Stephen Sekula steve@hub.polari.us

Dallas, TX, USA

Husband; Associate Professor of Physics; I teach at SMU in Dallas, TX; I study the Higgs Particle with the ATLAS Experiment at the Large Hadron Collider at CERN; writer and blogger; drummer; programmer; teacher; scientist; traveler; runner; gardener; open-source aficionado.

  • at 2021-04-02T01:58:54Z

    Bus Ride Buddy 公車旅伴

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  • Astronomy Picture of the Day for 2021-03-31 12:30:01.412753

    Astronomy Picture of the Day (Unofficial) at 2021-03-31T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 31
    Polarization of light emitted from the near the black hole M87 is pictured. See Explanation.

    M87's Central Black Hole in Polarized Light
    Image Credit: Event Horizon Telescope Collaboration; Text: Jayanne English (U. Manitoba)

    Explanation: To play on Carl Sagan’s famous words "If you wish to make black hole jets, you must first create magnetic fields." The featured image represents the detected intrinsic spin direction (polarization) of radio waves. The polarizationi is produced by the powerful magnetic field surrounding the supermassive black hole at the center of elliptical galaxy M87. The radio waves were detected by the Event Horizon Telescope (EHT), which combines data from radio telescopes distributed worldwide. The polarization structure, mapped using computer generated flow lines, is overlaid on EHT’s famous black hole image, first published in 2019. The full 3-D magnetic field is complex. Preliminary analyses indicate that parts of the field circle around the black hole along with the accreting matter, as expected. However, another component seemingly veers vertically away from the black hole. This component could explain how matter resists falling in and is instead launched into M87’s jet.

    Tomorrow's picture: cleaning mars


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Astronomy Picture of the Day for 2021-03-21 12:30:01.987368

    Astronomy Picture of the Day (Unofficial) at 2021-03-21T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 21
    The ancient Antikythera mechanism is shown, the oldest known orrery. See Explanation.

    The Antikythera Mechanism
    Image Credit & License: Marsyas, Wikipedia

    Explanation: No one knew that 2,000 years ago, the technology existed to build such a device. The Antikythera mechanism, pictured, is now widely regarded as the first computer. Found at the bottom of the sea aboard a decaying Greek ship, its complexity prompted decades of study, and even today some of its functions likely remain unknown. X-ray images of the device, however, have confirmed that a main function of its numerous clock-like wheels and gears is to create a portable, hand-cranked, Earth-centered, orrery of the sky, predicting future star and planet locations as well as lunar and solar eclipses. The corroded core of the Antikythera mechanism's largest gear is featured, spanning about 13 centimeters, while the entire mechanism was 33 centimeters high, making it similar in size to a large book. Recently, modern computer modeling of missing components is allowing for the creation of a more complete replica of this surprising ancient machine.

    Tomorrow's picture: surround orion


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Astronomy Picture of the Day for 2021-03-08 12:30:02.356952

    Astronomy Picture of the Day (Unofficial) at 2021-03-08T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 March 8
    See Explanation.
Moving the cursor over the image will bring up an annotated version.
Clicking on the picture will download
the highest resolution version available.

    Three Tails of Comet NEOWISE
    Image Credit & Copyright: Nicolas Lefaudeux

    Explanation: What created the unusual red tail in Comet NEOWISE? Sodium. A spectacular sight back in the summer of 2020, Comet NEOWISE, at times, displayed something more than just a surprisingly striated white dust tail and a pleasingly patchy blue ion tail. Some color sensitive images showed an unusual red tail, and analysis showed much of this third tail's color was emitted by sodium. Gas rich in sodium atoms might have been liberated from Comet NEOWISE's warming nucleus in early July by bright sunlight, electrically charged by ultraviolet sunlight, and then pushed out by the solar wind. The featured image was captured in mid-July from Brittany, France and shows the real colors. Sodium comet tails have been seen before but are rare -- this one disappeared by late July. Comet C/2020 F3 (NEOWISE) has since faded, lost all of its bright tails, and now approaches the orbit of Jupiter as it heads back to the outer Solar System, to return only in about 7,000 years.

    Astrophysicists: Browse 2,400+ codes in the Astrophysics Source Code Library
    Tomorrow's picture: mars 360


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Searching for Higgs boson twins

    ParticleNews at 2021-02-25T16:27:38Z

    "Searching for Higgs boson twins"

    Higgs-boson pairs could help scientists understand the stability of our universe. The trick is finding them.

    Particle collision visualization

    In 2012, scientists on the CMS and ATLAS experiments at CERN’s Large Hadron Collider discovered the Higgs boson. Now, they’re looking for two Higgs bosons born from a single collision.

    “The Higgs self-coupling has implications in understanding the origin and ultimate fate of the universe,” says Nan Lu, a postdoc at the California Institute of Technology supported by the US Department of Energy’s Office of Science. “This process is a lighthouse that guides the future of particle physics.”

    Higgs bosons are the physical manifestations of the Higgs field, an invisible medium that is woven into the fabric of spacetime.

    “Elementary particles obtain their masses through interaction with this Higgs field,” Lu says. “Without the Higgs field, all elementary particles would be massless and traveling at the speed of light. The universe would not look the same as it does today.”

    The LHC can generate Higgs bosons by colliding protons and transmitting the stored energy into the Higgs field—much like a pebble striking the surface of a river and transferring its kinetic energy into a ripple. This process happens at a rate of about one in a billion collisions.

    On even rarer occasions, this energy transfer can generate not one but two Higgs bosons at the same time. These Higgs boson twins could help scientists characterize a largely unmeasured facet of the Higgs mechanism: the shape of the Higgs potential.

    The boson, the field and the Higgs potential

    The Brout-Englert-Higgs mechanism—to use its full name—consists of three interlinking facets: the Higgs boson, the Higgs field and the Higgs potential.

    “You can think about it like a river,” says Irene Dutta, a graduate student at Caltech. “The Higgs boson is a ripple, the Higgs field is the water, and the Higgs potential is the shape of the riverbed.”

    The Higgs boson—the ripple—gives scientists a glimpse of the otherwise invisible Higgs field—the water. But underneath it all is the Higgs potential—the riverbed, or a mathematical function that determines the different possible energy states of the Higgs field.

    “A river might seem calm and flat,” Dutta says, “but there could be a waterfall that leads to much lower ground that we cannot see from where we are.”

    If the potential dropped and the Higgs field spontaneously fell into a lower energy state, the universe as we know it would evaporate.

    “The current calculations indicate that we could be living in a false vacuum,” says Thong Nguyen, a graduate student at Caltech. “This means that at any moment, the Higgs field could tunnel through the potential barrier to a true negative-energy vacuum, creating an expanding singularity bubble that eventually swallows up the entire universe.”

    (The universe has yet to disappear in its 14 billion years, at least, and physicists do not anticipate that it will happen anytime soon.)

    The origin of matter

    According to Nguyen, the Higgs field has already fallen from a high energy state into a lower one once before.

    “Right after the Big Bang, when the universe was a hot and dense soup, the Higgs field was perfectly symmetrical and did not interact with other particles,” Nguyen says. “But as the universe cooled, the Higgs field underwent a phase transition. Symmetry broke, and then particles were able to interact with the Higgs field to acquire mass.”

    This first transition could be the missing link in one of the biggest mysteries in physics: the dominance of matter over its equal-and-opposite counterpart, antimatter.

    “Right after the Big Bang, we should have had equal amounts of matter and antimatter,” Lu says. “Today, there is a large amount of matter and almost no antimatter.”

    The evolution of the Higgs field during the primordial universe could be responsible for this imbalance.

    “If it’s a smooth transition, as our models predict, then the entire Higgs field would have cooled homogeneously, like water slowly freezing into ice,” Nguyen says. “But if it’s an abrupt transition, then bubbles could have formed and eventually expanded to fill the entire universe.”

    These bubbles in the Higgs field could have serendipitously sheltered the small excess of matter that eventually formed everything.

    Higgs self-coupling

    The Higgs potential regulates the behavior of Higgs bosons, including their interactions with one another. If scientists can find and study Higgs-boson pairs, then they can work backwards and indirectly probe the Higgs potential’s shape.

    “First we need to measure the rate of Higgs-boson pair production,” Lu says. “Then we want to measure the properties of these two Higgs bosons.”

    The scarcity of this process makes it a classic needle-in-a-haystack problem.

    “During Run II [which ended in December 2018], the LHC would have generated about 7.5 million Higgs bosons,” Dutta says. “But it would have only produced about 4500 Higgs-boson pairs.”

    Higgs bosons are notoriously difficult to separate from look-alike subatomic processes. Even for a very clean signature—a Higgs boson decaying into two photons—there are 10 identical background events for every real Higgs boson.

    “We’re completely swamped by the background,” Dutta says. “The di-Higgs production process is not an easy observation to make and our best chance of seeing it is with the High-Luminosity LHC upgrade,” now in full progress. 

    Once this upgrade is completed later this decade, future runs will increase the total number of potential collisions scientists have to study by at least a factor of 10.

    The overall US contributions to the LHC experimental research program and HL-LHC upgrade are funded by the US Department of Energy and the National Science Foundation. With the HL-LHC only a few years away, scientists are already honing their analysis methods.

    They have begun to apply machine-learning techniques inspired by natural language processing. Nguyen is developing and training machine-learning algorithms to recognize the subtle differences between Higgs boson signatures and look-alike background processes (much like a natural-language-processing algorithm separates similar sounding words like “close” and “clothes.”)

    “We can treat each particle like a word in a sentence,” Nguyen says.

    Currently, scientists are working with only a few signatures for Higgs-boson pairs, but they hope to study more complex signatures over the next few years.

    “This research is still in the early stages but moving very fast,” Lu says.

    https://www.symmetrymagazine.org/article/searching-for-higgs-boson-twins?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

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  • Astronomy Picture of the Day for 2021-02-25 12:30:02.453590

    Astronomy Picture of the Day (Unofficial) at 2021-02-25T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 February 25
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    A Venus Flyby
    Image Credit: NASA, JHUAPL, Naval Research Lab, Guillermo Stenborg and Brendan Gallagher

    Explanation: On a mission to explore the inner heliosphere and solar corona, on July 11, 2020 the Wide-field Imager on board NASA's Parker Solar Probe captured this stunning view of the nightside of Venus at distance of about 12,400 kilometers (7,693 miles). The spacecraft was making the third of seven gravity-assist flybys of the inner planet. The gravity-asssist flybys are designed to use the approach to Venus to help the probe alter its orbit to ultimately come within 6 million kilometers (4 million miles) of the solar surface in late 2025. A surprising image, the side-looking camera seems to peer through the clouds to show a dark feature near the center known as Aphrodite Terra, the largest highland region on the Venusian surface. The bright rim at the edge of the planet is nightglow likely emitted by excited oxygen atoms recombining into molecules in the upper reaches of the atmosphere. Bright streaks and blemishes throughout the image are likely due to energetic charged particles, and dust near the camera reflecting sunlight. Skygazers from planet Earth probably recognize the familiar stars of Orion's belt and sword at lower right.

    Tomorrow's picture: fly over


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Astronomy Picture of the Day for 2021-02-20 12:30:02.254814

    Astronomy Picture of the Day (Unofficial) at 2021-02-20T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 February 20
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Perseverance: How to Land on Mars
    Image Credit: NASA, JPL, Mars 2020

    Explanation: Slung beneath its rocket powered descent stage Perseverance hangs only a few meters above the martian surface, captured here moments before its February 18 touchdown on the Red Planet. The breath-taking view followed an intense seven minute trip from the top of the martian atmosphere. Part of a high resolution video, the picture was taken from the descent stage itself during the final skycrane landing maneuver. Three taut mechanical cables about 7 meters long are visible lowering Perseverance, along with an electrical umbilical connection feeding signals (like this image), to a computer on board the car-sized rover. Below Perseverance streamers of martian dust are kicked-up from the surface by the descent rocket engines. Immediately after touchdown, the cables were released allowing the descent stage to fly to a safe distance before exhausting its fuel as planned.

    Tomorrow's picture: the stars in a rose


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  • JanKusanagi at 2021-02-18T09:55:56Z

    Regardless of what total idiots who hate our planet are saying...🙄

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  • Astronomy Picture of the Day for 2021-02-18 12:30:02.223417

    Astronomy Picture of the Day (Unofficial) at 2021-02-18T18:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2021 February 18
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Swiss Alps, Martian Sky
    Image Credit & Copyright: Jens Bydal

    Explanation: Taken on February 6, this snowy mountain and skyscape was captured near Melchsee-Frutt, central Switzerland, planet Earth. The reddish daylight and blue tinted glow around the afternoon Sun are colors of the Martian sky, though. Of course both worlds have the same Sun. From Mars, the Sun looks only about half as bright and 2/3 the size compared to its appearance from Earth. Lofted from the surface of Mars, fine dust particles suspended in the thin Martian atmosphere are rich in the iron oxides that make the Red Planet red. They tend to absorb blue sunlight giving a red tinge to the Martian sky, while forward scattering still makes the light appear relatively bluish near the smaller, fainter Martian Sun. Normally Earth's denser atmosphere strongly scatters blue light, making the terrestrial sky blue. But on February 6 a huge cloud of dust blown across the Mediterranean from the Sahara desert reached the Swiss Alps, dimming the Sun and lending that Alpine afternoon the colors of the Martian sky. By the next day, only the snow was left covered with reddish dust.

    News from Mars: NASA Perseverance Coverage
    Tomorrow's picture: pixels from space


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  • New strategy for Latin American physics

    ParticleNews at 2021-02-16T16:28:04Z

    "New strategy for Latin American physics"

    Scientists in Latin America recently published the first coordinated plan for the region’s research in high-energy physics, astrophysics and cosmology.

    Illustration: LASF4RI labeled watering can fostering science in South America

    Latin American scientists have completed their roadmap for the next five years of physics research, marking the end of a two-year grassroots effort to plan for the future of experiments and partnerships in the region.

    “One of the main goals was to find where collaboration could generate more impact for Latin American contributions to physics,” says Marcela Carena, head of the Theoretical Physics Department at the US Department of Energy’s Fermi National Accelerator Laboratory. “At this moment, there’s been no other Latin American body to guide such a strategic plan for the scientific community.”

    Carena, originally from Argentina, was one of the 23 members of the Latin American Strategy Forum for Research Infrastructure (LASF4RI) preparatory group, the team responsible for collecting input from the Latin American and international theoretical and experimental physics community in three pilot areas of research: high-energy physics, astrophysics and cosmology. The scientists on the team represented 10 countries in the region—Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Mexico, Peru, Paraguay and Venezuela—as well as Japan, Europe (as represented by CERN) and the United States.

    Illustration:
    Illustration by Sandbox Studio, Chicago with Pedro Rivas

    A plan for science and infrastructure

    The final report contains 10 recommendations, beginning with a push for continued support of current and future projects in cosmology and astrophysics, ranging from those already in operation—such as Pierre Auger Observatory in Argentina—and those planned for the near-term—such as the BINGO telescope in Brazil and Vera Rubin Observatory in Chile—to those planned for start-up more than a decade from now—such as the South American Gravitational-Wave Observatory. 

    Latin America is known for its clear skies and powerful telescopes; it provides the location for crucial observations that form many astrophysics and cosmology experiments. 

    “There are a series of projects that are already being built in Latin America and will become operational in 2025 or 2026,” says Marta Losada, originally from Colombia and more recently a professor of physics and the dean of science at New York University Abu Dhabi, who chaired the preparatory group. “So that’s a high priority.”

    Another high priority named in the report is ANDES, an underground laboratory proposed to be built in a tunnel connecting Argentina and Chile. The laboratory, protected from cosmic radiation that hits the planet’s surface, would allow scientists around the world to investigate dark matter and neutrinos, as well as conduct experiments in biology and geology. 

    “You need to start building the capacity and the expertise for those experiments now, if you want to build them in the region,” Losada says.

    The strategy identifies as areas of strength for the Latin American high-energy physics community both its involvement in collider physics, through international experiments at the Large Hadron Collider at CERN, and its involvement in neutrino physics, through the international Deep Underground Neutrino Experiment, managed by Fermilab. 

    “This is important for both Europe and the United States, because Latin American scientists have been contributing for decades,” Carena says. “But this plan will allow a higher level of coordination and will allow Latin American scientists to be better contributors to international large-scale experiments.”

    The report also describes the need to improve the region’s computing infrastructure and internet connectivity. The report says it is “fundamental to all experimental efforts” and will help scientists process the vast amounts of data generated at research sites, such as the under-construction Vera Rubin Observatory and the planned Cherenkov Telescope Array, both in Chile.

    Support for stronger connections

    By developing research infrastructure, encouraging global scientific participation and offering training opportunities, the report authors write that these efforts will help inspire future Latin American scientists and work to impede the “‘brain draining effect’ in the region.” 

    The LASF4RI group also mentioned the need to help scientists align their research with funding options, which can be tough to navigate. “Latin America is a complex environment with many countries and many different funding agencies,” Carena says.

    Prior to publishing the final report, the authors presented their recommendations to government officials and leaders of funding agencies in Latin America on October 27, 2020. Afterward, the officials at the fourth Iberoamerican Science and Technology Ministerial Meeting issued a declaration.

    Carena says the declaration provides national and international validation for the work of local scientists, labs and universities. Losada adds that “it was important to reflect the size of the growing community of Latin American physicists, and for us to demonstrate how you should continue to protect that investment in knowledge and resources.” 

    Illustration of a scientist by a calendar labeled with ANDES
    Illustration by Sandbox Studio, Chicago with Pedro Rivas

    A regional roadmap

    Latin American physicists began brainstorming what might go into a formal regional strategy—inspired by the longer-term plans developed for Europe and the United States—at professional conferences going back to 2016. And in early 2019, LASF4RI held its first workshops to create such a plan

    “Before this, we really hadn’t even worked out our main areas of research in Latin America or our strengths very clearly. These are really important, deep questions,” Losada says.

    Through extensive consultation and meetings, the team worked with physicists across disciplines to come up with the final recommendations. In 2020, the committee adjusted their meetings as the pandemic forced them to replace international in-person gatherings with Zoom calls.

    The preparatory group reached out to scientific societies, gathered 40 scientific white papers, and then submitted a draft report to a high-level review by scientists outside the preparatory group. 

    With an endorsement from the reviewers, the LASF4RI group finalized their report in November 2020.

    https://www.symmetrymagazine.org/article/new-strategy-for-latin-american-physics?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

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  • Jason Self at 2021-02-15T14:49:55Z

    This is so very true.

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  • Dr. Nigel Smith appointed as next Director of TRIUMF

    ParticleNews at 2021-02-12T16:27:45Z

    "Dr. Nigel Smith appointed as next Director of TRIUMF"

    Dr. Nigel Smith appointed as next Director of TRIUMF Press Releasexeno Fri, 02/12/2021 - 08:02521

    Dr. Nigel Smith

    VANCOUVER, B.C. – Dr. Nigel Smith, Executive Director of SNOLAB, has been selected to serve as the next Director of TRIUMF. Succeeding Dr. Jonathan Bagger, who departed TRIUMF in January 2021 to become CEO of the American Physical Society, Dr. Smith's appointment comes as the result of a highly competitive, six-month international search. Dr. Smith will begin his 5-year term as TRIUMF Director on May 17, 2021.

    "I am truly honoured to have been selected as the next Director of TRIUMF," said Dr. Smith. "I have long been engaged with TRIUMF's vibrant community and have been really impressed with the excellence of its science, capabilities and people. TRIUMF plays a unique and vital role in Canada's research ecosystem, and I look forward to continuing the legacy of excellence upheld by Dr. Jonathan Bagger and the previous TRIUMF Directors". 

    Founded in 1968, TRIUMF is Canada's particle accelerator centre. A multidisciplinary laboratory, TRIUMF is an international hub for discovery and innovation – pushing frontiers in research while training the next generation of leaders in science, medicine, and business. This breadth and impact are what attracted Dr. Smith to the role of Director, stating, "TRIUMF has an amazing portfolio of research covering fundamental and applied science that also delivers tangible societal impact through its range of medical and commercialisation initiatives. I am extremely excited to have the opportunity to lead a laboratory with such a broad and world-leading science program."

    "Nigel brings all the necessary skills and background to the role of Director," said Dr. Digvir Jayas, Interim Director of TRIUMF, Chair of the TRIUMF Board of Management, and Vice-President, Research and International at the University of Manitoba. "As Executive Director of SNOLAB, Dr. Smith is both a renowned researcher and experienced laboratory leader who offers a tremendous track record of success spanning the local, national, and international spheres. The Board of Management is thrilled to bring Nigel's expertise to TRIUMF so he may help guide the laboratory through many of the exciting developments on the horizon."

    Dr. Smith joins TRIUMF at an important period in the laboratory's history, as the organization moves into the second year of its current Five-Year Plan (2020-2025) and prepares to usher in a new era of science and innovation that will include the completion of two major projects: the Advanced Rare Isotope Laboratory (ARIEL) and the Institute for Advanced Medical Isotopes (IAMI). This new infrastructure, alongside TRIUMF's existing facilities and world-class research programs, will solidify Canada's position as a global leader in both fundamental and applied research. Dr. Smith expressed his optimism for TRIUMF, saying, "I am delighted to have this opportunity, and it will be a pleasure to lead the laboratory through this next exciting phase of our growth and evolution."

    About Nigel Smith

    Nigel Smith has served as SNOLAB as Director since July 2009. He currently holds a full Professorship at Laurentian University, adjunct Professor status at Queen's University, and a visiting Professorial chair at Imperial College, London. He received his Bachelor of Science in physics from Leeds University in the U.K. in 1985 and his Ph. D. in astrophysics from Leeds in 1991. He has served as a lecturer at Leeds University, a research associate at Imperial College London, group leader (dark matter) and deputy Division Head at the STFC Rutherford Appleton Laboratory before relocating to Canada to oversee the SNOLAB deep underground facility. 

    Dr. Smith has undertaken astroparticle physics research in extreme locations throughout his career, studying astronomical sources of ultra-high energy gamma rays using a telescope at the South Pole, searching for Galactic dark matter using detectors located 1100m underground at the Boulby facility in the U.K., and subsequently overseeing dark matter and neutrinos studies 2km underground at the SNOLAB facility in Canada. In 1987 he "wintered-over" as the sole operator of the telescope at the Amundsen-Scott South Pole station, being the first Briton to successfully winter at the Pole itself. 

    About TRIUMF 

    Established in 1968 in Vancouver, TRIUMF is Canada's particle accelerator centre. The lab is a hub for discovery and innovation inspired by a half-century of ingenuity in answering nature's most challenging questions. From the hunt for the smallest particles in our universe to research that advances the next generation of batteries or develops isotopes to diagnose and treat disease, TRIUMF drives more than scientific discovery. Powered by its complement of top talent and advanced accelerator infrastructure, TRIUMF is pushing the frontiers in isotope science and innovation, as well as technologies to address fundamental and applied problems in particle and nuclear physics, and the materials and life sciences. In collaboration with 21 Canadian universities, TRIUMF's diverse community of nearly 600 multidisciplinary researchers, engineers, technicians, tradespeople, staff, and students create a unique incubator for Canadian excellence, as well as a portal to premier global collaborations. Our passion for understanding everything from the nature of the nucleus to the creation of the cosmos sparks imagination, inspiration, improved health, economic opportunity, and a better world for all.

    www.triumf.ca

    @TRIUMFLab

    TRIUMF

    The interior vacuum

    The interior vacuum "tank" of TRIUMF's main cyclotron, the largest in the world. (Courtesy of TRIUMF)

    TRIUMF is one of the world’s leading subatomic physics laboratories. It brings together dedicated physicists and interdisciplinary talent, sophisticated technical resources, and commercial partners in a way that has established the laboratory as a global model of success. Its large user community is composed of international teams of scientists, post-doctoral fellows, and graduate and undergraduate students.

    4004 Wesbrook Mall
    VancouverBCV6T 2A3
    Canada

    604.222.1047

    http://www.triumf.ca/

    Stu Shepherd
    Communications Specialist

    t +1 604.222.7528

    sshepherd@triumf.ca

    https://www.interactions.org/press-release/dr-nigel-smith-appointed-next-director-triumf

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  • JanKusanagi at 2021-02-12T19:23:32Z

    PATHETIC, is what that was.

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  • ATLAS finds evidence of a rare Higgs boson decay

    ParticleNews at 2021-02-08T14:28:20Z

    "ATLAS finds evidence of a rare Higgs boson decay"

    ATLAS finds evidence of a rare Higgs boson decay katebrad Mon, 02/08/2021 - 09:33

    ATLAS event display: Higgs boson candidates decaying to a dilepton pair and a photon
    A collision event captured by the ATLAS detector in 2017 featuring a photon and two highly-collimated muons. The invariant mass of the dimuon pair is 0.6 GeV, and the invariant mass of the photon-plus-dimuon system is 124.9 GeV. The signature is consistent with a Higgs boson decaying to a dilepton pair and a photon. (Image: CERN)

    Since the discovery of the Higgs boson in 2012, scientists in the ATLAS and CMS collaborations at the Large Hadron Collider (LHC) have been hard at work characterising its properties and hunting down the diverse ways in which this ephemeral particle can decay. From the copious but experimentally challenging decay to b-quarks, to the exquisitely rare but low-background decay into four leptons, each offers a different avenue to study the properties of this new particle. Now, ATLAS has found first evidence of the Higgs boson decaying to two leptons (either an electron or a muon pair with opposite charge) and a photon. Known as “Dalitz decay”, this is one of the rarest Higgs boson decays yet seen at the LHC.

    For this analysis, ATLAS physicists targeted a Higgs boson decay mediated by a virtual photon. In contrast to the familiar stable, massless photon, this virtual particle typically has a very small (but non-zero) mass and decays instantly to two leptons.

    ATLAS physicists searched the full LHC Run 2 data set for collision events with a photon as well as two leptons whose combined mass was less than 30 GeV. In this region, decays with virtual photons should dominate over other processes that yield the same final state. ATLAS measured a Higgs boson signal rate in this decay channel that is 1.5 ± 0.5 times the expectation from the Standard Model. The chance that the observed signal was caused by a fluctuation in the background is 3.2 sigma – less than 1 in 1000.

    With vast amounts of data expected from the upcoming High-Luminosity LHC programme, studying rare Higgs boson decays will become the new norm. This will allow physicists to progress from reporting evidence for their existence, to confirming their observation and conducting detailed studies of Higgs boson properties – leading to ever more stringent tests of the Standard Model.

    Observing the Higgs boson decay to a photon and a lepton pair will make it possible for physicists to study charge parity (CP) symmetry. CP symmetry is a way of saying that the mirror image of interacting particles, where particles are replaced by their antiparticles, should look exactly the same as the original interaction. This was a natural assumption until 1964, when physicists studying kaon particles noticed – to their great surprise – that this is not the case in the particle physics world. Since then, physicists have learned that violation of CP symmetry is a signature of the electroweak interaction and have incorporated it into the Standard Model.

    But with the Higgs boson decaying into three particles, two of which are charged, physicists will be able to examine whether decays have a preferred direction – allowing researchers to improve their understanding of the origins of CP symmetry violation and perhaps even leading to hints for new physics beyond the Standard Model.

    Read more on the ATLAS and CERN Courier websites.

    https://home.cern/news/news/physics/atlas-finds-evidence-rare-higgs-boson-decay

    ( Feed URL: http://home.web.cern.ch/about/updates/feed )

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  • Karl Fogel at 2021-02-09T20:35:22Z

    Emacs geek Pleasure Of The Day for 9 Feb 2021:

    If you have the date string "20201209" from last December, and you are copying and pasting from that document to a similar document for this month, you can just do Ctrl-t (`transpose-chars') in the right place to get "20210209".

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  • Compelling evidence of neutrino process opens physics possibilities

    ParticleNews at 2021-01-26T18:28:49Z

    "Compelling evidence of neutrino process opens physics possibilities"

    Compelling evidence of neutrino process opens physics possibilitiesPress Releasexeno Tue, 01/26/2021 - 09:45421

    SCGSR Awardee Jacob Zettlemoyer

    SCGSR Awardee Jacob Zettlemoyer, Indiana University Bloomington, led data analysis and worked with ORNL’s Mike Febbraro on coatings, shown under blue light, to shift argon light to visible wavelengths to boost detection. Credit: Rex Tayloe/Indiana University

    The COHERENT particle physics experiment at the Department of Energy’s Oak Ridge National Laboratory has firmly established the existence of a new kind of neutrino interaction. Because neutrinos are electrically neutral and interact only weakly with matter, the quest to observe this interaction drove advances in detector technology and has added new information to theories aiming to explain mysteries of the cosmos.

    “The neutrino is thought to be at the heart of many open questions about the nature of the universe,” said Indiana University physics professor Rex Tayloe. He led the installation, operation and data analysis of a cryogenic liquid argon detector for neutrinos at the Spallation Neutron Source, or SNS, a DOE Office of Science User Facility at ORNL.

    The study, published in Physical Review Letters, observed that low-energy neutrinos interact with an argon nucleus through the weak nuclear force in a process called coherent elastic neutrino-nucleus scattering, or CEvNS, which is pronounced “sevens.” Like a ping-pong ball bombarding a softball, a neutrino that hits a nucleus transfers only a small amount of energy to the much larger nucleus, which recoils almost imperceptibly in response to the tiny assault.

    Laying the groundwork for the discovery made with the argon nucleus was a 2017 study  published in Science in which COHERENT collaborators used the world’s smallest neutrino detector to provide the first evidence of the CEvNS process as neutrinos interacted with larger and heavier cesium and iodide nuclei. Their recoils were even tinier, like bowling balls reacting to ping-pong balls.

    “The Standard Model of Particle Physics predicts coherent elastic scattering of neutrinos off nuclei,” said Duke University physicist Kate Scholberg, spokesperson and organizer of science and technology goals for COHERENT. The collaboration has 80 participants from 19 institutions and four countries. “Seeing the neutrino interaction with argon, the lightest nucleus for which it has been measured, confirms the earlier observation from heavier nuclei. Measuring the process precisely establishes constraints on alternative theoretical models.”

    Yuri Efremenko, a physicist at the University of Tennessee, Knoxville, and ORNL who led development of more sensitive photodetectors, said, “Argon provides a ‘door’ of sorts. The CEvNS process is like a building that we know should exist. The first measurement on sodium and iodide was one door that let us in to explore the building. We’ve now opened this other argon door.” The argon data is consistent with the Standard Model within error bars. However, increased precision enabled by bigger detectors may let scientists see something new. “Seeing something unexpected would be like opening the door and seeing fantastic treasures,” Efremenko added. 

    “We’re looking for ways to break the Standard Model. We love the Standard Model; it’s been really successful. But there are things it just doesn’t explain,” said physicist Jason Newby, ORNL’s lead for COHERENT. “We suspect that in these small places where the model might break down, answers to big questions about the nature of the universe, antimatter and dark matter, for instance, could lie in wait.”

    Maria del Valle Coello

    Indiana University physics undergraduate Maria del Valle Coello views the CENNS-10 detector installed in SNS’s Neutrino Alley. Credit: Rex Tayloe/Indiana University

    The COHERENT team uses the world’s brightest pulsed neutron source at SNS to help find the answers. The neutrons SNS produces for research create neutrinos as a byproduct. A service corridor beneath the SNS mercury target has been converted into a dedicated neutrino laboratory, dubbed Neutrino Alley, under the leadership of Newby and Efremenko. A 53-pound, or 24-kilogram, detector called CENNS-10 sits 90 feet, or 27.5 meters, from a low-energy neutrino source that optimizes opportunities to spot interactions that are coherent. This means approaching neutrinos see the weak force of the nucleus as a whole, leading to a bigger effect as compared to non-coherent interactions. 

    Bigger detectors are better at making high-precision measurements, and the CENNS-10 detector technology is easy to scale up by merely adding more liquid argon. 

    The CENNS-10 detector was originally built at Fermilab by COHERENT collaborator Jonghee Yoo. He and Tayloe brought it to IU and reworked it there before it was installed at SNS in 2016. Newby and Efremenko had prepared the SNS site with shielding of layered lead, copper and water to eliminate neutron backgrounds.

    After initial measurements indicated the experiment would not be dominated by background, wavelength-shifting coatings were applied to the photodetectors and inner reflectors that significantly improved light collection. The detector was calibrated by injecting krypton-83m into the liquid argon to allow calculation of the number of photons present.

    The published results used 18 months of data collected from CENNS-10. Analysis of the data revealed 159 CEvNS events, consistent with the Standard Model prediction. 

    The Spallation Neutron Source

    The Spallation Neutron Source also produces neutrinos in large quantities. Credit: Jason Richards/ORNL, U.S. Dept. of Energy

    COHERENT’s data will help researchers worldwide interpret their neutrino measurements and test their theories of possible new physics. The calculable fingerprint of neutrino–nucleus interactions predicted by the Standard Model and seen by COHERENT has practical applications, too. “This is a way to measure the distribution of neutrons inside nuclei and the density of neutron stars,” Efremenko said. “It’s a contribution to nuclear physics and astrophysics because the processes are very similar.”

    Different types of detectors are necessary for comprehensive neutrino studies. To further the goal of observing CEvNS on a variety of nuclei, a 16-kilogram detector based on germanium nuclei, which are bigger than argon but smaller than cesium and iodide, will be installed in Neutrino Alley next year. An array of sodium iodide detectors has been installed to augment the cesium iodide detector in operation there since 2017. 

    Meanwhile, data collection continues 24/7 despite COVID-19 because COHERENT collaborators monitor their liquid argon detector remotely. They aspire to enlarge it to ton-scale to see 25 times as many events annually and enable observation of detailed energy spectra that could reveal signatures of the new physics, including the existence of sterile neutrinos that have no weak interaction and, therefore, would not demonstrate a coherent interaction.

    Eventually, they would like to add an even bigger 10-ton, liquid-argon detector at SNS’s Second Target Station. “We’re pushing on the technology so that, in the future, we will be able to answer questions that require greater precision,” Newby said.

    The title of the Physical Review Letters paper is “First Detection of Coherent Elastic Neutrino-Nucleus Scattering on Argon.” 

    The DOE Office of Science Graduate Student Research (SCGSR) Program, Alfred P. Sloan Foundation, Consortium for Non-proliferation Enabling Capabilities, Korea’s Institute for Basic Science, U.S. National Science Foundation, and Russian Foundation for Basic Research supported the research. ORNL’s Laboratory Directed Research and Development Program funded local siting studies and installation to establish the experiment at the SNS. DOE’s Fermilab continues to loan the CENNS-10 detector. This research used resources of the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility at ORNL.

    UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

    Oak Ridge National Laboratory

    Aerial view of ORNL looking southwest

    Oak Ridge National Laboratory is the largest US Department of Energy science and energy laboratory, conducting basic and applied research to deliver transformative solutions to compelling problems in energy and security. ORNL’s diverse capabilities span a broad range of scientific and engineering disciplines, enabling the laboratory to explore fundamental science challenges and to carry out the research needed to accelerate the delivery of solutions to the marketplace in support of DOE’s national mission

    Oak Ridge National Laboratories
    1 Bethel Valley Rd
    Oak Ridge, TN37830
    United States

    865.576.1946

    https://www.ornl.gov

    Dawn Levy, Communications
    levyd@ornl.gov, 865.576.6448

    https://www.interactions.org/press-release/compelling-evidence-neutrino-process-opens-physics

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  • Snowmass summer study pushed to 2022

    ParticleNews at 2021-01-26T19:29:21Z

    "Snowmass summer study pushed to 2022"

    Organizers of the planning exercise that helps shape the future of US particle physics have moved its final workshop back by one year.

    Organizers have extended by one year the US particle physics community’s long-range planning process, originally scheduled for completion in fall 2021.

    For the past about 40 years, US particle physicists have gathered periodically to draw up their roadmap for the decade to come. Through this “Snowmass process,” physicists work to build consensus around a refined set of major scientific questions and ways to address them. A subgroup of the High Energy Physics Advisory Panel, which is appointed by the US Department of Energy and National Science Foundation, takes the community’s input from this process and pares it down into what’s called the P5 report. The funding agencies use this report to help guide their decisions about how to allocate their budgets.

    Leaders from the American Physical Society’s Division of Particles and Fields, who organize the Snowmass process, began preparing for its current iteration in fall 2019. They officially kicked things off at the society’s April 2020 meeting—the first major US physics meeting to move online due to the coronavirus pandemic. 

    Physicists adapted to pandemic-related restrictions, discussing Snowmass topics over online platforms such as Zoom and Slack. Despite new challenges, members of the physics community submitted an unexpectedly large number of letters of interest to the Snowmass topical groups: more than 1500. Participation in the first Snowmass community meeting of the process also exceeded expectations; around 3000 people participated in the virtual summit. 

    Now the physics community will adapt again, as they update the timeline for the Snowmass process. 

    “[B]ecause of the COVID-19 pandemic, the Snowmass Report will be delayed by one year and the overall schedule for the Snowmass process will be adjusted accordingly,” wrote DPF Past Chair Young-Kee Kim, who led the Snowmass process last year, in an email to Snowmass participants in December. 

    “We learned from DOE and NSF at the HEPAP meeting on December 3-4, 2020, that some important scientific milestones will arrive later than anticipated. For this reason, extending the timeline of the Snowmass and P5 process would enable our community’s scientific vision and the subsequent prioritization exercise, to be fully informed by the anticipated progress in our field as those milestones are met over the coming year.”

    Organizers gathered input from members of the US particle physics community and advisors from other regions around the world before making the change. 

    “This delay will allow a broader community (especially those who have been struggling in engaging in the Snowmass process due to circumstances related to coping with COVID-19) to participate more meaningfully in the Snowmass process,” Kim wrote.

    Snowmass organizers will share more details about the amended process by the end of the month.

    https://www.symmetrymagazine.org/article/snowmass-summer-study-pushed-to-2022?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

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  • Jason Self at 2021-01-24T05:34:38Z

    Here's my public safety announcement: Have you backed up today?

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    Like, out of your driveway? 🤪

    JanKusanagi at 2021-01-24T13:48:59Z