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  • richardmitnick 7:42 pm on January 16, 2020 Permalink | Reply
    Tags: "Study finds billions of quantum entangled electrons in ‘strange metal", , Particle Physics, , , Quantum entanglement is the basis for storage and processing of quantum information., , Terahertz spectroscopy, With strange metals there is an unusual connection between electrical resistance and temperature.   

    From Rice University: “Study finds billions of quantum entangled electrons in ‘strange metal” 

    Rice U bloc

    From Rice University

    January 16, 2020
    Jade Boyd

    Physicists provide direct evidence of entanglement’s role in quantum criticality.

    In a new study, U.S. and Austrian physicists have observed quantum entanglement among “billions of billions” of flowing electrons in a quantum critical material.

    Junichiro Kono (left) and Qimiao Si in Kono’s Rice University laboratory in December 2019. (Photo by Jeff Fitlow/Rice University)

    The research, which appears this week in Science, examined the electronic and magnetic behavior of a “strange metal” compound of ytterbium, rhodium and silicon as it both neared and passed through a critical transition at the boundary between two well-studied quantum phases.

    The study at Rice University and Vienna University of Technology (TU Wien) provides the strongest direct evidence to date of entanglement’s role in bringing about quantum criticality, said study co-author Qimiao Si of Rice.

    “When we think about quantum entanglement, we think about small things,” Si said. “We don’t associate it with macroscopic objects. But at a quantum critical point, things are so collective that we have this chance to see the effects of entanglement, even in a metallic film that contains billions of billions of quantum mechanical objects.”

    Si, a theoretical physicist and director of the Rice Center for Quantum Materials (RCQM), has spent more than two decades studying what happens when materials like strange metals and high-temperature superconductors change quantum phases. Better understanding such materials could open the door to new technologies in computing, communications and more.

    The international team overcame several challenges to get the result. TU Wien researchers developed a highly complex materials synthesis technique to produce ultrapure films containing one part ytterbium for every two parts rhodium and silicon (YbRh2Si2). At absolute zero temperature, the material undergoes a transition from one quantum phase that forms a magnetic order to another that does not.

    Physicist Silke Bühler-Paschen of the Vienna University of Technology (Photo by Luisa Puiu/TU Wien)

    At Rice, study co-lead author Xinwei Li, then a graduate student in the lab of co-author and RCQM member Junichiro Kono, performed terahertz spectroscopy experiments on the films at temperatures as low as 1.4 Kelvin. The terahertz measurements revealed the optical conductivity of the YbRh2Si2 films as they were cooled to a quantum critical point that marked the transition from one quantum phase to another.

    “With strange metals, there is an unusual connection between electrical resistance and temperature,” said corresponding author Silke Bühler-Paschen of TU Wien’s Institute for Solid State Physics. “In contrast to simple metals such as copper or gold, this does not seem to be due to the thermal movement of the atoms, but to quantum fluctuations at the absolute zero temperature.”

    To measure optical conductivity, Li shined coherent electromagnetic radiation in the terahertz frequency range on top of the films and analyzed the amount of terahertz rays that passed through as a function of frequency and temperature. The experiments revealed “frequency over temperature scaling,” a telltale sign of quantum criticality, the authors said.

    Kono, an engineer and physicist in Rice’s Brown School of Engineering, said the measurements were painstaking for Li, who’s now a postdoctoral researcher at the California Institute of Technology. For example, only a fraction of the terahertz radiation shined onto the sample passed through to the detector, and the important measurement was how much that fraction rose or fell at different temperatures.

    Former Rice University graduate student Xinwei Li in 2016 with the terahertz spectrometer he later used to measure entanglement in the conduction electrons flowing through a “strange metal” compound of ytterbium, rhodium and silicon. (Photo by Jeff Fitlow/Rice University)

    “Less than 0.1% of the total terahertz radiation was transmitted, and the signal, which was the variation of conductivity as a function of frequency, was a further few percent of that,” Kono said. “It took many hours to take reliable data at each temperature to average over many, many measurements, and it was necessary to take data at many, many temperatures to prove the existence of scaling.

    “Xinwei was very, very patient and persistent,” Kono said. “In addition, he carefully processed the huge amounts of data he collected to unfold the scaling law, which was really fascinating to me.”

    Making the films was even more challenging. To grow them thin enough to pass terahertz rays, the TU Wien team developed a unique molecular beam epitaxy system and an elaborate growth procedure. Ytterbium, rhodium and silicon were simultaneously evaporated from separate sources in the exact 1-2-2 ratio. Because of the high energy needed to evaporate rhodium and silicon, the system required a custom-made ultrahigh vacuum chamber with two electron-beam evaporators.

    “Our wild card was finding the perfect substrate: germanium,” said TU Wien graduate student Lukas Prochaska, a study co-lead author. The germanium was transparent to terahertz, and had “certain atomic distances (that were) practically identical to those between the ytterbium atoms in YbRh2Si2, which explains the excellent quality of the films,” he said.

    Si recalled discussing the experiment with Bühler-Paschen more than 15 years ago when they were exploring the means to test a new class of quantum critical point. The hallmark of the quantum critical point that they were advancing with co-workers is that the quantum entanglement between spins and charges is critical.

    Former Rice University graduate student Xinwei Li (left) and Professor Junichiro Kono in 2016 with the terahertz spectrometer Li used to measure quantum entanglement in YbRh2Si2. (Photo by Jeff Fitlow/Rice University)

    “At a magnetic quantum critical point, conventional wisdom dictates that only the spin sector will be critical,” he said. “But if the charge and spin sectors are quantum-entangled, the charge sector will end up being critical as well.”

    At the time, the technology was not available to test the hypothesis, but by 2016, the situation had changed. TU Wien could grow the films, Rice had recently installed a powerful microscope that could scan them for defects, and Kono had the terahertz spectrometer to measure optical conductivity. During Bühler-Paschen’s sabbatical visit to Rice that year, she, Si, Kono and Rice microscopy expert Emilie Ringe received support to pursue the project via an Interdisciplinary Excellence Award from Rice’s newly established Creative Ventures program.

    “Conceptually, it was really a dream experiment,” Si said. “Probe the charge sector at the magnetic quantum critical point to see whether it’s critical, whether it has dynamical scaling. If you don’t see anything that’s collective, that’s scaling, the critical point has to belong to some textbook type of description. But, if you see something singular, which in fact we did, then it is very direct and new evidence for the quantum entanglement nature of quantum criticality.”

    Si said all the efforts that went into the study were well worth it, because the findings have far-reaching implications.

    “Quantum entanglement is the basis for storage and processing of quantum information,” Si said. “At the same time, quantum criticality is believed to drive high-temperature superconductivity. So our findings suggest that the same underlying physics — quantum criticality — can lead to a platform for both quantum information and high-temperature superconductivity. When one contemplates that possibility, one cannot help but marvel at the wonder of nature.”

    Si is the Harry C. and Olga K. Wiess Professor in Rice’s Department of Physics and Astronomy. Kono is a professor in Rice’s departments of Electrical and Computer Engineering, Physics and Astronomy, and Materials Science and NanoEngineering and the director of Rice’s Applied Physics Graduate Program. Ringe is now at the University of Cambridge.

    Additional co-authors include Maxwell Andrews, Maximilian Bonta, Werner Schrenk, Andreas Limbeck and Gottfried Strasser, all of the TU Wien; Hermann Detz, formerly of TU Wien and currently at Brno University; Elisabeth Bianco, formerly of Rice and currently at Cornell University; Sadegh Yazdi, formerly of Rice and currently at the University of Colorado Boulder; and co-lead author Donald MacFarland, formerly of TU Wien and currently at the University at Buffalo.

    The research was supported by the European Research Council, the Army Research Office, the Austrian Science Fund, the European Union’s Horizon 2020 program, the National Science Foundation, the Robert A. Welch Foundation, Los Alamos National Laboratory and Rice University.

    RCQM leverages global partnerships and the strengths of more than 20 Rice research groups to address questions related to quantum materials. RCQM is supported by Rice’s offices of the provost and the vice provost for research, the Wiess School of Natural Sciences, the Brown School of Engineering, the Smalley-Curl Institute and the departments of Physics and Astronomy, Electrical and Computer Engineering, and Materials Science and NanoEngineering.

    See the full article here .


    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

  • richardmitnick 10:07 am on January 15, 2020 Permalink | Reply
    Tags: "Galactic gamma-ray sources reveal birthplaces of high-energy particles", , , Joint US-Mexico-European HAWC Observatory, , Particle Physics, ,   

    From Los Alamos National Laboratory: “Galactic gamma-ray sources reveal birthplaces of high-energy particles” 

    LANL bloc

    From Los Alamos National Laboratory

    Jan. 14, 2020
    ames Riordon
    Communications Office
    (505) 667-3272

    Researchers with the joint US-Mexico-European HAWC Observatory have identified a host of galactic sources of super-high-energy gamma rays.

    HAWC High Altitude Čerenkov Experiment, a
    US Mexico Europe collaboration located on the flanks of the Sierra Negra volcano in the Mexican state of Puebla at an altitude of 4100 meters(13,500ft), at WikiMiniAtlas 18°59′41″N 97°18′30.6″W. searches for cosmic rays

    A map of the galactic plane indicates the highest energy gamma ray sources yet discovered. The sources comprise a new catalog compiled by the members of the High Altitude Water Čerenkov Observatory collaboration.

    Nine sources of extremely high-energy gamma rays comprise a new catalog compiled by researchers with the High-Altitude Water Čerenkov (HAWC) Gamma-Ray Observatory. All produce gamma rays with energies over 56 trillion electron volts (TeV) and three emit gamma rays extending to 100 TeV and beyond, making these the highest-energy sources ever observed in our galaxy. The catalog helps to explain where the particles originate and how they are accelerated to such extremes.

    “The Earth is constantly being bombarded with charged particles called cosmic rays, but because they are charged, they bend in magnetic fields and don’t point back to their sources. We rely on gamma rays, which are produced close to the sources of the cosmic rays, to narrow down their origins,” said Kelly Malone, an astrophysicist in the Neutron Science and Technology group at Los Alamos National Laboratory and a member of the HAWC scientific collaboration. “There are still many unanswered questions about cosmic-ray origins and acceleration. High energy gamma rays are produced near cosmic-ray sites and can be used to probe cosmic-ray acceleration. However, there is some ambiguity in using gamma rays to study this, as high-energy gamma rays can also be produced via other mechanisms, such as lower-energy photons scattering off of electrons, which commonly occurs near pulsars.”

    Newly Discovered Gamma Ray Sources Have the Highest Energy Ever Recorded.

    The newly cataloged astrophysical gamma-ray sources have energies about 10 times higher than can be produced using experimental particle colliders on Earth. While higher-energy astrophysical particles have been previously detected, this is the first time specific galactic sources have been pinpointed. All of the sources have extremely energetic pulsars (highly magnetized rotating neutron stars) nearby. The number of sources detected may indicate that ultra-high-energy emission is a generic feature of powerful particle winds coming from pulsars embedded in interstellar gas clouds known as nebulae, and that more detections will be forthcoming.

    The HAWC Gamma-Ray Observatory consists of an array of water-filled tanks sitting high on the slopes of the Sierra Negra volcano in Puebla, Mexico, where the atmosphere is thin and offers better conditions for observing gamma rays. When these gamma rays strike molecules in the atmosphere they produce showers of energetic particles. Although nothing can travel faster than the speed of light in a vacuum, light moves more slowly through water. As a result, some particles in cosmic ray showers travel faster than light in the water inside the HAWC detector tanks. The faster-than-light particles, in turn, produce characteristic flashes of light called Čerenkov radiation. By recording the Čerenkov flashes in the HAWC water tanks, researchers can reconstruct the sources of the particle showers to learn about the particles that caused them in the first place.

    The HAWC collaborators plan to continue searching for the sources of high-energy cosmic rays. By combining their data with measurements from other types of observatories such as neutrino, x-ray, radio and optical telescopes, they hope to disentangle the astrophysical mechanisms that produce the cosmic rays that continuously rain down on our planet.

    Science paper:
    Multiple Galactic Sources with Emission Above 56 TeV Detected by HAWC
    Physical Review Letters

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Los Alamos National Laboratory’s mission is to solve national security challenges through scientific excellence.

    LANL campus

    Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and URS for the Department of Energy’s National Nuclear Security Administration.

    Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

    Operated by Los Alamos National Security, LLC for the U.S. Dept. of Energy’s NNSA

  • richardmitnick 5:32 pm on January 14, 2020 Permalink | Reply
    Tags: ANTARES, , , Particle Physics, ,   

    From U Wisconsin IceCube Collaboration and ANTARES: “ANTARES and IceCube combine forces to search for southern sky neutrino sources” 

    U Wisconsin ICECUBE neutrino detector at the South Pole

    From From U Wisconsin IceCube Collaboration

    14 Jan 2020
    Madeleine O’Keefe

    Teamwork makes the dream work. Especially when that dream is to find sources of elusive particles called neutrinos.

    Neutrinos are chargeless, nearly massless subatomic particles. These elusive particles are abundantly produced in nuclear fusion processes in our sun or the natural radioactivity of Earth. In rare cases, we also observe high-energy neutrinos from outer space, known as astrophysical neutrinos. They fly through light-years of space at close to the speed of light without being tugged around by magnetic fields or other forces; this makes them ideal astronomical messengers, as they bring us information from the most enigmatic objects in the cosmos. But we still don’t know where they originate.

    The IceCube Neutrino Observatory in Antarctica is one experiment looking for sources of these enigmatic particles. IceCube does this with an array of 5,160 optical detectors buried in a cubic kilometer of South Pole ice; when a neutrino from outer space reaches Antarctica with enough energy, it can hit an atom in the ice and produce another particle that flies through IceCube, trailed by a cone of light called Čerenkov radiation. That cone of light triggers the detectors it passes, leaving clusters of lit-up detectors behind it.

    Meanwhile, floating in the Mediterranean Sea is a similar neutrino experiment called ANTARES.


    The IceCube Collaboration recently conducted a combined IceCube-ANTARES search for neutrino point-like and extended sources in the southern sky. They didn’t find any significant evidence for cosmic neutrino sources, but the analysis shows the strong potential for combining data sets from both experiments. Their results were recently submitted to The Astrophysical Journal.

    This sky map shows the result of the search for point-like sources in the whole southern sky. Higher values of -log10(p-value) indicate more significant directions. The red contour shows the position of the most significant cluster of events, which was not significant enough to be considered a source. Credit: IceCube Collaboration

    It’s an exciting time for neutrino astronomy. IceCube’s past few years of research have yielded promising results, including the discovery of the first evidence of neutrinos coming from an astrophysical source. But the origins of most of the astrophysical neutrinos that reach Earth remain unknown.

    So researchers around the world are continuing to look for neutrino sources. Giulia Illuminati of the Instituto de Física Corpuscular in Valencia, Spain, led this search, which combined data sets from IceCube and ANTARES.

    “The motivation behind this analysis lies in the fact that ANTARES and IceCube, thanks to their different sizes and locations, complement each other when looking for neutrino sources in the southern sky,” she says.

    ANTARES’s location in the Mediterranean results in a lower background for neutrino source hunting in the Southern Hemisphere, while IceCube’s larger size gives it a higher detection capability. Together, these characteristics mean an increased chance to detect sources of astrophysical neutrinos in the southern sky.

    Illuminati and her collaborators performed five types of searches for point-like and extended sources of astrophysical neutrinos using ANTARES and IceCube data. (Technically, all neutrino sources are “extended,” but when they appear on the celestial sphere with a size smaller than IceCube’s angular resolution, they cannot be resolved and are called “point-like.”)

    In the first two searches, they scanned the full southern sky and a restricted region around the Galactic Center to look for significant emission of cosmic neutrinos from point-like and extended sources. In the third search, they investigated the positions of 57 astrophysical objects in a predefined list of candidate point-like emitters of high-energy neutrinos. Finally, they performed dedicated searches at the locations of two promising neutrino source candidates: the supermassive black hole Sagittarius A* and the shell-type supernova remnant RXJ 1713.7-3946.

    Ultimately, they did not find any significant point-like or extended neutrino emission, but they derived upper limits on the neutrino flux from the various analyzed sources. Even without a significant discovery, this analysis proved the high potential of joint searches for neutrino sources with ANTARES and IceCube. By combining the data sets of the two detectors, the researchers were able to improve the sensitivity in different regions of the southern sky by about a factor of 2 compared to individual analyses.

    “These results strongly motivate a joint analysis of future data sets, not only of the ANTARES and the IceCube telescopes but also of the future detectors KM3NeT and IceCube-Gen2 [below],” says Illuminati.

    KM3NeT Digital Optical Module (DOM) in the laboratory .www.km3net.org

    Artist’s expression of the KM3NeT neutrino telescope

    It relies on the same principle as IceCube: It’s another three-dimensional array of optical detectors in a transparent medium (here, water instead of ice). If a high-energy neutrino hits an atom in the water, it will produce a particle and Cherenkov light that triggers the optical modules in the sea.

    The IceCube Collaboration recently conducted a combined IceCube-ANTARES search for neutrino point-like and extended sources in the southern sky. They didn’t find any significant evidence for cosmic neutrino sources, but the analysis shows the strong potential for combining data sets from both experiments. Their results were recently submitted to The Astrophysical Journal.

    See the full article here .


    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 3:29 pm on January 14, 2020 Permalink | Reply
    Tags: , , , , , Dilepton channel, Drell–Yan process, Particle Physics, , Searching for new physics in the TeV regime by looking for the decays of new particles., The dark photon (Zd)?   

    From CERN Courier: “CMS goes scouting for dark photons” 

    From CERN Courier

    6 December 2019
    A report from the CMS experiment

    One of the best strategies for searching for new physics in the TeV regime is to look for the decays of new particles. The CMS collaboration has searched in the dilepton channel for particles with masses above a few hundred GeV since the start of LHC data taking. Thanks to newly developed triggers, the searches are now being extended to the more difficult lower range of masses. A promising possible addition to the Standard Model (SM) that could exist in this mass range is the dark photon (Zd). Its coupling with SM particles and production rate depend on the value of a kinetic mixing coefficient ε, and the resulting strength of the interaction of the Zd with ordinary matter may be several orders of magnitude weaker than the electroweak interaction.

    The CMS collaboration has recently presented results of a search for a narrow resonance decaying to a pair of muons in the mass range from 11.5 to 200 GeV. This search looks for a strikingly sharp peak on top of a smooth dimuon mass spectrum that arises mainly from the Drell–Yan process. At masses below approximately 40 GeV, conventional triggers are the main limitation for this analysis as the thresholds on the muon transverse momenta (pT), which are applied online to reduce the rate of events saved for offline analysis, introduce a significant kinematic acceptance loss, as evident from the red curve in figure 1.

    Fig. 1. Dimuon invariant-mass distributions obtained from data collected by the standard dimuon triggers (red) and the dimuon scouting triggers (green).

    A dedicated set of high-rate dimuon “scouting” triggers, with some additional kinematic constraints on the dimuon system and significantly lower muon pT thresholds, was deployed during Run 2 to overcome this limitation. Only a minimal amount of high-level information from the online reconstruction is stored for the selected events. The reduced event size allows significantly higher trigger rates, up to two orders of magnitude higher than the standard muon triggers. The green curve in figure 1 shows the dimuon invariant mass distribution obtained from data collected with the scouting triggers. The increase in kinematic acceptance for low masses can be well appreciated.

    The full data sets collected with the muon scouting and standard dimuon triggers during Run 2 are used to probe masses below 45 GeV, and between 45 and 200 GeV, respectively, excluding the mass range from 75 to 110 GeV where Z-boson production dominates. No significant resonant peaks are observed, and limits are set on ε2 at 90% confidence as a function of the ZD mass (figure 2). These are among the world’s most stringent constraints on dark photons in this mass range.

    Fig. 2. Upper limits on ε2 as a function of the ZD mass. Results obtained with data collected by the dimuon scouting triggers are to the left of the dashed line. Constraints from measurement of the electroweak observables are shown in light blue.

    See the full article here .

    Please help promote STEM in your local schools.

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    CERN/ATLAS detector


    CERN/ALICE Detector

    CERN CMS New

    CERN LHCb New II


    CERN map

    CERN LHC Grand Tunnel

    CERN LHC particles

  • richardmitnick 1:07 pm on January 14, 2020 Permalink | Reply
    Tags: A pursuit that stretches from underground particle colliders to orbiting telescopes with all manner of ground-based observatories in between., , , , , , , , , Particle Physics, The astronomer missed her Nobel Prize [in my view a crime of old white men], ,   

    From The New York Times: Women in STEM-“Vera Rubin Gets a Telescope of Her Own” 

    From The New York Times

    Jan. 11, 2020
    Dennis Overbye

    The astronomer missed her Nobel Prize [in my view a crime of old white men]. But she now has a whole new observatory to her name.

    The astronomer Vera Rubin at the Lowell Observatory in Flagstaff, Ariz., in 1965.Credit: via Carnegie Institution of Science

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

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

    Vera Rubin, a young astronomer at the Carnegie Institution in Washington, was on the run in the 1970s when she overturned the universe.

    Seeking refuge from the controversies and ego-bashing of cosmology, she decided to immerse herself in the pearly swirlings of spiral galaxies, only to find that there was more to them than she and almost everybody else had thought.

    For millenniums, humans had presumed that when we gaze out at the universe, what we see is a fair representation of reality. Dr. Rubin, with her colleague Kent Ford, discovered that was not true. The universe — all those galaxies and the vast spaces between — was awash with dark matter, an invisible something with sufficient gravity to mold the large scale structures of the universe.

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed by Vera Rubin

    Esteemed astronomers dismissed her findings at first. But half a century later, the still futile quest to identify this “dark matter” is a burning question for both particle physics and astronomy. It’s a pursuit that stretches from underground particle colliders to orbiting telescopes, with all manner of ground-based observatories in between.

    Last week the National Science Foundation announced that the newest observatory joining this cause will be named the Vera C. Rubin Observatory. The name replaces the mouthful by which the project was previously known: the Large Synoptic Survey Telescope, or L.S.S.T.

    The Vera C. Rubin Observatory, formerly the Large Synoptic Survey Telescope, under construction in Cerro Pachon, Chile. Credit: LSST Project/NSF/AURA

    The Rubin Observatory joins a handful of smaller astronomical facilities that have been named for women. The Maria Mitchell Observatories in Nantucket, Mass., is named after the first American woman to discover a comet. The Swope telescope, at Carnegie’s Las Campanas Observatory in Chile, is named after Henrietta Swope, who worked at the Harvard College Observatory in the early 20th century. She used a relationship between the luminosities and periodicities of variable stars to measure distances to galaxies.

    And finally there is the new Annie Maunder Astrographic Telescope at the venerable Royal Greenwich Observatory, just outside London. It is named after Annie Maunder, who with her husband Walter made pioneering observations of the sun and solar cycle of sunspots in the late 1800s.

    Heros of science, all of them.

    In a field known for grandiloquent statements and frightening intellectual ambitions, Dr. Rubin was known for simple statements about how stupid we are. In an interview in 2000 posted on the American Museum of Natural History website, Dr. Rubin said:

    “In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10. That’s probably a good number for the ratio of our ignorance to knowledge. We’re out of kindergarten, but only in about third grade.”

    Once upon a time cosmologists thought there might be enough dark matter in the universe for its gravity to stop the expansion of the cosmos and pull everything back together in a Big Crunch. Then astronomers discovered an even more exotic feature of the universe, now called dark energy, which is pushing the galaxies apart and speeding up the cosmic expansion.

    Dark Energy Survey

    Dark Energy Camera [DECam], built at FNAL

    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    These discoveries have transformed cosmology still further, into a kind of Marvel Comics super-struggle between invisible, titanic forces. One, dark matter, pulls everything together toward its final doom; the other, dark energy, pushes everything apart toward the ultimate dispersal, some times termed the Big Rip. The rest of us, the terrified populace looking up at this cosmic war, are bystanders, made of atoms, which are definitely a minority population of the universe. Which force will ultimately prevail? Which side should we root for?

    Until recently the money was on dark energy and eventual dissolution of the cosmos. But lately cracks have appeared in the data, suggesting that additional forces may be at work beneath the surface of our present knowledge.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 11:55 am on January 14, 2020 Permalink | Reply
    Tags: "A voyage to the heart of the neutrino", , , , , Particle Physics, , SNOLAB- a Canadian underground physics laboratory at a depth of 2 km in Vale's Creighton nickel mine in Sudbury Ontario Canada., Super-Kamiokande experiment located under Mount Ikeno near the city of Hida Gifu Prefecture Japan, The Karlsruhe Tritium Neutrino (KATRIN) experiment, The most abundant particles in the universe besides photons., The three neutrino mass eigenstates, We know now that the three neutrino flavour states we observe in experiments – νe; νμ; and ντ – are mixtures of three neutrino mass states.   

    From CERN Courier: “A voyage to the heart of the neutrino” 

    From CERN Courier

    10 January 2020

    The Karlsruhe Tritium Neutrino (KATRIN) experiment has begun its seven-year-long programme to determine the absolute value of the neutrino mass.

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

    On 11 June 2018, a tense silence filled the large lecture hall of the Karlsruhe Institute of Technology (KIT) in Germany.


    Karlsruhe Institute Of Technology (KIT)

    Karlsruhe Institute of Technology (KIT) in Germany.

    In front of an audience of more than 250 people, 15 red buttons were pressed simultaneously by a panel of senior figures including recent Nobel laureates Takaaki Kajita and Art McDonald. At the same time, operators in the control room of the Karlsruhe Tritium Neutrino (KATRIN) experiment lowered the retardation voltage of the apparatus so that the first beta electrons were able to pass into KATRIN’s giant spectrometer vessel. Great applause erupted when the first beta electrons hit the detector.

    In the long history of measuring the tritium beta-decay spectrum to determine the neutrino mass, the ensuing weeks of KATRIN’s first data-taking opened a new chapter. Everything worked as expected, and KATRIN’s initial measurements have already propelled it into the top ranks of neutrino experiments. The aim of this ultra-high-precision beta-decay spectroscope, more than 15 years in the making, is to determine, by the mid-2020s, the absolute mass of the neutrino.

    Massive discovery

    Since the discovery of the oscillation of atmospheric neutrinos by the Super-Kamiokande experiment in 1998, and of the flavour transitions of solar neutrinos by the SNO experiment shortly afterwards, it was strongly implied that neutrino masses are not zero, but big enough to cause interference between distinct mass eigenstates as a neutrino wavepacket evolves in time. We know now that the three neutrino flavour states we observe in experiments – νe, νμ and ντ – are mixtures of three neutrino mass states.

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

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

    SNOLAB, Sudbury, Ontario, Canada.

    Though not massless, neutrinos are exceedingly light. Previous experiments designed to directly measure the scale of neutrino masses in Mainz and Troitsk produced an upper limit of 2 eV for the neutrino mass – a factor 250,000 times smaller than the mass of the otherwise lightest massive elementary particle, the electron. Nevertheless, neutrino masses are extremely important for cosmology as well as for particle physics. They have a number density of around 336 cm–3, making them the most abundant particles in the universe besides photons, and therefore play a distinct role in the formation of cosmic structure. Comparing data from the Planck satellite together with data from galaxy surveys (baryonic acoustic oscillations) with simulations of the evolution of structure yields an upper limit on the sum of all three neutrino masses of 0.12 eV at 95% confidence within the framework of the standard Lambda cold-dark matter (ΛCDM) cosmological model.

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
    Alex Mittelmann, Coldcreation

    Considerations of “naturalness” lead most theorists to speculate that the exceedingly tiny neutrino masses do not arise from standard Yukawa couplings to the Higgs boson, as per the other fermions, but are generated by a different mass mechanism. Since neutrinos are electrically neutral, they could be identical to their antiparticles, making them Majorana particles. Via the so-called seesaw mechanism, this interesting scenario would require a new and very high particle mass scale to balance the smallness of the neutrino masses, which would be unreachable with present accelerators.

    Inner space KATRIN’s main spectrometer, the largest ultra-high-vacuum vessel in the world, contains a dual-layer electrode system comprising 23,000 wires to shield the inner volume from charged particles. Credit: KATRIN

    As neutrino oscillations arise due to interference between mass eigenstates, neutrino-oscillation experiments are only able to determine splittings between the squares of the neutrino mass eigenstates. Three experimental avenues are currently being pursued to determine the neutrino mass. The most stringent upper limit is currently the model-dependent bound set by cosmological data, as already mentioned, which is valid within the ΛCDM model. A second approach is to search for neutrinoless double-beta decay, which allows a statement to be made about the size of the neutrino masses but presupposes the Majorana nature of neutrinos.

    U Washington Majorana Demonstrator Experiment at SURF

    The third approach – the one adopted by KATRIN – is the direct determination of the neutrino mass from the kinematics of a weak process such as beta decay, which is completely model-independent and depends only on the principle of energy and momentum conservation.

    Fig. 1. The beta spectrum of tritium (left), showing in detail the effect of different neutrino masses on the endpoint (right). Credit: CERN

    The direct determination of the neutrino mass relies on the precise measurement of the shape of the beta electron spectrum near the endpoint, which is governed by the available phase space (figure 1). This spectral shape is altered by the neutrino mass value: the smaller the mass, the smaller the spectral modification. One would expect to see three modifications, one for each neutrino mass eigenstate. However, due to the tiny neutrino mass differences, a weighted sum is observed. This “average electron neutrino mass” is formed by the incoherent sum of the squares of the three neutrino mass eigenstates, which contribute to the electron neutrino according to the PMNS neutrino-mixing matrix. The super-heavy hydrogen isotope tritium is ideal for this purpose because it combines a very low endpoint energy, Eo, of 18.6 keV and a short half-life of 12.3 years with a simple nuclear and atomic structure.

    KATRIN is born

    Around the turn of the millennium, motivated by the neutrino oscillation results, Ernst Otten of the University of Mainz and Vladimir Lobashev of INR Troitsk proposed a new, much more sensitive experiment to measure the neutrino mass from tritium beta decay. To this end, the best methods from the previous experiments in Mainz, Troitsk and Los Alamos were to be combined and upscaled by up to two orders of magnitude in size and precision. Together with new technologies and ideas, such as laser Raman spectroscopy or active background reduction methods, the apparatus would increase the sensitivity to the observable in beta decay (the square of the electron antineutrino mass) by a factor of 100, resulting in a neutrino-mass sensitivity of 0.2 eV. Accordingly, the entire experiment was designed to the limits of what was feasible and even beyond (see “Technology transfer delivers ultimate precision” box).

    Precise The electron transport and tritium retention system. Credit: KIT

    Many technologies had to be pushed to the limits of what was feasible or even beyond. KATRIN became a CERN-recognised experiment (RE14) in 2007 and the collaboration worked with CERN experts in many areas to achieve this. The KATRIN main spectrometer is the largest ultra-high vacuum vessel in the world, with a residual gas pressure in the range of 10–11 mbar – a pressure that is otherwise only found in large volumes inside the LHC ring – equivalent to the pressure recorded at the lunar surface.

    Even though the inner surface was instrumented with a complex dual-layer wire electrode system for background suppression and electric-field shaping, this extreme vacuum was made possible by rigorous material selection and treatment in addition to non-evaporable getter technology developed at CERN. KATRIN’s almost 40 m-long chain of superconducting magnets with two large chicanes was put into operation with the help of former CERN experts, and a 223Ra source was produced at ISOLDE for background studies at KATRIN.

    CERN ISOLDE Looking down into the ISOLDE experimental hall

    A series of 83mKr conversion electron sources based on implanted 83Rb for calibration purposes was initially produced at ISOLDE. At present these are produced by KATRIN collaborators and further developed with regard to line stability.

    Conversely, the KATRIN collaboration has returned its knowledge and methods to the community. For example, the ISOLDE high-voltage system was calibrated twice with the ppm-accuracy KATRIN voltage dividers, and the magnetic and electrical field calculation and tracking programme KASSIOPEIA developed by KATRIN was published as open source and has become the standard for low-energy precision experiments. The fast and precise laser Raman spectroscopy developed for KATRIN is also being applied to fusion technology.

    KIT was soon identified as the best place for such an experiment, as it had the necessary experience and infrastructure with the Tritium Laboratory Karlsruhe. The KIT board of directors quickly took up this proposal and a small international working group started to develop the project. At a workshop at Bad Liebenzell in the Black Forest in January 2001, the project received so much international support that KIT, together with nearly all the groups from the previous neutrino-mass experiments, founded the KATRIN collaboration. Currently, the 150-strong KATRIN collaboration comprises 20 institutes from six countries.

    It took almost 16 years from the first design to complete KATRIN, largely because many new technologies had to be developed, such as a novel concept to limit the temperature fluctuations of the huge tritium source to the mK scale at 30 K or the high-voltage stabilisation and calibration to the 10 mV scale at 18.6 kV. The experiment’s two most important and also most complex components are the gaseous, windowless molecular tritium source (WGTS) and the very large spectrometer. In the WGTS, tritium gas is introduced in the midpoint of the 10 m-long beam tube, where it flows out to both sides to be pumped out again by turbomolecular pumps. After being partially cleaned it is re-injected, yielding a closed tritium cycle. This results in an almost opaque column density with a total decay rate of 1011 per second. The beta electrons are guided adiabatically to a tandem of a pre- and a main spectrometer by superconducting magnets of up to 6 T. Along the way, differential and cryogenic pumping sections including geometric chicanes reduce the tritium flow by more than 14 orders of magnitude to keep the spectrometers free of tritium (figure 2).

    Fig. 2. The 70 m-long KATRIN setup showing the key stages and components. Credit: CERN

    The KATRIN spectrometers operate as so-called MAC-E filters, whereby electrons are guided by two superconducting solenoids at either end and their momenta are collimated by the magnetic field gradient. This “magnetic bottle” effect transforms almost all kinetic energy into longitudinal energy, which is filtered by an electrostatic retardation potential so that only electrons with enough energy to overcome the barrier are able to pass through. The smaller pre-spectrometer blocks the low-energy part of the beta spectrum (which carries no information on the neutrino mass), while the 10 m-diameter main spectrometer provides a much sharper filter width due to its huge size.

    The transmitted electrons are detected by a high-resolution segmented silicon detector. By varying the retarding potential of the main spectrometer, a narrow region of the beta spectrum of several tens of eV below the endpoint is scanned, where the imprint of a non-zero neutrino mass is maximal. Since the relative fraction of the tritium beta spectrum in the last 1 eV below the endpoints amounts to just 2 × 10–13, KATRIN demands a tritium source of the highest intensity. Of equal importance is the high precision needed to understand the measured beta spectrum. Therefore, KATRIN possesses a complex calibration and monitoring system to determine all systematics with the highest precision in situ, e.g. the source strength, the inelastic scattering of beta electrons in the tritium source, the retardation voltage and the work functions of the tritium source and the main spectrometer.

    Start-up and beyond

    After intense periods of commissioning during 2018, the tritium source activity was increased from its initial value of 0.5 GBq (which was used for the inauguration measurements) to 25 GBq (approximately 22% of nominal activity) in spring 2019. By April, the first KATRIN science run had begun and everything went like clockwork. The decisive source parameters – temperature, inlet pressure and tritium content – allowed excellent data to be taken, and the collaboration worked in several independent teams to analyse these data. The critical systematic uncertainties were determined both by Monte Carlo propagation and with the covariance-matrix method, and the analyses were also blinded so as not to generate bias. The excitement during the un-blinding process was huge within the KATRIN collaboration, which gathered for this special event, and relief spread when the result became known. The neutrino-mass square turned out to be compatible with zero within its uncertainty budget. The model fits the data very well (figure 3) and the fitted endpoint turned out to be compatible with the mass difference between 3He and tritium measured in Penning traps. The new results were presented at the international TAUP 2019 conference in Toyama, Japan, and have recently been published.

    Fig. 3. The beta-electron spectrum in the vicinity of its endpoint with 50 times enlarged error bars and a best-fit model (top) and fit residuals (bottom). Credit: CERN

    This first result shows that all aspects of the KATRIN experiment, from hardware to data-acquisition to analysis, works as expected. The statistical uncertainty of the first KATRIN result is already smaller by a factor of two compared to previous experiments and systematic uncertainties have gone down by a factor of six. A neutrino mass was not yet extracted with these first four weeks of data, but an upper limit for the neutrino mass of 1.1 eV (90% confidence) can be drawn, catapulting KATRIN directly to the top of the world of direct neutrino-mass experiments. In the mass region around 1 eV, the limit corresponds to the quasi-degenerated neutrino-mass range where the mass splittings implied by neutrino-oscillation experiments are negligible compared to the absolute masses.

    The neutrino-mass result from KATRIN is complementary to results obtained from searches for neutrinoless double beta decay, which are sensitive to the “coherent sum” mββ of all neutrino mass eigenstates contributing to the electron neutrino. Apart from additional phases that can lead to possible cancellations in this sum, the values of the nuclear matrix elements that need to be calculated to connect the neutrino mass mββ with the observable (the half-life) still possess uncertainties of a factor two. Therefore, the result from a direct neutrino-mass determination is more closely connected to results from cosmological data, which give (model-dependent) access to the neutrino-mass sum.

    A sizeable influence

    Currently, KATRIN is taking more data and has already increased the source activity by a factor of four to close to its design value. The background rate is still a challenge. Various measures, such as out-baking and using liquid-nitrogen cooled baffles in front of the getter pumps, have already yielded a background reduction by a factor 10, and more will be implemented in the next few years. For the final KATRIN sensitivity of 0.2 eV (90% confidence) on the absolute neutrino-mass scale, a total of 1000 days of data are required. With this sensitivity KATRIN will either find the neutrino mass or will set a stringent upper limit. The former would confront standard cosmology, while the latter would exclude quasi-degenerate neutrino masses and a sizeable influence of neutrinos on the formation of structure in the universe. This will be augmented by searches for physics beyond the Standard Model, such as for sterile neutrino admixtures with masses from the eV to the keV scale.

    Standard Model of Particle Physics

    Neutrino-oscillation results yield a lower limit for the effective electron-neutrino mass to manifest in direct neutrino-mass experiments of about 10 meV (50 meV) for normal (inverse) mass ordering. Therefore, many plans exist to cover this region in the future. At KATRIN, there is a strong R&D programme to upgrade the MAC-E filter principle from the current integral to a differential read-out, which will allow a factor-of-two improvement in sensitivity on the neutrino mass. New approaches to determine the absolute neutrino-mass scale are also being developed: Project 8, a radio-spectroscopy method to eventually be applied to an atomic tritium source; and the electron-capture experiments ECHo and HOLMES, which intend to deploy large arrays of cryogenic bolometers with the implanted isotope 163Ho. In parallel, the next generation of neutrinoless double beta decay experiments like LEGEND, CUPID or nEXO (as well as future xenon-based dark-matter experiments) aim to cover the full range of inverted neutrino-mass ordering. Finally, refined cosmological data should allow us to probe the same mass region (and beyond) within the next decades, while long-baseline neutrino-oscillation experiments, such as JUNO, DUNE and Hyper-Kamiokande, will probe the neutrino-mass ordering implemented in nature. As a result of this broad programme for the 2020s, the elusive neutrino should finally yield some of its secrets and inner properties beyond mixing.

    See the full article here .

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  • richardmitnick 4:47 pm on January 9, 2020 Permalink | Reply
    Tags: "Department of Energy picks New York over Virginia for site of new particle collider", , , , , , Particle Physics, ,   

    From BNL via Science Magazine: “Department of Energy picks New York over Virginia for site of new particle collider” 

    From Brookhaven National Lab


    Science Magazine

    Jan. 9, 2020
    Adrian Cho

    Nuclear physicists’ next dream machine will be built at Brookhaven National Laboratory in Upton, New York, officials with the Department of Energy (DOE) announced today. The Electron-Ion Collider (EIC) will smash a high-energy beam of electrons into one of protons to probe the mysterious innards of the proton. The machine will cost between $1.6 billion and $2.6 billion and should be up and running by 2030, said Paul Dabbar, DOE’s undersecretary for science, in a telephone press briefing.

    This schematic shows how the EIC will fit within the tunnel of the Relativistic Heavy Ion Collider (RHIC, background photo), reusing essential infrastructure and key components of RHIC.

    Electrons will collide with protons or larger atomic nuclei at the Electron-Ion Collider to produce dynamic 3-D snapshots of the building blocks of all visible matter.

    The EIC will allow nuclear physicists to track the arrangement of the quarks and gluons that make up the protons and neutrons of atomic nuclei.

    “It will be the first brand-new greenfield collider built in the country in decades,” Dabbar said. “The U.S. has been at the front end in nuclear physics since the end of the Second World War and this machine will enable the U.S. to stay at the front end for decades to come.”

    The site decision brings to a close the competition to host the machine. Physicists at DOE’s Thomas Jefferson National Accelerator Facility in Newport News, Virginia, had also hoped to build the EIC.

    Protons and neutrons make up the atomic nucleus, so the sort of work the EIC would do falls under the rubric of nuclear physics. Although they’re more common than dust, protons remain somewhat mysterious. Since the early 1970s, physicists have known that each proton consists of a trio of less massive particles called quarks. These bind to one another by exchanging other quantum particles called gluons.

    However, the detailed structure of the proton is far more complex. Thanks to the uncertainties inherent in quantum mechanics, its interior roils with countless gluons and quark-antiquark pairs that flit in and out of existence too quickly to be directly observed. And many of the proton’s properties—including its mass and spin—emerge from that sea of “virtual” particles. To determine how that happens, the EIC will use its electrons to probe the protons, colliding the two types of particles at unprecedented energies and in unparalleled numbers.

    Researchers at Jefferson lab already do similar work by firing their electron beam at targets rich with protons and neutrons. In 2017, researchers completed a $338 million upgrade to double the energy of the lab’s workhorse, the Continuous Electron Beam Accelerator Facility.

    Continuous Electron Beam Accelerator Facility

    With that electron accelerator in hand, Jefferson lab researchers had hoped to build the EIC by adding a new proton accelerator.

    Brookhaven researchers have studied a very different type of nuclear physics. Their Relativistic Heavy Ion Collider (RHIC) [below] collides nuclei such as gold and copper to produce fleeting puffs of an ultrahot plasma of free-flying quarks and gluons like the one that filled the universe in the split second after the big bang. The RHIC is a 3.8-kilometer-long ring consisting of two concentric and counter-circulating accelerators. Brookhaven researchers plan to make the EIC by using one of the RHIC’s rings to accelerate the protons and to add an electron accelerator to the complex.

    To decide which option to take, DOE officials convened an independent EIC site selection committee, Dabbar says. The committee weighed numerous factors, including the relative costs of the rival plans, he says. Proton accelerators are generally larger and more expensive than electron accelerators.

    The Jefferson lab won’t be left out in the cold, Dabbar says. Researchers there have critical expertise in, among other things, making the superconducting accelerating cavities that will be needed for the new collider. So, scientists there will participate in designing, building, and operating the new collider. “We certainly look forward to [the Jefferson lab] taking the lead in these areas,” Dabbar says.

    The site decision does not commit DOE to building the EIC. The project must still pass several milestones before researchers can being construction—including the approval of a detailed design, cost estimate, and construction schedule. That process can take a few years. However, the announcement does signal the end for the RHIC, which has run since 1999. To make way for the new collider, the RHIC will shut down for good in 2024, Dabbar said at the briefing.

    The decision on a machine still 10 years away reflects the relative good times for DOE science funding, Dabbar says. “We’ve been able to start on every major project that’s been on the books for years.” DOE’s science budget is up 31% since 2016—in spite of the fact that under President Donald Trump, the White House has tried to slash it every year.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

  • richardmitnick 3:46 pm on January 9, 2020 Permalink | Reply
    Tags: , , , , , Particle Physics, ,   

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

    Symmetry Mag
    From Symmetry<

    Diana Kwon

    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

    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 1:09 pm on January 9, 2020 Permalink | Reply
    Tags: "The CUORE Underground Experiment Narrows the Search for Rare Particle Process", , , CUORE experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) in Italy., , Matter vs Antimatter, Particle Physics   

    From Lawrence Berkeley National Lab: “The CUORE Underground Experiment Narrows the Search for Rare Particle Process” 

    Berkeley Logo

    From Lawrence Berkeley National Lab

    January 9, 2020

    Glenn Roberts Jr.
    (510) 486-5582

    New data yield one of the most sensitive probes to date of processes that may have seeded the matter vs. antimatter imbalance in the universe.

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

    Researchers work on the assembly of the CUORE experiment before it begins taking data. (Credit: CUORE Collaboration)

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

    In an underground laboratory deep beneath a mountain in Central Italy, an array of crystals, chilled to within a hair of absolute zero – the coldest possible temperature in the universe – has been steadily compiling one of the most precise measurements to date in pursuit of a rare particle process. If it is proven to exist, this process may well be the “smoking gun” of how matter was created in the universe.

    The experiment that is designed to seek out this process, called CUORE (Cryogenic Underground Observatory for Rare Events), is at Gran Sasso National Laboratories, part of the Italian National Institute for Nuclear Physics (INFN).

    The observation of this process, known as neutrinoless double-beta decay, would have profound implications for understanding the properties of ghostly, abundant particles called neutrinos that pass through most matter unaffected. U.S. Department of Energy-supported nuclear physicists play a leading scientific and technical role in this experiment.

    The latest results [https://arxiv.org/abs/1912.10966] represent more than a 2-year span of data collection – from April 2017 to July 2019. This data set, which is about four times larger than the initial results announced in October 2017 (see a related article), sets even more stringent limits on the theoretical ultra-rare process that CUORE is designed to seek out.

    Double-beta decay is a proven particle process in which two neutrons – uncharged particles in the nucleus, morph into two protons and emit two electrons and two antineutrinos – the antiparticles, or antimatter counterparts, to neutrinos.

    CUORE is designed to detect the signature of a theoretical neutrinoless double-beta decay process in which no antineutrinos are created. This is because they would erase each other in the decay process, proving that the neutrino is its own antiparticle, as the Italian scientist Ettore Majorana hypothesized in 1937.

    “We have now more than quadrupled the collected data, reaching one of the best sensitivities worldwide for the discovery of this rare particle process,” said Oliviero Cremonesi, senior researcher at INFN Milano Bicocca and spokesperson of the CUORE Collaboration.

    Yury Kolomensky, U.S. spokesperson for the CUORE collaboration and senior faculty scientist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), said, “The decay process in the CUORE crystals is a matter-creating process relevant to the Big Bang at the inception of our universe, and could help us to explain how matter won out over antimatter in its evolution.” Kolomensky is also a physics professor at UC Berkeley.

    Discovery of this neutrinoless process would mean that a neutrino and an antineutrino, which are both electrically neutral, are essentially the same particle (called a Majorana neutrino) and only differ in a mirroring property known as helicity. Helicity is somewhat analogous to a person being either left-handed or right-handed, and a Majorana neutrino could switch handedness – akin to an ambidextrous person.

    The CUORE detector array consists of 988 cube-shaped crystals made of a highly purified, natural form of tellurium dioxide that are stacked in 19 copper-cladded towers.

    The CUORE detector array during assembly. (Credit: Yura Suvorov)

    While no sign of neutrinoless double-beta decay is found in the data at this time, CUORE improved by a factor of two, compared to the previous results, the bound on the rate of this process in the nuclei of tellurium-130 atoms that are contained in the CUORE crystals. The interpretation of this result is a tighter bound on the allowed value of the neutrino mass in the Majorana hypothesis, which now extends below one-tenth of an electronvolt, at least 5 million times lighter than an electron.

    The results incorporate a sophisticated new algorithm that helps to amplify CUORE’s detected signals while cutting out unwanted background “noise.” The algorithm helps identify and reject signals caused by small energy deposits in the detectors, such as those left by some other, well-known particle decays. This could provide a cleaner signature of neutrinoless double-beta decay.

    The new algorithm would also allow CUORE to hunt for theoretical particles of dark matter known as WIMPs, or weakly interacting massive particles, in its nearly 1-ton detector.

    “This is the largest, most sensitive detector of its kind in the world,” said Thomas O’Donnell, professor of physics at Virginia Tech University and a member of the CUORE Physics Board that organized and coordinated the data analysis. “Each month we are accumulating as much data as some detectors get in a year.”

    CUORE’s latest results represent the largest data set collected by a particle detector that uses solid crystals, rather than the more common tank of liquid, in an effort to find this particle process. It is the first example of a solid-state detector with nearly a ton of mass.

    Solid-state detectors have the ability to very accurately measure the energy of particle decays. But it is challenging to scale up a solid-state detector to very large sizes when compared to a liquid-based detector.

    “We are delighted that we are now operating the detectors at close to 90% efficiency,” added Carlo Bucci, senior researcher at INFN’s Gran Sasso, who is the Italian spokesperson and technical coordinator of the experiment. “All of the work invested in the last two years to bring the system to this performance has paid off. Warming up and cooling back down takes several months, so we have to get it right each time.”

    The crystal array is extremely sensitive to a very slight and narrow energy signature that is predicted for the neutrinoless decay process. Chilling the array to below minus 459 degrees Fahrenheit makes the entire array, which weighs about 1,650 pounds, sensitive to an incredibly slight rise in temperature arising from a particle interaction with a detector crystal. The tellurium-130 in the crystals, which is the decaying component in the detector, accounts for about 450 pounds of that weight.

    This heightened sensitivity, which enables CUORE to look for signatures of dark matter particles – could possibly help to understand a periodic signal that a dark matter experiment called DAMA/LIBRA, installed at the same Gran Sasso site, has reported.

    DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) in Italy

    After CUORE’s 5-year run, a planned next-gen upgrade called CUPID will exchange the tellurium crystals with new crystals that will use a form of molybdenum with light-emitting properties. These crystals can produce both temperature-based and light-based signals that will further extend the sensitivity of the detector’s measurements.

    “It is an exciting time for neutrino physics,” said Claudia Tomei, a member of the CUORE Executive Board and a researcher at INFN Roma, “with numerous complementary experiments that will help us better understand the properties of neutrinos.”

    Cremonesi added, “We know we’ll learn something. We’re aiming for definitive measurements.”

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

    See the full article here .


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

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  • richardmitnick 10:57 am on January 9, 2020 Permalink | Reply
    Tags: "New open release allows theorists to explore LHC data in a new way", , , , , Particle Physics, , The first open release of full analysis likelihoods from an LHC experiment.   

    From CERN ATLAS: “New open release allows theorists to explore LHC data in a new way” 

    CERN/ATLAS detector

    CERN ATLAS Higgs Event

    CERN ATLAS another view Image Claudia Marcelloni ATLAS CERN


    9 January, 2020
    Katarina Anthony

    The ATLAS collaboration releases full analysis likelihoods, a first for an LHC experiment.

    Explore ATLAS open likelihoods on the HEPData platform. (Image: CERN)

    What if you could test a new theory against LHC data? Better yet, what if the expert knowledge needed to do this was captured in a convenient format? This tall order is now on its way from the ATLAS collaboration, with the first open release of full analysis likelihoods from an LHC experiment.

    “Likelihoods allow you to compute the probability that the data observed in a particular experiment match a specific model or theory,” explains Lukas Heinrich, CERN research fellow working for the ATLAS Experiment. “Effectively, they summarise every aspect of a particular analysis, from the detector settings, event selection, expected signal and background processes, to uncertainties and theoretical models.” Extraordinarily complex and critical to every analysis, likelihoods are one of the most valuable tools produced at the LHC experiments. Their public release will now enable theorists around the world to explore ATLAS data in a whole new way.

    The ATLAS open likelihoods are available on HEPData, an open-access repository for experimental particle physics data. The first open likelihoods released were for a search for supersymmetry in proton–proton collision events containing Higgs bosons, numerous jets of b-quarks and missing transverse momentum. “While ATLAS had published likelihood scans focused on the Higgs boson in 2013, those did not expose the full complexity of the measurements,” says Kyle Cranmer, Professor at New York University. “We hope this first release – which provides the full likelihoods in all their glory – will form a new communication bridge between theorists and experimentalists, enriching the discourse between the communities.”

    The search for new physics will benefit significantly from open likelihoods. “If you’re a theorist developing a new idea, your first question is likely: ‘Is my model already excluded by experiments at the LHC?’” says Giordon Stark, postdoctoral scholar at SCIPP, UC Santa Cruz. “Until now, there was no easy way to answer this.”

    Likelihoods are an essential link between theory and ATLAS data. (Image: K. Cranmer/ATLAS)

    “We plan to make the open release of likelihoods a regular part of our publication process, and have already made them available from a search for the direct production of tau slepton pairs,” says Laura Jeanty, ATLAS Supersymmetry working group convenor. “Over the coming months, we aim to collect feedback from theorists outside the collaboration to best understand how they are using this new resource to further refine future releases.”

    Read more on the ATLAS website.

    See the full article here .

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