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  • richardmitnick 12:46 pm on August 16, 2017 Permalink | Reply
    Tags: , As time passes and we still haven’t detected WIMPs, , , , Can Radio Telescopes Find Axions?, , , Galactic halo model, Magnetic fields can change axions to and from photons, Particle Physics, ,   

    From AAS NOVA: “Can Radio Telescopes Find Axions?” 

    AASNOVA

    American Astronomical Society

    16 August 2017
    Susanna Kohler

    1
    A simulation showing the distribution of dark matter in the universe. [AMNH]

    Dark matter halo Image credit: Virgo consortium / A. Amblard / ESA

    In the search for dark matter, the most commonly accepted candidates are invisible, massive particles commonly referred to as WIMPs. But as time passes and we still haven’t detected WIMPs, alternative scenarios are becoming more and more appealing. Prime among these is the idea of axions.

    2
    The Italian PVLAS is an example of a laboratory experiment that attempted to confirm the existence of axions. [PVLAS]

    A Bizarre Particle

    Axions are a type of particle first proposed in the late 1970s. These theorized particles arose from a new symmetry introduced to solve ongoing problems with the standard model for particle physics, and they were initially predicted to have more than a keV in mass. For this reason, their existence was expected to be quickly confirmed by particle-detector experiments — yet no detections were made.

    Today, after many unsuccessful searches, experiments and theory tell us that if axions exist, their masses must lie between 10-6–10-3 eV. This is minuscule — an electron’s mass is around 500,000 eV, and even neutrinos are on the scale of a tenth of an eV!

    But enough of anything, even something very low-mass, can weigh a lot. If they are real, then axions were likely created in abundance during the Big Bang — and unlike heavier particles, they can’t decay into anything lighter, so we would expect them all to still be around today. Our universe could therefore be filled with invisible axions, potentially providing an explanation for dark matter in the form of many, many tiny particles.

    4
    Artist’s impression of the central core of proposed Square Kilometer Array antennas. [SKA/Swinburne Astronomy Productions]

    How Do We Find Them?

    Axions barely interact with ordinary matter and they have no electric charge. One of the few ways we can detect them is with magnetic fields: magnetic fields can change axions to and from photons.

    While many studies have focused on attempting to detect axions in laboratory experiments, astronomy provides an alternative: we can search for cosmological axions. Now scientists Katharine Kelley and Peter Quinn at ICRAR, University of Western Australia, have explored how we might use next-generation radio telescopes to search for photons that were created by axions interacting with the magnetic fields of our galaxy.

    5
    Potential axion coupling strengths vs. mass (click for a closer look). The axion mass is thought to lie between a µeV and a meV; two theoretical models are shown with dashed lines. The plot shows the sensitivity of the upcoming SKA and its precursors, ASKAP and MEERKAT. [Kelley&Quinn 2017]

    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

    Hope for Next-Gen Telescopes

    By using a simple galactic halo model and reasonable assumptions for the central galactic magnetic field — even taking into account the time dependence of the field — Kelley and Quinn estimate the radio-frequency power density that we would observe at Earth from axions being converted to photons within the Milky Way’s magnetic field.

    The authors then compare this signature to the detection capabilities of upcoming radio telescope arrays. They show that the upcoming Square Kilometer Array and its precursors should have the capability to detect signs of axions across large parts of parameter space.

    Kelley and Quinn conclude that there’s good cause for optimism about future radio telescopes’ ability to detect axions. And if we did succeed in making a detection, it would be a triumph for both particle physics and astrophysics, finally providing an explanation for the universe’s dark matter.

    Citation

    Katharine Kelley and P. J. Quinn 2017 ApJL 845 L4. doi:10.3847/2041-8213/aa808d

    Related Journal Articles
    See the full article for further references with links.

    See the full article here .

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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 11:32 am on August 14, 2017 Permalink | Reply
    Tags: , ATLAS sees first direct evidence of light-by-light scattering at high energy, , , , , Particle Physics   

    From ATLAS at CERN: “ATLAS sees first direct evidence of light-by-light scattering at high energy” 

    CERN ATLAS Higgs Event

    CERN/ATLAS
    ATLAS

    14th August 2017
    Katarina Anthony

    1
    A light-by-light scattering candidate event measured in the ATLAS detector. (Image: ATLAS Collaboration/CERN).

    Physicists from the ATLAS experiment at CERN have found the first direct evidence of high energy light-by-light scattering, a very rare process in which two photons – particles of light – interact and change direction. The result, published today in Nature Physics , confirms one of the oldest predictions of quantum electrodynamics (QED).

    “This is a milestone result: the first direct evidence of light interacting with itself at high energy,” says Dan Tovey (University of Sheffield), ATLAS Physics Coordinator. “This phenomenon is impossible in classical theories of electromagnetism; hence this result provides a sensitive test of our understanding of QED, the quantum theory of electromagnetism.”

    Direct evidence for light-by-light scattering at high energy had proven elusive for decades – until the Large Hadron Collider’s second run began in 2015. As the accelerator collided lead ions at unprecedented collision rates, obtaining evidence for light-by-light scattering became a real possibility. “This measurement has been of great interest to the heavy-ion and high-energy physics communities for several years, as calculations from several groups showed that we might achieve a significant signal by studying lead-ion collisions in Run 2,” says Peter Steinberg (Brookhaven National Laboratory), ATLAS Heavy Ion Physics Group Convener.

    Heavy-ion collisions provide a uniquely clean environment to study light-by-light scattering. As bunches of lead ions are accelerated, an enormous flux of surrounding photons is generated. When ions meet at the centre of the ATLAS detector, very few collide, yet their surrounding photons can interact and scatter off one another. These interactions are known as ‘ultra-peripheral collisions’.

    Studying more than 4 billion events taken in 2015, the ATLAS collaboration found 13 candidates for light-by-light scattering. This result has a significance of 4.4 standard deviations, allowing the ATLAS collaboration to report the first direct evidence of this phenomenon at high energy.

    “Finding evidence of this rare signature required the development of a sensitive new ‘trigger’ for the ATLAS detector,” says Steinberg. “The resulting signature — two photons in an otherwise empty detector — is almost the diametric opposite of the tremendously complicated events typically expected from lead nuclei collisions. The new trigger’s success in selecting these events demonstrates the power and flexibility of the system, as well as the skill and expertise of the analysis and trigger groups who designed and developed it.”

    ATLAS physicists will continue to study light-by-light scattering during the upcoming LHC heavy-ion run, scheduled for 2018. More data will further improve the precision of the result and may open a new window to studies of new physics. In addition, the study of ultra-peripheral collisions should play a greater role in the LHC heavy-ion programme, as collision rates further increase in Run 3 and beyond.

    See the full article here .

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

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    CERN Courier

    QuantumDiaries


    Quantum Diaries

     
  • richardmitnick 12:16 pm on August 12, 2017 Permalink | Reply
    Tags: ALPIDE chip, , , Desk cosmic ray detector, Particle Physics, , The ALPIDE chip is a CMOS monolithic active pixel sensor   

    From ALICE at CERN: “A desk cosmic ray detector for schools using the ALPIDE chip” 

    CERN
    CERN New Masthead

    11 August 2017
    Virginia Greco

    An educational and outreach project conceived by the ALICE ITS team is now moving forward rapidly thanks to Matthew Aquilina, who has joined the collaboration as a summer student, and his supervisors Magnus Mager and Felix Reidt.

    1
    Magnus Mager (left) and Matthew Aquilina (right). In the center, a prototype of compact cosmic ray detector based on the ALPIDE chip. [Credits: Virginia Greco]

    Would you like to have your own cheap and compact cosmic ray detector, sitting right on your desk? It sounds much like a nerdy fantasy, but indeed such a device can be realized and become a very useful educational and outreach tool.

    This was the idea inspiring the ALICE ITS team at CERN, who decided to use the pixel sensor chip (ALPIDE) to build a small and easy-to-operate cosmic ray detector. The project is now taking off thanks to the involvement of Matthew Aquilina – a summer student from Malta who joined the group at the end of June – and his supervisors Magnus Mager and Felix Reidt.

    The ALPIDE chip is a CMOS monolithic active pixel sensor being developed for the upgrade of the ITS of the ALICE experiment and characterized by very high detection efficiency.

    Some spare ALPIDE chips could be diverted to this pedagogical project, in which they are used to detect muons and electrons from cosmic rays. By making a stack of up to four chips, connected one-to-one, it is possible to reconstruct the trajectory of a particle crossing them. Considering an average rate of one cosmic ray per square centimeter per minute, with its active area of 1.4cm x 3cm, the ALPIDE chip registers a hit every few seconds. Because of the acceptance limitation in terms of solid angle due to the setup, the reconstruction rate is around 1 cosmic ray track per minute.

    “The ALPIDE chip is very good for this application since it has very low noise,” explains Magnus. “In addition, it has a multiple-event buffer that allow acquiring new data while we are reading out the previous, so essentially it is dead-time free.”

    2
    In order to target educational and outreach activities, a dedicated, cost-effective, and easy to use readout system was devised. It was decided to interface the chip to an Arduino microprocessor board, which is largely used for being very versatile and easy to program.

    The setup of the compact cosmic ray detector, thus, includes an Arduino card and up to four boards hosting each an ALPIDE chip, one on top of the other. “Programming the Arduino microprocessor to communicate with the chips turned out to be fairly easy,” Magnus comments, “but we still needed an interface to allow people having no specific technical expertise to operate the system.”

    Here is when Matthew came in. His main task, in fact, is to develop a user-friendly interface to control the system, with the aim to make it ‘plug and play’. He is employing the Unity platform, which is free software meant for developing 3D games but can also be used to make interfaces with 3D objects and operation menus. In this specific case, the user will be able to see on the screen the four detector planes, the pixel detectors on them and, when a cosmic ray crosses their active area, the corresponding hit in each plane. The work is still in progress but is moving forward rapidly.

    “When I started, first of all I had to study the Arduino-ALPIDE communication protocol, which meant going through the 110-page ALPIDE manual,” Matthew explains; “during the second week, I interfaced the microprocessor with Unity and then I started developing the user-friendly interface”. Indeed, he was chosen by Magnus and his colleagues among many candidates for his previous experience with the Unity software, which he had gained by developing a 3D game with it.

    A potential future development for the project is to allow data saving in exportable file formats to be read by other programs, so that some data analysis – such as angular distribution of the cosmic rays, day/night dependence and season dependence – could be performed.

    Once the user-friendly interface is done, it will be time to ‘advertise’ the project and make the system available to teachers and students. Some channels to take into consideration are the CERN teacher programmes and the CERN S’Cool Lab. “This device can be useful both for computer science and physics classes,” adds Magnus, “because students can learn about cosmic rays and detectors as well as how to program Arduino to communicate with a custom chip.”

    It can also be used for outreach purposes in some special event, such as the CERN open days.

    Matthew, on his side, is already profiting of this project, since he is enhancing his programming skills and is learning about physics and electronics. At the fourth year of his undergraduate engineering course at the University of Malta, Matthew applied to the CERN summer student programme attracted by the perspective of spending some time at CERN and because he was willing to have an experience outside his country.

    “I think I will continue my studies enrolling in a Master’s and a PhD programme, but I am not sure about the topic yet,” he declares. “Actually, at high-school I studied mainly chemistry and biology, then at the University I switched to engineering. I think I will continue with something that incorporates programming and electronics, such as robotics”.

    See the full article here .

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    Meet CERN in a variety of places:


    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS
    ATLAS
    CERN/ATLAS detector

    ALICE
    CERN ALICE New

    CMS
    CERN/CMS Detector

    LHCb

    CERN/LHCb

    LHC

    CERN/LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles


    Quantum Diaries

     
  • richardmitnick 7:58 am on August 10, 2017 Permalink | Reply
    Tags: , , , Particle Physics, , ,   

    From ScienceNews: “Neutrino experiment may hint at why matter rules the universe” 

    ScienceNews bloc

    ScienceNews

    1
    NEUTRINO CLUES The T2K experiment found clues that neutrinos may behave differently than their antimatter partners. In a possible sighting of an electron neutrino at the Super-Kamiokande detector in Hida, Japan (shown), colored spots represent sensors that observed light from the interacting neutrino. Kamioka Observatory/ICRR/The University of Tokyo

    A new study hints that neutrinos might behave differently than their antimatter counterparts. The result amplifies scientists’ suspicions that the lightweight elementary particles could help explain why the universe has much more matter than antimatter.

    In the Big Bang, 13.8 billion years ago, matter and antimatter were created in equal amounts. To tip that balance to the universe’s current, matter-dominated state, matter and antimatter must behave differently, a concept known as CP, or “charge parity,” violation.

    In neutrinos, which come in three types — electron, muon and tau — CP violation can be measured by observing how neutrinos oscillate, or change from one type to another. Researchers with the T2K experiment found that muon neutrinos morphed into electron neutrinos more often than expected, while muon antineutrinos became electron antineutrinos less often. That suggests that the neutrinos were violating CP, the researchers concluded August 4 at a colloquium at the High Energy Accelerator Research Organization, KEK, in Tsukuba, Japan.

    T2K scientists had previously presented a weaker hint [Physical Review Letters]of CP violation. The new result is based on about twice as much data, but the evidence is still not definitive. In physicist parlance, it is a “two sigma” measurement, an indicator of how statistically strong the evidence is. Physicists usually require five sigma to claim a discovery.

    Even three sigma is still far away — T2K could reach that milestone by 2026. A future experiment, DUNE, now under construction at the Sanford Underground Research Laboratory in Lead, S.D., may reach five sigma.

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    It is worth being patient, says physicist Chang Kee Jung of Stony Brook University in New York, who is a member of the T2K collaboration. “We are dealing with really profound problems.”

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

    Published since 1922, the biweekly print publication reaches about 90,000 dedicated subscribers and is available via the Science News app on Android, Apple and Kindle Fire devices. Updated continuously online, the Science News website attracted over 12 million unique online viewers in 2016.

    Science News is published by the Society for Science & the Public, a nonprofit 501(c) (3) organization dedicated to the public engagement in scientific research and education.

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  • richardmitnick 11:02 am on August 7, 2017 Permalink | Reply
    Tags: , , , , , , Particle Physics   

    From BNL: “MicroBooNE Produces Clearest Images of Neutrino Interactions Yet” 

    Brookhaven Lab

    August 7, 2017
    Kelsey Harper
    kharper@bnl.gov

    With updates to its electronics, the state-of-the-art neutrino detector now boasts impressive “signal to noise” sensitivity.

    1
    A 3D reconstruction of various particles, including neutrinos, interacting with the argon atoms inside MicroBooNE’s time projection chamber (TPC). This reconstruction is based off of when and where electrons produced by such interactions hit the plane of wires at one end of the TPC.

    FNAL/MicrobooNE

    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab).

    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab). With implementation of sophisticated noise-filtering software and updates to the detector hardware, the MicroBooNE collaboration has produced new clean images that make it easier for researchers to spot and study different types of neutrinos. A paper published in the Journal of Instrumentation illustrates the electronic challenges and solutions that led to this advance.

    “These innovations will naturally be included in the next generation of neutrino detector design,” said Brookhaven physicist Xin Qian, the leader of Brookhaven’s MicroBooNE physics group.

    The next generation is a big deal, literally: four 17,000-ton neutrino detectors (compared to MicroBooNE’s “small” 170-ton detector) are planned for a future Deep Underground Neutrino Experiment (DUNE).

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    This massive project will attempt to solve some of the biggest mysteries about neutrinos and their role in our universe.

    Tracking elusive particles

    Trillions of neutrinos—abundant yet elusive particles created in the nuclear reactions powering stars—stream from our sun to Earth every second. But because these particles so rarely interact with matter (which is why we don’t feel them passing through us), the detectors built to spot them must be extremely large and sensitive. To study neutrinos, scientists often also turn to more intense and easily understood sources of these particles: nuclear reactors and particle accelerators. The MicroBooNE collaboration studies neutrinos generated by the Booster proton accelerator at Fermilab, and collects detailed images of their interactions with a detector called a liquid-argon time projection chamber (LArTPC).

    3
    MicroBooNE’s time projection chamber—where the neutrino interactions take place—during assembly at Fermilab. The chamber measures ten meters long and two and a half meters high. Photo credit: Fermilab

    Although a ‘time projection chamber’ may sound like something from a Michael Crichton novel, it’s a very real technology that has transformed neutrino physics. It’s one of the few types of detectors that can see most of what happens when a neutrino interacts inside.

    Neutrinos come in three different “flavors”—electron, muon, and tau. As these neutrinos sail through the LArTPC’s school bus-sized tank of argon, kept liquid at a biting -303 degrees Fahrenheit, they occasionally interact with one of the argon atoms. This interaction produces charged and neutral particles, with a charged particle sometimes corresponding to the type of neutrino involved. The charged particles shoot through the bath, kicking electrons off the argon atoms they pass. These electrons get caught in the tank’s strong electric field and zip toward one end, eventually striking an array of wires. Based on the time and placement of each signal generated when an electron strikes a wire, scientists can figure out where the neutrino collision took place and what it looked like, allowing them to determine the type and energy of the neutrino detected.

    Trouble arises, however, when the little currents produced by the kicked-off electrons are muffled by electronic “noise.” Much like static on a radio, noise can drown out the signals of a neutrino collision, making the reconstructed paths blurry and difficult to analyze. According to Jyoti Joshi, a Brookhaven Lab post-doctoral fellow and the leader of the MicroBooNE detector physics working group, the challenge with LArTPC electronics is that “the signal we’re dealing with is so small that we need a very, very sensitive detector to amplify the signal so we can see it. But then, of course, you amplify anything, including noise.”

    4
    Brookhaven Lab physicist Hucheng Chen holding a replica of one of the 50 cold electronics boards installed in MicroBooNE. He is standing next to a mock-up of one of MicroBooNE’s 11 signal feedthroughs—the part of the detector where electronic signals from the cold electronics of the time projection chamber are carried to the warm electronics outside the cryostat.

    To try to minimize noise, MicroBooNE researchers worked with the engineers and scientists at Fermilab and in Brookhaven Lab’s Instrumentation Division who had pioneered the development of “cold electronics” for the experiment. Placing the electronics inside the detector tank reduces noise by shortening the path each signal has to travel before getting amplified. But because the tank is filled with liquid argon, these electronics had to be designed to thrive at temperatures hundreds of degrees below zero, long past the range where conventional electronics, like those in your smartphone, can function.

    The researchers expected the cold electronics installed at MicroBooNE to produce relatively clean signals and a good picture of the neutrino collisions. But “there are always some surprises,” said Mary Bishai, a senior physicist at Brookhaven Lab. “We had all this excess noise, and at the beginning people blamed the newest technology, the cold electronics.”

    After a year of collecting data, the researchers had enough information to pinpoint three sources of excess noise.

    “The noise was nearly all from the conventional electronics outside the argon tank,” said Mike Mooney, a Brookhaven Lab post-doctoral fellow and a key contributor in the effort to identify sources of noise.

    Most of the noise came from the external power supply for the electronics inside the bath, and from small fluctuations in the high voltage that creates the tank’s electric field. The third and least significant source of noise was an unusual burst that appeared only at a certain frequency, but the team has yet to determine where this final source comes from.

    The collaboration initially reduced the excess noise by developing a software program to sift out the desired electron signals. This initial solution allowed them to collect higher-quality data while addressing the actual sources of noise. “We demonstrated that software could remove certain types of noise from the data without losing the very small signals we want to see” said Brian Kirby, the BNL post-doc leading the evaluation of the software fix.

    5
    A comparison of particle interaction signals before and after MicroBooNE researchers removed the excess noise.

    With the software in place, the researchers could make the necessary changes to the detector’s hardware. They tackled the power supply noise by replacing the part that, just like your laptop charger, converts a higher voltage to a stable lower voltage that the cold electronics require. To combat the noise associated with generating the tank’s electric field, the researchers added a filter that would stabilize the high voltage. They eliminated more than eighty percent of the original noise with these hardware changes alone, and reduced it even further by then reapplying the software filters.

    The reconstructed neutrino paths are now sharply clear, like the burst of a small firework that was previously obscured by fog. These clean tracks are absolutely vital as the MicroBooNE team is implementing pattern recognition software to “train” a computer to pick out different types of neutrino collisions.

    “This is a really big deal in terms of pushing the field forward,” says Qian. “The lessons we learned will feed back to the next generation of technology development. For this kind of technology, there’s no way we can do it ‘just right’ the first time. We need to try it and improve it, try it and improve it.”

    The MicroBooNE collaboration will continue doing just that, trying and improving, as it lays the groundwork for DUNE, the biggest neutrino experiment ever attempted.

    Brookhaven’s work on MicroBooNE was funded by the DOE Office of Science (HEP) and the National Science Foundation.

    See the full article here .

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    BNL Campus

    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.
    i1

     
  • richardmitnick 3:30 pm on August 4, 2017 Permalink | Reply
    Tags: , , , , , , Particle Physics, ,   

    From Symmetry: “The birth of a black hole, live” 09/09/15 

    Symmetry Mag

    Symmetry

    09/09/15 [this is old, but a lot of sites are featuring it again.]
    Lauren Biron

    1
    NASA/CXC/M.Weiss

    Scientists hope to use neutrino experiments to watch a black hole form.

    Black holes fascinate us. We easily conjure up images of them swallowing spaceships, but we know very little about these strange objects. In fact, we’ve never even seen a black hole form. Scientists on neutrino experiments such as the upcoming Deep Underground Neutrino Experiment hope to change that.

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    “You’ve got to be a bit lucky,” says Mark Thomson, DUNE co-spokesperson. “But it would be one of the major discoveries in science. It would be absolutely incredible.”

    Black holes are sometimes born when a massive star, typically more than eight times the mass of our own sun, collapses. But there are a lot of questions about what exactly happens during the process: How often do these collapsing stars give rise to black holes? When in the collapse does the black hole actually develop?

    What scientists do know is that deep in the dense core of the star, protons and electrons are squeezed together to form neutrons, sending ghostly particles called neutrinos streaming out. Matter falls inward. In the textbook case, matter rebounds and erupts, leaving a neutron star. But sometimes, the supernova fails, and there’s no explosion; instead, a black hole is born.

    DUNE’s gigantic detectors, filled with liquid argon, will sit a mile below the surface in a repurposed goldmine. While much of their time will be spent looking for neutrinos sent from Fermi National Accelerator Laboratory 800 miles away, the detectors will also have the rare ability to pick up a core collapse in our Milky Way galaxy – whether or not that leads to a new black hole.

    The only supernova ever recorded by neutrino detectors occurred in in 1987, when scientists saw a total of 19 neutrinos. Scientists still don’t know if that supernova formed a black hole or a neutron star—there simply wasn’t enough data. Thomson says that if a supernova goes off nearby, DUNE could see up to 10,000 neutrinos.

    DUNE will look for a particular signature in the neutrinos picked up by the detector. It’s predicted that a black hole will form relatively early in a supernova. Neutrinos will be able to leave the collapse in great numbers until the black hole emerges, trapping everything—including light and neutrinos—in its grasp. In data terms, that means you’d get a big burst of neutrinos with a sudden cutoff.

    Neutrinos come in three types, called flavors: electron, muon and tau. When a star explodes, it emits all the various types of neutrinos, as well as their antiparticles.

    They’re hard to catch. These neutrinos arrive with 100 times less energy than those arriving from an accelerator for experiments, which makes them less likely to interact in a detector.

    Most of the currently running, large particle detectors capable of seeing supernova neutrinos are best at detecting electron antineutrinos—and not great at detecting their matter equivalents, electron neutrinos.

    “It would be a tragedy to not be ready to detect the neutrinos in full enough detail to answer key questions,” says John Beacom, director of the Center for Cosmology and Astroparticle Physics at The Ohio State University.

    Luckily, DUNE is unique. “The only one that is sensitive to a huge slug of electron neutrinos is DUNE, and that’s a function of using argon [as the detector fluid],” says Kate Scholberg, professor of physics at Duke University.

    It will take more than just DUNE to get the whole picture, though. Getting an entire suite of large, powerful detectors of different types up and running is the best way to figure out the lives of black holes, Beacom says.

    There is a big scintillator detector, JUNO, in the works in China, and plans for a huge water-based detector, Hyper-K, in Japan.

    JUNO Neutrino detector, at Kaiping, Jiangmen in Southern China

    Hyper-Kamiokande, a neutrino physics laboratory located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

    Gravitational wave detectors such as LIGO could pick up additional information about the density of matter and what’s happening in the collapse.


    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-Zib

    ESA/eLISA the future of gravitational wave research

    “My dream is to have a supernova with JUNO, Hyper-K and DUNE all online,” Scholberg says. “It would certainly make my decade.”

    The rate at which neutrinos arrive after a supernova will tell scientists about what’s happening at the center of a core collapse—but it will also provide information about the mysterious neutrino, including how they interact with each other and potential insights as to how much the tiny particles actually weigh.

    Within the next three years, the rapidly growing DUNE collaboration will build and begin testing a prototype of the 40,000-ton liquid argon detector. This 400-ton version will be the second-largest liquid-argon experiment ever built to date. It is scheduled for testing at CERN starting in 2018.

    DUNE is scheduled to start installing the first of its four detectors in the Sanford Underground Research Facility in 2021.

    See the full article here .

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  • richardmitnick 12:20 pm on August 4, 2017 Permalink | Reply
    Tags: , , , , Particle Physics,   

    From CERN ALPHA: “The ALPHA experiment explores the secrets of antimatter” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    3 Aug 2017
    Stefania Pandolfi

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    Alpha Experiment (Image: Maximilien Brice/CERN)

    In a paper published today in Nature, the ALPHA experiment at CERN’s Antiproton Decelerator reports the first observation of the hyperfine structure of antihydrogen, the antimatter counterpart of hydrogen. These findings point the way to ever more detailed analyses of the structure of antihydrogen and could help understand any differences between matter and antimatter.

    The researchers conducted spectroscopy measurements on homemade antihydrogen atoms, which drive transitions between different energy states of the anti-atoms. They could in this way improve previous measurements by identifying and measuring two spectral lines of antihydrogen. Spectroscopy is a way to probe the internal structure of atoms by studying their interaction with electromagnetic radiation.

    In 2012, the ALPHA experiment demonstrated for the first time the technical ability to measure the internal structure of atoms of antimatter. In 2016, the team reported the first observation of an optical transition of antihydrogen. By exposing antihydrogen atoms to microwaves at a precise frequency, they have now induced hyperfine transitions and refined their measurements. The team were able to measure two spectral lines for antihydrogen, and observe no difference compared to the equivalent spectral lines for hydrogen, within experimental limits.

    “Spectroscopy is a very important tool in all areas of physics. We are now entering a new era as we extend spectroscopy to antimatter,” said Jeffrey Hangst, Spokesperson for the ALPHA experiment. “With our unique techniques, we are now able to observe the detailed structure of antimatter atoms in hours rather than weeks, something we could not even imagine a few years ago.”

    With their trapping techniques, ALPHA are now able to trap a significant number of antiatoms – up to 74 at a time – thereby facilitating precision measurements. With this new result, the ALPHA collaboration has clearly demonstrated the maturity of its techniques for probing the properties of antimatter atoms.

    The rapid progress of CERN’s experiments at the unique Antiproton Decelerator facility is very promising for ever more precise measurements to be carried out in the near future.

    CERN Antiproton Decelerator

    See the full article here.

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  • richardmitnick 11:35 am on August 4, 2017 Permalink | Reply
    Tags: 'Perfect Liquid' Quark-Gluon Plasma is the Most Vortical Fluid, , , , New record for "vorticity", Particle Physics, , STAR detector's Time Project Chamber   

    From BNL: “‘Perfect Liquid’ Quark-Gluon Plasma is the Most Vortical Fluid” 

    Brookhaven Lab

    August 2, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer,
    genzer@bnl.gov
    (631) 344-3174

    Swirling soup of matter’s fundamental building blocks spins ten billion trillion times faster than the most powerful tornado, setting new record for “vorticity”.

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    Ohio State University graduate student Isaac Upsal helped lead the analysis of results from the STAR detector that revealed a “vorticity” record for the quark-gluon plasma created in collisions at the Relativistic Heavy Ion Collider (RHIC).

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    Particle collisions recreating the quark-gluon plasma (QGP) that filled the early universe reveal that droplets of this primordial soup swirl far faster than any other fluid. The new analysis of data from the Relativistic Heavy Ion Collider (RHIC) — a U.S. Department of Energy Office of Science User Facility for nuclear physics research at Brookhaven National Laboratory — shows that the “vorticity” of the QGP surpasses the whirling fluid dynamics of super-cell tornado cores and Jupiter’s Great Red Spot by many orders of magnitude, and even beats out the fastest spin record held by nanodroplets of superfluid helium.

    The results, just published in Nature, add a new record to the list of remarkable properties ascribed to the quark-gluon plasma. This soup made of matter’s fundamental building blocks — quarks and gluons — has a temperature hundreds of thousands of times hotter than the center of the sun and an ultralow viscosity, or resistance to flow, leading physicists to describe it as “nearly perfect.” By studying these properties and the factors that control them, scientists hope to unlock the secrets of the strongest and most poorly understood force in nature — the one responsible for binding quarks and gluons into the protons and neutrons that form most of the visible matter in the universe today.

    Specifically, the results on vorticity, or swirling fluid motion, will help scientists sort among different theoretical descriptions of the plasma. And with more data, it may give them a way to measure the strength of the plasma’s magnetic field — an essential variable for exploring other interesting physics phenomena.

    “Up until now, the big story in characterizing the QGP is that it’s a hot fluid that expands explosively and flows easily,” said Michael Lisa, a physicist from Ohio State University (OSU) and a member of RHIC’s STAR collaboration. “But we want to understand this fluid at a much finer level. Does it thermalize, or reach equilibrium, quickly enough to form vortices in the fluid itself? And if so, how does the fluid respond to the extreme vorticity?” The new analysis, which was led by Lisa and OSU graduate student Isaac Upsal, gives STAR a way to get at those finer details.

    3
    Telltale signs of a lambda hyperon (Λ) decaying into a proton (p) and a pion (π-) as tracked by the Time Projection Chamber of the STAR detector. Because the proton comes out nearly aligned with the hyperon’s spin direction, tracking where these “daughter” protons strike the detector can be a stand-in for tracking how the hyperons’ spins are aligned.

    Aligning spins

    “The theory is that if I have a fluid with vorticity — a whirling substructure — it tends to align the spins of the particles it emits in the same direction as the whirls,” Lisa said. And, while there can be many small whirlpools within the QGP all pointing in random directions, on average their spins should align with what’s known as the angular momentum of the system — a rotation of the system generated by the colliding particles as they speed past one another at nearly the speed of light.

    To track the spinning particles and the angular momentum, STAR physicists correlated simultaneous measurements at two different detector components. The first, known as the Beam-Beam Counters, sit at the front and rear ends of the house-size STAR detector, catching subtle deflections in the paths of colliding particles as they pass by one another. The size and direction of the deflection tells the physicists how much angular momentum there is and which way it is pointing for each collision event.

    Meanwhile, STAR’s Time Project Chamber, a gas-filled chamber that surrounds the collision zone, tracks the paths of hundreds or even thousands of particles that come out perpendicular to the center of the collisions.

    “We’re specifically looking for signs of Lambda hyperons, spinning particles that decay into a proton and a pion that we measure in the Time Projection Chamber,” said Ernst Sichtermann, a deputy STAR spokesperson and senior scientist at DOE’s Lawrence Berkeley National Laboratory. Because the proton comes out nearly aligned with the hyperon’s spin direction, tracking where these “daughter” protons strike the detector can be a stand-in for tracking how the hyperons’ spins are aligned.

    “We are looking for some systematic preference for the direction of these daughter protons aligned with the angular momentum we measure in the Beam-Beam Counters,” Upsal said. “The magnitude of that preference tells us the degree of vorticity — the average rate of swirling — of the QGP.”

    4
    Tracking particle spins reveals that the quark-gluon plasma created at the Relativistic Heavy Ion Collider is more swirly than the cores of super-cell tornados, Jupiter’s Great Red Spot, or any other fluid!

    Super spin

    The results reveal that RHIC collisions create the most vortical fluid ever, a QGP spinning faster than a speeding tornado, more powerful than the fastest spinning fluid on record. “So the most ideal fluid with the smallest viscosity also has the most vorticity,” Lisa said.

    This kind of makes sense, because low viscosity in the QGP allows the vorticity to persist, Lisa said. “Viscosity destroys whirls. With QGP, if you set it spinning, it tends to keep on spinning.”

    The data are also in the ballpark of what different theories predicted for QGP vorticity. “Different theories predict different amounts, depending on what parameters they include, so our results will help us sort through those theories and determine which factors are most relevant,” said Sergei Voloshin, a STAR collaborator from Wayne State University. “But most of the theoretical predications were too low,” he added. “Our measurements show that the QGP is even more vortical than predicted.”

    This discovery was made during the Beam Energy Scan program, which exploits RHIC’s unique ability to systematically vary the energy of collisions over a range in which other particularly interesting phenomena have been observed. In fact, theories suggest that this may be the optimal range for the discovery and subsequent study of the vorticity-induced spin alignment, since the effect is expected to diminish at higher energy.

    Increasing the numbers of Lambda hyperons tracked in future collisions at RHIC will improve the STAR scientists’ ability to use these measurements to calculate the strength of the magnetic field generated in RHIC collisions. The strength of magnetism influences the movement of charged particles as they are created and emerge from RHIC collisions, so measuring its strength is important to fully characterize the QGP, including how it separates differently charged particles.

    “Theory predicts that the magnetic field created in heavy ion experiments is much higher than any other magnetic field in the universe,” Lisa said. At the very least, being able to measure it accurately may nab another record for QGP.

    Research at RHIC and with the STAR detector is funded primarily by the DOE Office of Science.

    See the full article here .

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    BNL Campus

    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.
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  • richardmitnick 3:17 pm on August 3, 2017 Permalink | Reply
    Tags: , COHERENT collaboration, Coherent scattering, Neutrino interaction process, ORNL Spallation Neutron Source, Particle Physics, , , Sandia-developed neutron scatter camera   

    From Sandia: “World’s smallest neutrino detector finds big physics fingerprint” 


    Sandia Lab

    August 3, 2017

    Sandia part of COHERENT experiment to measure coherent elastic neutrino-nucleus scattering

    Sandia National Laboratories researchers have helped solve a mystery that has plagued physicists for 43 years. Using the world’s smallest neutrino detector, the Sandia team was among a collaboration of 80 researchers from 19 institutions and four nations that discovered compelling evidence for a neutrino interaction process. The breakthrough paves the way for additional discoveries in neutrino behavior and the miniaturization of future neutrino detectors.

    1
    Sandia National Laboratories researchers David Reyna, left, and Belkis Cabrera-Palmer were instrumental in the COHERENT collaboration. (Photo by Michael Padilla)

    The COHERENT project was led by the Department of Energy’s Oak Ridge National Laboratory or ORNL. The research was performed at ORNL’s Spallation Neutron Source (SNS) and has been published in the journal Science titled Observation of Coherent Elastic Neutrino-Nucleus Scattering.

    ORNL Spallation Neutron Source

    The research team was the first to detect and characterize coherent elastic scattering of neutrinos off nuclei. This long-sought confirmation, predicted in the particle physics Standard Model, measures the process with enough precision to establish constraints on alternative theoretical models.

    David Reyna, manager of the Remote Sensing Department housed at Sandia’s California laboratory, was instrumental in the COHERENT experiment. Reyna first spearheaded a 2012 workshop at Sandia’s California lab that brought together leaders and researchers in the neutrino field. Reyna and Sandia researcher Belkis Cabrera-Palmer also oversaw the deployment of multiple detectors at ORNL as part of the COHERENT collaboration.

    “We have a long history at Sandia of investigating low-energy neutrino detection techniques with potential applications to reactor monitoring,” Reyna said. “For many years we have been working with the community on the development of low-threshold germanium detectors for potential Coherent elastic neutrino-nucleus scattering detection.”

    Cabrera-Palmer was in charge of analyzing three years of neutron background data collected with the Sandia-developed neutron scatter camera in five different locations across the SNS, a one-of-a-kind research facility that produces neutrons in a process called spallation.

    Fast turnaround of the analysis results guided the collaboration in deciding the location with background low enough to allow for detection,” Cabrera-Palmer said.

    2
    The detector on the left is the Sandia National Laboratories module for neutron monitoring. The next box after it is the shielding enclosure for the CsI detector that produced the results included in this publication. In the background are more of the collaboration’s detector systems that are currently taking data. (Photo courtesy of Sandia National Laboratories)

    Reyna and Cabrera-Palmer also supported the initial deployment of a High Purity Germanium Detector in collaboration with Lawrence Berkeley National Laboratory. Currently, Reyna and Cabrera-Palmer are working on the deployment of a Sandia-developed high-energy neutron detector, the Multiplicity and Recoil Spectrometer, for the project. Cabrera-Palmer will lead the deployment, simulation and analysis of the detector, which is scheduled to continuously collect and monitor neutron background data at the SNS for the next five years.

    Reyna said Sandia has leveraged its extensive expertise in fast-neutron detection in its ownership of the neutron background measurements for the COHERENT collaboration. Originally supported by an exploratory Laboratory Directed Research and Development in 2013, Sandia was able to make the critical initial measurements in the basement of the SNS that established the viability of the experiment.

    The SNS produces neutrons for scientific research and also generates a high flux of neutrinos as a byproduct. Placing the detector at SNS a mere 65 feet (20 meters) from the neutrino source vastly improved the chances of interactions and allowed the researchers to decrease the detector’s weight to just 32 pounds (14.5 kilograms) of cesium-iodide. In comparison, most neutrino detectors weigh thousands of tons. Although they are continuously exposed to solar, terrestrial and atmospheric neutrinos, they need to be massive because the interaction odds are more than 100 times lower than at SNS.

    Typically, neutrinos interact with individual protons or neutrons inside a nucleus. But in coherent scattering, an approaching neutrino sees the entire weak charge of the nucleus as a whole and interacts with all of it.

    The calculable fingerprint of neutrino-nucleus interactions predicted by the Standard Model and seen by COHERENT is not just interesting to theorists. In nature, it also dominates neutrino dynamics during neutron star formation and supernovae explosions. In addition, COHERENT’s data will help with interpretations of measurements of neutrino properties by experiments worldwide. The coherent scattering can be used to better understand the structure of the nucleus.

    Though the cesium-iodide detector observed coherent scattering beyond any doubt, COHERENT researchers will conduct additional measurements with at least three detector technologies to observe coherent neutrino interactions at distinct rates, another signature of the process. These detectors will further expand knowledge of basic neutrino properties, such as their intrinsic magnetism.

    See the full article here .

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    Sandia Campus
    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 8:25 am on August 3, 2017 Permalink | Reply
    Tags: 5 fundamental parameters from top quark decay, , , , Particle Physics,   

    From ATLAS: “5 fundamental parameters from top quark decay” 

    CERN ATLAS Higgs Event

    CERN/ATLAS
    ATLAS

    3rd August 2017
    ATLAS Collaboration

    Number 4 may shock you!

    1
    Figure 1: The radiation of decay products from a polarized top quark follows patterns like those shown here. An analysis of the radiation is used to measure top quark properties in a new analysis. (Image: ATLAS Collaboration/CERN)

    For many physicists, discovering “new physics” means bringing to light a new particle. Another path to discovery lies in carefully measuring the properties of known particles and the interactions between them. The ATLAS experiment has now released new results on the top quark’s interaction with the charged intermediate vector boson.

    While the Higgs boson, which escaped observation until as recently as 2012, is certainly the most intriguing elementary particle, the top quark is arguably second. Heavier than even the Higgs boson, the top quark packs as much mass as a gold nucleus into a single point like constituent. Precise measurements of the top quark have taken a great leap forward at the Large Hadron Collider (LHC), where the production rate is high and the backgrounds are low.

    In the recent paper [JHEP], the ATLAS collaboration presents results obtained from decays of polarized top quarks. The polarization occurs when top quarks are produced singly through the parity-violating weak interaction, rather than in pairs through the parity-conserving strong interaction. Singly-produced top quarks have only recently become an important tool for discovery.

    2
    Figure 2: The plot shows the strength of each of the decay patterns such as those shown in Figure 1. The red solid line is the Standard Model expectation. The data points are the measurement. The measurement is in very good agreement with the Standard Model. (Image: ATLAS Collaboration/CERN)

    Nine distinct decay patterns, examples of which are shown in Figure 1, can be discerned in these decays, similar to antennae patterns. These patterns depend upon five fundamental constants (called f1, f1+,f0+,δ-, and P) governing the interaction between the top, its partner the bottom quark, and the charged weak boson (W±). Current understanding of physics holds that the top quark couplings should be “left-handed” like those of the other quarks, and that they should be identical between the top quarks and its antiparticle, the top antiquark. The new measurements put that understanding to the test.

    By studying the full multidimensional decay patterns, ATLAS measures many properties of the top-bottom-W interaction at the same time and without some of the assumptions that have been made in the past. The analysis is known for both its complexity and its power. Results are shown in Figure 2. Five fundamental constants are determined from the decay. The fourth one, δ–, quantifies the matter-antimatter asymmetry in top quark decays. It is consistent with zero and consistent with the current understanding of fundamental physics. Shocking? Maybe – but physicists are slowly getting used to the idea that the Standard Model is an excellent description of nature.

    The analysis uses proton–antiproton collisions at 8 TeV, data collected at the LHC in 2012. Investigators are now applying even more refined techniques to collisions at a higher centre-of-mass energy of 13 TeV now being collected at CERN. Future measurements at higher precision may finally observe deviations from the Standard Model.

    Links:

    Analysis of the Wtb vertex from the measurement of triple-differential angular decay rates of single top quarks produced in the t-channel at s√ = 8 TeV with the ATLAS detector (arXiv:1707.05393) [Above].
    EPS 2017 presentation by Susana Cabrera Urban: Anomalous couplings in single top and searches for rare top quark couplings with the ATLAS detector
    See also the full lists of ATLAS Conference Notes and ATLAS Physics Papers.

    See the full article here .

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