Stephen Sekula

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.

  • Astronomy Picture of the Day for 2018-05-19 12:30:01.558365

    Astronomy Picture of the Day (Unofficial) at 2018-05-19T17:30:02Z

    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.

    2018 May 19
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Reflections of Venus and Moon
    Image Credit & Copyright: Filippo Curti (Sanderphil Urban Observatory)

    Explanation: Posing near the western horizon, a brilliant evening star and slender young crescent shared reflections in a calm sea last Thursday after sunset. Recorded in this snapshot from the Atlantic beach at Santa Marinella near Rome, Italy, the lovely celestial conjunction of the two brightest beacons in the night sky could be enjoyed around the world. Seaside, light reflected by briefly horizontal surfaces of the gentle waves forms the shimmering columns across the water. Similar reflections by fluttering atmospheric ice crystals can create sometimes mysterious pillars of light. Of course, earthlight itself visibly illuminates the faint lunar night side.

    Tomorrow's picture: 30 Doradus

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  • George Standish at 2018-05-14T12:53:14Z

    Check out the Mockumentary video, it's priceless! 

    The guy in first shot has a lot of problems with his mic, but after that things improve.

    Also note "Few to no graduate students where harmed during filming".

    Just don't ask Dr. Sekula about the glove.

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  • JanKusanagi at 2018-05-13T22:42:52Z


    Such violence! xD

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  • Astronomy Picture of the Day for 2018-05-12 12:30:01.614010

    Astronomy Picture of the Day (Unofficial) at 2018-05-12T17:30:03Z

    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.

    2018 May 12
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    A Plurality of Singularities at the Galactic Center
    Image Credit: NASA/CXC / Columbia Univ./ C. Hailey et al.

    Explanation: A recent informal poll found that astronomers don't yet have a good collective noun for a group of black holes, but they need one. The red circles in this Chandra Observatory X-ray image identify a group of a dozen black holes that are members of binary star systems. With 5 to 30 times the mass of the Sun, the black hole binaries are swarming within about 3 light-years of the center of our galaxy where the supermassive black hole identified as Sagittarius A* (Sgr A*) resides. Yellow circles indicate X-ray sources that are likely less massive neutron stars or white dwarf stars in binary star systems. Alone, black holes would be invisible, but as part of a binary star system they accrete material from their normal companion star and generate X-rays. At the distance of the galactic center Chandra can detect only the brighter of these black hole binary systems as point-like sources of X-rays, hinting that many fainter X-ray emitting black hole binaries should exist there, as yet undetected.

    Tomorrow's picture: volcano with lightning

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  • dw at 2018-04-09T21:44:23Z

    Let's do a little experiment. It's obviously biased by my relative participation in each, but I'm comparing the reach of twitter, facebook, Diaspora, pump, G+, and GNU Social (plus anything that can talk directly to it...that is not via NavierStokes).

    Please like this if you see it. Obviously, if you want more people to like it, then you share it, but I'm only going to count likes.

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    Show all 6 replies
    It's a good point, that I did think of but haven't mentioned in any of the other posts. In order to be a true measure of reach we'd need to normalize for ability and desire to follow instructions in some sense. I noticed on twitter that the post was truncated and sending people to loadaverage, but I figured twitter would be lower than facebook anyway based on previous interactions.

    dw at 2018-04-10T11:41:32Z

    Facebook is up to 29. The slow burn...

    dw at 2018-04-23T13:39:35Z

    Diaspora is up to 17

    dw at 2018-04-29T01:19:58Z

  • Astronomy Picture of the Day for 2018-05-06 12:30:01.680790

    Astronomy Picture of the Day (Unofficial) at 2018-05-06T17:30:03Z

    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.

    2018 May 6
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Meteors, Planes, and a Galaxy over Bryce Canyon
    Image Credit & Copyright: Dave Lane

    Explanation: Sometimes land and sky are both busy and beautiful. The landscape pictured in the foreground encompasses Bryce Canyon in Utah, USA, famous for its many interesting rock structures eroded over millions of years. The featured skyscape, photogenic in its own right, encompasses the arching central disk of our Milky Way Galaxy, the short streaks of three passing planes near the horizon, at least four long streaks that are likely Eta Aquariid meteors, and many stars including the three bright stars that make up the Summer Triangle. The featured image is a digital panorama created from 12 smaller images during this date in 2014. Recurring every year, yesterday and tonight mark the peak of this year's Eta Aquriids meteor shower, where a patient observer with dark skies and dark-adapted eyes might expect to see a meteor every few minutes.

    Tomorrow's picture: unusually placed rock

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  • Construction Begins on One of the World’s Most Sensitive Dark Matter Experiments

    ParticleNews at 2018-05-07T13:28:43Z

    "Construction Begins on One of the World’s Most Sensitive Dark Matter Experiments"

    The SuperCDMS SNOLAB project, a multi-institutional effort led by SLAC, is expanding the hunt for dark matter to particles with properties not accessible to any other experiment.

    ( Feed URL: )

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  • Are you up for the TrackML challenge?

    ParticleNews at 2018-05-07T13:28:42Z

    "Are you up for the TrackML challenge?"

    10,000 tracks grouping 100,000 points in a future LHC detector as simulated for the TrackML challenge (Image: TrackML Challenge Team/CERN)

    Physicists from the ATLAS, CMS and LHCb collaborations have just launched the TrackML challenge – your chance to develop new machine-learning solutions for the next generation of particles detectors.

    The Large Hadron Collider (LHC) produces hundreds of millions of collisions every second, generating tens of petabytes of data a year. Handling this flood of data is a major challenge for the physicists, who have developed tools to process and filter the events online within a fraction of a second and select the most promising collision events.

    Managing the amount of data will become even more challenging in the near future: a major upgrade foreseen for 2026, the planned start of the High-Luminosity LHC, will increase the collision rate up to a factor of five. Innovative new software solutions will be needed to promptly reconstruct the tracks produced by these collisions with the available computing resources.

    To help address this issue, a team of machine-learning experts and LHC physicists has partnered with Kaggle to probe the question: can machine learning assist high-energy physics in discovering and characterising new particles?

    Specifically, in this competition, you’re challenged to build an algorithm that quickly and efficiently reconstructs particle tracks from 3D points left in the silicon detectors. The challenge consists of two phases:

    • The “Accuracy Phase” is now running on Kaggle from May to July 2018. Here the focus is on the highest score, irrespective of the evaluation time. This phase is an official IEEE WCCI competition (Rio de Janeiro, July 2018).

    • The “Throughput Phase” will run on Codalab from July to October 2018. Participants will submit their software to be evaluated by the platform. Incentive is on the throughput (or speed) of the evaluation while reaching a good score. This phase is an official NIPS competition (Montreal, December 2018).

    Sign up for the TrackML challenge today. The top three scorers will receive cash prizes. Selected winners may be awarded a top-notch NVIDIA v100 GPU, or get the chance to visit CERN or attend the 2018 Conference on Neural Information Processing Systems in Montreal (Canada).

    For more information and the participation conditions, visit the Kaggle challenge website and the official TrackML twitter account.

    ( Feed URL: )

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  • Splicer at 2018-05-05T20:25:59Z

    But I don't wanna learn python.

    Or does using it enough that I can cope with it when I have to while knowing that I prefer other tools when I have the choice count as "learning"?

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  • JanKusanagi at 2018-04-28T23:07:59Z

    🎉 🙌 🎉

    Live long and prosper, Hub!! 🖖

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  • Electrons and Positrons Collide for the first time in the SuperKEKB Accelerator

    ParticleNews at 2018-04-28T23:29:13Z

    "Electrons and Positrons Collide for the first time in the SuperKEKB Accelerator"

    Electrons and Positrons Collide for the first time in the SuperKEKB AcceleratorPress Releasexeno Thu, 04/26/2018 - 21:371218

    Electrons and positrons accelerated and stored by the SuperKEKB particle accelerator collided for the first time on 26 April 2018 0:38, UTC+09:00 at KEK in Tsukuba, Japan. The Belle II detector, installed at the collision point, recorded events from electron-positron annihilation (matter-antimatter annihilation) of the beam particles, which produced other particles likely including beauty quark and anti-beauty quark pairs as well as other hadronic and Bhabha scattering events1. These are the first electron-positron collisions at the KEK particle physics laboratory in 8 years; the previous KEKB particle collider ceased its operations in 2010.

    The Belle II detector at SuperKEKB was designed and built by an international collaboration of over 750 researchers from 25 countries and regions. Compared to Belle, the detector for the previous experiment, Belle II has dramatically improved capabilities and can detect and reconstruct events at much higher rates provided by the 40 times higher luminosity2 of SuperKEKB. A dataset of about 50 billion B anti-B meson pair production events, which is 50 times larger than the entire data sample of the KEKB/Belle project, will be accumulated in about 10 years of operation.

    SuperKEKB, along with the Belle II detector, is a facility designed to search for New Physics beyond the Standard Model by measuring rare decays of elementary particles such as beauty quarks, charm quarks, and tau leptons. Belle II will tackle the problem of finding evidence of the existence of new particles, a new possible reason why matter is dominant compared with antimatter and answer other open fundamental questions in understanding the universe.

    Last month, KEK began a new stage of operation of the SuperKEKB electron-positron collider, with a brand new positron damping ring, a new extremely complex system of superconducting final focusing magnets, and the Belle II detector in place at the interaction point. A beam of electrons was successfully stored for the first time in the main high energy ring on March 21st. A beam of positrons was also successfully stored in the main low energy ring on March 31st. Since then, final accelerator tuning of the two beams for collisions at the center of Belle II has continued for several weeks. 

    In contrast to the LHC at CERN in Geneva, Switzerland, which is the world’s highest energy proton accelerator, SuperKEKB/Belle II is designed to have the world’s highest luminosity. SuperKEKB is the leading accelerator on the “luminosity frontier”. Background information on the science goals of the SuperKEKB/Belle II facility is available on the Belle II public web page:

    Dr. Masanori Yamauchi  Director General of KEK

    “It is my great pleasure to announce the first collisions in the SuperKEKB accelerator and to celebrate the start of the Belle II Experiment after more than 7 years of major improvements. I am looking forward to seeing how the results from the Belle II Experiment help humankind understand the nature of the universe. We are grateful to everyone who has supported the project so far. Though there will be further difficulties that we must face before the SuperKEKB accelerator achieves its design luminosity, 40 times higher than KEKB’s world record, KEK will strive towards success in research together with many collaborators from all over the world.”

    Prof. Tom Browder  University of Hawaii, Belle II Spokesperson

    “After more than seven years of construction and preparation by many dedicated and talented researchers, engineers and students, the Belle II experiment has finally started. This is a truly gratifying moment for all of us in the international collaboration. We now look forward to launching the physics program of the first electron-positron super B Factory. The world is waiting for our results.”

    Dr. Carlos Marinas  University of Bonn, Belle II Deputy Run Coordinator and Pixel Detector Commissioning Leader

    “Detecting the first collisions is a great accomplishment of the teams involved in the beam commissioning process over the last months. The deep experience of the Japanese accelerator physicists has brought this far in a very short time and gave us confidence to gradually power up the Belle II detector without any significant risk to the experiment. Now it’s over to the detector physicists to make the best out of the discovery potential this superb machine is giving us; we are ready to accept the challenge.”

    Assistant Prof. Tomoyuki Konno  Kitasato University, Belle II DAQ Group

    “We have been working hard to upgrade the data acquisition system, consisting of thousands of electronics boards and computers, to handle a maximum trigger rate of 30 kilo-Hertz. Our centralized control system, which supervises all the electronics systems such as power supplies for sub-detectors, trigger timing distributions, readout electronics inside the detector and the high level trigger computing farm has been developed, commissioned and is now fully operational and ready to record the first collision data. We are happy to start data taking on time with beam collisions.”


    Bhabha scattering event; The electron-positron scattering process, which is named after the Indian physicist Homi J. Bhabha.

    Hadronic events; Hadron production processes caused by the collision of electrons and positrons. A hadron is a composite particle made of quarks held together by the strong force. Hadrons are categorized into two families: baryons, made of three quarks, and mesons, made of one quark and one antiquark. Pair production of a B meson and an anti-B meson is an example of a hadronic event.

    Luminosity is a measure of the rate or intensity of electron-positron collisions.

    Belle II detector with 7 detector subsystems


    Figure 2. A hadronic event in the Belle II detector. Heavier particles produced by the electron- positron collision decay to lighter particles.
    A hadronic event in the Belle II detector.


    Press Contacts in Japan

    Hikino Hajime, KEK PR Office:
    Prof. Toru Iijima, Belle II Outreach coordinator, Nagoya University:

    Additional images are available at the KEK webpage: KEK Image archive

    High Energy Accelerator Research Organization

    Render of International Linear Collider - Next-generation particle accelerator (Courtesy: Rey.Hori/KEK)

    KEK was established in 1997 in a reorganization of the Institute of Nuclear Study, University of Tokyo (established in 1955), the National Laboratory for High Energy Physics (established in 1971), and the Meson Science Laboratory of the University of Tokyo (established in 1988).

    Scientists at KEK use accelerators and perform research in high-energy physics to answer the most basic questions about the universe as a whole, and the matter and the life it contains.


    KEK, Japan
    1-1, Oho
    Tsukuba, Ibaraki

    + 81 029-879-6047 


    + 81 029-879-6049 (fax)

    Public Affairs
    Saeko Okada, Head of Communication

    ( Feed URL: )

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  • JanKusanagi at 2018-04-24T16:41:51Z

    Latest stable is 5.1.0, with 5.1.1 coming one of these days with a few small fixes and... Docker images, I think.

    5.2 (or was it 6.0?) coming "soonish" with partial ActivityPub support, probably.

    @AJ Jordan and @Evan Prodromou know more =)

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  • /var/log/universe.log

    at 2018-04-23T00:58:58Z

    I'm pretty sure @Stephen Sekula will enjoy this =)

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    That is awesome. I wish I had that log file in real life. 

    Stephen Sekula at 2018-04-23T02:08:51Z

  • ADMX announces breakthrough in axion dark matter detection technology

    ParticleNews at 2018-04-09T16:28:59Z

    "ADMX announces breakthrough in axion dark matter detection technology"

    ADMX announces breakthrough in axion dark matter detection technologyPress Releasexeno Mon, 04/09/2018 - 09:101018

    New result draws on 30 years of research and development and begins the definitive search for axion particles


    Forty years ago, scientists theorized a new kind of low-mass particle that could solve one of the enduring mysteries of nature: what dark matter is made of. Now a new chapter in the search for that particle has begun.


    This week, the Axion Dark Matter Experiment (ADMX) unveiled a new result (published in Physical Review Letters) that places it in a category of one: it is the world’s first and only experiment to have achieved the necessary sensitivity to “hear” the telltale signs of dark matter axions. This technological breakthrough is the result of more than 30 years of research and development, with the latest piece of the puzzle coming in the form of a quantum-enabled device that allows ADMX to listen for axions more closely than any experiment ever built.  


    ADMX is managed by the U.S. Department of Energy’s Fermi National Accelerator Laboratory and located at the University of Washington. This new result, the first from the second-generation run of ADMX, sets limits on a small range of frequencies where axions may be hiding, and sets the stage for a wider search in the coming years.


    “This result signals the start of the true hunt for axions,” said Fermilab’s Andrew Sonnenschein, the operations manager for ADMX. “If dark matter axions exist within the frequency band we will be probing for the next few years, then it’s only a matter of time before we find them.”


    One theory suggests that the dark matter that holds galaxies together might be made up of a vast number of low-mass particles, which are almost invisible to detection as they stream through the cosmos. Efforts in the 1980s to find this particle, named the axion by theorist Frank Wilczek, currently of the Massachusetts Institute of Technology, were unsuccessful, showing that their detection would be extremely challenging.


    ADMX is an axion haloscope — essentially a large, low-noise, radio receiver, which scientists tune to different frequencies and listen to find the axion signal frequency. Axions almost never interact with matter, but with the aid of a strong magnetic field and a cold, dark, properly tuned, reflective box, ADMX can “hear” photons created when axions convert into electromagnetic waves inside the detector.


    “If you think of an AM radio, it’s exactly like that,” said Gray Rybka, co-spokesperson for ADMX and assistant professor at the University of Washington. “We’ve built a radio that looks for a radio station, but we don't know its frequency. We turn the knob slowly while listening. Ideally we will hear a tone when the frequency is right.”


    This detection method, which might make the "invisible axion" visible, was invented by Pierre Sikivie of the University of Florida in 1983, as was the notion that galactic halos could be made of axions. Pioneering experiments and analyses by a collaboration of Fermilab, the University of Rochester and the U.S. Department of Energy’s Brookhaven National Laboratory, as well as scientists at the University of Florida, demonstrated the practicality of the experiment. This led to the construction in the late 1990s of a large-scale detector at the U.S. Department of Energy’s Lawrence Livermore National Laboratory that is the basis of the current ADMX.


    It was only recently, however, that the ADMX team has been able to deploy superconducting quantum amplifiers to their full potential enabling the experiment to reach unprecedented sensitivity. Previous runs of ADMX were stymied by background noise generated by thermal radiation and the machine’s own electronics.


    Fixing thermal radiation noise is easy: a refrigeration system cools the detector down to 0.1 Kelvin (roughly -460 degrees Fahrenheit). But eliminating the noise from electronics proved more difficult. The first runs of ADMX used standard transistor amplifiers, but after connecting with John Clarke, a professor at the University of California Berkeley, Clarke developed a quantum-limited amplifier for the experiment.  This much quieter technology, combined with the refrigeration unit, reduces the noise by a significant enough level that the signal, should ADMX discover one, will come through loud and clear.


    “The initial versions of this experiment, with transistor-based amplifiers would have taken hundreds of years to scan the most likely range of axion masses. With the new superconducting detectors we can search the same range on timescales of only a few years,” said Gianpaolo Carosi, co-spokesperson for ADMX and scientist at Lawrence Livermore National Laboratory.


    “This result plants a flag,” said Leslie Rosenberg, professor at the University of Washington and chief scientist for ADMX. “It tells the world that we have the sensitivity, and have a very good shot at finding the axion. No new technology is needed. We don’t need a miracle anymore, we just need the time.”


    ADMX will now test millions of frequencies at this level of sensitivity. If axions are found, it would be a major discovery that could explain not only dark matter, but other lingering mysteries of the universe. If ADMX does not find axions, that may force theorists to devise new solutions to those riddles.


    “A discovery could come at any time over the next few years,” said scientist Aaron Chou of Fermilab. “It’s been a long road getting to this point, but we’re about to begin the most exciting time in this ongoing search for axions.”


    Read the paper in Physical Review Letters


    This research is supported by the U.S. Department of Energy Office of Science, the Heising-Simons Foundation and research and development programs at the U.S. DOE’s Lawrence Livermore National Laboratory and the U.S. DOE’s Pacific Northwest National Laboratory.


    The ADMX collaboration includes scientists at Fermilab, the University of Washington, Lawrence Livermore National Laboratory, Pacific Northwest National Laboratory, Los Alamos National Laboratory, the National Radio Astronomy Observatory, the University of California at Berkeley, the University of Chicago, the University of Florida and the University of Sheffield.


    Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between the University of Chicago and the Universities Research Association Inc. Visit Fermilab’s website at and follow us on Twitter at @Fermilab.

    The University of Washington was founded in 1861 and is one of the pre-eminent public higher education and research institutions in the world. The UW has more than 100 members of the National Academies, elite programs in many fields, and annual standing since 1974 among the top five universities in receipt of federal research funding. Learn more at


    DOE’s 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, please visit


    The Heising-Simons Foundation is a family foundation based in Los Altos, California, enabling groundbreaking research in science, among other issues. For more information, please visit


    Media contacts:

    • Andre Salles, Fermilab Office of Communication,, 630-840-3351
    • James Urton, University of Washington,, 206-543-2580

    Science contacts:

    • Andrew Sonnenschein, Fermilab, ADMX operations manager,, 630-840-2883
    • Gray Rybka, University of Washington, ADMX co-spokesperson,, 206-543-2797

    Fermi National Accelerator Laboratory

    Fermilab from the air

    The Fermilab particle accelerator complex provides beam to numerous experiments and test stations. The accelerators can make beams of protons, neutrinos, muons, and other particles. The two-mile Main Injector makes the world's most intense high-energy neutrino beam. (Photographer: Reidar Hahn)

    Fermilab is America's particle physics and accelerator laboratory. Founded in 1967, Fermilab drives discovery by investigating the smallest building blocks of matter using world-leading particle accelerator and detector facilities. We also use the universe as a laboratory, making measurements of the cosmos to the mysteries of dark matter and dark energy. Fermilab is located near Chicago, Illinois, and is managed by Fermi Research Alliance, LLC for the U.S. Department of Energy Office of Science.

    What are we made of? How did the universe begin? What secrets do the smallest, most elemental particles of matter hold, and how can they help us understand the intricacies of space and time?

    Since 1967, Fermilab has worked to answer these and other fundamental questions and enhance our understanding of everything we see around us. As the United States' premier particle physics laboratory, we do science that matters. We work together with our international partners on the world's most advanced particle accelerators and dig down to the smallest building blocks of matter. We also probe the farthest reaches of the universe, seeking out the nature of dark matter and dark energy.

    Fermilab's 6,800-acre site is located in Batavia, Illinois, and is managed by the Fermi Research Alliance LLC for the U.S. Department of Energy Office of Science. FRA is a partnership of the University of Chicago and Universities Research Association Inc., a consortium of 89 research universities.

    P.O. Box 500
    Batavia, IL60510-0500
    United States

    + 1 630 840 3000


    + 1 630 840 4343 (fax)

    Andre Salles
    Fermilab Office of Communication
    + 1 630 840 3351
    + 1 630 840 8780 (fax)

    ( Feed URL: )

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  • Astronomy Picture of the Day for 2018-04-09 12:30:02.086911

    Astronomy Picture of the Day (Unofficial) at 2018-04-09T17:30:02Z

    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.

    2018 April 9

    The Sun Unleashed: Monster Filament in Ultraviolet
    Video Credit: NASA GSFC's Scientific Visualization Studio, Solar Dynamics Obs.

    Explanation: One of the most spectacular solar sights is an explosive flare. In 2011 June, the Sun unleashed somewhat impressive, medium-sized solar flare as rotation carried active regions of sunpots toward the solar limb. That flare, though, was followed by an astounding gush of magnetized plasma -- a monster filament seen erupting at the Sun's edge in this extreme ultraviolet image from NASA's Solar Dynamics Observatory. Featured here is a time-lapse video of that hours-long event showing darker, cooler plasma raining down across a broad area of the Sun's surface, arcing along otherwise invisible magnetic field lines. An associated coronal mass ejection, a massive cloud of high energy particles, was blasted in the general direction of the Earth,and made a glancing blow to Earth's magnetosphere.

    Tomorrow's picture: sky dragon

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  • JanKusanagi at 2018-04-11T02:50:25Z

    Hang in there, Mr. Kellat! =)

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  • JanKusanagi at 2018-04-08T16:33:41Z

    We know your full name now! =)

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  • Beams are back in the LHC

    ParticleNews at 2018-03-30T12:28:35Z

    "Beams are back in the LHC"

    View of the LHC in 2018, before the restart of the accelerato. (Image: Maximilien Brice, Julien Ordan/CERN)

    The Large Hadron Collider is back in business! On Friday 30 March, at 12:17 pm, protons circulated in the 27-km ring for the first time in 2018. The world’s most powerful particle accelerator thus entered its seventh year of data taking and its fourth year at 13 TeV collision energy.

    Restarting an accelerator involves much more than just flicking a switch, especially as the LHC is the final link in an accelerator chain comprising five separate machines. Following the winter break, which enabled teams to carry out a whole host of maintenance operations, the machine operators gradually have brought the infrastructures and accelerators back on line. At the beginning of March, the first protons were extracted from their hydrogen bottle and injected into the Linac2, and then into the PS Booster. On 8 March, it was the turn of the Proton Synchrotron (PS) to receive beams, and then, a week later, the Super Proton Synchrotron (SPS).

    Applause in the CERN Control Centre after the beam makes a first turn of the LHC loop. Sitting, the operators in charge of restarting the accelerator. Standing behind them, from left to right, Rende Steerenberg, Head of Operation, Frédérick Bordry, Director for Accelerators and Technology, Fabiola Gianotti, CERN Director-General, and Jörg Wenninger, in charge of LHC Operation. (Image: CERN)

    In parallel, the teams have been checking all the LHC hardware, such as the cryogenic cooling systems, the radiofrequency cavities (which accelerate the particles), the power supplies, the magnets, the vacuum system and the safety installations. For example, no fewer than 1 560 electrical circuits had to be powered and about 10 000 tests performed. Only once all these tests had been completed could particles be injected into the LHC.

    Even so, commissioning is far from over. The first beams circulating only have one bunch of particles, which contains 20 times fewer protons than in normal operation. And their energy is limited to the injection energy of 450 GeV. Further adjustments and tests will be needed over the coming days before the energy and the number of bunches in each beam can be increased and the bunches squeezed to produce first collisions. Physics operation should start in May.

    The operation objective for 2018 is to accumulate more data than in 2017: the target is 60 inverse femtobarns (fb-1) of integrated luminosity (against 50 fb-1 in 2017). Luminosity is a measurement of the number of potential collisions per surface unit in a given period of time.

    "LHC page 1" shows the status of the LHC on 30 March. The blue line on the right of the screen indicates the first beam circulating in the LHC in 2018. (Image: CERN)

    While we await collisions in the LHC, data taking is already starting elsewhere. CERN’s accelerators provide particles for a diverse array of experiments. The PS has already started supplying beams to the nuclear physics facility n_TOF and to the experiments in the East Hall. The nuclear physics programme at ISOLDE should start up on 9 April, while the Antiproton decelerator should start again in the second half of April.

    2018 is an important year for the collaborations using CERN’s accelerators, as it will be the last year of Run 2. In December, the accelerator complex will be shut down for two years of upgrade work aimed at improving performance further still and preparing for the High-Luminosity LHC.


    ( Feed URL: )

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  • The Jabber/XMPP Newsletter, 30 March 2018

    at 2018-03-30T20:53:45Z

    “Welcome to the second edition of our newsletter. ”

    XMPP rocks!! 🤘

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    » Aqeel Zafar:

    “Except no one uses it :-/”

    I use it. And if you don't use it because "no one uses it", you're not helping.

    JanKusanagi at 2018-03-31T20:21:59Z

  • #MozillaTurns20 @ #MozTW

    at 2018-03-31T03:41:08Z

    MozillaTurns20 event at MozTW. Photo by Irvin Chen (CC BY-NC 2.0).


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