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  • richardmitnick 9:24 am on December 17, 2021 Permalink | Reply
    Tags: "Redefining How Neutrinos Impede Dark Matter Searches", , Dark Matter Research, ,   

    From Physics (US) : “Redefining How Neutrinos Impede Dark Matter Searches” 

    About Physics

    From Physics (US)

    December 16, 2021
    Christopher Crockett

    A new definition of the “neutrino floor” in dark matter experiments clarifies the challenges ahead in differentiating neutrinos from WIMPs.

    Many underground labs are searching for dark matter in the form of weakly interacting massive particles (WIMPs).

    Dark Matter Research

    LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

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

    DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

    Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

    The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

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

    DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [CH].

    PandaX II Dark Matter experiment at The China Jinping Underground Laboratory [中国锦屏地下实验室](CN).

    Inside the ADMX experiment hall at The University of Washington (US). Credit Mark Stone U. of Washington. Axion Dark Matter Experiment.

    As the sensitivities of these experiments improve, they will have to contend with neutrinos, which can leave observational signatures remarkably like those predicted for dark matter. This challenge has prompted the idea of a “neutrino floor,” a theoretical limit on the types of dark matter particles that could be discovered (see Research News: Neutrinos Rising from the Floor). Now, Ciaran O’Hare of The University of Sydney (AU) proposes a new definition of the neutrino floor that is more statistically meaningful than previous calculations and does not depend on arbitrary experimental parameters [1].

    Hunts for WIMPs rely on spotting atomic nuclei scattered by dark matter particles. Unfortunately, neutrinos can also scatter atomic nuclei, producing similar signals. The neutrino floor is usually defined as the point at which the dark matter signal gets buried in the neutrino signal. But the floor isn’t a hard limit—it depends on uncertainties in the neutrino flux and can be overcome by detecting lots of events. This has led some to talk about a “neutrino fog,” a region of discovery space where differentiating dark matter from neutrinos is hard but not impossible.

    O’Hare’s new definition of the neutrino floor puts it at the edge of this fog. Relying on observed and calculated neutrino fluxes from many sources as well as a common dark matter model, it marks the point at which any dark matter experiment will start to be limited by the neutrino background. While paralleling previous calculations, the new boundary predicts that low- and high-mass WIMPs must scatter nuclei at a higher rate than previously thought to be discerned against the fog, while intermediate-mass WIMPs have a bit more leeway.

    Science paper:
    Physical Review Letters

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

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

     
  • richardmitnick 4:52 pm on December 8, 2021 Permalink | Reply
    Tags: "Optical cavities could be key to next generation interferometers", , , Atomic interferometry, Dark Matter Research, Devices to investigate signals from dark matter and gravitational waves., , Improving the future sensitivity of atom interferometers., ,   

    From The University of Birmingham (UK) via phys.org : “Optical cavities could be key to next generation interferometers” 

    From The University of Birmingham (UK)

    via

    phys.org

    1
    Fig. 1: Circulating pulse interferometry schematic. Circulating pulses occupy each of the two running wave modes in this example cavity, 6 km round trip with a 1 km baseline aligned with gravity. On each round trip, additional light is coupled into the cavity to compensate for losses. Serrodyne modulation, applied through a Pockels cell, shifts the frequency of each pulse on each pass to compensate for Doppler shifts. The pulse durations are maximized within the constraint that only one pulse may pass through the atoms (blue) or Pockels cell at a time. Credit:Communications Physics.

    A new concept has been developed that has the potential to assist new instruments in the investigation of fundamental science topics such as gravitational waves and dark matter.

    The concept is described in a paper written by UK Quantum Technology Hub Sensors and Timing researchers at the University of Birmingham and published in Communications Physics, and a related patent application filed by University of Birmingham Enterprise.

    It proposes a new method of using optical cavities to enhance atom interferometers—highly sensitive devices that use light and atoms to make ultra-precise measurements.

    Although itself challenging to implement, the concept presents a method of overcoming substantial technological challenges involved in the pursuit of atom interferometers operating at extreme momentum transfer—a technique which would allow atoms to be placed into a quantum superposition over large distances.

    This is key to enabling the sensitivities required for these devices to investigate signals from dark matter and gravitational waves. The exploration of dark matter, and the detection of gravitational waves from the very early Universe is key to developing our collective knowledge of fundamental physics.

    The new paper, written by Dr. Rustin Nourshargh, Dr. Samuel Lellouch and colleagues from the School of Physics and Astronomy, describes how synchronization of the input pulses, to realize a spatially resolved circulating pulse within the optical cavity, can facilitate a large momentum transfer without the need for drastic improvements in available laser power.

    Investigating dark matter and gravitational waves will not only facilitate a better understanding of the Universe’s history, but will also drive new ideas for improving the future sensitivity of atom interferometers. This will also be relevant to further exploiting atom interferometry in practical applications, such as providing new tools for navigation through enabling increased resilience against loss of GPS signals.

    Dr. Rustin Nourshargh, former doctoral researcher at the University of Birmingham and now Scientist at Oxford Ionics, said: “This optical cavity scheme offers a route to meeting the immense laser power requirements for future atom based gravitational wave detectors.”

    Dr. Samuel Lellouch, Research Fellow at the University of Birmingham, said: “By overcoming some of the most severe current technological barriers, this original scheme has a real potential to enable disruptive sensitivity levels in large-scale atom interferometers.”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The University of Birmingham (UK) has been challenging and developing great minds for more than a century. Characterised by a tradition of innovation, research at the University has broken new ground, pushed forward the boundaries of knowledge and made an impact on people’s lives. We continue this tradition today and have ambitions for a future that will embed our work and recognition of the Birmingham name on the international stage.

    The University of Birmingham is a public research university located in Edgbaston, Birmingham, United Kingdom. It received its royal charter in 1900 as a successor to Queen’s College, Birmingham (founded in 1825 as the Birmingham School of Medicine and Surgery), and Mason Science College (established in 1875 by Sir Josiah Mason), making it the first English civic or ‘red brick’ university to receive its own royal charter. It is a founding member of both the Russell Group (UK) of British research universities and the international network of research universities, Universitas 21.

    The student population includes 23,155 undergraduate and 12,605 postgraduate students, which is the 7th largest in the UK (out of 169). The annual income of the institution for 2019–20 was £737.3 million of which £140.4 million was from research grants and contracts, with an expenditure of £667.4 million.

    The university is home to the Barber Institute of Fine Arts, housing works by Van Gogh, Picasso and Monet; the Shakespeare Institute; the Cadbury Research Library, home to the Mingana Collection of Middle Eastern manuscripts; the Lapworth Museum of Geology; and the 100-metre Joseph Chamberlain Memorial Clock Tower, which is a prominent landmark visible from many parts of the city. Academics and alumni of the university include former British Prime Ministers Neville Chamberlain and Stanley Baldwin, the British composer Sir Edward Elgar and eleven Nobel laureates.

    Scientific discoveries and inventions

    The university has been involved in many scientific breakthroughs and inventions. From 1925 until 1948, Sir Norman Haworth was Professor and Director of the Department of Chemistry. He was appointed Dean of the Faculty of Science and acted as Vice-Principal from 1947 until 1948. His research focused predominantly on carbohydrate chemistry in which he confirmed a number of structures of optically active sugars. By 1928, he had deduced and confirmed the structures of maltose, cellobiose, lactose, gentiobiose, melibiose, gentianose, raffinose, as well as the glucoside ring tautomeric structure of aldose sugars. His research helped to define the basic features of the starch, cellulose, glycogen, inulin and xylan molecules. He also contributed towards solving the problems with bacterial polysaccharides. He was a recipient of the Nobel Prize in Chemistry in 1937.

    The cavity magnetron was developed in the Department of Physics by Sir John Randall, Harry Boot and James Sayers. This was vital to the Allied victory in World War II. In 1940, the Frisch–Peierls memorandum, a document which demonstrated that the atomic bomb was more than simply theoretically possible, was written in the Physics Department by Sir Rudolf Peierls and Otto Frisch. The university also hosted early work on gaseous diffusion in the Chemistry department when it was located in the Hills building.

    Physicist Sir Mark Oliphant made a proposal for the construction of a proton-synchrotron in 1943, however he made no assertion that the machine would work. In 1945, phase stability was discovered; consequently, the proposal was revived, and construction of a machine that could surpass proton energies of 1 GeV began at the university. However, because of lack of funds, the machine did not start until 1953. The DOE’s Brookhaven National Laboratory (US) managed to beat them; they started their Cosmotron in 1952, and had it entirely working in 1953, before the University of Birmingham.

    In 1947, Sir Peter Medawar was appointed Mason Professor of Zoology at the university. His work involved investigating the phenomenon of tolerance and transplantation immunity. He collaborated with Rupert E. Billingham and they did research on problems of pigmentation and skin grafting in cattle. They used skin grafting to differentiate between monozygotic and dizygotic twins in cattle. Taking the earlier research of R. D. Owen into consideration, they concluded that actively acquired tolerance of homografts could be artificially reproduced. For this research, Medawar was elected a Fellow of the Royal Society. He left Birmingham in 1951 and joined the faculty at University College London (UK), where he continued his research on transplantation immunity. He was a recipient of the Nobel Prize in Physiology or Medicine in 1960.

     
  • richardmitnick 11:59 am on June 13, 2021 Permalink | Reply
    Tags: " 'Sterile neutrinos' may be portal to the dark side", “BeEST”: “Beryllium Electron-capture with Superconducting Tunnel junctions.”, , , , Dark Matter Research, , Using nuclear decay in high-rate quantum sensors in the search for "sterile neutrinos".   

    From DOE’s Lawrence Livermore National Laboratory (US) : “Sterile neutrinos may be portal to the dark side” 

    From DOE’s Lawrence Livermore National Laboratory (US)

    4.27.21 [Just now in social media.]

    Anne M Stark
    stark8@llnl.gov
    925-422-9799

    1
    Schematic of the “BeEST” experiment. Radioactive beryllium-7 is implanted into the superconducting sensor. Precision measurements of the decay products could indicate the presence of hypothesized “sterile neutrinos”.

    “Sterile neutrinos” are theoretically predicted new particles that offer an intriguing possibility in the quest for understanding the Dark Matter in our universe.

    Unlike the known “active” neutrinos in the Standard Model (SM) of Particle Physics, these sterile neutrinos do not interact with normal matter as they move through space, making them very difficult to detect.

    A team of interdisciplinary researchers, led by Lawrence Livermore National Laboratory (LLNL) and the Colorado School of Mines (US), has demonstrated the power of using nuclear decay in high-rate quantum sensors in the search for sterile neutrinos. The findings are the first measurements of their kind.

    The research has been featured recently as a DOE Office of Science Highlight and will jump-start an extended project to look for one of the most promising candidates for dark matter, the strange unidentified material that permeates the universe and accounts for 85 percent of its total mass.

    The experiment involves implanting radioactive beryllium-7 atoms into superconducting sensors developed at LLNL and has been nicknamed the “BeEST” for “Beryllium Electron-capture with Superconducting Tunnel junctions.” When the beryllium-7 decays by electron capture into lithium-7 and a neutrino, the neutrino escapes from the sensor, but the recoil energy of the lithium-7 provides a measure of the neutrino mass. If a heavy sterile neutrino with mass mc^2 were to be generated in a faction of the decays, the lithium-7 recoil energy would be reduced and produce a measurable signal, even though the elusive neutrino itself is not detected directly.

    With a measurement time of just 28 days using a single sensor, the data excludes the existence of sterile neutrinos in the mass range of 100 to 850 kiloelectronvolts down to a 0.01 percent level of mixing with the active neutrinos — better than all previous decay experiments in this range. In addition, simulations on LLNL supercomputers have helped the team understand some of the materials effects in the detector that need to be accounted for to gain confidence in potential sterile neutrino detection events.

    “This research effort lays the groundwork for even more powerful searches for these new particles using large arrays of sensors with new superconducting materials,” said LLNL scientist Stephan Friedrich, lead author of the research appearing in Physical Review Letters.

    The Standard Model of Particle Physics is one of the crowning achievements in modern science and the cornerstone of current subatomic studies. Despite its success, the SM is known to be incomplete, and physics beyond the Standard Model (BSM) is required to develop a full description of the universe. The neutrino sector offers an intriguing avenue for BSM physics as the observation of nonzero neutrino masses currently provides the only confirmed violation of the SM as it was originally constructed.

    “Sterile neutrinos are exciting because they are strong candidates for so-called ‘warm’ dark matter, and they also may help to address the origin of the matter-antimatter asymmetry of the universe,” Friedrich said.

    Other LLNL authors include Geonbo Kim, Vincenzo Lordi and Amit Samanta.

    This research is funded by the Laboratory Directed Research and Development program.

    _____________________________________________________________________________________

    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for 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. https://home.dtm.ciw.edu.


    _____________________________________________________________________________________

    Dark Matter Research

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

    DOE’s Lawrence Livermore National Laboratory (LLNL) (US) is an American federal research facility in Livermore, California, United States, founded by the University of California-Berkeley (US) in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System (US). In 2012, the laboratory had the synthetic chemical element livermorium named after it.
    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.” Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    The Laboratory is located on a one-square-mile (2.6 km^2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

    LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence, director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

    The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

    Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the DOE’s Los Alamos National Laboratory(US) and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

    Historically, the DOE’s Lawrence Berkeley National Laboratory (US) and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.

    The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.” The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS. The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.

    On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km^2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.

    LLNL/NIF

    DOE Seal

    NNSA

     
  • richardmitnick 11:53 am on February 23, 2020 Permalink | Reply
    Tags: , , , , , , , Dark Matter Research, , , ,   

    From EarthSky: “What is dark matter?” 

    1

    From EarthSky

    February 23, 2020
    Andy Briggs

    Dark Matter doesn’t emit light. It can’t be directly observed with any of the existing tools of astronomers. Yet astrophysicists believe it and Dark Energy make up most of the mass of the cosmos. What dark matter is, and what it isn’t. here.

    1
    Since the 1930s, astrophysicists have been trying to explain why the visible material in galaxies can’t account for how galaxies are shaped, or how they behave. They believe a form of dark or invisible matter pervades our universe, but they still don’t know what this dark matter might be. Image via ScienceAlert.

    Dark matter is a mysterious substance thought to compose perhaps about 27% of the makeup of the universe. What is it? It’s a bit easier to say what it isn’t.

    It isn’t ordinary atoms – the building blocks of our own bodies and all we see around us – because atoms make up only somewhere around 5% of the universe, according to a cosmological model called the Lambda Cold Dark Matter Model (aka the Lambda-CDM model, or sometimes just the Standard 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

    Dark Matter isn’t the same thing as Dark Energy, which makes up some 68% of the universe, according to the Standard Model.

    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.

    Dark matter is invisible; it doesn’t emit, reflect or absorb light or any type of electromagnetic radiation such as X-rays or radio waves. Thus, dark matter is undetectable directly, as all of our observations of the universe, apart from the detection of gravitational waves, involve capturing electromagnetic radiation in our telescopes.

    Gravitational waves Werner Benger-ZIB-AEI-CCT-LSU

    Yet dark matter does interact with ordinary matter. It exhibits measurable gravitational effects on large structures in the universe such as galaxies and galaxy clusters. Because of this, astronomers are able to make maps of the distribution of dark matter in the universe, even though they cannot see it directly.

    They do this by measuring the effect dark matter has on ordinary matter, through gravity.

    2
    This all-sky image – released in 2013 – shows the distribution of dark matter across the entire history of the universe as seen projected on the sky. It’s based on data collected with the European Space Agency’s Planck satellite.

    ESA/Planck 2009 to 2013

    Dark blue areas represent regions that are denser than their surroundings. Bright areas represent less dense regions. The gray portions of the image correspond to patches of the sky where foreground emission, mainly from the Milky Way but also from nearby galaxies, prevents cosmologists from seeing clearly. Image via ESA.

    There is currently a huge international effort to identify the nature of dark matter. Bringing an armory of advanced technology to bear on the problem, astronomers have designed ever-more complex and sensitive detectors to tease out the identity of this mysterious substance.

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    Dark matter might consist of an as yet unidentified subatomic particle of a type completely different from what scientists call baryonic matter – that’s just ordinary matter, the stuff we see all around us – which is made of ordinary atoms built of protons and neutrons.

    The list of candidate subatomic particles breaks down into a few groups: there are the WIMPs (Weakly Interacting Massive Particles), a class of particles thought to have been produced in the early universe. Astronomers believe that WIMPs might self-annihilate when colliding with each other, so they have searched the skies for telltale traces of events such as the release of neutrinos or gamma rays. So far, they’ve found nothing. In addition, although a theory called supersymmetry predicts the existence of particles with the same properties as WIMPs, repeated searches to find the particles directly have also found nothing, and experiments at the Large Hadron Collider to detect the expected presence of supersymmetry have completely failed to find it.

    Standard Model of Supersymmetry via DESY

    CERN/LHC Map


    CERN LHC Maximilien Brice and Julien Marius Ordan


    SixTRack CERN LHC particles

    Several different types of detector have been used to detect WIMPs. The general idea is that very occasionally, a WIMP might collide with an ordinary atom and release a faint flash of light, which can be detected. The most sensitive detector built to date is XENON1T, which consists of a 10-meter cylinder containing 3.2 tons of liquid xenon, surrounded by photomultipliers to detect and amplify the incredibly faint flashes from these rare interactions. As of July 2019, when the detector was decommissioned to pave the way for a more sensitive instrument, the XENONnT, no collisions between WIMPs and the xenon atoms had been seen.

    XENON1T at Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy


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

    At the moment, a hypothetical particle called the Axion is receiving much attention.

    CERN CAST Axion Solar Telescope

    As well as being a strong candidate for dark matter, the existence of axions is also thought to provide the answers to a few other persistent questions in physics such as the Strong CP Problem.

    Fritz Zwicky discovered Dark Matter in the 1930s 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.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for 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. https://home.dtm.ciw.edu

    The Vera C. Rubin Observatory currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Some astronomers have tried to negate the need the existence of dark matter altogether by postulating something called Modified Newtonian dynamics (MOND).

    Mordehai Milgrom, MOND theorist, is an Israeli physicist and professor in the department of Condensed Matter Physics at the Weizmann Institute in Rehovot, Israel http://cosmos.nautil.us

    MOND Modified Newtonian Dynamics a Humble Introduction Marcus Nielbock

    The idea behind this is that gravity behaves differently over long distances to what it does locally, and this difference of behavior explains phenomena such as galaxy rotation curves which we attribute to dark matter. Although MOND has its supporters, while it can account for the rotation curve of an individual galaxy, current versions of MOND simply cannot account for the behavior and movement of matter in large structures such as galaxy clusters and, in its current form, is thought unable to completely account for the existence of dark matter. That is to say, gravity does behave in the same way at all scales of distance. Most versions of MOND, on the other hand, have two versions of gravity, the weaker one occurring in regions of low mass concentration such as in the outskirts of galaxies. However, it is not inconceivable that some new version of MOND in the future might yet account for dark matter.

    Although some astronomers believe we will establish the nature of dark matter in the near future, the search so far has proved fruitless, and we know that the universe often springs surprises on us so that nothing can be taken for granted.

    The approach astronomers are taking is to eliminate those particles which cannot be dark matter, in the hope we will be left with the one which is.

    It remains to be seen if this approach is the correct one.

    See the full article here .


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    Please help promote STEM in your local schools.

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    Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.

     
  • richardmitnick 1:19 pm on January 21, 2020 Permalink | Reply
    Tags: , , , , Dark Matter Research, , ,   

    From Symmetry: “The other dark matter candidate” 

    Symmetry Mag
    From Symmetry<

    01/21/20
    Laura Dattaro

    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    CERN CAST Axion Solar Telescope

    As technology improves, scientists discover new ways to search for theorized dark matter particles called axions.

    In the early 1970s, physics had a symmetry problem. According to the Standard Model, the guiding framework of particle physics, a symmetry between particles and forces in our universe and a mirror version should be broken.

    Standard Model of Particle Physics

    It was broken by the weak force, a fundamental force involved in processes like radioactive decay.

    This breaking should feed into the interactions mediated by another fundamental force, the strong force. But experiments show that, unlike the weak force, the strong force obeys mirror symmetry perfectly. No one could explain it.

    The problem confounded physicists for years. Then, in 1977, physicists Roberto Peccei and Helen Quinn found a solution: a mechanism that, if it existed, would cause the strong force to obey this symmetry and right the Standard Model.

    Shortly after, Frank Wilczek and Steven Weinberg—both of whom went on to win the Nobel Prize—realized that this mechanism creates an entirely new particle. Wilczek ultimately dubbed this new particle the axion, after a dish detergent with the same name, for its ability to “clean up” the symmetry problem.

    Several years later, the theoretical axion was found not only to solve the symmetry problem, but also to be a possible candidate for dark matter, the missing matter that scientists think makes up 85% of the universe but the true nature of which is unknown.

    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.

    Fritz Zwicky from http:// palomarskies.blogspot.com

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for 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. https://home.dtm.ciw.edu

    The LSST, or Large Synoptic Survey Telescope is to be named the Vera C. Rubin Observatory by an act of the U.S. Congress.

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background [CMB]hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    [caption id="attachment_73741" align="alignnone" width="632"] CMB per ESA/Planck

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA


    Inside the ADMX experiment hall at the University of Washington Credit Mark Stone U. of Washington. Axion Dark Matter Experiment

    Despite its theoretical promise, though, the axion stayed in relative obscurity, due to a combination of its strange nature and being outshone by another new dark matter candidate, called a WIMP, that seemed even more like a sure thing.

    But today, four decades after they were first theorized, axions are once again enjoying a moment in the sun, and may even be on the verge of detection, poised to solve two major problems in physics at once.

    “I think WIMPs have one last hurrah as these multiton experiments come online,” says MIT physicist Lindley Winslow. “Since they’re not done building those yet, we have to take a deep breath and see if we find something.

    “But if you ask me the thing we need to be ramping up, it’s axions. Because the axion has to be there, or we have other problems.”

    Around the time the axion was proposed, physicists were developing a theory called Supersymmetry, which called for a partner for every known particle.

    Standard Model of Supersymmetry via DESY

    The newly proposed dark matter candidate called a WIMP—or weakly interacting massive particle—fit beautifully with the theory of Supersymmetry, making physicists all but certain they’d both be discovered.

    Even more promising was that both the supersymmetric particles and the theorized WIMPs could be detected at the Large Hadron Collider at CERN.

    LHC

    CERN map


    CERN LHC Maximilien Brice and Julien Marius Ordan


    CERN LHC particles

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    CERN ATLAS Image Claudia Marcelloni CERN/ATLAS

    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    “People just knew nature was going to deliver supersymmetric particles at the LHC,” says University of Washington physicist Leslie Rosenberg. “The LHC was a machine built to get a Nobel Prize for detecting Supersymmetry.”

    Experiments at the LHC made another Nobel-worthy discovery: the Higgs boson. But evidence of both WIMPS and Supersymmetry has yet to appear.

    Peter Higgs

    CERN CMS Higgs Event May 27, 2012

    CERN ATLAS Higgs Event

    Axions are even trickier than WIMPs. They’re theorized to be extremely light—a millionth of an electronvolt or so, about a trillion times lighter than the already tiny electron—making them next to impossible to produce or study in a traditional particle physics experiment. They even earned the nickname “invisible axion” for the unlikeliness they’d ever be seen.

    But axions don’t need to be made in a detector to be discovered. If axions are dark matter, they were created at the beginning of the universe and exist, free-floating, throughout space. Theorists believe they also should be created inside of stars, and because they’re so light and weakly interacting, they’d be able to escape into space, much like other lightweight particles called neutrinos. That means they exist all around us, as many as 10 trillion per cubic centimeter, waiting to be detected.

    In 1983, newly minted physics professor Pierre Sikivie decided to tackle this problem, taking inspiration from a course he had just taught on electromagnetism. Sikivie discovered that axions have another unusual property: In the presence of an electromagnetic field, they should sometimes spontaneously convert to easily detectable photons.

    “What I found is that it was impossible or extremely difficult to produce and detect axions,” Sikivie says. “But if you ask a less ambitious goal of detecting the axions that are already there, axions already there either as dark matter or as axions emitted by the sun, that actually became feasible.”

    When Rosenberg, then a postdoc working on cosmic rays at the University of Chicago, heard about Sikivie’s breakthrough—what he calls “Pierre’s Great Idea”—he knew he wanted to dedicate his work to the search.

    “Pierre’s paper hit me like a rock in the head,” Rosenberg says. “Suddenly, this thing that was the invisible axion, which I thought was so compelling, is detectable.”

    Rosenberg began work on what’s now called the Axion Dark Matter Experiment, or ADMX. The concept behind the experiment is relatively simple: Use a large magnet to create an electromagnetic field, and wait for the axions to convert to photons, which can then be detected with quantum sensors.

    When work on ADMX began, the technology wasn’t sensitive enough to pick up the extremely light axions. While Rosenberg kept the project moving forward, much of the field has focused on WIMPs, building ever-larger dark matter detectors to find them.

    But neither WIMPs nor supersymmetric particles have been discovered, pushing scientists to think creatively about what happens next.

    “That’s caused a lot of people to re-evaluate what other dark matter models we have,” says University of Michigan theorist Ben Safdi. “And when people have done that re-evaluation, the axion is the natural candidate that’s still floating around. The downfall of the WIMP has been matched exactly by the rise of axions in terms of popularity.”

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:32 pm on February 14, 2019 Permalink | Reply
    Tags: , , , , , Dark Matter Research, , , The Kavli Institute for the Physics and Mathematics of the Universe   

    From The Kavli Institute for the Physics and Mathematics of the Universe: “New Map of Dark Matter Puts the Big Bang Theory on Trial” 

    KavliFoundation

    From The Kavli Institute for the Physics and Mathematics of the Universe

    Kavli IPMU
    Kavli IMPU

    The prevailing view of the universe has just passed a rigorous new test, but the mysteries of dark matter and dark energy remain frustratingly unsolved.

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LUX Dark matter Experiment at SURF, Lead, SD, USA

    ADMX Axion Dark Matter Experiment, U Uashington

    A NEW COSMIC MAP was unveiled in August, plotting where the mysterious substance called dark matter is clumped across the universe.

    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

    To immense relief—and frustration—the map is just what scientists had expected. The distribution of dark matter agrees with our current understanding of a universe born with certain properties in a Big Bang, 13.8 billion years ago.

    But for all the map’s confirmatory power, it still tells us little about the true identity of dark matter, which acts as an invisible scaffold for galaxies and cosmic structure. It also does not explain an even bigger factor shaping the cosmos, known as dark energy, an enigmatic force seemingly pushing the universe apart at ever greater speeds. Tantalizingly, however, a small discrepancy between the new findings and previous observations of the early universe might just crack open the door for new physics.

    To discuss these issues, The Kavli Foundation turned to three scientists involved in creating this new cosmic map, compiled by the Dark Energy Survey.

    Adam Hadhazy, Fall 2017

    The participants were:

    SCOTT DODELSON – is a cosmologist and the head of the Department of Physics at Carnegie Mellon University. He is one of the lead scientists behind the Dark Energy Survey’s new map of cosmic structure, which he worked on at the Fermi National Accelerator Laboratory and as a professor at the Kavli Institute for Cosmological Physics at the University of Chicago.

    3
    Map of dark matter made from gravitational lensing measurements of 26 million galaxies in the Dark Energy Survey. The map covers about 1/30th of the entire sky and spans several billion light years in extent. Red regions have more dark matter than average, blue regions less dark matter. Image credit: Chihway Chang/Kavli Institute for Cosmological Physics at the University of Chicago/DES Collaboration.

    RISA WECHSLER – is an associate professor of physics at Stanford University and the SLAC National Accelerator Laboratory, as well as a member of the Kavli Institute for Particle Astrophysics and Cosmology. A founder of the Dark Energy Survey, Wechsler is also involved in two next-generation projects that will delve even deeper into the dark universe.
    GEORGE EFSTATHIOU – is a professor of astrophysics and the former director of the Kavli Institute for Cosmology at the University of Cambridge. Along with his work on the Dark Energy Survey, Efstathiou is a science team leader for the European Space Agency’s Planck spacecraft, which between 2009 and 2013 created a detailed map of the early universe.

    The following is an edited transcript of their roundtable discussion. The participants have been provided the opportunity to amend or edit their remarks.

    THE KAVLI FOUNDATION: The Dark Energy Survey just confirmed that matter as we know it makes up only four percent of the universe. That means 96 percent is stuff we can neither see nor touch, and we have pretty much no idea what it really is. Why are these new findings actually good news?

    RISA WECHSLER: It does seem very strange that the results are good news, right? Forty years ago, nobody would’ve guessed that we apparently live in a universe in which most of the matter is stuff that doesn’t interact with us, and most of the energy is not even matter! It’s still super mind-blowing.

    But we’ve kept making increasingly precise measurements of the universe, and that’s where the Dark Energy Survey results come in. They are the most precise measurements of the density of matter and how it’s clumped in the local universe. In the past, we have measured the density of matter in the young, distant universe. So the Dark Energy Survey is really allowing us to test our understanding of the universe’s evolution, which we’ve formalized as the standard model of Big Bang cosmology, in a totally new way.

    Still, it’s certainly possible that we may have something wrong.

    SCOTT DODELSON: These data, along with precise measurements taken by other projects, might start showing small hints of disagreement, or tension, as we call it, with our current understanding of how the universe began and is now actually expanding at increasing speeds.

    As Risa just said, we’re not sure our current way of thinking is correct because it essentially requires us to make stuff up, namely dark matter and dark energy. It could be that we really are just a month away from a scientific revolution that will upend our whole understanding about cosmology and does not require these things.

    GEORGE EFSTATHIOU: Those measurements of the matter and energy in the young, distant universe that Risa referred to were obtained just a few years ago, when a different program called Planck looked at the relic radiation of the Big Bang, which we call the cosmic microwave background [CMB, see below]. Although the Planck spacecraft’s measurements support the model we’re talking about, one is always uneasy having to postulate things, like dark matter and dark energy, that have not been observed. That’s why the Dark Energy Survey is very important—it can stringently test our knowledge about the birth of the universe by comparing it to the actual structure of the modern-day and young universe.

    TKF: The Dark Energy Survey kicked off four years ago, so you’ve been waiting a long time for these results to come in. What was your initial reaction?

    DODELSON: It was the most amazing experience of my scientific career. On July 7, 2017, a date I will always remember, we had 50 people join a conference call. No one knew what the data were going to say because they were blinded, which guards against accidentally biasing the results to be something you “want” them to be. Then one of the leaders of the lensing analysis, Michael Troxel, ran a computer script on the data, unblinding it, and shared his screen with everybody on the call. We all got to see our results compared to Planck’s. They were in such close agreement, independently of each other. We all just gasped and then clapped.

    WECHSLER: I was on that conference call, too. It was really exciting. I’ve been working on this survey since we wrote the first proposal in 2004, so it felt like a culmination.

    TKF: In 2013, Planck gave us a highly accurate “baby” picture of the universe.

    CMB per ESA/Planck

    ESA/Planck 2009 to 2013

    Now we have a highly precise picture of the universe in a later epoch. George, you were a leader on the Planck mission. What do you see when you look at these two different snapshots in time?

    EFSTATHIOU: The “baby” picture is consistent with a universe mostly made of dark matter and dark energy. It is also consistent with the idea that the universe underwent an exponential expansion in its earliest moments, known as inflation.

    Inflation

    4
    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:
    5

    So how does the baby picture extrapolate to the modern, “grown up” universe? As the new Dark Energy Survey results show, the pictures are remarkably consistent.

    DODELSON: We’re all astonished that these two pictures agree to the extent they do. Here’s an example. Let’s say you bought Berkshire Hathaway stock in 1970. Say it was $10 a share then and today it’s $250,000 a share. If you were to predict back then that today it would be $250,000, plus or minus $1,000, people would’ve thought you were nuts. But basically, that’s what we’ve done. When the universe was very young, only 380,000 years old, it was also very “smooth.” Matter was so evenly distributed. Today though—more than 13 billion years later—matter in the cosmos is highly, highly clumped in galaxies, stars, planets and other objects. This is what one would anticipate with cosmic expansion, and with the Dark Energy Survey, we’ve been able to confirm the prediction of this cosmic unevenness to a remarkable degree.

    WECHSLER: What’s really helped us make the precise measurements with Dark Energy Survey is that for the first time, we’re looking over a much larger area, about one-thirtieth, of the sky. That’s three or four times larger than the largest dark matter map we have ever made before. We are also able to make that map essentially over half the age of the universe, from now until about seven billion years ago, by collecting light shining from distant galaxies. So we’re able to tell this story over half of the universe’s history, and it remains consistent throughout.

    There are some small disagreements with the Planck results, but I don’t think we should be too worried yet about them.

    EFSTATHIOU: It would’ve been very interesting if the results had significantly increased the tension with the cosmological standard model, which is the foundation for understanding why, beginning with the Big Bang, the universe is undergoing an accelerated expansion. Some previous surveys had suggested that there might be a problem, though I thought that these results were questionable. In my view, one should rely on the data and not be alarmed if our theories disagree with observations. The universe is what it is.

    TKF: Yet a Nature News story characterized George’s view on the discrepancies as “worrisome.”

    EFSTATHIOU: Well, yes, there have been some claims of tension between the clumping measured in the local universe and Planck’s observations of the distant universe. Some other observations have suggested that the late-time, local universe is expanding at a faster rate than expected from Planck.

    If we were able to say convincingly that there was a real problem posed by any of these individual pieces of data, then we’d have to abandon our standard model of cosmology. We would need new physics, and the sort of physics that we would need would be in the exotic territory, overturning decades of otherwise independently supported physical laws. So it’s a big deal.

    In the past, these sorts of tensions have come and gone. When we wrote the 2013 Planck papers, the results then were in tension with most of astrophysics. Then two years later, some of these tensions had disappeared, and now in 2017, they’ve reemerged. So these things come and go. We need to set a high threshold for our science before launching into explanations based on new physics.

    TKF: It almost sounds like, “if it ain’t broke yet, don’t fix it.”

    EFSTATHIOU: We need to be sure it’s broke before fixing it.

    WECHSLER: I agree with George. There’s a very high bar to show you really understand all of the potential sources of error before taking the big leap of abandoning our current, well-evidenced conception about the universe. I don’t think we’re there yet. It means that we should be really excited about the continuing Dark Energy Survey, as well as all the other upcoming surveys and projects.

    TKF: Indeed, these new results are based on a year’s-worth of measurements out of a total of five years. What might we expect after four more years of data have been crunched?

    WECHSLER: With four times more data, our map of dark matter will be even more precise. I also expect there will be improvements in our analysis methods. There will also be a bunch of other new things that the Dark Energy Survey should discover, including new dwarf galaxies around our Milky Way galaxy that we’ve long thought must be there but couldn’t find. There’s lots more to look forward to!

    DODELSON: The increased precision Risa just talked about will enable us to hit the standard model of cosmology as hard as it’s ever been hit. Disproving the current model will revolutionize the way we think about the universe, so that’s the most exciting thing that I can imagine happening.

    TKF: How are astrophysicists extending the hunt for dark matter and dark energy? Risa, let’s start with you, because you are closely involved in two next-generation “dark universe” projects.

    WECHSLER: With the Dark Energy Spectroscopic Instrument, or DESI [pronounced “DEZ-ee”], we’ll be getting what we call spectra, or detailed observations of the light from about 35 million galaxies and quasars, which are galaxies that appear extra bright because their central black holes are actively devouring matter.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    That’s about 10 times more spectra data than we’ve collected from all instruments, so you can imagine that will be really transformative. With DESI, we will be able to independently measure the universe’s expansion rate and how fast its structure of matter and dark matter grow, both of which are influenced by dark energy. Then when you compare those measurements, you get a precise test of the physics governing the universe. DESI will start in 2019 using a telescope in Arizona.

    The other major new instrument I’m working on is the Large Synoptic Survey Telescope, LSST.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    It will make observations just like the Dark Energy Survey, but at substantially higher precision. In fact, it will cover about four times more area, and the billions of galaxies it sees will be much deeper and farther away. LSST will be a new observatory, being built in Chile right now, and it’s scheduled to begin in about 2022.

    DODELSON: My guess is that both projects will raise new scientific questions. We’ve already seen that with the Dark Energy Survey. Questions shift over time and evolve, so I’m not sure we know what the most exciting thing we’re going to learn from LSST or DESI is.

    EFSTATHIOU: One of my hopes for Planck was that the standard model of cosmology would break and it didn’t. But wouldn’t it be absolutely great for cosmology and for physics if this happened? So we should plug away and see. Maybe we’ll be lucky.

    TKF: If you had to place a bet on what dark matter and dark energy actually are, where would you put your chips?

    DODELSON: We’re living in an era of cognitive dissonance. There is all this cosmological evidence for the existence of dark matter, but over the last 30 years, we’ve run all these experiments and haven’t found it. My bet is that we’re looking at things all wrong. Someone who’s 8 years old today is going to come around and figure out how to make sense of all the data without evoking mysterious new substances.

    EFSTATHIOU: What odds are you giving on that, Scott?

    DODELSON: I’m betting $2,000 of George’s money. [Laughter]

    EFSTATHIOU: I wouldn’t put a bet on any specific candidate for the dark matter. But I bet that dark energy is the cosmological constant, a fudge factor invented by Einstein describing the density of energy in a vacuum.

    WECHSLER: I’m basically with George on this one. I think if Scott’s right, that’ll be wonderful—but that definitely isn’t where I would place my money.

    I think it’s very likely that 15 years from now, we will just then be measuring that dark energy is caused by this cosmological constant. We will be able to shrink the error bars and find that our present model still works.

    On dark matter, I think it’s much less clear. For a long time, the most popular candidate was this thing called the WIMP, or a Weakly Interacting Massive Particle. That idea is still popular and totally possible, but a lot of the particles that could be that kind of dark matter are already ruled out. The other really compelling candidate is a subatomic particle called the axion. People are just getting to a place where they’re able to start searching for these particles that we think are going to be extremely difficult to detect. It’s also possible that dark matter might surprise us, that it’s some new kind of particle that we don’t have the techniques to look for yet.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Kavli IPMU (Kavli Institute for the Physics and Mathematics of the Universe) is an international research institute with English as its official language. The goal of the institute is to discover the fundamental laws of nature and to understand the Universe from the synergistic perspectives of mathematics, astronomy, and theoretical and experimental physics. The Institute for the Physics and Mathematics of the Universe (IPMU) was established in October 2007 under the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Sports, Science and Technology in Japan with the University of Tokyo as the host institution. IPMU was designated as the first research institute within the University of Tokyo Institutes for Advanced Study (UTIAS) in January 2011. It received an endowment from The Kavli Foundation and was renamed the “Kavli Institute for the Physics and Mathematics of the Universe” in April 2012. Kavli IPMU is located on the Kashiwa campus of the University of Tokyo, and more than half of its full-time scientific members come from outside Japan. http://www.ipmu.jp/
    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

     
  • richardmitnick 12:01 pm on July 17, 2018 Permalink | Reply
    Tags: , Dark Matter Research, , ,   

    From Science and Technology Facilities Council via Lawrence Berkeley National Lab: “UK delivers super-cool kit to USA for Next-Generation Dark Matter Experiment” 


    From Science and Technology Facilities Council

    via

    Berkeley Logo

    From Lawrence Berkeley National Lab

    17 July 2018
    Jake Gilmore
    jake.gilmore@stfc.ac.uk

    A huge UK built titanium chamber designed to keep its contents at a cool -100C and weighing as much as an SUV has been shipped to the United States, where it will soon become part of a next-generation dark matter detector to hunt for the long-theorised elusive dark matter particle called a WIMP (Weakly Interacting Massive Particle).

    This hunt is important because the nature of dark matter, which physicists describe as the invisible component or ‘missing mass’ in the universe, has eluded scientists since its existence was deduced by Swiss astronomer Fritz Zwicky in 1933. The quest to find out what dark matter is made of, or whether it can be explained by tweaking the known laws of physics, is considered one of the most pressing questions in particle physics, on a par with the previous hunt for the Higgs boson.

    The cryostat chamber was built by a team of engineers at the UK’s Science and Technology Facilities Council’s Rutherford Appleton Laboratory in Oxfordshire, and journeyed around the world to the LUX-Zeplin (LZ) experiment, located 1400m underground at the Sanford Underground Research Facility (SURF) in South Dakota.

    LBNL Lux Zeplin project at SURF

    1
    A worker inspects the titanium cryostat for the LUX-ZEPLIN experiment in a clean room. (Credit: Matt Kapust/SURF)

    After being delivered to the surface facility at SURF the Outer Cryostat Vessel (OCV) of the cryostat chamber spent five weeks being fully assembled and leak checked in the SURF Assembly Lab (SAL) clean room. It has now been disassembled and packaged for transportation from the surface to the underground location at SURF. Meanwhile the Inner Cryostat Vessel is now in the SAL clean room getting prepared for the leak tests.

    STFC’s Dr Pawel Majewski, technical lead for the cryostat, said: “The cryostat was a feat of engineering with some very stringent and challenging requirements to meet. Because of the huge mass of the cryostat – 2,000kgs – we had to make sure it was made of ultra radio-pure titanium. It took nearly two years to find a pure enough sample to work with. Eventually we got it from one of the world’s leading titanium suppliers in the US where Electron Beam Cold Heart technology was used to melt the titanium.

    “This type of ultra-pure titanium is used, for example, in the healthcare industry to fabricate a pacemaker encapsulation. In our case it is used to hold the heart of the experiment.”

    It took two-and-a-half years to design the specialist equipment, and another two years to build in Italy by a company specialising in vessels and pipes fabrication only from titanium.

    The cryostat is a vital part of LZ, as it keeps the detector at freezing temperatures. This is crucial because the detector uses xenon – which at room temperature is a gas. But for the experiment to work, the xenon, which itself has low background radiation, must be kept in a liquid state, which is only achievable at around -100C.

    LZ is the latest experiment to hunt for the long-theorised elusive dark matter particle called a WIMP (Weakly Interacting Massive Particle). Many scientists believe finding WIMPs will provide the answer to one of the most pressing questions in physics – what is dark matter? WIMPS are thought to make up the most of dark matter – the as-yet-unknown substance which makes up about 85% of the universe. But because WIMPs are thought not to interact with normal matter, they are practically invisible using traditional detection methods.

    Liquid xenon emits a flash of light when struck by a particle, and this light can be detected by very sensitive photon detectors called photomultiplier tubes. If a WIMP collides with a xenon nucleus we expect it to produce a burst of light.

    Before delivery to SURF the cryostat underwent several weeks of rigorous testing and a month-long thorough clean from an expert cleaning company in California. Five years after the design efforts started, the cryostat arrived safely at SURF and the LZ team then carefully unwrapped it and put it into place.

    “It’s a great experience to see all of the planning for LZ paying off with the arrival of components,” said Murdock “Gil” Gilchriese, LZ project director and a Berkeley Lab physicist. “We look forward to seeing these components fully assembled and installed underground in preparation for the start of LZ science.”

    UK PI for LZ is Professor Henrique Araujo from Imperial College London and he said: “It is incredibly gratifying to see LZ beginning to take shape. Seeing the cryostat arrive is a milestone moment as it has been years in the making.

    “Now we have to wait for the other constituent elements to arrive before we can start to see some exciting science taking place at this ground-breaking facility.”

    LZ will be at least 100 times more sensitive to finding signals from dark matter particles than its predecessor, the Large Underground Xenon experiment (LUX). The new experiment will use 10 metric tons of ultra-purified liquid xenon, to tease out possible dark matter signals. Xenon, in its gas form, is one of the rarest elements in Earth’s atmosphere.

    Although this is a major milestone for the experiment, there are still many components yet to be assembled and tested. Upgrades of the underground Davis cavern at SURF, where LZ will be installed, are in progress and will be completed by August and large acrylic tanks that will help to validate LZ measurements are expected to arrive at SURF by September. It is currently expected that the experiment will start taking data in 2020.

    The U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) is leading the LZ project, which is expected to be completed in 2020. About 200 scientists and engineers from 39 institutions around the globe are part of the LZ collaboration.

    Since the project’s inception in 2012, STFC has been in charge of the design and the delivery of the cryostat. The engineering effort has been led by Joseph Saba, a Berkeley Lab mechanical engineer, and Edward Holtom of STFC’s Technology Department.

    Majewski said, “The cryostat was a feat of engineering, with some very stringent and challenging requirements. Because of its huge mass (about 2.2 tons), we had to make sure it was made of ultrapure titanium or it would overwhelm the detector with background radiation. It took more than two years to find titanium pure enough to work with.”

    He added, “This type of ultrapure titanium is used, for example, in the health care industry to fabricate pacemaker encapsulations. In our case it is used to hold the heart of the experiment.”

    The cryostat is the U.K.’s largest contribution to LZ but is not the only contribution. STFC is also supporting work on LZ’s calibration hardware, photomultiplier tubes, internal monitoring sensors, and materials screening, and is supporting one of the LZ data centers.

    Professor Henrique Araújo of Imperial College London, who is the U.K.’s principal investigator for LZ, said, “It is incredibly gratifying to see LZ beginning to take shape. Seeing the cryostat arrive is a milestone moment as it has been years in the making. This is the first big piece around which we will build the rest of the experiment.”

    There are still many LZ components yet to be assembled and tested. The experiment is expected to start taking data in 2020.

    Upgrades of the underground Davis cavern at SURF, where LZ will be installed, are in progress and will be completed by August, Gilchriese said, and large acrylic tanks that will help to validate LZ measurements are expected to arrive at SURF by September.

    Major support for LZ comes from the DOE Office of Science, the South Dakota Science and Technology Authority, the UK’s Science & Technology Facilities Council, and by collaboration members in South Korea and Portugal.

    See the full STFC article here.
    See the full LBNL article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    STFC Hartree Centre

    Helping build a globally competitive, knowledge-based UK economy

    We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

    Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
    Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
    National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
    Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

    We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

    STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

    Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

    They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

    Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

    The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

    We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

    Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

     
  • richardmitnick 3:58 pm on November 1, 2017 Permalink | Reply
    Tags: , , , , , Dark Matter Research, , Physicists describe new dark matter detection strategy,   

    From Brown: “Physicists describe new dark matter detection strategy” 

    Brown University
    Brown University

    November 1, 2017
    Kevin Stacey
    401-863-3766

    Physicists from Brown University have devised a new strategy for directly detecting dark matter, the elusive material thought to account for the majority of matter in the universe.

    1
    Superfluid dark matter catcher
    A proposed dark matter detector using superfluid helium might detect particles with much lower mass than most current detectors.
    Maris/Seidel/Stein/Brown University

    The new strategy, which is designed to detect interactions between dark matter particles and a tub of superfluid helium, would be sensitive to particles in a much lower mass range than is possible with any of the large-scale experiments run so far, the researchers say.

    “Most of the large-scale dark matter searches so far have been looking for particles with a mass somewhere between 10 and 10,000 times the mass of a proton,” said Derek Stein, a physicist who co-authored the work with two of his Brown University colleagues, Humphrey Maris and George Seidel. “Below 10 proton masses, these experiments start to lose their sensitivity. What we want to do is extend sensitivity down in mass by three or four orders of magnitude and explore the possibility of dark matter particles that are much lighter.”

    A paper describing the new detector is published in Physical Review Letters.

    Missing matter

    Though it has not yet been detected directly, physicists are fairly certain that dark matter must exist in some form. The way in which galaxies rotate and the degree to which light bends as it travels through the universe suggest that there’s some kind of unseen stuff throwing its gravity around.

    The leading idea for the nature of dark matter is that it’s some kind of particle, albeit one that interacts very rarely with ordinary matter. But nobody is quite sure what a dark matter particle’s properties might be because nobody has yet recorded one of those rare interactions.

    There’s been good reason, Stein says, to search in the mass range where most dark matter experiments have focused thus far. A particle in that mass range would tie up a lot of loose theoretical ends. For example, the theory of supersymmetry — the idea that all the common particles we know and love have hidden partner particles — predicts dark matter candidates of the order of hundreds of proton masses.

    But the no-show of those particles in experiments so far has some physicists thinking about how to look elsewhere. This has led theorists to propose models in which dark matter would have much lower mass.

    A new approach

    The detection strategy that the Brown researchers have come up with involves a tub of superfluid helium. The idea is that dark matter particles passing through the tub should, on very rare occasions, smack into the nucleus of a helium atom. That collision would produce phonons and rotons — tiny excitations roughly similar to sound waves — which propagate with no loss of kinetic energy inside the superfluid. When those excitations reach the surface of the fluid, they’ll cause helium atoms to be released into a vacuum space above the surface. The detection of those released atoms would be the signal that a dark matter interaction has taken place in the tub.

    “The last bit is the tricky part,” said Maris, who has worked on similar helium-based detection schemes for other particles like solar neutrinos. The collision of a low-mass dark matter particle might result in only a single atom being released from the surface. That single atom would carry only about one milli-electron volt of energy, making it virtually impossible to detect through any traditional means. The novelty of this new detection scheme is a means to amplify that tiny, single-atom energy signature.

    It works by generating an electric field in the vacuum space above the liquid using an array of small, positively charged metal pins. As an atom released from the helium surface draws close to a pin, the positively charged tip will steal an electron from it, creating a positively charged helium ion. That newly created positive ion would be in close proximity to the positively charged pin, and because like charges repel each other, the ion will fly off with enough energy to be easily detectable by a standard calorimeter, a device that detects a temperature change when a particle runs into it.

    “If we put 10,000 volts on those little pins, then that ion going is going to fly away with 10,000 volts on it,” Maris said. “So it’s this ionization feature that gives us a new way to detect just the single helium atom that could be associated with a dark matter interaction.”

    Sensitive at low mass

    This new kind of detector wouldn’t be the first to use the tub-of-liquid-gas idea. The recently completed Large Underground Xenon (LUX) experiment and its successor, LUX-ZEPLIN, both use tubs of xenon gas. Using helium instead provides an important advantage in looking for particles with lower mass, the researchers say.

    For a collision to be detectable, the incoming particle and the target atomic nuclei must be of compatible mass. If the incoming particle is much smaller in mass than the target nuclei, any collision would result in the particle simply bouncing off without leaving a trace. Since LUX and L-Z are intended for the detection of particles with mass greater than five times that of a proton, they used xenon, which has a nucleus of around 100 proton masses. Helium has a nuclear mass only four times that of a proton, making a more compatible target for particles with much less mass.

    But even more important than the light target, the researchers say, is the ability of the new scheme to detect only a single atom evaporated from the helium surface. That kind of sensitivity would enable the device to detect the tiny amounts of energy deposited in the detector by particles with very small masses. The Brown team thinks its device would be sensitive to masses down to about twice the mass of an electron, roughly 1,000 to 10,000 times lighter than the particles detectable in large-scale dark matter experiments so far.

    Stein says that the first steps in actually making such a detector a reality will be fundamental experiments to better understand aspects of what’s happening in the superfluid helium and the precise dynamics of the ionization scheme.

    “From those fundamental experiments,” Stein says, “we would craft designs for a bigger and more complete dark matter experiment.”

    The research was funded in part by the National Science Foundation (DMR-1505044).

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
  • richardmitnick 3:49 pm on October 26, 2017 Permalink | Reply
    Tags: , , , , Dark Matter Research, , ,   

    From The Conversation: “Dark matter: The mystery substance physics still can’t identify that makes up the majority of our universe” 

    FNAL II photo

    Fermilab

    Conversation
    The Conversation

    10.25.17
    Dan Hooper

    1
    Astronomers map dark matter indirectly, via its gravitational pull on other objects. NASA, ESA, and D. Coe (NASA JPL/Caltech and STScI), CC BY

    The past few decades have ushered in an amazing era in the science of cosmology. A diverse array of high-precision measurements has allowed us to reconstruct our universe’s history in remarkable detail.

    And when we compare different measurements – of the expansion rate of the universe, the patterns of light released in the formation of the first atoms, the distributions in space of galaxies and galaxy clusters and the abundances of various chemical species – we find that they all tell the same story, and all support the same series of events.

    This line of research has, frankly, been more successful than I think we had any right to have hoped. We know more about the origin and history of our universe today than almost anyone a few decades ago would have guessed that we would learn in such a short time.

    But despite these very considerable successes, there remains much more to be learned. And in some ways, the discoveries made in recent decades have raised as many new questions as they have answered.

    One of the most vexing gets at the heart of what our universe is actually made of. Cosmological observations have determined the average density of matter in our universe to very high precision. But this density turns out to be much greater than can be accounted for with ordinary atoms.

    After decades of measurements and debate, we are now confident that the overwhelming majority of our universe’s matter – about 84 percent – is not made up of atoms, or of any other known substance. Although we can feel the gravitational pull of this other matter, and clearly tell that it’s there, we simply do not know what it is. This mysterious stuff is invisible, or at least nearly so. For lack of a better name, we call it “dark matter.” But naming something is very different from understanding it.

    For almost as long as we’ve known that dark matter exists, physicists and astronomers have been devising ways to try to learn what it’s made of. They’ve built ultra-sensitive detectors, deployed in deep underground mines, in an effort to measure the gentle impacts of individual dark matter particles colliding with atoms.

    They’ve built exotic telescopes – sensitive not to optical light but to less familiar gamma rays, cosmic rays and neutrinos – to search for the high-energy radiation that is thought to be generated through the interactions of dark matter particles.

    And we have searched for signs of dark matter using incredible machines which accelerate beams of particles – typically protons or electrons – up to the highest speeds possible, and then smash them into one another in an effort to convert their energy into matter. The idea is these collisions could create new and exotic substances, perhaps including the kinds of particles that make up the dark matter of our universe.

    As recently as a decade ago, most cosmologists – including myself – were reasonably confident that we would soon begin to solve the puzzle of dark matter. After all, there was an ambitious experimental program on the horizon, which we anticipated would enable us to identify the nature of this substance and to begin to measure its properties. This program included the world’s most powerful particle accelerator – the Large Hadron Collider – as well as an array of other new experiments and powerful telescopes.

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    2
    Experiments at CERN are trying to zero in on dark matter – but so far no dice. CERN, CC BY-ND

    But things did not play out the way that we expected them to. Although these experiments and observations have been carried out as well as or better than we could have hoped, the discoveries did not come.

    Over the past 15 years, for example, experiments designed to detect individual particles of dark matter have become a million times more sensitive, and yet no signs of these elusive particles have appeared. And although the Large Hadron Collider has by all technical standards performed beautifully, with the exception of the Higgs boson, no new particles or other phenomena have been discovered.

    3
    At Fermilab, the Cryogenic Dark Matter Search uses towers of disks made from silicon and germanium to search for particle interactions from dark matter. Reidar Hahn/Fermilab, CC BY

    The stubborn elusiveness of dark matter has left many scientists both surprised and confused. We had what seemed like very good reasons to expect particles of dark matter to be discovered by now. And yet the hunt continues, and the mystery deepens.

    In many ways, we have only more open questions now than we did a decade or two ago. And at times, it can seem that the more precisely we measure our universe, the less we understand it. Throughout the second half of the 20th century, theoretical particle physicists were often very successful at predicting the kinds of particles that would be discovered as accelerators became increasingly powerful. It was a truly impressive run.

    But our prescience seems to have come to an end – the long-predicted particles associated with our favorite and most well-motivated theories have stubbornly refused to appear. Perhaps the discoveries of such particles are right around the corner, and our confidence will soon be restored. But right now, there seems to be little support for such optimism.

    In response, droves of physicists are going back to their chalkboards, revisiting and revising their assumptions. With bruised egos and a bit more humility, we are desperately attempting to find a new way to make sense of our world.

    See the full article here .

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    Stem Education Coalition

    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 10:48 am on October 17, 2017 Permalink | Reply
    Tags: Carleton U, Dark Matter Research, DEAP-3600 experiment, Ottawa Citizen,   

    From Carleton U via Ottawa Citizen: “Dark matter: Carleton physicist gets $3.35M to help unravel mysteries of the universe” 

    Carleton University
    1
    Carleton University experimental physicist Mark Boulay has been warded $3.35 million for a new lab. Tony Caldwell

    A Carleton University experimental physicist has been awarded $3.35 million to build a lab to help gain insight into the nature of neutrinos and dark matter. The elusive answers to those questions could lead to nothing less than a better understanding of how the universe was formed.

    Neutrinos are much smaller than other known particles, and are very difficult to detect. The actually mass of the neutrino is not known. A measurement that would shed light on its mass and the origin of that mass would offer some insight into the formation of the universe.

    Dark matter is even more mysterious.

    Dark Matter Research

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

    Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

    Dark Matter Particle Explorer China

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

    LUX Dark matter Experiment at SURF, Lead, SD, USA

    ADMX Axion Dark Matter Experiment, U Uashington

    It has never been observed, but scientists have known for a long time that it’s out there because its gravitational effects can be seen — galaxies move faster than expected, for example.

    Dark matter outweighs conventional matter by five-to-one, said Mark Boulay, who is the Canada Research Chair in Particle Astrophysics and Subatomic Physics. Essentially, most of the matter in the universe is invisible.

    “There’s a large amount of mass that goes unaccounted for. We know that there’s matter out there, but we haven’t directly seen it,” he said.

    The $3.35 million in funding from the Canada Foundation for Innovation will be used to develop and build detectors that use liquified noble gases to identify extremely rare subatomic processes.

    Boulay has been leading the DEAP-3600 experiment in SNOLAB, an underground laboratory in a mine two kilometres under the surface of the earth near Sudbury.

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

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

    One hypothesis suggests that dark matter consists of Weakly Interacting Massive Particles, known as WIMPs. The rock overburden at SNOLAB filters out cosmic rays that would interfere with WIMP detection. The DEAP-3600 experiments searches for dark matter particle interactions using a detector containing 3,600 kilograms of liquid argon.

    Dark matter research is one of the highest-profile areas of particle physics — and it’s highly competitive. The detectors being developed for the Carleton lab will support the study of neutrinos and dark matter at SNOLAB. The lab will be used by researchers at Carleton and others in its network, which includes TRIUMF, Canada’s national laboratory for particle and nuclear physics, as well as the University of British Columbia, McGill University and Université de Sherbrooke.

    “In my field we’ve been looking to demonstrate conclusively the existence of this particle. We’ve been looking for two or three decades. We haven’t found it yet. We don’t know what the mass of the particle is, or how likely it is to interact with other matter,” said Boulay. “We understand that we have a lot of work ahead of us.”

    He estimates it will take a year to construct the first set of prototype detectors for the lab at Carleton. The lab will occupy about 2,000 square feet of space in the Herzberg building.

    “We want to be able to define future programs — what detectors we will be able to build in the next 20 years,” said Boulay. “We’re at the leading edge of what’s possible, and we want to push that.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Situated on unceded Algonquin territory beside the historic Rideau Canal, an official UNESCO World Heritage Site, Carleton University was founded by the community in 1942 to meet the needs of veterans returning from the Second World War.

    What defines Carleton?

    We strive for innovation in research, teaching and learning.
    Our location in Ottawa, the nation’s capital, connects us to the world.
    We encourage hands-on experience in the classroom.
    We offer exceptional student support.

     
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