Tagged: Axions Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 12:35 pm on May 25, 2021 Permalink | Reply
    Tags: "RADES at the CAST experiment joins the hunt for dark matter", , Axions, , , , , ,   

    From European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN]: “RADES joins the hunt for dark matter” 

    Cern New Bloc

    Cern New Particle Event

    From European Organization for Nuclear Research [Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN]

    25 May, 2021
    Ana Lopes

    1
    Researcher Sergio Arguedas Cuendis checking the RADES detector set-up at the CAST experiment [below]. (Image: CERN.)

    Long-hypothesised particles called axions could solve two problems in one strike: they could explain the puzzling symmetry properties of the strong force and they could make up the mysterious dark matter that permeates the cosmos. One of the newest detectors of the CAST experiment at CERN, RADES, has now joined the worldwide hunt for axions, searching for axions from the Milky Way’s “halo” of dark matter and setting a limit on the strength of their interaction with photons. The results are described in a paper submitted for publication in the Journal of High Energy Physics.

    One way of searching for axions from the Milky Way’s dark-matter halo is to look for their conversion into photons in a “resonating cavity”. If such axions surround and enter a resonating cavity that is placed in a strong magnetic field and resonates at a frequency corresponding to their mass, the chances of detecting them through their conversion into photons are increased.

    Many experiments have used this search method and set limits on the interaction strength of axions with two photons in the case of small axion masses, mainly below 25 µeV (for comparison, the proton mass is 1 GeV). Searching for larger axion masses using this approach requires a smaller cavity resonating at a higher frequency, but the smaller volume of a smaller cavity decreases the chances of spotting the particles.

    A workaround involves dividing the cavity into smaller cavities that resonate at a higher frequency and collectively don’t result in a loss of cavity volume. This is exactly the concept behind the RADES detector, which was installed inside one of CAST’s dipole magnet bores in 2018 and can search for axions from the Milky Way’s dark-matter halo that have a mass of around 34.67 µeV.

    Researchers are developing complementary approaches to searching for axions, and some have searched for larger-mass axions using new cavity designs and placed limits on their interaction strength with two photons. But the best limit so far for an axion mass of 34.67 µeV was placed by CAST’s previous searches for axions from the Sun.

    In its latest paper [above], the CAST team describes the results of the first RADES search for axions. Sifting through data taken for more than 100 hours within a period of 20 days in 2018, the team saw no signs of axions. However, the data places a limit on the interaction strength of axions with two photons in the case of axions with a mass of or close to 34.67 µeV – a limit that is more than 100 times more stringent than CAST’s previous best limit for this mass.

    “This result is a significant first step in the direct search for axions using dipole magnets,” says RADES scientist Sergio Arguedas Cuendis. “And as far as axion searches go, it’s one of the most stringent limits ever set for axions with masses above 25 µeV.”

    See the full article here.


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier


    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    ALICE

    CMS

    LHCb

    LHC

    OTHER PROJECTS AT CERN

    European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU)[CERN] AEGIS.


    CERN FASER is designed to study the interactions of high-energy neutrinos and search for new as-yet-undiscovered light and weakly interacting particles. Such particles are dominantly produced along the beam collision axis and may be long-lived particles, travelling hundreds of metres before decaying. The existence of such new particles is predicted by many models beyond the Standard Model that attempt to solve some of the biggest puzzles in physics, such as the nature of dark matter and the origin of neutrino masses.

     
  • richardmitnick 10:03 pm on April 12, 2021 Permalink | Reply
    Tags: "Sensitive qubit-based technique to accelerate search for dark matter", , Axions, , , , , ,   

    From DOE’s Fermi National Accelerator Laboratory(US) and From University of Chicago : “Sensitive qubit-based technique to accelerate search for dark matter” 

    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 world wide.

    and

    U Chicago bloc

    From University of Chicago

    April 12, 2021
    Steve Koppes

    Scientists at the Department of Energy’s Fermi National Accelerator Laboratory and the University of Chicago (US) have demonstrated a new technique based on quantum technology that will advance the search for dark matter, the invisible stuff that accounts for 85% of all matter in the universe.

    The collaboration has developed superconducting versions of devices called qubits that will be able to detect the weak signals emitted by two kinds of hypothetical subatomic particles that could reside in an invisible but ubiquitous part of the universe called the dark sector. One is called an axion, a leading dark matter candidate. The other is called a hidden photon, a particle that possibly interacts with the photons — particles of light — of the visible universe.

    1
    A qubit (the small rectangle) is set onto a sapphire substrate, which sits upon a fingertip to show scale. Fermilab and University of Chicago scientists used a qubit similar to this one to develop a technique that will speed up the search for axion dark matter and hidden photons. Photo: Reidar Hahn, Fermilab.

    The technique now demonstrated by the Fermilab-University of Chicago team is 36 times more sensitive to the particles than the quantum limit, a benchmark of conventional quantum measurements, enabling searches for dark matter to proceed 1,000 times faster.

    Using light to detect dark particles

    In the technique, the qubits are designed to detect the photons that would be produced when dark matter particles interact with an electromagnetic field. The benefit of using qubits as detectors instead of the conventional technology lies in the way they interact with photons.

    The key to the technique’s sensitivity is its ability to eliminate false-positive readings. Conventional techniques destroy the photons they measure. But the new technique can probe the photon without destroying it. Making repeated measurements of the same photon, over the course of its 500-microsecond lifetime, provides insurance against erroneous readings.

    “To make a measurement of the photon once with the qubit takes about 10 microseconds, so we can make about 50 repeated measurements of the same photon within its lifetime,” said Akash Dixit, a doctoral student in physics at the University of Chicago (US).

    Dixit and his co-authors, including Fermilab’s Aaron Chou, describe their technique in Physical Review Letters.

    “Experiments using conventional techniques were just nowhere near what they needed to be for us to be able to detect higher-mass axion dark matter,” Chou said. “The noise level is way too high.”

    There are two ways to make an experiment more sensitive to the subtle hints of new physics that the scientists are looking for. One is to boost the signal by making larger detectors. Another to reduce the noise levels that hide the target signals. The Fermilab-University of Chicago team did the latter.

    “It’s a much more clever and cheaper way to get the same large improvements in sensitivity,” Chou said. “Now, the level of the static noise has been reduced by so much that you have a chance to actually see the very first small wiggles in your measurements due to the very, very tiny signal.”

    The technique will benefit the search for any dark matter candidate because, when invisible particles convert into photons, they can be detected.

    “Where the conventional method may generate one photon of noise with every measurement, in our detector you get one photon of noise every thousand measurements you make,” Dixit said.

    Dixit and his colleagues adapted their technique from one developed by atomic physicist Serge Haroche, who shared the 2012 Nobel Prize in physics for his feat. Chou views the new technique as part of the progression that started with the development of nondemolition interaction in atomic physics and is now imported to the field of superconducting qubits.

    Ferreting out axions and hidden photons

    Physicists have made little progress in detecting axions since their existence was proposed more than 30 years ago.

    “We know that there’s a huge amount of mass all around us that isn’t made of the same stuff you and I are made of,” Chou said. “The nature of dark matter is a really compelling mystery that a lot of us are trying to solve.”

    Superconducting microwave cavities are vital to the new technique. The cavity used in the experiment is made of highly pure — 99.9999% — aluminum. At extremely low temperatures, the aluminum becomes superconducting, a property that extends the longevity of qubits, which by their nature are short-lived. The superconducting cavity provides a way to accumulate and store the signal photon. The qubit, an antenna inserted into the cavity, then measures the photon.

    2
    The blue cylinder in this diagram represents a superconducting microwave cavity used to accumulate a dark matter signal. The purple is the qubit used to measure the state of the cavity, either 0 or 1. The value refers to the number of photons counted. If the dark matter has successfully deposited a photon in the cavity, the output would measure 1. No deposition of a photon would measure 0. Image: Akash Dixit, University of Chicago.

    “The benefit we get is that, once you — or dark matter — puts a photon in the cavity, it’s able to hold the photon for a long time,” Dixit observed. “The longer the cavity holds the photon, the longer we have to make a measurement.”

    The same technique can find hidden photons and axions; the latter will require a high magnetic field to detect.

    If axions exist, the current experiment provides a one-in-10,000 chance that it would detect a photon produced by a dark matter interaction.

    “To further improve our ability to sense such a rare event, the temperature of the photons needs to be lowered,” said David Schuster, University of Chicago associate professor of physics and a co-author of the new paper. Lowering the photon temperature will further increase sensitivity to all dark matter candidates, including hidden photons.

    The photons in the experiment have been cooled to a temperature of approximately 40 millikelvins (minus 459.60 degrees Fahrenheit), just a touch above absolute zero. The researchers would like to go as low as the operating temperature of 8 millikelvins (minus 459.66 degrees Fahrenheit). At this point, the environment for searching for dark matter would be spotless, effectively free of background photons.

    “While there’s definitely still a ways to go, there’s reason to be optimistic,” said Schuster, whose research group will apply the same technology to quantum computing. “We’re using quantum information science to help the dark matter search, but the same kind of background photons are also a potential error source for quantum computations. So this research has uses beyond fundamental science.”

    Schuster said the project provides a nice example of the type of collaboration that makes sense to do between a university lab and a national lab.

    “Our university lab had the qubit technology, but in the long term by ourselves, we were not really able to do any kind of dark matter search at the level needed. That’s where the national-lab partnership plays an important role,” he said.

    The payoff from this cross-disciplinary effort could be huge.

    “There’s just no way to do these experiments without the new techniques that we developed,” Chou said.

    Funding for the experiment comes from the Heising-Simons Foundation and the DOE Office of Science through the High Energy Physics QuantISED program.

    See the full article here.


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: Argonne National Laboratory, Fermi National Accelerator Laboratory, and the Marine Biological Laboratory in Woods Hole, Massachusetts.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts. The University of Chicago is a private research university in Chicago, Illinois. Founded in 1890, its main campus is located in Chicago’s Hyde Park neighborhood. It enrolled 16,445 students in Fall 2019, including 6,286 undergraduates and 10,159 graduate students. The University of Chicago is ranked among the top universities in the world by major education publications, and it is among the most selective in the United States.

    The university is composed of one undergraduate college and five graduate research divisions, which contain all of the university’s graduate programs and interdisciplinary committees. Chicago has eight professional schools: the Law School, the Booth School of Business, the Pritzker School of Medicine, the School of Social Service Administration, the Harris School of Public Policy, the Divinity School, the Graham School of Continuing Liberal and Professional Studies, and the Pritzker School of Molecular Engineering. The university has additional campuses and centers in London, Paris, Beijing, Delhi, and Hong Kong, as well as in downtown Chicago.

    University of Chicago scholars have played a major role in the development of many academic disciplines, including economics, law, literary criticism, mathematics, religion, sociology, and the behavioralism school of political science, establishing the Chicago schools in various fields. Chicago’s Metallurgical Laboratory produced the world’s first man-made, self-sustaining nuclear reaction in Chicago Pile-1 beneath the viewing stands of the university’s Stagg Field. Advances in chemistry led to the “radiocarbon revolution” in the carbon-14 dating of ancient life and objects. The university research efforts include administration of DOE’s Fermi National Accelerator Laboratory(US) and DOE’s Argonne National Laboratory(US), as well as the U Chicago Marine Biological Laboratory in Woods Hole, Massachusetts (MBL)(US). The university is also home to the University of Chicago Press, the largest university press in the United States. The Barack Obama Presidential Center is expected to be housed at the university and will include both the Obama presidential library and offices of the Obama Foundation.

    The University of Chicago’s students, faculty, and staff have included 100 Nobel laureates as of 2020, giving it the fourth-most affiliated Nobel laureates of any university in the world. The university’s faculty members and alumni also include 10 Fields Medalists, 4 Turing Award winners, 52 MacArthur Fellows, 26 Marshall Scholars, 27 Pulitzer Prize winners, 20 National Humanities Medalists, 29 living billionaire graduates, and have won eight Olympic medals.

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics; establishing revolutionary theories of economics; and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts.

    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.

    FNAL Icon

    DOE’s Fermi National Accelerator Laboratory(US) Muon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

    FNAL Don Lincoln.

    FNAL DUNE LBNF (US) from FNAL to SURF, Lead, South Dakota, USA

     
  • richardmitnick 5:06 pm on February 11, 2021 Permalink | Reply
    Tags: "Dark-matter detector result is consistent with previous hint of exotic particles", Axions, , LUX-ZEPLIN detector, , PandaX-II particle detector, , The events reported in 2020 involved electron rather than nuclear recoils., , XENON1T Dark Matter experiment   

    From physicsworld.com: “Dark-matter detector result is consistent with previous hint of exotic particles” 

    From physicsworld.com

    09 Feb 2021
    Edwin Cartlidge

    PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

    New data from the PandaX-II particle detector in China leave open the possibility that the XENON1T experiment in Italy has found evidence of new physics.

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

    In June 2020 researchers working on XENON1T announced the detection of around 50 events above background levels and concluded that hypothetical solar axions or very magnetic neutrinos might be responsible. The new results from PandaX-II are consistent with these hypotheses but further work will be needed to settle the issue.

    XENONIT was built to hunt for a type of dark matter known as weakly interacting massive particles (WIMPs). Housed under a mountain at Italy’s Gran Sasso National Laboratory, it contained 3.5 tonne of liquid xenon and operated between 2016-2018. Like other experiments of its type, it was designed to pick up the tiny flashes of light generated when WIMPs in the “halo” of dark matter thought to envelop the Milky Way collide with xenon nuclei.

    The events reported in 2020 involved electron, rather than nuclear, recoils. Elena Aprile of Columbia University in the US and colleagues reported 53±15 such recoils at low energy that they could not tie to other identifiable sources of background (these events themselves being considered noise in the search for WIMPs). Careful not to claim any discovery, they instead laid out several possible explanations for the observation.

    Two novelties

    These explanations included two novelties associated with particles arriving from the Sun – either hypothetical particles known as axions (postulated originally to fix a problem with the strong nuclear force) or neutrinos with a greater magnetic moment than previously observed. Another possibility, they said, was “bosonic dark matter”, which would be absorbed, rather than scattered, by the xenon nuclei and cause electrons to be emitted.

    However, as Aprile and colleagues pointed out, the events could also have had a more mundane explanation – the beta decay of tritium nuclei. This would come about when the few neutrons liberated from surrounding rock by cosmic rays create tritium by splitting xenon nuclei. Unlike other background processes, this remains a nuisance since its extent is not possible to estimate reliably.

    Aprile and colleagues calculated that the tritium could account for the excess events with a statistical significance of 3.2σ – compared to 3.4σ, 3.2σ and 3.0σ for solar axions, neutrino magnetism and bosonic dark matter, respectively.

    Dimmer white dwarfs

    Despite their cautious presentation, these results caught the attention of both the public and fellow physicists. For example, theorists put forward several ways to overcome one obvious sticking point with the Sun-based hypotheses – that the flux of the particles involved would make white dwarf stars dimmer than they appear.

    In the latest work, Jianglai Liu of Shanghai Jiao Tong University (CN) and colleagues did an independent experimental check on the XENON1T results using the PandaX-II detector in the China Jinping Underground Laboratory in Sichuan, south-western China. Although PandaX-II contains just over half a tonne of xenon, the researchers ran their experiment for longer and acquired nearly half the data as their XENON1T counterparts.

    The Chinese group had the advantage of being able to better characterize their background spectra, thanks to direct measurement or calibration. In part, this was done by twice injecting methane with one of its hydrogen atoms replaced by tritium into the target. With the two injections carried out three years apart, they say they were able to measure the energy spectrum of the tritium contamination within the experiment.

    By in effect subtracting the background spectra of tritium, krypton and radon, the researchers were able to quantify any signals from putative solar axions or a high neutrino magnetic moment – the two theoretical possibilities that Liu says the group used as a “benchmark” in their work. As they report in Chinese Physics Letters, they found that the remaining electron recoils were in fact consistent with the excess events seen by XENON1T. However, they could not fully endorse the earlier result given, they say, that their data were also consistent with a “background-only hypothesis”.

    Detector upgrades

    To try and establish whether some new physical process really has been observed, the Chinese researchers are increasing their detector mass to 6 tonne – meaning a sensitive target of 4 tonne – while lowering background rates. The upgraded detector is called PandaX-4T and should start taking data this year. Also coming online are an upgraded 8.3 tonne “XENONnT” as well as the 10 tonne LUX-ZEPLIN detector currently being installed in the Sanford Underground Research Facility in South Dakota, US.

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA.


    LUX-ZEPLIN LBNL xenon detector at SURF. Credit: Matt Kapust.

    According to Liu, the new measurements should yield a verdict soon. “A year of low background data taking from PandaX-4T would be able to offer a definitive answer to the XENON1T excess,” he says, although he adds that it remains to be seen just how low they can make the background.

    One group already has an explanation for the XENON1T excess [Physical Review D] – and it does not rely on exotic new physics. Matthew Szydagis, Cecilia Levy and colleagues at the State University of New York at Albany used what is known as the noble element simulation technique to model background interactions within the Gran Sasso detector and found that around 30 decays of the isotope argon-37 would generate the observed excess.

    Levy says that their hypothesis could be investigated by carrying out a thorough calibration of the XENON detector, adding that her group does not know where the argon might come from. Beyond that, she agrees that the observed excess should be scrutinized by the new round of larger experiments. “If it is due to a new particle, it should predictably scale with the more massive detectors,” she says, “and a signal should be clear.”

    Levy says that their hypothesis could be investigated by carrying out a thorough calibration of the XENON detector, adding that her group does not know where the argon might come from. Beyond that, she agrees that the observed excess should be scrutinized by the new round of larger experiments. “If it is due to a new particle, it should predictably scale with the more massive detectors,” she says, “and a signal should be clear.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

     
  • richardmitnick 6:09 pm on January 23, 2021 Permalink | Reply
    Tags: "Seven Unique Neutron Stars May Shed Light On Dark Matter", A group of scientists have studied a group of seven neutron stars which are emitting an unexplained amount of high energy x-rays and have come up with a possible explanation for the observation., A nearby group of seven neutron stars is called the Magnificent Seven., Axions, Axions are a particle proposed to solve an unexplained behavior of the strong force, , , If dark matter exists and is in the form of a theoretical subatomic particle called axions then a specific class of neutron stars would be an ideal laboratory in which to find it., , So how do dark matter axions and neutron stars connect?, which is responsible for holding protons and neutrons together in the center of atoms.   

    From Forbes Magazine: “Seven Unique Neutron Stars May Shed Light On Dark Matter” 

    From Forbes Magazine

    Jan 22, 2021

    Don Lincoln-Fermi National Accelerator Laboratory.

    1
    Computer generated image of a neutron star, including surrounding magnetic fields. Quiescent neutron stars are an ideal laboratory to search for a possible form of dark matter. Credit: Getty.

    Neutron stars are the smallest known variety of stars, containing the densest form of matter known to man. And, according to a recent paper published in Physical Review Letters, they may also be an ideal laboratory in which to discover dark matter.

    Neutron stars are formed when stars between one and three times the sun run out of fuel and collapse in under the force of gravity. This gravitational attraction pushes the electrons of atoms into the protons, turning them into neutrons. The result is an object about ten to fifteen miles in diameter, essentially a huge atomic nucleus with the diameter of a mid-sized city, consisting essentially entirely of neutrons.

    Dark matter is thought to be a form of matter that both experiences and causes gravity but does not emit any form of electromagnetic radiation – light, heat, radio waves, nothing. There is substantial astronomical evidence that dark matter exists, but it has never been directly observed and thus scientists don’t have any idea of its detailed properties. Current thinking is that it is a stable and electrically neutral subatomic particle, but the mass of individual dark matter particles is not known.

    A group of scientists have studied a group of seven neutron stars which are emitting an unexplained amount of high energy x-rays and have come up with a possible explanation for the observation. If dark matter exists and is in the form of a theoretical subatomic particle called axions, then a specific class of neutron stars would be an ideal laboratory in which to find it.

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

    CERN CAST Axion Solar Telescope.

    Axions are a particle proposed to solve an unexplained behavior of the strong force, which is responsible for holding protons and neutrons together in the center of atoms. In principle, the force could favor matter over antimatter or vice versa, but it doesn’t. There needs to be a reason that this possible behavior doesn’t occur and the axion particle was proposed to solve this mystery. If the axion exists, the strong nuclear force should treat matter and antimatter equally. Note that the axion is a theoretical particle that hasn’t been discovered.

    But, if the axion >>does<< exist, it could also be dark matter. So how do dark matter axions and neutron stars connect?

    A nearby group of seven neutron stars is called the Magnificent Seven. Like all neutron stars, they generate powerful magnetic fields. However, unlike many neutron stars, they are extraordinarily quiescent. They emit soft (e.g. low energy) x-rays and ultraviolet light. In essence, they are quiet and dull, which is very important for axion searches, as it makes it easier to look for small unexpected excesses of other forms of light.

    Neutron stars are made almost exclusively of neutrons. These neutrons move around inside the star, bumping into one another. When they interact, they emit neutrinos. Neutrinos are well-known, low mass particles that then escape the neutron star. They are emitted in nuclear reactions, like inside nuclear power plants or the sun.

    If axions exist, they will also be created like neutrinos. Axions are also low mass, electrically neutral, particles and they will also escape the neutron star. However, unlike neutrinos, which escape totally unscathed, axions can interact with the magnetic field surrounding the neutron star and convert into photons, specifically hard (e.g. high energy) x-rays.

    In a recent paper [The Astrophysical Journal], astronomers studied the Magnificent Seven and found that all emitted the expected amount of soft x-rays and ultraviolet light, however, two of the seven also emitted a significant amount of unexplained amount of hard x-rays.

    In a second paper [Physical Review Letters], a group of researchers (some of whom were authors of both papers) proposed that the excess of hard x-rays could be explained by axion emission.

    It is important to be cautious. The authors did not claim that they have observed axions, merely that the axion hypothesis could explain the unexplained hard x-rays.

    It’s also worth noting that the unexplained hard x-rays were definitively observed in only two of the seven neutron stars. Two of the remaining five appeared to possibly also be emitting hard x-rays, although the data was inconclusive. Two others had spectra that could possibly indicate the emission of hard x-rays, but the signal was weak and could easily be spurious. The remaining star actually had a slight deficit of hard x-ray emission. If the axion explanation is correct, scientists will need to understand why the different stars had different amounts of hard x-ray emission.

    It is more probable that the hard x-rays originating from of the Magnificent Seven can be explained by a more ordinary (although still explained) astronomical phenomenon. To be sure that the axion explanation is correct, researches will have to generate and detect axions in a laboratory here on Earth. There are many ongoing experiments, ranging from ones searching for axions from space, to others trying to generate them in particle beams.

    Researches will continue to search for other possible signatures of cosmic axions.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 5:53 pm on December 21, 2020 Permalink | Reply
    Tags: "Looking for dark matter near neutron stars with radio telescopes", , Axions, “the Strong CP problem”, , , , ,   

    From The Kavli Institute for the Physics and Mathematics of the Universe – University of Tokyo (JP): “Looking for dark matter near neutron stars with radio telescopes” 

    KavliFoundation

    From The Kavli Institute for the Physics and Mathematics of the Universe – University of Tokyo (JP)

    Kavli IPMU

    December 18, 2020

    1
    Figure 1. illustrates the CP symmetry operation performed upon a meson particle. We say that the CP symmetry is violated if we observe that the original system (first frame in Fig.1) decays into a different particle than the CP transformed system (fourth frame in Fig.1). Credit: Kavli IPMU.

    In the 1970s, physicists uncovered a problem with the Standard Model of particle physics—the theory that describes three of the four fundamental forces of nature (electromagnetic, weak, and strong interactions; the fourth is gravity). They found that, while the theory predicts that a symmetry between particles and forces in our Universe and a mirror version should be broken, the experiments say otherwise. This mismatch between theory and observations is dubbed “the Strong CP problem”—CP stands for Charge+Parity. What is the CP problem, and why has it puzzled scientists for almost half a century?

    In the Standard Model, electromagnetism is symmetric under C (charge conjugation), which replaces particles with antiparticles; P (parity), which replaces all the particles with their mirror image counterparts; and, T (time reversal), which replaces interactions going forwards in time with ones going backwards in time, as well as combinations of the symmetry operations CP, CT, PT, and CPT. This means that experiments sensible to the electromagnetic interaction should not be able to distinguish the original systems from the ones that have been transformed by either of the aforementioned symmetry operations.

    In the case of the electromagnetic interaction, the theory matches the observations very well. As anticipated, the problem lays in one of the two nuclear forces—“the strong interaction.” As it turns out, the theory allows violations of the combined symmetry operation CP (reflecting particles in a mirror and then changing particle for antiparticle) for both the weak and strong interaction. However, CP violations have so far been only observed for the weak interaction.

    More specifically, for the weak interactions, CP violation occurs at approximately the 1-in-1,000 level, and many scientists expected a similar level of violations for the strong interactions. Yet experimentalists have looked for CP violation extensively but to no avail. If it does occur in the strong interaction, it’s suppressed by more than a factor of one billion (10⁹).

    In 1977, theoretical physicists Roberto Peccei and Helen Quinn proposed a possible solution: they hypothesized a new symmetry that suppresses CP-violating terms in the strong interaction, thus making the theory match the observations. Shortly after, Steven Weinberg and Frank Wilczek—both of whom went on to win the Nobel Prize in physics in 1979 and 2004, respectively—realized that this mechanism creates an entirely new particle. Wilczek ultimately dubbed this new particle the “axion,” after a popular dish detergent with the same name, for its ability to “clean up” the strong CP problem.

    The axion should be an extremely light particle, be extraordinarily abundant in number, and have no charge. Due to these characteristics, axions are excellent dark matter candidates. Dark matter makes up about 85 percent of the mass content of the Universe, but its fundamental nature remains one of the biggest mysteries of modern science. Finding that dark matter is made of axions would be one of the greatest discoveries of modern science.

    In 1983, theoretical physicist Pierre Sikivie found that axions have another remarkable property: In the presence of an electromagnetic field, they should sometimes spontaneously convert to easily detectable photons. What was once thought to be completely undetectable, turned out to be potentially detectable as long as there is high enough concentration of axions and strong magnetic fields.

    Some of the Universe’s strongest magnetic fields surround neutron stars. Since these objects are also very massive, they could also attract copious numbers of axion dark matter particles. So physicists have proposed searching for axion signals in the surrounding regions of neutron stars. Now, an international research team, including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) postdoc Oscar Macias, has done exactly that with two radio telescopes—the Robert C. Byrd Green Bank Telescope in the US, and the Effelsberg 100-m Radio Telescope in Germany.

    2
    Green Bank Telescope (Credit: GBO / AUI / NSF) in West Virginia, USA.

    MPIFR/Effelsberg Radio Telescope, in the Ahrgebirge (part of the Eifel) in Bad Münstereifel, Germany.

    The targets of this search were two nearby neutron stars known to have strong magnetic fields, as well as the Milky Way’s center, which is estimated to host half a billion neutron stars. The team sampled radio frequencies in the 1-GHz range, corresponding to axion masses of 5–11 micro electron-volt. Since no signal was seen, the team was able to impose the strongest limits to date on axion dark matter particles of a few micro electron-volt mass.

    Science paper:
    Green Bank and Effelsberg Radio Telescope Searches for Axion Dark Matter Conversion in Neutron Star Magnetospheres
    Physical Review Letters

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

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

    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

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

     
  • richardmitnick 3:12 pm on December 11, 2020 Permalink | Reply
    Tags: "Search for invisible axion dark matter with a multiple-cell cavity", Axions, Cavity haloscope, , Institute for Basic Science [ 기초과학연구원] (KR), , Pizza cavity   

    From Institute for Basic Science [ 기초과학연구원] (KR) via phys.org: “Search for invisible axion dark matter with a multiple-cell cavity” 

    From Institute for Basic Science [ 기초과학연구원] (KR)

    via


    phys.org

    December 11, 2020

    1
    Figure 1. Cavity designs with various internal sections. (Left to right) (1) single large cavity, (2) single small cavity, (3) multiple small cavities (4) multiple-cell cavity (pizza cavity) (5) multiple-cell cavity with a gap . Credit: IBS.

    Despite its vanishingly tiny mass, the existence of the axion, once proven, may point to new physics beyond the Standard Model.

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

    Theorized to explain a fundamental symmetry problem in the strong nuclear force associated with the matter-antimatter imbalance in our universe, this hypothetical particle also makes an attractive Dark Matter candidate. Though axions would exist in vast enough numbers to be able to account for the “missing” mass from the universe, the search for this dark matter has been quite challenging so far.

    Scientists believe that when an axion interacts with a magnetic field, its energy would be converted into a photon. The resulting photon is expected to be somewhere in the microwave-frequency range. Hoping to hit the right match for the axion, experimentalists use a microwave detector, a cavity haloscope. Having a cylindrical resonator placed in a solenoid, the magnetic field filling the cavity enhances the signal. The haloscope also allows scientists to continually adjust the resonant frequency of the cavity. However, the most sensitive axion-search experiment, the Axion Dark Matter eXperiment (ADMX) at the University of Washington has been searching low frequency regions, below 1 GHz, as scanning higher frequency regions requires a smaller cavity radius, resulting in significant volume loss and hence less signal. (Figure 1-(2))

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

    A research team, led by Dr. YOUN SungWoo at the Center for Axion and Precision Physics Research (CAPP) within the Institute for Basic Science (IBS) in South Korea, has developed a novel multiple-cell cavity design, dubbed “pizza cavity.” Just like pizzas are cut into several slices, multiple partitions vertically divide the cavity volume into identical pieces (cells). With almost no volume to be lost, this multiple-cell haloscope enables the meaningful output of high-frequency region scanning. (Figure 1-(5)). Though there were endeavors to bundle smaller cavities together and combine individual signals with all the cavities tuned at the same frequency, its complicated setup and non-trivial frequency matching mechanism have been bottlenecks. (Figure 1-(3)). “The pizza cavity haloscope features a simpler detector setup and a unique phase-matching mechanism as well as a larger detection volume compared to the conventional multi-cavity design,” notes Dr. YOUN SungWoo, the corresponding author of the study.

    3
    Figure 2. Cross-sectional view of various multiple-cell (double-, quadruple- and octuple-cell) cavities with the expected distribution of the axion-induced electric field (from simulation). Credit: IBS.

    The researchers proved that the multiple-cell cavity was able to detect high-frequency signals with improved efficiency and reliability. In an experiment using a 9T-superconducting magnet at a temperature of 2 kelvin (−271 °C), the team quickly scanned a frequency range of > 200 MHz above 3 GHz, which is 4~5 times higher region than that of ADMX yielding higher sensitivity to theoretical models than the previous results made by other experiments. Also this new cavity design enabled the researchers to explore a given frequency range four times faster than a conventional experiment could. “Getting things done four times faster.” Dr. Youn jokingly adds, “Using this multiple-cell cavity design, our Ph.D. students should be able to graduate faster than those in other labs.”

    What makes this multiple-cell design simple to operate is the gap between partitions in the middle. Having all of the cells spatially connected, a single antenna picks up the signal from the entire volume. “As a pizza saver keeps pizza slices intact with its original toppings, the gap in between helps the cells to be up to the job,” says Dr. Youn. The single antenna also allows researchers to assess whether the axion-induced electromagnetic fields are evenly distributed throughout the cavity, which is found to be critical to achieve the maximum effective volume. “Still, the inaccuracy and misalignment in cavity construction could hamper the sensitivity. For that, this multiple-cell design enables to relieve it by adjusting the size of the gap in the middle, leaving no volume to go to waste,” explains Dr. Youn.

    The two-year extensive efforts of the research team resulted in an optimal design for long-sought search of axion dark matter in high-frequency regions. The team is looking into incorporating several multiple-cell cavities onto the existing systems at CAPP to extend the axion search band to higher-frequency regions than currently explored.

    Science paper:
    Search for Invisible Axion Dark Matter with a Multiple-Cell Haloscope
    Physical Review Letters

    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, did most of the work on Dark Matter.

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

    Coma cluster via NASA/ESA Hubble.

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

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

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

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


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


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.

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

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

    See the full article here.

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Institute for Basic Science [ 기초과학연구원] (KR)

    Accelerate Transformation through New Knowledge

    IBS was established in November 2011 as Korea’s first dedicated basic science research institute. By studying the fundamental principles of nature, basic science is essential in creating new knowledge from which significant societal transformations are derived. IBS promotes the highest quality of research that will increase the national basic science capacity and generate new opportunities for this nation.

    IBS specializes in long-term projects that require large groups of researchers. As research in the 21st century requires more interdisciplinary collaborations from larger groups of people, scientists at IBS work together in the same laboratory base with a long-term perspective on research. We promote autonomy in research. IBS believes scientists unleash their creative potential most effectively when they conduct research in an autonomous environment with world-class research infrastructure, including RISP, the rare isotope accelerator, to enable major scientific advances. By developing strong synergies from outstanding talents, autonomous research support systems, and world-class infrastructure, IBS is steadily growing into a major basic research institute that meets the global standards of excellence.
    Ensure Excellence in Research

    By pursuing excellence in research, IBS has selected global leading scientists as directors of Centers. These directors are operating 31 Centers of which research proposals are evaluated superior in the IBS peer review process. The review is carried out by a Review Panel composed of independent and expert scientists from Korea and abroad. Directors choose the themes of their research and allocate funds accordingly. Generally, Centers operate projects with no fixed term for their duration as long as the quality of research is verified in evaluations. New Centers receive an initial evaluation five years after its launch, followed by three-year interval evaluations.

    IBS has been inviting top scientists from around the globe and providing them full support for their relocations. Young scientists also enjoy unique research opportunities to collaborate with world renowned scientists and to organize and operate their own research groups, broadening their professional expertise. IBS brings together outstanding talents throughout all career levels to grow and inspire each other through close collaborations.
    Stimulate Collaboration Without Boundaries

    IBS welcomes scientists from Korea and abroad seeking to work in a collaborative research environment. IBS’ faculty researcher program and IBS’s affiliation with the founding body of University of Science and Technology (UST) help IBS scientists to reach out to and foster young talent outside the institution. Centers serve as a catalyst for research collaboration with universities and other government-funded research institutions through joint research and the sharing of research equipment. Other efforts are also underway to stimulate collaborations, including overseas training programs and visiting scientist programs.

    To disseminate research findings, IBS holds “IBS Conferences” and develops a global network with the world’s prominent research institutions including the Max Planck Gesellschaft (MPG) in Germany and the Royal Society in U.K. We expect our work to make transformative changes outside as well as inside the institution. To realize this exciting vision, IBS will serve as a national R&D platform and accelerate the creation and use of new knowledge to support universities, research institutions, and businesses. As a driving force for dynamic research collaborations, IBS will continually develop and refresh its science, while always remaining receptive to outside talents and ideas.
    Continue its Endeavor to Make a Brighter Future

    IBS shares the same passion as other great minds to investigate the origin of the universe, nature, and life for the development of humanity, as shown in its vision “Masking Discoveries for Humanity & Society”. We are committed to realizing this vision through a phased endeavor as outlined in our Five-year Plan (2013 – 2017). We aim to:

    Become a national hub for basic science research by 2017
    Complete the construction of the rare isotope accelerator by 2021
    Evolve into one of the world’s top 20 basic research institution by 2030 (measured in terms of impact on research).

    Serving as a stimulus for the innovation, IBS HQ will evolve into an urban science park that will promote public outreach and community engagement. Our commitment to enhance the quality of life and make sustainable progress continues every day.

     
  • richardmitnick 11:38 pm on December 3, 2020 Permalink | Reply
    Tags: "Pulling the secrets of dark matter out of a hat", ABRACADABRA-“A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus”, Axions, , , Grad student Chiara Salemi and Professor Lindley Winslow, ,   

    From MIT News: “Pulling the secrets of dark matter out of a hat” Grad student Chiara Salemi and Professor Lindley Winslow 

    MIT News

    From MIT

    December 2, 2020
    Fernanda Ferreira

    1
    Chiara Salemi, with ABRACADABRA open, shows the magnet inside.
    Credits: Jon Ouellet.

    Grad student Chiara Salemi and Professor Lindley Winslow use the ABRACADABRA instrument to reveal insights into dark matter.

    On the first floor of MIT’s Laboratory for Nuclear Science hangs an instrument called “A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus,” or ABRACADABRA for short. As the name states, ABRACADABRA’s goal is to detect axions, a hypothetical particle that may be the primary constituent of dark matter, the unseen and as-of-yet unexplained material that makes up the bulk of the universe.

    For Chiara Salemi, a fourth-year physics graduate student in the group of Lindley Winslow, the Jerrold R. Zacharias Career Development Associate Professor of Physics, ABRACADABRA is the perfect instrument to work on during her PhD. “I wanted a small experiment so I could do all the different pieces of the experiment,” Salemi says. ABRACADABRA, which consists of an extremely well-shielded magnet, is the size of a basketball.

    Salemi’s willingness to work on all aspects is unique. “Experimental physics roughly has three components: hardware, computation, and phenomenology,” Winslow explains, with students leaning toward one of the three. “Chiara’s affinity and strengths are evenly distributed across the three areas,” Winslow says. “It makes her a particularly strong student.”

    Since beginning her PhD, Salemi has worked on everything from updating ABRACADABRA’s circuitry for its second run to analyzing the instrument’s data to look for the first sign of a dark matter particle.

    A happy accident

    When Salemi started college, she wasn’t planning on pursuing physics. “I was leaning towards science, but I wasn’t totally sure of that or what field within science I would like.” During her first semester at the University of North Carolina at Chapel Hill, she took physics with the aim of determining whether this might be a field she might be interested in. “And then, I just totally fell in love with it, because I started doing research, and research is fun.”

    Throughout her undergraduate career, Salemi collected research experiences. She operated radio telescopes in West Virginia.

    Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF, supported by Breakthrough Listen.

    She spent a semester in Geneva, Switzerland, looking for Higgs boson decays at the European Organization for Nuclear Research, better known as CERN.


    CERN map


    SixTrack CERN (CH) LHC particles.

    At the Lawrence Berkeley National Laboratory, she tinkered with the design of semiconductors for the detection of neutrinos.

    It was at one of these research experiences, a summer program at Fermilab in Illinois, that she began working with axions.

    FNAL Wilson Hall

    “Like many things in life, it was an accident.”

    Salemi had applied for the summer program because she wanted to continue working on neutrinos and “Fermilab is the hub of all things neutrino.”

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

    But when she got there, Salemi found out that she was assigned to work on axions. “I was extremely disappointed, but I ended up falling in love with axions, because they’re really interesting and different from other particle physics experiments.”

    Elementary particles in the universe and the forces that regulate their interactions are explained by the Standard Model of particle physics.

    Standard Model of Particle Physics via http://www.plus.maths.org .

    The name belies the importance of this theory; the Standard Model, which was developed in the early 1970s, describes almost everything in the subatomic world. “But there are some huge gaping holes,” Salemi says. “And one of these huge gaping holes is Dark Matter.”

    Dark matter is matter we cannot see. Unlike normal matter, which interacts with light — absorbing it, reflecting it, emitting it — dark matter does not or only barely interacts with light, making it invisible to both the naked eye and current instruments. Its existence is deduced by its impact on visible matter. Despite its invisibility, dark matter is vastly more abundant, Salemi says. “There’s five times more dark matter in the universe than normal matter.”

    Like its visible counterpart, which is made up of particles such as neutrons, protons, and electrons, dark matter is also made up of particles, but physicists still don’t know exactly what types. One candidate is the axion, and ABRACADABRA was designed to find it.

    Small but mighty

    Compared to CERN’s Large Hadron Collider, which is an instrument tasked with detecting proposed particles and has a circumference of 16.6 miles, ABRACADABRA is tiny. For Salemi, the instrument is representative of a new era of tabletop physics. Creating ever-larger instruments to quest after increasingly elusive particles had been the go-to strategy, but these have become increasingly expensive. “Because of that, people are coming up with all sorts of really interesting ideas on how to still make discoveries, but on a smaller budget,” Salemi says.

    The design of ABRACADABRA was developed in 2016 by three theorists: Jesse Thaler, an associate professor of physics; Benjamin Safdi, then an MIT Pappalardo Fellow; and Yonatan Kahn PhD ’15, then a graduate student of Thaler’s. Winslow, an experimental particle physicist, took that design and figured out how to make it a reality.

    ABRACADABRA is composed of a series of magnetic coils in the shape of a toroid — picture an elongated donut — wrapped in a superconducting metal and kept refrigerated at around absolute zero. The magnet, which Salemi says is about the size of a large grapefruit, generates a magnetic field around the toroid but not in the donut hole. She explains that, should axions exist and interact with the magnetic field, a second magnetic field will appear within the donut hole. “The idea is that that would be a zero-field region, unless there’s an axion.”

    It can take 10 or more years to take a theoretical design for an experiment and make it operational. ABRACADABRA’s journey was much shorter. “We went from a theoretical paper published in September 2016 to a result in October 2018,” Winslow says. The geometry of the toroidal magnet, Winslow says, provides a naturally low background region, the donut hole, in which to search for axions. “Unfortunately, we have gotten through the easy part and now have to reduce those already-low backgrounds,” says Winslow. “Chiara led the effort to increase the sensitivity of the experiment by a factor of 10,” says Winslow.

    To detect a second magnetic field generated by an axion, you need an instrument that is incredibly sensitive, but also shielded from external noise. For ABRACADABRA, that shielding comes from the superconducting material and its frigid temperature. Even with these shields, ABRACADABRA can detect people walking in the lab and even pick up radio stations from around Boston, Massachusetts. “We can actually listen to the station from our data,” Salemi says. “It’s like the most expensive radio.”

    If an axion signal is detected, Salemi and colleagues will first try hard to disprove it, looking for all potential sources of noise and eliminating them one by one. According to Salemi, detecting dark matter means awards, even a Nobel Prize. “So you don’t publish that kind of result without spending a very long time to make sure it’s correct.”

    Results from ABRACADABRA’s first run were published in March 2019 in Physical Review Letters by Salemi, Winslow, and others in MIT’s Department of Physics. No axions were detected, but the run pointed out tweaks the team could make to increase the instrument’s sensitivity prior to its second run that began in January 2020. “We have been working on setting up, running, and analyzing run 2 for about a year and a half,” says Salemi. Currently, all the data has been collected and the group is finishing up the analysis. The results of which will be published later this year.

    As they prepare those results for publication, Salemi and her colleagues are already thinking of the next generation of axion detectors, called DM Radios, for Dark Matter Radios. Salemi says that this will be a much larger, multi-institute collaboration, and the design of the new instrument is still being conceived, including deciding the shape of the magnet. “We have two possible designs: One is the donut shape, and the other one is a cylinder shape.”

    The search for axions began in 1977, when they were first theorized, and since the 1980s experimental physicists have been designing and improving instruments for detecting this elusive particle. For Salemi, it would be amazing to continue working on axions through to their discovery, although no one can predict when that may happen. “But, seeing experimental low-mass axion dark matter through from around the start to the finish? That I could do,” she says. “Fingers crossed.”

    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, did most of the work on Dark Matter.

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

    Coma cluster via NASA/ESA Hubble.

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

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

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

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).


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


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.

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

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

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    USPS “Forever” postage stamps celebrating Innovation at MIT.

    MIT Campus

     
  • richardmitnick 9:31 am on November 13, 2020 Permalink | Reply
    Tags: "Dark-matter candidate could display stringy effects in the lab", , Axions, , ,   

    From RIKEN (JP): “Dark-matter candidate could display stringy effects in the lab” 

    RIKEN bloc

    From RIKEN (JP)

    Nov. 13, 2020

    Calculations show how theoretical ‘axionic strings’ could create odd behavior if produced in exotic materials in the lab.

    1
    An artist’s impression of an axion, a hypothetical elementary particle, which has been invoked to explain why charge–parity symmetry is preserved in quantum chromodynamics. They have since been proposed as a leading candidate for dark matter. © RAMON ANDRADE 3DCIENCIA/SCIENCE PHOTO LIBRARY.

    A hypothetical particle that could solve one of the biggest puzzles in cosmology just got a little less mysterious. A RIKEN physicist and two colleagues have revealed the mathematical underpinnings that could explain how so-called axions might generate string-like entities that create a strange voltage in lab materials1.

    Axions were first proposed in the 1970s by physicists studying the theory of quantum chromodynamics, which describes how some elementary particles are held together within the atomic nucleus. The trouble was that this theory predicted some bizarre properties for known particles that are not observed. To fix this, physicists posited a new particle—later dubbed the axion, after a brand of laundry detergent, because it helped clean up a mess in the theory.

    Physicists soon realized axions could clear up a cosmic conundrum too. More than 80% of the matter in the Universe is thought to be made up of a mysterious invisible substance, dubbed dark matter. “Axions are a candidate for dark matter, but we have not found them yet,” says Yoshimasa Hidaka, of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program. Axions might have the right properties, so physicists have been searching for signs they exist in numerous experiments. In June 2020, the XENON1T experiment at the Gran Sasso Laboratory in Italy reported hints they may have detected the axion—but that result has yet to be confirmed.

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


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

    But there is another arena where axion properties can be studied. Physicists can prepare exotic materials—called topological insulators—in the lab, which display strange properties, such as conducting electricity on their surfaces while remaining electrical insulators within. Such materials display other weird behavior. Sometimes, their electrons group together and move in such a way that the material appears to be made from ‘quasiparticles’ with unusual properties. This can create an unexpected voltage across the material, called the anomalous Hall effect.

    The axion is also predicted to arise in this way, in topological insulators, where it should interact with particles of light, or photons, in a different way to regular particles.

    Hidaka and his two colleagues have now examined the theory governing the interaction between axions and photons. Even though axions are point-like particles, the team calculated that within materials, light actually interacts with extended thread-like configurations made of axions, called axionic strings. That would lead to the anomalous Hall effect, which is observed in experiments.

    “We have found the underlying mathematical structure for the phenomenon,” says Hidaka.

    Science paper:
    Higher-form symmetries and 3-group in axion electrodynamics
    Physics Letters B

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    RIKEN campus

    RIKEN (JP) is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 9:15 am on June 25, 2020 Permalink | Reply
    Tags: "A Startling Excess of Particle Detections by the XENON1T Could Point to New Physics", Axions, , , , Researchers confidently expected 232 triggering events—no more no less. Yet XENON1T racked up a surprising excess of 285 particle detections., , U Chicago Kavli Institute for Cosmological Physics   

    From The Kavli Foundation: “A Startling Excess of Particle Detections by the XENON1T Could Point to New Physics” 

    KavliFoundation

    From The Kavli Foundation

    06/17/2020
    Adam Hadhazy

    1
    Experts construct the top PMT array. Image courtsey of XENON collaboration.​

    A strange thing happened while running the most sensitive dark matter detector built to date, known as XENON1T. Having painstakingly accounted for all known sources of particles that could trigger the exquisitely sensitive apparatus, researchers confidently expected 232 triggering events—no more, no less. Yet XENON1T racked up a surprising excess of 285 particle detections. Researchers are cautiously elated by the findings, announced earlier this week, which could point to brand-new physics.

    To be clear, the eyebrow-raising excess does not match the signal for Dark Matter—XENON1T’s primary quarry, a theoretical substance that constitutes as much as 85 percent of the matter in the cosmos. But on the short list of three conceivable candidates behind the excess, two would represent breakthroughs of their own in physics. The pedestrian candidate is a miniscule trace of tritium, a radioactive form of hydrogen, inside the detector. More likely, however, is a never-before-seen type of particle, called a solar axion, pumped out by the Sun. The final possibility: an undiscovered property of neutrinos, the ubiquitous and ghostly particles that pass through every square centimeter of Earth—including our bodies—by the trillions every second.

    However the excess shakes out, it’s a big moment for the XENON1T collaboration, which involves more than 160 scientists from 28 institutions in 11 countries. Six university research groups are based in the United States, including one at the University of Chicago, home to the Kavli Institute for Cosmological Physics. KICP has helped support the involvement in XENON1T of Luca Grandi, Associate Professor of Physics at UChicago, and his graduate student Evan Shockley, one of the analysis leads behind the new results.

    “We have been very cautions and paranoid and have been sitting on this data for a very long period to try to find flukes in our analysis that could have artificially produced the bump,” says Luca Grandi, a member of KICP. “We hammered down all potential sources of systematic error that we could think of, but the excess turned out to be very solid and significant.”

    XENON1T accumulated 278 days of data during runs from October 2016 to February 2018.

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

    It represents the latest in an increasingly powerful line of experiments operated at the National Institute for Nuclear Physics’ Laboratori Nazionali del Gran Sasso, located in central Italy.

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

    Shielded under 1400 meters of mountain rock to avoid contamination from cosmic rays raining down from space, the facility is a premier location for highly sensitive traps for elusive particles.

    The XENON1T experiment itself consists of a giant tank filled with 3.2 tonnes of the element xenon, kept super-chilled in a liquid form at nearly -100 degrees Celsius. The xenon is ultra-purified to be free of radioactive elements, whose decay would trigger the instrument’s sensors. When particles do enter XENON1T and undergo rare interactions with its xenon dragnet, the interaction produces tiny light signals that researchers analyze. In most cases, the blips are attributable to expected, ho-hum sources—a so-called background. Finding any excess, then, above and beyond this deeply studied background is grounds for excitement.

    The best bet for the newly announced excess, in terms of matching observed signal to theoretical predictions, is an extremely lightweight particle called an axion. These particles were put forth in the late 1970s to work out a kink in the strong force, which holds matter together at the subatomic level and is one of the four fundamental forces of nature. If the Sun does produce XENON1T-detectable versions of these particles, that would boost the case for axions having been produced during the Big Bang 13.8 billion years ago. Such primordial axions should have been cranked out in mind-bogglingly prodigious amounts—enough, in fact, to constitute the universe’s long-sought dark matter. So while the recently observed excess is not dark matter proper, it could point the way toward at last tracking down the mysterious substance.

    The other compelling candidate for the excess is neutrinos (also produced by the Sun) possessing a larger-than-expected, so-called magnetic moment. All particles have this property, though just what it is for neutrinos has yet to be pinned down (as with so much else involving these enigmatic motes of matter). Neutrinos are already the bad boys and girls in the Standard Model, the encompassing framework for particle physics and three out of nature’s four fundamental forces. Discovering an anomalous magnetic moment for the particles would only further blaze trails into new physics.

    Standard Model of Particle Physics, Quantum Diaries

    “If the excess had to come from solar axions or neutrino anomalous magnetic moment, then this would have big implication on our present understanding of particle physics,” says Grandi.

    The least heart-stopping candidate for the excess, tritium, would still be important to firmly nail down in order to advance the search for dark matter and other novel particles. The tritium background contamination within XENON1T required to yield the excess would be infinitesimal—just a single tritium atom for every 10^25 xenon atoms. (10^25 is 10 septillion, but you already knew that, of course).

    “The detector is sensitive enough to see this excess, but not enough to discriminate among the few potential sources that we have considered and that might cause it, some including exciting new physics and some foreseeing the existence of a new type of background that was not accounted for before,” says Grandi. “When you push your technology to the edge to be sensitive to these elusive particles, you sometimes bump into unexpected background sources that nobody had thought about before.”

    The jury likely won’t remain out long, thanks to the next generation of the XENON1T experiment, dubbed XENONnT.

    XENONnT experiment at the Laboratori Nazionali del Gran Sasso (LNGS) underground laboratory in Italy.

    The upgrade will deliver a xenon mass that is three times larger than XENON1T’s and have even more precise components, lowering the background still further, thus increasing events while honing their possible origins. Major progress took place with readying XENONnT earlier this year before the novel coronavirus pandemic brought much of the world to a standstill, and at present, the next-gen detector’s start-up is anticipated in late 2020.

    “Given our estimates, we expect that XENONnT will be able to distinguish among the various hypotheses in a few months of data taking,” Grandi added in a statement. “This makes even more worth the big effort made, early in the year, to seal the new detector before the lockdown kicked in.”

    ___________________________________________________

    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, did most of the work on Dark Matter.

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

    Coma cluster via NASA/ESA Hubble

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

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

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

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


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


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

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

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

    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 Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

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

     
  • richardmitnick 1:12 pm on June 19, 2020 Permalink | Reply
    Tags: "ATLAS Experiment measures light scattering on light and constrains axion-like particles", , Axions, , , , , , ,   

    From CERN ATLAS via phys.org: “ATLAS Experiment measures light scattering on light and constrains axion-like particles” 

    CERN/ATLAS detector

    CERN ATLAS Higgs Event

    CERN ATLAS another view Image Claudia Marcelloni ATLAS CERN


    From CERN ATLAS

    via


    phys.org

    June 19, 2020

    1
    Figure 1: Differential cross section of γγ→γγ production in lead–lead collisions at 5.02 TeV as a function of the invariant mass of the diphoton system and the cosine of the scattering angle in the photon-photon centre-of-mass frame, as measured by ATLAS. The measurements are compared to the theoretical prediction. Credit: ATLAS Collaboration/CERN.

    Light-by-light scattering is a rare phenomenon in which two photons—particles of light—interact, producing another pair of photons. Direct observation of this process at high energy had proven elusive for decades, until it was first seen by the ATLAS Experiment in 2016 and established in 2019. In a new measurement, ATLAS physicists are using light-by-light scattering to search for a hyped phenomenon beyond the Standard Model of particle physics: axion-like particles.

    Collisions of heavy lead ions in the Large Hadron Collider (LHC) provide the ideal environment to study light-by-light scattering. As bunches of lead ions are accelerated, an enormous flux of surrounding photons is generated corresponding to an electrical field with strength of up to 1025 volt per metre. When ions from opposite beams pass next to each other at the centre of the ATLAS detector, their surrounding photons can interact and scatter off one another. Because the lead ions lose only a tiny fraction of their energy in this process, the outgoing ions continue their path around the LHC ring, unseen by the ATLAS detector. These interactions are known as ultra-peripheral collisions. This leads to a distinct event signature, very unlike typical lead ion collision events, with two back-to-back photons and no further activity in the detector.

    Based on lead-lead collision data recorded in 2015, the ATLAS Collaboration found the first direct evidence of high-energy light-by-light scattering. More recently the ATLAS Collaboration reported the observation of light-by-light scattering with a significance of 8.2 standard deviations, using a large data sample taken in 2018.

    2
    Figure 2: Compilation of exclusion limits at 95% confidence level in the photon–a (axion-like particle) coupling (1/Λa) versus a mass (ma) plane obtained by different experiments. The existing limits are compared to the limits extracted from this measurement. Credit: ATLAS Collaboration/CERN

    The ATLAS Collaboration has studied the full LHC Run-2 dataset of heavy-ion collisions to measure light-by-light scattering with improved precision and more detail. Out of the more than hundred billion ultra-peripheral collisions probed, ATLAS observed a total of 97 candidate events while 27 events are expected from background processes. In addition to the production rate (cross section), ATLAS measured the energies and angular distributions of the produced photons (i.e. their kinematics). The result explores a broader range of diphoton masses, increasing the expected signal yield by about 50% in comparison to the previous ATLAS measurements.

    The measurement of light-by-light scattering is sensitive to processes beyond the Standard Model, such as axion-like particles. These are hypothetical spin-less (scalar) particles with an odd parity quantum number (the Higgs boson, for example, is a scalar with even parity) and typically weak interactions with Standard Model particles. In the new ATLAS result, physicists considered whether the pairs of interacting photons produce axion-like particles (a) as they scatter off each other (γγ → a → γγ), which would lead to an excess of scattering events with diphoton mass equal to the mass of a. They examined the diphoton mass distribution for a mass range for a between 6 and 100 GeV. No significant excess of events over the expected background was found in the analysis. ATLAS physicists were able to derive, at a 95% confidence level, an exclusion bound of the axion-like particles coupling to photons (Figure 2). Assuming 100% of the putative particles decay to photons, this new analysis places the strongest existing limits on the production of axion-like particles in the examined mass range to date.

    With the much larger dataset expected in the future LHC runs, physicists will continue to explore the sensitivity of light-by-light scattering to phenomena beyond the Standard Model.

    More information: Measurement of light-by-light scattering and search for axion-like particles with 2.2 nb−1 of Pb+Pb data with the ATLAS detector (ATLAS-CONF-2020-010):
    https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2020-010/

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    CERN Courier

    Quantum Diaries
    QuantumDiaries

    CERN map


    CERN LHC Grand Tunnel
    CERN LHC particles

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: