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  • richardmitnick 10:43 am on September 20, 2020 Permalink | Reply
    Tags: "Physicists May Have The First Experimental Evidence of a New Type of Dark Boson", Aarhus Universitet DK, , , , Dark Matter,   

    From MIT and Aarhus Universitet DK: “Physicists May Have The First Experimental Evidence of a New Type of Dark Boson” 

    MIT News

    From MIT

    and

    Aarhus Universitet DK

    via

    ScienceAlert

    Science Alert

    20 SEPTEMBER 2020
    MIKE MCRAE

    1
    (cokada/iStock/Getty Images)

    Two experiments hunting for a whisper of a particle that prevents whole galaxies from flying apart recently published some contradictory results. One came up empty handed, while the other gives us every reason to keep on searching.

    Dark bosons are Dark Matter candidates based on force-carrying particles that don’t really pack much force.

    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.

    Unlike the bosons we’re more familiar with, such as the photons that bind molecules and the gluons that hold atomic nuclei together, an exchange of dark bosons would barely affect their immediate surroundings.

    If they existed, on the other hand, their collective energy could be responsible for making up dark matter – the missing mass that provides the extra gravity needed to keep our Universe of stars in their familiar formations.

    Unfortunately, the presence of such bosons would be about as detectable as a murmur in a storm. For a physicist, however, a murmur might be enough to still be noticeable given the right kind of experiment.

    The two studies – one led by researchers from the Massachusetts Institute of Technology (MIT), the other by Aarhus University in Denmark – looked for subtle differences in the positioning of an electron in an isotope as it jumped between energy levels. If it swayed, this could be a telltale sign of a dark boson’s nudge.

    That boson, in theory, would come from an interaction between the orbiting electron and the quarks making up neutrons in the atom’s nucleus.

    The MIT-led team used a handful of ytterbium isotopes for their experiment, while calcium was the element of choice for the Aarhus University-led group.

    Both experiments lined up their data on a type of plot specific to measuring these kinds of movements in isotopes. While the calcium-based experiment appeared as predicted, the ytterbium plot was off, with a statistically significant deviation in the plot’s linearity.

    This isn’t a cause for celebration of any sort. For one thing, while a boson could explain the numbers, so could a difference in the way they carry out calculations, a type of correction called a quadratic field shift.

    Exactly why one experiment might have found something odd and the other found nothing at all is also in need of an explanation.

    As always, we need more data. A lot more. But figuring out exactly what makes up more than a quarter of the Universe is one of the biggest questions in science, so any potential leads are going to be pursued with excitement.

    Adding new kinds of force-carrying particles to the Standard Model isn’t exactly ruled out by anything in physics, but finding one would be a huge deal.

    Last year physicists were excited by particles moving away at weird angles, hinting at a hitherto unknown force at work.

    Similarly, the number of electrons recoiling in the XENON1T dark matter setup got tongues wagging early this year, inviting speculation over a hypothetical dark matter candidate called an axion.

    As interesting as these results are, we’ve had our hearts broken before. In 2016, a type of dark matter candidate called a Madala Boson was rumoured to have been spotted among data collected by the Large Hadron Collider in its search for the Higgs particle.

    This particle could be thought of as a kind of dark version of the Higgs boson, lending dark matter its strength without making itself clear in any other way.

    CERN threw cold water over that bit of gossip, sad to say. Which doesn’t mean such a particle doesn’t exist, or that signs aren’t tempting – just that we can’t confirm it with any real degree of confidence.

    Bigger colliders, more sensitive equipment, and clever new ways to search for subtle nudges and whispers of virtually non-existent particles might one day get us the answers we need.

    Dark matter sure isn’t going to make it easy.

    This research was published in papers from each group:

    Evidence for Nonlinear Isotope Shift in Yb+ Search for New Boson
    Physical Review Letters

    and

    Improved Isotope-Shift-Based Bounds on Bosons beyond the Standard Model through Measurements of the 2D3/2−2D5/2 Interval in Ca+
    Physical Review Letters

    See the full article here.

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    Aarhus Universitet DK campus.

    Aarhus Universitet, abbreviated AU) is the largest and second oldest research university in Denmark. The university belongs to the Coimbra Group, the Guild, and Utrecht Network of European universities and is a member of the European University Association.

    The university was founded in Aarhus, Denmark, in 1928 and comprises five faculties in Arts, Natural Sciences, Technical Sciences, Health, and Business and Social Sciences and has a total of twenty-seven departments. It is home to over thirty internationally recognised research centres, including fifteen Centres of Excellence funded by the Danish National Research Foundation. The university is ranked among the top 100 world’s best universities. The business school within Aarhus University, called Aarhus BSS, holds the EFMD (European Foundation for Management Development) Equis accreditation, the Association to Advance Collegiate Schools of Business (AACSB) and the Association of MBAs (AMBA). This makes the business school of Aarhus University one of the few in the world to hold the so-called Triple Crown accreditation. Times Higher Education ranks Aarhus University in the top 10 of the most beautiful universities in Europe (2018).

    The university’s alumni include Bjarne Stroustrup, the inventor of programming language C++, Queen Margrethe II of Denmark, Crown Prince Frederik of Denmark, and Anders Fogh Rasmussen, former Prime Minister of Denmark and a Secretary General of NATO.

    Nobel Laureate Jens Christian Skou (Chemistry, 1997), conducted his groundbreaking work on the Na/K-ATPase in Aarhus and remained employed at the university until his retirement. Two other nobel laureates: Trygve Haavelmo (Economics, 1989) and Dale T. Mortensen (Economics, 2010). were affiliated with the university.

    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

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    USPS “Forever” postage stamps celebrating Innovation at MIT

    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.

    MIT Campus

     
  • richardmitnick 11:02 am on September 18, 2020 Permalink | Reply
    Tags: "The Big Freeze: How the universe will die", , , , , , , Dark Matter   

    From Astronomy Magazine: “The Big Freeze: How the universe will die” 

    From Astronomy Magazine

    September 10, 2020
    Eric Betz

    The cosmos will come to a close through a cold and lonely death called the Big Freeze.

    1
    The region surrounding Sagittarius A*, the Milky Way’s own supermassive black hole. Eventually, black holes will be the last remaining matter in the universe. Credit: NASA/JPL-Caltech/Judy Schmidt.

    The cosmos may never end. But if you were immortal, you’d probably wish it would. Our cosmos’ final fate is a long and frigid affair that astronomers call the Big Freeze, or Big Chill.

    It’s a fitting description for the day when all heat and energy is evenly spread over incomprehensibly vast distances. At this point, the universe’s final temperature will hover just above absolute zero.

    The Big Bang’s accelerating expansion

    Some 13.8 billion years ago, our universe was born in the Big Bang, and it’s been expanding ever since.

    Until a few decades ago, it looked like that expansion would eventually end. Astronomers’ measurements suggested there was enough matter in the universe to overcome expansion and reverse the process, triggering a so-called Big Crunch. In this scenario, the cosmos would collapse back into an infinitely dense singularity like the one it emerged from. Perhaps this process could even spark another Big Bang, the thinking went.

    We’d be gone, but the Big Bang/Big Crunch cycle could infinitely repeat.

    In the years since then, the discovery of dark energy has robbed us of a shot at this eternal rebirth. In 1998, two separate teams of astronomers announced that they’d measured special exploding stars in the distant universe, called a type Ia supernova, which serves as “standard candles” for calculating distances. They found that the distant explosions — which should all have the same intrinsic brightness — were dimmer, and therefore farther away, than expected. Some mysterious force was pushing the cosmos apart from within.

    This dark energy is now thought to make up some 69 percent of the universe’s mass, while dark matter accounts for another roughly 26 percent. Normal matter — people, planets, stars, and anything else you can see — comprises just about 5 percent of the cosmos.

    The most important impact of dark energy is that the universe’s expansion will never slow down. It will only accelerate.

    Heat death of the universe

    Decades of observations have only confirmed researchers’ findings. All signs now point to a long and lonely death that peters out toward infinity. The scientific term for this fate is “heat death.”

    But things will be rather desolate long before that happens.

    “Just” a couple trillion years from now, the universe will have expanded so much that no distant galaxies will be visible from our own Milky Way, which will have long since merged with its neighbors. Eventually, 100 trillion years from now, all star formation will cease, ending the Stelliferous Era that’s be running since not long after our universe first formed.

    Much later, in the so-called Degenerate Era, galaxies will be gone, too. Stellar remnants will fall apart. And all remaining matter will be locked up inside black holes.

    In fact, black holes will be the last surviving sentinels of the universe as we know it. In the Black Hole Era, they’ll be the only “normal” matter left. But eventually, even these titans will disappear, too.

    Stephen Hawking predicted that black holes slowly evaporate by releasing their particles into the universe. First, the smaller, solar-mass black holes will vanish. And by a googol years into the future (a 1 followed by 100 zeroes), Hawking radiation will have killed off even the supermassive black holes.

    No normal matter will remain in this final “Dark Era” of the universe, which will last far longer than everything that came before it. And the second law of thermodynamics tells us that in this time frame, all energy will ultimately be evenly distributed. The cosmos will settle at its final resting temperature, just above absolute zero, the coldest temperature possible.

    If this future seems dark and depressing, take comfort in knowing that every earthling will have died long before we have to worry about it. In fact, on this timescale of trillions of years, even the existence of our entire species registers as but a brief ray of sunlight before an infinite winter of darkness.

    See the full article here .


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    Astronomy is a magazine about the science and hobby of astronomy. Based near Milwaukee in Waukesha, Wisconsin, it is produced by Kalmbach Publishing. Astronomy’s readers include those interested in astronomy and those who want to know about sky events, observing techniques, astrophotography, and amateur astronomy in general.

    Astronomy was founded in 1973 by Stephen A. Walther, a graduate of the University of Wisconsin–Stevens Point and amateur astronomer. The first issue, August 1973, consisted of 48 pages with five feature articles and information about what to see in the sky that month. Issues contained astrophotos and illustrations created by astronomical artists. Walther had worked part time as a planetarium lecturer at the University of Wisconsin–Milwaukee and developed an interest in photographing constellations at an early age. Although even in childhood he was interested to obsession in Astronomy, he did so poorly in mathematics that his mother despaired that he would ever be able to earn a living. However he graduated in Journalism from the University of Wisconsin Stevens Point, and as a senior class project he created a business plan for a magazine for amateur astronomers. With the help of his brother David, he was able to bring the magazine to fruition. He died in 1977.

     
  • richardmitnick 11:14 am on September 9, 2020 Permalink | Reply
    Tags: "Lead Lab Selected for Next-Generation Cosmic Microwave Background Experiment", , , , , CMB-S4 project will feature new telescopes at the South Pole and also in Chile’s Atacama high desert., CMB-S4 will unite several existing collaborations to survey the microwave sky in unprecedented detail with 500000 ultrasensitive detectors for 7 years., , , Dark Matter, , This project will involve 21 telescopes in two of our planet’s prime places for viewing deep space.   

    From Lawrence Berkeley National Lab: “Lead Lab Selected for Next-Generation Cosmic Microwave Background Experiment” 


    From Lawrence Berkeley National Lab

    September 9, 2020
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 520-0843

    U.S. DOE selects Berkeley Lab to lead DOE/NSF experiment that combines observatories at the South Pole and in Chile’s Atacama high desert.

    1
    The South Pole Telescope scans the sky as the southern lights, or aurora australis, form green patterns in this 2018 video clip. The CMB-S4 project will feature new telescopes around this site of current experiments at the South Pole, and also in Chile’s Atacama high desert. (Credit: Robert Schwarz/University of Minnesota.)

    The largest collaborative undertaking yet to explore the relic light emitted by the infant universe has taken a step forward with the U.S. Department of Energy’s selection of Lawrence Berkeley National Laboratory (Berkeley Lab) to lead the partnership of national labs, universities, and other institutions that will carry out the DOE roles and responsibilities for the effort. This next-generation experiment, known as CMB-S4, or Cosmic Microwave Background Stage 4, is being planned to become a joint DOE and National Science Foundation project.

    2
    The ‘Stage-4’ ground-based cosmic microwave background (CMB) experiment, CMB-S4, consisting of dedicated telescopes equipped with highly sensitive superconducting cameras operating at the South Pole, the high Chilean Atacama plateau, and possibly northern hemisphere sites, will provide a dramatic leap forward in our understanding of the fundamental nature of space and time and the evolution of the Universe. CMB-S4 will be designed to cross critical thresholds in testing inflation, determining the number and masses of the neutrinos, constraining possible new light relic particles, providing precise constraints on the nature of dark energy, and testing general relativity on large scales.

    CMB-S4 will unite several existing collaborations to survey the microwave sky in unprecedented detail with 500,000 ultrasensitive detectors for 7 years. These detectors will be placed on 21 telescopes in two of our planet’s prime places for viewing deep space: the South Pole and the high Chilean Atacama desert. The project is intended to unlock many secrets in cosmology, fundamental physics, astrophysics, and astronomy.

    Combining a mix of large and small telescopes at both sites, CMB-S4 will be the first experiment to access the entire scope of ground-based CMB science. It will measure ever-so-slight variations in the temperature and polarization, or directionality, of microwave light across most of the sky, to probe for ripples in space-time associated with a rapid expansion at the start of the universe known as Inflation.

    Inflation

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

    HPHS Owls

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


    Alan Guth’s notes:

    Alan Guth’s original notes on inflation

    3
    This image, from “Eternal Sky,” a video series about the Simons Observatory, shows the Atacama Desert site where some of the telescopes for the CMB-S4 experiment will be built. (Credit: Copyright Debra Kellner/Simons Foundation.)

    CMB-S4 will also help to measure the mass of the neutrino; map the growth of matter clustering over time in the universe; shed new light on mysterious Dark Matter, which makes up most of the universe’s matter but hasn’t yet been directly observed, and Dark Energy, which is driving an accelerating expansion of the universe; and aid in the detection and study of powerful space phenomena like gamma-ray bursts and jet-emitting blazars.

    Gamma-ray burst credit NASA SWIFT/Cruz Dewilde.

    NASA Neil Gehrels Swift Observatory.

    On Sept. 1, DOE Office of Science Director Chris Fall authorized the selection of Berkeley Lab as the lead laboratory for the DOE roles and responsibilities on CMB-S4, with Argonne National Laboratory, Fermi National Accelerator Laboratory, and SLAC National Accelerator Laboratory serving as partner labs.

    The CMB-S4 collaboration now numbers 236 members at 93 institutions in 14 countries and 21 U.S. states.

    The project passed its first DOE milestone, known as Critical Decision 0 or CD-0, on July 26, 2019. It has been endorsed by the 2014 report of the Particle Physics Project Prioritization Panel (known as P5), which helps to set the future direction of particle physics-related research. The project also was recommended in the National Academy of Sciences Strategic Vision for Antarctic Science in 2015, and by the Astronomy and Astrophysics Advisory Committee in 2017.

    Berkeley Lab Director Michael Witherell said, “The community of CMB scientists has come together to form a strong collaboration with a unified vision of what is needed for the next generation of discovery,” adding, “We will work with the universities and other laboratories, supported by the DOE and the NSF, to turn this vision into a CMB observatory that has unprecedented power and resolution.”

    5
    A view of the South Pole Telescope, one of the existing instruments at the South Pole site where CMB-S4 will be built. (Credit: Argonne National Laboratory.)

    The NSF has been key to the development of CMB-S4, which builds on NSF’s existing program of university-led, ground-based CMB experiments. Four of these experiments – the Atacama Cosmology Telescope and POLARBEAR/Simons Array in Chile, and the South Pole Telescope and BICEP/Keck at the South Pole – helped to start CMB-S4 in 2013, and the design of CMB-S4 relies heavily on technologies developed and deployed by these teams and others.

    Princeton Atacama Cosmology Telescope, on Cerro Toco in the Atacama Desert in the north of Chile, near the Llano de Chajnantor Observatory, Altitude 4,800 m (15,700 ft).

    Princeton ACT Telescope, on Cerro Toco in the Atacama Desert in the north of Chile, near the Llano de Chajnantor Observatory, Altitude 4,800 m (15,700 ft).

    POLARBEAR McGill Telescope located in the Atacama Desert of northern Chile in the Antofagasta Region. The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve.

    BICEP 3 at the South Pole.

    NSF is also helping to plan its possible future role with a grant awarded to the University of Chicago.

    The CMB-S4 collaboration was established in 2018, and its current co-spokespeople are Julian Borrill, head of the Computational Cosmology Center at Berkeley Lab and a researcher at UC Berkeley’s Space Sciences Laboratory, and John Carlstrom, a professor of physics, astronomy, and astrophysics at the University of Chicago and scientist at Argonne Lab.

    CMB-S4 builds on decades of experience with ground-based, satellite, and balloon-based experiments, and Berkeley Lab has had a prominent role in CMB research for decades, noted Natalie Roe, Berkeley Lab’s associate laboratory director for the Physical Sciences Area.

    Berkeley Lab’s George Smoot, for example, shared the Nobel Prize in Physics in 2006 for leading a research team that discovered ever-slight temperature variations in the CMB light.

    Adrian Lee, a Berkeley Lab physicist and UC Berkeley professor, has served on the leadership teams for a number of precursor experiments to CMB-S4, including POLARBEAR/Simons Array and the Simons Observatory. Lee noted that the Simons Observatory and POLARBEAR have contributed design elements that are relevant to CMB-S4 – such as in the areas of optics and cryogenics.

    Borrill pioneered the use of supercomputers for CMB data analysis, led data management for the CMB research community for the past two decades at the DOE’s National Energy Research Scientific Computing Center (NERSC), and has served as the U.S. computational systems architect for the European Space Agency/NASA Planck satellite mission, which probed the CMB in great detail.

    NERSC at LBNL

    NERSC Cray Cori II supercomputer, named after Gerty Cori, the first American woman to win a Nobel Prize in science

    NERSC Hopper Cray XE6 supercomputer, named after Grace Hopper, One of the first programmers of the Harvard Mark I computer

    NERSC Cray XC30 Edison supercomputer

    NERSC GPFS for Life Sciences


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF computer cluster in 2003.

    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    Future:

    Cray Shasta Perlmutter SC18 AMD Epyc Nvidia pre-exascale supeercomputer

    NERSC is a DOE Office of Science User Facility.

    CMB per ESA/Planck

    ESA/Planck 2009 to 2013

    “What’s new about CMB-S4 is not the technology itself,” Borrill said, “but the scale at which we plan to deploy it – the sheer number of detectors, scale of the readout systems, number of telescopes, and volume of data to be processed.”

    Roe noted that Berkeley Lab has particular expertise in data management, and in the design and fabrication of detectors for CMB experiments.

    “This is a very big project,” Roe said. “We plan to staff up and bring in all of the expertise and capabilities from our sister labs and from the university community.”

    CMB-S4 will exceed the capabilities of earlier generations of experiments by more than 10 times. It will have the combined viewing power of three large and 18 small telescopes. The major technology challenge for CMB-S4 is in its scale. While previous generations of instruments have used tens of thousands of detectors, the entire CMB-S4 project will require half a million.

    The latest detector design, adapted from current experiments, will feature over 500 silicon wafers that each contain 1,000 superconducting detectors, on average – some wafers will contain up to 2,000 detectors.

    6
    This prototype wafer, measuring about 5 inches across, with over 1,000 detectors, was made to test detector fabrication processes and detector quality for the CMB-S4 experiment. (Photo courtesy of Aritoki Suzuki/Berkeley Lab)

    Aritoki Suzuki, a Berkeley Lab staff scientist, who is a detector team co-lead for CMB-S4, has been working with industry to develop faster and cheaper manufacturing processes for the detectors, as an option that can be considered, and noted that multiple manufacturing sites at research institutions are needed, too.

    “Delivering nearly 500,000 detectors will be one of the biggest challenges of the project,” Suzuki said. “We will combine forces from national labs, universities, and industry partners to tackle this immense task.”

    Another major hardware focus for the project will be the construction of new telescopes. The data-management challenges will be substantial, too, as these huge arrays of detectors will produce 1,000 times more data than the Planck satellite.

    CMB-S4 plans to draw upon computing resources at Berkeley Lab’s NERSC and the Argonne Leadership Computing Facility (ALCF), and to apply to NSF’s Open Science Grid and eXtreme Science and Engineering Discovery Environment (XSEDE).

    The project is hoping to deploy its first telescope in 2027, to be fully operational at all telescopes within a couple of years, and to run through 2035.

    Next steps include preparing a project office at Berkeley Lab, getting ready for the next DOE milestone, known as Critical Decision 1, working toward becoming an NSF project, and working across the community to bring in the best expertise and capabilities.

    ALCF and NERSC are DOE Office of Science user facilities.

    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

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

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

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

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

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

    See the full article here .

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    LBNL campus

    LBNL Molecular Foundry

    Bringing Science Solutions to the World
    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

     
  • richardmitnick 8:42 am on September 9, 2020 Permalink | Reply
    Tags: "Quieting the quantum realm", , , Dark Matter, LUX-ZEPLIN (LZ) dark matter experiment, LUX-ZEPLIN collaboration publishes 1200 assays- creates library for future rare event searches., , , The quantum soundscape is a boisterous one-turning down the volume.,   

    From Sanford Underground Research Facility: “Quieting the quantum realm” 

    SURF logo

    From Sanford Underground Research Facility


    Homestake Mining Company

    September 4, 2020
    Erin Lorraine Broberg

    LUX-ZEPLIN collaboration publishes 1,200 assays, creates library for future rare event searches.

    1
    Brianna Mount at work in the Black Hills State University Underground Campus (BHUC) at Sanford Lab, where components of the LUX-ZEPLIN experiment were tested to better understand backgrounds of the materials. Credit: Photo by Matthew Kapust.

    The subatomic world just got a lot quieter for the LUX-ZEPLIN (LZ) dark matter experiment [below].

    Currently being assembled on the 4850 Level of Sanford Underground Research Facility (Sanford Lab), LZ will search for theoretical dark matter particles, known as WIMPs. In a paper recently accepted for publication in the European Physics Journal, the LZ collaboration shared the results of more than 1,200 assays with the scientific community. These results describe the levels of radioactive decay of the detector components and effectively create a library of resources for future experiments.

    “This effort dramatically increases our ability to seek out dark matter signals in our detector,” said Kevin Lesko, spokesperson for the LZ collaboration and lead for the low-background effort. “The whole experiment participated in this effort; everyone understood the importance of achieving a very low background level and a strong background model.”

    The paper, entitled “The LUX-ZEPLIN radioactivity and cleanliness control programs,” details the results of assays completed by the collaboration at the Black Hills State University Underground Campus (BHUC), Boulby Underground Germanium Suite (BUGS) and the Berkeley Low Background Facility (BLBF).

    What’s that sound?

    The quantum soundscape is a boisterous one.

    A constant barrage of cosmic rays from our Sun showers the Earth, reverberating through matter. Atoms decay and reconfigure. Protons pop free from one nucleus only to be picked up by another. Electrons, stripped from their orbit, are sent ricocheting through surrounding matter. And though we normally think of radiation in the context of X-ray machines and nuclear power sources, everything—from bananas to skin cells to dust—contributes to a constant hum of background radiation in our world.

    Most of us are oblivious to this ongoing racket. Particle physicists are not.

    Experiments searching for extremely rare particle interactions (like interactions with dark matter particles) are most bothered by this noise. When they tune their experiments to eavesdrop on the particle world, they get a deafening cacophony that obscures the very signal they want to hear. Physicists call this effect “background.”

    Turning down the volume

    Before looking for dark matter, LZ physicists needed to turn down the volume.

    First, LZ researchers constructed the experiment’s inner detector inside a class-1000 cleanroom, requiring everyone to wear a full body clean suit before entering. This prevented dust, a source of radioactive decay, from accumulating on the detector. During months of assembly, less than one gram of dust accumulated on the surface of the 5,000 pound, 9-foot-tall inner detector after remedial cleaning.

    2
    Researchers examine the foil-wrapped LUX-ZEPLIN inner detector that was assembled in a class-100 cleanroom in the Surface Assembly Lab at Sanford Lab. Photo by Matthew Kapust.

    Next, the detector was transported nearly a mile underground to the 4850 Level of Sanford Lab. There, the rock overburden shields the experiment from the Sun’s cosmic rays. In the underground cavern, they inserted the detector inside a water tank that will be filled with more than 200 tons of deionized water. This liquid shield will absorb radiation emanating from the cavern’s rock or other experiment support systems.

    But what about the detector itself? How could researchers be sure the materials used to build the detector wouldn’t create backgrounds of their own?

    Testing every component

    “Early on, we decided we wanted the backgrounds in the experiment to be dominated by nature—by things we can’t eradicate, like neutrinos—not by the materials we were using to build the detector,” Lesko said.

    The collaboration’s recent paper is the result of efforts to assay, or test, nearly every component that went into the detector.

    “We required every subsystem to send in samples for testing,” Lesko said. “At this point, we’ve assayed every nut, every screw, every washer, every component. We either have a characteristic assay of the raw materials, or of the finished component.”

    Of the 1,200 assays in the publication, 969 assays used high purity germanium (HP Ge) to examine the radiopurity of components. Roughly seventy percent of the HP Ge assays were completed by the BHUC on the 4850 Level of Sanford Lab. Working one sample at a time, researchers placed LZ’s components inside detectors for weeks at a time, quietly listening to and recording the noise they produced.

    3
    In the BHUC, this low background counter uses a high purity germanium detector to assay materials, telling researchers more about a given materials radiopurity or “quietness.” Photo by Matthew Kapust.

    “In the past five years, the majority of the samples counted at the BHUC have been for the LZ experiment,” said Brianna Mount, director of the BHUC. “This paper is the culmination of that effort, and it demonstrates what the BHUC is capable of doing for the scientific community.”

    Using this process, researchers learned that some materials were 10 to 100 times more radioactive than others. This helped researchers make informed decisions when selecting materials. In some cases, they even worked with manufacturers to redesign components to have lower backgrounds. Finally, researchers tallied the collective backgrounds of all the components to better understand how much interference they can expect to see when they turn on the detector.

    “This effort gives us a very strong prediction of the limits of the radioactive components as we try to decipher dark matter signals from backgrounds,” Lesko said.

    4
    The LZ dark matter experiment is being assembled inside a large water tank on the 4850 Level of Sanford Lab. LZ will search for theoretical dark matter particles, known as WIMPs. Photo by Nick Hubbard.

    Sharing a library of information

    As physicists continue to probe the inner workings of the Universe, they will continue to battle the background noise it produces.

    “The physics community is already planning for the next generation of experiments, and those experiments will require even more stringent background controls than we did with LZ,” Lesko said. “With this massive publication of assays, the next generation of experiments will have a library assays, telling them what materials to seek out and where further improvements can be made.”

    While testing detector components transformed the backgrounds of LZ, publishing those tests will provide invaluable information to future scientists tuning in to the subatomic world.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.

    LBNL LZ project at SURF, Lead, SD, USA, will replace LUX at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    LUX’s mission was to scour the universe for WIMPs, vetoing all other signatures. It would continue to do just that for another three years before it was decommissioned in 2016.

    In the midst of the excitement over first results, the LUX collaboration was already casting its gaze forward. Planning for a next-generation dark matter experiment at Sanford Lab was already under way. Named LUX-ZEPLIN (LZ), the next-generation experiment would increase the sensitivity of LUX 100 times.

    SLAC physicist Tom Shutt, a previous co-spokesperson for LUX, said one goal of the experiment was to figure out how to build an even larger detector.
    “LZ will be a thousand times more sensitive than the LUX detector,” Shutt said. “It will just begin to see an irreducible background of neutrinos that may ultimately set the limit to our ability to measure dark matter.”
    We celebrate five years of LUX, and look into the steps being taken toward the much larger and far more sensitive experiment.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

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


    LBNE

    U Washington Majorana Demonstrator Experiment at SURF

    The MAJORANA DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment in the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV. MAJORANA plans to collaborate with GERDA for a future tonne-scale 76Ge 0νββ search.

    CASPAR at SURF.

    CASPAR experiment target at SURF.

    CASPAR is a low-energy particle accelerator that allows researchers to study processes that take place inside collapsing stars.

    The scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR). CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”

     
  • richardmitnick 10:23 am on August 28, 2020 Permalink | Reply
    Tags: "There's a Strange Glow in The Centre of Our Galaxy And It's Not What We Thought It Was", , , , , Dark Matter, GCE-Galactic Center GeV Excess, , ,   

    From UC Irvine via Science Alert: “There’s a Strange Glow in The Centre of Our Galaxy, And It’s Not What We Thought It Was” 

    UC Irvine bloc

    From UC Irvine

    via

    ScienceAlert

    Science Alert

    28 AUGUST 2020
    MICHELLE STARR

    1
    (NASA/DOE/Fermi LAT Collaboration)

    NASA/Fermi LAT.


    NASA/Fermi Gamma Ray Space Telescope.

    The centre of the Milky Way is glowing. Yes, there’s a big chonkin’ black hole there, and it’s a very energetic region, but there’s an additional high-energy, gamma-ray glow, above and beyond the activity we know about, and it’s something that’s yet to be explained.

    This glow is called the Galactic Center GeV Excess (GCE), and astronomers have been trying to figure it out for years. One hotly debated explanation is that the glow might theoretically be produced by the annihilation of dark matter – but new research is a nail in that idea’s coffin.

    In a series of exhaustive models that include recent developments in simulating the galactic bulge and other sources of gamma-ray emission in the galactic centre, a team of astrophysicists have ruled out dark matter annihilation as the source of the glow.

    This finding, the team says, gives dark matter less room to hide – placing stronger constraints on its properties that could aid in future searches.

    “For 40 years or so, the leading candidate for dark matter among particle physicists was a thermal, weakly interacting and weak-scale particle,” said astrophysicist Kevork Abazajian of the University of California Irvine (UCI).

    “This result for the first time rules out that candidate up to very high-mass particles.”

    The GCE was first noticed a little over a decade ago, when the Fermi Gamma-ray Space Telescope started surveying the region. Gamma rays are the highest-energy electromagnetic waves in the Universe, and they are produced by the most intense objects, such as millisecond pulsars, neutron stars, colliding neutron stars, black holes, and supernovae.

    The problem was, when it came time to analyse Fermi’s observations, after all known gamma-ray sources were subtracted, we ended up with a gamma-ray glow in the heart of the Milky Way that couldn’t be accounted for.

    In space, when you find something that can’t be accounted for, it makes sense to try to match it up with other things that can’t be accounted for – like dark matter. This is the name we give to the invisible mass that adds gravity to the Universe.

    We can detect dark matter indirectly, because things move differently from how they should if only the visible stuff was having an effect, but we don’t know what it actually is.

    However, while we can’t detect dark matter directly, it’s possible that it produces radiation we can see.

    If types of dark matter particles called Weakly Interacting Massive Particles, or WIMPs, were to collide with each other – like the collisions in particle accelerators – they would annihilate each other, exploding in a shower of other particles, including gamma-ray photons. Such collisions have been put forward as a potential mechanism producing the GCE.

    Several studies, however, have found no evidence of WIMP collisions, but this new paper is a step up, the authors say.

    “In many models, this particle ranges from 10 to 1,000 times the mass of a proton, with more massive particles being less attractive theoretically as a dark matter particle,” said UCI astrophysicist Manoj Kaplinghat.

    “In this paper, we’re eliminating dark matter candidates over the favoured range, which is a huge improvement in the constraints we put on the possibilities that these are representative of dark matter.”

    Over three years, the team pulled together a wide range of gamma-ray modelling scenarios for the galactic centre and its bulge – the tightly packed group of stars concentrated around the centre. They included all the sources they could get their hands on – star formation, the Fermi bubbles, cosmic-ray interactions with molecular gas, and neutron stars and millisecond pulsars.

    They found that, once they had factored everything in, there was very little room left for WIMP annihilation. Between all these gamma-ray sources, “there is no significant excess in the GC that may be attributed to DM annihilation,” the researchers write in their paper.

    Previous research has found that the distribution of gamma-rays in the galactic centre is also inconsistent with dark matter annihilation. If WIMPs were the culprit, the distribution would be smooth – but instead, the gamma-ray photons are distributed in clumps as you’d expect to find from point sources, like stars.

    The distribution of stars in the bulge, according to the new research, is also inconsistent with the presence of additional dark matter.

    That’s not to say the dark matter in our galactic centre couldn’t be of some hypothetical, massive, weakly interactive type. The team has just ruled those of a mass commonly searched for, and then some. The team notes that their findings still strongly favour an astrophysical origin for the GCE.

    “Our study constrains the kind of particle that dark matter could be,” Kaplinghat said. “The multiple lines of evidence for dark matter in the galaxy are robust and unaffected by our work.”

    Which means we’re just going to have to think a lot farther outside the box to find it.

    The research has been published in Physical Review D.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC Irvine Campus

    Since 1965, the University of California, Irvine has combined the strengths of a major research university with the bounty of an incomparable Southern California location. UCI’s unyielding commitment to rigorous academics, cutting-edge research, and leadership and character development makes the campus a driving force for innovation and discovery that serves our local, national and global communities in many ways.

    With more than 29,000 undergraduate and graduate students, 1,100 faculty and 9,400 staff, UCI is among the most dynamic campuses in the University of California system. Increasingly a first-choice campus for students, UCI ranks among the top 10 U.S. universities in the number of undergraduate applications and continues to admit freshmen with highly competitive academic profiles.

    UCI fosters the rigorous expansion and creation of knowledge through quality education. Graduates are equipped with the tools of analysis, expression and cultural understanding necessary for leadership in today’s world.

    Consistently ranked among the nation’s best universities – public and private – UCI excels in a broad range of fields, garnering national recognition for many schools, departments and programs. Times Higher Education ranked UCI No. 1 among universities in the U.S. under 50 years old. Three UCI researchers have won Nobel Prizes – two in chemistry and one in physics.

    The university is noted for its top-rated research and graduate programs, extensive commitment to undergraduate education, and growing number of professional schools and programs of academic and social significance. Recent additions include highly successful programs in public health, pharmaceutical sciences and nursing science; an expanding education school; and a law school already ranked among the nation’s top 10 for its scholarly impact.

     
  • richardmitnick 8:18 pm on August 14, 2020 Permalink | Reply
    Tags: , , , , , Dark Matter,   

    From AAS NOVA: “When Dark Matter Gets Fuzzy” 

    AASNOVA

    From AAS NOVA

    14 August 2020
    Susanna Kohler

    1
    This composite image reveals the central region of our galaxy at X-ray (green and blue) and radio (red) wavelengths. A new study uses the Central Molecular Zone to constrain dark matter models. [X-Ray:NASA/CXC/UMass/D. Wang et al.; Radio:NRF/SARAO/MeerKAT]

    NASA/Chandra X-ray Telescope

    SKA SARAO Meerkat telescope(s), 90 km outside the small Northern Cape town of Carnarvon, SA

    What model of Dark Matter best describes our universe? A new study uses a unique region in our own galaxy to constrain one particular model: that of fuzzy dark matter.

    2
    There are many models describing the composition and behavior of dark matter, and how its evolution has affected the structure of our universe. [AMNH]

    Observations of our universe tell us that only 15% of the universe’s matter is the ordinary baryonic matter that we’re able to see. The remaining 85% is dark matter — mysterious material that has shaped the structure and evolution of our universe via its gravitational interactions, but that doesn’t give off any light.

    Because we can’t directly observe it, dark matter is still a relative unknown — and there are many different hypothesized models that describe its nature. Is dark matter hot? Cold? Composed of subatomic particles? Or macroscopic objects like primordial black holes? There’s a model for all of these options, and the best way to test them is to compare their predictions to the actual structure that we observe.

    Constraints from an Odd Structure

    One such constraining structure is a unique region in our own galaxy: the Central Molecular Zone, or CMZ. This extremely dense, rich collection of orbiting molecular gas lies in the very center of the Milky Way and spans just a few hundred light-years in diameter. Observations suggest that the molecular gas clouds orbit in a ring or a disk with a twisted 3D shape, but the thick dust that shrouds the galactic center limits what we can learn about the CMZ directly.

    3
    Plot of gas surface density from a simulation showing the formation of the CMZ — seen as the high-density gas ring at the heart of the plot — in the center of the Milky Way. This simulation included a nuclear bulge only, with no dark-matter core from the fuzzy dark matter model. [Li et al. 2020]

    The CMZ’s shape is not its only mystery, however: we also don’t fully understand what caused this odd structure to develop. Past studies of the birth of our galaxy’s structure from a thin disk suggest that formation of the CMZ relies on a combination of the Milky Way’s barred gravitational potential and an especially dense nuclear region.

    In a new publication led by Zhi Li (Shanghai Jiao Tong University, China), a team of scientists has now used this picture to constrain a dark matter model that relies on light dark-matter particles concentrated at the center of the galaxy.

    Adding Fuzziness to the Milky Way

    4
    Zoomed-in plot of gas surface density from a simulation showing the formation of the CMZ in the center of the Milky Way. This simulation included both a nuclear bulge and a dark-matter core from the fuzzy dark matter model. [Adapted from Li et al. 2020]

    Li and collaborators conduct a series of cosmological simulations that model the formation of the Milky Way from a thin disk in a realistic gravitational potential. In some of these simulations, the authors include only a dense nuclear bulge at the center of the galaxy. In others, they also add a galaxy core consistent with the predictions of fuzzy dark matter, a model that describes the universe’s dark matter as very light bosons that exhibit wave behavior on some scales.

    The authors show that the structure and dynamics of the CMZ can be reproduced well with only an exceedingly compact nuclear bulge. But the combination of a smaller nuclear bulge and a fuzzy-dark-matter core also neatly reproduces observations, leaving the door open for this dark-matter model.

    So is our dark matter fuzzy or not? We can’t tell yet, but Li and collaborators outline some future observations — like pinning down the mass-to-light ratio in the galactic center — that will help us answer this question and better understand what’s going on with that invisible 85% of our universe’s matter.

    Citation

    “Testing the Prediction of Fuzzy Dark Matter Theory in the Milky Way Center,” Zhi Li et al 2020 ApJ 889 88.

    https://iopscience.iop.org/article/10.3847/1538-4357/ab6598

    _______________________________________________________________

    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 .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 12:30 pm on August 2, 2020 Permalink | Reply
    Tags: "An Alternative to Dark Matter Passes Critical Test", , , , , Dark Matter, , , ,   

    From Quanta Magazine via Nautilus: “An Alternative to Dark Matter Passes Critical Test” 

    From Quanta Magazine

    Via

    Nautilus

    July 2020
    Charlie Wood

    1
    A view of the center of the Milky Way galaxy. Theories of modified gravity have had a hard time describing the universe from relatively small scales like this all the way up to the scale of the universe as a whole. Credit: NASA/JPL-Caltech/ESA/CXC/STScI

    For decades, a band of rebel theorists has waged war with one of cosmology’s core concepts—the idea that an invisible, intangible form of matter forms the universe’s primary structure. This Dark Matter [see below, “Dark Matter Background” ], which seems to outweigh the stuff we’re made of 5-to-1, accounts for a host of observations: the tight cohesion of galaxies and packs of galaxies, the way light from faraway galaxies will bend on its way to terrestrial telescopes, and the mottled structure of the early universe, to name a few.

    The would-be revolutionaries seek an alternative cosmic recipe. In place of dark matter, they substitute a subtly modified force of gravity. But attempts to translate their rough idea into precise mathematical language have always run afoul of at least one key observation. Some formulations get galaxies right, some get the contortion of light rays right, but none have pierced dark matter’s most bulletproof piece of evidence: precise maps of ancient light, known as the cosmic microwave background (CMB).

    CMB per ESA/Planck

    ESA/Planck 2009 to 2013

    “A theory must do really well to agree with this data,” said Ruth Durrer, a cosmologist at the University of Geneva. “This is the bottleneck.”

    Now, two theorists say they’ve finally squeezed an alternative theory of gravity past that obstacle. Their work, which was posted online [“A new relativistic theory for Modified Newtonian Dynamics” ( https://arxiv.org/abs/2007.00082 )] in late June 2020 and has not yet passed peer review, uses a tweaked version of Einstein’s theory of gravity to reproduce an iconic map of the early universe, a feat that even some rebels feared to be impossible. “For 15 years we’ve just been dead in the water,” said Stacy McGaugh, an astronomer at Case Western Reserve University and a longtime advocate for modified-gravity theories who was not involved in the research. “It’s a huge leap forward.”

    Others agree that the model’s preliminary results appear promising. “It’s a bit baroque, but since nothing else has worked so far, I’m still impressed that it seems to work,” Durrer said.

    Most cosmologists still prefer dark matter as the simpler of the two paradigms, but they agree that the new theory could be intriguing—if it can truly match additional cosmological observations. “That would be a big barrier,” said Dan Hooper, an astrophysicist at the University of Chicago. “That would be pretty interesting.”

    Threading the Needle

    The challenges for alternative gravity theories, collectively known as modified Newtonian dynamics or MOND, were spelled out in a separate preprint [“What is the price of abandoning dark matter? Cosmological constraints on alternative gravity theories” ( https://arxiv.org/abs/2007.00555 ) ] coincidentally published the day after the latest model appeared.

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

    MOND Rotation Curves with MOND Tully-Fisher

    MOND Modified Newtonian Dynamics a Humble Introduction Marcus Nielbock

    MOND UMD

    Chief among them is recasting the leading role dark matter plays in drawing the universe together, as described by a well-established cosmological model known as Lambda cold dark matter (LCDM).

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

    Simply put, LCDM says that we wouldn’t be here without dark matter. The infant universe was so smooth that the gravitational attraction of ordinary matter alone wouldn’t have been enough to gather particles into galaxies, stars and planets. Enter dark matter particles. LCDM uses their collective bulk to sculpt normal matter into the modern cosmic structures studied by astronomers.

    LCDM became the standard model of cosmology in part because it so precisely agrees with the CMB. This map of the early universe shows almost imperceptibly thick and thin spots rippling through the cosmos. More recently, researchers have been able to measure the orientation or polarization of the CMB’s light more precisely. Any successful cosmology will need to establish a comprehensive history of the cosmos by reproducing these three observations: the CMB’s temperature, the CMB’s polarization, and the current distribution of galaxies and galaxy clusters.

    2
    Lucy Reading-Ikkanda/Quanta Magazine; source: doi: 1303.5076v3

    In the second preprint, Kris Pardo, an astrophysicist at NASA’s Jet Propulsion Laboratory, and David Spergel, director of the Center for Computational Astrophysics at the Flatiron Institute, quantified how difficult it would be for any alternative theory of gravity to compete with one particular feature of LCDM. (Quanta Magazine is an editorially independent publication sponsored by the Simons Foundation, which also funds the Flatiron Institute.) When denser zones of dark matter dragged matter toward them, eventually forming galaxies and stars, this would have largely—but not entirely—washed out the ripples initially moving through the matter. By comparing the CMB’s polarization with today’s patterns of matter, cosmologists can cleanly measure just such an effect: ripple remnants 100 times smaller than the undulations seen in the CMB persist today.

    Re-creating these and other features without LCDM’s titular ingredient, Spergel showed, requires the finest of theoretical needle threading. “We haven’t disproven the existence of all these [modified-gravity theories],” he said. “But any alternative theory has to jump through these hoops.”

    Dark Dust

    Tom Złosnik and Constantinos Skordis, theorists at the Central European Institute for Cosmology and Fundamental Physics, believe they’ve done just that—although in a way that might surprise MOND skeptics and fans alike. They managed to construct a theory of gravity that contains an ingredient that acts exactly like an invisible form of matter on cosmic scales, blurring the line between the dark matter and MOND paradigms.

    Their theory, dubbed RelMOND, adds to the equations of general relativity an omnipresent field that behaves differently in different arenas. On the grandest scales, where the universe noticeably stretches as it expands, the field acts like invisible matter. In this mode, which Złosnik refers to as “dark dust,” the field could have shaped the visible universe just as dark matter would. The model faithfully reproduces the temperature of the CMB—the result that the duo published in their preprint—and Złosnik says it can also match the polarization spectrum and the matter distribution, although they have not yet published these plots.

    “[RelMOND] cannot do worse than LCDM,” said Złosnik, because it very closely mimics that theory for the universe as a whole.

    But if we zoom in on a galaxy, where the fabric of space holds rather still, the field acts in a way that’s true to its MOND roots: It entwines itself with the standard gravitational field, beefing it up just enough to hold a galaxy together without extra matter. (The researchers aren’t yet sure how the field acts for larger clusters of galaxies, a perennial MOND sore spot, and they suggest that this intermediate scale might be a good place to look for observational clues that could set the theory apart.)

    Despite the pair’s mathematical achievement, dark matter remains the simpler theory. Constructing the new field takes four new moving mathematical parts, while LCDM handles dark matter with just one. Hooper likens the situation to a detective debating whether the person at a murder scene is the murderer, or if they were framed by the CIA. Even if the available evidence matches both theories, one requires less of a leap.

    All the same, he doesn’t begrudge others working on what he considers a cosmological conspiracy theory. “I’m glad smart people are thinking about MOND,” he said.

    Złosnik hopes dark matter will be detected soon, but in the meantime, he sees his work on MOND more as an exercise in stretching general relativity to its limits than as a full assault on the cosmological establishment. For now, he’s just pleased to have helped show that the mathematics of gravity may accommodate weirder phenomena than many thought.

    “There’s a danger of missing out on something useful just by assuming that it’s not possible,” Złosnik said. “It might point the way to something a bit more successful.”

    ______________________________________________

    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

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • 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", , , Dark Matter, , 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, XENONnT experiment   

    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 1:17 pm on June 17, 2020 Permalink | Reply
    Tags: "Surprising Signal in the XENON1T Dark Matter Experiment", , Dark Matter, , XENON1T didn’t detect dark matter but has reached the world-leading sensitivity for the search for WIMPs .   

    From Max Planck Gesellschaft Institute for Nuclear Physics: “Surprising Signal in the XENON1T Dark Matter Experiment” 


    From Max Planck Gesellschaft Institute for Nuclear Physics

    06/17/2020

    Prof. Dr. Dr. h.c. Manfred Lindner
    Phone: +496221 516800
    Email: manfred.lindner@mpi-hd.mpg.de

    PD Dr. Teresa Marrodán Undagoitia
    Phone: +496221 516803
    Email: teresa.marrodan@mpi-hd.mpg.de

    Dr. Hardy Simgen
    Phone: +496221 516530
    Email: hardy.simgen@mpi-hd.mpg.de

    1
    The core of XENON1T. ©XENON Collaboration

    Scientists from the international XENON collaboration announced today that data from their XENON1T, the world’s most sensitive dark matter experiment, show a surprising excess of events. The scientists do not claim to have found dark matter. Instead, they say to have observed an unexpected rate of events, the source of which is not yet fully understood. The signature of the excess is similar to what might result from a tiny residual amount of tritium (super heavy hydrogen), but could also be a sign of something more exciting: the existence of a new particle known as the solar axion or the indication of previously unknown properties of neutrinos.

    XENON1T was operated deep underground at the INFN Laboratori Nazionali del Gran Sasso in Italy, from 2016 to end of 2018.

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

    It was primarily designed to detect dark matter, which makes up 85% of the matter in the universe and for which there is only indirect evidence so far. XENON1T didn’t detect dark matter, but has reached the world-leading sensitivity for the search for WIMPs (Weakly Interacting Massive Particles), which are among the theoretically preferred candidates for dark matter. In addition, XENON1T was also sensitive to different types of new particles and interactions that could explain other open questions in physics. Last year, using the same detector, the XENON collaboration published in Nature the observation of the rarest nuclear decay ever directly measured.

    The XENON1T detector, optimised for the search for rarest events, was filled with 3.2 tonnes of ultra-pure, at –95°C liquefied xenon, the innermost 2.0 tonnes of which served as a target for dark matter. When a particle crosses the target, it may collide with a xenon atom generating tiny signals of light and free electrons from the hit xenon atom. Most of these interactions occur from particles that are known to exist. Thus, a number of measures was applied to reduce these disturbing background events to an unprecedentedly low level. And the scientists carefully estimated the residual number of background events. Comparing the data of XENON1T to backgrounds, they observed a surprising excess of 53 events over the expected 232 events.

    Now, where is this excess coming from?

    One explanation could be a new, previously unconsidered source of background, caused by the presence of tiny amounts of tritium in the liquid xenon. Tritium, a radioactive isotope of hydrogen with two extra neutrons, spontaneously decays by emitting an antineutrino and an electron with an energy distribution similar to what was observed. Only a few tritium atoms for every 1025 xenon atoms (corresponding to about 2.2 kg of xenon) would be sufficient to explain the excess. Currently, there are no independent measurements that could confirm or disprove the presence of tritium at that level in the detector, so a definitive answer to this explanation is not yet possible.

    More excitingly, another explanation could be the existence of a new particle. In fact, the excess observed has an energy spectrum similar to that expected from axions produced in the Sun. Axions are hypothetical particles that were proposed to understand a symmetry of nuclear forces observed in nature. The Sun may be a strong source of axions. While these solar axions are not dark matter candidates, their detection would mark the first observation of a well-motivated but not yet observed class of new particles, with a large impact on our understanding of fundamental physics, but also on astrophysical phenomena. Moreover, axions produced in the early universe could also be the source of dark matter.

    Alternatively, the excess could also be due to surprising properties of neutrinos, trillions of which pass through the detector, unhindered, every second. One explanation could be that the magnetic moment of neutrinos is larger than its value in the Standard Model of elementary particles. This would be a strong hint to some other “new physics”.

    Of the three explanations considered by the XENON collaboration, the observed excess is most consistent with a solar axion signal. In statistical terms, the solar axion hypothesis has a significance of 3.5 sigma, meaning that there is about a 2/10,000 chance that the observed excess is due to a random fluctuation (which is thus not fully excluded) rather than a signal. While this significance is fairly high, it is not large enough to conclude that axions exist. The significance of both the tritium and neutrino magnetic moment hypotheses corresponds to 3.2 sigma, meaning that they are also consistent with the data.

    XENON1T is now upgrading to its next phase, XENONnT, with an active xenon mass three times larger and a background that is expected to be lower. With better data from XENONnT, the XENON collaboration is confident it will soon find out whether this excess is a mere statistical fluke, a background contaminant, or something far more exciting: a new particle or interaction that goes beyond known physics.

    The XENON collaboration comprises 163 scientists from 28 institutions across 11 countries. Five German institutions are significantly involved: The Max Planck Institute for Nuclear Physics in Heidelberg was responsible for the light sensors, the detection of trace amounts of radioactivity in the detector material and the liquid xenon, the University of Münster developed the cryogenic distillation system for removal of radioactive impurities from liquid xenon and a general xenon purification system, the University of Mainz was responsible for the muon system and contributed substantially to the xenon recovery and storage system, and the University of Freiburg was responsible for the detector design and development of the data acquisition electronics. All institutes as well as the Karlsruhe Institute of Technology that recently joined the collaboration are involved in data analysis.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Max-Planck-Institut für Kernphysik (“MPI for Nuclear Physics” or MPIK for short) is a research institute in Heidelberg, Germany.

    The institute is one of the 80 institutes of the Max-Planck-Gesellschaft (Max Planck Society), an independent, non-profit research organization. The Max Planck Institute for Nuclear Physics was founded in 1958 under the leadership of Wolfgang Gentner. Its precursor was the Institute for Physics at the MPI for Medical Research.

    The Max Planck Society is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at Max Planck Institutes – and many of those articles are among the most-cited publications in the relevant field.

    What is the basis of this success? The scientific attractiveness of the Max Planck Society is based on its understanding of research: Max Planck Institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The Max Planck Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

    The currently 83 Max Planck Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. Max Planck Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

     
  • richardmitnick 11:57 am on June 11, 2020 Permalink | Reply
    Tags: , , Belle II KEK High Energy Accelerator, Dark Matter, , , , Z’ particle-does it exist?   

    From Pacific Northwest National Lab: “Beauty and the Search for Dark Matter” 


    From Pacific Northwest National Lab

    June 1, 2020
    Rebekah Orton

    PNNL physicists contribute to the first results from the Belle II high-energy physics experiment.

    Belle II KEK High Energy Accelerator Research Organization Tsukuba, Japan

    After years of planning, building, and calibration, researchers at the Belle II accelerator experiment in Japan have published their first physics paper.

    Their seminal work [Physical Review Letters], with contributions from teams of Pacific Northwest National Laboratory (PNNL) researchers, searched for a theorized particle Z’ (pronounced Z prime). This possible particle could decay into dark matter—the large fraction of our universe that we know exists from astrophysical measurements but haven’t yet measured or seen in the laboratory.

    Detection of Z prime and other hypothesized dark matter particles in accelerators is difficult; it requires sensitive instrumentation and the ability to collect and categorize enormous amounts of data. Belle II is the second generation of an experiment located at a high-intensity particle accelerator in Japan that crashes subatomic particles at high speeds in an effort to better understand the visible—and invisible—world around us.

    Now you see it. Now you don’t.

    Belle II works by taking very comprehensive measurements of the well-understood collision of electrons and positrons. When electrons and positrons collide, they can create and decay into other particles and release energy.

    3
    A graphical representation of a typical electron-positron collision in the Belle II detector. Charged and neutral particles, represented by white arcs and isolated “branches,” respectively, leave signatures in the subdetector systems as they escape from the interaction point. This information is used to reconstruct what occurred during each event, to search for rare and new physics processes.
    Figure credit: KEK/Belle II.

    Belle II’s sensitive detectors, developed in part by PNNL, are able to track all of the energy and particles as they decay. With these detailed measurements and enough collisions, researchers look for rare anomalies—instances when energy “disappears” or can’t be accounted for.

    “There’s more than one thing that could escape invisibly,” said physicist Lynn Wood, PNNL’s project manager for the work at Belle II. “We subtract the invisible things that we know about, then the things that are left could be the outliers that validate theories.”

    A set of theories known as the “Standard Model” predicts known particle interactions with a high degree of accuracy, but particles such as dark matter or the Z prime are not included.

    Standard Model of Particle Physics, Quantum Diaries

    If these new particles exist, theorists predict these outlying incidents will happen at a certain rate. If they are not seen in real data, that could represent a flawed theory, or one where the parameters are not tuned to reality.

    The challenge lies not only in detection but also in the sheer number of collisions researchers need to understand and interpret. Dark matter decays are often proposed to be so rare that even when the accelerator is working at its maximum rate of several billion collisions per day, researchers might see less than one potential dark matter event per day.

    More collisions, more detection

    “The Belle II experiment is a complete upgrade from the first Belle experiment,” said PNNL physicist Bryan Fulsom, who has been involved with electron-positron collider physics for more than a decade. Not only does the upgraded accelerator collide particles at a greater rate to collect more data faster, the researcher-redesigned detectors also handle a higher rate of collisions, endure greater radiation damage, and collect signals faster with more detail.

    Engaging nearly 1000 collaborators from around the globe, the new experiment began in 2018, to embark on a broad program of new particle searches and precision measurements expected to continue for a decade. The Z prime physics publication is the first of several hundred publications that are expected to be produced by the Belle II Collaboration.

    Fulsom cited the “very clean collisions” as the reason Belle II is an ideal experiment to use in the search for particles like the Z prime. When particles collide in Belle II, researchers can measure everything that comes out of the decay and keep track of minute details for an enormous number of collisions.

    3
    The Belle II detector consists of several sensitive purpose-built subdetectors. PNNL was involved with construction of the Particle Identification system, has made past significant computing contributions, and continues to perform data analysis in the experiment.
    Figure credit: KEK/Belle II

    After searching in the small initial Belle II data set, the researchers found no evidence of the proposed Z prime particle. Although they did not immediately discover the Z prime, Belle II will continue to collect orders of magnitude more data for this and other searches.

    Even a non-finding can be good news: ruling out the Z prime particle means that researchers can cross that theory off their list and concentrate their efforts on exploring and validating other predictions. The team at PNNL is currently looking for other ways dark matter may be produced in particle collisions and detected by Belle II.

    “This is a process of elimination,” said Wood. “Theorists make charts of possible explanations, and experiments mark out the regions that we can exclude. Negative results put restrictions on what is possible and let us measure for particles with different parameters.”

    More positives

    Belle II complements other PNNL high-energy physics research in the search for dark matter. This includes long-time partnerships on the Axion Dark Matter Experiment project with the University of Washington.

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


    U Washington ADMX

    PNNL’s expertise in low background dark matter detection also critically contributes to experiments looking for rare dark matter interactions underground by reducing background radiation that can obscure rare signals.

    Ultimately, these and other studies lead to better fundamental understanding to describe the world in which we live in ever greater detail.

    “Calling something dark matter is a broad way to say it’s particles we haven’t detected,” said Fulsom. “We don’t know what it is and where we’ll find it, but projects like Belle II have a wide physics and technology reach beyond dark matter.”

    For example, the detectors developed for dark matter detection and particle physics experiments can have wide-ranging applications in national security, environmental monitoring, and medical imaging. Electronics for these detectors push the limits of design in specialized as well as everyday electronic tools, and the vast amount of data produced in accelerators requires advances in computing and data handling techniques applicable to other areas of big data research.

    And as for dark matter?

    “We’re confident it exists,” said Wood. “Everyone is trying to find out what it is.”

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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