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  • richardmitnick 11:37 am on October 4, 2022 Permalink | Reply
    Tags: "15 spectacular photos from the Dark Energy Camera", , , , , , Symmetry,   

    From “Symmetry”: “15 spectacular photos from the Dark Energy Camera” Photo Essay 

    Symmetry Mag

    From “Symmetry”

    10.4.22
    Lauren Biron

    ___________________________________________________________________
    The Dark Energy Survey

    Dark Energy Camera [DECam] built at The DOE’s Fermi National Accelerator Laboratory.

    NOIRLab National Optical Astronomy Observatory Cerro Tololo Inter-American Observatory (CL) Victor M Blanco 4m Telescope which houses the Dark-Energy-Camera – DECam at Cerro Tololo, Chile at an altitude of 7200 feet.

    NOIRLabNSF NOIRLab NOAO Cerro Tololo Inter-American Observatory(CL) approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

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

    According to Albert Einstein’s Theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up.

    _______________________________________________________________________
    Nobel Prize in Physics for 2011 Expansion of the Universe

    4 October 2011

    The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011

    with one half to

    Saul Perlmutter
    The Supernova Cosmology Project
    The DOE’s Lawrence Berkeley National Laboratory and The University of California-Berkeley,

    and the other half jointly to

    Brian P. SchmidtThe High-z Supernova Search Team, The Australian National University, Weston Creek, Australia.

    and

    Adam G. Riess

    The High-z Supernova Search Team,The Johns Hopkins University and The Space Telescope Science Institute, Baltimore, MD.

    Written in the stars

    “Some say the world will end in fire, some say in ice…” *

    What will be the final destiny of the Universe? Probably it will end in ice, if we are to believe this year’s Nobel Laureates in Physics. They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever-accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.

    In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.

    The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

    The teams used a particular kind of supernova, called Type 1a supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.

    For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.

    The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.

    *Robert Frost, Fire and Ice, 1920
    ______________________________________________________________________________

    To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called Dark Energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

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

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

    3
    Photo by Reidar Hahn, Fermilab.

    The powerful camera built for the Dark Energy Survey has taken more than 1 million photos from its perch in Chile. Here are some of the best.

    From high atop a mountain in the Chilean Andes, the Dark Energy Camera has snapped more than one million exposures of the southern sky. The images have captured around 2.5 billion astronomical objects, including galaxies and galaxy clusters, stars, comets, asteroids, dwarf planets, and supernovae.

    Now 10 years since the Dark Energy Camera first saw stars, the impressive 570-megapixel camera was originally built at the U.S. Department of Energy’s Fermi National Accelerator Laboratory for the Dark Energy Survey. The international DES collaboration uses the deep-space data to investigate dark energy, a phenomenon that is accelerating the expansion of space.

    The Dark Energy Survey, whose scientists are now analyzing the data collected from 2013-2019, isn’t the only experiment to benefit from the powerful piece of equipment. Other research groups have also used the camera to conduct additional astronomical observations and surveys. Here are some of the many stellar photos created using the Dark Energy Camera.

    3
    Acknowledgment: M. Soraisam (University of Illinois). Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin CTIO/NOIRLab/DOE/NSF/AURA.

    The Southern Pinwheel Galaxy (also known as Messier 83 or NGC 5236) is about 15 million lightyears from Earth. It took DECam more than 11 hours of exposure time to capture this image. The camera is mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory, a program of NSF’s NOIRLab.

    4
    Acknowledgments: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA.

    The Dark Energy Survey imaged one-eighth of the sky, capturing light from galaxies up to 8 billion lightyears away. The survey repeatedly imaged 10 “deep fields” like the one shown here. By returning to certain sections of the sky, scientists are able to build up and collect different wavelengths of light to image incredibly distant galaxies and faint objects. These deep fields can be used to calibrate the rest of the DES data and to hunt for supernovae.

    5
    Marty Murphy, Nikolay Kuropatkin, Huan Lin and Brian Yanny, Dark Energy Survey.

    While the Dark Energy Survey typically looks at objects millions or billions of lightyears away, sometimes closer objects come into view. In 2014, the Dark Energy Survey spotted Comet Lovejoy traveling about 51 million miles from Earth. Each rectangle in the image represents one of the 62 CCDs that DECam uses, each one a sophisticated sensor designed to capture light from distant galaxies.

    6
    Dark Energy Survey.

    The spiral galaxy NGC 1566, sometimes called the Spanish Dancer, is about 69 million lightyears from Earth. Each photo from DECam is the result of choices made during image processing. The camera uses five filters that each record a different wavelength of light (between 400 and 1,080 nanometers) and can be combined to make color images.

    7
    W. Clarkson (UM-Dearborn)/CTIO/NOIRLab/DOE/NSF /AURA/STScI, C. Johnson (STScI), and M. Rich (UCLA)

    This DECam photo, taken looking toward the center of our Milky Way galaxy, covers an area roughly twice as wide as the full moon and contains more than 180,000 stars. You can also see a wider version encompassing more of the Milky Way’s bulge. While beautiful, the stars and dust of the Milky Way block out distant galaxies needed to study dark energy—so the Dark Energy Survey typically aims the telescope in the opposite direction, away from the plane of our galaxy.

    8
    Erin Sheldon, Dark Energy Survey.

    From our position on Earth, we see the spiral galaxy NGC 681 from the side (or edge-on). The galaxy, also known as the Little Sombrero Galaxy, is about 66.5 million lightyears away. To keep images of distant objects as sharp as possible, DECam uses a mechanism called a Hexapod, which uses six pneumatically driven pistons to align the camera’s many optical elements between exposures. In addition to the five light filters, DECam also has five optical lenses, the biggest of which is more than 3 feet wide and weighs 388 pounds.

    6
    Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin
    CTIO/NOIRLab/NSF/AURA/SMASH/D. Nidever (Montana State University)

    This image shows a wide-angle view of the Small Magellanic Cloud. The Large and Small Magellanic Clouds are dwarf satellite galaxies to the Milky Way, and their proximity makes them a valuable place to study star formation. The Dark Energy Camera captured deep looks at our galactic neighbors for the Survey of the Magellanic Stellar History, or SMASH.

    10
    Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), J. Miller (Gemini Observatory/NSF’s NOIRLab), M. Zamani and D. de Martin (NSF’s NOIRLab) Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA

    The large galaxy at the center of this image is NGC 1515, a spiral galaxy with several neighboring galaxies in the Dorado Group. When looking at the large-scale structure of the universe, astronomers find galaxies are not distributed randomly but instead cluster together, forming a sort of cosmic web. The Dark Energy Survey has made some of the most precise maps of the universe’s structure and its evolution over time.

    11
    Robert Gruendl, Dark Energy Survey

    NGC 288 is a globular cluster of stars located about 28,700 lightyears from Earth. These stars are bound together by gravity and are concentrated toward the center of the sphere. Globular clusters are an interesting way to study how stars and our own Milky Way evolved, though the Dark Energy Survey looks at distant galaxies and galaxy clusters to better understand dark energy.

    12
    PI: M. Soraisam (University of Illinois at Urbana-Champaign/NSF’s NOIRLab) Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) CTIO/NOIRLab/DOE/NSF/AURA

    This Dark Energy Camera image shows light from Centaurus A, a galaxy more than 12 million lightyears away. It is partially obscured by dark bands of dust caused by the collision of two galaxies.

    13
    Image processing: DES, Jen Miller (Gemini Observatory/NSF’s NOIRLab), Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin DES/DOE/Fermilab/NCSA and CTIO/NOIRLab/NSF/AURA

    The Dark Energy Survey has found several new dwarf galaxies and used the data to limit how big potential dark matter particles could be. This irregular dwarf galaxy, IC 1613, is about 2.4 million lightyears away and contains around 100 million stars. Dwarf galaxies are considered small and faint by astronomical standards; for comparison, our Milky Way galaxy is estimated to contain between 100 and 400 billion stars.

    14
    Rob Morgan, Dark Energy Survey

    The Helix Nebula (NGC 7293) is a planetary nebula about 650 lightyears from Earth. It is shown here extending over several of the Dark Energy Camera’s CCDs. Planetary nebulae, so named because they appeared round and sharp-edged like planets, are actually the remains of stars. Here, a dying star has ejected its outer layers, leaving a small white dwarf surrounded by gas. In billions of years, our own sun will experience a similar fate.

    15
    Dark Energy Survey

    The spiral Sculptor Galaxy is about 11 million lightyears away. It’s one of more than 500 million galaxies imaged by the Dark Energy Survey across 5000 square degrees of sky. To optimize observations, DES used automated software to point the camera and capture exposures. The software could factor in what part of the sky was overhead, weather conditions, moonlight, and which areas had been recently imaged.

    16
    Image processing: DES, Jen Miller (Gemini Observatory/NSF’s NOIRLab), Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin DES/DOE/Fermilab/NCSA and CTIO/NOIRLab/NSF/AURA

    The wispy shells around elliptical galaxy NGC 474 (center) are actually hundreds of millions of stars. To the left is a spiral galaxy, and in the background there are thousands of other, more distant galaxies—visible in this zoomable version. DECam images contain vast amounts of information; each one is about a gigabyte in size. The Dark Energy Survey would take a few hundred images per session, producing up to 2.5 terabytes of data in a single night.

    17
    Dark Energy Survey

    The Dark Energy Camera captured the barred spiral galaxy NGC 1365 in its very first photographs in 2012. The galaxy sits in the Fornax cluster, about 60 million lightyears from Earth. This close-up comes from the camera’s much wider field of view, which you can explore in the interactive DECam viewer.

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:43 pm on September 20, 2022 Permalink | Reply
    Tags: "Catching neutrinos at the LHC", , , , , , , , Scattering and Neutrino Detector or SND@LHC, Symmetry   

    From “Symmetry”: “Catching neutrinos at the LHC” 

    Symmetry Mag

    From “Symmetry”

    9.20.22
    Chetna Krishna

    After the successful initiation of two new detectors, scientists have begun to envision an expanded suite of neutrino experiments at the Large Hadron Collider.

    CERN physicist Jamie Boyd enters a tunnel close to the ATLAS detector, an experiment at the largest particle accelerator in the world. From there, he turns into an underground space labeled TI12.

    “This is a very special tunnel,” Boyd says, “because this is where the old transfer line used to exist for the Large Electron-Positron Collider, before the Large Hadron Collider.” After the LHC was built, a new transfer line was added, “and this tunnel was then abandoned.”

    The tunnel is abandoned no more. Its new resident is an experiment much humbler in size than the neighboring ATLAS detector. Five meters in length, the ForwArd Search ExpeRiment, or FASER, detector sits in a shallow excavated trench in the floor, surrounded by low railings and cables.

    Scientists—including Boyd, who serves as co-spokesperson for FASER—installed the relatively small detector in 2021. Just in time before restarting the LHC in April, physicists nestled another small experiment, called Scattering and Neutrino Detector or SND@LHC, on the other side of ATLAS.

    2
    The SND@LHC experiment consists of an emulsion/tungsten target for neutrinos (yellow) interleaved with electronic tracking devices (grey), followed downstream by a detector (brown) to identify muons and measure the energy of the neutrinos. (Image: Antonio Crupano/SND@LHC)

    Both of the detectors are now running and have started collecting data. Scientists say they hope the two detectors represent the beginning of a new effort to catch and study particles that the LHC’s four main detectors can’t see.

    Hiding in plain sight

    Both FASER and SND@LHC detect particles called neutrinos. Not to be confused with neutrons—particles in the nuclei of atoms that are made up of quarks—neutrinos cannot be broken down into smaller constituents. Along with quarks, electrons, muons and taus, neutrinos are fundamental particles of matter in the Standard Model of physics.

    These light, neutral particles are abundant across the galaxy. Some have been around since the Big Bang; others are produced in particle collisions, such as those that happen when cosmic rays strike the atoms that make up Earth’s atmosphere. Every second, neutrinos pass through us in the trillions without leaving a trace—because they only rarely interact with other matter.

    Neutrinos are also produced in collisions at the LHC. Scientists are aware of their presence, but for more than a decade of LHC physics, neutrinos went undetected, as the ATLAS, CMS, LHCb and ALICE detectors were designed with other types of particles in mind.

    The four biggest LHC experiments cannot detect neutrinos directly, says Milind Diwan, a senior scientist at the US Department of Energy’s Brookhaven National Laboratory. Diwan was an original proponent of and spokesperson for what is now the Deep Underground Neutrino Experiment hosted by The DOE’s Fermi National Accelerator Laboratory.

    In 2021, FASER became the first detector to catch neutrinos at the LHC—or any particle collider.

    A new way of looking at neutrinos

    Neutrinos are the chameleons of the particle world. They come in three flavors, called muon, electron and tau neutrinos [above] for the particles associated with them. As they travel through the universe at nearly the speed of light, neutrinos shift between the three flavors. Both FASER and SND@LHC can detect all three flavors of neutrinos.

    The detectors will catch only a small fraction of the neutrinos that pass through them, but the high-energy collisions of the LHC should produce a staggering number of the particles. For example, during the current run of the LHC, which will last until the end of 2025, physicists estimate FASER and its new subdetector, called FASERv (pronounced FASERnu), will experience a flux of 200 billion electron neutrinos, 6 trillion muon neutrinos, and 4 billion tau neutrinos, along with a comparable number of anti-neutrinos of each flavor.

    “We are now guaranteed to see thousands of neutrinos at the LHC for the first time,” says Jonathan Feng, co-spokesperson for the FASER collaboration.

    Those neutrinos will be at the highest energies ever seen from a human-made source, says Tomoko Ariga, project leader for FASERv, who previously worked on the DONUT neutrino experiment. “At such extreme energies, FASERv will be able to probe neutrino properties in new ways.”

    The experiments will provide a new way of studying other particles as well, says Giovanni De Lellis, spokesperson for both SND@LHC and the OPERA neutrino experiment.

    Because a large fraction of the neutrinos produced in the range accessible to SND@LHC will come from the decays of particles made of charm quarks, SND@LHC can be used to study charm-quark particle production in a region that other LHC experiments cannot explore. This will help both physicists studying collisions at future colliders and physicists studying neutrinos from astrophysical sources.

    FASER and SND@LHC could also be used to detect dark matter, Diwan says. If dark-matter particles are produced in collisions at the LHC, they could slip away from the ATLAS detector alongside the beamline—right into FASER and SND@LHC.

    A proposal for the future

    These experiments could be just the beginning. Physicists have proposed five more experiments—including advanced versions of the FASER and SND@LHC detectors—to be built near the ATLAS detector. The experiments—FASERv2, Advanced SND, FASER2, FORMOSA and FLArE—could sit at a proposed Forward Physics Facility during the next phase of the LHC, the High-Luminosity LHC.

    The advanced FASERv and SND@LHC detectors would boost the experiments’ detection of neutrinos by a factor of 100, Feng says. “This means, for example, that instead of tens of tau neutrinos, they will detect thousands, allowing us to separate tau neutrinos from anti-tau neutrinos and do precision studies of these two independently for the first time.”

    The FLArE experiment, which would detect neutrinos in a different way from FASER and SND@LHC, could also be sensitive to light dark matter.

    Even without the proposed future experiments, scientists are poised to learn more about neutrinos from their studies at the LHC. FASERv and SND@LHC have already began taking physics data and are expected to present new results in 2023.

    “Neutrinos are amazing,” Feng says. “Every time we look at them from a new source, whether it is a nuclear reactor or the sun or the atmosphere, we learn something new. I am looking forward to seeing what surprises nature has in store.”

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:05 am on September 6, 2022 Permalink | Reply
    Tags: "Majorana Demonstrator finds ‘tantalizing’ new purpose", , , , Scientists are using a detector originally designed to study neutrinos to pin down an elusive nuclear physics measurement., Symmetry, The study of tantalum-180m - new research effort   

    From “Symmetry”: “Majorana Demonstrator finds ‘tantalizing’ new purpose” 

    Symmetry Mag

    From “Symmetry”

    9.6.22
    Erin Lorraine Broberg|SURF

    Scientists are using a detector originally designed to study neutrinos to pin down an elusive nuclear physics measurement.

    In Greek mythology, the Olympic gods punished the demigod Tantalus by chaining him in a pool of water beneath a tree heavy-laden with fruit. If Tantalus reached toward the fruit to satisfy his hunger, the branches recoiled. If he stooped to slake his thirst, the water receded.

    The story of this perpetual punishment is the origin of both the verb “to tantalize” and the related word “tantalum.” Tantalum is a rare element formed in the heart of dying stars, named for its inability to absorb acid, even when immersed in a pool of it.

    Much like the water and fruit that evaded Tantalus, a complete understanding of an isotope of tantalum has evaded scientists. “Probably every nuclear physicist has heard of this problem; it’s an open, standing question,” says Samuel Meijer, a staff scientist at the US Department of Energy’s Los Alamos National Laboratory.

    But the tantalum question may soon have an answer, thanks to a detector originally designed to study neutrinos.

    Up in the air

    In the nuclear world, particles are constantly seeking equilibrium.

    When a proton or neutron in the center of an atom receives a burst of energy, it leaps to a higher, unstable energy level, like a child receiving a push on a playground swing. To regain stasis, the proton or neutron decays, falling back like the swing swaying back to its lower energy level.

    This usually happens right away. But sometimes, says Ralph Massarczyk, also a staff scientist at The DOE’s Los Alamos National Laboratory, the proton or neutron gets stuck.

    A “stuck” particle—our child on a swing, now mysteriously suspended mid-air—is ruled by a strange law of physics called “spin-suppression.”

    It might take several seconds for the stuck particle to decay back to its ground state. It might take years.

    These stuck particles, called metastable isomers, do eventually come unstuck again. Scientists know this because they have seen almost every one of them do it—except one.

    “Tantalum-180m is the only unobserved metastable state decay,” Meijer says.

    Theory predicts that the half-life of tantalum-180m, one of tantalum’s two natural states, should be between 10^17 and 10^18 years. That’s far longer than the universe itself has existed.

    Some tantalum-180m atoms will decay more quickly than others. Scientists can increase their chances of witnessing a decay by increasing the number of atoms they monitor and by decreasing backgrounds. Still, the longer the lifetime, the more difficult catching the decay becomes.

    Tantalum is among the rarest elements in the solar system, and the tantalum-180m isotope makes up only 0.012% of naturally occurring tantalum.

    The telltale sign of tantalum-180m’s decay is the release of a gamma ray. In an ultra-sensitive detector, even small amounts of background radiation from the sun, the atmosphere and dust can crowd that signal out.

    In 2016, researchers in the HADES underground laboratory in Belgium placed 1.5 kilograms of tantalum (containing about 180 milligrams of tantalum-180m) between two high-purity germanium detectors in the hopes of observing a decay.

    3
    The HADES underground research laboratory | Euridice

    The collaboration watched and waited 244 days for a signal that never came. The HADES experiment set the most stringent lower limit on the lifetime of tantalum-180m: 4.5×10^16 years.

    Under the ground

    A new effort to observe the decay of tantalum-180m is underway, at a detector originally constructed to observe an even rarer process.

    The Majorana Demonstrator [above] was built to test technology for the search for neutrinoless double-beta decay—a theoretical process that releases two neutrinos, which crash into one another and mutually destruct.

    Observing neutrinoless double-beta decay would answer an important question physicists have about neutrinos: Are they their own antiparticles? If they can annihilate one another, they must be.

    The Majorana Demonstrator collaboration built their detector with ultra-pure materials, then placed it within layers of shielding in a cleanroom 4,850 feet underground at Sanford Underground Research Facility in South Dakota. There, nearly a mile of rock shields the experiment from backgrounds created by cosmic rays and the sun.

    After six years of operation, the Majorana Demonstrator scientists proved their technology and paved the way for a next-generation experiment. As the experiment run drew to a close, collaboration members Massarczyk and Meijer proposed that the detector and lab space be repurposed to study tantalum-180m.

    The quest to observe the last remaining decay of a metastable isomer “fits with what we, the Majorana Demonstrator collaboration, do,” says Vincente Guiseppe, co-spokesperson of the Majorana Collaboration and a research staff member at The DOE’s Oak Ridge National Laboratory. “Our primary goal is to look for a decay that has never been observed, so adapting the Majorana Demonstrator to search for the decay of tantalum-180m makes perfect sense.”

    Massarczyk and Meijer took on the task in April, becoming primary investigators—PI and co-PI, respectively—for the new experiment. They placed 17.4 kilograms of tantalum (containing about 2.088 grams of tantalum-180m) inside the Majorana Demonstrator detector.

    With the support of The DOE’s Los Alamos National Laboratory Lab-Directed Research and Development program, Massarczyk says, the scientists were able to create the new experiment with minimal effort and minimal cost.

    The Majorana Demonstrator will build on the HADES collaboration’s already impressive result.

    “Compared to the HADES experiment, we have more than 10 times the tantalum mass,” Meijer says. “We also have an array of 23 detectors, compared to the 2 detectors used previously. This gives us a higher measurement efficiency, and we are more likely to see the signature gamma rays that come off the tantalum-180m.”

    A win-win situation

    By monitoring this large sample of tantalum-180m for a full year, the experiment will measure the half-life of tantalum-180m to 1019 years, an order of magnitude beyond its predicted half-life.

    “It is difficult to measure a handful of atoms for 1019 years, so instead, we might watch 1019 atoms for a handful of years and count up how many decays we see,” says Meijer. “Because determining the half-life of an isotope is a statistical process, you want to see as many decays as possible to estimate the half-life with greater precision. Increasing both the number of atoms and the measurement time improves the number of signals you might see.”

    If the prediction is correct, the experiment will finally witness a decay of tantalum-180m.

    If tantalum-180m is observed to decay, it could encourage researchers to look closer for the influence of theoretical dark-matter particles. Scientists think that dark-matter particles could “push” the protons or neutrons in tantalum-180m to decay.

    But the scientists could also find that the theoretical prediction is wrong.

    “If the prediction is wrong, that’s still exciting, because it points us in a new direction,” Meijer says. “In some sense, you can’t really lose by trying to make this measurement with this setup. We know that we will measure something interesting, regardless of what happens.”

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 9:42 am on August 23, 2022 Permalink | Reply
    Tags: "Accelerator operators:: pillars of particle physics", , , , , , It takes years of on-the-job training to learn the ins and outs of particle accelerator operation., , , , Symmetry   

    From “Symmetry”: “Accelerator operators:: pillars of particle physics” 

    Symmetry Mag

    From “Symmetry”

    8.23.22
    Emily Driehaus

    It takes years of on-the-job training to learn the ins and outs of particle accelerator operation.

    Despite the fact that accelerator operators are essential to keeping an accelerator laboratory afloat, the role is largely unknown outside of physics—even to the people who wind up in the job.

    “It was a kind of position that I wasn’t familiar with or knew even existed before,” says Judah O’Neil, who for the last two years has worked at the US Department of Energy’s Fermi National Accelerator Laboratory.

    At Fermilab, accelerator operators are responsible for maintaining and running the machinery needed to provide beams of particles to all the experiments around the lab.

    It all starts with the 500-foot linear accelerator, or Linac, which operators use to give a beam of protons their first kick. From the Linac, the proton beam heads to the Booster, a 1,500-foot circular accelerator that increases the energy of the beam. From there, operators can direct the beam to different parts of the complex, including Fermilab’s neutrino and muon experiments.

    By steering protons from the Booster into a target, operators can create beams of low-energy neutrinos for neutrino experiments. Operators can also transfer a beam from the Booster into the 2-miles-in-circumference Recycler instead to change its composition or produce beams of muons for muon experiments. Transferring protons from the Recycler to the Main Injector, the next step along the line, allows operators to ramp up the energy even more. They use the Main Injector, also 2 miles in circumference, to produce the world’s highest-intensity neutrino beam for long-baseline neutrino experiments.

    The PIP-II construction project, currently underway, will increase the capabilities of the entire accelerator complex with a brand-new 700-foot linear superconducting accelerator.

    All of this, along with maintenance of the separate parts of the accelerator complex, goes through the accelerator operators in Fermilab’s Main Control Room.

    Each group of operators, led by a crew chief, rotates through day, evening and overnight shifts to keep the control room staffed 24/7. “[Having rotating shifts] allows you to know everyone and get experience at different times during the day,” O’Neil says. “You get to be in the control room and talk to the experts, see what’s going on, and meet everyone.”

    Working in the control room requires operators to multitask. They must keep track of multiple monitors at their individual consoles, along with bigger screens that display to the whole room an overall system status and a weather radar—since the accelerator complex can be affected by storms. Beeps and blips and other sound effects provide auditory cues that can cut through the noise of people coming in to check out access keys, inform operators of an issue, or just pop by for a quick hello. If something goes wrong, operators are the ones to head out to investigate and either solve the problem or find a more senior operator who can.

    Operators don’t learn how to manage these responsibilities overnight. They go through a training period that lasts through their first two years on the job.

    “You aren’t even assigned to a crew for your first month because you’re just getting through some initial training,” says Laura Bolt, who has been an operator since November 2021. “For the first year to two years that you’re here, your primary objective is to finish that training and also be helpful in the control room.”

    Once operators complete their on-the-job training, or OJTs, they can then either specialize in a specific area or help train newer operators.

    “When you start, you are doing things, but it’s usually with supervision or you’re watching somebody do something so you learn how to do it,” says Cassidy Mayorga, who has been an operator for four years. “Then you slowly shift into doing it on your own, and then you shift into doing it to teach other people.”

    Mayorga serves on the training committee and helps make sure training documentation is up-to-date.

    Completing OJTs involves studying instruction manuals and taking written tests, supplemented by in-person instruction from senior operators.

    Because so much of an operator’s training comes from collaboration and getting hands-on experience with supervision, the pandemic had a significant impact on the Main Control Room at Fermilab. The usual hustle and bustle came grinding to a halt as operators acclimated to new schedules and skeleton crew shifts to allow for social distancing. “It was a big adjustment,” Mayorga says. “It was very quiet and kind of unnerving.”

    For operators who were hired during the pandemic, the gradual lifting of restrictions and more recent return to semi-normal daily operations gave them a new appreciation for their colleagues’ expertise.

    “It’s really good to have those conversations with the experts and be able to have a lot of people in the control room at once because you get different opinions, you get to learn a lot of things,” O’Neil says.

    The operators are a diverse group. Some of them have known that they wanted to work at Fermilab since they were young, others stumbled across the position just by chance. There are writers, like Bolt; amateur astronomers, like O’Neil; and Ultimate Frisbee enthusiasts, like Mayorga. Many share at least one interest: video games.

    Bolt, O’Neil and Mayorga all say that being an operator is a great gig for those interested in the hands-on elements of particle physics, including those who don’t plan to follow the usual path straight through a physics PhD. “The cool factor of this job is just off the charts,” Bolt says. “This is the perfect place for non-traditional physics students.”

    ___________________________________________________________________
    LHC

    LHC

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    ALICE

    CMS

    LHCb


    ___________________________________________________________________

    [Earlier than the LHC at CERN, The DOE’s Fermi National Accelerator Laboratory had sought the Higgs with the Tevatron Accelerator.

    But the Tevatron could barely muster 2 TeV [Terraelecton volts], not enough energy to find the Higgs. CERN’s LHC is capable of 13 TeV.

    Another possible attempt in the U.S. would have been the Super Conducting Supercollider.

    Fermilab has gone on to become a world powerhouse in neutrino research with the LBNF/DUNE project which will send neutrinos 800 miles to SURF-The Sanford Underground Research Facility in in Lead, South Dakota.]
    __________________________________________________________

    See the full article here .


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  • richardmitnick 8:25 pm on August 9, 2022 Permalink | Reply
    Tags: "Four (more) things you might not know about antimatter", All atoms contain antimatter., Antimatter is around you - it’s a part of you - and scientists are still trying to figure it out., Antimatter was originally predicted through math., “Positrons”: the first confirmed observation of antimatter-predicted in 1928 by Paul Dirac- Photographed 2 August 1932 by Carl D. Anderson., , , , Scientists are currently searching for other particles: axions; supersymmetric particles; dark matter particles., Scientists are probing exotic atoms to search for signs of an unusual “fifth force” between the antiproton and the electron., Scientists can create hybrid atoms made partially out of antimatter., Scientists have found more antimatter in our galaxy than they can currently explain., Symmetry, The antimatter versions of protons—antiprotons—contain three unpaired antiquarks.   

    From “Symmetry”: “Four (more) things you might not know about antimatter” 

    Symmetry Mag

    From “Symmetry”

    8.9.22
    Diana Kwon

    Antimatter is around you – it’s a part of you – and scientists are still trying to figure it out.

    Antimatter: It’s the opposite of the matter we’re used to; it’s mysteriously elusive; and when it gets too close to ordinary matter, the two annihilate on contact.

    But there’s even more to the extraordinary stuff, including these four fascinating facts.

    All atoms contain antimatter.

    The first three subatomic particles you ever learned about were likely the proton, neutron and electron. These particles make up the atoms that form our bodies and the world around us.

    Of the group, only the electron is elementary, which means it is not made up of any smaller components. Protons and neutrons, on the other hand, are each made up of elementary particles called quarks and gluons.

    Protons and neutrons are usually described as being composed of three quarks. But the reality is much messier than that. Protons and neutrons contain whole seas of quarks, antiquarks and gluons. Inside a proton or a neutron, particles and antiparticles constantly collide and annihilate one another.

    Protons and neutrons are described as being made up of just three quarks because, within this maelstrom of appearing and disappearing particles, three quarks remain without an antimatter counterpart, says Beatriz Gato-Rivera, a researcher at the Spanish National Research Council and author of a book about antimatter. The antimatter versions of protons—antiprotons—contain three unpaired antiquarks instead.

    Antimatter is all around you, inside every one of your atoms, along with the atoms of everything around you.

    Antimatter was originally predicted through math.

    In 1928, British physicist Paul Dirac was faced with a puzzle. To describe the behavior of electrons, he had formulated a theory that combined Albert Einstein’s Theory of Special Relativity and Quantum Mechanics. But for his mathematical equations to work, he needed a particle that, at least at the time, wasn’t known to exist. The new particle needed to have the same mass as an electron but the opposite charge.

    Three years later, he finally proposed the existence of such a particle, which he called an “anti-electron.”

    That same year, the American physicist Carl Anderson, at the California Institute of Technology, was taking pictures of strange particle tracks left by cosmic rays traversing a particle detector known as a cloud chamber.

    1
    Cloud chamber photograph of the first positron ever observed. The thick horizontal line is a lead plate. The positron entered the cloud chamber in the lower left, was slowed down by the lead plane, and curved to the upper left. The curvature of the path is caused by an applied magnetic field that acts perpendicular to the image plane. The higher energy of the entering positron resulted in lower curvature of its path.
    A 63 million volt positron (Hρ = 2.1×105 gauss-cm) passing through a 6 mm lead plate and emerging as a 23 million volt positron (Hρ = 7.5×104 gauss-cm). The length of this latter path is at least ten times greater than the possible length of a proton path of this curvature.
    Date Photographed 2 August 1932. Published 15 March 1933.
    Source Anderson, Carl D. (1933). “The Positive Electron”. Physical Review 43 (6): 491–494. Physical Review Journals Archive [below].
    Author Carl D. Anderson (1905–1991)

    In 1932, Anderson confirmed that the tracks came from the particles Dirac had predicted, produced when cosmic rays collided with Earth’s atmosphere. Anderson dubbed the particles “positrons.” This was the first confirmed observation of antimatter.

    Unbalanced mathematical equations have led to the prediction of other particles as well. During the early 20th century, the masses and stability of atoms could not be explained by their protons and electrons alone. Ernest Rutherford proposed that another, neutral particle must be adding to their weight—the neutron. And in 1930, scientists needed something to explain why nuclei that emitted energy in the form of beta particles during radioactive decay didn’t recoil straight back, but at an angle. Wolfgang Pauli proposed that the decay must be emitting another, invisible particle at the same time—a particle later named the neutrino.

    Scientists are currently searching for other particles: axions; supersymmetric particles; dark matter particles, that could explain many longstanding puzzles in particle physics and cosmology.

    Scientists can create hybrid atoms made partially out of antimatter.

    By slowing antiprotons in a particle decelerator and then combining them with cryogenic helium, scientists can produce a metastable hybrid atom called anti-protonic helium.

    Hybrid atoms like this are called “exotic” atoms. Generally speaking, an exotic atom has a constituent particle swapped out for another particle with the same charge. In some cases, the new particle is a form of antimatter. In anti-protonic helium, a helium atom’s electron is replaced with an antiproton. Other examples include muonium (which contains an antimuon and an electron) and positronium (which contains an electron and a positron).

    Exotic atoms are used to study interactions between matter and antimatter on a minuscule scale. The short-scale interactions between the particles and antiparticles within atoms enable researchers to study phenomena that may not be investigated otherwise.

    “These short-scale interactions are an important tool in searching for new physics,” says Anna Soter, a particle physicist at ETH Zurich.

    Scientists are probing exotic atoms to search for signs of an unusual “fifth force” between the antiproton and the electron. Scientists also use exotic atoms to gather very precise measurements of particles’ properties. This enables them to test symmetries in the Standard Model, such as the prediction that particles and their antiparticles should have exactly the same mass and charge (although with the opposite sign).

    “To date, the metastable antiprotonic helium atom is the largest antimatter-containing exotic atom that scientists have been able to study using laser spectroscopy,” Soter says. “But simpler systems, like muonium and positronium, are also exciting to study. These atoms consist of only elementary particles, in the absence of strong interaction.”

    In addition to creating hybrid particles, scientists can also create anti-atoms. For example, by combining antiprotons and positrons, scientists at CERN are producing anti-hydrogen.

    Scientists have found more antimatter in our galaxy than they can currently explain.

    In the 1970s, the European Space Agency’s INTEGRAL mission detected a gamma ray signal in the center of the Milky Way.

    The brightness and distribution of this signal indicated that the equivalent of 9 trillion kilograms of positrons (that’s 1043 positrons) within our galaxy’s core were being annihilated each second—much more than scientists expected.

    Where all these positrons come from is an open question. Some candidates include the supermassive black hole at the center of the galaxy, other massive black holes in the vicinity, rapidly spinning neutron stars called pulsars, and annihilations between dark matter particles.

    Several experiments aim to locate the source of the gamma-rays in the center of our galaxy. The Compton Spectrometer and Imager (COSI), for example, is a gamma-ray telescope that will image our galaxy’s core to probe for the source of these positrons.

    Other efforts, such as the proposed All-sky Medium Energy Gamma-ray Observatory (AMEGO), also aim to shed light on this mystery.

    More recently, scientists detected a second excess of positrons, this one at much higher energy. The cosmic-ray detector PAMELA, on board a Russian satellite, discovered in 2008 that more antimatter particles were traveling past Earth than scientists had originally predicted. Other experiments, such as AMS-02, installed on the International Space Station in 2011, have confirmed the PAMELA collaboration’s finding.

    Where do these extra positrons come from? Several hypotheses have been put forward. According to Tim Linden, an astronomer at Stockholm University, the strongest contenders may be pulsars.

    Scientists have been studying gamma rays from pulsars to figure out how many positrons the stars release. “We’re getting numbers that match very well with models where pulsars would produce the excess positrons that we see,” Linden says.

    For more antimatter facts, see Ten things you might not know about antimatter.

    Science paper:
    Physical Review Journals Archive

    See the full article here .


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  • richardmitnick 2:09 pm on August 4, 2022 Permalink | Reply
    Tags: "Why aren’t neutrinos adding up?", , , , Physicists take on the mystery of the missing (and extra) neutrinos., , Symmetry   

    From “Symmetry”: “Why aren’t neutrinos adding up?” 

    Symmetry Mag

    From “Symmetry”

    8.4.22
    Mara Johnson-Groh

    Physicists take on the mystery of the missing (and extra) neutrinos.

    Of all the known elementary particles, neutrinos probably give physicists the most headaches.

    These tiny fundamental bits of matter are the second most common particle in the universe yet are anything but ordinary. Since their discovery, they have taunted scientists with bizarre behaviors, some of which physicists have yet to comprehend.

    One source of confusion has showed up in the results from short-distance neutrino experiments, in which neutrinos are measured after traveling somewhere between a few meters and a kilometer. When scientists measure neutrinos in these experiments, the results don’t always match their predictions. Sometimes there are too many of certain types of neutrinos, while in others there are too few.

    This mismatch between experiments and predictions has opened a whole subfield in the study of neutrinos since it was first identified in the early 2000s.

    While the answer to the mystery could provide physicists with a better understanding of neutrinos, it might also reveal new insights into the fundamental workings of the universe.

    Short-baseline anomalies

    At the heart of the short-distance miscounts are so-called short-baseline neutrino experiments.

    Such experiments typically have a well-understood source or a beam of neutrinos in one location and, some distance away, a detector that can identify one or more of the three different known types of neutrinos—electron neutrino, muon neutrino, and tau neutrino. These experiments look to see if what interacts with the detector is what scientists expect, based on what they know about the neutrinos coming from the source.

    This should be straightforward, but unlike most other particles, neutrinos are shape-shifters. Instead of being one thing their whole lives, neutrinos change their type—or “flavour,” as physicists say—as they travel. Similar to how photons travel as waves but interact as particles, each neutrino travels as a probabilistic mix of the three different flavours. Only when it interacts does it settle on a single one. Physicists call this “neutrino oscillation”.

    “A neutrino particle doesn’t just have one flavour, and the chance you’ll see it as a certain flavour comes down to probability,” says Zara Bagdasarian, an assistant project scientist at the University of California-Berzerkeley. “It is essentially a quantum phenomenon.”

    Of the three different neutrinos, each has a different probability of interacting as each of the three flavours. Additionally, each has a unique mass, so it travels at its own speed. In the end, this means each flavour has a greater likelihood of showing up at some distances than others. The theoretical framework that describes neutrino oscillations tells physicists how many neutrinos of each flavour should show up at different distances.

    Over long distances, neutrinos have sufficient time to change flavours—and this is well supported by experiments that study neutrinos traveling to Earth from the sun and experiments that analyze neutrino beams sent halfway across a continent. Over short distances, neutrinos don’t have as much time to oscillate and shift to a different flavour.

    But time after time in these short-baseline experiments, including experiments at beam lines and at nuclear reactors, predictions seem to be wrong. In some experiments, too many electron neutrinos appear, while in others, too few show up. These counting mismatches are called short-baseline anomalies.

    In the two decades since the anomalies were first discovered, scientists have come up with several guesses about what might cause discrepancies. To test the merits of these ideas, they are working on several ongoing and upcoming experiments.

    “At this point there’s a plethora of guesses,” says Georgia Karagiorgi, associate professor of physics at Columbia University. “However, there’s not a clear best guess because no single model can explain all anomalies simultaneously.”

    See the full article here .


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  • richardmitnick 2:05 pm on July 19, 2022 Permalink | Reply
    Tags: "LHCb ramps up the search for dark photons", , , , , , , , , , Symmetry   

    From “Symmetry”: “LHCb ramps up the search for dark photons” 

    Symmetry Mag

    From “Symmetry”

    07/19/22
    Katrina Miller

    A handful of physicists have prepared the LHCb detector for a more sophisticated dark matter search.

    1
    Illustration by Sandbox Studio, Chicago with Olena Shmahalo.

    Researching subatomic particles is an involved process. It can take hundreds—if not thousands—of scientists and engineers to build an experiment, keep it up and running, and analyze the enormous amounts of data it collects. That means physicists are always on the lookout for ways to do more for free: to squeeze out as much physics as possible with the machinery that already exists. And that’s exactly what a handful of physicists have set out to do with the LHCb experiment at CERN.

    The LHCb detector was originally designed to study a particle known as the beauty quark.

    “But as time has gone on, people have seen just how much more we can do with the detector,” says Daniel Johnson, an LHCb collaborator based at MIT.

    Johnson, along with a team of around 10 researchers from MIT, the University of Cincinnati and CERN, are leading LHCb’s search for dark matter, a hypothesized type of matter that, so far, has evaded detection.

    “Dark matter forms this big fraction of matter in the universe,” says Johnson, who won an Ernest Rutherford early career fellowship through the University of Birmingham, where he will move next March, to help spearhead the search. “It’s got to be there because of the way that galaxies dance, but we just don’t have a particle to explain it.”

    For decades, scientists have focused efforts on building increasingly larger experiments with improved sensitivity to observe a dark-matter particle interacting with the detector itself. These experiments are often tucked away deep underground to minimize other, more frequent, types of interactions that can mask potential dark-matter signals.

    But these direct detection searches have yet to find anything. “And that’s not to say that they’re a failure,” Johnson says. “They’ve been extremely successful so far at telling us what dark matter isn’t.”

    It is to say, however, that physicists may need to adopt more creative explanations as to what the elusive particle could be. One idea growing in popularity is that dark matter might not interact directly with ordinary matter at all. Instead, it might be part of a dark sector of particles and forces that exist completely separate from, but parallel to, those that make up the world we experience every day.

    Physicists are hopeful that they can access this dark sector through something called a portal, a rare hypothetical process that establishes a connection between ordinary and so-called dark particles. The LHCb team is particularly interested in portal interactions that convert a dark photon into a regular photon, which will then decay into charged particles that can be detected.

    Past efforts have ruled out the existence of dark photons with certain properties, but LHCb’s design puts it in a sweet spot to explore dark photons with masses and lifetimes that other experiments, so far, have not been sensitive to. Even better, observing these photons requires no upgrades to LHCb itself, says MIT graduate student Kate Richardson, who works closely with Johnson on the dark-photon search.

    That’s not to say scientists haven’t made improvements to the experiment. Richardson, in particular, has been involved in updating the LHCb’s software trigger, an algorithm that makes a snap decision about whether to store or discard any particle activity occurring inside the detector. “We can’t keep everything that happens,” she says.

    Though the experiment’s data storage rivals the size of Netflix servers, it holds only a small fraction of the data generated, Richardson says. “So we write code in the trigger to check if particles match certain requirements, like if they came from the same place and have a certain momentum, and keep those interactions to analyze later.”

    Previously, the team used LHCb’s dataset to conduct a preliminary dark-photon search that looked for regular photons decaying into muon-antimuon pairs. The software trigger upgrade paves the way for them to search for an additional type of interaction: regular photons that decay into electron-antielectron pairs, which could originate from dark photons with much lighter masses. This new search, which will take place alongside the primary physics analyses of the experiment, will be in the data-taking stage through the end of 2025.

    In the scenario that a dark-photon signal is found, further studies—both with the LHCb and other detectors—would need to confirm the result, since the search is the first of its kind to investigate dark photons at the masses and lifetimes that LHCb is sensitive to. In later runs, Richardson says, the software trigger could be reprogrammed to hone in on a more specific interaction signature, based on what mass and lifetime values seem promising after an analysis using the new data.

    Both Johnson and Richardson are excited about what information their future results will add to the 89-year-long quest to understand the nature of dark matter. “Someone’s going to find it. Why can’t it be LHCb?” Johnson says.

    When it is found, it’s going to turn physics as we know it on its head, he says. “It would be one of the biggest discoveries in the last hundred years. It would completely change the way we view our universe.”

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

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    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, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

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

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

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

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

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

    The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

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

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

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

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

    See the full article here .


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  • richardmitnick 10:05 am on July 6, 2022 Permalink | Reply
    Tags: "10 years later Higgs boson discoverers publish refined measurements", , , , , , , , Symmetry,   

    From “Symmetry”: “10 years later Higgs boson discoverers publish refined measurements” 

    Symmetry Mag

    From “Symmetry”

    07/06/22
    Madeleine O’Keefe

    1
    Courtesy of Sandbox Studio, Chicago with Corinne Mucha.

    In new papers by the CMS and ATLAS Collaborations, physicists detail high-precision results from Higgs boson studies—but no new physics (yet).

    Particle physics changed forever on July 4, 2012. That was the day the two major physics experiments at CERN’s Large Hadron Collider, CMS and ATLAS, jointly announced the discovery of a particle that matched the properties of the Higgs boson—a particle theorized decades earlier. The discovery cemented the final piece in the Standard Model of particle physics.
    _______________________________________________
    Higgs


    _______________________________________________

    In the decade since, physicists on CMS and ATLAS have studied the Higgs boson doggedly, probing its properties and teasing out its secrets.

    Today, on the 10-year anniversary of the Higgs discovery, CMS and ATLAS have released comprehensive new measurements of this particle in a special edition of the journal Nature [This special article will be posted here]. Both collaborations have measured properties of the Higgs boson more precisely than ever before, but neither has uncovered any surprises—yet.

    “The particle that was discovered [in 2012] looks more and more like the Standard Model Higgs boson,” says Kétévi Assamagan, an ATLAS physicist at the US Department of Energy’s Brookhaven National Laboratory who was convener for the experiment’s Higgs group from 2008-2010. “Nevertheless, there is room for new physics.”

    “What’s really surprising is how well the experiments have measured these properties,” says Sally Dawson, a theorist at Brookhaven and author of the book The Higgs Hunter’s Guide. “We would have never guessed it … It’s truly phenomenal.

    “Now we know a whole lot about the Higgs, because particle physics predicted how the Higgs would be produced, how it would decay, the signatures that we would see. And it appears to be that it’s happening just the way it’s predicted.”

    Liza Brost is an ATLAS physicist who has been studying the Higgs boson since its discovery—literally. (She started working at CERN on July 3, 2012.) “It’s really fun to have this new particle that we can analyze in detail and see what it is, how it behaves,” says Brost, who now works for Brookhaven.

    Daniel Guerrero, a CMS researcher at DOE’s Fermi National Accelerator Laboratory, agrees: “After we discovered the Higgs boson, it’s like a complete new field of exploration opened for experiments at the LHC.”
    __________________________________________________________
    [Earlier than the LHC at CERN, The DOE’s Fermi National Accelerator Laboratory had sought the Higgs with the Tevatron Accelerator.

    But the Tevatron could barely muster 2 TeV [Terraelecton volts], not enough energy to find the Higgs. CERN’s LHC is capable of 13 TeV.

    Another possible attempt in the U.S. would have been the Super Conducting Supercollider.

    Fermilab has gone on to become a world powerhouse in neutrino research with the LBNF/DUNE project which will send neutrinos 800 miles to SURF-The Sanford Underground Research Facility in in Lead, South Dakota.]
    __________________________________________________________

    In the last 10 years, the LHC completed its second run of data-taking, called Run 2. During this time, the collision energy was raised from 8 teraelectronvolts to 13 TeV, increasing the rate of Higgs production and resulting in much more data for the experiments to collect and analyze.

    For example, ATLAS estimates that about 9 million Higgs bosons were produced in the ATLAS detector during Run 2—30 times more than in 2012 (though they only analyze a fraction of that number).

    In the last decade, “the Higgs boson has only gotten ‘bigger,’” says Fermilab CMS researcher Nicholas Smith, speaking metaphorically (the Higgs boson mass remains approximately 125 GeV, now measured to a precision of 0.1%). “We’ve only gotten better and better at seeing it.”

    Precision measurements

    Higgs bosons are created by accelerating beams of protons around the LHC’s 17-mile-circumference circular tunnel at close to the speed of light. Two beams travel in opposite directions and collide at four points along the ring, including at the CMS and ATLAS detectors. The collisions trigger the formation of new particles that interact—sometimes turning into Higgs bosons.

    Studying the combinations of particles that can create a Higgs boson—called production channels or modes—and the particles into which it decays—called decay modes—gives physicists a better understanding of the particle.

    The new CMS and ATLAS results were obtained by combining several separate analyses of Higgs boson production modes and their corresponding decay modes.

    “The combination is basically taking the division of labor [by separate analyses] and then recombining it into something that is interpretable as one physics result,” says Smith, who is a co-convener of the CMS Higgs combination group. “The more [decay modes] you can cover, the more stringent limits you can place on the way the Higgs production behaves, and vice versa: The more production modes you look at, the more you can place stringent constraints on how it decays.”

    Some of the key measurements include how the Higgs interacts with other particles. These interactions, or couplings, are part of the mechanism by which the Higgs gives mass to other fundamental particles.

    The ATLAS collaboration measured the Higgs couplings to the top quark, bottom quark and tau lepton with uncertainties ranging from about 7% to 12%, as well as the couplings to the W and Z bosons with uncertainties of about 5%.

    Many of the Higgs properties reported in the CMS paper were measured with accuracies better than 10%, a major improvement from their 20% uncertainties in 2012.

    All the new CMS and ATLAS measurements were consistent with predictions of the Standard Model within uncertainties. But that doesn’t mean there’s no new physics to be found, says Guerrero. “There is physics in the other beyond-Standard-Model theories that still can be hidden within those uncertainties, so that’s not a stopper,” he says. “Actually, we want to go further to see if, after we go to a higher precision, we can start to see deviations.”

    Room for discovery

    Indeed, there is plenty of room for new phenomena beyond the Standard Model, as some of the Higgs boson’s key properties remain to be measured by both CMS and ATLAS. These include some of its rare decay modes and the coupling of the Higgs boson to itself.

    This Higgs boson self-coupling is a phenomenon intensely studied by CMS and ATLAS, both of which set constraints on it in their new papers. It’s also related to Higgs pair production, an extremely rare interaction in which two Higgs bosons, instead of just one, are created in a single production channel; CMS and ATLAS also established new limits on the probability of this process taking place, but did not observe it.

    Eventually observing Higgs self-coupling and Higgs pair production will allow physicists to better understand a property called the Higgs potential. This property of the field generated by the Higgs “has connections to the matter-antimatter asymmetry in the early universe, electroweak symmetry breaking, baryogenesis—all of these huge questions that we usually don’t even get close to touching on in our line of work,” says Brost.

    Now, though, physicists are looking forward to the data to be collected during LHC Run 3, which began July 5 and will last for close to four years. They all agree that the next steps for Higgs research require more data—and lots of it.

    With more data, the experimental measurements can become even more precise, and that will push theorists to calculate their predictions more precisely as well, says Dawson. One day, if a more-precise prediction diverges from the experimental measurements of the Higgs boson, it could point to new physics.

    “The discovery of the Higgs allowed us to have a bit of direction,” says Assamagan. “In the process as well, we have come up with better techniques for doing analyses [and] we’ve improved our understanding of the detectors. So, a lot of progress has been made. And I think we are certainly in a better position now to discover new physics if it is there.”

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:10 am on July 5, 2022 Permalink | Reply
    Tags: "Wait- didn’t the LHC already 'restart?' ”, , , , , , , , Symmetry   

    From “Symmetry”: “Wait- didn’t the LHC already “restart?” 

    Symmetry Mag

    From “Symmetry”

    07/05/22
    Sarah Charley

    Today marks the start of LHC Run 3. So what was #restartingLHC in April all about?

    1
    Courtesy of CERN

    Today CERN celebrates the start of #LHCRun3. For the next four years, the Large Hadron Collider will generate more proton-proton collisions than the first two runs combined. These collisions will allow scientists to study the fundamental laws of physics and search for new phenomena.

    The start of LHC Run 3 comes two months after CERN announced the LHC “restart.” So what’s the difference between “start” and “restart?”

    “Some people think we switch the LHC ‘on’ and then it’s done, but it’s a hugely complex process,” says Rende Steerenberg, head of the Operations Group in the CERN Beam Department.

    According to Steerenberg, “restart” means that protons are regularly circulating inside the LHC and that “commissioning with beam” can begin. During commissioning, scientists collect data, but it’s not for particle physics research—it’s to make sure everything is working properly.

    “We do this hand in hand with the experiments,” Steerenberg says. “We have a meeting every morning at 9 a.m. over Zoom to discuss how the last 24 hours went and to adjust where necessary the plans for the next days.”

    Scientists use these low-intensity beams to test and align thousands of individual scientific instruments. The proton beams also clean the inside of the LHC by zapping impurities that have frozen to the inside of the vacuum pipe (a process aptly named “scrubbing”).

    According to Steerenberg, the LHC and its experiments form a kind of massive orchestra. Restart is equivalent to the noisy few minutes during which all the instruments tune to “A.” The start of a run—on the other hand—is when the symphony begins. Physicists call this period “stable beams.”

    During stable beams, the LHC collides about a billion protons every second for hours on end. Massive particle detectors record what happens during these collisions, and scientists use the data for fundamental physics research. This period of intensive data collection will last for close to 4 years, with minimal pauses for refills, upgrades and repairs. But just because stable beams are back inside the LHC doesn’t mean the accelerator scientists get a break.

    “Commissioning continues even after physics starts,” Steerenberg says.

    Over the next several months, accelerator operators will continue to ramp up the intensity of the proton beams, with the goal of breaking the records they previously set during LHC Run 2.

    “Before Long Shutdown 2, we ran with 110 billion protons per beam,” Steerenberg says. “Now we will start with 120 billion and then aim for 180 billion.”

    More intensity means more data, which scientists need to see incredibly rare processes, such as the Higgs boson interacting with itself. LHC Run 3 will be the last run before the LHC is upgraded to the High Luminosity LHC, which will have a collision rate 10 times greater than the LHC’s design value.

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 1:01 pm on June 30, 2022 Permalink | Reply
    Tags: "Four things physicists still wonder about the Higgs boson", 1. Does the Higgs boson interact with itself?, 2. How does the Higgs couple to other particles?, 3. Are there other Higgs particles?, 4. Is the Higgs connected to dark matter or other unusual particles?, , Alternative theories that extend the Standard Model call for many more types of Higgs particles., , By measuring the Higgs very precisely we can gain an understanding of physics beyond the Standard Model and maybe find a portal to a new sector that is beyond the Standard Model., , , How will physicists answer these questions?, If there are other Higgs particles out there physicists hope to see their footprints in collider experiments., It took 60 years to first detect the Higgs boson and in the past 10 years we've gotten to know it quite well., , , , Symmetry, When the news of Higgs came on July 4 2012 it moved some scientists to tears., Yet there’s still a lot to learn.   

    From “Symmetry”: “Four things physicists still wonder about the Higgs boson” 

    Symmetry Mag

    From “Symmetry”

    06/30/22
    Mara Johnson-Groh

    1
    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    Scientists have learned a lot about the Higgs boson in the decade since they discovered it. But intriguing questions remain.

    Higgs

    When the news of Higgs came on July 4 2012 it moved some scientists to tears. Others jumped and cheered. After decades of anticipation, physicists had at last discovered the Higgs boson.

    In the years since that initial detection, physicists have become more and more familiar with this fundamental, force-carrying particle that is produced by the invisible field that gives particles mass. They’ve improved measurements of the Higgs boson’s mass, width, spin, couplings to different particles and other characteristics. They’ve gotten more precise measurements than they expected to be able to make.

    Yet there’s still a lot to learn. Most measurements of the Higgs haven’t yet reached the precision scientists need to differentiate between models that could lead to new insights and discoveries. Some aspects of the Higgs boson haven’t even been probed yet.

    “It took 60 years to first detect the Higgs boson and in the past 10 years we’ve gotten to know it quite well,” says Rebeca Gonzalez Suarez, a CERN physicist, the education and outreach coordinator for the ATLAS Collaboration and an associate professor at Uppsala University in Sweden. “So far it looks very normal—very much like the expectations we have of it from the Standard Model. But there’s still possibilities for it to surprise us.”

    Today, physicists are continuing to refine their measurements—and even develop ideas for future colliders—in order to fully unveil the mysteries of the Higgs boson and its place in the universe.

    “By measuring the Higgs very precisely we can gain an understanding of physics beyond the Standard Model and maybe find a portal to a new sector that is beyond the Standard Model,” says Kétévi Assamagan, a physicist at the US Department of Energy’s Brookhaven National Laboratory in New York.

    As physicists try to reach a more and more precise understanding of the Higgs, here are four questions they’re hoping to answer.

    2
    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    1. Does the Higgs boson interact with itself?

    One of the biggest questions about the Higgs is how it might interact, or couple, with itself.

    “I think this is the main question about the Higgs right now,” says Caterina Vernieri, assistant professor and a Panofsky Fellow at SLAC National Accelerator Laboratory. “It’s really an unknown cornerstone in our understanding of the Higgs.”

    Experiments have shown the Higgs couples with other particles [providing mass], including a menagerie of fundamental particles like the W and Z bosons, quarks, taus and muons. According to the Standard Model, it’s also expected to couple with itself.

    Uncovering the exact details of how this happens could help physicists further refine the Standard Model, and even shed light on the evolution of the early universe and the matter and antimatter imbalance.

    If physicists learn that the Higgs boson does not interact with itself in the manner predicted by the Standard Model, it could upend their understanding of the particle and suggest that the universe isn’t in the energy state that physicists predict, which could affect the rules of how matter interacts.

    To find out if the Higgs self-couples, physicists are looking at particle collisions for hints of Higgs boson pairs, or even rarer Higgs boson triplets, which would only be created if the Higgs self-couples.

    Thus far, data from experiments at CERN’s Large Hadron Collider haven’t yet seen a pair of Higgs bosons, but they also haven’t ruled out the possibility—there just simply isn’t enough data yet.

    According to predictions from the Standard Model, the self-coupling should produce pairs of Higgs bosons infrequently at collider experiments—over 1,000 times less often than a single Higgs boson is produced.

    Physicists are hoping that future runs will be able to help narrow this down as the LHC turns out more Higgs boson-producing events.

    3
    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    2. How does the Higgs couple to other particles?

    While physicists don’t yet know if the Higgs couples to itself, they do know it couples to other particles. In some cases—as with the top quark, the heaviest of the Standard Model particles—the coupling is quite well understood. But physicists are just starting to get a handle on how much other particles, like the comparatively lighter muon, interact with Higgs bosons.

    How much a given particle will couple with a Higgs is predicted by the Standard Model and is related to the particle’s mass: The more massive the particle, the greater the coupling. So far, measurements of couplings match these predictions. But the precision of these measurements isn’t yet great enough to see if there could be any deviations from the Standard Model. Knowing exactly how the Higgs couples can help scientists understand how particles get their mass.

    “If we see any discrepancies when we take precision measurements of the Higgs boson coupling with other particles, that can tell us if there is new physics out there,” Vernieri says.

    3
    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    3. Are there other Higgs particles?

    So far, physicists have found only one Higgs boson, which is what the Standard Model predicts. But some alternative theories that extend the Standard Model call for many more types of Higgs particles.

    “There is no reason why there shouldn’t be more,” says Sally Dawson, a theoretical particle physicist at Brookhaven National Laboratory.

    “There’s a whole host of possibilities on what that could look like.”

    Some models suggest there’s a version of the Higgs that has different properties from the boson we know. The Higgs boson discovered in 2012 has zero spin and no electric charge, but other Higgs particles could have different characteristics. Other models propose there’s one type of Higgs that interacts with heavy particles and another that interacts with lighter particles. Or maybe the Higgs particle we see is really a composite of multiple different particles.

    “Any additional Higgs that we may discover would indicate that there must be new physics,” Assamagan says. “It could help us explain some of the things that don’t necessarily fit in the Standard Model.”

    Some phenomena that could be explained by additional Higgs particles include dark matter, neutrino oscillations, the mystery of neutrino masses, and why there’s an imbalance of matter and antimatter in the universe.

    If there are other Higgs particles out there physicists hope to see their footprints in collider experiments.

    4
    Illustration by Sandbox Studio, Chicago with Corinne Mucha.

    4. Is the Higgs connected to dark matter or other unusual particles?

    Because the Higgs boson helps explain where mass comes from, many scientists think it should interact with dark matter: the mysterious substance that seems to be connected with everyday matter only through gravity.

    “The Higgs could be the portal between us and this dark sector that could hide dark matter,” Gonzalez Suarez says.

    Certain theories predict that dark matter interacts with normal matter by swapping Higgs bosons. If this is the case, then a collision that produces Higgs particles could also create dark matter particles.

    “The Higgs in the Standard Model doesn’t decay into dark matter, but some models suggest there’s an interaction,” Dawson says. “It’s very possible that measuring Higgs properties could tell you something about dark matter.”

    In other scenarios, when the Higgs decays, it could produce other completely new, invisible particles that physicists haven’t even considered. No unusual particles have been seen in collider experiments—where their existence would be inferred from missing energy in the aftermath of a collision—but physicists aren’t done looking.

    How will physicists answer these questions?

    Physicists are studying the Higgs at the LHC, which is just ramping up again after a three-year hiatus following upgrades to the experiments and accelerator complex and pandemic delays. These upgrades are intended to allow physicists to make more precise measurements of the Higgs boson. However, unless there are very big discrepancies, this precision is probably not enough to see if there are any deviations from the Standard Model.

    After the current run, which is scheduled to last until the end of 2025, the LHC will receive another upgrade that will transform the accelerator into the next-generation High-Luminosity LHC, which is scheduled to run until about 2040. This will allow physicists to measure how the Higgs couples to other particles down to around 5% uncertainty. While physicists expect to produce more Higgs bosons during this high-luminosity phase, measuring self-coupling will still be a challenge.

    In the long term, scientists are thinking about ways to study Higgs bosons beyond the LHC, which was designed to study a large range of phenomena via proton-proton collisions. Protons collide in a wide variety of ways, giving scientists a lot of ground to cover when they’re not sure where to look. But they’re messy, which can make it hard to pinpoint specific types of particles and events.

    That’s why some scientists have proposed a future “Higgs factory,” which they could tune specifically to produce many Higgs bosons. Instead of colliding protons, a Higgs factory would collide matter and antimatter pairs, such as electrons and positrons. These particles would annihilate one another, eliminating much of the messiness of the collisions observed at the LHC and allowing scientists to take a closer look at the Higgs bosons produced. Such an instrument should enable scientists to reach 1% accuracy for precision measurements of most couplings and probe theoretical predictions for Higgs self-coupling.

    In the meanwhile, physicists aren’t out of hope that something unexpected will show up in ongoing experiments. With each upgrade to the LHC, there’s a chance physicists could see new particles or connections to new, hidden sectors. Or perhaps unexpected factors could allow, for example, pairs of Higgs to be produced in larger quantities than anticipated, Gonzalez Suarez says.

    “You never know with experimental science,” Dawson says. “It’s always exciting because there are so many possibilities, and we don’t know which one is right.”

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
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