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  • richardmitnick 9:37 am on October 12, 2021 Permalink | Reply
    Tags: "Is dark matter cold or warm or hot?", , , , , , , , , Theoretical Physics,   

    From Symmetry: “Is dark matter cold or warm or hot?” 

    Symmetry Mag

    From Symmetry

    10/12/21
    Glennda Chui

    The answer has to do with dark matter’s role in shaping the cosmos.

    Milky Way Dark Matter Halo Credit:L. Calçada/ European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte](EU)(CL)

    Half a century after Vera Rubin and Kent Ford confirmed that a form of invisible matter—now called dark matter—is required to account for the rotation of galaxies, the evidence for its existence is overwhelming.
    _____________________________________________________________________________________
    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

    Dark Matter Research

    Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
    _____________________________________________________________________________________

    Although it is known to interact with ordinary matter only through gravity, there is such a massive amount of dark matter out there—85% of all the matter in the universe—that it has played a pivotal behind-the-scenes role in shaping all the stuff we can see, from our own Milky Way galaxy to the wispy filaments of gas that link galaxies across vast distances.

    “We think it exists because there’s evidence for it on many, many scales,” says Kevork Abazajian, a theoretical physicist and astrophysicist at The University of California-Irvine (US).

    There have been a lot of ideas about what form dark matter might take, from planet-sized objects called MACHOs to individual particles like WIMPs—weakly interacting massive particles roughly the size of a proton—and even tinier things like axions and sterile neutrinos.

    In the 1980s, scientists came up with a way to make sense of this growing collection: They started classifying proposed dark-matter particles as cold, warm or hot. These categories are based on how fast each type of dark matter would have traveled through the early universe—a speed that depended on its mass—and on how hot its surroundings were when it popped into existence.

    Light, fast particles are known as hot dark matter; heavy, slow ones are cold dark matter; and warm dark matter falls in between.

    In this way of seeing things, WIMPs are cold, sterile neutrinos are warm, and relic neutrinos from the early universe are hot. (Axions are a special case—both light and extremely cold. We’ll get to them later.)

    Why is their speed so important?

    “If a dark matter particle is lighter and faster, it can travel farther in a given time, and it will smooth out any structure that already exists along the way,” Abazajian says.

    On the other hand, slower, colder forms of dark matter would have helped build structure, and based on what we know and see today it must have been part of the mix.

    Building galaxies

    Although there are theories about when and how each type of dark-matter candidate would have formed, the only thing scientists know for sure is that dark matter was already around about 75,000 years after the Big Bang. It was then that matter started to dominate over radiation and little seeds of structure started to form, says Stanford University (US) theoretical physicist Peter Graham.

    Most types of dark-matter particles would have been created by collisions between other particles in the hot, dense soup of the infant universe, in much the same way that high-energy particle collisions at places like the Large Hadron Collider give rise to exotic new types of particles. As the universe expanded and cooled, dark-matter particles would have wound up being hot, warm or cold—and, in fact, there could have been more than one type.

    Scientists describe them as freely “streaming” through the universe, although this term is a little misleading, Abazajian says. Unlike leaves floating on a river, all headed in the same direction in a coordinated way, “these things are not just in one place and then in another place,” he says. “They’re everywhere and going in every direction.”

    As it streamed, each type of dark matter would have had a distinctive impact on the growth of structure along the way—either adding to its clumpiness, and thus to the building of galaxies, or thwarting their growth.

    Cold dark matter, such as the WIMP, would have been a clump-builder. It moved slowly enough to glom together and form gravitational wells, which would have captured nearby bits of matter.

    Hot dark matter, on the other hand, would have been a clump-smoother, zipping by so fast that it could ignore those gravitational wells. If all dark matter were hot, none of those seeds could have grown into bigger structures, says Silvia Pascoli, a theoretical physicist at The University of Bologna [Alma mater studiorum – Università di Bologna](IT). That’s why scientists now believe that hot dark-matter particles, such as relic neutrinos from the early days of the cosmos, could not constitute more than a sliver of dark matter as a whole.

    Despite their tiny contribution, Pascoli adds, “I say these relic neutrinos are currently the only known component of dark matter. They have an important impact on the evolution of the universe.”

    You might think that warm dark matter would be the best dark matter, filling the universe with a Goldilocks bowl of just-right structure. Sterile neutrinos are considered the top candidate in this category, and in theory they could indeed constitute the vast majority of dark matter.

    But most of the parameter space—the sets of conditions—where they could exist have been ruled out, says Abazajian, who as a graduate student researched how specific types of neutrino oscillations in the early universe could have produced sterile neutrino dark matter.

    Although those same oscillations could be happening today, he says, the probability that a regular neutrino would turn into a sterile one through standard oscillations in the vacuum of space are thought to be very small, with estimates ranging from 1 in 100,000 to 1 in 100 trillion.

    “You’d have to have a very good counting mechanism to count up to 100 trillion hits in your detector without missing the one hit from a sterile neutrino,” Abazajian says.

    That said, there are a few experiments out there that are giving it a try, using new approaches that don’t rely on direct hits.

    Then there’s the axion.

    Unlike the other dark-matter candidates, axions would be both extremely light—so light that they are better described as waves whose associated fields can spread over kilometers—and extremely cold, Graham says. They are so weakly coupled to other forms of matter that the frantic collisions of particles in the thermal bath of the early universe would have produced hardly any.

    “They would have been produced in a different way than the other dark matter candidates,” Graham says. “Even though the universe was very hot at the time, axions would have been very cold at birth and would stay cold forever, which means that they are absolutely cold dark matter.”

    Even though axions are very light, Graham says, “because they exist at close to absolute zero, the temperature where all motion stops, they are essentially not moving. They’re kind of this ghostly fluid, and everything else moves through it.”

    Searching for dark matter of all kinds

    Some scientists think it will take more than one type of dark matter to account for all the things we see in the universe.

    And in the past few years, as experiments aimed at detecting WIMPs and producing dark matter particles through collisions at the Large Hadron Collider have so far come up empty-handed, the search for dark matter has broadened.

    SixTRack CERN LHC particles

    The proliferation of ideas for searches has been helped by technological advances and clever approaches that could force much lighter and even more exotic dark-matter particles out of hiding.

    Some of those efforts make use of the very clumpiness that dark matter was instrumental in creating.

    Simona Murgia, an experimentalist at The University of California-Irvine (US), led a team looking for signs of collisions between WIMPs and their antiparticles with the Fermi Gamma-ray Space Telescope while a postdoc at the DOE’s SLAC National Accelerator Laboratory.

    Now she’s joined an international team of scientists who will conduct a vast survey of the Southern sky from the Vera C. Rubin Observatory in Chile using the world’s biggest digital camera, which is under construction at SLAC.

    NSF (US) NOIRLab (US) NOAO (US) Vera C. Rubin Observatory [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 NSF (US) NOIRLab (US) NOAO (US) AURA (US) Gemini South Telescope and Southern Astrophysical Research Telescope.

    One of the things this survey will do is get a much better handle on the distribution of dark matter in the universe by looking at how it bends light from the galaxies we can see.

    “It will tell us something about the nature of dark matter in a totally different way,” Murgia says. “The more clumpy its distribution is, the more consistent it is with theories that tell you dark matter is cold.”

    The camera is expected to snap images of about 20 billion galaxies over 10 years, and from those images scientists hope to infer the fundamental nature of the dark matter that shaped them.

    “We don’t only want to know the dark matter is there,” Murgia says. “We do want to understand the cosmology, but we also really want to know what dark matter is.”

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 9:52 pm on October 11, 2021 Permalink | Reply
    Tags: , , , Theoretical Physics, , "The Search for Quantum Gravity"   

    From The University of California-Santa Barbara (US) : “The Search for Quantum Gravity” 

    UC Santa Barbara Name bloc

    From The University of California-Santa Barbara (US)

    October 11, 2021

    Sonia Fernandez
    sonia.fernandez@ucsb.edu

    With support from The Heising-Simons Foundation (US), theoretical physicists take a new approach to the search for quantum gravity.

    1
    Quantum Gravity Illustration

    About a century ago, Albert Einstein amazed the world with his groundbreaking theory of relativity, and ever since he shared this profound understanding of gravity and spacetime, physicists everywhere have worked hard to prove, refine and extend it. In the intervening decades, numerous observations have borne Einstein out, with phenomena such as gravitational lensing and redshift, shifts in planetary orbit and, more recently, gravitational waves and observations of black holes.

    However, for all the advances we’ve made in witnessing the more readily observable, macro effects of gravity, there remains a gap — a chasm, really — in our ability to understand gravity in the context of another profound discovery: quantum mechanics, the physics of matter and energy at their smallest scales.

    “There is the longstanding problem, perhaps the greatest remaining from 20th century physics, of reconciling quantum mechanics with gravity,” said UC Santa Barbara theoretical physicist Steven Giddings. The universe is quantum, and unlike the other fundamental forces — the electromagnetic, the weak and the strong nuclear forces — which have been described within quantum field theory, what we know of gravitation remains solidly in the realm of classical physics.

    “Associated with that problem is a gulf between theory and observation,” said Giddings, who specializes in high energy and gravitational theory, as well as quantum black holes, quantum cosmology and other quantum aspects of gravity. Traditional thinking leads one to believe that quantum aspects of gravity are only observable if we explore incredibly short distances, he said, such as the Planck length (10-35 meter), thought to be the smallest length in the universe and the length at which quantum gravity effects become important. It’s also far beyond observational reach.

    But what if it was possible to detect quantum gravity at longer, observable length scales? Giddings, and fellow theorists Kathryn Zurek and Yanbei Chen at The California Institute of Technology (US), Cynthia Keeler and Maulik Parikh at The Arizona State University (US), and Ben Freivogel and Erik Verlinde at The University of Amsterdam [Universiteit van Amsterdam](NL), think that could be the case.

    “Various theoretical developments have indicated that quantum gravity effects may become important at much greater distances in certain contexts, and that is truly exciting and worth exploring,” Giddings said. “We are taking this seriously.”

    And, thanks to support from the Heising-Simons Foundation, the team is poised to bridge that chasm, by exploring ways in which quantum gravity may be observed, via effects a longer length scales.

    “We are thrilled that the Heising-Simons Foundation has chosen to support this vision of exploring new effects, particularly at long distances, in quantum gravity, and the possibility that they lead to observational effects,” Giddings said of the $3.1 million in multi-institution grants to help the team push the boundaries of our knowledge of quantum gravity. “Their support should really move this research forward.”

    Quantum Effects at Longer Lengths

    Reconciling relativity to quantum mechanics has challenged physicists for the better part of a century, with puzzles such as the black hole information paradox. That’s where relativity and quantum mechanics violently conflict on the issue of what happens to information that falls into a black hole, those extremely high-gravity voids in spacetime. A relativistic picture indicates that the information gets destroyed as the black hole slowly evaporates, while quantum mechanics states that that information cannot be destroyed.

    A suggested approach to that conundrum and other similarly complex issues emerges with the proposed holographic principle, a fundamentally new idea about the possible behavior of quantum gravity.

    “There are different ways to explain it, but one is that the amount of information you can put in a volume is not proportional to the volume but to the surface area surrounding the volume,” Giddings explained. A consistent theory incorporating this principle might explain how information is not destroyed, resulting in a relativistic object, such as a black hole, obeying quantum rules.

    “When one tries to reconcile the existence of black holes with the principles of quantum mechanics, one seems to be led to the conclusion that new quantum gravity effects must become important not just at short distances, but at distances comparable to the size of the black hole in question — for the largest black holes we know, many times the size of our solar system,” Giddings said.

    The principle, which started out originally with black holes, has been suggested to extend to the universe in general — what we perceive as our three-dimensional reality may even, in a sense, have an underlying two-dimensional description. This could make its mathematical description more elegant and compelling.

    “This is a big departure from the properties of quantum field theories that describe other forces of nature — like electromagnetism and the strong force — and is a feature of gravity that strongly suggests that a theory of gravity has a very different underlying structure,” he added. This fundamentally different structure might be part of a description with novel properties, in which information is preserved.

    A related argument for the observability of quantum gravity at greater distances comes from the notion that very high energy collisions, though far beyond what we have been able to accomplish, start producing quantum gravitational effects at increasingly large distances.

    “When one considers extremely high energy collisions of particles, one is not probing shorter distances any longer — as has been true at accessible energies — but instead one starts to see effects at longer distances, due to basic properties of gravity,” Giddings said.

    Quantum Gravity at Work

    Recent developments in experimental observations have made it possible to detect and measure new effects of gravity, such as with Caltech’s Laser Interferometer Gravitational Wave Observatory (LIGO), the Virgo interferometer in Italy, and the Kamioka Gravitational Wave Detector (KAGRA) in Japan.

    _______________________________________________________________________________________
    LIGOVIRGOKAGRA

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

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    KAGRA Large-scale Cryogenic Gravitational Wave Telescope Project (JP)
    _______________________________________________________________________________________
    Each of those facilities is turned to space to sense gravitational waves coming from major events, such as the mergers of massive celestial bodies like black holes and neutron stars. These, as well as observations of light from near black holes by The Event Horizon Telescope-EHT, may also be sensitive to long-range quantum effects. In addition, ideas related to holography suggest the possibility of new quantum effects in lab-based settings, and newer experiments with interferometers may provide novel ways to test them.

    The task for the researchers as they resolve foundational issues and understand aspects of the fundamental description of quantum gravity, is to develop “effective descriptions” that can connect theory with observations coming in from the interferometers and other instruments.

    “In physics, we have often been in the situation where we don’t have the complete theory, but we have an approximate description that captures certain important properties of that theory,” Giddings explained. “Often, such ‘effective descriptions’ can be surprisingly powerful, and lead to deeper insight about the more fundamental theory.”

    The group’s diverse mix of backgrounds is a strength of this collaboration, with specializations ranging from quantum gravity to particle physics, string theory to gravitational wave physics. Through a series of meetings to be held over four years the collaboration will progress from foundational issues, such as sharpening the description of holography and understanding the mathematical structure of gravity, to studying models that may describe behavior of quantum gravity, its interactions and potentially observable effects, to developing specific observational tests with the interferometers and observations of black holes.

    Along the way, the collaboration will grow, starting with the seven core members and adding postdoctoral fellows and graduate students, and finally broadening activities to include additional physicists to discuss collaboration results and related theoretical advances from the broader community.

    “If we are able to observe quantum effects of black holes, that will be truly revolutionary,” Giddings said. “It would also likely help guide the conceptual revolution of reconciling quantum mechanics with gravity, which we expect to likely be as profound as the revolutionary discovery of quantum mechanics.”

    See the full article here .


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    UC Santa Barbara Seal

    The University of California-Santa Barbara (US) is a public land-grant research university in Santa Barbara, California, and one of the ten campuses of the University of California (US) system. Tracing its roots back to 1891 as an independent teachers’ college, The University of California-Santa Barbara joined the University of California system in 1944, and is the third-oldest undergraduate campus in the system.

    The university is a comprehensive doctoral university and is organized into five colleges and schools offering 87 undergraduate degrees and 55 graduate degrees. It is classified among “R1: Doctoral Universities – Very high research activity”. According to the National Science Foundation (US), The University of California-Santa Barbara spent $235 million on research and development in fiscal year 2018, ranking it 100th in the nation. In his 2001 book The Public Ivies: America’s Flagship Public Universities, author Howard Greene labeled The University of California-Santa Barbara a “Public Ivy”.

    The University of California-Santa Barbara is a research university with 10 national research centers, including the Kavli Institute for Theoretical Physics (US) and the Center for Control, Dynamical-Systems and Computation. Current University of California-Santa Barbara faculty includes six Nobel Prize laureates; one Fields Medalist; 39 members of the National Academy of Sciences (US); 27 members of the National Academy of Engineering (US); and 34 members of the American Academy of Arts and Sciences (US). The University of California-Santa Barbara was the No. 3 host on the ARPANET and was elected to the Association of American Universities in 1995. The faculty also includes two Academy and Emmy Award winners and recipients of a Millennium Technology Prize; an IEEE Medal of Honor; a National Medal of Technology and Innovation; and a Breakthrough Prize in Fundamental Physics.
    The University of California-Santa Barbara Gauchos compete in the Big West Conference of the NCAA Division I. The Gauchos have won NCAA national championships in men’s soccer and men’s water polo.

    History

    The University of California-Santa Barbara traces its origins back to the Anna Blake School, which was founded in 1891, and offered training in home economics and industrial arts. The Anna Blake School was taken over by the state in 1909 and became the Santa Barbara State Normal School which then became the Santa Barbara State College in 1921.

    In 1944, intense lobbying by an interest group in the City of Santa Barbara led by Thomas Storke and Pearl Chase persuaded the State Legislature, Gov. Earl Warren, and the Regents of the University of California to move the State College over to the more research-oriented University of California system. The State College system sued to stop the takeover but the governor did not support the suit. A state constitutional amendment was passed in 1946 to stop subsequent conversions of State Colleges to University of California campuses.

    From 1944 to 1958, the school was known as Santa Barbara College of the University of California, before taking on its current name. When the vacated Marine Corps training station in Goleta was purchased for the rapidly growing college Santa Barbara City College moved into the vacated State College buildings.

    Originally the regents envisioned a small several thousand–student liberal arts college a so-called “Williams College (US) of the West”, at Santa Barbara. Chronologically, The University of California-Santa Barbara is the third general-education campus of the University of California, after The University of California-Berkeley (US) and The University of California-Los Angeles (US) (the only other state campus to have been acquired by the UC system). The original campus the regents acquired in Santa Barbara was located on only 100 acres (40 ha) of largely unusable land on a seaside mesa. The availability of a 400-acre (160 ha) portion of the land used as Marine Corps Air Station Santa Barbara until 1946 on another seaside mesa in Goleta, which the regents could acquire for free from the federal government, led to that site becoming the Santa Barbara campus in 1949.

    Originally only 3000–3500 students were anticipated but the post-WWII baby boom led to the designation of general campus in 1958 along with a name change from “Santa Barbara College” to “University of California-Santa Barbara,” and the discontinuation of the industrial arts program for which the state college was famous. A chancellor- Samuel B. Gould- was appointed in 1959.

    In 1959 The University of California-Santa Barbara professor Douwe Stuurman hosted the English writer Aldous Huxley as the university’s first visiting professor. Huxley delivered a lectures series called The Human Situation.

    In the late ’60s and early ’70s The University of California-Santa Barbara became nationally known as a hotbed of anti–Vietnam War activity. A bombing at the school’s faculty club in 1969 killed the caretaker Dover Sharp. In the spring of 1970 multiple occasions of arson occurred including a burning of the Bank of America branch building in the student community of Isla Vista during which time one male student Kevin Moran was shot and killed by police. The University of California-Santa Barbara ‘s anti-Vietnam activity impelled then-Gov. Ronald Reagan to impose a curfew and order the National Guard to enforce it. Armed guardsmen were a common sight on campus and in Isla Vista during this time.

    In 1995 The University of California-Santa Barbara was elected to the Association of American Universities– an organization of leading research universities with a membership consisting of 59 universities in the United States (both public and private) and two universities in Canada.

    On May 23, 2014 a killing spree occurred in Isla Vista, California, a community in close proximity to the campus. All six people killed during the rampage were students at The University of California-Santa Barbara. The murderer was a former Santa Barbara City College student who lived in Isla Vista.

    Research activity

    According to the National Science Foundation (US), The University of California-Santa Barbara spent $236.5 million on research and development in fiscal 2013, ranking it 87th in the nation.

    From 2005 to 2009 UCSB was ranked fourth in terms of relative citation impact in the U.S. (behind Massachusetts Institute of Technology (US), California Institute of Technology(US), and Princeton University (US)) according to Thomson Reuters.

    The University of California-Santa Barbara hosts 12 National Research Centers, including the Kavli Institute for Theoretical Physics, the National Center for Ecological Analysis and Synthesis, the Southern California Earthquake Center, the UCSB Center for Spatial Studies, an affiliate of the National Center for Geographic Information and Analysis, and the California Nanosystems Institute. Eight of these centers are supported by The National Science Foundation (US). UCSB is also home to Microsoft Station Q, a research group working on topological quantum computing where American mathematician and Fields Medalist Michael Freedman is the director.

    Research impact rankings

    The Times Higher Education World University Rankings ranked The University of California-Santa Barbara 48th worldwide for 2016–17, while the Academic Ranking of World Universities (ARWU) in 2016 ranked https://www.nsf.gov/ 42nd in the world; 28th in the nation; and in 2015 tied for 17th worldwide in engineering.

    In the United States National Research Council rankings of graduate programs, 10 University of California-Santa Barbara departments were ranked in the top ten in the country: Materials; Chemical Engineering; Computer Science; Electrical and Computer Engineering; Mechanical Engineering; Physics; Marine Science Institute; Geography; History; and Theater and Dance. Among U.S. university Materials Science and Engineering programs, The University of California-Santa Barbara was ranked first in each measure of a study by the National Research Council of the NAS.

    The Centre for Science and Technologies Studies at

     
  • richardmitnick 1:47 pm on October 8, 2021 Permalink | Reply
    Tags: "Fermilab boasts new Theory Division", Astrophysics Theory, , , , , , , Fermilab experts on perturbative QCD use high-performance computing to tackle the complexity of simulations for experiments at the Large Hadron Collider., Muon g-2 Theory Initiative and the Muon g-2 experiment, , Particle Theory, , , Superconducting Systems, Theoretical Physics   

    From DOE’s Fermi National Accelerator Laboratory (US) : “Fermilab boasts new Theory Division” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From DOE’s Fermi National Accelerator Laboratory (US) , an enduring source of strength for the US contribution to scientific research worldwide.

    October 8, 2021

    Theoretical physics research at Fermi National Particle Accelerator Laboratory has always sparked new ideas and scientific opportunities, while at the same time supporting the large experimental group that conducts research at Fermilab. In recent years, the Theoretical Physics Department has further strengthened its position worldwide as a hub for the high-energy physics theoretical community. The department has now become Fermilab’s newest division, the Theory Division, which officially launched early this year with strong support from HEP.

    This new division seeks to:

    support strategic theory leadership;
    promote new initiatives, as well as strengthen existing ones;
    and leverage U.S. Department of Energy support through partnerships with universities and more.

    “Creating the Theory Division increases the lab’s abilities to stimulate and develop new pathways to discovery,” said Fermilab Director Nigel Lockyer.

    Led by Marcela Carena and her deputy Patrick Fox, this new division features three departments: Particle Theory, Astrophysics Theory and Quantum Theory. “This structure will help us focus our scientific efforts in each area and will allow for impactful contributions to existing and developing programs for the theory community,” said Carena.

    Particle Theory Department

    At the helm of the Particle Theory Department is Andreas Kronfeld. This department studies all aspects of theoretical particle physics, especially those areas inspired by the experimental program—at Fermilab and elsewhere. It coordinates leading national efforts, including the Neutrino Theory Network, and the migration of the lattice gauge theory program to Exascale computing platforms. Lattice quantum chromodynamics, or QCD, experts support the Muon g-2 Theory Initiative, providing a solid theory foundation for the recently announced results of the Muon g-2 experiment.

    Fermilab particle theorists, working with DOE’s Argonne National Laboratory (US) nuclear theorists, are using machine learning for developing novel event generators to precisely model neutrino-nuclear interactions, and employ lattice QCD to model multi-nucleon interactions; both are important for achieving the science goals of DUNE.

    Fermilab experts on perturbative QCD use high-performance computing to tackle the complexity of simulations for experiments at the Large Hadron Collider. Fermilab theorists are strongly involved in the exploration of physics beyond the Standard Model, through model-building, particle physics phenomenology, and formal aspects of quantum field theory.

    Astrophysics Theory Department

    Astrophysics Theory, led by Dan Hooper, consists of researchers who work at the confluence of astrophysics, cosmology and particle physics. Fermilab’s scientists have played a key role in the development of this exciting field worldwide and continue to be deeply involved in supporting the Fermilab cosmic frontier program.

    Key areas of research include dark matter, dark energy, the cosmic microwave background, large-scale structure, neutrino astronomy and axion astrophysics. A large portion of the department’s research involves numerical cosmological simulations of galaxy formation, large-scale structures and gravitational lensing. The department is developing machine-learning tools to help solve these challenging problems.

    Quantum Theory Department

    Led by Roni Harnik, the Quantum Theory Department has researchers working at the interface of quantum information science and high-energy physics. Fermilab theorists are working to harness the developing power of unique quantum information capabilities to address important physics questions, such as the simulation of QCD processes, dynamics in the early universe, and more generally simulating quantum field theories. Quantum-enhanced capabilities also open new opportunities to explore the universe and test theories of new particles, dark matter, gravitational waves and other new physics.

    Scientists in the Quantum Theory Department are developing new algorithms for quantum simulations, and they are proposing novel methods to search for new phenomena using quantum technology, including quantum optics, atomic physics, optomechanical sensors and superconducting systems. The department works in close collaboration with both the Fermilab Superconducting Quantum Materials and Systems Center and the Fermilab Quantum Institute, as well as leads a national QuantISED theory consortium.

    Looking ahead

    The new Theory Division also intends to play a strong role in attracting and inspiring the next generation of theorists, training them in a data-rich environment, as well as promoting an inclusive culture that values diversity.

    “The best part about being a Fermilab theorist,” said Marcela Carena, “is working with brilliant junior scientists and sharing their excitement about exploring new ideas.”

    See the full article here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Fermi National Accelerator Laboratory (US), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

    Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

    In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest. Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment). The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector. In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.
    In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.
    Asteroid 11998 Fermilab is named in honor of the laboratory.
    Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

    The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.
    After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.
    The later directors include:

    John Peoples, 1989 to 1996
    Michael S. Witherell, July 1999 to June 2005
    Piermaria Oddone, July 2005 to July 2013
    Nigel Lockyer, September 2013 to the present

    Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.

    DOE’s Fermi National Accelerator Laboratory(US)/MINERvA Reidar Hahn.

    FNAL Don Lincoln.[/caption]

    FNAL Icon

     
  • richardmitnick 8:32 am on October 2, 2021 Permalink | Reply
    Tags: "Fermilab on the trail for a new building block of matter and quantum computing power", , , Medill Reports – Northwestern University Chicago (US), Researchers at Fermilab are also working to develop technology for quantum computers that can solve such complex problems exponentially faster than standard computers., Theoretical Physics   

    From Medill Reports – Northwestern University Chicago (US) : “Fermilab on the trail for a new building block of matter and quantum computing power” 

    From Medill Reports – Northwestern University Chicago (US)

    September 30, 2021
    Sarah Anderson and Yuliya Klochan

    Researchers transported a gigantic electromagnetic ring from Brookhaven National Laboratory on Long Island to Fermilab near Chicago eight years ago in the search for a new building block of matter.

    While it wasn’t the secret spaceship bystanders thought it was, it did allow scientists to explore fundamental questions about our universe.

    The ring was needed to confirm an experimental result that had intrigued particle physicists for 20 years. The subject of the experiment was the muon, one of the 17 fundamental particles of nature.

    The muon has the same negative charge as an electron, but the mass of about 200 electrons. Muons behave like tiny spinning tops that generate their own magnetic field.

    In 2001, scientists at DOE’s Brookhaven National Laboratory (US) measured the frequency at which muons rotated in an external magnetic field. This rotation frequency is used to calculate a g factor—a scaling constant that relates the magnetic strength and rotational momentum of the muon. The g factor is important because it can indicate the presence of other particles that block the muons’ interaction with the applied magnetic force.

    The researchers observed that the experimental rotation frequency produced a g factor greater than the value predicted by the standard theoretical model of physics. The Standard Model accounts for all the known fundamental particles and forces of nature, so the Brookhaven result hinted at the existence of undiscovered particles or forces.

    “If these two numbers don’t agree with each other, it’s the space in the middle where the new physics can lie,” said Chris Polly, a senior scientist for the muon experiment at Fermilab.

    3
    The results of the Fermilab and Brookhaven muon experiments do not match the Standard Model prediction, hinting at the existence of an undiscovered particle or force. Credit: Ryan Postel/FERMILAB.

    Fermilab combined its muon-generating particle accelerator with Brookhaven’s electromagnetic ring to repeat Brookhaven’s initial experiment on a much larger scale. They again observed that the measured rotation frequency did not align with the theoretical g factor, suggesting that the Standard Model may need to be overhauled.

    There is only a 1 in 40,000 probability that the results differed by chance, providing further evidence of new physical forces or particles in the universe.

    “Maybe there’s monsters lurking out there that we haven’t even imagined yet,” Polly said.

    As experimental physicists at Fermilab work to replicate this result, theoretical physicists across the world are using simulations to scrutinize their theoretical models. And they need powerful computers to do so.

    Although it’s not yet ready to be used for the muon experiment, researchers at Fermilab are also working to develop technology for quantum computers that can solve such complex problems exponentially faster than standard computers.

    Think of it this way. If someone gave you a list of locations and told you they had stashed a pile of cash at one of them, you would have no choice but to search one location, and then the next, and so on until you found it. Standard computers are subject to this same limitation. Just as you can only be in one place at a time, the system can only occupy one of two defined states (represented by the ones and zeroes you see in computer hacking movies) at a given moment.

    4
    Fermilab’s Quantum Lab features an environmental apparatus for testing superconducting qubits. Credit: Reidar Hahn/FERMILAB.

    But what if you could search many locations at the same time? That’s essentially what a quantum computer does. Its system can occupy multiple superimposed quantum states simultaneously, allowing the computer to consider many possible solutions to a problem at once.

    “It actually is extraordinarily valuable in terms of being able to traverse through the entire computation space much more rapidly than a traditional computer,” said Akshay Murthy, a postdoctoral research associate at Fermilab.

    Murthy and his colleagues are researching computer technology called superconducting qubits (quantum bits) that use electromagnetic radiation to access the higher-energy quantum states. Specifically, they are working to prolong the qubits’ coherence time—the amount of time that the system can live in the quantum space and perform calculations. Right now, we’re getting poofed out of the “everywhere at once” mode before we can find the cash. In fact, the coherence times of qubits need to be 1,000 to 1 million times longer before they can be used for quantum computing.

    To extend coherence times, the team is examining the qubits under a powerful microscope and analyzing the chemical composition of their surfaces to look for any defects that might cause occupation of the quantum states to come crashing down prematurely. They are also exploring modifications that could be made to the external environment, such as shielding the qubit in a freezing cold chamber to prevent temperature fluctuations that might destabilize the system.

    “This technology is truly transformational if we’re able to deliver on its promises,” Murthy said.

    See the full article here.

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Medill Reports-Northwestern University (US) features journalism by students in the graduate program at Northwestern University’s Medill School of Journalism. The students are reporters for Medill News Service. Medill faculty members edit the student work.

     
  • richardmitnick 4:06 pm on August 12, 2021 Permalink | Reply
    Tags: , , , Dark photons-if they exist-are thought to be force-carrying particles., , New: optomechanical membrane accelerometers, , , Theoretical Physics   

    From Symmetry: “Drumming up dark photons” 

    Symmetry Mag

    From Symmetry

    08/03/21
    Mara Johnson-Groh

    1
    Illustration by Sandbox Studio, Chicago with Steve Shanabruch.

    A group of scientists is hoping to detect Dark Matter using a nano-scale drum.

    In the cryogenic-cooled silence of an empty lab, a group of cosmologists, engineers and theoretical physicists hope to someday hear drumbeats.

    The group is searching for a type of theoretical particles called dark photons. And they’re doing it by listening for the particles to tap out a rhythm on a tiny glass drum.

    Dark photons-if they exist-are thought to be force-carrying particles, similar to the regular photons we interact with every day, which carry the electromagnetic force. But unlike massless photons, these dark-matter particles would have a mass, albeit a very small one.

    If they exist in the quantities needed to account for all the dark-matter mass in the universe, dark photons would be so ubiquitous that they would move together like a wave. Individually, dark photons hardly interact with normal matter, but as waves, they would exert a very weak force, theoretical physicists predict.

    The effect would be noticeable only on the smallest scales, but a growing class of nano-instruments specialize in detecting such ultra-small forces on the cusp of quantum limits. Known as optomechanical membrane accelerometers, these devices have previously been used to detect quantum back-action, a weak force important in taking quantum-limited measurements.

    Now, scientists hope to use them to detect the beat of a dark photon wave.

    Drums for dark matter

    Dark matter searches aren’t for pessimists. Despite more than 30 years with no direct detections, physicists are still coming up with new ideas—for both experiments and dark matter candidates. Today, the list of particles is full of superhero and supervillain names like MACHOs, axions, WIMPs, gravitinos and neutralinos. Some models invoke supersymmetry, others superfluids.

    “Right now, the field is in a position where we should leave no rock unturned, because we’ve been looking for years and we haven’t found anything,” says Dalziel Wilson, an assistant professor at the University of Arizona (US) and experimentalist involved with the new search. “So that’s what we’re doing.”

    The idea for using optomechanical devices to detect dark matter was initially made by Swati Singh, an assistant professor at the University of Delaware (US) who currently researches using quantum systems as sensors to search for new physics. After reading proposals to repurpose gravitational-wave detectors to look for dark matter, Singh drew the connection to her previous work with gravitational-wave-sensing mechanical systems.

    “A lot of things we don’t know about—things beyond the Standard Model of particle physics—have signals that are sometimes a very weak force,” Singh says. “As we control more and more devices down to single quanta of motion, we can probe these things and the rest of the universe.”

    To bring her idea to life, Singh formed a multidisciplinary collaboration. Along with her graduate student, Jack Manley, Singh approached Wilson, who has worked with optomechanical resonators for over a decade, and cosmologist Daniel Grin, who specializes in dark-matter candidates.

    Initially, the group wanted to use mechanical detectors to target another type of dark matter, called scalar dark matter. They then realized that dark photons would also affect mechanical detectors, albeit in a different manner.

    A dark photon interacting with a normal atom should slightly alter the position of the atom’s center of mass. So if a wave of dark photons passed, an atom would subtly oscillate back and forth. This effect, though small, could be amplified to the detectable range with optomechanical devices.

    Unlike most dark-matter searches, these detectors are relatively inexpensive and fit on a tabletop. “It turns out, the devices I have in my lab are perfectly capable of searching for this type of dark matter,” Wilson says.

    The group is searching for a type of theoretical particles called dark photons. And they’re doing it by listening for the particles to tap out a rhythm on a tiny glass drum.

    The materials used for the drum were specifically chosen, as dark-photon interactions depend on the density of neutrons in the drum’s atoms. For their first prototype, the group proposed a detector with a membrane made of silicon nitride, less than a micrometer thick, and stretched over a mirror made of beryllium.

    Immersed in a vacuum and cooled down to just 0.01 Kelvin, this type of detector would detect almost no vibration other than that coming from the very tiny dark-photon force, making for a clean signal.

    The detector they designed looks like a drum, but alternative shapes, such as cylinders, cantilevers or balls could work in a similar manner. “In our laboratory, we already have some devices which we think might be more promising,” Wilson says.

    To resonate with dark matter, an optomechanical drum would need to be tuned to the frequency that corresponds to the mass of the dark photon. The trouble is, no one knows exactly what that mass should be.

    “It’s a needle in a haystack. It’s a really, really tiny needle,” says Mitul Dey Chowdhury, a graduate student in Wilson’s lab.

    For now, the group is working to build two detectors. In the coming year or two, they hope to lock their devices away in a quiet room for monthlong runs, during which they will continually listen for the beat of the drum.

    The proposed detector is designed to scan dark-photon frequencies across a large range: from 1 to 100 kilohertz. But it can monitor only a small fraction of that—1/10,000th—at a time.

    Wilson says he hopes their work will inspire other researchers to find optomechanical devices that could be suitable for searching for dark matter. The group has published two peer-reviewed papers, led by Manley, that they hope will interest other groups to join the search. Ideally, a fleet of experiments worldwide, each tuned to a different frequency, would work together to search for dark photons.

    “Right now [this field] is the Wild West,” Wilson says. “I would say maybe in three years we will have some initial results, but it’s very much in its infancy right now.”

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 9:50 am on June 18, 2021 Permalink | Reply
    Tags: "Brookhaven Lab Intern Returns to Continue Theoretical Physics Pursuit", Co-design Center for Quantum Advantage (C2QA), DOE Science Undergraduate Laboratory Internships, National Quantum Information Science Research Centers, , , , , Theoretical Physics, Wenjie Gong recently received a Barry Goldwater Scholarship., Women in STEM-Wenjie Gong   

    From DOE’s Brookhaven National Laboratory (US) : Women in STEM-Wenjie Gong “Brookhaven Lab Intern Returns to Continue Theoretical Physics Pursuit” 

    From DOE’s Brookhaven National Laboratory (US)

    June 14, 2021
    Kelly Zegers
    kzegewrs@bnl.gov

    Wenjie Gong virtually visits Brookhaven for an internship to perform theory research on quantum information science in nuclear physics.

    1
    Wenjie Gong, who recently received a Barry Goldwater Scholarship. (Courtesy photo.)

    Internships often help students nail down the direction they’d like to take their scientific pursuits. For Wenjie Gong, who just completed her junior year at Harvard University (US), a first look into theoretical physics last summer as an intern with the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory made her want to dive further into the field.

    Gong returns to Brookhaven Lab this summer for her second experience as a virtual DOE Science Undergraduate Laboratory Internships (SULI) participant to continue collaborating with Raju Venugopalan, a senior physicist and Nuclear Theory Group leader. Together, they will explore the connections between nuclear physics theory—which explores the interactions of fundamental particles—and quantum computing.

    “I find theoretical physics fascinating as there are so many different avenues to explore and so many different angles from which to approach a problem,” Gong said. “Even though it can be difficult to parse through the technical underpinnings of different physical situations, any progress made is all the more exciting and rewarding.”

    Last year, Gong collaborated with Venugopalan on a project exploring possible ways to measure a quantum phenomenon known as “entanglement” in the matter produced at high-energy collisions.

    The physical properties of entangled particles are inextricably linked, even when the particles are separated by a great distance. Albert Einstein referred to entanglement as “spooky action at distance.”

    Studying this phenomenon is an important part of setting up long-distance quantum computing networks—the topic of many of the experiments at Co-design Center for Quantum Advantage (C2QA). The center led by Brookhaven Lab is one of five National Quantum Information Science Research Centers and applies quantum principles to materials, devices and software co-design efforts to lay the foundation for a new generation of quantum computers.

    “Usually, entanglement requires very precise measurements that are found in optics laboratories, but we wanted to look at how we could understand entanglement in high-energy particle collisions, which have much less of a controlled environment,” Gong said.

    Venugopalan said the motivation behind thinking of ways to detect entanglement in high-energy collisions is two-fold, first asking the question: “Can we think of experimental measures in collider experiments that have comparable ability to extract quantum action-at-a distance just as the carefully designed tabletop experiments?”

    “That would be interesting in itself because one might be inclined to think it unlikely,” he said.

    Venugopalan said scientists have identified sub-atomic particle correlations of so-called Lambda hyperons, which have particular properties that may allow such an experiment. Those experiments would open up the question of whether entanglement persists if scientists change the conditions of the collisions, he said.

    “If we made the collisions more violent, say, by increasing the number of particles produced, would the quantum action-at-a-distance correlation go away, just as you, and I, as macroscopic quantum states, don’t exhibit any spooky action-at-a-distance nonsense,” Venugopalan said. “When does such a quantum-to-classical transition take place?”

    In addition, can such measurements teach us about the nature of the interactions of the building blocks of matter–quarks and gluons?

    There may be more questions than answers at this stage, “but these questions force us to refine our experimental and computational tools,” Venugopalan said.

    Gong will continue collaborating with Venugopalan to develop the project on entanglement this summer. She may also start a new project exploring quirky features of soft particles in the quantum theory of electromagnetism that also apply to the strong force of nuclear physics, Venugopalan said. While her internship is virtual again this year, she said she learned last summer that collaborating remotely can be productive and rewarding.

    “Wenjie is the real deal,” Venugopalan said. “Even as a rising junior, she was functioning at the level of a postdoc. It’s a great joy to exchange ‘crazy’ ideas with her and work out the consequences. She shows great promise for an outstanding career in theoretical physics.”

    Others have noticed Gong’s scientific talent. She was recently honored with a Barry M. Goldwater Scholarship. The prestigious award supports impressive undergraduates who plan to pursue a PhD in the natural sciences, mathematics, and engineering.

    “I feel really honored and also very grateful to Raju, the Department of Energy (US) , and Brookhaven for providing me the opportunity to do this research—which I wrote about in my Goldwater essay,” Gong said.

    Gong said she’s looking forward to applying concepts from courses she took at Harvard over the past year, including quantum field theory, which she found challenging but also rewarding.

    Gong’s interest in physics started when she took Advanced Placement (AP) Physics in high school. The topic drew her in because it requires a way of thinking that’s different compared to other sciences because it explores the laws governing the motion of matter and existence, she said.

    In addition to further exploring high energy theoretical physics research, Gong said she hopes to one day teach as a university professor. She’s currently a peer tutor at Harvard.

    “I love teaching physics,” she said. “It’s really cool to see the ‘Ah-ha!’ moment when students go from not really understanding something to grasping a concept.”

    The SULI program at Brookhaven is managed by the Lab’s Office of Educational Programs and sponsored by DOE’s Office of Workforce Development for Teachers and Scientists (WDTS) within the Department’s Office of Science.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

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

    Research at BNL specializes in nuclear and high energy physics, energy science and technology, environmental and bioscience, nanoscience and national security. The 5,300 acre campus contains several large research facilities, including the Relativistic Heavy Ion Collider [below] and National Synchrotron Light Source II [below]. Seven Nobel prizes have been awarded for work conducted at Brookhaven lab.

    BNL is staffed by approximately 2,750 scientists, engineers, technicians, and support personnel, and hosts 4,000 guest investigators every year. The laboratory has its own police station, fire department, and ZIP code (11973). In total, the lab spans a 5,265-acre (21 km^2) area that is mostly coterminous with the hamlet of Upton, New York. BNL is served by a rail spur operated as-needed by the New York and Atlantic Railway. Co-located with the laboratory is the Upton, New York, forecast office of the National Weather Service.

    Major programs

    Although originally conceived as a nuclear research facility, Brookhaven Lab’s mission has greatly expanded. Its foci are now:

    Nuclear and high-energy physics
    Physics and chemistry of materials
    Environmental and climate research
    Nanomaterials
    Energy research
    Nonproliferation
    Structural biology
    Accelerator physics

    Operation

    Brookhaven National Lab was originally owned by the Atomic Energy Commission(US) and is now owned by that agency’s successor, the United States Department of Energy (DOE). DOE subcontracts the research and operation to universities and research organizations. It is currently operated by Brookhaven Science Associates LLC, which is an equal partnership of Stony Brook University(US) and Battelle Memorial Institute(US). From 1947 to 1998, it was operated by Associated Universities, Inc. (AUI) (US), but AUI lost its contract in the wake of two incidents: a 1994 fire at the facility’s high-beam flux reactor that exposed several workers to radiation and reports in 1997 of a tritium leak into the groundwater of the Long Island Central Pine Barrens on which the facility sits.

    Foundations

    Following World War II, the US Atomic Energy Commission was created to support government-sponsored peacetime research on atomic energy. The effort to build a nuclear reactor in the American northeast was fostered largely by physicists Isidor Isaac Rabi and Norman Foster Ramsey Jr., who during the war witnessed many of their colleagues at Columbia University leave for new remote research sites following the departure of the Manhattan Project from its campus. Their effort to house this reactor near New York City was rivalled by a similar effort at the Massachusetts Institute of Technology (US) to have a facility near Boston, Massachusettes(US). Involvement was quickly solicited from representatives of northeastern universities to the south and west of New York City such that this city would be at their geographic center. In March 1946 a nonprofit corporation was established that consisted of representatives from nine major research universities — Columbia University(US), Cornell University(US), Harvard University(US), Johns Hopkins University(US), Massachusetts Institute of Technology(US), Princeton University(US), University of Pennsylvania(US), University of Rochester(US), and Yale University(US).

    Out of 17 considered sites in the Boston-Washington corridor, Camp Upton on Long Island was eventually chosen as the most suitable in consideration of space, transportation, and availability. The camp had been a training center from the US Army during both World War I and World War II. After the latter war, Camp Upton was deemed no longer necessary and became available for reuse. A plan was conceived to convert the military camp into a research facility.

    On March 21, 1947, the Camp Upton site was officially transferred from the U.S. War Department to the new U.S. Atomic Energy Commission (AEC), predecessor to the U.S. Department of Energy (DOE).

    Research and facilities

    Reactor history

    In 1947 construction began on the first nuclear reactor at Brookhaven, the Brookhaven Graphite Research Reactor. This reactor, which opened in 1950, was the first reactor to be constructed in the United States after World War II. The High Flux Beam Reactor operated from 1965 to 1999. In 1959 Brookhaven built the first US reactor specifically tailored to medical research, the Brookhaven Medical Research Reactor, which operated until 2000.

    Accelerator history

    In 1952 Brookhaven began using its first particle accelerator, the Cosmotron. At the time the Cosmotron was the world’s highest energy accelerator, being the first to impart more than 1 GeV of energy to a particle.


    The Cosmotron was retired in 1966, after it was superseded in 1960 by the new Alternating Gradient Synchrotron (AGS).

    The AGS was used in research that resulted in 3 Nobel prizes, including the discovery of the muon neutrino, the charm quark, and CP violation.

    In 1970 in BNL started the ISABELLE project to develop and build two proton intersecting storage rings.

    The groundbreaking for the project was in October 1978. In 1981, with the tunnel for the accelerator already excavated, problems with the superconducting magnets needed for the ISABELLE accelerator brought the project to a halt, and the project was eventually cancelled in 1983.

    The National Synchrotron Light Source (US) operated from 1982 to 2014 and was involved with two Nobel Prize-winning discoveries. It has since been replaced by the National Synchrotron Light Source II (US) [below].

    After ISABELLE’S cancellation, physicist at BNL proposed that the excavated tunnel and parts of the magnet assembly be used in another accelerator. In 1984 the first proposal for the accelerator now known as the Relativistic Heavy Ion Collider (RHIC)[below] was put forward. The construction got funded in 1991 and RHIC has been operational since 2000. One of the world’s only two operating heavy-ion colliders, RHIC is as of 2010 the second-highest-energy collider after the Large Hadron Collider(CH). RHIC is housed in a tunnel 2.4 miles (3.9 km) long and is visible from space.

    On January 9, 2020, It was announced by Paul Dabbar, undersecretary of the US Department of Energy Office of Science, that the BNL eRHIC design has been selected over the conceptual design put forward by DOE’s Thomas Jefferson National Accelerator Facility [Jlab] (US) as the future Electron–ion collider (EIC) in the United States.

    In addition to the site selection, it was announced that the BNL EIC had acquired CD-0 (mission need) from the Department of Energy. BNL’s eRHIC design proposes upgrading the existing Relativistic Heavy Ion Collider, which collides beams light to heavy ions including polarized protons, with a polarized electron facility, to be housed in the same tunnel.

    Other discoveries

    In 1958, Brookhaven scientists created one of the world’s first video games, Tennis for Two. In 1968 Brookhaven scientists patented Maglev, a transportation technology that utilizes magnetic levitation.

    Major facilities

    Relativistic Heavy Ion Collider (RHIC), which was designed to research quark–gluon plasma and the sources of proton spin. Until 2009 it was the world’s most powerful heavy ion collider. It is the only collider of spin-polarized protons.
    Center for Functional Nanomaterials (CFN), used for the study of nanoscale materials.
    BNL National Synchrotron Light Source II(US), Brookhaven’s newest user facility, opened in 2015 to replace the National Synchrotron Light Source (NSLS), which had operated for 30 years.[19] NSLS was involved in the work that won the 2003 and 2009 Nobel Prize in Chemistry.
    Alternating Gradient Synchrotron, a particle accelerator that was used in three of the lab’s Nobel prizes.
    Accelerator Test Facility, generates, accelerates and monitors particle beams.
    Tandem Van de Graaff, once the world’s largest electrostatic accelerator.
    Computational Science resources, including access to a massively parallel Blue Gene series supercomputer that is among the fastest in the world for scientific research, run jointly by Brookhaven National Laboratory and Stony Brook University.
    Interdisciplinary Science Building, with unique laboratories for studying high-temperature superconductors and other materials important for addressing energy challenges.
    NASA Space Radiation Laboratory, where scientists use beams of ions to simulate cosmic rays and assess the risks of space radiation to human space travelers and equipment.

    Off-site contributions

    It is a contributing partner to ATLAS experiment, one of the four detectors located at the Large Hadron Collider (LHC).


    It is currently operating at CERN near Geneva, Switzerland.

    Brookhaven was also responsible for the design of the SNS accumulator ring in partnership with Spallation Neutron Source at DOE’s Oak Ridge National Laboratory (US), Tennessee.

    Brookhaven plays a role in a range of neutrino research projects around the world, including the Daya Bay Neutrino Experiment (CN) nuclear power plant, approximately 52 kilometers northeast of Hong Kong and 45 kilometers east of Shenzhen, China.


     
  • richardmitnick 4:12 pm on June 2, 2021 Permalink | Reply
    Tags: , , Extending the idea of dark matter ‘talking’ to dark forces., , If two particles of dark matter are attracted to or repelled by each other then dark forces are operating., It is proposed that there may be a fourth dimension that only the dark forces know about., , , , The key feature of the extra-dimensional theory is that the force between dark matter particles is described by an infinite number of different particles with different masses called a continuum., The new research proposes the existence of an extra dimension in space-time., The team will explore a continuum version of the “dark photon” model., Theoretical Physics,   

    From UC Riverside (US) : “A new dimension in the quest to understand dark matter” 

    UC Riverside bloc

    From UC Riverside (US)

    1
    Flip Tanedo.

    As its name suggests, Dark Matter — material which makes up about 85% of the mass in the universe — emits no light, eluding easy detection. Its properties, too, remain fairly obscure.

    _____________________________________________________________________________________

    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.


    _____________________________________________________________________________________

    Now, a theoretical particle physicist at the University of California, Riverside, and colleagues have published a research paper in the Journal of High Energy Physics that shows how theories positing the existence a new type of force could help explain dark matter’s properties.

    2
    Photo shows Flip Tanedo (left), Sylvain Fichet (center), and Hai-Bo Yu. Credit: Flip Tanedo/UCR.

    “We live in an ocean of dark matter, yet we know very little about what it could be,” said Flip Tanedo, an assistant professor of physics and astronomy and the paper’s senior author. “It is one of the most vexing known unknowns in nature. We know it exists, but we do not know how to look for it or why it hasn’t shown up where we expected it.”

    Physicists have used telescopes, gigantic underground experiments, and colliders to learn more about dark matter for the last 30 years, though no positive evidence has materialized. The negative evidence, however, has forced theoretical physicists like Tanedo to think more creatively about what dark matter could be.

    The new research, which proposes the existence of an extra dimension in space-time to search for dark matter, is part of an ongoing research program at UC Riverside led by Tanedo. According to this theory, some of the dark matter particles don’t behave like particles. In effect, invisible particles interact with even more invisible particles in such a way that the latter cease to behave like particles.

    “The goal of my research program for the past two years is to extend the idea of dark matter ‘talking’ to dark forces,” Tanedo said. “Over the past decade, physicists have come to appreciate that, in addition to dark matter, hidden dark forces may govern dark matter’s interactions. These could completely rewrite the rules for how one ought to look for dark matter.”

    If two particles of dark matter are attracted to or repelled by each other then dark forces are operating. Tanedo explained that dark forces are described mathematically by a theory with extra dimensions and appear as a continuum of particles that could address puzzles seen in small galaxies.

    “Our ongoing research program at UCR is a further generalization of the dark force proposal,” he said. “Our observed universe has three dimensions of space. We propose that there may be a fourth dimension that only the dark forces know about. The extra dimension can explain why dark matter has hidden so well from our attempts to study it in a lab.”

    Tanedo explained that although extra dimensions may sound like an exotic idea, they are actually a mathematical trick to describe “conformal field theories” — ordinary three-dimensional theories that are highly quantum mechanical. These types of theories are mathematically rich, but do not contain conventional particles and so are typically not considered to be relevant for describing nature. The mathematical equivalence between these challenging three-dimensional theories and a more tractable extra dimensional theory is known as the holographic principle.

    “Since these conformal field theories were both intractable and unusual, they hadn’t really been systematically applied to dark matter,” Tanedo added. “Instead of using that language, we work with the holographic extra-dimensional theory.”

    The key feature of the extra-dimensional theory is that the force between dark matter particles is described by an infinite number of different particles with different masses called a continuum. In contrast, ordinary forces are described by a single type of particle with a fixed mass. This class of continuum-dark sectors is exciting to Tanedo because it does something “fresh and different.”

    According to Tanedo, past work on dark sectors focuses primarily on theories that mimic the behavior of visible particles. His research program is exploring the more extreme types of theories that most particle physicists found less interesting, perhaps because no analogs exist in the real world.

    In Tanedo’s theory, the force between dark matter particles is surprisingly different from the forces felt by ordinary matter.

    “For the gravitational force or electric force that I teach in my introductory physics course, when you double the distance between two particles you reduce the force by a factor of four. A continuum force, on the other hand, is reduced by a factor of up to eight.”

    What implications does this extra dimensional dark force have? Since ordinary matter may not interact with this dark force, Tanedo turned to the idea of self-interacting dark matter, an idea pioneered by Hai-Bo Yu, an associate professor of physics and astronomy at UCR who is not a coauthor on the paper. Yu showed that even in the absence of any interactions with normal matter, the effects of these dark forces could be observed indirectly in dwarf spheroidal galaxies. Tanedo’s team found the continuum force can reproduce the observed stellar motions.

    “Our model goes further and makes it easier than the self-interacting dark matter model to explain the cosmic origin of dark matter,” Tanedo said.

    Next, Tanedo’s team will explore a continuum version of the “dark photon” model.

    “It’s a more realistic picture for a dark force,” Tanedo said. “Dark photons have been studied in great detail, but our extra-dimensional framework has a few surprises. We will also look into the cosmology of dark forces and the physics of black holes.”

    Tanedo has been working diligently on identifying “blind spots” in his team’s search for dark matter.

    “My research program targets one of the assumptions we make about particle physics: that the interaction of particles is well-described by the exchange of more particles,” he said. “While that is true for ordinary matter, there’s no reason to assume that for dark matter. Their interactions could be described by a continuum of exchanged particles rather than just exchanging a single type of force particle.”

    Tanedo was joined in the research by Ian Chaffey, a postdoctoral researcher working with Tanedo; and Sylvain Fichet, a postdoctoral researcher at the International Center for Theoretical Physics – South American Institute for Fundamental Research in Brazil.

    The research was funded by the U.S. Department of Energy.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC Riverside Campus

    The University of California, Riverside (US) is a public land-grant research university in Riverside, California. It is one of the 10 campuses of the University of California (US) system. The main campus sits on 1,900 acres (769 ha) in a suburban district of Riverside with a branch campus of 20 acres (8 ha) in Palm Desert. In 1907, the predecessor to UC Riverside was founded as the UC Citrus Experiment Station, Riverside which pioneered research in biological pest control and the use of growth regulators responsible for extending the citrus growing season in California from four to nine months. Some of the world’s most important research collections on citrus diversity and entomology, as well as science fiction and photography, are located at Riverside.

    UC Riverside’s undergraduate College of Letters and Science opened in 1954. The Regents of the University of California declared UC Riverside a general campus of the system in 1959, and graduate students were admitted in 1961. To accommodate an enrollment of 21,000 students by 2015, more than $730 million has been invested in new construction projects since 1999. Preliminary accreditation of the UC Riverside School of Medicine was granted in October 2012 and the first class of 50 students was enrolled in August 2013. It is the first new research-based public medical school in 40 years.

    UC Riverside is classified among “R1: Doctoral Universities – Very high research activity.” The 2019 U.S. News & World Report Best Colleges rankings places UC Riverside tied for 35th among top public universities and ranks 85th nationwide. Over 27 of UC Riverside’s academic programs, including the Graduate School of Education and the Bourns College of Engineering, are highly ranked nationally based on peer assessment, student selectivity, financial resources, and other factors. Washington Monthly ranked UC Riverside 2nd in the United States in terms of social mobility, research and community service, while U.S. News ranks UC Riverside as the fifth most ethnically diverse and, by the number of undergraduates receiving Pell Grants (42 percent), the 15th most economically diverse student body in the nation. Over 70% of all UC Riverside students graduate within six years without regard to economic disparity. UC Riverside’s extensive outreach and retention programs have contributed to its reputation as a “university of choice” for minority students. In 2005, UCR became the first public university campus in the nation to offer a gender-neutral housing option.UC Riverside’s sports teams are known as the Highlanders and play in the Big West Conference of the National Collegiate Athletic Association (NCAA) Division I. Their nickname was inspired by the high altitude of the campus, which lies on the foothills of Box Springs Mountain. The UC Riverside women’s basketball team won back-to-back Big West championships in 2006 and 2007. In 2007, the men’s baseball team won its first conference championship and advanced to the regionals for the second time since the university moved to Division I in 2001.

    History

    At the turn of the 20th century, Southern California was a major producer of citrus, the region’s primary agricultural export. The industry developed from the country’s first navel orange trees, planted in Riverside in 1873. Lobbied by the citrus industry, the UC Regents established the UC Citrus Experiment Station (CES) on February 14, 1907, on 23 acres (9 ha) of land on the east slope of Mount Rubidoux in Riverside. The station conducted experiments in fertilization, irrigation and crop improvement. In 1917, the station was moved to a larger site, 475 acres (192 ha) near Box Springs Mountain.

    The 1944 passage of the GI Bill during World War II set in motion a rise in college enrollments that necessitated an expansion of the state university system in California. A local group of citrus growers and civic leaders, including many UC Berkeley(US) alumni, lobbied aggressively for a UC-administered liberal arts college next to the CES. State Senator Nelson S. Dilworth authored Senate Bill 512 (1949) which former Assemblyman Philip L. Boyd and Assemblyman John Babbage (both of Riverside) were instrumental in shepherding through the State Legislature. Governor Earl Warren signed the bill in 1949, allocating $2 million for initial campus construction.

    Gordon S. Watkins, dean of the College of Letters and Science at University of California at Los Angeles(US), became the first provost of the new college at Riverside. Initially conceived of as a small college devoted to the liberal arts, he ordered the campus built for a maximum of 1,500 students and recruited many young junior faculty to fill teaching positions. He presided at its opening with 65 faculty and 127 students on February 14, 1954, remarking, “Never have so few been taught by so many.”

    UC Riverside’s enrollment exceeded 1,000 students by the time Clark Kerr became president of the University of California(US) system in 1958. Anticipating a “tidal wave” in enrollment growth required by the baby boom generation, Kerr developed the California Master Plan for Higher Education and the Regents designated Riverside a general university campus in 1959. UC Riverside’s first chancellor, Herman Theodore Spieth, oversaw the beginnings of the school’s transition to a full university and its expansion to a capacity of 5,000 students. UC Riverside’s second chancellor, Ivan Hinderaker led the campus through the era of the free speech movement and kept student protests peaceful in Riverside. According to a 1998 interview with Hinderaker, the city of Riverside received negative press coverage for smog after the mayor asked Governor Ronald Reagan to declare the South Coast Air Basin a disaster area in 1971; subsequent student enrollment declined by up to 25% through 1979. Hinderaker’s development of innovative programs in business administration and biomedical sciences created incentive for enough students to enroll at Riverside to keep the campus open.

    In the 1990s, the UC Riverside experienced a new surge of enrollment applications, now known as “Tidal Wave II”. The Regents targeted UC Riverside for an annual growth rate of 6.3%, the fastest in the UC system, and anticipated 19,900 students at UC Riverside by 2010. By 1995, African American, American Indian, and Latino student enrollments accounted for 30% of the UC Riverside student body, the highest proportion of any UC campus at the time. The 1997 implementation of Proposition 209—which banned the use of affirmative action by state agencies—reduced the ethnic diversity at the more selective UC campuses but further increased it at UC Riverside.

    With UC Riverside scheduled for dramatic population growth, efforts have been made to increase its popular and academic recognition. The students voted for a fee increase to move UC Riverside athletics into NCAA Division I standing in 1998. In the 1990s, proposals were made to establish a law school, a medical school, and a school of public policy at UC Riverside, with the UC Riverside School of Medicine and the School of Public Policy becoming reality in 2012. In June 2006, UC Riverside received its largest gift, 15.5 million from two local couples, in trust towards building its medical school. The Regents formally approved UC Riverside’s medical school proposal in 2006. Upon its completion in 2013, it was the first new medical school built in California in 40 years.

    Academics

    As a campus of the University of California(US) system, UC Riverside is governed by a Board of Regents and administered by a president. The current president is Michael V. Drake, and the current chancellor of the university is Kim A. Wilcox. UC Riverside’s academic policies are set by its Academic Senate, a legislative body composed of all UC Riverside faculty members.

    UC Riverside is organized into three academic colleges, two professional schools, and two graduate schools. UC Riverside’s liberal arts college, the College of Humanities, Arts and Social Sciences, was founded in 1954, and began accepting graduate students in 1960. The College of Natural and Agricultural Sciences, founded in 1960, incorporated the CES as part of the first research-oriented institution at UC Riverside; it eventually also incorporated the natural science departments formerly associated with the liberal arts college to form its present structure in 1974. UC Riverside’s newest academic unit, the Bourns College of Engineering, was founded in 1989. Comprising the professional schools are the Graduate School of Education, founded in 1968, and the UCR School of Business, founded in 1970. These units collectively provide 81 majors and 52 minors, 48 master’s degree programs, and 42 Doctor of Philosophy (PhD) programs. UC Riverside is the only UC campus to offer undergraduate degrees in creative writing and public policy and one of three UCs (along with University of California-Berkeley (US) and University of California-Irvine (US)) to offer an undergraduate degree in business administration. Through its Division of Biomedical Sciences, founded in 1974, UC Riverside offers the Thomas Haider medical degree program in collaboration with University of California-Los Angeles(US). UC Riverside’s doctoral program in the emerging field of dance theory, founded in 1992, was the first program of its kind in the United States, and UC Riverside’s minor in lesbian, gay and bisexual studies, established in 1996, was the first undergraduate program of its kind in the UC system. A new BA program in bagpipes was inaugurated in 2007.

    Research and economic impact

    UC Riverside operated under a $727 million budget in fiscal year 2014–15. The state government provided $214 million, student fees accounted for $224 million and $100 million came from contracts and grants. Private support and other sources accounted for the remaining $189 million. Overall, monies spent at UC Riverside have an economic impact of nearly $1 billion in California. UC Riverside research expenditure in FY 2018 totaled $167.8 million. Total research expenditures at UC Riverside are significantly concentrated in agricultural science, accounting for 53% of total research expenditures spent by the university in 2002. Top research centers by expenditure, as measured in 2002, include the Agricultural Experiment Station; the Center for Environmental Research and Technology; the Center for Bibliographical Studies; the Air Pollution Research Center; and the Institute of Geophysics and Planetary Physics.

    Throughout UC Riverside’s history, researchers have developed more than 40 new citrus varieties and invented new techniques to help the $960 million-a-year California citrus industry fight pests and diseases. In 1927, entomologists at the CES introduced two wasps from Australia as natural enemies of a major citrus pest, the citrophilus mealybug, saving growers in Orange County $1 million in annual losses. This event was pivotal in establishing biological control as a practical means of reducing pest populations. In 1963, plant physiologist Charles Coggins proved that application of gibberellic acid allows fruit to remain on citrus trees for extended periods. The ultimate result of his work, which continued through the 1980s, was the extension of the citrus-growing season in California from four to nine months. In 1980, UC Riverside released the Oroblanco grapefruit, its first patented citrus variety. Since then, the citrus breeding program has released other varieties such as the Melogold grapefruit, the Gold Nugget mandarin (or tangerine), and others that have yet to be given trademark names.

    To assist entrepreneurs in developing new products, UC Riverside is a primary partner in the Riverside Regional Technology Park, which includes the City of Riverside and the County of Riverside. It also administers six reserves of the University of California Natural Reserve System. UC Riverside recently announced a partnership with China Agricultural University[中国农业大学](CN) to launch a new center in Beijing, which will study ways to respond to the country’s growing environmental issues. UC Riverside can also boast the birthplace of two name reactions in organic chemistry, the Castro-Stephens coupling and the Midland Alpine Borane Reduction.

     
  • richardmitnick 5:14 pm on February 1, 2021 Permalink | Reply
    Tags: "Searching for dark matter through the fifth dimension", , Even the abundance of dark matter in the cosmos as observed in astrophysical experiments can be explained by their theory., , , The 5-dimensional field equations predicted the existence of a new heavy particle with similar properties as the famous Higgs boson but a much heavier mass., The embedding of the Standard Model of particle physics in a 5-dimensional spacetime could explain the so far mysterious patterns seen in the masses of elementary particles., The existence of a fifth dimension could resolve some of the profound open questions of particle physics., The mechanism discovered would make dark matter accessible to forthcoming experiments because the properties of the new interaction between ordinary matter and dark matter., The proposed particle would necessarily mediate a new force between the known elementary particles of our visible universe and the mysterious dark matter-the dark sector., Theoretical Physics   

    From Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Searching for dark matter through the fifth dimension” 

    From Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

    1 February 2021

    Professor Dr. Matthias Neubert
    Theoretical High Energy Physics (THEP)
    Institute of Physics
    Johannes Gutenberg University Mainz
    55099 Mainz (DE)
    neubertm@uni-mainz.de

    A discovery in theoretical physics could help to unravel the mysteries of dark matter.

    1
    Credit: CC0 Public Domain.

    Theoretical physicists of the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) are working on a theory that goes beyond the Standard Model of particle physics and can answer questions where the Standard Model has to pass – for example, with respect to the hierarchies of the masses of elementary particles or the existence of dark matter.

    Standard Model of Particle Physics (LATHAM BOYLE AND MARDUS OF WIKIMEDIA COMMONS).

    The central element of the theory is an extra dimension in spacetime. Until now, scientists have faced the problem that the predictions of their theory could not be tested experimentally. They have now overcome this problem in a publication in the current issue of the European Physical Journal C.

    Already in the 1920s, in an attempt to unify the forces of gravity and electromagnetism, Theodor Kaluza and Oskar Klein speculated about the existence of an extra dimension beyond the familiar three space dimensions and time – which in physics are combined into 4-dimensional spacetime. If it exists, such a new dimension would have to be incredible tiny and unnoticeable to the human eye. In the late 1990s, this idea has seen a remarkable renaissance when it was realized that the existence of a fifth dimension could resolve some of the profound open questions of particle physics. In particular, Yuval Grossman of Stanford University and Matthias Neubert, then a professor at Cornell University in the US, showed in a highly cited publication that the embedding of the Standard Model of particle physics in a 5-dimensional spacetime could explain the so far mysterious patterns seen in the masses of elementary particles.

    Another 20 years later, the group of Professor Matthias Neubert – since 2006 on the faculty of Johannes Gutenberg University Mainz and spokesperson of the PRISMA+ Cluster of Excellence – made another unexpected discovery: they found that the 5-dimensional field equations predicted the existence of a new heavy particle with similar properties as the famous Higgs boson but a much heavier mass – so heavy, in fact, that it cannot be produced even at the highest-energy particle collider in the world, the Large Hadron Collider (LHC) at the European Center for Nuclear Research CERN near Geneva in Switzerland. “It was a nightmare,” recalled Javier Castellano Ruiz, a PhD student involved in the research. “We were excited by the idea that our theory predicts a new particle, but it appeared to be impossible to confirm this prediction in any foreseeable experiment.”

    The detour through the fifth dimension

    In a recent paper published in the European Physical Journal C, the researchers found a spectacular resolution to this dilemma. They discovered that their proposed particle would necessarily mediate a new force between the known elementary particles of our visible universe and the mysterious dark matter, the dark sector. Even the abundance of dark matter in the cosmos, as observed in astrophysical experiments, can be explained by their theory. This offers exciting new ways to search for the constituents of the dark matter – literally via a detour through the extra dimension – and obtain clues about the physics at a very early stage in the history of our universe, when dark matter was produced. “After years of searching for possible confirmations of our theoretical predictions, we are now confident that the mechanism we have discovered would make dark matter accessible to forthcoming experiments, because the properties of the new interaction between ordinary matter and dark matter – which is mediated by our proposed particle – can be calculated accurately within our theory,” said Professor Matthias Neubert, head of the research team. “In the end – so our hope – the new particle may be discovered first through its interactions with the dark sector.” This example nicely illustrates the fruitful interplay between experimental and theoretical basic science – a hallmark of the PRISMA+ Cluster of Excellence.

    See the full article here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

    The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

    The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, the Goethe University Frankfurt and the Technische Universität Darmstadt together form the Rhine-Main-Universities (RMU).

    The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).
    Statue of Johannes Gutenberg at the University of Mainz.

    The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

    The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

    In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

     
  • richardmitnick 11:02 pm on December 9, 2020 Permalink | Reply
    Tags: "Physics professor advances research on black hole paradox", , , It turns out that a powerful way to learn about one black hole is to study two black holes., Late physicist Stephen Hawking showed that when quantum effects are included black holes do have a temperature., Theoretical Physics   

    From Cornell Chronicle: “Physics professor advances research on black hole paradox” 

    From Cornell Chronicle

    December 9, 2020
    Kate Blackwood
    cunews@cornell.edu

    1
    Thomas Hartman, right, associate professor of physics, and Amirhossein Tajdini, Ph.D. ’20, diagram in 2019 a replica wormhole, a concept associated with quantum gravity. They were two authors of “Replica Wormholes and the Entropy of Hawking Radiation,” a paper important to recent progress on the black hole paradox. Credit: Dave Burbank/Cornell University.

    Do black holes emit information?

    For decades, physicists have theorized on this high-stakes question. At the heart of the so-called “black hole information paradox” is a fundamental incompatibility between the two pillar theories of theoretical physics: general relativity and quantum mechanics.

    But in the past two years, a series of breakthrough calculations by researchers – including Tom Hartman, associate professor of physics in the College of Arts and Sciences – have led to proclamations in the field of theoretical physics that “the most famous paradox in physics,” according to Quanta Magazine, is nearing its end.

    “It’s fair to say that these calculations have given us a new way to think about black hole information and given us hints about how to make sense of quantum gravity,” Hartman said, confirming the progress and his significant contribution. “It solves some corner of the paradox.”

    Hartman researches quantum gravity, a theory to reconcile quantum mechanics and general relativity. His paper published in May in the Journal of High Energy Physics, reports a mathematical technique for calculating the physics of a black hole. Collaborators on the paper included former Cornell postdoctoral researcher Edgar Shaghoulian, now a postdoc at the University of Pennsylvania; and Amir Tajdini, Ph.D. ’20, now a postdoc at the University of California, Santa Barbara.

    “Black holes are a place where both quantum mechanics and gravity can be important at the same time,” Hartman said. “If you’re thinking about quantum gravity and how to put the two theories together, black holes are a great way to study that problem.”

    Although we think of black holes as having nothing coming out from them, Hartman said, late physicist Stephen Hawking showed that when quantum effects are included, black holes do have a temperature.

    This leads to the paradox: The fact that black holes have a temperature, Hartman said, means that particles are escaping the black hole. Hawking found that these particles are “pure thermal radiation,” or radiation that is completely random and does not carry any information, Hartman said. If this is true, then when a black hole evaporates away and disappears, the information that was originally contained in the black hole has been destroyed, he said.

    “It is a fundamental principle of quantum mechanics that information cannot be destroyed,” Hartman said. “So the paradox is a contradiction between quantum mechanics and Hawking’s calculation showing that black holes radiate randomly.”

    In the paper, Hartman and collaborators used a mathematical trick involving extra copies of the black hole called “replicas” to calculate the physics of a single black hole.

    “It turns out that a powerful way to learn about one black hole is to study two black holes,” he said. “The reason is that there are statistical properties of radiation that are hard to understand if you look at one black hole but easier to understand if you look at two at once.”

    Using this technique, they found evidence that the particles emitted in Hawking radiation are not random, after all.

    In November, Hartman published further research in the Journal of High Energy Physics. In the paper, he and Shaghoulian, along with Yikun Jiang, a Ph.D. student in the field of physics, explore the possibility that the new theory of Hawking radiation could also apply to the early universe.

    Hartman co-organized a virtual workshop on this and related topics in November with researchers from Stanford and the University of California, San Diego, joined by 40 participants from around the world.

    Far from being near an end, the information paradox is a problem that multiplies as physicists look into it, Hartman said. What started as one paradox has grown into a whole field of study.

    “There are many aspects of it,” he said. “It’s something thousands of people will work on for decades.”

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

     
  • richardmitnick 1:40 pm on November 20, 2020 Permalink | Reply
    Tags: "The gravity of dreams", , , , Lavinia Heisenberg, , Theoretical Physics, Why is gravity the most mysterious force of nature?   

    From ETH Zürich (CH): “The gravity of dreams” Lavinia Heisenberg 

    From ETH Zürich (CH)

    20.11.2020
    Florian Meyer

    Why is gravity the most mysterious force of nature? Lavinia Heisenberg studies how the universe was formed, and how it is changing. She has now been awarded the ETH Zürich Latsis Prize for her outstanding achievements in the field of theoretical physics.


    The gravity of dreams – Portrait Lavinia Heisenberg.

    3
    Lavinia Heisenberg

    Anyone who observes the sky at night may have an idea of what Lavinia Heisenberg does for a living. She is a cosmologist. Her field of research is space and what is to be found there, whether visible or dark matter, light or energy, particles or waves, bodies or forces. Her interest lies not in individual planets, a solar system or a galaxy, such as our Milky Way. Her research drive is oriented much more towards entire galactic clusters and the forces of nature that tell us something about the origin of the universe.

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    There are times when Heisenberg finds herself overwhelmed when looking at the billions of galaxies in the sky. “Curiosity was always the driving force for me,” she says on the Hönggerberg campus. “There is so much unknown out there. And we should just keep exploring.”

    Exciting times, mysterious forces

    For a physicist such as Heisenberg, who investigates the interaction between particle physics and cosmology, these are most certainly exciting times, with two major discoveries having significantly expanded the possibilities for research. A new particle, the Higgs boson, was discovered at CERN in July 2012.

    CERN CMS Higgs Event May 27, 2012.


    CERN ATLAS Higgs Event
    June 12, 2012.



    CERN map

    The first direct observation of gravitational waves was made in September 2015.

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

    MIT /Caltech Advanced aLigo .

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

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    Heisenberg is convinced that gravitational waves will open up further potential for discovery: “All the information so far that we have about the universe has only come through photons, through light. And now we also have this new channel of gravitational wave observations. You can compare it with a situation where we were completely blind, and now suddenly we can actually see all these beautiful colours.”

    Gravity is a key element in her research. “When you think of cosmological scales, of large scales, the gravitational force is the dominant one. So if you want to describe the nature or the physics behind the universe, you need to know what the fundamental law of gravity is,” she explains. “If you now combine precision measurements coming from gravitational waves with all the observations that we already had through light, at the end of the day we will come closer to what really is the true nature of gravity.” To date, a conclusive explanation has not been found. Approaches that describe the world on a large scale – i.e. in space – explain gravity differently than those approaches that describe the world on a small scale, i.e. in the innermost part of the atomic nucleus.

    These explanatory differences are based on the two great theoretical achievements of physics in the 20th century – the theory of relativity and quantum mechanics. The fact that it can still not be explained in a uniform way with a single theory makes gravitation the most mysterious of the four fundamental forces of physics. These basic forces determine the behaviour of bodies, fields, particles and systems; the other three are the weak interaction, the strong interaction and electromagnetism.

    Many perspectives, stable solutions

    Heisenberg’s approach is characterised by the way in which she studies gravity from a range of perspectives: like a telescope, each theory opens up another outlook on reality. She uses these perspectives to obtain new insights into the essential and fundamental properties of gravity. “We combine the various interpretations of gravity in order to find stable solutions to the problems of general relativity,” she adds. Heisenberg has now won the ETH Zurich Latsis Prize for her detailed analysis of gravity in the light of classical and quantum physics and the corresponding conclusions drawn from astrophysical, cosmological and particle physics experiments. The prize will be awarded at ETH Day 2020.

    Heisenberg’s multidisciplinary approach combines gravitational physics, cosmology, particle physics and computational astrophysics. As a theoretical physicist, she does not perform experiments in the lab or particle accelerators – she works with a pen and notebook, and carries out computer calculations. Mathematics is her most important tool. The quality of her theories is measured by the extent to which the mathematical equations can explain the data from particle physics experiments or from cosmological and astrophysical observations.

    Beethoven, bouldering and a bow and arrow

    Her multidisciplinary approach is reflected in the composition of her team and in her teaching. Heisenberg is a team player, and it is important to her to see open questions discussed: “I really enjoy interacting with my team and my students.” For her, enjoyment is the best compensation for disappointment and stress.

    Heisenberg also finds balance in running, climbing, fitness training and archery, and in activities that require a high level of concentration: “In archery I have to focus very closely on my position if I want to hit the target. In moments like these, I’m completely present in the here and now – not thinking about the past or worrying about the future.” She also experiences such inspiring moments of complete immersion in her research, moments when she is fully absorbed in what she is doing. In difficult times she finds stability in music, in the symphonies of Beethoven.

    Heisenberg’s career path is as diverse as her research: she has lived in various countries since childhood, “and in every country, I have learned the language.” Today she can speak six languages, including German. She originally arrived at ETH as a fellow of the Institute for Theoretical Studies. In 2018, she received an ERC Starting Grant, which is awarded only to the best researchers, and was appointed assistant professor in the Department of Physics. Her future is literally written in the stars – ever since she was a child, Heisenberg has dreamed of becoming an astronaut. And this goal continues to drive her: “To see Earth from such a perspective – it must be an amazing feeling to see how fragile our Earth is.”

    References

    Heisenberg L: A systematic approach to generalisations of General Relativity and their cosmological implications. [Physics Reports]

    Jiménez JB, Heisenberg L, Koivisto TS: [The Geometrical Trinity of Gravity].
    Heisenberg L: Generalization of the Proca Action. [Journal of Cosmology and Astroparticle Physics].

    See the full article here .

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    Please help promote STEM in your local schools.

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    ETH Zurich campus
    ETH Zürich (CH) is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zürich (CH) today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

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