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  • richardmitnick 10:17 pm on January 14, 2021 Permalink | Reply
    Tags: "HL-LHC magnets enter production in the US", , , , , , FNAL, , , , , , US LHC Accelerator Research Program (LARP)   

    From CERN (CH) Courier: “HL-LHC magnets enter production in the US” 


    From CERN (CH) Courier

    13 January 2021
    Matthew Chalmers editor.


    1
    Next generation BNL technicians Ray Ceruti, Frank Teich, Pete Galioto, Pat Doutney and Dan Sullivan with the second US quadrupole magnet for the HL-LHC to have reached design performance. Credit: BNL.

    The significant increase in luminosity targeted by the high-luminosity LHC (HL-LHC) demands large-aperture quadrupole magnets that are able to focus the proton beams more tightly as they collide. A total of 24 such magnets are to be installed on either side of the ATLAS and CMS experiments [both below] in time for HL-LHC operations in 2027, marking the first time niobium-tin (Nb3Sn) magnet technology is used in an accelerator.

    Nb3Sn is a superconducting material with a critical magnetic field that far exceeds that of the niobium-titanium presently used in the LHC magnets, but once formed it becomes brittle and strain-sensitive, which makes it much more challenging to process and use.

    The milestone signals the end of the prototyping phase for the HL-LHC quadrupoles.

    Following the first successful test of a US-built HL-LHC quadrupole magnet at Brookhaven National Laboratory (BNL) in January last year—attaining a conductor peak field of 11.4 T and exceeding the required integrated gradient of 556 T in a 150 mm-aperture bore—a second quadrupole magnet has now been tested at BNL at nominal performance. Since the US-built quadrupole magnets must be connected in pairs before they can constitute fully operational accelerator magnets, the milestone signals the end of the prototyping phase for the HL-LHC quadrupoles, explains Giorgio Apollinari of Fermilab, who is head of the US Accelerator Upgrade Projects (AUP). “The primary importance is that we have entered the ‘production’ period that will make installation viable in early 2025. It also means we have satisfied the requirements from our funding agency and now the US Department of Energy has authorised the full construction for the US contribution to HL-LHC.”

    Joint venture

    The design and production of the HL-LHC quadrupole magnets are the result of a joint venture between CERN, BNL, Fermilab and Lawrence Berkeley National Laboratory, preceded by the 15 year-long US LHC Accelerator Research Program (LARP).

    The US labs are to provide a total of ten 9 m-long helium-tight vessels (eight for installation and two as spares) for the HL-LHC, each containing two 4.2 m-long magnets. CERN is also producing ten 9 m-long vessels, each containing a 7.5 m-long magnet. The six magnets to be placed on each side of ATLAS and CMS – four from the US and two from CERN – will be powered in series on the same electrical circuit.

    The synergy between CERN and the US laboratories allowed us to considerably reduce the risks.

    “The synergy between CERN and the US laboratories allowed us to considerably reduce the risks, have a faster schedule and a better optimisation of resources,” says Ezio Todesco of CERN’s superconductors and cryostats group. The quadrupole magnet programme at CERN is also making significant progress, he adds, with a short-model quadrupole having recently reached a record 13.4 T peak field in the coil, which is 2 T more than the project requirements. “The full series of magnets, sharing the same design and built on three sites, will also give very relevant information about the viability of future hadron colliders, which are expected to rely on massive, industrial production of Nb3Sn magnets with fields up to 16 T.”

    Since the second US quadrupole magnet was tested in October, the AUP teams have completed the assembly of a third magnet and are close to completing the assembly of a fourth. Next, the first two magnets will be assembled in a single cold mass before being tested in a horizontal configuration and then shipped to CERN in time for the “string test” planned in 2023.

    “In all activities at the forefront of technology, like in the case for these focusing Nb3Sn quadrupoles, the major challenge is probably the transition from an ‘R&D mentality’, where minor improvements can be a daily business, to a ‘production mentality’, where there is a need to build to specific procedures and criteria, with all deviations being formally treated and corrected or addressed,” says Apollinari. “And let’s not forget that the success of this second magnet test came with a pandemic raging across the world.”

    See the full article here .


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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    CERN/ATLAS detector

    ALICE

    CERN/ALICE Detector


    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN map

    SixTRack CERN LHC particles

     
  • richardmitnick 9:45 am on December 1, 2020 Permalink | Reply
    Tags: , FNAL, FNAL IOTA project,   

    From DOE’s Fermi National Accelerator Laboratory: “Undulator magnet for the optical stochastic cooling experiment in IOTA” Photo Study 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

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

    FNAL IOTA project.

    After the first electron beam was circulated in August 2018, the experimental program at the Fermilab Integrable Optics Test Accelerator (IOTA) continues with commissioning of machine and diagnostics and with the first beam-physics experiments.

    Photo Study

    2
    The optical stochastic cooling experiment’s undulator magnet installed in the Fermilab Integrable Optics Test Accelerator, or IOTA, in November. Credit: Giulio Stancari.

    3
    This detail shows the the gap between the OSC undulator magnet coils and poles. Credit: Giulio Stancari.

    4
    Traveling through the magnet, the electron beam generates infrared light, which is used to detect its position and velocity. The OSC experiment will use for the first time this light to increase the density of the electron beam and therefore improve the performance of future high-energy physics experiments. Credit: Giulio Stancari.

    See the full here.


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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.

     
  • richardmitnick 2:03 pm on October 2, 2020 Permalink | Reply
    Tags: FNAL, Northern Illinois flourishes as accelerator R&D hub under Fermilab leadership   

    From FNAL: Northern Illinois flourishes as accelerator R&D hub under Fermilab leadership 

    September 25, 2020

    Steve Koppes

    Only a handful of particle accelerators around the world can produce proton beams intense enough for use in neutrino experiments. Europe and Japan each has an accelerator chain. So does the U.S. Department of Energy’s Fermi National Accelerator Laboratory.

    Fermilab, however, is the only laboratory that produces protons at energies suitable for both low- and high-energy neutrino experiments. In fact, it produces the most intense neutrino beam in the world. This is but one example of Fermilab’s accelerator prowess. The laboratory’s collaborations with nearby universities and research laboratories have established the northern Illinois region as a leader in multiple areas of particle accelerator science and technology.

    “In Chicago we have a very strong academic environment, not only in physics, in fundamental science, but also in applied science as well as engineering,” said Sergei Nagaitsev, head of Fermilab’s accelerator science programs and a University of Chicago faculty member.

    This has led to accelerator research collaborations with the Illinois Institute of Technology, Northern Illinois University, Northwestern University and the University of Chicago.

    “The combined accelerator R&D portfolio of Fermilab and collaborating Illinois institutions covers nearly every facet of particle acceleration, from basic principles to applications of accelerators in industry,” said Fermilab Chief Technology Officer Sergey Belomestnykh.

    A spectrum of discovery and invention

    Together with its northern Illinois partners, Fermilab grapples with multiple scientific and engineering challenges that are vitally important to improving accelerator beams and experimental outcomes.

    “It’s hard to point at where science ends and technology begins,” Nagaitsev said. “There is a spectrum of discovery on one side versus invention on the other side. Both require creativity from our scientists and engineers.”

    Researchers at Fermilab, Illinois Institute of Technology, Northern Illinois University and the University of Chicago all use IOTA, the Integrable Optics Test Accelerator, a major component of the lab’s accelerator-science enterprise and one of only a few accelerators in the world dedicated to studying the physics of beams. Photo: Giulio Stancari, Fermilab.

    The physics of beams

    The challenges on the accelerator science side relate to the physics of the beam itself.

    Scientists work to produce beams of higher quality, which is connected to properties such as beam size and spread; achieve better measurements and control of beams down to the level of individual particles; predict beam behavior with better fidelity using computer simulations; and produce beams of higher intensity.

    “Our particle physics experiments, especially the neutrino experiments, are hungry for intense proton beams delivered to the target,” Nagaitsev said.

    To investigate problems in beam physics, Fermilab operates the Integrable Optics Test Accelerator, called IOTA, a major component of the lab’s accelerator-science enterprise and one of only a few accelerators in the world dedicated to studying the physics of beams. Researchers at Fermilab, IIT, NIU and the University of Chicago all use IOTA. Their work includes studies of electron and proton beams in rings, and their results will directly affect the Fermilab high-intensity proton rings used for neutrino and other particle physics research. Nagaitsev and his colleagues will also soon aim to demonstrate a new beam cooling technique called optical stochastic cooling — a novel way to improve the beam’s quality.

    Science and technology of superconductivity

    Science and technology of superconductivity is critical for building modern particle accelerators. Superconducting radio-frequency cavities – structures that impart energy to a particle beam – provide high levels of acceleration, making it more efficient, while high-field superconducting magnets allow tighter bending of particle trajectories, thus reducing the footprint of future accelerators. Members of Fermilab’s Applied Physics and Superconducting Technology Division are at the forefront of this field.

    “It’s a cool blend of basic and applied science. We’re applying our understanding of the principles of materials science to giant particle-accelerating machines,” Belomestnykh said. “In turn, these machines enable us to scrutinize matter’s fundamental constituents.”

    In July, Fermilab set the new world record for field strength for a superconducting accelerator dipole magnet – 14.5 teslas. And it is ambitiously setting its sights on developing magnets that can generate a field of 20 teslas — about 2,000 times higher than a strong refrigerator magnet.

    Among achievements in superconducting radio-frequency technology, Fermilab researchers have discovered ways to significantly boost the cavity’s efficiency and accelerating field, both of which are crucial for future particle accelerators. And it turns out that these cavities, developed for accelerators, find applications in somewhat unexpected areas. They are leading candidates for scalable quantum computing technology thanks to the exceptionally long times they can maintain energy. The same technology has proven to be very useful in a search for elusive dark matter particles, such as dark photons.

    Here, too, Fermilab collaborates with regional partners. For example, scientists at the Center for Applied Physics and Superconducting Technologies, known as CAPST, a collaboration between Fermilab and nearby Northwestern University, are exploring the upper limits of superconductivity to design and build more powerful and efficient accelerator components.

    “The importance of superconductivity research for particle accelerators can not be overstated,” said Fermilab Deputy Chief Technology Officer and CAPST Co-Director Anna Grassellino. “We’re making great strides in this area in northern Illinois.”

    Scientists at Fermilab are studying superconductivity to design and build more powerful and efficient accelerator components. Several Fermilab and Northwestern University scientists are part of Center for Applied Physics and Superconducting Technologies to explore the upper limits of superconductivity. Photo: Reidar Hahn, Fermilab.

    Targets and beams

    There’s also the science and technology of targetry: engineering materials to withstand the powerful particle beams smashing into them.

    “Suppose we resolve the challenge of making beams very intense. Then you put them on a target and the target melts,” Nagaitsev said. “There has to be continuing research on how to make the targets more robust so that when the science delivers high-intensity beams, the target can take it.”

    Toward autonomous accelerators

    Fermilab scientists are exploring the use of artificial intelligence and machine learning for tuning accelerators, delivering flexible beam patterns and increasing a machine’s uptime. This steady move toward autonomous accelerator operation means that, one day, accelerators could run with little to no human intervention. Researchers are carrying out autonomous-accelerator studies at the Fermilab Science and Technology facility and at Fermilab’s PIP-II Injector Test Facility, a proving ground for the future heart of the lab’s accelerator complex, its PIP-II accelerator.

    A number of these studies are being conducted as part of a program led by the University of Chicago.

    And in the next five years or so, Fermilab’s accelerator researchers would like to build an electron injector for testing a potential way to do large-scale quantum computing.

    “Fermilab has many interesting research plans for both near and far future,” Nagaitsev promised.

    Accelerator applications

    The use of accelerator technology goes beyond the academic. The world’s more than 30,000 operating particle accelerators also shrink tumors, make better tires, spot suspicious cargo, clean up dirty drinking water and help design drugs.

    To facilitate the application of accelerators for societal benefit, Fermilab established the IARC at Fermilab (formerly known as the Illinois Accelerator Research Center), a technology development hub that connects scientists with members of industry. Industry partners are welcome to use the lab’s facilities to try out accelerator-related concepts. For example, IARC’s Accelerator Applications Development and Demonstration Facility, known as A2D2, is a test platform experts can use to evaluate new ideas for electron-beam applications.

    “We have a wonderful concentration of accelerator expertise at Fermilab and in northern Illinois, and we’re facilitating cross-pollination with people who are innovating accelerator-based technologies for our everyday lives,” said Tim Meyer, head of Fermilab Technology Engagements. “By putting our heads together, by sharing our capabilities and facilities, we’re discovering uses for particle accelerators we wouldn’t otherwise.”

    One of IARC’s goals is to make the technologies developed for science more widely available for commercial applications. For example, experts at IARC are developing a compact, mobile, superconducting particle accelerator that would fit on a truck for a variety of applications. To help realize that goal, they’ve also developed a new cooling method to reduce the bulk of the traditional infrastructure needed to cool it to cryogenic temperatures.

    IARC at Fermilab is a technology development hub that connects scientists with members of industry. Photo: Reidar Hahn, Fermilab.

    Accelerating the workforce

    The potential of accelerators is boundless, so accelerator research is a strong draw for early-career scientists. Perhaps this explains why Mike Syphers, an NIU research professor of physics, has yet to see a saturated demand for accelerator scientists, even as large projects have come and gone.

    The U.S. Particle Accelerator School, he noted, attracts near-record-setting numbers of students every year. Fermilab hosts and manages this national, graduate-level program, which provides training and workforce development in the science and technology of charged-particle accelerators and associated systems.

    Multiple training programs will help develop young scientists to help realize the field’s future plans.

    The Joint University-Fermilab Doctoral Program in Accelerator Physics and Technology, for example, has graduated 53 Ph.D. students since its establishment in 1985. Three more are currently in the pipeline.

    Students study at the U.S. Particle Accelerator School hosted by Northern Illinois University in 2017. USPAS is just one particle accelerator science program in which Fermilab participates. Others include The Joint University-Fermilab Doctoral Program in Accelerator Physics and Technology and the Chicagoland Accelerator Science Traineeship, launched by NIU and IIT. Photo: USPAS.

    A related effort, launched by NIU and IIT and funded with $1.9 million from the U.S. Department of Energy, is the Chicagoland Accelerator Science Traineeship. The traineeships will provide up to two years of funding for graduate students at NIU and IIT to prepare them for careers in accelerator science and technology. Fermilab also participates in two other similar programs: the Accelerator Science and Engineering Traineeship at Michigan State University and the Ernest Courant Traineeship in Accelerator Science & Engineering at Stony Brook University.

    Two Fermilab internships attract students interested in particle accelerator physics and technology to the lab: The Lee Teng Internship is a joint program between Fermilab and neighboring Argonne National Laboratory for undergraduate students. The Helen Edwards Summer Internship brings European physics and engineering students to Fermilab.

    “The field has continued to grow as the use of particle accelerators has expanded beyond national laboratories and pure scientific research,” Syphers said. “Various applications of accelerators and medical uses have driven further demand for people with knowledge of these devices.”

    Building acceleration

    Fermilab stands alone as a laboratory that can deliver the most intense beam of neutrinos in the world and accelerate beams for low- and high-energy neutrino experiments. This is thanks to a major accelerator upgrade currently under way at the lab: the Proton Improvement Plan-II. The heart of PIP-II will be the construction of a 215-meter-long superconducting accelerator that can generate powerful proton beams for the lab’s experiments.

    Again, partnership is key: Argonne National Laboratory — a 30-mile jaunt from Fermilab — pursues accelerator R&D and serves as one of Fermilab’s U.S. partners in PIP-II. And Fermilab collaborates with Argonne accelerator research groups at the Advanced Photon Source, the Argonne Tandem Linac Accelerator System and the Argonne Wakefield Accelerator Facility.

    With PIP-II scheduled to become fully operational in the late 2020s, NIU’s Syphers is already helping to develop plans for Fermilab’s next accelerator upgrade path.

    “We have to start thinking now about what the next step would be beyond PIP-II because it would take years to plan,” Syphers said.

    Fermilab and partners, including Argonne National Laboratory and Northern Illinois University, are designing and building the upcoming PIP-II accelerator, scheduled to become fully operational in the late 2020s. Photo: Reidar Hahn, Fermilab.

    While prototyping and testing of PIP-II components take place, researchers already are discussing ideas for improvements beyond the new machine, for example, doubling the number of protons Fermilab’s accelerator chain would send to experiments.

    Intense proton beams are necessary to produce the neutrinos for the international Deep Underground Neutrino Experiment, or DUNE, hosted by Fermilab, and its Long-Baseline Neutrino Facility. By studying neutrinos, the most abundant matter particles in the universe, DUNE discoveries could revolutionize cosmological research.

    PIP-II boasts collaborators beyond Illinois borders: It is the only accelerator project in the U.S. that receives major international contributions.

    Once operational, PIP-II will dramatically boost Fermilab’s proton production for DUNE and future research programs.

    “We are always innovating technologies to help design and build the leanest and most powerful machines we can for discovery,” Belomestnykh said. “In sharing those innovations with our global partners, we’re helping advance accelerator technology not just in Illinois, but around the world.”

    For example, together with other DOE national laboratories, Fermilab leads the U.S. effort to design, build and test next-generation focusing magnets for upgrading the Large Hadron Collider at CERN and is building superconducting cryomodules for the Linac Coherence Light Source-II project, a revolutionary X-ray laser under construction at SLAC National Accelerator Laboratory.

    “Accelerator science and technology is one Fermilab’s core competencies. Together with our regional partners, we are striving to make Chicagoland the next Silicon Valley for particle accelerators and their applications,” Nagaitsev said. “With the unparalleled wealth of accelerator knowledge and activity here in one of the tech hubs of the country, we’re very well positioned to do just that.”

    Fermilab accelerator R&D is supported by the DOE Office of Science.

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

    See the full article here:

     
  • richardmitnick 5:21 pm on July 18, 2020 Permalink | Reply
    Tags: A new proposed experiment called FerMINI., , FNAL, , , The search for millicharged particles in the MeV/c2 to few GeV/c2 mass range.   

    From Fermi National Accelerator Lab: “Searching for millicharged particles” 

    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.

    July 17, 2020
    Yu-Dai Tsai

    [I am in the hospital and copy/paste for images is not working (Thankyou RWJ Barnabas Robert Wood Johnson Hospital. See the full article for images. All images which show are a part of the .html template I have built for the institution.)

    Ever since Robert Millikan’s 1909 discovery of electric charge and, later, the discovery of the quark, scientists have postulated electric charge to come in discrete units, and the minimal electric charge has been believed to be carried by quarks. Yet theories still postulate that particles can carry much smaller charges — significantly smaller than that of quarks.

    Scientists, including Fermilab researchers, have proposed a new experiment to help search for these “millicharged particles.” The proposal is inspired by analyses based on results from several neutrino experiments. The potential discovery would shatter the current Standard Model paradigm and open a window to new physics.

    The new proposed experiment is called FerMINI [https://arxiv.org/abs/1812.03998] which has the ability to search for millicharged particles in the MeV/c2 to few GeV/c2 mass range.

    FerMINI builds on previous analyses [https://inspirehep.net/literature/1708533]. A group of theoretical physicists showed that data from neutrino experiments MiniBooNE at Fermilab, the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory, and Super-Kamiokande Observatory in Japan limits the possible range of mass and electric charge that millicharged particles can have. Their findings narrow the region where scientists should look for millicharged particles. Independent and detailed millicharge analyses were studied for the ArgoNeuT neutrino experiment and conducted by the ArgoNeuT collaboration.

    The search could extend beyond MiniBooNE and LSND to other Fermilab neutrino experiments, including MicroBooNE and the Short-Baseline Near Detector. Further, experiments such as the international, Fermilab-hosted Deep Underground Neutrino Experiment, or DUNE, and CERN’s proposed experiment, the Search for Hidden Particles, called SHiP, have the potential to discover millicharged particles in mass ranges that have yet to be experimentally tested. This research may have implications for their detector designs and analysis techniques.

    The FerMINI detector can sense millicharged particles produced in the Fermilab proton beam when it hits a fixed target. It detects multiple scintillation hits in a small time window as the millicharged-particle signature. The detector technology is inspired by the milliQan experiment, a proposed search at the Large Hadron Collider at CERN, some of whose collaborators are also involved in the FerMINI project.

    The search could potentially help explain the nature of dark matter, as the hypothetical particle could contribute to a fraction of the universe’s dark matter abundance. For example, scientists on the Experiment to Detect the Global EoR Signature, or EDGES, recently reported an anomaly in the 21-centimeter hydrogen absorption spectrum from the early universe. The discovery of millicharged particles as a fraction of dark matter might explain the anomaly.

    This type of fractional dark matter candidate, with sizable coupling to Standard Model particles, would be hard for underground direct-detection experiments to detect, because the dark matter particles would lose their kinetic energy through their interaction with Earth’s atmosphere and crust before they reach the underground detectors. The Fermilab experiments thus have advantages in detecting such particles since they can directly produce these particles from the proton beam with a high energy.

    We now know where we can look in searching for these millicharged particles, given available capabilities. By combining detector technology with existing and planned high-intensity proton beams provided by Fermilab, we can advance our search for these mysterious particles, overturning our understanding of the structure of nature’s fundamental constituents.

    The FerMINI collaboration, based at Fermilab, comprises 10 institutions.

    This work is supported by the DOE Office of Science.

    See the full here.


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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.

     
  • richardmitnick 1:04 pm on June 22, 2020 Permalink | Reply
    Tags: "CMS collaboration publishes 1000th paper", , , CMS became the first experiment in the history of HEP to reach this outstanding total of papers., FNAL, , , , ,   

    From Fermi National Accelerator Lab: “CMS collaboration publishes 1,000th paper” 

    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.

    June 22, 2020
    Boaz Klima

    We are proud to share with you the exciting news that on Friday, June 19, CMS reached a momentous milestone by submitting its 1,000th paper for publication [Physical Review Letters]. In doing so, CMS became the first experiment in the history of HEP to reach this outstanding total of papers.

    CERN/CMS Detector

    The very first paper published by the CMS collaboration as a whole was a description of the detector, submitted early in 2008. This was followed in 2009 by a series of papers describing the preoperation tuning of the apparatus using cosmic rays. The first publications of physics results based on LHC collisions appeared very soon after the LHC commenced operation at the end of 2009, and they have been issued at an average rate of about 100 papers per year since then. The publications timeline of collider-data papers split by physics topics is available on the CMS publications webpage.

    The scientific impact of CMS publications has been at the highest level. Approximately a third are published as letters in Physical Review Letters or Physics Letters B, where the standards for significance and timeliness are even more stringent than those required for longer articles. Indeed, several CMS letters have been singled out for special recognition as “Editor’s Selection,” a testament to the utmost importance of those results.

    By happy coincidence, the 1,000th CMS paper has been submitted close to the eighth anniversary of the most notable paper submitted so far, that reporting the observation of the Higgs boson, paper number 183, which was submitted in July 2012. The discovery of the Higgs boson led to a Nobel Prize.

    Not only has the number of papers produced by CMS reached an unprecedented level, but the diversity of physics topics covered is also unparalleled. Just one decade ago the high-energy physics field exploited three different types of accelerators to pursue separately research at the energy frontier, the intensity frontier and on heavy-ion collisions under extreme conditions. In contrast, the advanced design of the CMS detector, made possible by a long program of R&D, and the remarkable flexibility of the LHC accelerator, have enabled CMS to publish world-class results probing all three boundaries of knowledge.

    The exceptional success of CMS is a testimony to the skill and dedication of the collaboration, and credit for reaching the milestone of 1,000 publications belongs to all its members.

    See the full 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.

     
  • richardmitnick 12:42 pm on June 22, 2020 Permalink | Reply
    Tags: "Interview with Nobel laureate Carlo Rubbia about neutrino research" Video, , FNAL, ,   

    From Fermi National Accelerator Lab: “Interview with Nobel laureate Carlo Rubbia about neutrino research” Video 

    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.

    In this 5-minute video, Nobel laureate Carlo Rubbia explains why mysterious particles called neutrinos could be the key to understanding the nature of the universe. He talks about the search for a fourth type of neutrino and why the universe would not exist without neutrinos. He describes how scientists aim to unveil the secrets of the neutrino with the ICARUS (https://icarus.fnal.gov) and DUNE (https://fnal.gov/dune) neutrino experiments, hosted by Fermilab (https://fnal.gov). He recalls why early in his career he chose liquid argon as his material of choice to collect information about neutrino interactions with matter.

    FNAL/ICARUS

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

    See the full here.


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

     
  • richardmitnick 1:01 pm on June 20, 2020 Permalink | Reply
    Tags: "Silicon detector R&D for future high-energy physics experiments", , , FNAL, , , ,   

    From Fermi National Accelerator Lab: “Silicon detector R&D for future high-energy physics experiments” 

    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.

    June 19, 2020
    Ron Lipton

    Our ability to explore the physics of elementary particles depends on the sensors we use to translate flows of energy from particle collisions in our accelerators into electronic pulses in our detectors. The patterns of these pulses are used to reconstruct the underlying particles and their interactions. At the core of the mammoth detector assemblies and snugly surrounding the beam pipes are arrays of silicon sensors. These sensors, derived from integrated circuit technology, provide detailed patterns of interactions to micron-level (40 millionths of an inch) precision, with subnanosecond timing and low mass. The active area of these arrays has increased from a few square centimeters in experiments in the 1980s to 200 square meters in the CMS and ATLAS trackers at the Large Hadron Collider at CERN.

    CERN/CMS Detector

    CERN ATLAS Credit CERN SCIENCE PHOTO LIBRARY

    The CMS high-granularity calorimeter, or HGCal, will use 600 square meters of silicon. The precision of these detectors enables unique identification of heavy quarks (bottom and charm) that travel a fraction of a millimeter before they decay. The precision was crucial, for example, in the discoveries of the top quark in 1995, CP violation and mixing in the B meson system, and the Higgs boson in 2012.

    Research and development to improve the characteristics and develop better silicon detectors with the use of new technologies continue as we upgrade the existing detectors for better performance and develop designs for experiments at future generations of accelerators.

    1
    Working with collaborating laboratories and industrial partners, Fermilab researchers have developed and demonstrated the first three-layer 3-D bonded devices. This shows a three-layer 3-D chip stack. Image courtesy of Ron Lipton

    The 3-D integration of pixelated sensors with readout chips was an infant technology when we began R&D in 2006. The 3-D interconnection technique (now called hybrid bonding by the semiconductor industry) can replace the large, costly, solder bump interconnect technology with one that can be directly integrated into semiconductor process lines. It reduces the minimum spacing between pixels from about 50 microns to three, allows multilayer stacked connections through the body of the semiconductor, and dramatically reduces the capacitance of the interconnect, increasing speed and reducing electronic noise. Working with collaborating laboratories and industrial partners, we have developed and demonstrated the first three-layer 3-D bonded devices, with two electronics layers occupying only 35 microns in height, down from the usual hundreds. This hybrid bonding technology is now probably in your smart phone camera.

    2
    Schematic of the stacked layers. Image courtesy of Ron Lipton

    Future accelerators, including the High-Luminosity LHC, will produce collisions at a rate many times higher than the current LHC. The complexity of these collision events puts a premium on fast timing and recognition of very complex patterns of energy deposited in detectors. A possibility we are exploring is the induced-current detector. 3-D technology allows us to combine small pixels and low electronic noise with sophisticated electronics. The sensitivity and timing capabilities are now so good that we can measure the detailed shape of pulses due to charge movement deep in the silicon. This pattern of pulse shapes can give us much more information than the usual measurement of only the total charge. If this idea works, a single layer of silicon could measure timing to picoseconds, position to microns, as well as track angle, compressing multiple layers of sensor into one. This would greatly increase the power of detectors to select and process interesting events at very high speed. Work is under way on simulations of these effects and collaboration with industry on a 3-D demonstrator.

    Another way to address the experimental challenges is to improve the time resolution of silicon detectors. This can be done by designing the silicon to provide internal gain, providing a larger signal with a faster rise time. The low-gain avalanche diode, or LGAD, was designed to accomplish this. The LGAD is a new technology, and improved variants are continually emerging. Fermilab has an extensive program of testing and qualifying these LGAD detectors in bench tests and in the Fermilab Test Beam. The work is a close collaboration with the foundries and with other institutes within CMS and ATLAS. This program has been crucial in the validation and adoption of LGAD technology for the CMS upgrade endcap timing layer.

    The current generation of LGADs suffers from dead regions at the edges of each pixel and has only moderate radiation hardness. This limits the pixel size and range of applicability of these devices. By changing the top layers of the sensors (AC coupling) and adding a layer buried below the surface (buried gain layer) we can both eliminate most of the dead region and provide for a more well-defined gain that is also more resistant to radiation. First demonstrators are now being fabricated in collaboration with industry and universities.

    3
    Researchers are developing 8-inch sensors, seen here on a probe station at SiDet, for the CMS HGCal. Photo courtesy of Ron Lipton

    Finally, the very large area of the CMS HGCal prompted us to begin the development of large-area sensors, producing the first HEP sensors on 8-inch silicon wafers in collaboration with industry. We developed the process flow with colleagues from other laboratories and integrated designs from contributors all over the world. We have demonstrated high quality 8-inch sensors thinned to 200 microns.

    In this work, intense collaboration with the Fermilab ASIC group, support from CMS and DOE, infrastructure at SiDet, strong collaboration with laboratory, university and industrial partners, and the central contributions of summer students, graduate students, and postdocs have all been vital. These are all exciting developments and there is much more to do. As Richard Feynman said: “There is plenty of room at the bottom.”

    See the full here.


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    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 2:36 pm on June 11, 2020 Permalink | Reply
    Tags: , FNAL, , , Scientists studying the muon have been puzzled by a strange pattern in the way muons rotate in magnetic fields., This week an international team of more than 170 physicists published the most reliable prediction so far for the theoretical value of the muon’s anomalous magnetic moment.   

    From Fermi National Accelerator Lab: “Physicists publish worldwide consensus of muon magnetic moment calculation” 

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    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.

    June 11, 2020
    Jerald Pinson

    For decades, scientists studying the muon have been puzzled by a strange pattern in the way muons rotate in magnetic fields, one that left physicists wondering if it can be explained by the Standard Model — the best tool physicists have to understand the universe.

    This week, an international team of more than 170 physicists published the most reliable prediction so far for the theoretical value of the muon’s anomalous magnetic moment, which would account for its particular rotation, or precession. The magnetic moment of subatomic particles is generally expressed in terms of the dimensionless Landé factor, called g. While a number of international groups have worked separately on the calculation, this publication marks the first time the global theoretical physics community has come together to publish a consensus value for the muon’s magnetic moment [ https://arxiv.org/abs/2006.04822 ].

    The result differs from the most recent experimental measurement, which was performed at Brookhaven National Laboratory in 2004, but not significantly enough to unambiguously answer this question.

    Now the world awaits the result from Fermilab’s current Muon g-2 experiment. In the upcoming months, physicists working on the experiment will unveil their preliminary measurement for the value. Depending on how much the Standard Model theoretical calculation differs from the upcoming experimental measurement, physicists may be one step closer to determining whether the muon’s magnetic interactions are hinting at particles or forces that have yet to be discovered.

    1
    Today’s publication by the Muon g-2 Theory Initiative marks the first time the global theoretical physics community has come together to publish a consensus value for the muon’s magnetic moment. Now the world awaits the result from Fermilab’s current Muon g-2 experiment, whose magnetic storage ring is pictured here. Photo: Reidar Hahn, Fermilab.

    In the late 1960s at CERN laboratory, scientists began using a large circular magnetic ring to test the theory that described how muons should “wobble” when moving through a magnetic field. Since then, experimenters have continued to quantify that wobble, making more and more precise measurements of the muon’s anomalous magnetic moment.

    The decades-long effort eventually led to an experiment at Brookhaven National Laboratory and its successor at Fermilab, as well as plans for a new experiment in Japan. At the same time, theorists worked to improve the precision of their calculations and fine-tune their predictions.

    The theoretical value of the anomalous magnetic moment of the muon, published today, is:

    a = (g-2)/2 (muon, theory) = 116 591 810(43) x 10-12

    The most precise experimental result available so far is:

    a = (g-2)/2 (muon, expmt) = 116 592 089(63) x 10-12

    Again, the slight discrepancy between the experimental measurements and the predicted value has persisted, and again it is just beneath the threshold to make a definitive statement.

    This theoretical value, published in the arXiv [above], is the result of over three years of work by 130 physicists from 78 institutions in 21 countries.

    “We’ve not had a theory effort like this before in which all the different evaluations are combined into a single Standard Model prediction,” said Aida El-Khadra, a physicist at the University of Illinois and co-chair of the Steering Committee for the Muon g-2 Theory Initiative, the name of the group of scientists who worked on the calculation.

    Their work builds on a single equation published in 1928 that simultaneously started the field of quantum electrodynamics and laid the foundations for the Muon g-2 experiment.

    An elegant theory

    If you were to ask physicists what they considered the most accurate and successful equation in their field, chances are more than a few would say it’s Dirac’s equation, which describes the relativistic quantum theory of the electron. Published in 1928, Dirac described the spin motion of electrons, and his equation bridged the gap between Einstein’s theory of relativity and the theory of quantum mechanics, and unintentionally predicted the existence of antimatter with only a single equation.

    Dirac was also able to calculate something called the magnetic moment of the electron, which he described as being “an unexpected bonus.”

    Electrons can be thought of as tiny spinning tops that rotate on their axis, an intrinsic property that makes each electron act like a tiny magnet. When placed in a magnetic field, such as the ones generated in particle accelerators, electrons will precess — or wobble on their axis — in a specific and predictable pattern. This wobble is an effect of the particle’s magnetic moment, and it applies to more than electrons. Every electrically charged particle with ½ spin (spin is quantified in half units) behaves in the same way, including particles called muons, which have the same properties as electrons but are more than 200 times as massive.

    Dirac’s equation, which did not take into account the effects of quantum fluctuations, predicted that g would equal 2. Experiment has shown that the actual value differs from that simple expectation — hence the name “muon g-2.”

    Physicists now have a much better understanding of what those quantum fluctuations are and how they behave at subatomic scales, but precisely calculating how they affect the muon’s path is no easy task.

    “Calculating the effects of these quantum fluctuations at the precision level demanded by modern experiment isn’t something that one brilliant person can do alone,” El-Khadra said. “It really takes the whole village.”

    Meeting of the minds

    With so many physicists working on the latest developments to the theory around the world, El-Khadra and her colleagues at Fermilab knew the best way to facilitate interactions between the groups was to bring them all together. So, starting in 2016, El-Khadra and her colleagues in the Fermilab Theory Group, together with Brookhaven National Laboratory scientist Christoph Lehner, Theory Initiative co-chair, and several other international collaborators reached out to the leaders in the global community of physicists working on this problem to put together a new initiative, the Muon g-2 Theory Initiative. The initiative, led by a nine-person Steering Committee that includes leaders of all the major efforts in both theory and experiment, organized a series of workshops around the world, including in the U.S., Japan and Germany, the first of which was hosted at Fermilab in 2017.

    “We had some very intense discussions,” El-Khadra said, “That led to more detailed comparisons and a better understanding of the pros and cons of the various approaches.”

    The establishment of the Muon g-2 Theory Initiative was the first coherent international effort to bring together all of the parties working on the Standard Model value of the muon’s anomalous magnetic moment.

    “Before this initiative began, there were a number of evaluations in the literature of the Standard Model value, each of which differed slightly from the others,” said Boston University scientist Lee Roberts, co-founder of the Fermilab experiment and a member of the initiative’s Steering Committee. “The remarkable thing is that this worldwide community was able to come together and to agree on the ‘best’ value for each of the contributions to the value of the muon’s magnetic moment.”

    2
    Standard Model theory: The chart on the left shows the contributions to the value of the anomalous magnetic moment from the Standard Model of particles and interactions. About 99.994% comes from contributions due to the electromagnetic force while the hadronic contributions account for only 0.006% (note the blue sliver). The right chart shows the contributions to the total uncertainty in the theoretical prediction. About 99.95% of the total error in the theoretical prediction is due the uncertainties in the hadronic corrections, while, at about 0.05% of the total error, the uncertainties in the electromagnetic and electroweak contributions are negligibly small. (QED – quantum electrodynamic forces; EW – electroweak forces; HVP – hadronic vacuum polarization; HLbL – hadronic light-by-light). Image: Muon g-2 Theory Initiative.

    Quantum calculations

    “Muons and other spin-½ particles are never really alone in the universe,” said Fermilab scientist Chris Polly, who is one of Muon g-2’s spokespersons, along with University of Manchester physicist Mark Lancaster. “They interact with a whole entourage of particles that are constantly popping into and out of existence.”

    The two main sources of uncertainty are hadronic vacuum polarization and light-by-light scattering — in which a muon emits and reabsorbs photons after they have traveled through a bubble of quarks and gluons. Both of these factors combine to make up less than 0.01% of the effect on the muon’s wobble yet make up the main source of uncertainty in the theory calculation.

    Calculating the light-by-light scattering part of the hadronic contribution has proven to be especially difficult, and before the start of the Muon g-2 Theory Initiative, physicists had not yet produced reliable estimates of its effects. The best they could manage were rough approximations that led some to wonder whether these evaluations of the light-by-light scattering might be the source of the difference between the muon’s calculated anomalous magnetic moment and the experimentally measured value.

    But theorists are now confident that they can lay these doubts to rest. Thanks to heroic efforts in recent years within the theory community, not just one, but two independent evaluations are now available, each with reliably estimated uncertainties, which are included in the total error of the Standard Model prediction listed above.

    “We’ve now quantified the light-by-light scattering contribution to the extent that it can no longer be used as an explanation to save the Standard Model if the experimental value turns out to differ significantly from the theoretical prediction,” said Brookhaven National Laboratory physicist Christoph Lehner, Theory Initiative co-chair.

    And with so much riding on the line, El-Khadra and other members of the Theory Initiative have left nothing to chance.

    “We have strongly emphasized the importance of including evaluations based on several different methods in our construction of the Standard Model prediction of the anomalous magnetic moment of the muon,” El-Khadra said. “Because if we find that the Fermilab experiment’s measurement is inconsistent with the Standard Model, we want to be sure.”

    The Fermilab Muon g-2 experiment is supported by the DOE Office of Science.

    See the full here.


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    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 12:57 pm on June 3, 2020 Permalink | Reply
    Tags: , FNAL, , SENSEI collaboration   

    From Fermi National Accelerator Lab: “SENSEI gets quiet” 

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    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.

    June 3, 2020
    Sho Uemura

    What makes for a good dark matter detector? It has a lot in common with a good teleconference setup: You need a sensitive microphone and a quiet room.

    Scientists working on the SENSEI experiment at the Department of Energy’s Fermilab now have demonstrated for the first time a particle detector — based on charge-coupled device, or CCD, technology — with both the sensitivity and reduced background rates needed for an effective search for low-mass particles of dark matter, the mysterious substance that accounts for about 80 percent of all matter in the universe.

    1
    This picture shows the the new SENSEI skipper-CCD module. Image: SENSEI collaboration.

    The demonstration is important in two ways. First, the background rates measured by the SENSEI detector are record lows for a silicon detector. They set the world’s strongest limits on dark matter interactions with electrons, across a wide range of models. Second, it shows the high quality of the detectors that will be used in the full-scale SENSEI experiment under construction. SENSEI will run at the Canadian SNOLAB deep underground laboratory.

    SNOLAB, a Canadian underground physics laboratory at a depth of 2 km in Vale’s Creighton nickel mine in Sudbury, Ontario

    The SENSEI detector is a 5.4-megapixel CCD made of 2 grams of silicon currently operating about 100 meters underground at Fermilab. If a dark matter particle collides with one of the electrons in the silicon, the energy transferred to the electron may be enough to liberate it from the crystal structure of the silicon. If there is enough energy, additional electrons will be freed. This charge is the signal SENSEI scientists are looking for. The smaller the signal SENSEI can detect, the broader the range of dark matter models it can test.

    3
    This shows the SENSEI CCD module in the detector vessel. Photo: SENSEI collaboration.

    To observe small dark matter signals, the first thing scientists need is a sensitive detector. In other words, they must be able to detect a small signal and consistently distinguish it from a truly empty detector. As demonstrated in previous work, SENSEI’s skipper-CCDs, designed by Lawrence Berkeley National Laboratory, can count the exact number of electrons in each pixel.

    4
    In this test data, taken with a very long acquisition time, we plotted the measured charge in each pixel. The true charge is of course always an integer number of electrons. The measurement precision is a small fraction of an electron, so the 0-electron and 1-electron pixels are well separated, and there is no possibility of miscategorizing an empty pixel. Image: SENSEI collaboration.

    Second, scientists need low background — the rate of signal-like events from causes other than dark matter has to be small. A sensitive detector with high background is like a studio microphone in a noisy room. Even if the microphone can pick up a whisper, your soft voice might be drowned out by the noise of the washing machine in the background. The only way to improve the recording is to eliminate the noise of the washing machine.

    The SENSEI collaboration now has demonstrated for the first time that it has a sensitive dark matter detector and can reduce background rates. It’s important to demonstrate that a detector can achieve low background rates before you scale up to a larger experiment with the same technology, because otherwise you are just going to scale up your background rate. Previous dark matter searches by SENSEI used prototype CCDs, which had high sensitivity but also high backgrounds because they were not made with the highest-quality silicon.

    5
    SENSEI rules out the blue regions, where the rate of dark matter interactions would be larger than the event rate that SENSEI observes.
    Gray regions are ruled out by other experiments. The orange bands are favored by theoretical models and are targets for the full-scale SENSEI experiment. Image: SENSEI collaboration.

    SENSEI’s new dark matter search has yielded the first result from its new science-grade CCDs, which were fabricated in a dedicated production run for SENSEI with high-quality silicon. The collaboration also reduced the amount of radiation that hits the CCD by adding extra shielding around the experiment. The result was a decrease in background event rates compared to the previous search with a prototype CCD. The rate of single-electron events decreased from 33,000 to 450 events/gram-day, and we see fewer two-electron events (five, down from 21) in a much larger exposure (2.09 gram-days, up from 0.043). We also see no three- or four-electron events — just as in the previous search, but with a larger exposure.

    The science-grade CCDs work as well as could have been hoped, and SENSEI expects background rates to be even lower at SNOLAB. There will likely be more great science from SENSEI in the near future!

    Learn more from SENSEI’s preprint or the collaboration’s presentation at a seminar at Fermilab.

    See the full here.


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    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 11:40 am on May 12, 2020 Permalink | Reply
    Tags: "Why DUNE? Searching for the origin of matter", , FNAL, , ,   

    From Sanford Underground Research Facility: “Why DUNE? Searching for the origin of matter” 

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    From Sanford Underground Research Facility


    Homestake Mining Company

    May 11, 2020
    Erin Lorraine Broberg

    1
    DUNE science goal icon: Origin of matter.Credit: Fermilab

    Why does matter exist? It may seem like a strange question, but according to current models of the early universe, matter shouldn’t exist.

    “According to what we know about the laws of physics, the amount of matter in the universe should be, effectively, zero,” said André de Gouvêa, a theoretical physicist with the DUNE collaboration and professor at Northwestern University.

    In physics, the discrepancy between what we see—a universe filled with galaxies and a planet teeming with life—and what models predict we should see—absolutely nothing—is called the “matter-antimatter asymmetry problem.” The international Deep Underground Neutrino Experiment, or DUNE, hosted by the Department of Energy’s Fermilab and to be built at Fermilab and Sanford Lab, seeks to solve this problem, which has dogged physicists for nearly a century.

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


    The Deep Underground Neutrino Experiment will measure neutrino oscillations by studying a neutrino that will be sent from Fermilab to the DUNE detectors at the Sanford Underground Neutrino Facility. The experiment will use a muon neutrino beam created at Fermilab’s Long-Baseline Neutrino Facility and send it 800 miles/1300 kilometers straight through the earth to South Dakota. By the time the neutrinos arrive in South Dakota, only a small fraction of neutrinos will be detected as muon neutrinos. Most neutrinos will interact as electron and tau neutrinos. Graphic courtesy Fermilab

    A universe-sized problem

    Despite what the models predict, we find ourselves amidst a universe replete with matter. Everything we see around us is made from just a few types of fundamental particles. Combined, they form protons and neutrons which join up with electrons to form atoms, which in turn bind to make molecules, building ever larger.

    But these key ingredients are only half the story.

    In the 1930s, physicists discovered “antiparticles” that mirror the fundamental particles. Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Just like matter particles, antimatter particles could combine to build bigger and bigger units of antimatter—if they ever survived long enough do to so.

    Although matter and antimatter particles are nearly indistinguishable, the two forms do not coexist peacefully. When antimatter comes into contact with regular matter, particles and antiparticles immediately annihilate, leaving leaving pure energy in their wake.

    This complete, mutual annihilation is the impetus of the matter-antimatter asymmetry problem. Our current models dictate that the Big Bang created equal parts matter and antimatter. Within a second, all the matter and antimatter should have met and annihilated, leaving behind a universe with nothing but energy in the form of light.

    2
    Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Graphic courtesy Fermilab

    “The problem is, if we take our favorite model and calculate the evolution of the universe, we get a prediction that is completely off,” de Gouvêa said. “There should not be any matter in the universe we live in today.”

    We know, of course, that this didn’t happen. We live in a matter-dominated universe with swirling galaxies, innumerable stars and at least one life-sustaining planet. Somehow, about one billionth of the total amount of matter created in the Big Bang managed to evade annihilation and fill the universe with the matter we see today. Thus, the matter-antimatter asymmetry problem.

    Physicists believe there is an undiscovered mechanism, hidden in the wrinkles of nature’s laws, that gave matter an initial advantage over antimatter. And for nearly a century, they’ve been trying to pinpoint it.

    A crack in nature’s symmetry

    Because matter and antimatter are mirror images of each other, physicists assumed that the laws of nature applied to both matter particles and antimatter particles in the exact same way. In physics, this type of equality is called a “symmetry.”

    According to this idea, weak and strong forces should bind particles and antiparticles without discrimination. Gravity should pull on antimatter with the same force it exerts on matter. Magnets should attract oppositely charged particles and antiparticles with the same gusto. In fact, an entire universe made of antimatter should look identical to the one we live in today.

    This assumption of a perfect symmetry among the fundamental building blocks of the universe held true until the 1960s, when James Cronin and Val Fitch made the shocking discovery that, in a very specific case, the universe treats matter slightly different than antimatter.

    Their Nobel Prize-winning experiment examined the way that quarks (fundamental particles that make up protons and neutrons) and antiquarks (their corresponding antiparticles) interacted with the weak force. Rather than treating quarks and antiquarks the same way, the weak force favored quarks in an infamous violation of what is called the Charge Parity (CP) symmetry.

    In other words, the universe had revealed a slight preference for matter over antimatter.

    3
    CP violation experiment: In 1963, a beam from BNL’s Alternating Gradient Synchrotron and the pictured detectors salvaged from the Cosmotron were used to prove the violation of conjugation (C) and parity (P) – winning the Nobel Prize in physics for Princeton University physicists James Cronin and Val Fitch. Photo courtesy Brookhaven National Laboratory.

    This discovery stunned the particle physics community. In the decades that followed, researchers continued to make precision measurements of these decays, combing their data for new physics that might be lurking within this phenomenon. Thirty years after Cronin and Fitch’s discovery, Elizabeth Worcester was making such measurements at Fermilab’s Tevatron with the KTeV experiment.

    “In the 1990s, we were studying the same decays in which CP violation was first observed,” said Worcester, who is now a DUNE physcis co-coordinator and physicist at Brookhaven National Laboratory.

    This glitch in the laws of nature specifically caught the attention of physicists studying the imbalance of matter and antimatter in the universe. Was this violation of CP symmetry the mechanism that allowed some matter to escape annihilation after the Big Bang?

    Subsequent experiments combined with more and more sophisticated calculations demonstrated that nature’s unequal treatment of quarks and antiquarks is not quite big enough to account for the gaping discrepancy we see today.

    However, scientists think the existence of CP violation is a major clue.

    “This violation could mean there is something very fundamental about the laws of nature that we are missing,” de Gouvêa said.

    As soon as Cronin and Fitch made their discovery, physicists began to wonder if other fundamental particles broke the same symmetry. Perhaps multiple sources of CP violation, when combined, could explain how so much matter escaped annihilation in the early universe.

    By finding another, even bigger crack in this symmetry, physicists aim to prove that the universe has an overarching preference for matter, making our current universe possible.

    A ghost-like candidate

    If quarks didn’t provide enough CP violation in the early universe, could another category of elementary particles known as neutrinos have provided another way to favor matter over antimatter?

    “If you look at everything that we’ve learned about neutrinos so far, it indicates that CP could be violated in the neutrino sector,” de Gouvêa said. “There is no specific reason to expect it not to be violated.”

    Neutrinos are extremely challenging to work with. Trillions of these particles pass through you each second. Their miniscule mass and neutral charge make them almost impossible to detect. Building an experiment to test whether these ghost-like particles violate the CP symmetry is even more ambitious.

    “The reason we don’t know if neutrinos violate CP symmetry is purely an experimental issue,” said Ryan Patterson, DUNE physics co-coordinator and professor of physics at the California Institute of Technology (Caltech). “Neutrinos could violate CP a lot, but we don’t know yet because the experiments up to this point haven’t been sensitive enough.”

    One peculiar property of neutrinos, however, makes the DUNE experiment possible. As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation.

    4
    As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation. Graphic courtesy Fermilab

    “In regard to neutrinos, we only have one realistic way of measuring CP violation: it will show itself in the way neutrinos oscillate between flavors,” de Gouvêa said.

    In principle, the measurement is quite simple, according to de Gouvêa.

    “You simply compare a matter process with an antimatter process, and then you ask if they agree,” de Gouvêa said. To measure the CP violation, researchers must compare the oscillations of neutrinos with the oscillations of antineutrinos. If there is a discrepancy in the way they oscillate over a distance, then neutrinos break the symmetry.

    The difficult part of the experiment is that neutrino oscillations occur over hundreds of miles. To measure a deviation or discrepancy, researchers would need… well, they would need to build a long-baseline neutrino facility.

    Are neutrinos the reason we exist?

    The particulars of this universe-sized mystery have guided the design of the aptly named Long-Baseline Neutrino Facility (LBNF), which will house the Deep Underground Neutrino Experiment. Stretching across the Midwest, with infrastructure located at Fermilab in Batavia, Illinois and at Sanford Lab in Lead, South Dakota, the facility allows researchers to measure just how neutrinos and antineutrinos oscillate over long distances.

    It works like this: a particle accelerator will generate intense beams of neutrinos and antineutrinos at Fermilab. The beams will travel 800 miles straight through rock and earth – no tunnel needed – to enormous particle detectors located deep underground at Sanford Underground Research Facility (Sanford Lab), where 4,850 feet of rock overburden shield the detectors from unwanted background signals.

    During their trip through the Earth’s crust—which takes just four milliseconds—the neutrinos and antineutrinos will oscillate, changing from one flavor into another. Conveniently, the distance between Fermilab and Sanford Lab is ideal for this measurement; by the time the particles arrive at Sanford Lab, their oscillations will be at their peak.

    “To get the best measurement, we put the detectors right where we expect the oscillation to be maximal,” Patterson said.

    When the beam reaches Sanford Lab, some of the neutrinos and antineutrinos will collide with argon atoms inside the detectors. These collisions result in unique signals. By measuring and comparing hundreds of these signals, researchers will be able to tell if neutrinos and antineutrinos oscillate in different ways – the sure-tell sign of CP symmetry violation – and if so, by how much.

    “I think what the neutrinos are going to tell us could change our understanding of nature in a very interesting way,” de Gouvêa said.

    So, why DUNE? In a nutshell, it could help scientists answer one of the big unsolved questions in science and give all of us an answer to the reason we—and everything else in the universe—exists.

    That, however, is only part of the story. Stay tuned for part II of our series of stories about the science of DUNE.

    See the full article here .


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

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

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

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

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

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

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

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

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

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

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

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

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


    LBNE

    U Washington Majorana Demonstrator Experiment at SURF

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

    CASPAR at SURF


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

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

     
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