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  • richardmitnick 10:57 am on September 23, 2016 Permalink | Reply
    Tags: , , , , Particle Physics, , Vox,   

    From Yale via Vox: “Why physicists really, really want to find a new subatomic particle” 

    Yale University bloc

    Yale University

    1

    Vox

    Sep 21, 2016
    Brian Resnick

    The latest search for a new particle has fizzled. Scientists are excited, and a bit scared.

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    Particle physicists are begging nature to reveal the secrets of the universe. The universe isn’t talking back. FABRICE COFFRINI/AFP/Getty Images

    Particle physicists are rather philosophical when describing their work.

    “Whatever we find out, that is what nature chose,” Kyle Cranmer, a physics professor at New York University, tells me. It’s a good attitude to have when your field yields great disappointments.

    For months, evidence was mounting that the Large Hadron Collider, the biggest and most powerful particle accelerator in the world, had found something extraordinary: a new subatomic particle, which would be a discovery surpassing even the LHC’s discovery of the Higgs boson in 2012, and perhaps the most significant advance since Einstein’s theory of relativity.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    And yet, nature had other plans.

    In August, the European Organization for Nuclear Research (CERN) reported that the evidence for the new particle had run thin. What looked like a promising “bump” in the data, indicating the presence of a particle with a unique mass, was just noise.

    But to Cranmer — who has analyzed LHC data in his work — the news did not equate failure. “You have to keep that in mind,” he says. “Because it can feel that way. It wasn’t there to be discovered. It’s like being mad that someone didn’t find an island when someone is sailing in the middle of the ocean.”

    What’s more, the LHC’s journey is far from over. The machine is expected to run for another 20 or so years. There will be more islands to look for.

    “We’re either going to discover a bunch of new particles or we will not,” Cranmer says. “If we find new particles, we can study them, and then we have a foothold to make progress. And if we don’t, then [we’ll be] staring at a flat wall in front figuring out how to climb it.”

    This is a dramatic moment, one that could provoke “a crisis at the edge of physics,” according to a New York Times op-ed. Because if the superlative LHC can’t find answers, it will cast doubt that answers can be found experimentally.

    From here, there are two broad scenarios that could play out, both of which will vastly increase our understanding of nature. One scenario will open up physics to a new world of understanding about the universe; the other could end particle physics as we know it.

    The physicists themselves can’t control the outcome. They’re waiting for nature to tell them the answers.

    Why do we care about new subatomic particles anyway?

    3
    A graphic showing traces of collision of particles at the Compact Muon Solenoid (CMS) experience is pictured with a slow speed experience at Universe of Particles exhibition of the the European Organization for Nuclear Research (CERN) on December 13, 2011, in Geneva. FABRICE COFFRINI/AFP/GettyImages

    The LHC works by smashing together atoms at incredibly high velocities. These particles fuse and can form any number of particles that were around in the universe from the Big Bang onward.

    When the Higgs boson was confirmed in 2012, it was a cause for celebration and unease.

    CERN CMS Higgs Event
    CERN CMS Higgs Event

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    The Higgs was the last piece of a puzzle called the standard model, which is a theory that connects all the known components of nature (except gravity) together in a balanced, mathematical equation.

    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 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 Higgs was the final piece that had been theorized to exist but never seen.

    After the Higgs discovery, the scientists at the LHC turned their hopes in a new direction. They hoped the accelerator could begin to find particles that had never been theorized nor ever seen. It was like going from a treasure hunt with a map to chartering a new ocean.

    They want to find these new subatomic particles because even though the standard model is now complete, it still can’t answer a lot of lingering questions about the universe. Let’s go through the two scenarios step by step.

    Scenario 1: There are more subatomic particles! Exciting!

    If the LHC finds new subatomic particles, it lend evidence to a theory known as supersymmetry. Supersymmetry posits that all the particles in the standard model must have a shadow “super partner” that spins in a slightly different direction.

    Standard model of Supersymmetry DESY
    Standard model of Supersymmetry DESY

    Scientists have never seen one of these supersymmetrical particles, but they’re keen to. Supersymmetry could neatly solve some of the biggest problems vexing physicists right now.

    Such as:

    1) No one knows what dark matter is

    One of these particles could be what scientists call “dark matter,” which is theorized to make up 27 percent of the universe. But we’ve never seen dark matter, and that leaves a huge gaping hole in our understanding of the how the universe formed and exists today.

    “It could be that one particle is responsible for dark matter,” Cranmer explains. Simple enough.

    2) The Higgs boson is much too light

    The Higgs discovery was an incredible triumph, but it also contained a mystery to solve. The boson — at 126 GeV (giga electron volts) — was much lighter than the standard model and the math of quantum mechanics suggests it should be.

    Why is that a problem? Because it’s a wrinkle to be ironed out in our understanding of the universe. It suggests the standard model can’t explain everything. And physicists want to know everything.

    “Either nature is sort of ugly, which is entirely conceivable, and we just have to live with the fact that the Higgs boson mass is light and we don’t know why,” Ray Brock, a Michigan State University physicist who has worked on the LHC, says, “or nature is trying to tell us something.”

    It could be that a yet-to-be-discovered subatomic particle interacts with the Higgs, making it lighter than it ought to be.

    3) The standard model doesn’t unify the forces of the universe

    There are four major forces that make the universe tick: the strong nuclear force (which holds atoms together), the weak nuclear force (what makes Geiger counters tick), electromagnetism (you’re using it right now, reading this article on an electronic screen), and gravity (don’t look down.)

    Scientists aren’t content with the four forces. They, for decades, have been trying to prove that the universe works more elegantly, that, deep down, all these forces are just manifestations of one great force that permeates the universe.

    Physicists call this unification, and the standard model doesn’t provide it.

    “If we find supersymmetry at the LHC, it is a huge boost to the dream that three of the fundamental forces we have [all of them except gravity] are all going to unify,” Cranmer says.

    4) Supersymmetry would lead to more particle hunting

    If scientists find one new particle, supersymmetry means they’ll find many more. That’s exciting. “It’s not going to be just one new particle that we discovered, and yay!” Cranmer says. “We’re going to be finding new forces, or learn something really deep about the nature of space and time. Whatever it is, it’s going to be huge.”

    Scenario 2: There are no new subatomic particles. Less exciting! But still interesting. And troubling.

    The LHC is going to run for around another 20 years, at least. There’s a lot of time left to find new particles, even if there is no supersymmetry. “This is what always blows my mind,” Brock says. “We’ve only taken about 5 percent of the total planned data that the LHC is going to deliver until the middle 2020s.”

    But the accelerator also might not find anything. If the new particles aren’t there to find, the LHC won’t find them. (Hence, the notion that physicists are looking for “what nature chose.”)

    But again, this doesn’t represent a failure. It will actually yield new insights about the universe.

    “It would be a profound discovery to find that we’re not going to see anything else,” Cranmer says.

    1) For one, it would suggest that supersymmetry isn’t the answer

    If supersymmetry is dead, then theoretical physicists will have to go back to the drawing board to figure out how to solve the mysteries left open by the standard model.

    “If we’re all coming up empty, we would have to question our fundamental assumptions,” Sarah Demers, a Yale physicist, tells me. “Which is something we’re trying to do all the time, but that would really force us.”

    2) The answers exist, but they exist in a different universe

    If the LHC can’t find answers to questions like “why is the Higgs so light?” scientists might grow to accept a more out-of-the-box idea: the multiverse.

    That’s the idea where there are tons of universes all existing parallel to one another. It could be that “in most of [the universes], the Higgs boson is really heavy, and in only in very unusual universes [like our own] is the Higgs boson so light that life can form,” Cranmer says.

    Basically: On the scale of our single universe, it might not make sense for the Higgs to be light. But if you put it together with all the other possible universes, the math might check out.

    There’s a problem with this theory, however: If heavier Higgs bosons exist in different universes, there’s no possible way to observe them. They’re in different universes!

    “Which is why a lot of people hate it, because they consider it to be anti-science,” Cranmer says. “It might be impossible to test.”

    3) The new subatomic particles do exist, but the LHC isn’t powerful enough to find them

    In 20 years, if the LHC doesn’t find any new particles, there might be a simple reason: These particles are too heavy for the LHC to detect.

    This is basic E=mc2 Einstein: The more energy in the particle accelerator, the heavier the particles it can create. The LHC is the most powerful particle accelerator in the history of man, but even it has its limits.

    So what will physicists do? Build an even bigger, even smashier particle collider? That’s an option. There are currently preliminary plans in China for a collider double the size of the LHC.

    Building a bigger collider might be a harder sell for international funding agencies. The LHC was funded in part because of the quest to confirm the Higgs. Will governments really spend billions on a machine that may not yield epic insights?

    “Maybe we were blessed as a field that we always had a target or two to shoot for. We don’t have that anymore,” says Markus Klute, an MIT physicist stationed at CERN in Europe. “It’s easier to explain to the funding agencies specifically that there’s a specific endpoint.”

    The LHC will keep running for the foreseeable future. But it could prove a harder task to make the case to build a new collider.

    Either way, these are exciting times for physics

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    Dean Mouhtaropoulos/Getty Images

    “I think we have had a tendency to be prematurely depressed,” Demers says. “It’s never a step backward to learn something new,” even if the news is negative. “Ruling out ideas teaches us an incredible amount.”

    And she says that even if the LHC can never find another particle, it can still produce meaningful insights. Already, her colleagues are using it to help determine why there’s so much more matter than antimatter in the universe. And she reminds me the LHC can still teach us more about the mysterious Higgs. We will be able to measure it to a more precise degree.

    Brock, the MSU physicist, notes that since the 1960s, physicists have been chasing the standard model. Now they don’t quite know what they’re chasing. But they know it will change the world.

    “I can’t honestly say in all those 40 years, I’ve been exploring,” Brock says. “I’ve been testing the standard model. The Higgs boson was the last missing piece. Now, we have to explore.”

    See the full article here .

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    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 2:42 pm on September 20, 2016 Permalink | Reply
    Tags: , CERN SCOAP3, , , Particle Physics   

    From CERN: “Global open access initiative, SCOAP3, set to continue” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    20 Sep 2016
    Harriet Kim Jarlett

    1
    After three years of successful operation and growth, CERN announces continuation of global SCOAP3 Open Access initiative for another three (Image: Maximilian Brice/ CERN)

    After three years of successful operation and growth, CERN announced today the continuation of the global SCOAP3 Open Access initiative for at least three more years. SCOAP3, the Sponsoring Consortium for Open Access Publishing in Particle Physics, is an innovative partnership of over 3 000 libraries, funding agencies and research organisations from 44 countries. It has made tens of thousands of scientific articles freely available to everyone, with neither cost nor barrier for any author worldwide.

    “It is in the spirit of CERN’s Convention, and in the culture of our discipline, to make research results fully and freely available to everyone,” said CERN Director-General Fabiola Gianotti. “SCOAP3 allows everybody in the world to access high-quality scientific knowledge in peer-reviewed particle physics journals. CERN will continue to be fully engaged in such a vital initiative.”

    In cooperation with leading scientific publishers and learned societies, SCOAP3 has supported the transition to Open Access of key journals in the field of High-Energy Physics since 2014. In the first three years of SCOAP3 operation, 20 000 scientists from 100 countries have benefited from the opportunity to publish more than 13 000 Open Access articles free of charge.

    Hosted at CERN, under the oversight of international governance, SCOAP3 is primarily funded through the re-direction of budgets previously used by libraries to purchase journal subscriptions, to instead support Open Access publications. Funding Agencies in some research-intensive countries provide some additional support.

    Following the success of the first three years, the growth of the SCOAP3 partnership, and the increasing policy requirements for, and global commitment to, Open Access, CERN has now signed contracts with 10 scientific publishers and learned societies for a three-year extension of the initiative, from January 2017 to December 2019.

    “With its success, SCOAP3 has shown that its model of global cooperation is sustainable, in the same broad and participative way we build and operate large collaborations in particle physics,” said CERN Director for Research and Computing, Eckhard Elsen. “As a scientist I am impressed by how SCOAP3 partners played a pioneering role in advancing Open Access and I look forward to even larger partnership in the upcoming years.”

    See the full article here.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 10:39 am on September 20, 2016 Permalink | Reply
    Tags: , , , , Luminosity vs. Energy, , Particle Physics   

    From Don Lincoln at FNAL- “Accelerator Science: Luminosity vs. Energy” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Sep 19, 2016

    FNAL Don Lincoln
    Don Lincoln

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    In the world of high energy physics there are several parameters that are important when one constructs a particle accelerator. Two crucial ones are the energy of the beam and the luminosity, which is another word for the number of particles in the beam. In this video, Fermilab’s Dr. Don Lincoln explains the differences and the pros and cons. He even works in an unexpected sporting event.

    Watch, enjoy, learn.

    See the full article here .

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    Fermilab Campus

    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.

     
  • richardmitnick 9:16 am on September 9, 2016 Permalink | Reply
    Tags: , , CERN DIRAC, , Particle Physics   

    From Physics: “Synopsis: Strange Mesonic Atoms Detected” 

    Physics LogoAbout Physics

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    Physics

    September 8, 2016
    Michael Schirber

    1
    DIRAC Collaboration, Phys. Rev. Lett. (2016)

    1
    The Dimeson Relativistic Atom Complex (DIRAC) is an experiment to help physicists gain a deeper insight into the fundamental force called the strong force. CERN

    An atom is normally a nucleus surrounded by electrons. But physicists have observed several exotic atoms comprising other particles, such as mesons (two-quark particles). Following earlier hints, a new analysis of data from the DIRAC experiment at CERN finds the first conclusive evidence of an atom made up of a π meson (containing up and down quarks) and a K meson (containing up and strange quarks). Further study of these strange dimesons should give insight into how quarks interact at relatively low energies.

    Meson-containing atoms, such as kaonic hydrogen (proton plus K) and pionium (two oppositely charged π mesons), are bound together by electromagnetic forces. However, strong force interactions between quarks cause the atoms to decay. Precise measurements of these decay lifetimes would place important constraints on the probabilities of low-energy quark scattering, which cannot be calculated directly.

    The DIRAC experiment was built to detect and characterize πK atoms (as well as ππ atoms). To create these bound states, the researchers fire a high-energy proton beam into a thin metal sheet. Collisions between protons and metal nuclei occasionally produce πK atoms, and some of these atoms collide with other nuclei, causing them to dissociate into unbound πK pairs. DIRAC is designed to detect these pairs using a double-arm mass spectrometer. Previous results showed evidence of πK atoms, but the underlying statistical significance was too low to claim a detection. The DIRAC collaboration has now combined data from trials using different metal sheets and has improved estimates of the background from πK pairs unrelated to atoms. The team reports the detection of over 300 πK atoms. Additional analysis is continuing to extract the lifetime of the πK decay.

    This research is published in Physical Review Letters.

    See the full article here .

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
  • richardmitnick 9:19 am on September 8, 2016 Permalink | Reply
    Tags: , Electrophobic scalar boson, Particle Physics, , Possible new particle,   

    From U Washington via phys.org: “Hypothetical new particle could solve two major problems in particle physics” 

    U Washington

    University of Washington

    physdotorg
    phys.org

    September 8, 2016
    Lisa Zyga

    1
    Using constraints from previous experiments, the physicists identified two regions, A and B (dotted), to search for the new particle in proposed experiments. Credit: Liu et al. ©2016 American Physical Society

    Although the Large Hadron Collider’s enormous 13 TeV energy is more than sufficient to detect many particles that theorists have predicted to exist, no new particles have been discovered since the Higgs boson in 2012. While the absence of new particles is informative in itself, many physicists are still yearning for some hint of “new physics,” or physics beyond the standard model.

    In a new paper published in Physical Review Letters, physicists Yu-Sheng Liu, David McKeen, and Gerald A. Miller at the University of Washington in Seattle have hypothesized the existence of a new particle that looks very enticing because it could simultaneously solve two important problems: the proton radius puzzle and a discrepancy in muon anomalous magnetic moment measurements that differ significantly from standard model predictions.

    “The new particle can account for two seemingly unrelated problems,” Miller told Phys.org. “We also point out several experiments that can further test our hypothesis.”

    The physicists describe the hypothetical new particle as an “electrophobic scalar boson.” Currently there are five bosons in the standard model, only one of which is a scalar (the Higgs), meaning it has zero spin. All five bosons have been experimentally confirmed, and all are force carriers that play a role in holding matter together.

    One of the distinct features of the new hypothetical particle is that, although it is predicted to bind to protons and neutrons, it would bind very weakly or not at all to electrons, making it “electrophobic.” The scientists showed that this electrophobic property would allow the particle to solve both the proton and muon problems.

    In the proton radius puzzle, the problem is that the proton radius seems to have a different size depending on what type of particle is orbiting it. Experiments have found that the proton radius is slightly larger when it is orbited by an electron than when it is orbited by a muon, which is identical to the electron except for being 200 times heavier. Assuming that the discrepancy is not due to measurement error (which it very well may be, considering how difficult it is to measure a particle that is less than a femtometer [10-15 meters] across), the results may point to the existence of a previously unknown fundamental force that pulls protons and muons closer together, but does not act between protons and electrons.

    “The principle of lepton universality is a pillar of the standard model,” Miller said, referring to the idea that all leptons, including electrons and muons, should behave in the same way. “Our particle violates this principle, because interactions with muons and electrons are different.”

    The second problem involves the muon’s anomalous magnetic moment, which is a measure of how quantum effects contribute to the magnetic moment of a particle. So far, the most precise measurement disagrees with the standard model by more than three standard deviations. Once again, physicists think that the discrepancy may indicate physics beyond the standard model, or else more accurate measurements are needed. If the answer is new physics, then the new particle suggests that the proton and muon problems may be related.

    “The proton radius puzzle can be explained if there is a new additional attractive interaction between the muon and proton,” Miller said. “Such an interaction must also contribute to the muon anomalous magnetic moment. The proton radius puzzle (contribution to the Lamb shift) determines the strength of the interaction that contributes to the muon anomalous magnetic moment. The new contribution is just large enough to account for the current disagreement between theory and experiment. The equations in our paper allow us to obtain definite numbers, and these numbers can work out to be just right to account for both puzzles. New experiments will determine whether this is true physics or just a coincidence.”

    The physicists emphasize that they make no assumptions about the hypothetical particle other than that it could explain both of these puzzles. By constraining the mass of the hypothetical particle using data from previous experiments, the physicists predict that its mass would lie somewhere between 100 keV and 100 MeV.

    Although previous experiments have already explored part of this predicted range, the physicists have identified two unexplored regions that may be ideal places to look. They expect that future high-precision experiments involving protons and muons may be able to search for the particle in these regions.

    “We constrain the parameter space (mass and couplings) of this new particle in a finite range (except for the coupling of electrons),” Liu said. “So experimentalists can discover or exclude it by looking at a specific place, instead of measuring zero more and more accurately, like in the electron experiments.”

    In the meantime, the physicists are also looking forward to improved measurements of the muon anomalous magnetic moment—if the discrepancy remains, the results will offer further support for the existence of the new particle. The scientists also plan to apply some of the methods they developed here to look for other new particles.

    “Our work on this has allowed us to develop new theoretical tools to aid in the search for other kinds of bosons with different quantum numbers,” Miller said. “We will be applying those tools. Another direction is to develop a deeper theory that accommodates our new boson.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.

    So what defines us — the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 9:33 am on September 6, 2016 Permalink | Reply
    Tags: , , Circular Electron Positron Collider (CEPC) China, , , Particle Physics, Sixth Tone   

    From Sixth Tone: “Nobel Winner Says China Should Not Build Particle Collider” 

    Sixth Tone bloc

    Sixth Tone

    Sep 05, 2016
    Li You

    1
    A view of Compact Muon Solenoid (CMS) Cavern at the European Organization for Nuclear Research (CERN), Meyrin, Switzerland, Feb. 10, 2015. Richard Juilliart/AFP/VCG)

    Renowned physicist argues that building the world’s largest accelerator would not be worth the money.

    China’s ambitious plans to build its own particle collider will not be worth it, Nobel prize-winning physicist Chen-Ning Yang argued in a commentary published Sunday.

    2
    Circular Electron Positron Collider, possible map.http://america.pink/circular-electron-positron-collider_1000720.html

    Construction on the Circular Electron Positron Collider (CEPC) is slated to start in 2021. Upon its completion in six years, it would be the world’s largest particle accelerator. With a circumference of at least 50 kilometers — its exact size has not yet been decided — it would be far larger than the current record-holding machine, the Large Hadron Collider (LHC) at the European Organization for Nuclear Research, better known as CERN, beneath the border shared by France and Switzerland.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Such massive colliders allow scientists to study the universe’s smallest particles. The LHC in 2012 proved the existence of the Higgs boson, an elusive particle that had long puzzled scientists.

    CERN CMS Higgs Event
    CERN CMS Higgs Event

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    An even larger accelerator, such as the one planned by China, could collide particles at even higher energies and make discoveries that are impossible with existing colliders. However, some people in the scientific community, including Yang, do not agree with the project.

    In an article published on WeChat public account The Intellectual, the Chinese-born American physicist argues that the costs of building the super collider are too high and not worth it considering China’s current situation. Yang called the high cost of the collider “a bottomless pit,” comparing it to the Superconducting Super Collider project, which cost the U.S. $3 billion before being scrapped.

    Yang, who won a Nobel prize in 1957, believes the money should be used to address social problems, and argues funding the collider will result in lower budgets for other valuable scientific research.

    Chances of making any big discoveries are relatively low, Yang said. The CEPC would be used to search for so-called supersymmetry particles, which he says come from “a theory without experimental basis.” Moreover, Yang foresees the collider being run mostly by foreigners and being of little benefit to Chinese scientists. “Among the prominent high-energy physicists in the world, Chinese make up less than 1 or 2 percent,” he wrote.

    Wang Yifang, head of the government-run Institute of High Energy Physics (IHEP), the entity behind the collider project, replied on Monday with an article of his own, also published on The Intellectual.

    Wang denied that the cost of building CEPC would be endless, adding that international investment would cover 30 percent of the total expenses. He also said that 70 percent of the work would be done by Chinese scientists. Wang believes that building a large collider will attract overseas talent, cultivate young scientists at home, and be a leap for China in high-energy science.

    Also in response to Yang’s commentary, Sixth Tone’s sister publication The Paper on Monday published an article based on an interview with Rudiger Voss, head of international relations at CERN in Switzerland.

    Voss said that although the Chinese project would allow physicists to study the properties of the Higgs boson with greater precision and accuracy, the experiments would be limited in scope: The energy ranges of such experiments would be confined by the length of the tunnel, which in the case of China’s plans would be circular, and thus fixed.

    Plans are currently underway for a new linear collider that would be the result of an international collaborative effort, and would build on the current experiments being carried out at CERN’s LHC. The International Linear Collider project would be extendable in length, allowing for proportional increases in energy levels.

    According to media reports, the idea to build a Chinese super collider was first raised in 2012. Financial news outlet Caixin wrote in May that the government had yet to give any official comment.

    See the full article here .

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    There are five tones in Mandarin Chinese. When it comes to coverage of China, Sixth Tone believes there is room for other voices that go beyond buzzwords and headlines to tell the uncommon stories of common people.

    Through fresh takes on trending topics, in-depth features, and illuminating contributions, Sixth Tone covers issues from the perspectives of those most intimately involved to highlight the nuances and complexities of today’s China.

    We are a team of writers, editors, and researchers from within China and abroad. We belong to the state-funded Shanghai United Media Group, and share our offices with our sister publication, The Paper.

     
  • richardmitnick 8:44 am on September 5, 2016 Permalink | Reply
    Tags: 6 dimensional spacetime, , , , , Particle Physics,   

    From particlebites: “Gravity in the Next Dimension: Micro Black Holes at ATLAS” 

    particlebites bloc

    particlebites

    August 31, 2016
    Savannah Thais

    Article: Search for TeV-scale gravity signatures in high-mass final states with leptons and jets with the ATLAS detector at sqrt(s)=13 TeV
    Authors: The ATLAS Collaboration
    Reference: arXiv:1606.02265 [hep-ex]

    CERN/ATLAS detector
    CERN/ATLAS detector

    What would gravity look like if we lived in a 6-dimensional space-time? Models of TeV-scale gravity theorize that the fundamental scale of gravity, MD, is much lower than what’s measured here in our normal, 4-dimensional space-time. If true, this could explain the large difference between the scale of electroweak interactions (order of 100 GeV) and gravity (order of 1016 GeV), an important open question in particle physics. There are several theoretical models to describe these extra dimensions, and they all predict interesting new signatures in the form of non-perturbative gravitational states. One of the coolest examples of such a state is microscopic black holes. Conveniently, this particular signature could be produced and measured at the LHC!

    Sounds cool, but how do you actually look for microscopic black holes with a proton-proton collider? Because we don’t have a full theory of quantum gravity (yet), ATLAS researchers made predictions for the production cross-sections of these black holes using semi-classical approximations that are valid when the black hole mass is above MD. This production cross-section is also expected to dramatically larger when the energy scale of the interactions (pp collisions) surpasses MD. We can’t directly detect black holes with ATLAS, but many of the decay channels of these black holes include leptons in the final state, which IS something that can be measured at ATLAS! This particular ATLAS search looked for final states with at least 3 high transverse momentum (pt) jets, at least one of which must be a leptonic (electron or muon) jet (the others can be hadronic or leptonic). The sum of the transverse momenta, is used as a discriminating variable since the signal is expected to appear only at high pt.

    This search used the full 3.2 fb-1 of 13 TeV data collected by ATLAS in 2015 to search for this signal above relevant Standard Model backgrounds (Z+jets, W+jets, and ttbar, all of which produce similar jet final states). The results are shown in Figure 1 (electron and muon channels are presented separately). The various backgrounds are shown in various colored histograms, the data in black points, and two microscopic black hole models in green and blue lines. There is a slight excess in the 3 TeV region in the electron channel, which corresponds to a p-value of only 1% when tested against the background only hypothesis. Unfortunately, this isn’t enough evidence to indicate new physics yet, but it’s an exciting result nonetheless! This analysis was also used to improve exclusion limits on individual extra-dimensional gravity models, as shown in Figure 2. All limits were much stronger than those set in Run 1.

    1
    Figure 1: momentum distributions in the electron (a) and muon (b) channels

    2
    Figure 2: Exclusion limits in the Mth, MD plane for models with various numbers of extra dimensions

    So: no evidence of microscopic black holes or extra-dimensional gravity at the LHC yet, but there is a promising excess and Run 2 has only just begun. Since publication, ATLAS has collected another 10 fb-1 of sqrt(13) TeV data that has yet to be analyzed. These results could also be used to constrain other Beyond the Standard Model searches at the TeV scale that have similar high pt leptonic jet final states, which would give us more information about what can and can’t exist outside of the Standard Model. There is certainly more to be learned from this search!

    See the full article here .

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    What is ParticleBites?

    ParticleBites is an online particle physics journal club written by graduate students and postdocs. Each post presents an interesting paper in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

    The papers are accessible on the arXiv preprint server. Most of our posts are based on papers from hep-ph (high energy phenomenology) and hep-ex (high energy experiment).

    Why read ParticleBites?

    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. With each brief ParticleBite, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in particle physics.

    Who writes ParticleBites?

    ParticleBites is written and edited by graduate students and postdocs working in high energy physics. Feel free to contact us if you’re interested in applying to write for ParticleBites.

    ParticleBites was founded in 2013 by Flip Tanedo following the Communicating Science (ComSciCon) 2013 workshop.

    2
    Flip Tanedo UCI Chancellor’s ADVANCE postdoctoral scholar in theoretical physics. As of July 2016, I will be an assistant professor of physics at the University of California, Riverside

    It is now organized and directed by Flip and Julia Gonski, with ongoing guidance from Nathan Sanders.

     
  • richardmitnick 2:34 pm on August 24, 2016 Permalink | Reply
    Tags: , , , , Particle Physics   

    From CERN: “LHC pushes limits of performance’ 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    19 Aug 2016
    Harriet Kim Jarlett

    1

    The Large Hadron Collider’s (LHC) performance continued to surpass expectations, when this week it achieved 2220 proton bunches in each of its counter-rotating beams – the most it will achieve this year.

    This is not the maximum the machine is capable of holding (at full intensity the beam will have nearly 2800 bunches) but it is currently limited by a technical issue in the Super Proton Synchrotron (SPS).

    CERN  Super Proton Synchrotron
    “CERN Super Proton Synchrotron

    “Performance is excellent, given this limitation,” says Mike Lamont, head of the Operations team. “We’re 10% above design luminosity (which we surpassed in June), we have these really long fills (where the beam is circulating for up to 20 hours or so) and very good collision rates. 2220 bunches is just us squeezing as much in as we can, given the restrictions, to maximize delivery to the experiments.”

    As an example of the machine’s brilliant performance, with almost two months left in this year’s run it has already reached an integrated luminosity of 22fb-1 – very close to the goal for 2016 of 25fb-1 (up from 4fb-1 last year.)

    Luminosity is an essential indicator of the performance of an accelerator, measuring the potential number of collisions that can occur in a given amount of time, and integrated luminosity (measured in inverse femtobarns, fb-1) is the accumulated number of potential collisions. At its peak, the LHC’s proton-proton collision rate reaches about 1 billion collisions per second giving a chance that even the rarest processes at the highest energy could occur.

    The SPS is currently experiencing a small fault that could be exacerbated by high beam intensity – hence the number of proton bunches sent to the LHC per injection is limited to 96, compared to the normal 288.

    “Once this issue is fixed in the coming year-end technical stop, we’ll be able to push up the number of bunches even further. Next year we should be able to go to new record levels,” says Lamont with a wry grin.

    See the full article here.

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    Meet CERN in a variety of places:

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 2:13 pm on August 24, 2016 Permalink | Reply
    Tags: , , , , , Particle Physics   

    From Nature- “China, Japan, CERN: Who will host the next LHC?” 

    Nature Mag
    Nature

    [The title is in error. There will possibly be another particle accelerator, or more than one. But none will be the LHC. It is what it is. They will want and need a new name. Might I suggest superconducting super collider, and might I suggest the United States?]

    19 August 2016
    Elizabeth Gibney

    Labs are vying to build ever-bigger colliders against a backdrop of uncertainty about how particle physicists will make the next big discoveries.

    1
    Whether the Large Hadron Collider will find phenomena outside the standard model of particle physics remains to be seen. Harold Cunningham/Getty

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    It was a triumph for particle physics — and many were keen for a piece of the action. The discovery of the Higgs boson in 2012 using the world’s largest particle accelerator, the Large Hadron Collider (LHC), prompted a pitch from Japanese scientists to host its successor. The machine would build on the LHC’s success by measuring the properties of the Higgs boson and other known, or soon-to-be-discovered, particles in exquisite detail.

    But the next steps for particle physics now seem less certain, as discussions at the International Conference on High Energy Physics (ICHEP) in Chicago on 8 August suggest. Much hinges on whether the LHC unearths phenomena that fall outside the standard model of particle physics — something that it has not yet done but on which physicists are still counting — and whether China’s plans to build an LHC successor move forward.

    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 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.

    When Japanese scientists proposed hosting the International Linear Collider (ILC), a group of international scientists had already drafted its design. The ILC would collide electrons and positrons along a 31-kilometre-long track, in contrast to the 27-kilometre-long LHC, which collides protons in a circular track that is based at Europe’s particle-physics laboratory, CERN (See ‘World of colliders’).

    ILC schematic
    ILC schematic

    Because protons are composite particles made of quarks, collisions create a mess of debris. The ILC’s particles, by contrast, are fundamental and so provide the cleaner collisions more suited to precision measurements, which could reveal deviations from expected behaviour that point to physics beyond the standard model.

    Higgs study

    For physicists, the opportunity to carry out detailed study of the Higgs boson and the heaviest, ‘top’ quark, the second most recently discovered particle, is reason enough to build the facility. Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT) was expected to make a call on whether to host the project — which could begin experiments around 2030 — in 2016. But the Japanese panel advising MEXT indicated last year that opportunities to study the Higgs boson and the top quark would not on their own justify building the ILC, and that it would wait until the end of the LHC’s first maximum-energy run – scheduled for 2018 – before making a decision.

    That means the panel is not yet convinced by the argument that the ILC should be built irrespective of what the LHC finds, says Masanori Yamauchi, director-general of Japan’s High Energy Accelerator Research Organization (KEK) in Tsukuba who sat on an ICHEP panel at a session on future facilities. “That’s the statement hidden under their statement,” he says.

    If the LHC discovers new phenomena, these would be further fodder for ILC study — and would strengthen the case for building the high precision machine.

    US physicists have long backed building a linear collider. And a joint MEXT and US Department of Energy group is discussing ways to reduce the ILC’s costs, says Yamauchi, which are now estimated at US$10 billion. A reduction of around 15% is feasible — but Japan will need funding commitments from other countries before it formally agrees to host, he added.

    Chinese competitor

    Snapping at Japan’s heels is a Chinese team. In the months after the Higgs discovery, a team of physicists led by Wang Yifang, director of the Institute of High Energy Physics in Beijing, floated a plan to host a collider in the 2030s, also partially funded by the international community and focused on precision measurements of the Higgs and other particles.

    2
    Circular rather than linear, this 50–100-kilometre-long electron–positron smasher would not reach the energies of the ILC. But it would require the creation of a tunnel that could allow a proton–proton collider — similar to the LHC, but much bigger — to be built at a hugely reduced cost.

    Wang and his team this year secured around 35 million yuan (US$5 million) in funding from China’s Ministry of Science and Technology to continue research and development for the project, Wang told the ICHEP session. Last month, China’s National Development and Reform Commission turned down a further request from the team for 800 million yuan, but other funding routes remain open, Wang said, and the team now plans to focus on raising international interest in the project.

    By affirming worldwide interest in Higgs physics, the Chinese proposal bolsters Japan’s case for building the ILC, says Yamauchi. But if it goes ahead, it could drain international funding from the ILC and put its future on shakier ground. “It may have a negative impact,” he says.

    Super-LHC

    In the future, the option to use China’s electron–positron collider as the basis for a giant proton–proton collider could interfere with CERN’s own plans for a 100-kilometre-circumference circular machine that would smash protons together at more than 7 times the energy of the LHC. Until the mid-2030s, CERN will be busy with an upgrade that will raise the intensity — but not the energy — of the LHC’s proton beam. And by that time, China might have a suitable tunnel that could make it harder to get backing for this ‘super-LHC’.

    At ICHEP, Fabiola Gianotti, CERN’s director-general, floated an interim idea: souping up the energy of the LHC beyond its current design by installing a new generation of superconducting magnets by around 2035. This would provide a relatively modest boost in energy — from 14 teraelectronvolts (TeV) to 20 TeV — that would have a strong science case if the LHC finds new physics at 14 TeV, said Gianotti. Its $5-billion price tag could be paid for out of CERN’s regular budget.

    For decades, successive facilities have found particles predicted by the standard model, and neither the LHC nor any of its proposed successors is guaranteed to find new physics. Questions asked at the ICHEP session revealed some soul-searching among attendees, including a plea to reassure young high-energy physicists about the future of the field and contemplation of whether money would be better spent on other approaches rather than ever-bigger accelerators.

    Indeed, the US is betting on neutrinos, fundamental particles that could reveal physics beyond the standard model, not colliders. The Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, hopes to become the world capital of neutrino physics by hosting the $1-billion Long-Baseline Neutrino Facility, which will beam neutrinos to a range of detectors starting in 2026.

    FNAL LBNFFNAL DUNE Argon tank at SURF
    SURF logo
    Sanford Underground levels
    LBMF/DUNE map from FNAL, Batavia, IL to SURF, SD, USA; DUNE’s Argon tank; SURF caverns for science

    Funding will require approval from US Congress in 2017. But at the ICHEP session, Fermilab director Nigel Lockyer was confident: “We are beyond the point of no return. It is happening.”

    See the full article here .

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    Stem Education Coalition

    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 9:55 am on August 23, 2016 Permalink | Reply
    Tags: , , , NuMI horn, Particle Physics,   

    From FNAL: “Funneling fundamental particles” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    August 22, 2016
    Molly Olmstead

    1
    The NuMI horn in the Main Injector brings particles into focus. Photo: Reidar Hahn

    Neutrinos are tricky. Although trillions of these harmless, neutral particles pass through us every second, they interact so rarely with matter that, to study them, scientists send a beam of neutrinos to giant detectors. And to be sure they have enough of them, scientists have to start with a very concentrated beam of neutrinos.

    To concentrate the beam, an experiment needs a special device called a neutrino horn.

    An experiment’s neutrino beam is born from a shower of short-lived particles, created when protons traveling close to the speed of light slam into a target. But that shower doesn’t form a tidy beam itself: That’s where the neutrino horn comes in.

    Once the accelerated protons smash into the target to create pions and kaons — the short-lived charged particles that decay into neutrinos — the horn has to catch and focus them by using a magnetic field. The pions and kaons have to be focused immediately, before they decay into neutrinos: Unlike the pions and kaons, neutrinos don’t interact with magnetic fields, which means we can’t focus them directly.

    Without the horn, an experiment would lose 95 percent of the neutrinos in its beam. Scientists need to maximize the number of neutrinos in the beam because neutrinos interact so rarely with matter. The more you have, the more opportunities you have to study them.

    “You have to have tremendous numbers of neutrinos,” said Jim Hylen, a beam physicist at Fermilab. “You’re always fighting for more and more.”

    Also known as magnetic horns, neutrino horns were invented at CERN by the Nobel Prize-winning physicist Simon van der Meer in 1961. A few different labs used neutrino horns over the following years, and Fermilab and J-PARC in Japan are the only major laboratories now hosting experiments with neutrino horns. Fermilab is one of the few places in the world that makes neutrino horns.

    “Of the major labs, we currently have the most expertise in horn construction here at Fermilab,” Hylen said.

    How they work

    The proton beam first strikes the target that sits inside or just upstream of the horn. The powerful proton beam would punch through the aluminum horn if it hit it, but the target, which is made of graphite or beryllium segments, is built to withstand the beam’s full power. When the target is struck by the beam, its temperature jumps by more than 700 degrees Fahrenheit, making the process of keeping the target-horn system cool a challenge involving a water-cooling system and a wind stream.

    Once the beam hits the target, the neutrino horn directs resulting particles that come out at wide angles back toward the detector. To do this, it uses magnetic fields, which are created by pulsing a powerful electrical current — about 200,000 amps — along the horn’s surfaces.

    “It’s essentially a big magnet that acts as a lens for the particles,” said physicist Bob Zwaska.

    The horns come in slightly different shapes, but they generally look on the outside like a metal cylinder sprouting a complicated network of pipes and other supporting equipment. On the inside, an inner conductor leaves a hollow tunnel for the beam to travel through.

    Because the current flows in one direction on the inner conductor and the opposite direction on the outer conductor, a magnetic field forms between them. A particle traveling along the center of the beamline will zip through that tunnel, escaping the magnetic field between the conductors and staying true to its course. Any errant particles that angle off into the field between the conductors are kicked back in toward the center.

    The horn’s current flows in a way that funnels positively charged particles that decay into neutrinos toward the beam and deflects negatively charged particles that decay into antineutrinos outward. Reversing the current can swap the selection, creating an antimatter beam. Experiments can run either beam and compare the data from the two runs. By studying neutrinos and antineutrinos, scientists try to determine whether neutrinos are responsible for the matter-antimatter asymmetry in the universe. Similarly, experiments can control what range of neutrino energies they target most by tuning the strength of the field or the shape or location of the horn.

    Making and running a neutrino horn can be tricky. A horn has to be engineered carefully to keep the current flowing evenly. And the inner conductor has to be as slim as possible to avoid blocking particles. But despite its delicacy, a horn has to handle extreme heat and pressure from the current that threaten to tear it apart.

    “It’s like hitting it with a hammer 10 million times a year,” Hylen said.

    Because of the various pressures acting on the horn, its design requires extreme attention to detail, down to the specific shape of the washers used. And as Fermilab is entering a precision era of neutrino experiments running at higher beam powers, the need for the horn engineering to be exact has only grown.

    “They are structural and electrical at the same time,” Zwaska said. “We go through a huge amount of effort to ensure they are made extremely precisely.”

    See the full article here .

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    FNAL Icon
    Fermilab Campus

    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.

     
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