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  • 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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    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 .

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

    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 .

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

    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 2:46 pm on October 2, 2019 Permalink | Reply
    Tags: , , The neutrino event IceCube 170922A and the distant BL Lac object active galaxy TXS 0506+056, This was the first neutrino from outer space whose origin could be confirmed., U Wisconsin IceCube and IceCube Gen-2   

    From Max Planck Institute for Radio Astronomy: “Neutrino produced in a cosmic collider far away” 


    From Max Planck Institute for Radio Astronomy

    October 02, 2019

    Priv.-Doz. Dr. Silke Britzen
    Phone:+49 228 525-280
    sbritzen@mpifr-bonn.mpg.de
    Max Planck Institute for Radio Astronomy,Bonn

    Prof. Dr. Christian Fendt
    Phone:+49 6221 528-387
    fendt@mpia-hd.mpg.de.
    Max Planck Institute for Radio Astronomy,Heidelberg

    Max-Planck-Institut für Astronomie,
    Dr. Norbert Junkes
    Press and Public Outreach
    Phone:+49 228 525-399
    njunkes@mpifr-bonn.mpg.de
    Max Planck Institute for Radio Astronomy,Bonn

    Link between IceCube neutrino event and distant radio galaxy resolved

    The neutrino event IceCube 170922A, detected at the IceCube Neutrino Observatory at the South Pole, appears to originate from the distant active galaxy TXS 0506+056, at a light travel distance of 3.8 billion light years. TXS 0506+056 is one of many active galaxies and it remained a mystery, why and how only this particular galaxy generated neutrinos so far.

    An international team of researchers led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, studied high-resolution radio observations of the source between 2009 and 2018, before and after the neutrino event. The team proposes that the enhanced neutrino activity during an earlier neutrino flare and the single neutrino could have been generated by a cosmic collision within TXS 0506+056. The clash of jet material close to a supermassive black hole seems to have produced the neutrinos.

    The results are published in Astronomy & Astrophysics, October 02, 2019.

    1
    TXS 0506+056. The neutrino event IceCube 170922A appears to originate in the interaction zone of the two jets.
    © IceCube Collaboration, MOJAVE, S. Britzen, & M. Zajaček

    On July 12, 2018, the IceCube collaboration announced the detection of the first high-energy neutrino, IceCube-170922A, which could be traced back to a distant cosmic origin. While the cosmic origin of neutrinos had been suspected for quite some time, this was the first neutrino from outer space whose origin could be confirmed. The “home” of this neutrino is an Active Galactic Nucleus (AGN) – a galaxy with a supermassive black hole as central engine. An international team could now clarify the production mechanism of the neutrino and found an equivalent to a collider on Earth: a cosmic collision of jetted material.

    AGN are the most energetic objects in our Universe. Powered by a supermassive black hole, matter is being accreted and streams of plasma (so-called jets) are launched into intergalactic space. BL Lac objects form a special class of these AGN, where the jet is directly pointing at us and dominating the observed radiation. The neutrino event IceCube-170922A appears to originate from the BL Lac object TXS 0506+056, a galaxy at a redshift of z=0.34, corresponding to a light travel distance of 3.8 billion light years. An analysis of archival IceCube data by the IceCube Collaboration had revealed evidence of an enhanced neutrino acitvity earlier, between September 2014 and March 2015.

    Other BL Lac Objects show properties quite similar to those of TXS 0506+056. „It was a bit of a mystery, however, why only TXS 0506+056 has been identified as neutrino emitter“, explains Silke Britzen from the Max Planck Institute for Radio Astronomy (MPIfR), the lead author of the paper. „We wanted to unravel what makes TXS 0506+056 special, to understand the neutrino creation process and to localize the emission site and studied a series of high resolution radio images of the jet.“

    Much to their surprise, the researchers found an unexpected interaction between jet material in TXS 0506+056. While jet plasma is usually assumed to flow undisturbed in a kind of channel, the situation seems different in TXS 0506+056. The team proposes that the enhanced neutrino activity during the neutrino flare in 2014–2015 and the single EHE neutrino
    IceCube-170922A could have been generated by a cosmic collision within the source.

    This cosmic collision can be explained by new jet material clashing into older jet material. A strongly curved jet structure provides the proper set up for such a scenario. Another explanation involves the collision of two jets in the same source. In both scenarios, it is the collision of jetted material which generates the neutrino. Markus Böttcher from the North-West University in Potchefstroom (South Africa), a co-author of the paper, performed the calculations with regard to the radiation and particle emission. „This collision of jetted material is currently the only viable mechanism which can explain the neutrino detection from this source. It also provides us with important insight into the jet material and solves a long-standing question whether jets are leptonic, consisting of electrons and positrons, or hadronic, consisting of electrons and protons, or a combination of both. At least part of the jet material has to be hadronic – otherwise, we would not have detected the neutrino.“

    In the course of the cosmic evolution of our Universe, collisions of galaxies seem to be a frequent phenomenon. Assuming that both galaxies contain central supermassive black holes, the galactic collision can result in a black hole pair at the centre. This black hole pair might eventually merge and produce the supermassive equivalent to stellar black hole mergers as detected in gravitational waves by the LIGO/Virgo collaboration.

    AGN with double black holes at a small separation of only light years have been pursued for many years. However, they seem to be rare and difficult to identify. In addition to the collision of jetted material, the team also found evidence for a precession of the central jet of TXS 0506+056. According to Michal Zajaček from the Center for Theoretical Physics, Warsaw: „This precession can in general be explained by the presence of a supermassive black hole binary or the Lense-Thirring precession effect as predicted by Einstein’s theory of general relativity. The latter could also be triggered by a second, more distant black hole in the centre. Both scenarios lead to a wandering of the jet direction, which we observe.“

    Christian Fendt from the Max Planck Institute for Astronomy in Heidelberg is amazed: „The closer we look at the jet sources the more complicated the internal structure and jet dynamics appears. While binary black holes produce a more complex outflow structure, their existence is naturally expected from the cosmological models of galaxy formation by galaxy mergers.”

    Silke Britzen stresses the scientific potential of the findings: „It’s fantastic to understand the neutrino generation by studying the insides of jets. And it would be a breakthrough if our analysis had provided another candidate for a binary black hole jet source with two jets.“

    It seems to be the first time that a potential collision of two jets on scales of a few light years has been reported and that the detection of a cosmic neutrino might be traced back to a cosmic jet-collision.

    While TXS 0506+056 might not be representative of the class of BL Lac objects, this source could provide the proper setup for a repeated interaction of jetted material and the generation of neutrinos.

    ——————————-
    Background Information:

    U Wisconsin ICECUBE neutrino detector at the South Pole

    The IceCube Neutrino Observatory is designed to observe the cosmos from deep within the South Pole ice.

    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

    Encompassing a cubic kilometer of ice, IceCube searches for nearly massless subatomic particles called neutrinos. These high-energy astronomical messengers provide information to probe the most violent astrophysical sources: events like exploding stars, gamma-ray bursts, and cataclysmic phenomena involving black holes and neutron stars.

    MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) is a long-term program to monitor radio brightness and polarization variations in jets associated with active galaxies visible in the northern sky. The Very Long Baseline Array (VLBA) is a system of ten radio telescopes which are operated from Socorro, New Mexico. The ten radio antennas work together as an array using very long baseline interferometry.

    NRAO/VLBA

    A BL Lac Object is a special subclass of an Active Galactic Nucleus (AGN). An AGN is a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion of the electromagnetic spectrum. This luminosity is non-thermal and produced by accretion of matter close to a central black hole. The jet of a BL Lac Object is directed at the observer giving a unique radio emission spectrum.

    Authors of the original paper in “Astronomy & Astrophysics” are Silke Britzen, Christian Fendt, Markus Böttcher, Michal Zajaček, Frederic Jaron, Ilya Pashchenko, Anabella Araudo, Vladimir Karas, and Omar Kurtanidze. Silke Britzen, the first author, and also Michal Zajaček and Frederic Jaron are affiliated to the MPIfR.

    Besides MPIfR, affiliations of the authors include the Max-Planck-Institut für Astronomie (Heidelberg, Germany), the Centre for Space Research (North-West University, Potchefstroom, South Africa), the I. Physikalisches Institut, (Universität Köln, Germany), the Center for Theoretical Physics, (Polish Academy of Sciences, Warsaw, Poland), the Institute of Geodesy and Geoinformation (University of Bonn, Germany), the Astro Space Center, (Lebedev Physical Institute, Russian Academy of Sciences, Russia), the Astronomical Institute and the Institute of Physics (Czech Academy of Sciences, Prague, Czech Republic) and the Abastumani Observatory in Georgia.

    See the full article here .

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    MPIFR/Effelsberg Radio Telescope, Germany

    The Max Planck Institute for Radio Astronomy (German: Max-Planck-Institut für Radioastronomie) is located in Bonn, Germany. It is one of 80 institutes in the Max Planck Society (German: Max-Planck-Gesellschaft).

    By combining the already existing radio astronomy faculty of the University of Bonn led by Otto Hachenberg with the new Max Planck institute the Max Planck Institute for Radio Astronomy was formed. In 1972 the 100-m radio telescope in Effelsberg was opened. The institute building was enlarged in 1983 and 2002.

    The institute was founded in 1966 by the Max-Planck-Gesellschaft as the “Max-Planck-Institut für Radioastronomie” (MPIfR).

    The foundation of the institute was closely linked to plans in the German astronomical community to construct a competitive large radio telescope in (then) West Germany. In 1964, Professors Friedrich Becker, Wolfgang Priester and Otto Hachenberg of the Astronomische Institute der Universität Bonn submitted a proposal to the Stiftung Volkswagenwerk for the construction of a large fully steerable radio telescope.

    In the same year the Stiftung Volkswagenwerk approved the funding of the telescope project but with the condition that an organization should be found, which would guarantee the operations. It was clear that the operation of such a large instrument was well beyond the possibilities of a single university institute.

    Already in 1965 the Max-Planck-Gesellschaft (MPG) decided in principle to found the Max-Planck-Institut für Radioastronomie. Eventually, after a series of discussions, the institute was officially founded in 1966.

    The Max Planck Society for the Advancement of Science (German: Max-Planck-Gesellschaft zur Förderung der Wissenschaften e. V.; abbreviated MPG) is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the Max Planck Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

    According to its primary goal, the Max Planck Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014)[2] Max Planck Institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

    The Max Planck Institutes focus on excellence in research. The Max Planck Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the Max Planck institutes fifth worldwide in terms of research published in Nature journals (after Harvard, MIT, Stanford and the US NIH). In terms of total research volume (unweighted by citations or impact), the Max Planck Society is only outranked by the Chinese Academy of Sciences, the Russian Academy of Sciences and Harvard University. The Thomson Reuters-Science Watch website placed the Max Planck Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

     
  • richardmitnick 4:22 pm on September 20, 2019 Permalink | Reply
    Tags: "Testing a new technique to search for neutrino point-source populations", , , , , , NPTF-non-Poissonian template fit, U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “Testing a new technique to search for neutrino point-source populations” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    20 Sep 2019
    Madeleine O’Keefe

    Neutrinos are one of the best sources of information about extreme-energy astrophysical phenomena at the far reaches of the observable universe. These intergalactic messengers are able to travel through space unaffected by magnetic fields or other forces. This means that, in theory, if we can measure a neutrino’s incident direction accurately enough, we could trace it back to its source and identify what produced it.

    When a number of neutrinos are associated with a single object in the sky, that object is called a “point source.” The IceCube Neutrino Observatory—an array of 5,160 optical modules embedded in a cubic kilometer of South Pole ice—has already performed a number of point source searches but has yet to identify any significant clustering of neutrinos that would be indicative of a single bright source. This might indicate that most of the neutrinos IceCube detects are not originating from a small number of bright sources, but instead a larger population of dim sources.

    The IceCube Collaboration performed a search for these populations using a technique called the non-Poissonian template fit (NPTF) and published their findings in a paper being submitted to The Astrophysical Journal. This was the first time the NPTF was used on IceCube neutrino data, and while they did not find any neutrino point-source populations, they proved the technique’s viability.

    1
    Left: A simulated image of a purely diffuse emission, where the fluctuations are only due to Poisson noise. Right: A simulated image of emission from a population of point sources. Note the larger fluctuations for the point sources (exaggerated to make the effect more easily discernible); this effect is what was used to determine the presence and properties of a population of point sources. Credit: IceCube Collaboration.

    The NPTF technique has a number of advantages over traditional point source search techniques, and it has been used widely with gamma-ray data. But this was the first time it was used for IceCube neutrino data.

    “We wanted to see whether a totally different approach to searching for point sources, based purely on the modification to the statistics of the basic count map, could be a viable technique to apply to the IceCube dataset,” says Nicholas Rodd of the University of California, Berkeley, one of the leads on this analysis.

    “When we take images of the sky, whether they are taken with cameras or neutrino telescopes, there is a certain amount of ‘graininess’ that is due to natural statistical fluctuations, which is called Poisson noise,” explains Institute for Data, Systems and Society postdoctoral associate Gabriel Collin, another lead author on this paper.

    The math behind Poisson noise assumes that the neutrinos are produced by one large continuous physical process, resulting in a “diffuse emission.” However, if the neutrinos are instead being produced by compact astronomical objects—which is what Rodd and Collin expect—then the graininess is enhanced, leading to fluctuations larger than the Poisson model predicts. The presence of these non-Poissonian fluctuations can indicate how many point sources are producing the neutrinos and how bright or dim they are.

    In this analysis, Rodd and Collin used the NPTF, which predicts the size of the fluctuations for a given theoretical model of the population of neutrino-producing astronomical objects. This formulation can detect the presence of a population of point sources even when the effect is slight, beyond what the human eye can discern.

    They ran IceCube neutrino data through their formulation, but did not find evidence of a population of point sources. This null result rules out certain theoretical models of these populations, and the analysis ultimately demonstrated that the NPTF could successfully be applied to the IceCube dataset.

    2
    This figure shows that, for a population of sources with a given intrinsic brightness (x-axis) and density throughout the universe (y-axis), the NPTF excludes populations in the white space. Such null observations still have important implications, including allowing researchers to quantify how much objects like galaxy clusters are dimmer in neutrinos than photons (here, photon brightness is depicted by “x”). Credit: IceCube Collaboration.

    The NPTF can perform a number of searches that are difficult with other techniques, such as searching for populations of sources that are not distributed uniformly in all orientations on the sky. And although the NPTF is currently less sensitive than other techniques in some parts of the parameter space, there are many options to extend the method’s reach and significantly enhance its sensitivity.

    “The goal of our analysis was to lay the groundwork for future work that leverages advanced statistical tools such as this non-Poissonian fluctuation model,” says Collin. “We hope that, through this effort, we can build a better bridge between the theoretical and experimental community in neutrino astronomy, and encourage future point-source population searches to publish their results in a similar fashion.”

    Looking toward the future, Collin says he and Rodd hope to develop even more powerful statistical tools that can be used to search for point-source populations—not just in neutrino astronomy, but in gamma-ray, X-ray, and optical astronomy as well.

    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 3:28 pm on September 6, 2019 Permalink | Reply
    Tags: , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “How to deal with “dust” in the Antarctic ice” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    06 Sep 2019
    Madeleine O’Keefe

    Even in Antarctica, scientists have to deal with a little dust in their detectors.

    The IceCube Neutrino Observatory is an array of over 5,000 optical sensors embedded in a cubic kilometer of ice at the South Pole. Ice has ideal properties for detecting neutrinos, so IceCube physicists took advantage of Antarctica’s abundant supply to construct their state-of-the-art neutrino observatory.

    But this comes with its own set of challenges. Most particle physics experiments are built with materials that can be characterized in the lab before installation. Meanwhile, the naturally occurring ice in which IceCube is embedded has impurities that reflect the climate history and atmospheric composition of the Earth. These impurities—all of which are referred to as “dust,” even though mineral dust is only one major component—affect how light travels through the IceCube detector and thus how the neutrino interactions appear.

    In a technical paper submitted to the Journal of Cosmology and Astroparticle Physics earlier this week, the IceCube Collaboration presents a new method to understand the optical properties of the ice, called the SnowStorm method. More specifically, the paper explores how SnowStorm might affect high-precision analyses, including upcoming sterile neutrino results.

    1
    Parameters used to formulate the ice model that is used by the SnowStorm approach. Each wave represents a part of the ice model that will be varied to understand the uncertainty in IceCube physics analyses. Credit: IceCube Collaboration

    As IceCube collects more data, it can produce increasingly precise measurements of the behavior of neutrinos. In order to make these measurements, though, it is mandatory that researchers gain a better understanding of the way the detector responds. Some of the major uncertainties in the high-precision study of neutrinos in IceCube involve understanding the properties of the glacial ice at the South Pole.

    One large source of systematic uncertainty is dust distribution in IceCube. This is because the effective dust concentration as a function of depth is difficult to estimate; it would require simulations for neutrino events in every reasonable ice model configuration, which is at present computationally unfeasible. In addition, the dust concentration varies continuously as a function of depth, and the uncertainty on this continuous function needs to be constrained and propagated without introducing an overwhelming number of nuisance parameters.

    So IceCube collaborators, led by University of Texas at Arlington (UTA) assistant professor of physics Ben Jones, developed SnowStorm, a fundamentally new way of simulating the IceCube experiment. Unlike the conventional Monte Carlo simulations, where scientists simulate events with different neutrino energies and angles, Jones and his collaborators randomized the detector’s optical properties in every simulated event. They then developed a mathematical framework to use those events to understand how they would affect measurements of neutrino properties.

    “This is a new technique for particle physics experiments, with applicability beyond IceCube, and so we decided to publish it so that other experimental physics collaborations can put its power to use,” says Jones.

    The SnowStorm method satisfied all the checks to which it was subjected. It has been adopted as the ice uncertainty model for the upcoming search for sterile neutrinos, in which hundreds of thousands of detected neutrinos will be used to test for the existence of hypothetical new neutrinos that have been suggested by other experiments, like the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE.

    The IceCube group at UTA is now working to extend the use of these powerful techniques to other analyses in IceCube, including the high-energy astrophysical neutrino measurements. They also hope to extend their applicability to other sources of systematic uncertainty, such as detector efficiencies and neutrino flux properties.

    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 4:25 pm on July 16, 2019 Permalink | Reply
    Tags: , , Michigan State University, , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: A Flock of Articles on NSF Grant to Upgrade IceCube 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    From U Wisconsin: “UW lab gears up for another Antarctic drilling campaign”

    With news that the National Science Foundation (NSF) and international partners will support an upgrade to the IceCube neutrino detector at the South Pole, the UW–Madison lab that built the novel drill used to bore mile-deep holes in the Antarctic ice is gearing up for another drilling campaign.

    The UW’s Physical Sciences Laboratory (PSL), which specializes in making customized equipment for UW–Madison researchers, will once again lead drilling operations. The $37 million upgrade announced this week (July 16, 2019) will expand the IceCube detector by adding seven new strings of 108 optical modules each to study the basic properties of neutrinos, phantom-like particles that emanate from black holes and exploding stars, but that also cascade through Earth’s atmosphere as a result of colliding subatomic particles.

    1
    “It takes a crew of 30 people to run this 24/7. It’s the people that make it work,” says Bob Paulos, director of the Physical Sciences Lab. Photo: Bryce Richter

    See the full article here .

    From U Wisconsin: “IceCube: Antarctic neutrino detector to get $37 million upgrade”

    2
    The IceCube Neutrino Observatory is located at NSF’s Amundsen-Scott South Pole Station. Management and operation of the observatory is through the Wisconsin IceCube Particle Astrophysics Center at UW–Madison. Raffaela Busse, IceCube / NSF

    IceCube, the Antarctic neutrino detector that in July of 2018 helped unravel one of the oldest riddles in physics and astronomy — the origin of high-energy neutrinos and cosmic rays — is getting an upgrade.

    This month, the National Science Foundation (NSF) approved $23 million in funding to expand the detector and its scientific capabilities. Seven new strings of optical modules will be added to the 86 existing strings, adding more than 700 new, enhanced optical modules to the 5,160 sensors already embedded in the ice beneath the geographic South Pole.

    The upgrade, to be installed during the 2022–23 polar season, will receive additional support from international partners in Japan and Germany as well as from Michigan State University and the University of Wisconsin–Madison. Total new investment in the detector will be about $37 million.

    See the full article here .

    From Niels Bohr Institute: “A new Upgrade for the IceCube detector”

    3
    Illustration of the IceCube laboratory under the South Pole. The sensors detecting neutrinos are attached to the strings lowered into the ice. The upgrade will take place in the Deep Core area. Illustration: IceCube/NSF

    Neutrino Research:

    The IceCube Neutrino Observatory in Antarctica is about to get a significant upgrade. This huge detector consists of 5,160 sensors embedded in a 1x1x1 km volume of glacial ice deep beneath the geographic South Pole. The purpose of the installation is to detect neutrinos, the “ghost particles” of the Universe. The IceCube Upgrade will add more than 700 new and enhanced optical sensors in the deepest, purest ice, greatly improving the observatory’s ability to measure low-energy neutrinos produced in the Earth’s atmosphere. The research in neutrinos at the Niels Bohr Institute, University of Copenhagen is led by Associate Professor Jason Koskinen

    See the full article here .

    From Michigan State University: “Upgrade for neutrino detector, thanks to NSF grant”

    5
    The IceCube Neutrino Observatory, the Antarctic detector that identified the first likely source of high-energy neutrinos and cosmic rays, is getting an upgrade. Courtesy of IceCube

    The IceCube Neutrino Observatory, the Antarctic detector that identified the first likely source of high-energy neutrinos and cosmic rays, is getting an upgrade.

    The National Science Foundation is upgrading the IceCube detector, extending its scientific capabilities to lower energies, and bridging IceCube to smaller neutrino detectors worldwide. The upgrade will insert seven strings of optical modules at the bottom center of the 86 existing strings, adding more than 700 new, enhanced optical modules to the 5,160 sensors already embedded in the ice beneath the geographic South Pole.

    The upgrade will include two new types of sensor modules, which will be tested for a ten-times-larger future extension of IceCube – IceCube-Gen2. The modules to be deployed in this first extension will be two to three times more sensitive than the ones that make up the current detector. This is an important benefit for neutrino studies, but it becomes even more relevant for planning the larger IceCube-Gen2.

    The $37 million extension, to be deployed during the 2022-23 polar field season, has now secured $23 million in NSF funding. Last fall, the upgrade office was set up, thanks to initial funding from NSF and additional support from international partners in Japan and Germany as well as from Michigan State University and the University of Wisconsin-Madison.

    See the full article here .

    From U Wisconsin IceCube: “The IceCube Upgrade: An international effort”

    The IceCube Upgrade project is an international collaboration made possible not only by support from the National Science Foundation but also thanks to significant contributions from partner institutions in the U.S. and around the world. Our national and international collaborators play a huge role in manufacturing new sensors, developing firmware, and much more. Learn more about a few of our partner institutions below.

    8
    The Chiba University group poses with one of the new D-Egg optical detectors. Credit: Chiba University

    Chiba University is responsible for the new D-Egg optical detectors, 300 of which will be deployed on the new Upgrade strings. A D-Egg is 30 percent smaller than the original IceCube DOM, but its photon detection effective area is twice as large thanks to two 8-inch PMTs in the specially designed egg-shaped vessel made of UV-transparent glass. Its up-down symmetric detection efficiency is expected to improve our precision for measuring Cherenkov light from neutrino interactions. The newly designed flasher devices in the D-Egg will also give a better understanding of optical characteristics in glacial ice to improve the resolution of arrival directions of cosmic neutrinos.

    See the full article here .

    From DESY: “Neutrino observatory IceCube receives significant upgrade”

    6
    Deep down in the perpetual ice of Antarctica IceCube watches out for a faint bluish glow that indicates a rare collision of a cosmic neutrino within the ice. Artist’s concept: DESY, Science Communication Lab

    Particle detector at the South Pole will be expanded to comprise a neutrino laboratory

    The international neutrino observatory IceCube at the South Pole will be considerably expanded in the coming years. In addition to the existing 5160 sensors, a further 700 optical modules will be installed in the perpetual ice of Antarctica. The National Science Foundation in the USA has approved 23 million US dollars for the expansion. The Helmholtz Centres DESY and Karlsruhe Institute of Technology (KIT) are supporting the construction of 430 new optical modules with a total of 5.7 million euros (6.4 million US dollars), which will turn the observatory into a neutrino laboratory. IceCube, for which Germany with a total of nine participating universities and the two Helmholtz Centres is the most important partner after the USA, had published convincing indications last year of a first source of high-energy neutrinos from the cosmos.

    See the full article here .

    See the full articles above .

    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 8:52 pm on March 28, 2019 Permalink | Reply
    Tags: , , , , , , , , , U Wisconsin IceCube and IceCube Gen-2   

    From insideHPC: “Nor-Tech Powers LIGO and IceCube Nobel-Physics Prize-Winning Projects” 

    From insideHPC

    March 28, 2019

    Today HPC integrator Nor-Tech announced participation in two recent Nobel Physics Prize-Winning projects. The company’s HPC gear will help power the Laser Interferometer Gravitational-Wave Observatory (LIGO) project as well as the IceCube neutrino detection experiment.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


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

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

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

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/eLISA the future of gravitational wave research

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018


    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    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

    “We are excited about the amazing discoveries these enhanced detectors will reveal,” said Nor-Tech Executive Vice President Jeff Olson. “This is an energizing time for all of us at Nor-Tech—knowing that the HPC solutions we are developing for two Nobel projects truly are changing our view of the world.”

    LIGO just announced that their detectors are about to come online after a one-year shutdown for hardware upgrades. In preparation for this, LIGO Consortium member University of Wisconsin-Milwaukee upgraded their clusters with Nor-Tech hardware to assist with the computing demands. At UWM they design, build and maintain computational tools, such as Nor-Tech’s supercomputer, that handle LIGO’s massive amounts of data. Nor-Tech completed the most recent update-including Intel Skylake processors-in 2018. The new Skylake-equipped technology is proving to be almost 10 times faster.

    LIGO was awarded a Nobel Prize in 2017. Prior to this, at a Feb. 11, 2016 national media conference, National Science Foundation (NSF) researchers announced the first direct observation of a gravitational wave. This was a paradigm-shifting achievement in the science community. Subsequent gravitational wave detections have confirmed those results.

    In 2018, the LIGO team announced the first visible detection of a neutrino event. This was made possible, in part, by the powerful HPC technology Nor-Tech has been providing to multiple LIGO Consortium institutions since 2005.

    The first Nor-Tech client to win a Nobel Prize in Physics was the IceCube research team, headquartered at the University of Wisconsin-Madison. IceCube is designed specifically to identify neutrinos from space. It’s a cubic kilometer of ice, laced with photo-detectors, located at a dedicated Antarctic research facility.

    Nor-Tech has been working with several of the world’s leading research institutions involved with the IceCube project for more than 10 years; designing, building, and upgrading HPC technology that made exciting neutrino discoveries possible.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded on December 28, 2006, insideHPC is a blog that distills news and events in the world of HPC and presents them in bite-sized nuggets of helpfulness as a resource for supercomputing professionals. As one reader said, we’re sifting through all the news so you don’t have to!

    If you would like to contact me with suggestions, comments, corrections, errors or new company announcements, please send me an email at rich@insidehpc.com. Or you can send me mail at:

    insideHPC
    2825 NW Upshur
    Suite G
    Portland, OR 97239

    Phone: (503) 877-5048

     
  • richardmitnick 1:29 pm on February 23, 2019 Permalink | Reply
    Tags: "An important step towards understanding neutrino masses", , , , , U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “An important step towards understanding neutrino masses” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    22 Feb 2019
    Sílvia Bravo

    Neutrinos are used to investigate a broad spectrum of physics topics, ranging from the extreme universe to the underlying symmetries of nature. These intriguing particles may have the answer to a few, long-standing open questions in physics and astronomy. In particular, neutrinos themselves are the origin of still unresolved and maybe totally new physics.

    One of the main open questions in neutrino physics is the relative mass of the three neutrino types, a property known as the neutrino mass ordering. Is the third neutrino more massive than the other neutrinos, in what scientists call the normal ordering (NO), or is it lighter, referred to as inverted ordering (IO)? In a new paper by the IceCube Collaboration, physicists use the inner and denser DeepCore detector within IceCube to try to answer this question. A weak preference is shown for NO, a result that is complementary to and in agreement with results from other experiments. This paper has been submitted to the European Physical Journal.

    1
    The negative log-likelihood (LLH) as a function of sin2(θ23) for Analysis A, relative to the global minimum LLHmin. The preference for NO over IO is visible over all the range of sin2 (θ23) with the best-fit for both orderings being in the lower octant (sin2 (θ23) < 0.5). Image: IceCube Collaboration

    When neutrinos travel through space and matter, they oscillate, meaning they change their flavor (electron, muon or tau) depending on their energy and the propagation distance. This quantum effect is explained by the fact that neutrino mass states, i.e. those for which the mass is a well-defined property, are not the same as the neutrino flavor states, the states in which neutrinos interact. These mass states are called neutrinos 1, 2 and 3.

    But we know very little about neutrino mass, except that for all neutrinos it is very small and that nature may work fairly differently depending on which neutrino is more massive. Some unification theories, for example, predict a normal mass ordering. Also depending on this mass ordering, the outcomes of a supernova explosion might be different.

    Several current and future long-baseline accelerator experiments, as well as experiments with atmospheric neutrinos and reactor neutrinos, are targeting a precise measurement of the mass ordering. For atmospheric neutrinos, the propagation through Earth induces a small modulation of the oscillation of neutrinos below 15 GeV, at about the lowest neutrino energies detected in IceCube. Interestingly, this modulation depends on the mass ordering. The high statistics of detected neutrinos within IceCube allows us to search for this small effect.

    In this study, researchers performed two independent analyses, both using three years of IceCube data and targeting this challenging measurement of the neutrino mass ordering with low-energy atmospheric neutrinos in IceCube. “When we embarked on this new analysis we were not aware of all the experimental challenges that we had to solve to measure the faint signals of these low-energy neutrinos with a sufficient precision,” says Martin Leuermann, a main analyzer of this study who worked on this analysis as a PhD candidate at RWTH Aachen University.

    Both analyses obtain a consistent result within their uncertainties and a small preference for NO. Although the ordering signature is very weak, it provides a complimentary measurement. Unlike beam experiments, this result is independent of the CP-violating phase, another important parameter for characterizing neutrino oscillations. Another valuable outcome of this study is the successful implementation and verification of analysis methods that have been prototyped for future extensions of IceCube such as PINGU or the imminent IceCube Upgrade.

    The IceCube Upgrade is already underway and is expected to be completed by 2023. It will deploy new sensors within DeepCore, which will greatly enhance the accuracy of detecting these lowest energy neutrinos in IceCube that are most critical for this measurement. “We have now proven that the concept of future extensions of IceCube do work in practice and thus we can look forward to unprecedented measurements of neutrino properties,” says Steven Wren, also a main analyzer of this study who worked on this analysis as a PhD candidate at the University of Manchester.

    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 4:01 pm on February 18, 2019 Permalink | Reply
    Tags: A new technique dubbed STeVE for “starting TeV events, A second technique called LESE for low-energy starting events, , , , Both of these techniques introduce a new online event selection filter that selects starting events based on an initial fast reconstruction, , , Gamma-ray emission, However gamma rays can also be produced in environments where neutrino emission would be disfavored, , Searches combining both techniques result in an effective area comparable to ANTARES which thanks to its location in the Mediterranean Sea has a priori a better neutrino view of our galaxy, STeVE and LESE where tested with 3 and 4 years of IceCube data respectively, The gamma-ray galactic sky shows a large concentration of sources in the Southern Hemisphere, The highest energy gamma rays could be produced in the same mechanisms that produce the highest energy neutrinos, U Wisconsin IceCube and IceCube Gen-2   

    From U Wisconsin IceCube Collaboration: “Improving searches for galactic sources of high-energy neutrinos” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    18 Feb 2019
    Sílvia Bravo

    The search for sources of high-energy neutrinos and cosmic rays has revealed neutrinos from distant galaxies and from all over the sky traveling through the Antarctic ice. Closer sources, though, those that could produce neutrino emission in the Milky Way, have been more elusive.

    In IceCube, the signature of sources such as galactic supernova remnants peaks at low energies, well below 100 TeV, where the large background of atmospheric muons is difficult to filter out. The bulk of galactic neutrino emission is expected in the southern sky, where the Earth cannot serve as a natural filter to remove the million-to-one muon-neutrino signal. In a recent paper by the IceCube Collaboration, two new techniques improve searches at energies from 100 TeV down to 100 GeV. When tested with a few years of IceCube data, these new selections improve the sensitivity and discovery potential, allowing for the first time the search for galactic point-like sources using track events created by muon neutrinos that in many cases are indistinguishable from atmospheric muon tracks. These results have just been submitted to the journal Astroparticle Physics.

    1
    The differential discovery potential at −60° declination for LESE (light blue), STeVE (dark blue), the combined selection (LESE +STeVE) (red), a cascade point-source search (gray), a starting tracks search targeting higher energies (MESE) (gray dashed), throughgoing (light gray dashed), all with the IceCube detector, and of the ANTARES point-like source search (black). In this plot, all results are calculated for an equal three-year exposure. Image: IceCube Collaboration

    Scientists have speculated that at high energies neutrino emission should be associated with gamma-ray emission, since the highest energy gamma rays could be produced in the same mechanisms that produce the highest energy neutrinos. However, gamma rays can also be produced in environments where neutrino emission would be disfavored.

    The gamma-ray galactic sky shows a large concentration of sources in the Southern Hemisphere, where both the galactic center and the majority of the galactic plane are seen from Earth. This is, thus, a region worth exploring with IceCube to look for potential neutrino emission from the same sources that produce the gamma rays.

    However, the most successful searches for high-energy neutrinos select particle interactions that start in the detector—both cascade- and track-like events—or track-like events that come from the northern sky. Track-like events are those that provide a good pointing resolution, which on average is well below 1 degree.

    In previous searches for astrophysical neutrinos using events with the interaction vertex within the detector, a fairly high energy cut was also applied to obtain an efficient selection. The concern is that the majority of galactic neutrino emission could happen at lower energies and, thus, might be removed with this cut. To lower this energy threshold and still preserve a good pointing resolution in the southern sky, researchers have looked closer at track events in IceCube.

    In a new technique dubbed STeVE, for “starting TeV events,” the selection focuses on neutrino events between 10 and 100 TeV and uses techniques developed in a previous IceCube analysis (link to MESE news 414) to remove the background of multiple parallel atmospheric muon events, which has proved to be a resistant background at low energies. In addition, this event selection strategy exploits the difference in the observed photon pattern of bundles of low-energy atmospheric muons compared to individual high-energy muons.

    In a second technique, called LESE, for low-energy starting events, the selection was optimized for neutrinos below 10 TeV. At low energies and due to the small granularity of the IceCube detector, with strings of sensors deployed at horizontal distances of 125 meters, it’s easier for muon tracks to enter the detector without significant energy deposition detected by the outer layers of sensors, which mimics a muon neutrino interacting within the detector volume. LESE aims at selecting track-like events with energies as low as 100 GeV, leveraging the experience gained with veto-based selection techniques in searches for dark matter.

    Both of these techniques introduce a new online event selection filter that selects starting events based on an initial fast reconstruction. This new filter is the first to accept starting events from the entire southern sky while maintaining as large as possible active detector volume.

    STeVE and LESE where tested with 3 and 4 years of IceCube data, respectively, in a search for sources of astrophysical neutrinos anywhere in the southern sky and for neutrino emission from the direction of 96 known gamma-ray sources. No significant excess of neutrino emission was found, but the techniques have proven to be sensitive to strong galactic sources of low-energy astrophysical neutrinos.

    “Studying starting events from the southern sky at these energies poses many new challenges,” explains Rickard Ström, a main analyzer who worked on this study as a PhD candidate at Uppsala University. “We leveraged expertise from previous searches for point sources and exotic signatures such as dark matter. This was the first time IceCube was able to study point sources in the southern sky at these energies and using tracks with degree precision,” adds Ström.

    Searches combining both techniques result in an effective area comparable to ANTARES, which thanks to its location in the Mediterranean Sea has a priori a better neutrino view of our galaxy. STeVE and LESE selections reduce the muon background to a few thousand events per year and significantly improve IceCube’s sensitive and discovery potential of point-like sources in the southern sky with neutrinos with energies below 100 TeV.

    From From U Wisconsin IceCube Collaboration

    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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