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  • richardmitnick 7:38 pm on September 15, 2022 Permalink | Reply
    Tags: "Researchers at SLAC use purified liquid xenon to search for mysterious dark matter particles", An enormous vat of pure liquid xenon will help scientists at SLAC and around the globe learn more about the universe., , Dark Matter, LUX-ZEPLIN (LZ) experiment at SURF, , ,   

    From The DOE’s SLAC National Accelerator Laboratory: “Researchers at SLAC use purified liquid xenon to search for mysterious dark matter particles” 

    From The DOE’s SLAC National Accelerator Laboratory

    9.15.22
    Kimberly Hickok

    An enormous vat of pure liquid xenon will help scientists at SLAC and around the globe learn more about the universe.

    1
    Xenon purification system at SLAC. The two central columns are each filled with almost half a ton of charcoal, which is used to produce ultra-clean xenon for the LBNL LUX-ZEPLIN (LZ) dark matter experiment. Credit: Jacqueline Ramseyer Orrell/SLAC National Accelerator Laboratory.

    Sitting a mile below ground in an abandoned gold mine in South Dakota is a gigantic cylinder holding 10 tons of purified liquid xenon closely watched by more than 250 scientists around the world. That tank of xenon is the heart of the LBNL LUX-ZEPLIN (LZ) experiment, an effort to detect dark matter – the mysterious invisible substance that makes up 85% of the matter in the universe.

    2
    Diagram of the former Homestake gold mine and laboratory’s spaces nearly a mile underground at SURF.

    “People have been searching for dark matter for over 30 years, and no one has had a convincing detection yet,” said Dan Akerib, professor of particle physics and astrophysics at the Department of Energy’s (DOE) SLAC National Accelerator Laboratory. But with the help of scientists, engineers, and researchers around the globe, Akerib and his colleagues have made the LZ experiment one of the most sensitive particle detectors on the planet.

    To reach that point, SLAC researchers built on their expertise in working with liquid nobles – the liquid forms of noble gases such as xenon – including advancing the technologies used to purify liquid nobles themselves and the systems for detecting rare dark matter interactions within those liquids. And, Akerib said, what researchers have learned will aid not only the search for dark matter, but also other experiments searching for rare particle physics processes.

    “These are really profound mysteries of nature, and this confluence of understanding the very large and very small at the same time is very exciting,” Akerib said. “It’s possible we could learn something completely new about nature.”

    Looking for dark matter deep underground

    A current leading candidate for dark matter is weakly interacting massive particles, or WIMPs. However, as the acronym suggests, WIMPs barely interact with ordinary matter, making them very difficult to detect, despite the fact there are theoretically many of them passing by us all the time.

    To deal with that challenge, the LZ experiment first went deep underground in the former Homestake gold mine, which is now the Sanford Underground Research Facility (SURF) in Lead, South Dakota [above]. There, the experiment is well protected from the constant bombardment of cosmic rays on Earth’s surface – a source of background noise that could make it hard to pick out hard-to-find dark matter.

    Even then, finding dark matter requires a sensitive detector. For that reason, scientists look to noble gases, which are also notoriously reluctant to react with anything. This means there are very few options for what could happen when a dark matter particle, or WIMP, interacts with the atom of a noble gas, and therefore a lower chance of scientists missing an already tough-to-find interaction.

    3
    This animation shows how krypton (red) is removed from xenon gas (blue) by flowing the combined gases through a column of charcoal (black specks). Both elements stick to the charcoal, but krypton is not as strongly attached and gets swept out first when the column is purged with helium gas. (Greg Stewart/SLAC National Accelerator Laboratory)

    But which noble? As it turns out, “xenon is a particularly good noble for detecting dark matter,” Akerib said. Dark matter interacts most strongly with nuclei, and the interaction becomes even stronger with the atomic mass of the atom, Akerib explained. For example, xenon atoms are a little more than three times as heavy as argon atoms, but they’re expected to have interactions with dark matter that are more than ten times as strong.

    Another benefit: “Once you purify other contaminants out of the liquid xenon, it’s going to be very radio quiet by itself,” Akerib said. In other words, the natural radioactive decay of xenon is unlikely to get in the way of detecting the interactions between WIMPs and xenon atoms.

    Just the xenon, please

    The trick, Akerib said, is getting pure xenon, without which all the benefits of the noble gas are moot. However, purified noble gases aren’t readily available – the fact that they don’t interact with much of anything also means they are generally pretty difficult to separate from one another. And, “unfortunately you can’t just buy a purifier off the shelf that will purify noble gases,” Akerib said.

    Akerib and his colleagues at SLAC therefore had to figure out a way to purify all of the liquid xenon they needed for the detector.

    The biggest contaminant in xenon is krypton, which is the next lightest noble gas and has a radioactive isotope, which could mask the interactions researchers are actually looking for. To prevent krypton from becoming the particle detector’s kryptonite, Akerib and his colleagues spent several years perfecting a xenon purifying technique using what’s called gas charcoal chromatography. The basic idea is to separate ingredients in a mixture based on their chemical properties as the mixture is carried through some kind of medium. Gas charcoal chromatography uses helium as the carrier gas for the mixture, and charcoal as the separation medium.

    “You can think of the helium as a steady breeze through the charcoal,” Akerib explained. “Each xenon and krypton atom spends some fraction of time stuck on the charcoal and some time unstuck. When the atoms are in an unstuck state, the helium breeze sweeps them down the column.” Noble gas atoms are less sticky the smaller they are, which means krypton is somewhat less sticky than the xenon, so it gets swept away by the non-sticky helium “breeze,” thus separating the xenon from the krypton. The researchers could then capture the krypton and throw it away and then recover the xenon, Akerib said. “We did that for something like 200 cylinders of xenon gas – it was a pretty large campaign.”

    The LZ experiment isn’t the first experiment SLAC has been involved in an attempt to search for new physics with xenon. The Enriched Xenon Observatory experiment (EXO-200), which ran from 2011 to 2018, isolated a specific xenon isotope to search for a process called neutrinoless double beta decay. Results from the experiment suggested the process is unimaginably rare, but a new proposed search dubbed Next EXO (nEXO) will continue the search using a detector similar to LZ’s.

    A different sort of electrical grid

    No matter what liquid noble fills the detector, a sophisticated detection system is crucial if scientists ever hope to find something like dark matter. Above and below the tower of liquid xenon for the LZ experiment are large, high-voltage grids that create electric fields in the detector. If a dark matter particle collides with a xenon atom and knocks a few electrons off, it will free some electrons from the atom and separately create a burst of light that can be detected by photo detectors, explained Ryan Linehan, a recent PhD graduate from SLAC’s LZ group who helped develop the high voltage grids. Electric fields running through the detector then drive the free electrons up into a thin layer of gas at the top of the cylinder where they create a second light signal. “We can use that second signal together with the original signal to learn a lot of information about position, energy, particle type, and more,” Linehan said.

    But these aren’t your average electrical grids – they’re carrying tens of thousands of volts, so high that any microscopic bits of dust or debris on the wire grid can cause spontaneous reactions that rip electrons out of the wire itself, Linehan said. “And those electrons can create signals that look just like the electrons that came from the xenon,” thus masking the signals they are trying to detect.

    The researchers came up with two main ways to minimize the chances of getting false signals from the grids, Linehan said. First, the team used a chemical process called passivation to remove iron from the surface of the grid wires, leaving a chromium-rich surface that reduces the tendency of the wire to emit electrons. Second, to remove any dust particles, the researchers thoroughly – and very carefully – sprayed the grids with deionized water immediately before installation. “Those processes together helped us get the grids to a state where we could actually get clear data,” he said.

    The LZ team published their first results online in early July, having pushed the search for dark matter farther than it’s ever gone before.

    Linehan and Akerib said they’re impressed by what LZ’s global collaboration has been able to accomplish. “Together, we’re learning something fundamental about the universe and the nature of matter,” Akerib said. “And we’re just getting started.”

    The LZ effort at SLAC is led by Akerib, together with Maria Elena Monzani, a lead scientist at SLAC and LZ deputy operations manager for computing and software, and Thomas Shutt, who was the founding spokesperson of the LZ collaboration.

    The South Dakota Science and Technology Authority, which manages SURF through a cooperative agreement with the U.S. Department of Energy, secured 80% of the xenon in LZ. Funding came from the South Dakota Governor’s office, the South Dakota Community Foundation, the South Dakota State University Foundation, and the University of South Dakota Foundation.

    LZ is supported by the U.S. Department of Energy, Office of Science and the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. LZ is also supported by the U.S. National Science Foundation, the Science & Technology Facilities Council of the United Kingdom, the Portuguese Foundation for Science and Technology, and the Institute for Basic Science, Korea. Over 35 institutions of higher education and advanced research provided support to LZ. The LZ collaboration acknowledges the assistance of the Sanford Underground Research Facility.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    The DOE’s SLAC National Accelerator Laboratory originally named Stanford Linear Accelerator Center, is a Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the Department of Energy Office of Science and located in Menlo Park, California. It is the site of the Stanford Linear Accelerator, a 3.2 kilometer (2-mile) linear accelerator constructed in 1966 and shut down in the 2000s, which could accelerate electrons to energies of 50 GeV.
    Today SLAC research centers on a broad program in atomic and solid-state physics, chemistry, biology, and medicine using X-rays from synchrotron radiation and a free-electron laser as well as experimental and theoretical research in elementary particle physics, astroparticle physics, and cosmology.

    Founded in 1962 as the Stanford Linear Accelerator Center, the facility is located on 172 hectares (426 acres) of Stanford University-owned land on Sand Hill Road in Menlo Park, California—just west of the University’s main campus. The main accelerator is 3.2 kilometers (2 mi) long—the longest linear accelerator in the world—and has been operational since 1966.

    Research at SLAC has produced three Nobel Prizes in Physics

    1976: The charm quark—see J/ψ meson
    1990: Quark structure inside protons and neutrons
    1995: The tau lepton

    SLAC’s meeting facilities also provided a venue for the Homebrew Computer Club and other pioneers of the home computer revolution of the late 1970s and early 1980s.

    In 1984 the laboratory was named an ASME National Historic Engineering Landmark and an IEEE Milestone.

    SLAC developed and, in December 1991, began hosting the first World Wide Web server outside of Europe.

    In the early-to-mid 1990s, the Stanford Linear Collider (SLC) investigated the properties of the Z boson using the Stanford Large Detector [below].

    As of 2005, SLAC employed over 1,000 people, some 150 of whom were physicists with doctorate degrees, and served over 3,000 visiting researchers yearly, operating particle accelerators for high-energy physics and the Stanford Synchrotron Radiation Laboratory (SSRL) [below] for synchrotron light radiation research, which was “indispensable” in the research leading to the 2006 Nobel Prize in Chemistry awarded to Stanford Professor Roger D. Kornberg.

    In October 2008, the Department of Energy announced that the center’s name would be changed to SLAC National Accelerator Laboratory. The reasons given include a better representation of the new direction of the lab and the ability to trademark the laboratory’s name. Stanford University had legally opposed the Department of Energy’s attempt to trademark “Stanford Linear Accelerator Center”.

    In March 2009, it was announced that the SLAC National Accelerator Laboratory was to receive $68.3 million in Recovery Act Funding to be disbursed by Department of Energy’s Office of Science.

    In October 2016, Bits and Watts launched as a collaboration between SLAC and Stanford University to design “better, greener electric grids”. SLAC later pulled out over concerns about an industry partner, the state-owned Chinese electric utility.

    Accelerator

    The main accelerator was an RF linear accelerator that accelerated electrons and positrons up to 50 GeV. At 3.2 km (2.0 mi) long, the accelerator was the longest linear accelerator in the world, and was claimed to be “the world’s most straight object.” until 2017 when the European x-ray free electron laser opened. The main accelerator is buried 9 m (30 ft) below ground and passes underneath Interstate Highway 280. The above-ground klystron gallery atop the beamline, was the longest building in the United States until the LIGO project’s twin interferometers were completed in 1999. It is easily distinguishable from the air and is marked as a visual waypoint on aeronautical charts.

    A portion of the original linear accelerator is now part of the Linac Coherent Light Source [below].

    Stanford Linear Collider

    The Stanford Linear Collider was a linear accelerator that collided electrons and positrons at SLAC. The center of mass energy was about 90 GeV, equal to the mass of the Z boson, which the accelerator was designed to study. Grad student Barrett D. Milliken discovered the first Z event on 12 April 1989 while poring over the previous day’s computer data from the Mark II detector. The bulk of the data was collected by the SLAC Large Detector, which came online in 1991. Although largely overshadowed by the Large Electron–Positron Collider at CERN, which began running in 1989, the highly polarized electron beam at SLC (close to 80%) made certain unique measurements possible, such as parity violation in Z Boson-b quark coupling.


    Presently no beam enters the south and north arcs in the machine, which leads to the Final Focus, therefore this section is mothballed to run beam into the PEP2 section from the beam switchyard.

    The SLAC Large Detector (SLD) was the main detector for the Stanford Linear Collider. It was designed primarily to detect Z bosons produced by the accelerator’s electron-positron collisions. Built in 1991, the SLD operated from 1992 to 1998.

    SLAC National Accelerator Laboratory Large Detector

    PEP

    PEP (Positron-Electron Project) began operation in 1980, with center-of-mass energies up to 29 GeV. At its apex, PEP had five large particle detectors in operation, as well as a sixth smaller detector. About 300 researchers made used of PEP. PEP stopped operating in 1990, and PEP-II began construction in 1994.

    PEP-II

    From 1999 to 2008, the main purpose of the linear accelerator was to inject electrons and positrons into the PEP-II accelerator, an electron-positron collider with a pair of storage rings 2.2 km (1.4 mi) in circumference. PEP-II was host to the BaBar experiment, one of the so-called B-Factory experiments studying charge-parity symmetry.

    SLAC National Accelerator LaboratoryBaBar

    SLAC National Accelerator LaboratorySSRL

    Fermi Gamma-ray Space Telescope

    SLAC plays a primary role in the mission and operation of the Fermi Gamma-ray Space Telescope, launched in August 2008. The principal scientific objectives of this mission are:

    To understand the mechanisms of particle acceleration in AGNs, pulsars, and SNRs.
    To resolve the gamma-ray sky: unidentified sources and diffuse emission.
    To determine the high-energy behavior of gamma-ray bursts and transients.
    To probe dark matter and fundamental physics.

    National Aeronautics and Space AdministrationFermi Large Area Telescope

    National Aeronautics and Space AdministrationFermi Gamma Ray Space Telescope.

    KIPAC


    KIPAC campus

    The Stanford PULSE Institute (PULSE) is a Stanford Independent Laboratory located in the Central Laboratory at SLAC. PULSE was created by Stanford in 2005 to help Stanford faculty and SLAC scientists develop ultrafast x-ray research at LCLS.

    The Linac Coherent Light Source (LCLS)[below] is a free electron laser facility located at SLAC. The LCLS is partially a reconstruction of the last 1/3 of the original linear accelerator at SLAC, and can deliver extremely intense x-ray radiation for research in a number of areas. It achieved first lasing in April 2009.

    The laser produces hard X-rays, 10^9 times the relative brightness of traditional synchrotron sources and is the most powerful x-ray source in the world. LCLS enables a variety of new experiments and provides enhancements for existing experimental methods. Often, x-rays are used to take “snapshots” of objects at the atomic level before obliterating samples. The laser’s wavelength, ranging from 6.2 to 0.13 nm (200 to 9500 electron volts (eV)) is similar to the width of an atom, providing extremely detailed information that was previously unattainable. Additionally, the laser is capable of capturing images with a “shutter speed” measured in femtoseconds, or million-billionths of a second, necessary because the intensity of the beam is often high enough so that the sample explodes on the femtosecond timescale.

    The LCLS-II [below] project is to provide a major upgrade to LCLS by adding two new X-ray laser beams. The new system will utilize the 500 m (1,600 ft) of existing tunnel to add a new superconducting accelerator at 4 GeV and two new sets of undulators that will increase the available energy range of LCLS. The advancement from the discoveries using this new capabilities may include new drugs, next-generation computers, and new materials.

    FACET

    In 2012, the first two-thirds (~2 km) of the original SLAC LINAC were recommissioned for a new user facility, the Facility for Advanced Accelerator Experimental Tests (FACET). This facility was capable of delivering 20 GeV, 3 nC electron (and positron) beams with short bunch lengths and small spot sizes, ideal for beam-driven plasma acceleration studies. The facility ended operations in 2016 for the constructions of LCLS-II which will occupy the first third of the SLAC LINAC. The FACET-II project will re-establish electron and positron beams in the middle third of the LINAC for the continuation of beam-driven plasma acceleration studies in 2019.

    SLAC National Accelerator LaboratoryFACET

    SLAC National Accelerator Laboratory FACET-II upgrading its Facility for Advanced Accelerator Experimental Tests (FACET) – a test bed for new technologies that could revolutionize the way we build particle accelerators.

    The Next Linear Collider Test Accelerator (NLCTA) is a 60-120 MeV high-brightness electron beam linear accelerator used for experiments on advanced beam manipulation and acceleration techniques. It is located at SLAC’s end station B

    SLAC National Accelerator LaboratoryNext Linear Collider Test Accelerator (NLCTA)

    DOE’s SLAC National Accelerator Laboratory campus

    SLAC National Accelerator LaboratoryLCLS

    SLAC National Accelerator LaboratoryLCLS II projected view

    Magnets called undulators stretch roughly 100 meters down a tunnel at SLAC National Accelerator Laboratory, with one side (right) producing hard x-rays and the other soft x-rays.

    SSRL and LCLS are DOE Office of Science user facilities.

     
  • richardmitnick 4:25 pm on September 15, 2022 Permalink | Reply
    Tags: "UR: The Atomic Dark Matter Model:: A Possible Solution to the Shortcomings of CDM", , , , , , Dark Matter   

    From Astrobites : “UR: The Atomic Dark Matter Model:: A Possible Solution to the Shortcomings of CDM” 

    Astrobites bloc

    From Astrobites

    9.15.22
    John Blakely | The Pennsylvania State University

    A significant amount of modern cosmological research has been in the pursuit of understanding dark matter. Dark matter (DM) has long been assumed as the solution to the “missing mass” problem, originating from astrophysicist Fritz Zwicky’s 1933 observations of the Coma Cluster.
    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

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

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


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

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

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

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

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

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

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

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


    __________________________________

    This so-called “dark matter” would not emit any light, or interact with light, but would contain most of the mass of the galaxy cluster. Zwicky discovered that the galaxies in the Coma Cluster [above] were moving too fast to be held together by the gravity of the visible matter in the cluster. Since then, many observations have been made, at a wide range of scales, which all point to the existence of dark matter. Despite this, the physics of the dark matter is still largely not known. A model of dark matter that is able to connect observed data with our understanding of physics is sought after. Though there have been many attempts, none have been able to successfully do this completely.

    The Cold Dark Matter Model: Our Best Guess So Far

    The most popular model held is the Cold Dark Matter paradigm (CDM). CDM provides a satisfyingly simple answer to the “missing mass” in our observations, stating that there is a cold, dark matter component of the universe. Cold means that it is not energetic and is nonrelativistic, and dark means that it only interacts with itself, and baryonic matter, via gravity. However, the scenario, which CDM creates, provides predictions which are in tension with our observations, specifically on smaller scales. A solution to this can either be in the form of a new understanding of the interactions between CDM and the Standard Model, or a new dark matter model which maintains the successes of CDM, but succeeds where CDM fails. A model which could fulfill this is the Atomic Dark Matter Model.

    The Atomic Dark Matter Model: A Possible Solution to the Shortcomings of CDM

    The atomic dark matter model (ADM) consists of a type of matter quite similar to Standard Model atomic and molecular hydrogen. ADM consists of a dark “electron” and “proton” of masses mL and mH, respectively, which interact via a massless dark “photon” at a strength governed by a dark fine structure constant, ɑD. With the model still in its youth, much of the current research in ADM is purposed to whittling down the possible values of mH, mL, and ɑD by restricting them according to our observations and previous theories. In this article we introduce the beginning of how these parameters could be restricted by gravitational wave data.

    In ADM, the dark matter particles are able to form atomic and molecular bound states, analogous to baryonic or ‘regular’ hydrogen, and radiate away some of their initial energy in the form of a dark photon, as well as break these bound states and radiate away energy. This is particularly interesting because the dark halos in ADM, unlike in CDM, can dissipate energy and cool, allowing for some to collapse and form dark compact structures, solving some of CDM’s problems. It’s useful to know which dark halos are able to collapse and form compact structures, like black holes, because it allows us to use gravitational wave data to validate the model and restrict the possible parameter values.

    Which Dark Halos Can Collapse?

    To determine whether a dark halo can collapse, we have to see whether the halo will radiate away the energy it needs to support itself fast enough. To determine this we need to compare the time it takes to collapse under its own gravity to the time it takes to dissipate all of its energy. The free-fall time only depends on the mass density of the halo, but the cooling time depends on the evolution of the number of free and bound dark particles as well as how quickly it can remove its energy. To get the number of free and bound dark particles, we will use what’s known as the ionization fraction, which is just the ratio of how quickly bound states are broken to how quickly they are formed. Once we have this we can compute the volumetric cooling rate, we can get the time it takes to radiate away all of the halos energy. If the halo cools faster than a free-fall time it will collapse, if not then it will remain in hydrostatic equilibrium. This comparison was calculated by Matthew R. Buckley in 2017, and in Figure 1 the solid colored regions show the dark halo masses that can collapse as a function of dark electron mass, mL.

    2
    Figure 1: The solid regions are the results of Matthew R. Buckley in 2017, showing the masses of dark halos that can collapse in collisional ionization equilibrium as a function of dark electron mass (mL), whereas the hatched regions show the halo masses that violate equilibrium as a function of mL. The red and blue regions correspond to a ɑD value of 10^-1 and 10^-2 respectively.

    However, determining whether or not a halo will collapse relies on the dark halo remaining in equilibrium between the rate it forms dark bound states and the rate at which they are broken, but for certain assumptions about the ADM particles this doesn’t hold. If the dark halo violates equilibrium, it doesn’t mean that it won’t collapse, just that it can’t be determined with an ionization fraction dependent on equilibrium.

    To determine the dark halo masses which violate equilibrium over the ADM parameter space as a function of the mass of the dark electron, we have to compare the time it takes for the dark halo to fully ionize versus the time it takes to cool completely. This results in a region of uncertainty in the results of Matthew R. Buckley in 2017, shown in Figure 1 as the hatched regions. Dark halos that fall in these regions will require to be reanalyzed using an ionization fraction that does not rely on equilibrium.

    With this region of indeterminacy defined, finding a simple expression for an ionization fraction which can account for out-of-equilibrium cooling will be much easier. Ultimately, this simpler expression will make tracking the evolution of ADM dark matter much less rigorous and would provide a useful insight into the dynamics of structure formation in the atomic dark sector.

    Special thanks to the STAR undergraduate research program at Penn State for facilitating this project, as well as to James Gurian for advising and teaching the cosmology, physics, and general skills needed for this research.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.

    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 10:29 pm on September 13, 2022 Permalink | Reply
    Tags: "We've made a map of dark matter but still don't know what it is and that's okay", , , Dark Matter,   

    From BBC (UK): “We’ve made a map of dark matter but still don’t know what it is and that’s okay” 

    From BBC (UK)

    9.12.22
    Dr. Katie Mack | The Perimeter Institute for Theoretical Physics (CA)

    1
    © Getty Images

    In early August, astronomers announced that they had created a map of dark matter – the mysterious, invisible stuff that astronomers say underlies all structure in the cosmos – associated with some of the earliest galaxies in the Universe.

    Articles reporting the achievement described the innovative observational technique: searching for tiny distortions of patterns in the cosmic microwave background radiation [CMBR], the backlight of the Universe that originates from the Big Bang.

    These distortions appear because mass bends space, even if that mass belongs to an invisible kind of matter.

    Tellingly though, these reports did not delve into the mystery of what dark matter is, or question whether it even exists. For most astronomers, most of the time, dark matter’s fundamental nature is entirely beside the point.

    Dark matter, whatever it’s made of, is important in our Universe. Studying its distribution helps us understand how galaxies form and helps us discern the entire structure of the cosmos. But are we just fooling ourselves here? Isn’t anyone disturbed by the fact that we can’t see it, and don’t know what it is?

    Despite having never directly detected it, scientists do in fact have very good reasons to believe that dark matter is real. The first story that everyone tells is about how galaxies seem to be rotating at impossible speeds.

    The stars at the outer edges of spiral galaxies are orbiting around the centre so quickly that if there weren’t something providing extra gravity to hold them in, they would have already escaped into intergalactic space, like children flung off a merry-go-round that’s spinning too fast.

    The proposed solution: an invisible, intangible substance, presumably composed of a collection of particles our earthly experiments have all missed, surrounds and penetrates the misbehaving galaxy, and its mass provides the extra gravity the observations require. Every galaxy (with some possible rare exceptions) is embedded in a roughly spherical clump of dark matter we call a “halo”.

    It’s not unreasonable to point to another possibility: maybe we don’t need something new to produce more gravity; maybe gravity just acts differently than we thought. This has been the main approach of dark matter sceptics in astrophysics, and when it comes to galaxy rotation, it seems to be an appealing solution.

    ___________________________________________________
    MOND [Modified Newtonian dynamics]


    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


    ___________________________________________________

    These modified gravity models work so well to solve the rotation problem that news articles appear in papers and magazines regularly proclaiming that dark matter has been disproven by a simple tweak to Newton’s (or Einstein’s) laws.

    But there’s a reason we haven’t all thrown out dark matter and embraced the demise of gravity as we know it: the best evidence for dark matter comes from cosmic phenomena occurring on scales much larger than any galaxy, where there are fewer observational complications and where the agreement with theory is incredibly precise.

    That preponderance of evidence would be compelling even if we completely ignored galaxy rotation, and there has yet to be a modified gravity theory that can compete with dark matter when it comes to everything else: galaxy shapes, galaxy cluster motions, gravitational lensing, elemental abundances from the early universe, the distribution of galaxies on the largest scales, and even the patterns in the cosmic microwave background light itself.

    Even accepting that the astrophysical evidence is strong, it’s understandable to remain uncomfortable with the notion of adding a new particle to the zoo of discovered species without any concrete detection of the particle itself.

    Some of the simplest theoretical possibilities for dark matter’s particle properties have already been ruled out. But rather than give up entirely, astronomers and physicists are constantly searching for new, creative ideas for what dark matter might be and why it hasn’t shown up yet.

    In spite of the experimental no-shows, when all the evidence is taken into account, the idea that the Universe is absolutely overrun by invisible particles just fits the data best.

    There’s an old saying, commonly attributed to statistician George Box, that “all models are wrong, but some are useful.” In cosmology, we sometimes loftily describe our mission as “solving the mysteries of the universe” but in a day-to-day sense, our job is to build and test mathematical models to describe the data we collect.

    Not detecting a particle in a detector might make us uncomfortable, but it doesn’t cancel out any of the ways in which we see dark matter’s influence in the cosmos. And there’s no indication that dark matter ought to be something that interacts with detectors at all.

    It’s still possible some other solution will be found. But whatever it is, it will have to look, observationally, exactly like a collection of invisible, untouchable particles making up most of the matter in the Universe.

    Those of us who spend our time exploring the exciting boundary layer between particle physics and cosmology will keep trying to figure out what this stuff is, really, while astronomers poring over new astrophysical data can make use of what we know about its abundance and behaviour to try to solve other cosmic mysteries.

    And whatever dark matter is, we can be grateful for its role in bringing all that ordinary matter together, and rest assured that it’s likely to continue doing a great job of keeping our Sun from flinging itself off into the void.

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

    Fritz Zwicky.

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

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

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

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

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

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

    Dark Matter Research

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

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

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

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

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

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

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

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

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

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

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    See the full article here .

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  • richardmitnick 9:24 am on September 13, 2022 Permalink | Reply
    Tags: "Why are dark matter halos of ultra-diffuse galaxies so … odd?", A dark matter halo is the halo of invisible matter that permeates and surrounds a galaxy or a cluster of galaxies., , , , Dark Matter, , Questions raised about physicists’ understanding of galaxy formation and the structure of the universe., The distribution of baryons — gas and stars — is much more spread out in ultra-diffuse galaxies compared to “normal” galaxies with similar masses., The distribution of dark matter in these galaxies can be inferred from the motion of gas particles., The ultra-diffuse galaxies rotate more slowly than normal galaxies with similar masses., , , Ultra-diffuse galaxies are so called because of their extremely low luminosity.   

    From The University of California-Riverside And The University of California-Irvine: “Why are dark matter halos of ultra-diffuse galaxies so … odd?” 

    UC Riverside bloc

    From The University of California-Riverside

    And

    UC Irvine bloc

    The University of California-Irvine

    9.12.22
    Iqbal Pittalwala | The University of California-Riverside

    A study co-led by physicists at UC Riverside and UC Irvine has found that dark matter halos of ultra-diffuse galaxies are very odd, raising questions about physicists’ understanding of galaxy formation and the structure of the universe.

    Ultra-diffuse galaxies are so called because of their extremely low luminosity. The distribution of baryons — gas and stars — is much more spread out in ultra-diffuse galaxies compared to “normal” galaxies with similar masses.

    In the following Q&A, Hai-Bo Yu, an associate professor of physics and astronomy at UCR, shares his thoughts on the findings he and UCI’s Manoj Kaplinghat, a long-term collaborator of Yu’s, have published in The Astrophysical Journal [below] about newly discovered ultra-diffuse galaxies and their dark matter halos.

    Yu and Kaplinghat were joined in the research by Demao Kong of Tufts University, and Filippo Fraternali and Pavel E. Mancera Piña of the University of Groningen in the Netherlands. First author Kong will join UCR this fall.

    The research was supported by grants from the National Science Foundation, Department of Energy, John Templeton Foundation, National Aeronautics and Space Administration, Netherlands Research School for Astronomy, and ASTRON, the Netherlands Institute for Radio Astronomy.

    Q. What is a dark matter halo?

    A dark matter halo is the halo of invisible matter that permeates and surrounds a galaxy or a cluster of galaxies. Although dark matter has never been detected in laboratories, physicists are confident dark matter, which makes up 85% of the universe’s matter, exists.

    Q. You’ve found dark matter halos of the ultra-diffuse galaxies are very odd. What is odd about them and what are you comparing them to?

    The ultra-diffuse galaxies we studied are much less massive compared to, say, the Milky Way. They contain a lot of gas, however, and they have much higher gas mass than total stellar mass, which is opposite to what we see in the Milky Way. The ultra-diffuse galaxies also have large sizes.

    The distribution of dark matter in these galaxies can be inferred from the motion of gas particles. What really surprises us is that the presence of baryonic matter itself, predominantly in the form of gas, is nearly sufficient to explain the measured velocity of gas particles and leaves little room for dark matter in the inner regions, where most of the stars and gas are located.

    This is very surprising because in the case of normal galaxies, whose masses are similar to those of the ultra-diffuse galaxies, it’s the opposite: dark matter dominates over baryonic matter. To accommodate this result, we conclude that these dark matter halos must have much lower “concentrations.” That is, they contain much less mass in their inner regions, compared to those of normal galaxies. In this sense, dark matter halos of the ultra-diffuse galaxies are “odd.”

    At first glance, one would expect that such low-concentration halos are so rare that the ultra-diffuse galaxies would not even exist. After looking into the data from state-of-the-art numerical simulations of cosmic structure formation, however, we found the population of low-concentration halos is higher than the expectation.

    Q. What was involved in doing the study?

    This is a collaborative work. Filippo Fraternali and his student Pavel E. Mancera Piña are experts on gas dynamics of galaxies. They discovered that the ultra-diffuse galaxies rotate more slowly than normal galaxies with similar masses. We worked together to interpret measurement data of the gas motion of these galaxies and infer their dark matter distribution. Furthermore, we analyzed data from simulations of cosmic structure formation and identified dark matter halos that have similar properties as those inferred from the ultra-diffuse galaxies.

    Q. Your findings raise questions about our understanding of galaxy formation/structure formation of the universe. How?

    We have many questions regarding the formation and evolution of these newly discovered galaxies. For example, the ultra-diffuse galaxies contain a lot of gas and we do not know how this gas is retained during galaxy formation. Further, our results indicate that these galaxies may be younger than normal galaxies. The formation of the ultra-diffuse galaxies is not well understood, and more work is needed.

    Q. What makes ultra-diffuse galaxies so interesting?

    These are amazing objects to study because of their surprising properties, as discussed in our work. The newly discovered ultra-diffuse galaxies provide a new window for further testing our understanding of galaxy formation, probably even the nature of dark matter.

    Science paper:
    The Astrophysical Journal

    See the full article here .

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    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.

    University of California-Riverside Campus

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

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

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

    History

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

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

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

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

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

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

    Academics

    As a campus of The University of California system, The University of California-Riverside is governed by a Board of Regents and administered by a president University of California-Riverside ‘s academic policies are set by its Academic Senate, a legislative body composed of all UC-Riverside faculty members.

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

    Research and economic impact

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

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

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

     
  • richardmitnick 10:55 am on September 8, 2022 Permalink | Reply
    Tags: "University of Toronto Astro September Grad Student of the Month: Harrison Winch", , , , , , Dark Matter,   

    From The University of Toronto Dunlap Institute for Astronomy and Astrophysics (CA) : “University of Toronto Astro September Grad Student of the Month: Harrison Winch” 

    From The University of Toronto Dunlap Institute for Astronomy and Astrophysics (CA)

    At

    The University of Toronto (CA)

    9.6.22

    1
    Credit: Harrison Winch.
    Harrison is starting his fifth year as a PhD student at the University of Toronto’s David A. Dunlap Department of Astronomy & Astrophysics, specializing in theoretical cosmology and dark matter research.

    Harrison grew up in Toronto, and graduated from the interdisciplinary Arts & Sciences program at McMaster University with a Combined Honours degree in Physics and a minor in Mathematics.

    How did you first become interested in Astronomy and Astrophysics?

    As a child, I was always fascinated with the night sky, particularly on camping trips in Algonquin Park where I could get away from the bright lights of Toronto. I remember seeing the Andromeda Galaxy through binoculars for the first time, and being blown away by the sheer sizes and scales involved. I started to seriously consider a career in astrophysics after I participated in the Summer Undergraduate Research Program at CITA here at U of T during the summer of 2016, and I’ve been hooked on theoretical cosmology ever since.

    Can you tell us a little bit about your specific field of research?

    Most of my research focuses on a theoretical type of Dark Matter called the Axion.

    2
    Axions can be thought of as a bunch of pendulums oscillating everywhere in space. How close the pendulums start to the very top determines how spread out they become. Credit: Harrison Winch.

    3
    Axions with high starting angles are clumpier on small scales, while axions with low starting angles are less clumpy on small scales. Credit: Harrison Winch.

    4
    This image shows what the universe would look like if we could see all the dark matter. Credit: NASA.

    Dark Matter is a mysterious invisible substance that we find everywhere in space, but we currently have no clue what it is made of. One possible candidate is the Axion, which is a broad class of hypothetical ultralight particles that could make up some, or all, of the Dark Matter we find in our universe. I write software that simulates what these Axion particles might have been doing long ago during the Big Bang, when everything in the universe was crammed close together at high energies. I am trying to predict whether the high-energy properties of these Axions during the Big Bang might leave an observable signature on our universe today. If we know what kind of observable signatures to look for, we can start to narrow down what kind of Axions might or might not contribute to the Dark Matter we find in our universe.

    What’s the most exciting thing about your research?

    The aspect of my research that I find most exciting is how creative and speculative it is. Much like how the author of a fantasy or sci-fi novel gets to explore how a hypothetical character would react and evolve in extreme and dangerous situations, so too do I get to explore how these hypothetical particles would behave and evolve in similarly extreme situations that no one has ever imagined before. We are exploring new ground conceptually, which is already very exciting, but at the end of the day the goal is to calculate observable predictions that can be compared to the universe we live in. The possibility of these tangible results and real predictions makes the speculative parts of my research even more exciting.

    What do you hope will be your next step, professionally?

    When I’m not writing axion software, I am also part of the Simons Observatory collaboration, which is working on building a new cosmology telescope in the next couple of years. By the time I graduate, the telescope will be starting to make observations of the early universe, and these observations have the potential to shed new light on the Axion models I am exploring. After I graduate, I would love to use this new data from the Simons Observatory to actually search for the observable signatures that I am currently predicting, and perhaps either confirm or rule out these hypothetical Axion models.In the longer term, I am very passionate about science communication and teaching, and I would love to be able to teach physics or astronomy at a post-secondary level. I love finding new ways to communicate these complex and always-evolving ideas, and help to share my excitement and enthusiasm about them!

    See the full article here .


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    Dunlap Institute campus

    The Dunlap Institute for Astronomy & Astrophysics (CA) at the University of Toronto (CA) is an endowed research institute with nearly 70 faculty, postdocs, students and staff, dedicated to innovative technology, ground-breaking research, world-class training, and public engagement. The research themes of its faculty and Dunlap Fellows span the Universe and include: optical, infrared and radio instrumentation; Dark Energy; large-scale structure; the Cosmic Microwave Background; the interstellar medium; galaxy evolution; cosmic magnetism; and time-domain science.

    The Dunlap Institute (CA), Department of Astronomy & Astrophysics (CA), Canadian Institute for Theoretical Astrophysics (CA), and Centre for Planetary Sciences (CA) comprise the leading centre for astronomical research in Canada, at the leading research university in the country, the University of Toronto (CA).

    The Dunlap Institute (CA) is committed to making its science, training and public outreach activities productive and enjoyable for everyone, regardless of gender, sexual orientation, disability, physical appearance, body size, race, nationality or religion.

    Our work is greatly enhanced through collaborations with the Department of Astronomy & Astrophysics (CA), Canadian Institute for Theoretical Astrophysics (CA), David Dunlap Observatory (CA), Ontario Science Centre (CA), Royal Astronomical Society of Canada (CA), the Toronto Public Library (CA), and many other partners.

    The University of Toronto participates in the CHIME Canadian Hydrogen Intensity Mapping Experiment at The Canada NRCC Dominion Radio Astrophysical Observatory in Penticton, British Columbia(CA) Altitude 545 m (1,788 ft).


    The The University of Toronto(CA) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen’s Park. It was founded by royal charter in 1827 as King’s College, the oldest university in the province of Ontario.

    Originally controlled by the Church of England, the university assumed its present name in 1850 upon becoming a secular institution.

    As a collegiate university, it comprises eleven colleges each with substantial autonomy on financial and institutional affairs and significant differences in character and history. The university also operates two satellite campuses located in Scarborough and Mississauga.

    The University of Toronto has evolved into Canada’s leading institution of learning, discovery and knowledge creation. We are proud to be one of the world’s top research-intensive universities, driven to invent and innovate.

    Our students have the opportunity to learn from and work with preeminent thought leaders through our multidisciplinary network of teaching and research faculty, alumni and partners.

    The ideas, innovations and actions of more than 560,000 graduates continue to have a positive impact on the world.

    Academically, The University of Toronto is noted for movements and curricula in literary criticism and communication theory, known collectively as the Toronto School.

    The university was the birthplace of insulin and stem cell research, and was the site of the first electron microscope in North America; the identification of the first black hole Cygnus X-1; multi-touch technology, and the development of the theory of NP-completeness.

    The university was one of several universities involved in early research of deep learning. It receives the most annual scientific research funding of any Canadian university and is one of two members of the Association of American Universities outside the United States, the other being McGill University [Université McGill] (CA) .

    The Varsity Blues are the athletic teams that represent the university in intercollegiate league matches, with ties to gridiron football, rowing and ice hockey. The earliest recorded instance of gridiron football occurred at University of Toronto’s University College in November 1861.

    The university’s Hart House is an early example of the North American student centre, simultaneously serving cultural, intellectual, and recreational interests within its large Gothic-revival complex.

    The University of Toronto has educated three Governors General of Canada, four Prime Ministers of Canada, three foreign leaders, and fourteen Justices of the Supreme Court. As of March 2019, ten Nobel laureates, five Turing Award winners, 94 Rhodes Scholars, and one Fields Medalist have been affiliated with the university.

    Early history

    The founding of a colonial college had long been the desire of John Graves Simcoe, the first Lieutenant-Governor of Upper Canada and founder of York, the colonial capital. As an University of Oxford (UK)-educated military commander who had fought in the American Revolutionary War, Simcoe believed a college was needed to counter the spread of republicanism from the United States. The Upper Canada Executive Committee recommended in 1798 that a college be established in York.

    On March 15, 1827, a royal charter was formally issued by King George IV, proclaiming “from this time one College, with the style and privileges of a University … for the education of youth in the principles of the Christian Religion, and for their instruction in the various branches of Science and Literature … to continue for ever, to be called King’s College.” The granting of the charter was largely the result of intense lobbying by John Strachan, the influential Anglican Bishop of Toronto who took office as the college’s first president. The original three-storey Greek Revival school building was built on the present site of Queen’s Park.

    Under Strachan’s stewardship, King’s College was a religious institution closely aligned with the Church of England and the British colonial elite, known as the Family Compact. Reformist politicians opposed the clergy’s control over colonial institutions and fought to have the college secularized. In 1849, after a lengthy and heated debate, the newly elected responsible government of the Province of Canada voted to rename King’s College as the University of Toronto and severed the school’s ties with the church. Having anticipated this decision, the enraged Strachan had resigned a year earlier to open Trinity College as a private Anglican seminary. University College was created as the nondenominational teaching branch of the University of Toronto. During the American Civil War the threat of Union blockade on British North America prompted the creation of the University Rifle Corps which saw battle in resisting the Fenian raids on the Niagara border in 1866. The Corps was part of the Reserve Militia lead by Professor Henry Croft.

    Established in 1878, the School of Practical Science was the precursor to the Faculty of Applied Science and Engineering which has been nicknamed Skule since its earliest days. While the Faculty of Medicine opened in 1843 medical teaching was conducted by proprietary schools from 1853 until 1887 when the faculty absorbed the Toronto School of Medicine. Meanwhile the university continued to set examinations and confer medical degrees. The university opened the Faculty of Law in 1887, followed by the Faculty of Dentistry in 1888 when the Royal College of Dental Surgeons became an affiliate. Women were first admitted to the university in 1884.

    A devastating fire in 1890 gutted the interior of University College and destroyed 33,000 volumes from the library but the university restored the building and replenished its library within two years. Over the next two decades a collegiate system took shape as the university arranged federation with several ecclesiastical colleges including Strachan’s Trinity College in 1904. The university operated the Royal Conservatory of Music from 1896 to 1991 and the Royal Ontario Museum from 1912 to 1968; both still retain close ties with the university as independent institutions. The University of Toronto Press was founded in 1901 as Canada’s first academic publishing house. The Faculty of Forestry founded in 1907 with Bernhard Fernow as dean was Canada’s first university faculty devoted to forest science. In 1910, the Faculty of Education opened its laboratory school, the University of Toronto Schools.

    World wars and post-war years

    The First and Second World Wars curtailed some university activities as undergraduate and graduate men eagerly enlisted. Intercollegiate athletic competitions and the Hart House Debates were suspended although exhibition and interfaculty games were still held. The David Dunlap Observatory in Richmond Hill opened in 1935 followed by the University of Toronto Institute for Aerospace Studies in 1949. The university opened satellite campuses in Scarborough in 1964 and in Mississauga in 1967. The university’s former affiliated schools at the Ontario Agricultural College and Glendon Hall became fully independent of the University of Toronto and became part of University of Guelph (CA) in 1964 and York University (CA) in 1965 respectively. Beginning in the 1980s reductions in government funding prompted more rigorous fundraising efforts.

    Since 2000

    In 2000 Kin-Yip Chun was reinstated as a professor of the university after he launched an unsuccessful lawsuit against the university alleging racial discrimination. In 2017 a human rights application was filed against the University by one of its students for allegedly delaying the investigation of sexual assault and being dismissive of their concerns. In 2018 the university cleared one of its professors of allegations of discrimination and antisemitism in an internal investigation after a complaint was filed by one of its students.

    The University of Toronto was the first Canadian university to amass a financial endowment greater than c. $1 billion in 2007. On September 24, 2020 the university announced a $250 million gift to the Faculty of Medicine from businessman and philanthropist James C. Temerty- the largest single philanthropic donation in Canadian history. This broke the previous record for the school set in 2019 when Gerry Schwartz and Heather Reisman jointly donated $100 million for the creation of a 750,000-square foot innovation and artificial intelligence centre.

    Research

    Since 1926 the University of Toronto has been a member of the Association of American Universities a consortium of the leading North American research universities. The university manages by far the largest annual research budget of any university in Canada with sponsored direct-cost expenditures of $878 million in 2010. In 2018 the University of Toronto was named the top research university in Canada by Research Infosource with a sponsored research income (external sources of funding) of $1,147.584 million in 2017. In the same year the university’s faculty averaged a sponsored research income of $428,200 while graduate students averaged a sponsored research income of $63,700. The federal government was the largest source of funding with grants from the Canadian Institutes of Health Research; the Natural Sciences and Engineering Research Council; and the Social Sciences and Humanities Research Council amounting to about one-third of the research budget. About eight percent of research funding came from corporations- mostly in the healthcare industry.

    The first practical electron microscope was built by the physics department in 1938. During World War II the university developed the G-suit- a life-saving garment worn by Allied fighter plane pilots later adopted for use by astronauts.Development of the infrared chemiluminescence technique improved analyses of energy behaviours in chemical reactions. In 1963 the asteroid 2104 Toronto was discovered in the David Dunlap Observatory (CA) in Richmond Hill and is named after the university. In 1972 studies on Cygnus X-1 led to the publication of the first observational evidence proving the existence of black holes. Toronto astronomers have also discovered the Uranian moons of Caliban and Sycorax; the dwarf galaxies of Andromeda I, II and III; and the supernova SN 1987A. A pioneer in computing technology the university designed and built UTEC- one of the world’s first operational computers- and later purchased Ferut- the second commercial computer after UNIVAC I. Multi-touch technology was developed at Toronto with applications ranging from handheld devices to collaboration walls. The AeroVelo Atlas which won the Igor I. Sikorsky Human Powered Helicopter Competition in 2013 was developed by the university’s team of students and graduates and was tested in Vaughan.

    The discovery of insulin at The University of Toronto in 1921 is considered among the most significant events in the history of medicine. The stem cell was discovered at the university in 1963 forming the basis for bone marrow transplantation and all subsequent research on adult and embryonic stem cells. This was the first of many findings at Toronto relating to stem cells including the identification of pancreatic and retinal stem cells. The cancer stem cell was first identified in 1997 by Toronto researchers who have since found stem cell associations in leukemia; brain tumors; and colorectal cancer. Medical inventions developed at Toronto include the glycaemic index; the infant cereal Pablum; the use of protective hypothermia in open heart surgery; and the first artificial cardiac pacemaker. The first successful single-lung transplant was performed at Toronto in 1981 followed by the first nerve transplant in 1988; and the first double-lung transplant in 1989. Researchers identified the maturation promoting factor that regulates cell division and discovered the T-cell receptor which triggers responses of the immune system. The university is credited with isolating the genes that cause Fanconi anemia; cystic fibrosis; and early-onset Alzheimer’s disease among numerous other diseases. Between 1914 and 1972 the university operated the Connaught Medical Research Laboratories- now part of the pharmaceutical corporation Sanofi-Aventis. Among the research conducted at the laboratory was the development of gel electrophoresis.

    The University of Toronto is the primary research presence that supports one of the world’s largest concentrations of biotechnology firms. More than 5,000 principal investigators reside within 2 kilometres (1.2 mi) from the university grounds in Toronto’s Discovery District conducting $1 billion of medical research annually. MaRS Discovery District is a research park that serves commercial enterprises and the university’s technology transfer ventures. In 2008, the university disclosed 159 inventions and had 114 active start-up companies. Its SciNet Consortium operates the most powerful supercomputer in Canada.

     
  • richardmitnick 11:36 am on August 22, 2022 Permalink | Reply
    Tags: "Genius lair: Australia’s dark matter experiment underfoot", "Underground ‘genius lab’ one step closer to finding dark matter", , , DAMA LIBRA Dark Matter Experiment 1.5 km beneath Italy’s Gran Sasso mountain located in the Abruzzo region of central Italy., Dark Matter, , The Australian Nuclear Science and Technology Organisation (ANSTO)(AU), The Stawell Underground Physics Laboratory 1km underground.,   

    From The University of Melbourne (AU) Via “COSMOS (AU)” : “Underground ‘genius lab’ one step closer to finding dark matter” 

    u-melbourne-bloc

    From The University of Melbourne (AU)

    Via

    Cosmos Magazine bloc

    “COSMOS (AU)”

    8.19.22
    Jacinta Bowler

    A black (mine) hole in central Victoria ready to swallow up the equipment…

    1
    The Stawell Underground Physics Laboratory 1km underground. Credit Olivia Gumienny/University of Melbourne.

    An experiment to search for dark matter, which will take place in a gold mine under the Victorian town of Stawell, has just completed the first stage of its plans.

    Stage one of the Stawell Underground Physics Laboratory (SUPL) was officially opened today. Although there’s no detector or other equipment yet in the new space, the once cave like structure now looks like a shiny new laboratory, equipped with working showers and air-conditioning.

    The lab, located in the active Stawell Gold Mine, is 1-kilometre underground and includes a research hall 33 metres long, 10 metres wide and 12.3 metres high.

    “We know there is much more matter in the universe than we can see,” says Professor Elisabetta Barberio from the University of Melbourne.

    “With the Stawell Underground Physics Laboratory, we have the tools and location to detect this dark matter. Proving the existence of dark matter will help us understand its nature and forever change how we see the universe.”

    The lab has now been handed over to the Stawell Underground Physics Laboratory team who will start bringing in equipment in the next month.

    This may take a while, as the detector is housed in tonnes of steel that need to be brought down the long, winding tunnel in the mine itself.

    The experiment has been marred by delays. The original project was set to be finished in the mid-2010s, and even last year there were hopes of getting it finished by the end of 2021.

    However, with the lab finally complete, it hopefully won’t be too long until they start trying to detect the mysterious particles which seem to make up our Universe.

    Also from “COSMOS (AU)”

    “Genius lair: Australia’s dark matter experiment underfoot”

    8.20.21
    Jacinta Bowler

    2
    Photo credit: The ARC Centre of Excellence for Dark Matter Particle

    Deep in a gold mine on the outskirts of the small Victorian country town of Stawell, several hours’ drive to the north-west of Melbourne, a lab is being built to find one of the universe’s most elusive substances: dark matter.

    The lab, located a kilometre underground, currently looks more like a tennis-court sized cave than a multi-million-dollar operation. That’s because the lab – a partnership between the University of Melbourne, ANSTO, Swinburne and more – is still very much a work in progress. But if successful in its quest it could help solve one of the greatest mysteries of astrophysics.

    “It’s crunch time for us,” says University of Melbourne Associate Professor Phillip Urquijo, a particle physicist and a technical coordinator of the dark matter experiment, called SABRE – the Sodium Iodide with Active Background Rejection Experiment.

    “The lab itself should be completed by December. We’re hoping by November we can start bringing in some of our experimental equipment.”

    For something that is thought to make up 85% of the matter in the universe, dark matter hasn’t been easy to find. It can’t be seen in any of the wavelengths that would normally be used to detect space stuff like gas and dust. In fact, it doesn’t seem to interact with electromagnetic force at all – meaning it doesn’t absorb, reflect or emit any type of light.

    Scientists only know it exists because stars, galaxies and galaxy clusters have way too much gravitational pull without some further explanation, such as a bunch of dark matter hiding somewhere.

    “If we manage to find it, that’s a guaranteed Nobel Prize,” says ANSTO strategic projects senior advisor Dr Richard Garrett. “It’s like [gravitational] waves. That’s another thing they were looking for for 30 to 40 years until, finally, these enormous experiments (namely, the Laser Interferometer Gravitational-Wave Observatory) found it.”

    But the search to detect dark matter has so far been lacklustre. Until now.

    Underneath our noses

    There’s a couple of different ways researchers have been trying to detect dark matter on Earth.

    The first attempts to catch dark matter decaying into something we can detect, like gamma rays or particle-antiparticle pairs. Unfortunately, dark matter isn’t the only astronomical process that produces these, adding another layer of difficulty to the process.

    Then there are detectors like SABRE, which try to detect the recoil of a type of hypothetical dark matter particle – called weakly interacting massive particles, or WIMPS – off targets deep underground.

    3
    Cutaway view of a 3D rendering of SABRE. Credit: Michael Mews (The University of Melbourne, SABRE member)

    But every single detector built has so far only been able to find signals that could be attributed to another cause. Dark matter has stayed obscured.

    With one exception. For the last 25 years, a detector called DAMA/LIBRA under the Laboratori Nazionali del Gran Sasso, near L’Aquila central-eastern Italy, has been noting a yearly pattern in the number of signals they capture. Called an “annual modulation effect”, the team believe it could be due to Earth moving closer to and further away from our galaxy’s dark matter halo.

    “Over those 25 years, the data [at DAMA/LIBRA] showed that it has this annual modulation effect with extremely, extremely high levels of significance,” says Urquijo. “Through their studies, and through independent reviews of their studies, they couldn’t rule out a dark matter hypothesis to explain it.”

    The Italian lab has been something of a black sheep of the detector world, as no other detector has been able to replicate their results. One reason for this is due to the particular sodium iodide crystals the DAMA/LIBRA team has used. They were the most radio pure – meaning very low levels of radioactivity – ever made, a record that the team still holds to this day.

    The crystals are made by starting with “astrograde” sodium iodide powder – a compound that’s low in radioactivity but not yet a crystal. When researchers grow the crystal from the powder, normally radioactive contaminants from the environment end up tangled in the crystals, and so very specific machinery is needed to grow and refine it while keeping radioactivity low.

    “It’s actually a very difficult and time-consuming R&D process that is very, very niche,” says Urquijo about the crystals.

    But sceptics of DAMA/LIBRA don’t think it’s to do with the radio purity of the crystals. Because the pattern is detected annually, they propose that the detector is only measuring this variation in signal due to the changing seasons.

    That’s where being on the other side of the world with opposite seasons comes in handy.

    “If we see the same effect as theirs, we know it’s not a seasonal effect, it’s something external,” says Urquijo. “We’ll both be seeing dark matter, essentially.”

    Trying different rocks

    Even if it’s not dark matter, it would still be something external to the Earth that scientists don’t know about yet, which would be almost as fascinating as finding dark matter.

    But first they have to finish the detector.

    So far, they’ve made sodium iodide crystals even more radio pure than the ones in the DAMA/LIBRA experiment – a feat that took a long research and development process between institutions around the world.

    The Australian Nuclear Science and Technology Organisation, (ANSTO)(AU) already had facilities set up to test minute levels of radiation and the team are testing all their materials for radioactivity, making sure everything is as low as possible. Small levels of radiation exist all around us – even bananas and human beings, for example, are both a little radioactive. So the team must limit this “normal” radioactivity so that it doesn’t interfere with the detector.

    “We’ve been measuring all kinds of sands and gravels and cement powders from all over Australia, trying to find the best concrete mix for the construction,” says Garrett.

    “We’re [deep underground] looking for very, very weak signals, but there’s no point doing that if the concrete we use is radioactive.”

    Then there’s the location. Working in an active gold mine has many positives. The mining company takes care of all the ventilation and safety management. Plus, the mine workers can transport the scientists in specially designed mine cars through the long winding tunnels all the way down to the lab.

    But it has its drawbacks and challenges. The construction of the lab was delayed for almost three years when the mine changed owners and shut down for a while. Plus, the cave has to be vacated every eight hours so the miners can blast for gold.

    Diagrams show the SABRE instrument looking a bit like a chandelier inside a vat, encased in a metal vault. The detector itself is the chandelier, hanging down from the top of the vat and filled with 50kg of the radio-pure sodium iodide crystals to detect any tiny hints of radiation.

    The vat, which the team call the Veto, is lined with photomultiplier detectors (incredibly sensitive light detectors) dotted throughout, and will be containing linear alkylbenzene – a liquid normally used to make detergent, but in this case used as a “liquid scintillator” that will flash with light when hit with radiation. And then there’s the four-metre-tall vault, which even Urquijo might tell you is a little over the top: SABRE will have something in the region of 100 tonnes of steel shielding the experiment from stray particle radiation that would pollute any potential measurements.

    “We were really paranoid about background radiation,” Urquijo explains. “The region of lowest radioactivity you’ll find anywhere in the Southern Hemisphere is right in the middle of those crystals.

    “We have to be better because we’re coming second.”

    But right now, the detector parts have not yet been moved into the mine – instead, some of this dark matter-finding machinery is sitting in a car park.

    “Melbourne Uni doesn’t have a lot of space to store equipment so we’re using our link through ANSTO to just sit [the liquid scintillator] at the car park there,” says Urquijo.

    Once the detector is finally set up, there won’t be much to do but sit up on the surface and wait for results. But until then, there’s plenty to keep the team busy.

    “Every material comes in and we measure it for radioactivity to see if it’s good enough,” says Garrett.

    “It’s a race against time.”

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

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

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

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

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

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

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

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

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

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

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

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

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

    3
    The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
    __________________________________

    See the full article here .


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

    Stem Education Coalition

    u-melbourne-campus

    The University of Melbourne (AU) is an Australian public research university located in Melbourne, Victoria. Founded in 1853, it is Australia’s second oldest university and the oldest in Victoria. Times Higher Education ranks Melbourne as 33rd in the world, while the Academic Ranking of World Universities places Melbourne 44th in the world (both first in Australia).

    Melbourne’s main campus is located in Parkville, an inner suburb north of the Melbourne central business district, with several other campuses located across Victoria. Melbourne is a sandstone university and a member of the Group of Eight, Universitas 21 and the Association of Pacific Rim Universities. Since 1872 various residential colleges have become affiliated with the university. There are 12 colleges located on the main campus and in nearby suburbs offering academic, sporting and cultural programs alongside accommodation for Melbourne students and faculty.

    Melbourne comprises 11 separate academic units and is associated with numerous institutes and research centres, including the Walter and Eliza Hall Institute of Medical Research, Florey Institute of Neuroscience and Mental Health, the Melbourne Institute of Applied Economic and Social Research and the Grattan Institute. Amongst Melbourne’s 15 graduate schools the Melbourne Business School, the Melbourne Law School and the Melbourne Medical School are particularly well regarded.

    Four Australian prime ministers and five governors-general have graduated from Melbourne. Nine Nobel laureates have been students or faculty, the most of any Australian university.

     
  • richardmitnick 11:31 am on July 23, 2022 Permalink | Reply
    Tags: "A quantum sense for dark matter", , Astrophysical evidence for dark matter has accreted for decades., , , , Center on Quantum Sensing and Quantum Materials at the University of Illinois - Urbana-Champaign, , , Dark Matter, , Dark Matter Radio (DM Radio), DM Radio consists of a radio circuit containing a charge-storing capacitor and a current-storing inductor., , In a strong magnetic field an axion should sometimes turn into a radio photon whose frequency depends on the axion’s mass., In the 1980s theorists hypothesized what soon became the leading contender: weakly interacting massive particles (WIMPs)., Instead of one type of particle dark matter might even consist of a hidden “dark sector” of multiple new particles that would interact through gravity but not the three other forces., Just as photons convey the electromagnetic force dark photons might convey a dark electromagnetic force., , , , , , Quantum sensors open the way to testing new ideas for what dark matter might be., , The interest in quantum sensors also reflects the tinkerer culture of dark matter hunters., The second most popular candidate—and one DM Radio targets—is the axion., The trick is to find a semiconductor sensitive to very low-energy photons., To spot such quarry dark matter hunters have turned to quantum sensors—a shift partly inspired by another hot field: quantum computing.,   

    From “Science Magazine” : “A quantum sense for dark matter” 

    From “Science Magazine”

    28 Apr 2022
    Adrian Cho

    Bullet Cluster NASA Chandra NASA ESA Hubble, evidence of shock.


    A collision of galaxy clusters separated gas (pink) from dark matter (blue), mapped from subtle gravitational distortions in the images of background galaxies. Credits:(X-ray) NASA/CXC/CFA/M. Markevitch et al.; (Optical) D. Clowe et al. NASA/STSCI; Magellan/U. Arizona/; (Lensing Map) D. Clowe et al./NASA/STSCI; ESO WFI; Magellan/U. Arizona/

    Kent Irwin has a vision: He aims to build a glorified radio that will reveal the nature of Dark Matter, the invisible stuff that makes up 85% of all matter. For decades, physicists have struggled to figure out what the stuff is, stalking one hypothetical particle after another, only to come up empty. However, if Dark Matter consists of certain nearly massless particles, then in the right setting it might generate faint, unquenchable radio waves. Irwin, a quantum physicist at Stanford University, plans to tune in to that signal in an experiment called Dark Matter Radio (DM Radio).

    No ordinary radio will do. To make the experiment practical, Irwin’s team plans to transform it into a quantum sensor—one that exploits the strange rules of quantum mechanics. Quantum sensors are a hot topic, having received $1.275 billion in funding in the 2018 U.S. National Quantum Initiative. Some scientists are employing them as microscopes and gravimeters. But because of the devices’ unparalleled sensitivity, Irwin says, “dark matter is a killer app for quantum sensing.”

    DM Radio is just one of many new efforts to use quantum sensors to hunt the stuff. Some approaches detect the granularity of the subatomic realm, in which matter and energy come in tiny packets called quanta. Others exploit the trade-offs implicit in the famous Heisenberg uncertainty principle. Still others borrow technologies being developed for quantum computing. Physicists don’t agree on the definition of a quantum sensor, and none of the concepts is entirely new. “I would argue that quantum sensing has been happening in one form or another for a century,” says Peter Abbamonte, a condensed matter physicist and leader of the Center on Quantum Sensing and Quantum Materials at the University of Illinois – Urbana-Champaign (UIUC).

    Still, Yonatan Kahn, a theoretical physicist at UIUC, says quantum sensors open the way to testing new ideas for what Dark Matter might be. “You shouldn’t just go blindly looking” for Dark Matter, Kahn says. “But even if your model is made of bubblegum and paperclips, if it satisfies all cosmological constraints, it’s fair game.” Quantum sensing is essential for testing many of those models, Irwin says. “It can make it possible to do an experiment in 3 years that would otherwise take thousands of years.”

    Astrophysical evidence for Dark Matter has accreted for decades. For example, the stars in spiral galaxies appear to whirl so fast that their own gravity shouldn’t keep them from flying into space. The observation implies that the stars circulate within a vast cloud of Dark Matter that provides the additional gravity needed to rein them in. Physicists assume it consists of swarms of some as-yet-unknown fundamental particle.

    In the 1980s theorists hypothesized what soon became the leading contender: weakly interacting massive particles (WIMPs). Emerging in the hot soup of particles after the big bang, WIMPs would interact with ordinary matter only through gravity and the weak nuclear force, which produces a kind of radioactive decay. Like the particles that convey the weak force, the W and Z bosons, WIMPs would weigh roughly 100 times as much as a proton. And just enough WIMPs would naturally linger—a few thousand per cubic meter near Earth—to account for Dark Matter.

    Occasionally a WIMP should crash into an atomic nucleus and blast it out of its atom. So, to spot WIMPs, experimenters need only look for recoiling nuclei in detectors built deep underground to protect them from extraneous radiation. But no signs of WIMPs have appeared, even as detectors have grown bigger and more sensitive. Fifteen years ago, WIMP detectors weighed kilograms; now, the biggest contain several tons of frigid liquid xenon.

    The second most popular candidate—and one DM Radio targets—is the axion. Far lighter than WIMPs, axions are predicted by a theory that explains a certain symmetry of the strong nuclear force, which binds quarks into trios to make protons and neutrons. Axions would also emerge in the early universe, and theorists originally estimated they could account for Dark Matter if the axion has a mass between one-quadrillionth and 100-quadrillionths of a proton.

    In a strong magnetic field an axion should sometimes turn into a radio photon whose frequency depends on the axion’s mass. To amplify the faint signal, physicists place in the field an ultracold cylindrical metal cavity designed to resonate with radio waves just as an organ pipe rings with sound. The Axion Dark Matter Experiment (ADMX) at the University of Washington, Seattle, scans the low end of the mass range, and an experiment called the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC) at Yale University probes the high end. But no axions have shown up yet.

    In recent years physicists have begun to consider other possibilities. Maybe axions are either more or less massive than previously estimated. Instead of one type of particle Dark Matter might even consist of a hidden “dark sector” of multiple new particles that would interact through gravity but not the three other forces, electromagnetism and the weak and strong nuclear forces. Rather, they would have their own forces, says Kathryn Zurek, a theorist at the California Institute of Technology. So, just as photons convey the electromagnetic force dark photons might convey a dark electromagnetic force. Dark and ordinary electromagnetism might intertwine so that rarely, a dark photon could morph into an ordinary one.

    To spot such quarry Dark Matter hunters have turned to quantum sensors—a shift partly inspired by another hot field: quantum computing. A quantum computer flips quantum bits, or qubits, that can be set to 0, 1, or, thanks to the odd rules of quantum mechanics, 0 and 1 at the same time. That may seem irrelevant to hunting dark matter, but such qubits must be carefully controlled and shielded from external interference, exactly what Dark Matter hunters already do with their detectors, says Aaron Chou, a physicist at Fermi National Accelerator Laboratory (Fermilab) who works on ADMX. “We have to keep these devices very, very well isolated from the environment so that when we see the very, very rare event, we’re more confident that it might be due to the Dark Matter.”

    The interest in quantum sensors also reflects the tinkerer culture of Dark Matter hunters, says Reina Maruyama, a nuclear and particle physicist at Yale and co-leader of HAYSTAC. The field has long attracted people interested in developing new detectors and in quick, small-scale experiments, she says. “This kind of footloose approach has always been possible in the Dark Matter field.”

    For some novel searches, the simplest definition of a quantum sensor may do: It’s any device capable of detecting a single quantum particle, such as a photon or an energetic electron. “I call a quantum sensor something that can detect single quanta in whatever form that takes,” Zurek says. That’s what is needed for hunting particles slightly lighter than WIMPs and plumbing the dark sector, she says.

    Such runty particles wouldn’t produce detectable nuclear recoils. A wispy dark sector particle could interact with ordinary matter by emitting a dark photon that morphs into an ordinary photon. But that low-energy photon would barely nudge a nucleus.

    In the right semiconductor, however, the same photon could excite an electron and enable it to flow through the material. Kahn and Abbamonte are working on an extremely sensitive photodiode, a device that produces an electrical signal when it absorbs light. Were such a device shielded from light and other forms of radiation and cooled to near absolute zero to reduce noise, a Dark Matter signal would stand out as a steady pitter-pat of tiny electrical pulses.

    3
    A chip that could sense dark photons (first image) and an axion detector, HAYSTAC, could fit on a tabletop despite their high sensitivity. (First image) Roger Romani/University of California, Berkeley; (Second image) Karl Van Bibber.

    The trick is to find a semiconductor sensitive to very low-energy photons, Kahn says. The industrial standard, silicon, releases an electron when it absorbs a photon with an energy of at least 1.1 electron volts (eV). To detect dark sector particles with masses as low as 1/100,000th that of a proton, the material would need to unleash an electron when pinged by a photon of just 0.03 eV. So Kahn, Abbamonte, and colleagues at The DOE’s Los Alamos National Laboratory are exploring “narrow bandgap” semiconductors such as a compound of europium, indium, and antimony.

    Even lighter dark-sector particles would create photons with too little energy to liberate an electron in the most sensitive semiconductor. To hunt for them, Zurek and Matt Pyle, a detector physicist at the University of California, Berkeley, are developing a detector that would sense the infinitesimal quantized vibrations set off when a dark photon creates an ordinary photon that pings a nucleus. It would “only rattle that nucleus and produce a bunch of vibrations,” Pyle says. “So the detectors must be fundamentally different.”

    Their detector consists of a single crystal of material composed of two types of ions with opposite charges, such as gallium arsenide. The feeble photon spawned by a dark photon would nudge the different ions in opposite directions, setting off quantized vibrations called optical phonons. To detect these vibrations, Zurek and Pyle dot the crystal with small patches of tungsten and chill it to temperatures near absolute zero, where tungsten becomes a superconductor that carries electricity without resistance. Any phonons would slightly warm the tungsten, reducing its superconductivity and leading to a noticeable spike in its resistance.

    Within 5 years, the researchers hope to improve their detector’s sensitivity by a factor of 10 so that they can sense a single phonon and hunt dark-sector particles weighing one-millionth as much as a proton. To provide the Dark Matter, such particles would have to be so numerous that a detector weighing just a few kilograms should be able to spot them or rule them out. And because so few experiments have probed this mass range, even little prototype detectors unshielded from background radiation can yield interesting data, Pyle says. “We run just in our lab above ground, and we can get world-leading results.”

    Some physicists argue that true quantum sensors should do something more subtle. The Heisenberg uncertainty principle states that if you simultaneously measure the position and momentum of an electron, the product of the uncertainties in those measurements must exceed a “standard quantum limit.” That means no measurement can yield a perfectly precise result, no matter how it’s done. However, the principle also implies you can swap greater uncertainty in one measurement for greater precision in the other. To some physicists, a quantum sensor is one that exploits that trade-off.

    Physicists are using such schemes to enhance axion searches. To make up Dark Matter, those lightweight particles would be so numerous that en masse they’d act like a wave, just as sunlight acts more like a light wave than a hail of photons. So with their metal cavities, ADMX and HAYSTAC researchers are searching for the conversion of an invisible axion wave into a detectable radio wave.

    Like any wave, the radio wave will have an amplitude that reveals how strong it is and a phase that marks its exact synchronization relative to whatever ultraprecise clock you might choose. Conventional radio circuits measure both and run into a limit set by the uncertainty principle. But axion hunters care only about the signal’s amplitude—is a wave there or not?—and quantum mechanics lets them measure it with greater precision in exchange for more uncertainty in the phase.

    HAYSTAC experimenters exploit that trade-off to tamp down noise in their experiment. The vacuum—the backdrop for the measurement—can itself be considered a wave. Although that vacuum wave has on average zero amplitude, its amplitude is still uncertain and fluctuates to create noise. In HAYSTAC a special amplifier reduces the vacuum’s amplitude fluctuations while allowing those in the irrelevant phase to grow bigger, causing any axion signal to stand out more readily. Last year, HAYSTAC researchers reported in Nature that they had searched for and ruled out axions in a narrow range around 19-quadrillionths of a proton mass. By squeezing the noise, they increased the speed of the search by a factor of 2, Maruyama says, and validated the principle.

    Such “squeezing” has been demonstrated for decades in laboratory experiments with lasers and optics. Now, Irwin says, “These techniques for beating the standard quantum limit [have] been used to actually do something better, as opposed to do something in a demonstration.” In the DM Radio experiment, he hopes to use a related technique to probe for even lighter axions as well as dark photons.

    Instead of a resonating cavity, DM Radio consists of a radio circuit containing a charge-storing capacitor and a current-storing inductor—a carefully designed coil of wire—both placed in a magnetic field. Axions could convert to radio waves within the inductor coil to create a resonating signal in the circuit at a certain frequency. Researchers can also look for dark photons by reconfiguring the coil and turning off the magnetic field.

    To read out the signal, Irwin’s scheme plays on another implication of quantum mechanics, that by measuring a system’s state you may change it. The researchers couple their resonating circuit to a second, higher frequency circuit, so that, much as in AM radio, any Dark Matter signal would make the amplitude of the higher frequency carrier wave warble. The stronger the coupling, the bigger the warbling, and the more prominent the signal. But stronger coupling also injects noise that could stymie efforts to measure Dark Matter with greater precision.

    Again, a quantum trade-off comes to the rescue. The researchers modify their carrier wave by injecting a tiny warble at the frequency they hope to probe. Just by random chance, that input warble and any Dark Matter signal will likely be somewhat out of sync, or phase. But the Dark Matter wave can be thought of as the sum of two components: one that’s exactly in sync with the added signal and one that’s exactly out of sync with it—much as any direction on a map is a combination of north-south and east-west. The experiment is designed to measure the in-sync component with greater precision while injecting all the disturbance into the out-of-sync component, making the measurement more sensitive and accelerating the rate at which the experiment can scan different frequencies.

    Irwin and colleagues have already run a small prototype of the experiment. They are now building a larger version, and ultimately they plan one with a coil that has a volume of 1 cubic meter. Implementing the quantum sensing is essential, Irwin says, as without it, scanning the entire frequency range would take thousands of years.

    Some Dark Matter hunters are explicitly borrowing hardware from quantum computing. For example, Fermilab’s Chou and colleagues have used a superconducting qubit—the same kind Google and IBM use in their quantum computers—to perform a proof-of-principle search for dark photons in a very narrow energy range. Like a smaller version of ADMX or HAYSTAC, their experiment centers on a resonating cavity, this one drilled into the edge of an aluminum plate. There a dark photon could convert into radio waves, although at a higher frequency than in ADMX or HAYSTAC. Ordinarily, experimenters would bleed the radio waves out through a hole in the cavity and measure them with a low-noise amplifier. However, the tiny cavity would generate a signal so faint it would drown in noise from the amplifier itself.

    The qubit sidesteps that problem. Like any other qubit, the tiny superconducting circuit can act like a clock, cycling between different combinations of 0 and 1 at a rate that depends on the difference in energy between the circuit’s 0 and 1 states. That difference in turn depends on whether there are any radio photons in the cavity. Even one is enough to speed up the clock, Chou says. “We’re going to stick this artificial atomic clock in the cavity and see if it still keeps good time.”

    The measurement probes only the amplitude of the radio waves and not their phase, obtaining greater precision in the former in exchange for greater uncertainty in the latter, the team reported last year in Physical Review Letters. It might speed up dark photon searches by as much as a factor of 1300, Chou says, and it could be extended to search for axions, if researchers could apply a magnetic field to the cavity while shielding the sensitive qubit.

    One group has invented a scheme to search for WIMPs using another candidate qubit: a so-called nitrogen vacancy (NV) center within a diamond crystal. In an NV, a nitrogen atom replaces a carbon atom in the crystal lattice and creates an adjacent, empty site that collects a pair of electrons that can serve as qubit. A WIMP passing through a diamond can bump carbon atoms out of the way, leaving a trail of NVs roughly 100 nanometers long, says Ronald Walsworth, an experimental physicist at the University of Maryland, College Park. The NVs will absorb and emit light of specific wavelengths, so the track can be spotted clearly with fluorescence microscopy.

    That scheme has little to do with quantum computing, but it would address a looming problem for WIMP searches. If current liquid xenon detectors get much bigger, they should start to see well-known particles called neutrinos, which stream from the Sun. To tell a WIMP from a neutrino, physicists would need to know where a particle came from, as WIMPs should come from the plane of the Galaxy rather than the Sun. A liquid xenon detector can’t determine the direction of a particle that caused a signal. A detector made of diamonds could.

    Walsworth envisions a detector formed of millions of millimeter-size synthetic diamonds. A diamond would flash when pierced by a neutrino or WIMP, and an automated system would remove it and scan it for an NV track, using the time of the flash to determine the track’s orientation relative to the Sun and the Galaxy, the team explained last year in Quantum Science and Technology. Walsworth hopes to build a prototype detector in a few years. “I absolutely do not want to claim that our idea would work or that it’s better than other approaches,” he says. “But I think it’s promising enough to go forward.”

    Physicists have proposed many other ideas for using quantum sensors to search for Dark Matter, and the influx of money should help transform them into new technologies, Zurek says. “Things can move faster when you’re funded,” she says. As tool builders, Dark Matter hunters embrace that push. “They have a great hammer, so they started looking for nails,” Walsworth says. Perhaps they’ll bang out a discovery of cosmic proportions.

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

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

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

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

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

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

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

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

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

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

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

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

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

    See the full article here .


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  • richardmitnick 8:15 am on July 23, 2022 Permalink | Reply
    Tags: "Halos and dark matter:: A recipe for discovery", , Beryllium-10, Beta decay, Boron-11, Dark decay, Dark Matter, , Michigan State University NSCL [National Superconducting Cyclotron Laboratory], , , , Reaccelerator technology, The Michigan State University FRIB [Facility for Rare Isotope Beams], Time-reversed reaction, TRIUMF- Canada's particle accelerator centre [Centre canadien d'accélération des particules](CA)   

    From The Facility for Rare Isotope Beams [FRIB]: “Halos and dark matter:: A recipe for discovery” 

    From The Facility for Rare Isotope Beams [FRIB].

    At

    Michigan State Bloc

    Michigan State University

    July 22, 2022
    Matt Davenport

    1
    This Hubble Space Telescope image centers on what’s known as a low surface brightness, or LSB, galaxy (blue), surrounded by more familiar-looking galaxies (yellow). Astrophysics believe that more than 95% of the matter found in LSBs is dark matter. Credit: D. Calzetti/NASA/ESAHubble.

    Scientists still don’t know what Dark Matter is. But Michigan State University scientists helped uncover new physics while looking for it.

    About three years ago, Wolfgang “Wolfi” Mittig and Yassid Ayyad went looking for the universe’s missing mass, better known as Dark Matter, in the heart of an atom.

    Their expedition didn’t lead them to Dark Matter, but they still found something that had never been seen before, something that defied explanation. Well, at least an explanation that everyone could agree on.

    “We started out looking for Dark Matter and we didn’t find it,” he said. “Instead, we found other things that have been challenging for theory to explain.”

    So the team got back to work, doing more experiments, gathering more evidence to make their discovery make sense. Mittig, Ayyad and their colleagues bolstered their case at the National Superconducting Cyclotron Laboratory, or NSCL [below], at Michigan State University.

    Working at NSCL, the team found a new path to their unexpected destination, which they detailed June 28 in the journal Physical Review Letters [below]. In doing so, they also revealed interesting physics that’s afoot in the ultra-small quantum realm of subatomic particles.

    In particular, the team confirmed that when an atom’s core, or nucleus, is overstuffed with neutrons, it can still find a way to a more stable configuration by spitting out a proton instead.

    “It’s been something like a detective story,” said Mittig, a Hannah Distinguished Professor in Michigan State University’s Department of Physics and Astronomy and a faculty member at the Facility for Rare Isotope Beams [below].

    Shot in the dark

    Dark Matter is one of the most famous things in the universe that we know the least about. For decades, scientists have known that the cosmos contains more mass than we can see based on the trajectories of stars and galaxies.

    For gravity to keep the celestial objects tethered to their paths, there had to be unseen mass and a lot of it — six times the amount of regular matter that we can observe, measure and characterize. Although scientists are convinced Dark Matter is out there, they have yet to find where and devise how to detect it directly.

    “Finding Dark Matter is one of the major goals of physics,” said Ayyad, a nuclear physics researcher at the Galician Institute of High Energy Physics, or IGFAE, of the University of Santiago de Compostela in Spain.

    Speaking in round numbers, scientists have launched about 100 experiments to try to illuminate what exactly Dark Matter is, Mittig said.

    “None of them has succeeded after 20, 30, 40 years of research,” he said.

    “But there was a theory, a very hypothetical idea, that you could observe Dark Matter with a very particular type of nucleus,” said Ayyad, who was previously a detector systems physicist at NSCL.

    This theory centered on what it calls a dark decay. It posited that certain unstable nuclei, nuclei that naturally fall apart, could jettison Dark Matter as they crumbled.
    __________________________________
    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

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

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

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

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

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

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

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

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

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

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

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

    So Ayyad, Mittig and their team designed an experiment that could look for a dark decay, knowing the odds were against them. But the gamble wasn’t as big as it sounds because probing exotic decays also lets researchers better understand the rules and structures of the nuclear and quantum worlds.

    The researchers had a good chance of discovering something new. The question was what that would be.

    Help from a halo

    When people imagine a nucleus, many may think of a lumpy ball made up of protons and neutrons, Ayyad said. But nuclei can take on strange shapes, including what are known as halo nuclei.

    Beryllium-11 is an example of a halo nucleus. It’s a form, or isotope, of the element beryllium that has four protons and seven neutrons in its nucleus. It keeps 10 of those 11 nuclear particles in a tight central cluster. But one neutron floats far away from that core, loosely bound to the rest of the nucleus, kind of like the moon ringing around the Earth, Ayyad said.

    Beryllium-11 is also unstable. After a lifetime of about 13.8 seconds, it falls apart by what’s known as beta decay. One of its neutrons ejects an electron and becomes a proton. This transforms the nucleus into a stable form of the element boron with five protons and six neutrons, boron-11.

    2
    In the team’s experiment published in 2019, beryllium-11 decays through beta decay to an excited state of boron-11, which decays to beryllium-10 and a proton. In the new experiment, the team accesses the boron-11 state by adding a proton to beryllium-10, that is, by running the time-reversed reaction.

    But according to that very hypothetical theory, if the neutron that decays is the one in the halo, beryllium-11 could go an entirely different route: It could undergo a dark decay.

    In 2019, the researchers launched an experiment at Canada’s national particle accelerator facility, TRIUMF- Canada’s particle accelerator centre [Centre canadien d’accélération des particules](CA), looking for that very hypothetical decay.

    And they did find a decay with unexpectedly high probability, but it wasn’t a dark decay.

    It looked like the beryllium-11’s loosely bound neutron was ejecting an electron like normal beta decay, yet the beryllium wasn’t following the known decay path to boron.

    The team hypothesized that the high probability of the decay could be explained if a state in boron-11 existed as a doorway to another decay, to beryllium-10 and a proton. For anyone keeping score, that meant the nucleus had once again become beryllium. Only now it had six neutrons instead of seven.

    “This happens just because of the halo nucleus,” Ayyad said. “It’s a very exotic type of radioactivity. It was actually the first direct evidence of proton radioactivity from a neutron-rich nucleus.”

    But science welcomes scrutiny and skepticism, and the team’s 2019 report was met with a healthy dose of both. That “doorway” state in boron-11 did not seem compatible with most theoretical models. Without a solid theory that made sense of what the team saw, different experts interpreted the team’s data differently and offered up other potential conclusions.

    “We had a lot of long discussions,” Mittig said. “It was a good thing.”

    As beneficial as the discussions were — and continue to be — Mittig and Ayyad knew they’d have to generate more evidence to support their results and hypothesis. They’d have to design new experiments.

    The NSCL experiments

    In the team’s 2019 experiment, TRIUMF generated a beam of beryllium-11 nuclei that the team directed into a detection chamber where researchers observed different possible decay routes. That included the beta decay to proton emission process that created beryllium-10.

    For the new experiments, which took place in August 2021, the team’s idea was to essentially run the time-reversed reaction. That is, the researchers would start with beryllium-10 nuclei and add a proton.

    Collaborators in Switzerland created a source of beryllium-10, which has a half-life of 1.4 million years, that NSCL could then use to produce radioactive beams with new reaccelerator technology. The technology evaporated and injected the beryllium into an accelerator and made it possible for researchers to make a highly sensitive measurement.

    When beryllium-10 absorbed a proton of the right energy, the nucleus entered the same excited state the researchers believed they discovered three years earlier. It would even spit the proton back out, which can be detected as signature of the process.

    “The results of the two experiments are very compatible,” Ayyad said.

    That wasn’t the only good news. Unbeknownst to the team, an independent group of scientists at Florida State University had devised another way to probe the 2019 result. Ayyad happened to attend a virtual conference where the Florida State team presented its preliminary results, and he was encouraged by what he saw.

    “I took a screenshot of the Zoom meeting and immediately sent it to Wolfi,” he said. “Then we reached out to the Florida State team and worked out a way to support each other.”

    The two teams were in touch as they developed their reports, and both scientific publications now appear in the same issue of Physical Review Letters [below]. And the new results are already generating a buzz in the community.

    “The work is getting a lot of attention. Wolfi will visit Spain in a few weeks to talk about this,” Ayyad said.

    An open case on open quantum systems

    Part of the excitement is because the team’s work could provide a new case study for what are known as open quantum systems. It’s an intimidating name, but the concept can be thought of like the old adage, “nothing exists in a vacuum.”

    3
    In an open quantum system, a discrete, or isolated, state, analogous to boron-11 (left), mixes with an adjacent continuum of states, related to beryllium-10 (middle), which results in a new “resonant” state (right). Credit: Facility for Rare Isotope Beams.

    Quantum physics has provided a framework to understand the incredibly tiny components of nature: atoms, molecules and much, much more. This understanding has advanced virtually every realm of physical science, including energy, chemistry and materials science.

    Much of that framework, however, was developed considering simplified scenarios. The super small system of interest would be isolated in some way from the ocean of input provided by the world around it. In studying open quantum systems, physicists are venturing away from idealized scenarios and into the complexity of reality.

    Open quantum systems are literally everywhere, but finding one that’s tractable enough to learn something from is challenging, especially in matters of the nucleus. Mittig and Ayyad saw potential in their loosely bound nuclei and they knew that NSCL, and now FRIB could help develop it.

    NSCL, a National Science Foundation user facility that served the scientific community for decades, hosted the work of Mittig and Ayyad, which is the first published demonstration of the stand-alone reaccelerator technology. FRIB, a U.S. Department of Energy Office of Science user facility that officially launched on May 2, 2022 is where the work can continue in the future.

    “Open quantum systems are a general phenomenon, but they’re a new idea in nuclear physics,” Ayyad said. “And most of the theorists who are doing the work are at FRIB.”

    But this detective story is still in its early chapters. To complete the case, researchers still need more data, more evidence to make full sense of what they’re seeing. That means Ayyad and Mittig are still doing what they do best and investigating.

    “We’re going ahead and making new experiments,” said Mittig. “The theme through all of this is that it’s important to have good experiments with strong analysis.”

    NSCL was a national user facility funded by the National Science Foundation, supporting the mission of the Nuclear Physics program in the NSF Physics Division.

    Michigan State University (MSU) operates the Facility for Rare Isotope Beams (FRIB) as a user facility for the U.S. Department of Energy Office of Science (DOE-SC), supporting the mission of the DOE-SC Office of Nuclear Physics. Hosting what is designed to be the most powerful heavy-ion accelerator, FRIB enables scientists to make discoveries about the properties of rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions and applications for society, including in medicine, homeland security and industry.

    The U.S. Department of Energy Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of today’s most pressing challenges. For more information, visit energy.gov/science.

    Science paper:
    Physical Review Letters

    Physical Review Letters

    See the full article here .


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    Michigan State Campus

    Michigan State University is a public research university located in East Lansing, Michigan, United States. Michigan State University was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

    U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the Facility for Rare Isotope Beams, and the country’s largest residence hall system.

    Research

    The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at Michigan State University, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

    Today Michigan State University continues its research with facilities such as the Department of Energy -sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

    Michigan State University FRIB [Facility for Rare Isotope Beams] .

    In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University, in consortium with the University of North Carolina at Chapel Hill and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.

    The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, MSU has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.


    The Michigan State University Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019. In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.

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

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

    Symmetry Mag

    From “Symmetry”

    07/19/22
    Katrina Miller

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

    1
    Illustration by Sandbox Studio, Chicago with Olena Shmahalo.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    Fritz Zwicky.
    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

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

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

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

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

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

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

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

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

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

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

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

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

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

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

    See the full article here .


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

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:35 am on July 11, 2022 Permalink | Reply
    Tags: "Dark matter:: our review suggests it’s time to ditch it in favor of a new theory of gravity", , But Mond doesn’t merely explain such rotation curves. In many cases it predicts them., Dark Matter, , Mond’s main postulate is that when gravity becomes very weak-as occurs at the edge of galaxies-it starts behaving differently from Newtonian physics., , , , The problems with dark matter   

    From “The Conversation (AU)” : “Dark matter:: our review suggests it’s time to ditch it in favor of a new theory of gravity” 

    From “The Conversation (AU)”

    July 7, 2022
    Indranil Banik
    Postdoctoral Research Fellow of Astrophysics,
    University of St Andrews (SCT)

    1
    The barred spiral galaxy UGC 12158. Wikimedia , CC BY-SA.

    “We can model the motions of planets in the Solar System quite accurately using Newton’s laws of physics. But in the early 1970s, scientists noticed that this didn’t work for disc galaxies – stars at their outer edges, far from the gravitational force of all the matter at their centre – were moving much faster than Newton’s theory predicted.

    This made physicists propose that an invisible substance called “dark matter” was providing extra gravitational pull, causing the stars to speed up – a theory that’s become hugely popular. However, in a recent review [MDPI] my colleagues and I suggest that observations across a vast range of scales are much better explained in an alternative theory of gravity proposed by Israeli physicist Mordehai Milgrom in 1982 called Milgromian dynamics or Mond – requiring no invisible matter.

    ___________________________________________
    MOND [Modified Newtonian dynamics]

    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’s main postulate is that when gravity becomes very weak-as occurs at the edge of galaxies-it starts behaving differently from Newtonian physics. In this way, it is possible to explain [Astronomy & Astrophysics] why stars, planets and gas in the outskirts of over 150 galaxies rotate faster than expected based on just their visible mass. But Mond doesn’t merely explain such rotation curves. In many cases it predicts them.

    Philosophers of science have argued [Cambridge Core] that this power of prediction makes Mond superior to the standard cosmological model, which proposes there is more dark matter in the universe than visible matter. This is because, according to this model, galaxies have a highly uncertain amount of dark matter that depends on details of how the galaxy formed – which we don’t always know. This makes it impossible to predict how quickly galaxies should rotate. But such predictions are routinely made with Mond, and so far these have been confirmed.

    Imagine that we know the distribution of visible mass in a galaxy but do not yet know its rotation speed. In the standard cosmological model, it would only be possible to say with some confidence that the rotation speed will come out between 100km/s and 300km/s on the outskirts. Mond makes a more definite prediction that the rotation speed must be in the range 180-190km/s.

    If observations later reveal a rotation speed of 188km/s, then this is consistent with both theories – but clearly, Mond is preferred. This is a modern version of “Occam’s razor” – that the simplest solution is preferable to more complex ones, in this case that we should explain observations with as few “free parameters” as possible. Free parameters are constants – certain numbers that we must plug into equations to make them work. But they are not given by the theory itself – there’s no reason they should have any particular value – so we have to measure them observationally. An example is the gravitation constant, G, in Newton’s gravity theory or the amount of dark matter in galaxies within the standard cosmological model.

    We introduced a concept known as “theoretical flexibility” to capture the underlying idea of Occam’s razor that a theory with more free parameters is consistent with a wider range of data – making it more complex. In our review, we used this concept when testing the standard cosmological model and Mond against various astronomical observations, such as the rotation of galaxies and the motions within galaxy clusters.

    Each time, we gave a theoretical flexibility score between –2 and +2. A score of –2 indicates that a model makes a clear, precise prediction without peeking at the data. Conversely, +2 implies “anything goes” – theorists would have been able to fit almost any plausible observational result (because there are so many free parameters). We also rated how well each model matches the observations, with +2 indicating excellent agreement and –2 reserved for observations that clearly show the theory is wrong. We then subtract the theoretical flexibility score from that for the agreement with observations, since matching the data well is good – but being able to fit anything is bad.

    A good theory would make clear predictions which are later confirmed, ideally getting a combined score of +4 in many different tests (+2 -(-2) = +4). A bad theory would get a score between 0 and -4 (-2 -(+2)= -4). Precise predictions would fail in this case – these are unlikely to work with the wrong physics.

    We found an average score for the standard cosmological model of –0.25 across 32 tests, while Mond achieved an average of +1.69 across 29 tests. The scores for each theory in many different tests are shown in figures 1 and 2 below for the standard cosmological model and Mond, respectively.

    1
    Comparison of the standard cosmological model with observations based on how well the data matches the theory (improving bottom to top) and how much flexibility it had in the fit (rising left to right). The hollow circle is not counted in our assessment, as that data was used to set free parameters. Reproduced from table 3 of our review. Arxiv.

    2
    Similar to Figure 1, but for Mond with hypothetical particles that only interact via gravity called sterile neutrinos. Notice the lack of clear falsifications. Reproduced from Table 4 of our review. Arxiv.

    It is immediately apparent that no major problems were identified for Mond, which at least plausibly agrees with all the data (notice that the bottom two rows denoting falsifications are blank in figure 2).

    The problems with dark matter

    One of the most striking failures of the standard cosmological model relates to “galaxy bars” – rod-shaped bright regions made of stars – that spiral galaxies often have in their central regions (see lead image). The bars rotate over time. If galaxies were embedded in massive halos of dark matter, their bars would slow down. However, most, if not all, observed galaxy bars are fast. This falsifies the standard cosmological model with very high confidence.

    Another problem is that the original models that suggested galaxies have dark matter halos made a big mistake – they assumed that the dark matter particles provided gravity to the matter around it, but were not affected by the gravitational pull of the normal matter. This simplified the calculations, but it doesn’t reflect reality. When this was taken into account in subsequent simulations it was clear that dark matter halos around galaxies do not reliably explain their properties.

    There are many other failures of the standard cosmological model that we investigated in our review, with Mond often able to naturally explain the observations. The reason the standard cosmological model is nevertheless so popular could be down to computational mistakes or limited knowledge about its failures, some of which were discovered quite recently. It could also be due to people’s reluctance to tweak a gravity theory that has been so successful in many other areas of physics.

    The huge lead of Mond over the standard cosmological model in our study led us to conclude that Mond is strongly favored by the available observations. While we do not claim that Mond is perfect, we still think it gets the big picture correct – galaxies really do lack dark matter.

    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 Conversation (AU) launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.

    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
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