and several interesting studies. For example, Axani and his collaborators inserted the SPE charge templates into simulation, which improved the data-simulation agreement in charge-related variables. This led to accurate determination of the gain setting and therefore allowed researchers to confirm that previous calibration had been done properly. The more accurate gain will also improve future calibration.

    They also used the measured distributions to search for changes in the fitted quantities (for example, what fractions of photons get properly or poorly amplified by the PMTs) over time. No changes were observed, which indicates that the calibration of the detector is properly accounting for the slow aging of the PMT.

    Lastly, researchers used the SPE charge template to investigate correlations between the measured charge distribution from each DOM and their corresponding hardware. The IceCube detector includes two sets of DOMs—high quantum efficiency and standard efficiency DOMs—and Axani and his collaborators found that the shape of the SPE charge templates for these two subsets are somewhat different. Now, their differences have been modeled.

    “Overall, we are pleased with the improvement that we saw in the agreement between the experimental data and the simulated data for charge-related variables,” says Martin Rongen of RWTH Aachen University, another lead on this analysis. He and Axani say their method can also be used to more accurately set the gain on the in-ice PMTs in future data-taking periods, thus improving the overall calibration of the detector.

    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 DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

     
  • richardmitnick 4:17 pm on January 31, 2020 Permalink | Reply
    Tags: , , Glashow resonance, In 2012 the IceCube collaboration reported the first observation of ultra-high energy neutrinos from extraterrestrial sources., Interactions beyond the standard model of particle physics., , , , The 'Zee burst' model, U Wisconsin IceCube and IceCube Gen-2, ,   

    From Washington University in St.Louis via phys.org: “Ultra-high energy events key to study of ghost particles” 

    Wash U Bloc

    From Washington University in St.Louis

    via


    phys.org

    January 31, 2020
    Talia Ogliore

    1
    Physicists in Arts & Sciences have proposed a new way to leverage data from large neutrino telescopes such as the IceCube Neutrino Observatory in Antarctica. Credit: Felipe Pedreros/IceCube and National Science Foundation

    Physicists at Washington University in St. Louis have proposed a way to use data from ultra-high energy neutrinos to study interactions beyond the standard model of particle physics. The ‘Zee burst’ model leverages new data from large neutrino telescopes such as the IceCube Neutrino Observatory in Antarctica and its future extensions.

    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 DeepCore annotated

    DM-Ice at IceCube

    “Neutrinos continue to intrigue us and stretch our imagination. These ‘ghost particles’ are the least understood in the standard model, but they hold the key to what lies beyond,” said Bhupal Dev, assistant professor of physics in Arts & Sciences and author of a new study in Physical Review Letters.

    “So far, all nonstandard interaction studies at IceCube have focused only on the low-energy atmospheric neutrino data,” said Dev, who is part of Washington University’s McDonnell Center for the Space Sciences. “The ‘Zee burst’ mechanism provides a new tool to probe nonstandard interactions using the ultra-high energy neutrinos at IceCube.”

    Ultra-high energy events

    Since the discovery of neutrino oscillations two decades ago, which earned the 2015 Nobel Prize in physics, scientists have made significant progress in understanding neutrino properties—but a lot of questions remain unanswered.

    For example, the fact that neutrinos have such a tiny mass already requires scientists to consider theories beyond the standard model. In such theories, “neutrinos could have new nonstandard interactions with matter as they propagate through it, which will crucially affect their future precision measurements,” Dev said.

    2
    This is the highest-energy neutrino ever observed, with an estimated energy of 1.14 PeV. It was detected by the IceCube Neutrino Observatory at the South Pole on Jan. 3, 2012. IceCube physicists named it Ernie. Credit: IceCube collaboration

    In 2012, the IceCube collaboration reported the first observation of ultra-high energy neutrinos from extraterrestrial sources, which opened a new window to study neutrino properties at the highest possible energies. Since that discovery, IceCube has reported about 100 such ultra-high energy neutrino events.

    “We immediately realized that this could give us a new way to look for exotic particles, like supersymmetric partners and heavy decaying dark matter,” Dev said. For the previous several years, he had been looking for ways to find signals of new physics at different energy scales and had co-authored half a dozen papers studying the possibilities.

    “The common strategy I followed in all these works was to look for anomalous features in the observed event spectrum, which could then be interpreted as a possible sign of new physics,” he said.

    The most spectacular feature would be a resonance: what physicists witness as a dramatic enhancement of events in a narrow energy window. Dev devoted his time to thinking about new scenarios that could give rise to such a resonance feature. That’s where the idea for the current work came from.

    In the standard model, ultra-high energy neutrinos can produce a W-boson at resonance. This process, known as the Glashow resonance, has already been seen at IceCube, according to preliminary results presented at the Neutrino 2018 conference.

    “We propose that similar resonance features can be induced due to new light, charged particles, which provides a new way to probe nonstandard neutrino interactions,” Dev said.

    3
    Rendering of an observation of the ultra-high energy events that feed into the ‘Zee burst’ model. Credit: Yicong Sui, Washington University

    Bursting onto the neutrino scene

    Dev and his co-author Kaladi Babu at Oklahoma State University considered the Zee model, a popular model of radiative neutrino mass generation, as a prototype for their study. This model allows for charged scalars to be as light as 100 times the proton mass.

    “These light, charged Zee-scalars could give rise to a Glashow-like resonance feature in the ultra-high energy neutrino event spectrum at the IceCube Neutrino Observatory,” Dev said.

    Because the new resonance involves charged scalars in the Zee model, they decided to call it the ‘Zee burst.’

    Yicong Sui at Washington University and Sudip Jana at Oklahoma State, both graduate students in physics and co-authors of this study, did extensive event simulations and data analysis showing that it is possible to detect such a new resonance using IceCube data.

    “We need an effective exposure time of at least four times the current exposure to be sensitive enough to detect the new resonance—so that would be about 30 years with the current IceCube design, but only three years of IceCube-Gen 2,” Dev said, referring to the proposed next-generation extension of IceCube with 10 km3 detector volume.

    “This is an effective way to look for the new charged scalars at IceCube, complementary to direct searches for these particles at the Large Hadron Collider.”

    See the full article here .

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    About Science X in 100 words

    Science X™ is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004 (Physorg.com), Science X’s readership has grown steadily to include 5 million scientists, researchers, and engineers every month. Science X publishes approximately 200 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Science X community members enjoy access to many personalized features such as social networking, a personal home page set-up, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.
    Mission 12 reasons for reading daily news on Science X Organization Key editors and writersinclude 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

    Wash U campus

    Washington University’s mission is to discover and disseminate knowledge, and protect the freedom of inquiry through research, teaching, and learning.

    Washington University creates an environment to encourage and support an ethos of wide-ranging exploration. Washington University’s faculty and staff strive to enhance the lives and livelihoods of students, the people of the greater St. Louis community, the country, and the world.

     
  • richardmitnick 8:33 am on January 18, 2020 Permalink | Reply
    Tags: "IceCube performs the first-ever search for neutrinos from the sun’s atmosphere", , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “IceCube performs the first-ever search for neutrinos from the sun’s atmosphere” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From U Wisconsin IceCube Collaboration

    17 Jan 2020
    Madeleine O’Keefe

    Neutrinos are lightweight, elusive, and abundant particles; trillions stream through your body every second. Many of these neutrinos are produced when cosmic rays (energetic particles from outer space) interact with nuclei in Earth’s atmosphere, triggering a shower of secondary particles, including neutrinos. Specifically, these are known as atmospheric neutrinos.

    But this process is not exclusive to Earth. The sun, the largest body in the solar system, also has an atmosphere. As cosmic rays propagate throughout space, they also enter the solar atmosphere and interact with nuclei there. Secondary showers in the solar atmosphere produce gamma rays and neutrinos that can be detected here on Earth. Recently, gamma rays from the sun were observed here by a space telescope, Fermi-LAT, but experimental studies have yet to show any neutrinos from solar cosmic ray interactions.

    The IceCube Collaboration recently performed the first-ever experimental search for these so-called “solar atmospheric neutrinos.” Such a detection would have important implications for understanding solar magnetic fields and how cosmic rays propagate in the inner solar system, and it could even provide additional background to solar dark matter searches. But after investigating seven years of IceCube data, IceCube researchers did not detect any solar atmospheric neutrinos and so set an upper limit on the flux. Their results are outlined in a paper that was recently submitted to the Journal of Cosmology and Astroparticle Physics.

    1
    A diagram showing neutrinos and gamma rays being generated in the solar atmosphere and flying toward IceCube and Fermi-LAT, respectively. (Not to scale.) Credit: Seongjin In, IceCube Collaboration

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    “One main difference between neutrinos produced in Earth’s atmosphere compared to the sun’s is the density of each atmosphere where the cosmic ray interactions occur,” says Seongjin In of Sungkyunkwan University in Seoul, South Korea, a lead on this analysis. Because of the different densities, we expect a greater flux for solar atmospheric neutrinos than Earth atmospheric neutrinos when looking at high-energy neutrinos—i.e., above 10^12 electronvolts (teravolt, or TeV) levels. Fortunately, IceCube is optimized to study these energy ranges.

    In and his collaborators investigated IceCube data collected between 2010 and 2017. “We tracked the sun in the sky and selected IceCube data within a circular window of five degrees in angular distance from the center of the sun,” he says. “We then calculated a score for the data that reflects whether it could be explained with the background prediction only.” In other words, if the distribution of neutrino energy and the angular distance differed from what they expected, it could indicate that some neutrinos were produced in the sun’s atmosphere.

    Ultimately, they found no evidence of solar atmospheric neutrinos; their observation was consistent with the background predictions. But In and his colleagues were able to set an upper limit on the solar atmospheric neutrino flux.

    3
    Limits for solar atmospheric neutrinos in IceCube (black dashed lines). Other points are the results of gamma-ray experiments. Credit: IceCube Collaboration

    Importantly, this is the first experimental search for solar atmospheric neutrinos and the first experimental bound on its flux. And it certainly won’t be the last. There is already another search being carried out at Sungkyunkwan University by one of In’s colleagues.

    After all, it’s possible that the researchers just weren’t looking at the right time. “If the neutrino flux modulates similarly to that of gamma rays, then the flux of solar atmospheric neutrinos may increase during the solar minimum,” says In, referring to the natural period of least solar activity in the sun’s 11-year cycle. “That means there might be a higher chance of observing solar atmospheric neutrino with data collected in the next solar minimum in 2020.”

    There is still much to find out about solar atmospheric neutrinos, and IceCube will continue to be part of the search.

    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 DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

     
  • richardmitnick 3:46 pm on January 9, 2020 Permalink | Reply
    Tags: , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From Symmetry: “Expanding a neutrino hunt in the South Pole” 

    Symmetry Mag
    From Symmetry<

    01/09/20
    Diana Kwon

    1
    Photo by Martin Wolf, IceCube/NSF

    A forthcoming upgrade to the IceCube detector will provide deeper insights into the elusive particles.

    Underneath the vast, frozen landscape of the South Pole lies IceCube, a gigantic observatory dedicated to finding ghostly subatomic particles called neutrinos. Neutrinos stream through the Earth from all directions, but they are lightweight, abundant and hardly interact with their surroundings.

    The IceCube detector consists of an array of 86 strings festooned with more than 5000 sensors, like round, basketball-sized Christmas lights. They reach more than 2 kilometers (more than 1 mile) down through layers of Antarctic ice that have accumulated over hundreds of thousands of years.

    A small fraction of the neutrinos that pass through the ice collide with its atoms and spit out showers of particles, some of which can be spotted by IceCube’s sensors as sparks of blue light. By probing the light patterns, scientists can identify and assess the elusive particles, some of which originate beyond our solar system.

    In July 2019 the IceCube collaboration announced that the US National Science Foundation had granted it $23 million to put toward a $37 million upgrade, with additional financial support coming from Michigan State University, the University of Wisconsin–Madison, and agencies in Germany and Japan.

    The upgrade will add seven more strings of sensors to the detector, along with new instruments meant to characterize the ice. This extension will allow physicists to better understand how neutrinos oscillate between their three flavors: electron, muon and tau. Scientists also plan to make more precise measurements of IceCube’s icy interior to get a closer look at neutrinos from far out in the universe.

    U Wisconsin IceCube neutrino observatory

    U Wisconsin ICECUBE neutrino detector at the South Pole

    U Wisconsin IceCube experiment at the South Pole



    U Wisconsin ICECUBE neutrino detector at the South Pole


    IceCube Gen-2 DeepCore PINGU


    IceCube reveals interesting high-energy neutrino events

    3
    When cosmic neutrinos crash into the IceCube detector, the interactions generate secondary particles that travel faster than the speed of light through the ice, producing a detectable faint blue glow. Courtesy of Nicolle R. Fuller/NSF/IceCube

    Extraterrestrial signals

    One of the main aims of IceCube, which is run by an international group of more than 300 scientists from 12 different countries, is to identify cosmic neutrinos. They know which neutrinos come from afar by the extraordinarily high levels of energy they have when they crash into the Earth, compared to their more local counterparts. By studying these alien particles, physicists hope to identify the powerful cosmic accelerators that form beams of ultra-high energy particles.

    IceCube had its first major breakthrough in 2013 when it identified two ultra-high energy neutrinos from outside the solar system. These events, dubbed Bert and Ernie, became the first of many cosmic neutrino detections, says Olga Botner, a physicist at Uppsala University in Sweden and former spokesperson of IceCube.

    “We knew we were in business,” she says. “We could observe not only the atmosphere but also neutrinos from outside our own galaxy. That was huge.”

    Four years later, IceCube physicists made a detection of an extraterrestrial neutrino that sparked a search for a glimpse of its source by scientists at astronomical observatories around the globe. This worldwide hunt allowed scientists to pinpoint the particle’s birthplace: an extremely luminous galaxy called a blazar. A blazar acts like a cosmic accelerator, spitting out a constant stream of particles from its core.

    “Working on IceCube is very exciting,” says Delia Tosi, an assistant scientist at the Wisconsin IceCube Particle Astrophysics Center (WIPAC). “There is no space for boredom.”

    Where most cosmic neutrinos come from remains a mystery. But IceCube’s scientific repertoire has expanded since those first discoveries. Scientists also use IceCube to examine how neutrinos change from one type to another—which could help determine whether there are new types of neutrinos that we don’t yet know about—as well as to search for dark matter and characterize how light travels though Antarctic ice.

    “When we started IceCube, we were 90% focused on finding point sources of astrophysical neutrinos,” says Kael Hanson, a physicist and director of WIPAC. “We really had no idea, when we were designing the experiment, how rich the science program would eventually become.”

    An upgrade on ice

    With the forthcoming upgrade, more than 700 new sensors spread across seven strings will be added to the center of IceCube.

    The core is already more densely packed with strings than the rest of the detector, which makes it better able to detect particles at low energies. The new sensors will push that sensitivity even further. “We’re pushing the energy threshold down by a factor of 10,” Hanson says.

    The denser core will make it possible for the scientists to examine the hundreds of thousands of atmospheric neutrinos that bombard the detector each year in more detail. This will allow physicists to make more accurate measurements of the tau neutrino, which can then be used to better understand neutrino oscillations—specifically, how muon neutrinos convert to tau neutrinos.

    “We don’t quite understand how neutrinos can spontaneously morph from one flavor to another,” Botner says. “If discrepancies exist between our predictions and what we observe, this would be a hint of unknown neutrino kinds—the so-called sterile neutrino.”

    To insert new strings into the detector, scientists must drill deep holes into the ice using a high-pressure stream of hot water. During the upgrade, scientists will deploy additional calibration instruments, such as cameras and light sources, along with the detectors to help them characterize the ice.

    When water refreezes around the strings—a process that can take several weeks—the ice that forms can contain dust and bubbles. These imperfections make it more difficult to see signs of neutrinos.

    Not only will characterizing the ice make it possible for scientists to more accurately assess future observations, researchers will also be able to apply this new knowledge to previously collected data. “In principle, we can recalibrate all the data and improve our ability to point back to a source,” says Dawn Williams, a particle astrophysicist at the University of Alabama.

    The IceCube collaboration plans to start drilling in late 2022. In the meantime, the group is preparing the sensors and other components of the upgrade as well as the software that will be used to run the upgraded detector. The team expects to start collecting data in the spring of 2023.

    The upgrade also serves an additional purpose: to test new sensor designs that scientists hope might be deployed in IceCube-Gen2, a proposed detector that would be 10 times the size of the current one. The super-sized observatory would allow scientists to conduct even more precise measurements of neutrinos and detect more ultra-high-energy particles from outer space, heightening the possibly of pinpointing their sources.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:42 am on November 14, 2019 Permalink | Reply
    Tags: "What can cascade events tell us about neutrino sources?", , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “What can cascade events tell us about neutrino sources?” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    13 Nov 2019
    Madeleine O’Keefe

    On a dark, clear night, you can look up and see the Milky Way galaxy: billions of stars shining in visible light. But we also expect our galaxy to “shine” in neutrinos, elusive particles whose origins are still mysterious. There are cosmic-ray sources within our galaxy, so these sources must also produce neutrinos.

    Cosmic rays produced by high-energy astrophysics sources (ASPERA collaboration – AStroParticle ERAnet)

    We cannot see neutrinos with our eyes, but the IceCube Neutrino Observatory can detect them. IceCube “sees” with 5,160 optical sensors buried deep in glacial ice at the South Pole.

    When neutrinos pass through IceCube, they will sometimes leave signals, known as “events,” primarily as either tracks or cascades. The former occur when a neutrino collides with matter in or near IceCube, resulting in a high-energy muon that travels a long distance, leaving an elongated “track” of signals in its wake. Cascades happen when all or most of the neutrino’s energy is deposited in a small region and results in a nearly spherical event, making it hard to measure the direction from which the parent neutrino came.

    Cascades are more difficult to reconstruct than tracks, which are usually used in searches for astrophysical neutrino sources, but they have their own advantages, including providing a better measurement of neutrino energy. By studying cascade events, researchers enhance IceCube’s sensitivity to possible neutrino sources in the southern sky, including the Galactic Center.

    In a paper published today in The Astrophysical Journal, the IceCube Collaboration outlined recent results from a source search that used seven years of data from cascade events. While they did not find any statistically significant sources of neutrino emissions, this work is an improvement on the previous source search with cascades.

    1
    Results from the all-sky scan for neutrino point sources, with the center and plane of the Milky Way shown by the grey dot and curve, respectively. No statistically significant emission was identified. Credit: IceCube Collaboration

    Cascades have the advantage that atmospheric backgrounds are small and relatively uniform throughout the sky. IceCube collaborators previously used two years of cascades in a similar analysis. The current work is an improvement on that analysis in three ways: the use of seven years of data, greatly improved directional reconstruction, and the added emphasis on testing for possible sources within the Milky Way.

    To perform their analysis, IceCube scientists first improved the directional reconstruction by using a deep convolutional neural network inspired by recent work in image recognition, rather than the traditional statistical approach. “In principle, the traditional approach should perform better,” says Mike Richman, a postdoctoral researcher at Drexel University and the lead on the analysis, “but in practice, our model of the glacial ice is sufficiently complex that it’s difficult to guarantee that method converges on the optimal result.”

    Richman credits fellow IceCube collaborator Mirco Huennefeld of Universität Dortmund for his extensive work on the angular reconstruction used in the analysis. “Mirco has trained a model with an implicit understanding of the detector and the ice, and it’s able to obtain good results without resorting to expensive numerical scans.”

    Armed with this improved reconstruction applied to seven years of data, the researchers performed two types of analysis: searches for point sources and searches for broad emission regions in our galaxy. The point source searches included a scan of the whole sky, a scan over 74 preselected potential sources, and a test for sum-total emission from three short lists of interesting supernova remnants. The broad emission regions included gas and dust distributed throughout the Milky Way and the giant “Fermi bubbles” near the center of our galaxy. Many of these tests were the most sensitive performed to date by any experiment.

    Ultimately, the researchers did not find evidence for neutrino emission. However, they did acknowledge an interesting trend: As the Milky Way measurements become more sensitive (from using just IceCube tracks, to IceCube tracks and ANTARES events [The Astrophysical Journal Letters], and now to just IceCube cascades), the result becomes increasingly significant. Furthermore, the galactic neutrino energy spectrum suggested by the cascade data agrees with previous IceCube work with tracks. While not conclusive, this is consistent with emission that is just below the sensitivity of analyses done so far.

    This work solidifies the importance of using all neutrino flavors to search for sources—at least with current-generation detectors. Going forward, Richman says they plan to improve the cascade analysis by applying the latest reconstructions to data collected over more time and extending to even lower energies (below 1 TeV). They expect data from the IceCube Upgrade to reduce systematic uncertainties, leading to still better sensitivity.

    In the future, the plan is to study additional source types, including ones with time-dependent—and potentially very short-lived—emission. They also plan to combine IceCube tracks and cascades and ultimately to perform a “global” analysis that includes all event types from all available data.

    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 DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

     
  • richardmitnick 8:41 am on October 22, 2019 Permalink | Reply
    Tags: "New all-sky search reveals potential neutrino sources", , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “New all-sky search reveals potential neutrino sources” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    21 Oct 2019
    Madeleine O’Keefe

    For over a century, scientists have been observing very high energy charged particles called cosmic rays arriving from outside Earth’s atmosphere. The origins of these particles are very difficult to pinpoint because the particles themselves do not travel on a straight path to Earth. Even gamma rays, a type of high-energy photon that offers a little more insight, are absorbed when traversing long distances.

    The IceCube Neutrino Observatory, an array of optical modules buried in a cubic kilometer of ice at the South Pole, hunts for cosmic-ray sources inside and outside our galaxy—extending to galaxies more than billions of light years away—using hints from elusive particles called neutrinos. These neutrinos are expected to be produced by cosmic-ray collisions with gas or radiation near the sources.

    Unlike cosmic rays, neutrinos are not absorbed or diverted on their way to Earth, making them a practical tool for locating and understanding cosmic accelerators. If scientists can find a source of high-energy astrophysical neutrinos, this would be a smoking gun for a cosmic-ray source.

    After 10 years of searching for origins of astrophysical neutrinos, a new all-sky search provides the most sensitive probe of time-integrated neutrino emission of point-like sources. The IceCube Collaboration presents the results of this scan in a paper submitted recently to Physical Review Letters.

    1
    The pre-trial probability of the observed signal being due to background in a 5×5 degree window around the most significant point in the Northern Hemisphere (the hottest spot); the black cross marks the Fermi-3FGL coordinates of the galaxy NGC 1068. Credit: IceCube Collaboration

    Tessa Carver led this analysis under the supervision of Teresa Montaruli in the Département de Physique Nucléaire et Corpusculaire at the University of Geneva in Switzerland. “IceCube has already observed an astrophysical flux of neutrinos, so we know they exist and are detectable—we just don’t know exactly where they come from,” says Carver, now a postdoc at Cardiff University. “It is only a matter of time and precision until we can identify the sources behind this neutrino flux.”

    The principle challenge in searching for astrophysical neutrino sources with IceCube is the overwhelming background of events induced by cosmic-ray interactions in our atmosphere. The signal of faint neutrino sources needs to be extracted via sophisticated statistical analysis techniques.

    Using these methods, Carver and her collaborators “scanned” across the entire sky to look for point-like neutrino sources at arbitrary locations. This scanning method is able to identify very bright neutrino sources that could be invisible in gamma rays, which are also produced in cosmic-ray collisions.

    In order to be sensitive to dimmer sources, they also analyzed 110 galactic and extragalactic source candidates, which have been observed via gamma rays. They then combined the results obtained for individual sources in this list in a “population analysis,” which looks for a higher-than-expected rate of significant results from the individual source list search. This allows researchers to find significant neutrino emission, even if sources in the list are too weak to be observed individually.

    Researchers also employed a “stacking search” for three catalogs of gamma-ray sources within our galaxy. This search layers together all the emission from groups of known objects of the same type under the assumption that they have well-known emission properties. While it can significantly reduce the per-source emission required to observe a large excess of signal over the background, this search is limited in that it requires more knowledge of the sources in the catalog.

    2
    Skymap of -log10(plocal), where plocal is the local pre-trial p-value, for the area between ±82 degrees declination in equatorial coordinates. The Northern and Southern Hemisphere hotspots, defined as the most significant plocal in the given hemisphere, are indicated with black circles. Credit: IceCube Collaboration

    While the different analyses did not discover steady neutrino sources, the results are nevertheless exciting: some of the objects in the catalog of known sources showed a higher neutrino flux than expected, with excesses at the 3σ-level. In particular, the all-sky scan revealed that the “hottest” location in the sky is just 0.35 degrees away from the starburst galaxy NGC 1068, which has a 2.9σ excess over background. NGC 1068 is one of the closest black holes to us; it is embedded in a star-forming region with lots of matter for neutrinos to interact with while the high-energy gamma rays are attenuated, as shown by Fermi and MAGIC measurements.

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    MAGIC Čerenkov telescopes at the Observatorio del Roque de los Muchachos (Garfia, La Palma, Spain)), Altitude 2,396 m (7,861 ft)

    This is the most significant excess seen besides TXS 0506-056, the 2017 source that IceCube found to be coincident with a gamma ray flare. Still, these potential neutrino sources require more data with a more-sensitive detector, like IceCube-Gen2, to be confirmed.

    The researchers also found that the Northern Hemisphere source catalog as a whole differed from background expectations with a significance of 3.3σ. Carver says these results demonstrate a strong motivation to continue to analyze the objects in the catalog. Time-dependent analyses, which search for flares of peaked emission, and the possibility of correlating neutrino emission with electromagnetic or gravitational wave observations for these and other sources may provide additional evidence of neutrino emission and insights into the neutrinos’ origin. With continued data-taking, more refined direction reconstruction, and the upcoming IceCube Upgrade, further improvements in sensitivity are on the horizon.

    “We are lucky to have the unique opportunity to be the first people to map the universe with neutrinos, which provides a brand-new perspective,” says Carver. “Also, this progress in neutrino astronomy is accompanied by great strides in gravitational wave physics and cosmic-ray physics.”

    Montaruli adds, “While we are at the dawn of a new era in astronomy that observes the universe not just with light, this is the first time we have begun to see potentially significant excesses of candidate neutrino events around interesting extragalactic objects in time-independent searches.”

    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 DeepCore annotated

    IceCube PINGU annotated


    DM-Ice II at IceCube annotated

     
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