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  • richardmitnick 4:37 pm on February 19, 2019 Permalink | Reply
    Tags: Accelerator Science, , , Looking for Dak Energy at CERN,   

    From Symmetry: “Taking a collider to the dark energy problem” 

    Symmetry Mag
    From Symmetry

    02/14/19
    Sarah Charley

    1
    Ralf Kaehler, based on a simulation by John Wise and Tom Abel

    Every second, the universe grows a little bigger. Scientists are using the LHC to try to find out why.

    With the warmth of holiday cheer in the air, Nottingham University theoretical physicist Clare Burrage and her colleagues decided to hit the pub after a conference in December 2014 and do what many physicists tend to do after work: keep talking about physics.

    That evening’s topic of conversation: dark energy particles. The chat would lead to a new line of investigation at the Large Hadron Collider at CERN.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    Dark energy is a catch-all term that scientists coined to describe whatever seems to be pushing the bounds of the universe farther and farther apart. If gravity were the only force choreographing the interstellar ballet of stars and galaxies, then—after the initial grand jeté of all of the matter and energy in the universe during the big bang—every celestial body would slowly chassé back to a central point. But that’s not what’s happening. Instead, the universe continues to drift apart—and it’s happening at an accelerating rate.

    “We really don’t know what’s going on,” says Burrage. “At the moment, there are problems with all of our possible solutions to this problem.”

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


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

    Most experiments studying this mysterious cosmic expansion look at intergalactic movements and precision measurements of the effects of gravity. Dark energy could be a property of spacetime itself, or just a huge misunderstanding of how gravity works on a cosmic scale.

    But many theorists suspect that dark energy is a new type of force or field—something that changes how gravity works. And if this is true, then scientists might be able to put just the right amount of energy into that field to pop out a particle, a particle that could potentially show up in a detector at the LHC. This is the way scientists discovered the Higgs field, by interacting with it in just the right way for it to produce a Higgs boson.

    CERN CMS Higgs Event


    CERN ATLAS Higgs Event

    “Cosmologists know that there is new physics we don’t understand, and all the evidence is pointing towards something very fundamental about our universe,” Burrage says. “The experiments on the LHC are also very interested in the fundamentals.”

    The ATLAS and CMS experiments, the big general-purpose experiments at the LHC, search for new fundamental forces and properties of nature by recording what happens when the LHC smashes together protons at just under the speed of light.

    CERN/ATLAS detector


    The giant detectors surround the collision points and map the energy and matter released from the collisions, giving scientists a unique view of the clandestine threads that weave together to build everything in the universe.

    The theory Burrage and her colleagues were poring over at the pub predicted that if dark energy is a new type of field, it might produce light particles with strong and specific interactions with matter. “The main focus of LHC has been heavy particles, so we had to go back and re-interpret the data to look for something light,” she says.

    Burrage worked with Philippe Brax of Université Paris-Saclay and Christophe Englert of the University of Glasgow to check publicly available data from the first run of the world’s most powerful collider for signs of a lightweight dark energy particles. They quickly determined that the signs they were looking for had not appeared.

    With this simple model easily eliminated, they decided to take on another idea with a more cryptic signature. They knew that more complex analyses would require the expertise of an experimentalist. So in April 2016, along with Michael Spannowsky of Durham University in the UK, they published a new hypothesis in the scientific journal Physical Review Letters—and waited.

    They found their experimentalist in Spyros Argyropoulos, a postdoc at the University of Iowa working on the ATLAS experiment, who read their article.

    “The idea of testing dark energy was intriguing,” Argyropoulos says. “It’s not something we typically look for at the LHC, and making progress on this problem is a win-win for both cosmologist and particle physicist.”

    Argyropoulos reached out to Burrage and her colleagues to define the parameters, and then he and a group of ATLAS scientists went to the data.

    According to this new theory, dark energy particles should radiate off of energetic top quarks and show up in the detector as missing energy. Argyropoulos and his colleagues went through ATLAS analyses of top quarks and, in a separate search, looked at certain other collisions to see if any of them showed the signatures they were looking for. They did not.

    While this might seem like a disappointing result, Argyropoulos assures that it’s anything but. “Physics isn’t just about finding the right answer,” he says. “It’s also about narrowing down all the possibilities.”

    Burrage agrees: “Eliminating an idea with experimental data is a positive thing, even if it means our pet theory gets killed in the process. Theorists can always come up with more ideas, and it’s good for the field to have the spectrum of possibilities narrowed down.”

    The landscape of dark energy theories is enormous. Burrage’s specialty is scouring that landscape, searching for theories that can be tested, and then proposing ways to test them.

    “Ten years ago, nobody was thinking that collider physics could put constraints on dark energy searches,” she says. “Theories have to pass all relevant experimental tests, and it’s looking like surviving the Large Hadron Collider is going to be an important one to our field.”

    See the full article here .


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    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 8:42 pm on February 15, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , , ,   

    From CERN CMS: “CMS gets first result using largest ever LHC data sample” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN CMS

    15 February, 2019

    The CMS collaboration at CERN has submitted its first paper based on the full LHC dataset collected in 2018 and data collected in 2016 and 2017.

    Just under three months after the final proton–proton collisions from the Large Hadron Collider (LHC)’s second run (Run 2), the CMS collaboration has submitted its first paper [Physical Review Letters] based on the full LHC dataset collected in 2018 – the largest sample ever collected at the LHC – and data collected in 2016 and 2017. The findings reflect an immense achievement, as a complex chain of data reconstruction and calibration was necessary to be able to use the data for analysis suitable for a scientific result.

    “It is truly a sign of effective scientific collaboration and the high quality of the detector, software and the CMS collaboration as a whole. I am proud and extremely impressed that the understanding of the so recently collected data is sufficiently advanced to produce this very competitive and exciting result,” said CMS spokesperson Roberto Carlin.

    Quantum chromodynamics (QCD) is one of the pillars of the Standard Model of elementary particles and describes how quarks and gluons are confined within composite particles called hadrons, of which protons and neutrons are examples.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    However, the QCD processes behind this confinement are not yet well understood, despite much progress in the last two decades. One way to understand these processes is to study the little known Bc particle family, which consists of hadrons composed of a beauty quark and a charm antiquark (or vice-versa).

    The high collision energies and rates provided by the Large Hadron Collider opened the path for the exploration of the Bc family. The first studies were published in 2014 [Physical Review Letters] by the ATLAS collaboration, using data collected during LHC’s first run. At the time, ATLAS reported the observation of a Bc particle called Bc(2S). On the other hand, the LHCb collaboration reported in 2017 that their data showed no evidence of Bc(2S) at all. Analysing the large LHC Run 2 data sample, collected in 2016, 2017 and 2018, CMS has now observed Bc(2S) as well as another Bc particle known as Bc*(2S). The collaboration has also been able to measure the mass of Bc(2S) with a good precision. These measurements provide a rich source of information on the QCD processes that bind heavy quarks into hadrons. For more information about the results visit the CMS webpage.

    The results presented at CERN this week.

    See the full article here.


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

    Stem Education Coalition

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN map

    CERN LHC Grand Tunnel

    CERN LHC particles

     
  • richardmitnick 7:09 pm on February 13, 2019 Permalink | Reply
    Tags: A key link in CERN’s accelerator complex, A new set of quadrupole magnets will be installed along the Booster-to-PS injection line, Accelerator Science, Also delivering particles to several experimental areas such as the Antiproton Decelerator (AD), , , CERN Proton Synchrotron, , It takes ten hours to extract one magnet, , Mainly accelerating protons to 26 GeV before sending them to the Super Proton Synchrotron (SPS), New cooling systems are being installed to increase the cooling capacity of the PS, One major component of the PS that will be consolidated is the magnet system, One of the elements known as the pole-face windings which is located between the beam pipe and the magnet yoke needs replacing, , PS will undergo a major overhaul to prepare it for the higher injection and beam intensities of the LHC’s Run 3 as well as for the High-Luminosity LHC   

    From CERN- “LS2 report: The Proton Synchrotron’s magnets prepare for higher energies” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    13 February, 2019
    Achintya Rao

    CERN Proton Synchrotron

    1
    One of the magnets being driven on a locomotive to the workshop (right) after being extracted from the PS itself (left) (Image: Julien Marius Ordan/Maximilien Brice/CERN)

    The Proton Synchrotron (PS), which was CERN’s first synchrotron and which turns 60 this year, once held the record for the particle accelerator with the highest energy. Today, it forms a key link in CERN’s accelerator complex, mainly accelerating protons to 26 GeV before sending them to the Super Proton Synchrotron (SPS), but also delivering particles to several experimental areas such as the Antiproton Decelerator (AD). Over the course of Long Shutdown 2 (LS2), the PS will undergo a major overhaul to prepare it for the higher injection and beam intensities of the LHC’s Run 3 as well as for the High-Luminosity LHC.

    One major component of the PS that will be consolidated is the magnet system [Many magnets will come from Fermilab and Brookhaven Lab, two US D.O.E. labs]. The synchrotron has a total of 100 main magnets within it (plus one reference magnet unit outside the ring), which bend and focus the particle beams as they whizz around it gaining energy. “During the last long shutdown (LS1) and at the beginning of LS2, the TE-MSC team performed various tests to identify weak points in the magnets,” explains Fernando Pedrosa, who is coordinating the LS2 work on the PS. The team identified 50 magnets needing refurbishment, of which seven were repaired during LS1 itself. “The remaining 43 magnets that need attention will be refurbished this year.”

    Specifically, one of the elements, known as the pole-face windings, which is located between the beam pipe and the magnet yoke, needs replacing. In order to reach into the magnet innards to replace these elements, the magnet units have to be transferred to a workshop in building 151. Once disconnected, each magnet is placed onto a small locomotive system that drives them to the workshops. The locomotives themselves are over 50 years old, and their movement must be delicately managed. It takes ten hours to extract one magnet. So far, six magnets have been taken to the workshop and this work will last until 18 October 2019.

    The workshop where the magnets are being treated is divided into two sections. In the first room, the vacuum chamber of the magnets is cut so as to access the pole-face windings. The magnet units are then taken to the second room, where prefabricated replacements are installed.

    As mentioned in the previous LS2 Report, the PS Booster will see an increase in the energy it imparts to accelerating protons, from 1.4 GeV to 2 GeV. A new set of quadrupole magnets will be installed along the Booster-to-PS injection line, to increase the focusing strength required for the higher-energy beams. Higher-energy beams require higher-energy injection elements; therefore some elements will be replaced in the PS injection region as part of the LHC Injectors Upgrade (LIU) project, namely septum 42, kicker 45 and five bumper magnets.

    Other improvements as part of the LIU project include the new cooling systems being installed to increase the cooling capacity of the PS. A new cooling station is being built at building 355, while one cooling tower in building 255 is being upgraded. The TT2 line, which is involved in the transfer from the PS to the SPS, will have its cooling system decoupled from the Booster’s, to allow the PS to operate independent of the Booster schedule. “The internal dumps of the PS, which are used in case the beam needs to be stopped, are also being changed, as are some other intercepting devices,” explains Pedrosa.

    The LS2 operations are on a tight schedule,” notes Pedrosa, pointing out that works being performed on several interconnected systems create constraints for what can be done concurrently. As LS2 proceeds, we will bring you more news about the PS, including the installation of new instrumentation in wire scanners that help with beam-size measurement, an upgraded transverse-feedback system to stabilise the beam and more.

    See the full article here.


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

    Stem Education Coalition

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN map

    CERN LHC Grand Tunnel

    CERN LHC particles

     
  • richardmitnick 3:42 pm on February 13, 2019 Permalink | Reply
    Tags: "Building a billion pixel detector for the Large Hadron Collider, Accelerator Science, , , , , , , STFC’s Daresbury Laboratory   

    From Science and Technology Facilities Council: “Building a billion pixel detector for the Large Hadron Collider” 


    From Science and Technology Facilities Council

    13 February 2019

    Wendy Ellison
    STFC Communications
    Daresbury Laboratory
    Sci-Tech Daresbury
    WA4 4AD
    Tel: 01925 603232

    Scientists, engineers and technicians at Daresbury Laboratory are playing a key role in building ground-breaking new technologies that will enable a major upgrade of the ALICE experiment, one of the four main detectors at the Large Hadron Collider at CERN.

    STFC Daresbury Laboratory-Hub for Pioneering Research


    CERN/ALICE Detector

    1
    Gary Markey and Terry Lee, mechanical technicians at Daresbury Laboratory, building the staves that are now on their way to ALICE at CERN.
    (Credit: STFC)

    3
    University of Liverpool Physicist, Dr Giacomo Contin, prepares the staves for shipment from Daresbury to CERN.
    (Credit: STFC)

    Weighing more than the Eiffel Tower and sitting in a vast cavern 56m below the ground, ALICE acts like a giant microscope that is used to observe and study a state of matter that was last present in the universe just billionths of a second after the Big Bang. The LHC is used to create this matter, which has a temperature around 400,000 times that of the sun, by accelerating and then colliding heavy nuclei of lead. Research at ALICE allows us to reconstruct and provide new insights into the physics of the early universe when, 13.8 billion years ago, in the moments after the Big Bang, the Universe consisted of a primordial soup of particles called Quark-Gluon Plasma.

    Quark-Gluon Plasma from BNL RHIC

    ‘Perfect liquid’ quark-gluon plasma is the most vortical fluid from phys.org

    The ALICE upgrade is a significant international project, and the team at STFC’s Daresbury Laboratory, in collaboration with the University of Liverpool, has been developing and building ground-breaking new technologies as part of a new Inner Tracking System. Extremely thin and highly-pixelated sensors, together with ultra-light support structures will boost the tracking performance of ALICE by a factor of a hundred. It will be the thinnest, most pixelated tracker at the LHC, capable of identifying and measuring the energy of particles created by the LHC’s collisions at lower energies than any of the other LHC experiments.

    The Daresbury-Liverpool team is building 30 staves of this new generation of sensor, each containing millions of pixels. The staves, which frame and support the sensors, are now being carefully transported to CERN in batches every six weeks until the end of September, where they will be tested before being installed, officially making ALICE a billion pixel detector.

    Dr Roy Lemmon, physicist and lead for the ALICE upgrade project at STFC’s Daresbury Laboratory, which is located at Sci-Tech Daresbury, said: “This project highlights the skills and significant role of the UK’s researchers in the development of new generations of technology for, in this case, ALICE, part of the world’s largest science experiment. It’s very exciting to be part of something that will not only help solve our science challenges, but which could also impact our lives in a really positive way, such as through improvements in medical imaging, through the development of new technologies.”

    “The ALICE upgrade is taking place during the scheduled two-year shutdown for the LHC. The newly-upgraded experiment will start taking data in 2021.

    Further information about ALICE at the CERN website.

    Further information about Daresbury Laboratory at the STFC website.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    STFC Hartree Centre

    Helping build a globally competitive, knowledge-based UK economy

    We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

    Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
    Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
    National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
    Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

    We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

    STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

    Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

    They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

    Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

    The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

    We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

    Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

     
  • richardmitnick 11:24 am on February 13, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , , , ,   

    From Ethan Siegel: “We Must Not Give Up On Answering The Biggest Scientific Questions Of All” 

    From Ethan Siegel
    Feb 12, 2019

    1
    The doubly charmed baryon, Ξcc++, contains two charm quarks and one up quark, and was first experimentally discovered at CERN. Now, researchers have simulated how to synthesize it from other charmed baryons that ‘melt’ together, and the energy yields are tremendous. To uncover yet-unrevealed truths about the Universe requires investing in experiments that have never yet been performed. (DANIEL DOMINGUEZ, CERN)

    Theoretical work tells you where to look, but only experiments can reveal what you’ll find.

    There are fundamental mysteries out there about the nature of the Universe itself, and it’s our inherent curiosity about those unanswered questions that drives science forward. There’s an incredible amount we’ve learned already, and the successes of our two leading theories — the quantum field theory describing the Standard Model and General Relativity for gravity — is a testament to how far we’ve come in understanding reality itself.

    Many people are pessimistic about our current attempts and future plans to try and solve the great cosmic mysteries that stymie us today. Our best hypotheses for new physics, including supersymmetry, extra dimensions, technicolor, string theory and more, have all failed to yield any experimental confirmation at all. But that doesn’t mean physics is in crisis. It means it’s working exactly as we’d expect: by telling the truth about the Universe. Our next steps will show us how well we’ve been listening.

    2
    From macroscopic scales down to subatomic ones, the sizes of the fundamental particles play only a small role in determining the sizes of composite structures. Whether the building blocks are truly fundamental and/or point-like particles is still not known.(MAGDALENA KOWALSKA / CERN / ISOLDE TEAM)

    CERN ISOLDE

    3
    The ALPHA-g detector, built at Canada’s particle accelerator facility, TRIUMF, is the first of its kind designed to measure the effect of gravity on antimatter. When oriented vertically, it should be able to measure in which direction antimatter falls, and at what magnitude. Experiments such as this were unfathomable a century ago, as antimatter’s existence was not even known. (STU SHEPHERD/TRIUMF)

    4
    In nuclear fusion, two lighter nuclei fuse together to create a heavier one, but where the final products have less mass than the initial reactants, and where energy is therefore released via E = mc². In the ‘melting quark’ scenario, two baryons with heavy quarks produce a doubly-heavy baryon, releasing energy via the same mechanism.(GERALD A. MILLER / NATURE)

    With everything we know about the fundamental particles, we know there should be more to the Universe than just the ones we know of. We cannot explain dark matter’s apparent existence, nor do we understand dark energy or why the Universe expands with the properties it does.

    We do not know why the particles have the masses that they do, why matter dominates the Universe and not antimatter, or why neutrinos have mass at all. We do not know if the proton is stable or will someday decay, or whether gravity is an inherently quantum force in nature. And even though we know the Big Bang was preceded by inflation, we do not know whether inflation itself had a beginning, or was eternal to the past.

    5
    There is certainly new physics beyond the Standard Model, but it might not show up until energies far, far greater than what a terrestrial collider could ever reach. Still, whether this scenario is true or not, the only way we’ll know is to look. In the meantime, properties of the known particles can be better explored with a future collider than any other tool. (UNIVERSE-REVIEW.CA)

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Most of the ideas one can concoct in physics have already been either ruled out or highly constrained by the data we already have in our coffers. If you want to discover a new particle, field, interaction, or phenomenon, it doesn’t do you any good to postulate something that’s inconsistent with what we already know to be true today. Sure, there might be assumptions we’ve made that later turn out to be incorrect, but the data itself must be in agreement with any new theory.

    6
    The vertices shown in the above Feynman diagrams all contain three Higgs bosons meeting at a single point, which would enable us to measure the Higgs self-coupling, a key parameter in understanding fundamental physics. (ALAIN BLONDEL AND PATRICK JANOT / ARXIV:1809.10041)

    That’s why the greatest amount of effort in physics goes not into new theories or new ideas, but into experiments that push past the regimes we’ve already explored. Sure, finding the Higgs boson may make tremendous headlines, but how strongly does the Higgs couple to the Z-boson? What are all the couplings between those two particles and the others in the Standard Model? How easy are they to create? And once you create them, are there any mutual decays that are different from a standard Higgs decay plus a standard Z-boson decay?

    There’s a technique you can use to probe this: create an electron-positron collision at exactly the mass of the Higgs plus the Z-boson. Instead of a few dozen to perhaps 100 events that create both a Higgs and a Z-boson, which is what the LHC has yielded, you can create thousands, hundreds of thousands, or even millions.

    7
    When you collide electrons at high energies with hadrons (such as protons) moving in the opposite direction at high energies, you can gain the ability to probe the internal structure of the hadrons as never before. This was a trememdous advance of the DESY (German Electron Synchrotron) experiment. (JOACHIM MEYER; DESY / HERA)

    H1 detector at DESY HERA ring

    Not every experiment is designed to make new particles, nor should they be. Some are designed to probe matter that we already know exists, and to study its properties in detail as never before. LEP, the Large Electron-Positron collider and the predecessor to the LHC, never found a single new fundamental particle. Neither did the DESY experiment, which collided electrons with protons. Neither did RHIC, the Relativistic Heavy Ion Collider.

    CERN LEP Collider

    BNL/RHIC


    And that’s to be expected; that wasn’t the point of those colliders. Their purpose was to study the matter that we know exists to never-before-studied precisions.

    6
    With six quarks and six antiquarks to choose from, where their spins can sum to 1/2, 3/2 or 5/2, there are expected to be more pentaquark possibilities than all baryon and meson possibilities combined.(CERN / LHC / LHCB COLLABORATION)

    CERN/LHCb detector

    The purpose of the next great science experiment isn’t to simply look for one new thing or test one new theory. It’s to gather a huge suite of otherwise unattainable data, and to let that data guide the development of the field.

    8
    A hypothetical new accelerator, either a long linear one or one inhabiting a large tunnel beneath the Earth, could dwarf the LHC’s energies. Even at that, there’s no guarantee we’ll find anything new, but we’re certain to find nothing new if we fail to try. (ILC COLLABORATION)

    Linear Collider Collaboration

    CERN FCC Future Circular Collider details of proposed 100km-diameter successor to LHC

    Proposed Future Colliders

    Sure, we can design and build experiments or observatories with an eye towards what we anticipate might be there. But the best bet for the future of science is a multi-purpose machine that can gather large and varied amounts of data that could never be collected without such a tremendous investment. It’s why Hubble was so successful, why Fermilab and the LHC have pushed boundaries as never before, and why future missions such as the James Webb Space Telescope, future 30-meter class observatories like the GMT or the ELT, or future colliders beyond the LHC such as the FCC, CLIC, or the ILC are required if we ever hope to answer the most fundamental questions of all.

    NASA/ESA Hubble Telescope


    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    NASA/ESA/CSA Webb Telescope annotated

    Giant Magellan Telescope, to be at the Carnegie Institution for Science’s Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).

    CLIC collider

    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan

    There’s an old saying in business that applies to science just as well: “Faster. Better. Cheaper. Pick two.” The world is moving faster than ever before. If we start pinching pennies and don’t invest in “better,” it’s tantamount to already having given up.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 3:51 pm on February 5, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , , , Particle Physics Is Doing Just Fine, ,   

    From slate.com: “Particle Physics Is Doing Just Fine” 

    SLATE

    From slate.com

    Jan 31, 2019
    Chanda Prescod-Weinstein
    Tim M.P. Tait


    CERN/ALICE Detector

    Research is a search through the unknown. If you knew the answer, there would be no need to do the research, and until you do the research, you don’t know the answer. Science is a complex social phenomenon, but certainly its history includes repeated episodes of people having ideas, trying experiments to test those ideas, and using the results to inform the next round of ideas. When an experimental result indicates that one particular idea is not correct, this is neither a failure of the experiment nor of the original idea itself; it’s an advancement of our understanding of the world around us.

    Recently, particle physics has become the target of a strange line of scientific criticism. Articles like Sabine Hossenfelder’s New York Times op-ed questioning the “uncertain future” of particle physics and Vox’s “The $22 Billion Gamble: Why Some Physicists Aren’t Excited About Building a Bigger Particle Collider” raise the specter of failed scientists. To read these articles, you’d think that unless particle physics comes home with a golden ticket in the form of a new particle, it shouldn’t come home at all. Or at least, it shouldn’t get a new shot at exploring the universe’s subatomic terrain. But the proposal that particle physicists are essentially setting money on fire comes with an insidious underlying message: that science is about the glory of discovery, rather than the joy of learning about the world. Finding out that there are no particles where we had hoped tells us about the distance between human imagination and the real world. It can operate as a motivation to expand our vision of what the real world is like at scales that are totally unintuitive. Not finding something is just as informative as finding something.

    That’s not to say resources should be infinite or to suggest that community consensus isn’t important. To the contrary, the particle physics community, like the astronomy and planetary science communities, takes the conversation about what our priorities should be so seriously that we have it every half decade or so. Right now, the European particle physics community is in the middle of a “strategy update,” and plans are underway for the U.S. particle physics community to hold the next of its “Snowmass community studies,” which take place approximately every five years. These events are opportunities to take stock of recent developments and to devise a strategy to maximize scientific progress in the field. In fact, we’d wager that they’re exactly what Hossenfelder is asking for when she suggests “it’s time for particle physicists to step back and reflect on the state of the field.”

    One of the interesting questions that both of these studies will confront is whether or not the field should prioritize construction of a new high-energy particle accelerator. In past decades, many resources have been directed toward the construction and operation of the Large Hadron Collider, a gigantic device whose tunnel spans two countries and whose budget is in the billions of dollars. Given funding constraints, it is entirely appropriate to ask whether it makes sense to prioritize a future particle accelerator at this moment in history. A new collider is likely to have a price tag measured in tens of billions of dollars and would represent a large investment—though not large compared with the scale of other areas of government spending, and the collider looks even less expensive when spread out over decades and shared by many nations.

    The LHC was designed to reach energies of 14 trillion electron volts, about seven times more than its predecessor, the Tevatron at Fermilab in Chicagoland.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    FNAL/Tevatron map

    FNAL/Tevatron

    There was very strong motivation to explore collisions at these energies; up until the LHC began operations, our understanding of the Standard Model of particle physics, the leading theory describing subatomic particles and their interactions, contained a gaping hole.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    The theory could only consistently describe the massive fundamental particles that are observed in our experiments if one included the Higgs boson—a particle that had yet to be observed.

    Self-consistency demanded that either the Higgs or something else providing masses would appear at the energies studied by the LHC. There were a host of competing theories, and only experimental data could hope to judge which one was realized in nature.

    So we tried it. And because the LHC allowed us to actually observe the Higgs, we now know that the picture in which masses arise from the Higgs is either correct or very close to being correct.

    Peter Higgs

    CERN CMS Higgs Event

    CERN ATLAS Higgs Event

    The LHC discovered a particle whose interactions with the known particles matches the predictions to within about 10 percent or so. This represents a triumph in our understanding of the fundamental building blocks of nature, one that would have been impossible without both 1) the theoretical projections that defined the characteristics that the Higgs must have to play its role and 2) the experimental design of the accelerator and particle detectors and the analysis of the data that they collected. In order to learn nature’s secrets, theory and experiment must come together.

    [I.E., you must do the math.]

    Some people have labeled the LHC a failure because even though it confirmed the Standard Model’s vision for how particles get their masses, it did not offer any concrete hint of any further new particles besides the Higgs. We understand the disappointment. Given the exciting new possibilities opened up by exploring energy levels we’ve never been privy to here on earth, this feeling is easy to relate to. But it is also selling the accomplishments short and fails to appreciate how research works. Theorists come up with fantastical ideas about what could be. Most of them are wrong, because the laws of physics are unchanging and universal. Experimentalists are taking on the task of actually popping open the hood and looking at what’s underneath it all. Sometimes, they may not find anything new.

    A curious species, we are left to ask more questions. Why did we find this and not that? What should we look for next? What a strange and fascinating universe we live in, and how wonderful to have the opportunity to learn about it.

    It cannot be ignored that if the U.S. had built the Superconducting Super Collider a particle accelerator complex under construction in the vicinity of Waxahachie, Texas, Higgs would have been found in the U.S. and High Energy Physics would not have been ceded to Europe.

    3
    Tracing the path of the particle accelerators and tunnels planned for the Superconducting Supercollider Project. You can see the main ring circling Waxahachie.

    The Superconducting Super Collider planned ring circumference was 87.1 kilometers (54.1 mi) with an energy of 20 TeV per proton and was set to be the world’s largest and most energetic. It would have greatly surpassed the current record held by the Large Hadron Collider which has ring circumference 27 km (17 mi) and energy of 13 TeV per proton. The project’s director was Roy Schwitters, a physicist at the University of Texas at Austin. Dr. Louis Ianniello served as its first Project Director for 15 months. The project was cancelled in 1993 due to budget problems [Congress cancelled the Collider for having “no immediate econmic value].

    See the full article here .
    See also the possible future of HEP here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Slate is a daily magazine on the Web. Founded in 1996, we are a general-interest publication offering analysis and commentary about politics, news, business, technology, and culture. Slate’s strong editorial voice and witty take on current events have been recognized with numerous awards, including the National Magazine Award for General Excellence Online. The site, which is owned by Graham Holdings Company, does not charge for access and is supported by advertising revenues.

     
  • richardmitnick 4:10 pm on January 30, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , Retired equipment lives on in new physics experiments,   

    From Symmetry: “Retired equipment lives on in new physics experiments” 

    Symmetry Mag
    From Symmetry

    01/30/19
    Emily Ayshford

    1
    Courtesy of CERN

    Physicists often find thrifty, ingenious ways to reuse equipment and resources.

    What do you do with 800 square feet of scintillator from an old physics experiment? Cut it up and give it to high schools to make cosmic ray detectors, of course.

    And what about an 800-ton magnet originally used to discover new particles? Send it off on a months-long journey via truck, train and ship halfway across the world to detect oscillating particles called neutrinos.

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment

    It’s all part of the vast recycling network of the physics community, where decommissioned experimental equipment and data are reused, re-analyzed and repurposed, giving expensive materials and old tapes of data second or even third lives—often in settings vastly different from their original homes.

    For physicists whose experiments can easily cost millions or even billions of dollars, such reuse is not just thrifty, it’s essential for building next-generation experiments.

    When experiments are shut down, “the vultures come knocking at your door,” jokes Jonathan Lewis, deputy head of the particle physics division at Department of Energy’s Fermi National Accelerator Laboratory. He was in charge of decommissioning the Collider Detector at Fermilab (CDF) experiment in 2011.

    FNAL/Tevatron CDF detector

    “You try to get the word out, but people in the community know what experiments are being shut down. They start to look to see what’s available.”

    Shipping magnets around the world

    Take, for example, the UA1 experiment magnet.

    2
    UA1 magnet sets off for a second new life – CERN

    Originally built in 1979, it was part of a particle detector at CERN that discovered the W and Z bosons. After that experiment shut down in 1990, it was used in the NOMAD neutrino experiment from 1995 to 1998.

    3
    The NOMAD Detector

    But then it sat outside at CERN, rusting a bit and waiting for its next home, which would ultimately be the T2K neutrino experiment in Japan.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan


    T2K Experiment, Tokai to Kamioka, Japan

    “Even with the amount of work needed to refurbish it, and the cost of transporting it, it was still worthwhile to reuse it,” says Chang Kee Jung, US principal investigator for the experiment and professor at Stony Brook University. “Usually when you are using old equipment, it’s like driving a used car. The parts aren’t new, so it will break down more often, and you will have more maintenance costs. But magnets generally have much longer lifetimes than other devices, since they are rather simple equipment.”

    In 2009, the magnet was dismantled, cleaned and polished. Most of it was then loaded up into 35 containers, which traveled by train to Antwerp before being loaded onto container ships bound for Japan. The magnet eventually reached the J-PARC facility north of Tokyo and became part of the T2K neutrino oscillation experiment.

    Japan Proton Accelerator Research Complex J-PARC, located in Tokai village, Ibaraki prefecture, on the east coast of Japan


    J-PARC Facility Japan Proton Accelerator Research Complex , located in Tokai village, Ibaraki prefecture, on the east coast of Japan

    Magnet reuse is common—even magnets from MRI scanners have been reused in physics experiments—but their special transportation often makes headlines. In 1979, Argonne National Laboratory sent a 107-ton superconducting magnet to what is now called SLAC National Accelerator Laboratory. Jung recalls stories about local news stations reporting on its 20-day journey via a special tractor-trailer, which took up two lanes of interstate highway while traveling 25 miles per hour. The Muon g-2 experiment at Fermi National Accelerator Laboratory in Illinois uses a giant magnet transported 3200 miles by land and sea from its original home at Brookhaven National Accelerator Laboratory in New York [above]. (That trip even had its own hashtag: #bigmove.)

    But magnets prove their worth. Even as the UA1 magnet nears its fifth decade, Jung imagines it still has a good decade worth of life left. “Second lives for equipment in physics are not unusual, but to have a third life like this is unusual,” he says. “This is probably the longest-used magnet.”

    Absorbing an old experiment into a new one

    Sometimes, entire detectors are absorbed from one experiment to another. That was the case with ICARUS, the first large-scale time projection liquid-argon neutrino detector. It started out at the Laboratori Nazionali del Gran Sasso in Italy to look for neutrino oscillations over a long baseline, then was transported to CERN for refurbishment and then to Fermilab in 2017. There, it will join the lab’s program to search for sterile neutrinos, which could help solve questions about the origin of our universe. The detector survived a complex journey, traveling thousands of miles via truck and barge. (Hashtag: #IcarusTrip.)

    INFN Gran Sasso ICARUS, since moved to FNAL

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

    FNAL/ICARUS

    Reusing mines, battleships

    Physics experiments don’t just reuse their own equipment—they also often give second lives to non-scientific facilities and resources. Old mines, with their hollowed-out underground sites shielded from cosmic rays, have been the sites of countless physics experiments. The Homestake Mine in South Dakota houses several experiments, including the Majorana Demonstrator, LUX dark matter experiment, and the upcoming Deep Underground Neutrino Experiment.


    U Washington Majorana Demonstrator Experiment at SURF

    U Washington Large Underground Xenon at SURF, Lead, SD, USA


    Being replaced with

    LBNL LZ project at SURF, Lead, SD, USA

    The Mozumi Mine in Japan has been home to many experiments, including the Super-Kamiokande, and a set of experiments (KamiokaNDE, KamLAND, and KamLAND-Zen) that have all re-used the same neutrino detector.

    Super-Kamiokande experiment. located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    Hyper-Kamiokande, a neutrino physics laboratory located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.

    KamLAND at the Kamioka Observatory in located in a mine in Hida, Japan


    KamLAND at the Kamioka Observatory in located in a mine in Hida, Japan

    KamLAND-Zen detector, an electron antineutrino detector at the Kamioka Observatory, an underground neutrino detection facility near Toyama, Japan

    Other resources have found new life in physics experiments: the Sudbury Neutrino Observatory in Canada, for example, once borrowed 1000 tons of heavy water from Canadian nuclear reactors to use in a neutrino detector.

    Sudbury Neutrino Observatory, , no longer operating

    And the CDF experiment, which studied high energy proton-antiproton collisions at Fermilab’s Tevatron collider, was partially constructed using steel from decommissioned battleships.

    FNAL/Tevatron map


    FNAL/Tevatron CDF detector

    That experiment ultimately paid it forward by disassembling and sharing a long list of experimental equipment after it was shut down in 2011. Lewis can cite where everything went: phototubes to India, electronics to Italy, computer servers to South Korea. Here in the United States, Brookhaven National Laboratory and Jefferson Lab got hundreds of phototubes for nuclear physics experiments, and 1000 tons of the old battleship steel will be used as shielding for the Long-Baseline Neutrino Facility target.

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

    The 800 square feet of scintillator was sent to QuarkNet, an educational program, to be used as cosmic ray detectors for high schools.

    “All that’s left is the magnet and a few detector pieces that are on display,” he says. “And a legacy of over 700 papers and lots of memories. In fact, people are still doing analysis on the data.”

    Revisiting old data anew

    Data can be analyzed and looked at anew for years to come.

    That’s the case for DZero, the other experiment on the Tevatron at Fermilab that ran from 1992 to 2011.

    FNAL/Tevatron DZero

    In its heyday, the experiment revealed particles like the top quark. Though it shut down soon after the start of the Large Hadron Collider, scientists have data from about 10 billion events that still have a story to tell. Dozens of papers from that data have been published in the last six years.

    “They are probably not Nobel Prize-winning measurements, but they are very important for understanding specific areas in particle physics,” says Dmitri Denisov, a distinguished scientist at Fermilab and spokesperson for the DZero experiment. For example, the data has been important in searching for exotic particles, a field that did not become popular until after the Tevatron shut down.

    From experiment to education

    Perhaps one of the most inspirational ways for experiments to live second lives is as educational displays. The DZero experiment was left mostly intact, and now thousands of visitors per year can stand right next to a four-story particle detector Fermilab scientists used to discover the top quark.

    Denisov sometimes leads tours of high school students through the control room, where computer screens still look as though they are taking data. “You can see how excited the students are,” he says. “It shows them the joy of complex particle physics experiments. That’s probably the best second life that none of us expected.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 11:46 am on January 29, 2019 Permalink | Reply
    Tags: Accelerator Science, Fermilab scientists help push AI to unprecedented speeds, , , , ,   

    From Fermi National Accelerator Lab: “Fermilab scientists help push AI to unprecedented speeds” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    January 29, 2019

    Javier Duarte
    Sergo Jindariani
    Ben Kreis
    Nhan Tran

    1
    Researchers at Fermilab are taking cues from industry to improve their own “big data” processing challenges.

    Machine learning is revolutionizing data analysis across academia and industries and is having an impact on our daily lives. Recent leaps in driverless car navigation and the voice recognition features of personal assistants are possible because of this form of artificial intelligence. As data sets in the Information Age continue to grow, companies such as Google and Microsoft are building tools that make machine learning faster and more efficient.

    Researchers at Fermilab are taking cues from industry to improve their own “big data” processing challenges.

    Data sets in particle physics are growing at unprecedented rates as accelerators are upgraded to higher performance and detectors become more fine-grained and complex. More sophisticated methods for analyzing these large data sets that also avoid losses in computing efficiency are required. For well over two decades, machine learning has already proven to be useful in a wide range of particle physics applications.

    To fully exploit the power of modern machine learning algorithms, Fermilab CMS scientists are preparing to deploy these algorithms in the first level of data filtering in their experiment, that is, in the “trigger.”

    CERN/CMS

    In particle physics lingo, a trigger occurs when a series of electronics and algorithms are used to select which collisions are recorded and which are discarded.

    Fermilab scientists are exploring a new approach that uses high-throughput, low-latency programmable microchips called field programmable gate arrays (FPGAs). The trigger algorithms have to operate in a daunting environment, which requires them to process events at the collision rate of 40 MHz at the Large Hadron Collider (LHC) and complete it in as little as hundreds of nanoseconds.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    In a growing collaboration with CERN, MIT, University of Florida, University of Illinois at Chicago and other institutions, Fermilab researchers have recently developed a software tool, called hls4ml, that helps users implement their own custom machine learning algorithms on FPGAs. hls4ml translates industry-standard machine learning algorithms, such as Keras, TensorFlow and PyTorch, into instructions for the FPGA, called firmware. This tool leverages a new way to create firmware called high-level synthesis (HLS), which is similar to writing standard software and reduces development time. hls4ml also allows users to take advantage of the capabilities of FPGAs to speed up computations, such as the ability to do many multiplications in parallel with reduced (but sufficient) precision.

    The first proof-of-concept implementation of the tool showed that a neural network with over 100 hidden neurons could classify jets originating from different particles, such as quarks, gluons, W bosons, Z bosons or top quarks, in under 75 nanoseconds. Neural networks can also be used for iterative tasks, such as determining the momentum of a muon passing through the CMS endcap detectors. Using hls4ml, CMS collaborators have shown that the ability to reject fake muons was up to 80 percent better than previous methods.

    Ultrafast, low-latency machine learning inference in FPGA hardware has much broader implications. Beyond real-time LHC data processing, applications can be found in neutrino and dark matter experiments and particle accelerator beamline controls. Even more broadly, accelerating machine learning with specialized hardware such as FPGAs and dedicated circuits called ASICs (application-specific integrated circuits) is an area of active development for large-scale computing challenges. Industry drivers such as Amazon Web Services with Xilinx FPGAs, Microsoft Azure and Intel have invested heavily in FPGAs, while Google has developed its own ASIC (a tensor processing unit, TPU). Specialized hardware platforms coupled with CPUs, referred to as co-processors, are driving the heterogeneous computing revolution. hls4ml can be applied in such co-processor platforms. Combining heterogeneous computing and hls4ML for low-latency machine learning inference could lead to an exciting potential to solve future computing challenges in particle physics.

    The authors are members of the Fermilab CMS Department.

    See the full article here .


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    Please help promote STEM in your local schools.

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    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.


    FNAL/MINERvA

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL Minos Far Detector

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

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
  • richardmitnick 9:26 am on January 29, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , ,   

    From CERN: “Colliders join the hunt for dark energy” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    From CERN

    24 January 2019

    1
    Dark analysis

    It is 20 years since the discovery that the expansion of the universe is accelerating, yet physicists still know precious little about the underlying cause. In a classical universe with no quantum effects, the cosmic acceleration can be explained by a constant that appears in Einstein’s equations of general relativity, albeit one with a vanishingly small value. But clearly our universe obeys quantum mechanics, and the ability of particles to fluctuate in and out of existence at all points in space leads to a prediction for Einstein’s cosmological constant that is 120 orders of magnitude larger than observed. “It implies that at least one, and likely both, of general relativity and quantum mechanics must be fundamentally modified,” says Clare Burrage, a theorist at the University of Nottingham in the UK.

    With no clear alternative theory available, all attempts to explain the cosmic acceleration introduce a new entity called dark energy (DE) that makes up 70% of the total mass-energy content of the universe.

    Dark energy depiction. Image: Volker Springle/Max Planck Institute for Astrophysics/SP)

    It is not clear whether DE is due to a new scalar particle or a modification of gravity, or whether it is constant or dynamic. It’s not even clear whether it interacts with other fundamental particles or not, says Burrage. Since DE affects the expansion of space–time, however, its effects are imprinted on astronomical observables such as the cosmic microwave background and the growth rate of galaxies, and the main approach to detecting DE involves looking for possible deviations from general relativity on cosmological scales.

    Unique environment

    Collider experiments offer a unique environment in which to search for the direct production of DE particles, since they are sensitive to a multitude of signatures and therefore to a wider array of possible DE interactions with matter. Like other signals of new physics, DE (if accessible at small scales) could manifest itself in high-energy particle collisions either through direct production or via modifications of electroweak observables induced by virtual DE particles.

    Last year, the ATLAS collaboration at the LHC [below]carried out a first collider search for light scalar particles that could contribute to the accelerating expansion of the universe. The results demonstrate the ability of collider experiments to access new regions of parameter space and provide complementary information to cosmological probes.

    Unlike dark matter, for which there exists many new-physics models to guide searches at collider experiments, few such frameworks exist that describe the interaction between DE and Standard Model (SM) particles.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    However, theorists have made progress by allowing the properties of the prospective DE particle and the strength of the force that it transmits to vary with the environment. This effective-field-theory approach integrates out the unknown microscopic dynamics of the DE interactions.

    The new ATLAS search was motivated by a 2016 model by Philippe Brax of the Université Paris-Saclay, Burrage, Christoph Englert of the University of Glasgow, and Michael Spannowsky of Durham University. The model provides the most general framework for describing DE theories with a scalar field and contains as subsets many well-known specific DE models – such as quintessence, galileon, chameleon and symmetron. It extends the SM lagrangian with a set of higher dimensional operators encoding the different couplings between DE and SM particles. These operators are suppressed by a characteristic energy scale, and the goal of experiments is to pinpoint this energy for the different DE–SM couplings. Two representative operators predict that DE couples preferentially to either very massive particles like the top quark (“conformal” coupling) or to final states with high-momentum transfers, such as those involving high-energy jets (“disformal” coupling).

    Signatures

    “In a big class of these operators the DE particle cannot decay inside the detector, therefore leaving a missing energy signature,” explains Spyridon Argyropoulos of the University of Iowa, who is a member of the ATLAS team that carried out the analysis. “Two possible signatures for the detection of DE are therefore the production of a pair of top-anti­top quarks or the production of high-energy jets, associated with large missing energy. Such signatures are similar to the ones expected by the production of supersymmetric top quarks (“stops”), where the missing energy would be due to the neutralinos from the stop decays or from the production of SM particles in association with dark-matter particles, which also leave a missing energy signature in the detector.”

    The ATLAS analysis, which was based on 13 TeV LHC data corresponding to an integrated luminosity of 36.1 fb–1, re-interprets the result of recent ATLAS searches for stop quarks and dark matter produced in association with jets. No significant excess over the predicted background was observed, setting the most stringent constraints on the suppression scale of conformal and disformal couplings of DE to normal matter in the context of an effective field theory of DE. The results show that the characteristic energy scale must be higher than approximately 300 GeV for the conformal coupling and above 1.2 TeV for the disformal coupling.

    The search for DE at colliders is only at the beginning, says Argyropoulos. “The limits on the disformal coupling are several orders of magnitudes higher than the limits obtained from other laboratory experiments and cosmological probes, proving that colliders can provide crucial information for understanding the nature of DE. More experimental signatures and more types of coupling between DE and normal matter have to be explored and more optimal search strategies could be developed.”

    With this pioneering interpretation of a collider search in terms of dark-energy models, ATLAS has become the first experiment to probe all forms of matter in the observable universe, opening a new avenue of research at the interface of particle physics and cosmology. A complementary laboratory measurement is also being pursued by CERN’s CAST experiment [below], which studies a particular incarnation of DE (chameleon) produced via interactions of DE with photons.

    But DE is not going to give up its secrets easily, cautions theoretical cosmologist Dragan Huterer at the University of Michigan in the US. “Dark energy is normally considered a very large-scale phenomenon, but you may justifiably ask how the study of small systems in a collider can say anything about DE. Perhaps it can, but in a fairly model-dependent way. If ATLAS finds a signal that departs from the SM prediction it would be very exciting. But linking it firmly to DE would require follow-up work and measurements – all of which would be very exciting to see happen.”

    LHC signatures of scalar dark energy
    https://journals.aps.org/prd/abstract/10.1103/PhysRevD.94.084054

    See the full article here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New
    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN map

    CERN LHC Grand Tunnel

    CERN LHC particles

    OTHER PROJECTS AT CERN

    CERN AEGIS

    CERN ALPHA

    CERN ALPHA


    CERN ALPHA-g Detector

    CERN ALPHA-g Detector


    CERN AMS

    CERN ACACUSA

    CERN ASACUSA

    CERN ATRAP

    CERN ATRAP

    CERN AWAKE

    CERN AWAKE

    CERN CAST

    CERN CAST Axion Solar Telescope

    CERN CLOUD

    CERN CLOUD

    CERN COMPASS

    CERN COMPASS

    CERN DIRAC

    CERN DIRAC

    CERN GBAR

    CERN GBAR

    CERN ISOLDE

    CERN ISOLDE

    CERN LHCf

    CERN LHCf

    CERN NA62

    CERN NA62

    CERN NTOF

    CERN TOTEM

    CERN UA9

    CERN Proto Dune

    CERN Proto Dune

     
  • richardmitnick 1:15 pm on January 25, 2019 Permalink | Reply
    Tags: Accelerator Science, , , , , , , , Wish list of particle colliders   

    From The New York Times- “Opinion: The Uncertain Future of Particle Physics” 

    New York Times

    From The New York Times

    Jan. 23, 2019
    Sabine Hossenfelder

    Ten years in, the Large Hadron Collider has failed to deliver the exciting discoveries that scientists promised.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    The Large Hadron Collider is the world’s largest particle accelerator. It’s a 16-mile-long underground ring, located at CERN in Geneva, in which protons collide at almost the speed of light. With a $5 billion price tag and a $1 billion annual operation cost, the L.H.C. is the most expensive instrument ever built — and that’s even though it reuses the tunnel of an earlier collider.

    CERN Large Electron Positron Collider

    The L.H.C. has collected data since September 2008. Last month, the second experimental run completed, and the collider will be shut down for the next two years for scheduled upgrades. With the L.H.C. on hiatus, particle physicists are already making plans to build an even larger collider. Last week, CERN unveiled plans to build an accelerator that is larger and far more powerful than the L.H.C. — and would cost over $10 billion.

    CERN FCC Future Circular Collider map

    I used to be a particle physicist. For my Ph.D. thesis, I did L.H.C. predictions, and while I have stopped working in the field, I still believe that slamming particles into one another is the most promising route to understanding what matter is made of and how it holds together. But $10 billion is a hefty price tag. And I’m not sure it’s worth it.

    In 2012, experiments at the L.H.C. confirmed the discovery of the Higgs boson — a prediction that dates back to the 1960s — and it remains the only discovery made at the L.H.C.

    Peter Higgs

    CERN CMS Higgs Event

    CERN ATLAS Higgs Event

    Particle physicists are quick to emphasize that they have learned other things: For example, they now have better knowledge about the structure of the proton, and they’ve seen new (albeit unstable) composite particles. But let’s be honest: It’s disappointing.

    Before the L.H.C. started operation, particle physicists had more exciting predictions than that. They thought that other new particles would also appear near the energy at which the Higgs boson could be produced. They also thought that the L.H.C. would see evidence for new dimensions of space. They further hoped that this mammoth collider would deliver clues about the nature of dark matter (which astrophysicists think constitutes 85 percent of the matter in the universe) or about a unified force.

    The stories about new particles, dark matter and additional dimensions were repeated in countless media outlets from before the launch of the L.H.C. until a few years ago. What happened to those predictions? The simple answer is this: Those predictions were wrong — that much is now clear.

    The trouble is, a “prediction” in particle physics is today little more than guesswork. (In case you were wondering, yes, that’s exactly why I left the field.) In the past 30 years, particle physicists have produced thousands of theories whose mathematics they can design to “predict” pretty much anything. For example, in 2015 when a statistical fluctuation in the L.H.C. data looked like it might be a new particle, physicists produced more than 500 papers in eight months to explain what later turned out to be merely noise. The same has happened many other times for similar fluctuations, demonstrating how worthless those predictions are.

    To date, particle physicists have no reliable prediction that there should be anything new to find until about 15 orders of magnitude above the currently accessible energies. And the only reliable prediction they had for the L.H.C. was that of the Higgs boson. Unfortunately, particle physicists have not been very forthcoming with this information. Last year, Nigel Lockyer, the director of Fermilab, told the BBC, “From a simple calculation of the Higgs’ mass, there has to be new science.” This “simple calculation” is what predicted that the L.H.C. should already have seen new science.

    I recently came across a promotional video for the Future Circular Collider that physicists have proposed to build at CERN. This video, which is hosted on the CERN website, advertises the planned machine as a test for dark matter and as a probe for the origin of the universe. It is extremely misleading: Yes, it is possible that a new collider finds a particle that makes up dark matter, but there is no particular reason to think it will. And such a machine will not tell us anything about the origin of the universe. Paola Catapano, head of audiovisual productions at CERN, informed me that this video “is obviously addressed to politicians and not fellow physicists and uses the same arguments as those used to promote the L.H.C. in the ’90s.”

    But big science experiments are investments in our future. Decisions about what to fund should be based on facts, not on shiny advertising. For this, we need to know when a prediction is just a guess. And if particle physicists have only guesses, maybe we should wait until they have better reasons for why a larger collider might find something new.

    It is correct that some technological developments, like strong magnets, benefit from these particle colliders and that particle physics positively contributes to scientific education in general. These are worthy investments, but if that’s what you want to spend money on, you don’t also need to dig a tunnel.

    And there are other avenues to pursue. For example, the astrophysical observations pointing toward dark matter should be explored further; better understanding those observations would help us make more reliable predictions about whether a larger collider can produce the dark matter particle — if it even is a particle.

    There are also medium-scale experiments that tend to fall off the table because giant projects eat up money. One important medium-scale project is the interface between the quantum realm and gravity, which is now accessible to experimental testing. Another place where discoveries could be waiting is in the foundations of quantum mechanics. These could have major technological impacts.

    Now that the L.H.C. is being upgraded and particle physics experiments at the detector are taking a break, it’s time for particle physicists to step back and reflect on the state of the field. It’s time for them to ask why none of the exciting predictions they promised have resulted in discoveries. Money will not solve this problem. And neither will a larger particle collider.

    See the full article here .

    See also From Science News: “Physicists aim to outdo the LHC with this wish list of particle colliders

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
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