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  • LS2 Report: 2000 kilometres of cable

    2019-06-26T08:28:19Z via NavierStokesApp To: Public

    "LS2 Report: 2000 kilometres of cable"

    LS2 Report: 2000 kilometres of cable

    anschaef Tue, 06/25/2019 - 10:10

    Some 40 000 cables will be installed or removed at CERN during LS2. Laid end to end, they would stretch for 2000 kilometres!

    The work involves two types of cable: copper cables, which transmit signals to the accelerator systems and supply the magnets, and fibre-optic cables, which transmit data in the form of light signals. The latter weave through all of CERN’s installations, from Meyrin to Prévessin, including the accelerator tunnels, experiments and technical halls, like an enormous spider’s web.

    “Optical fibres and copper cables transmit all the information collected or sent by the detectors, beam instrumentation, sensors, control panels, computing infrastructure, and so on,” explains Daniel Ricci, the leader of the section in charge of cabling (EN-EL-FC) within the EN department. “Our work covers all of CERN’s service networks: optical fibres and copper cables are everywhere.”,Civil Engineering and Infrastructure
    Water-cooled cables in the LHC tunnel. These cables carry the current (up to 13 000 amperes) from the power converters to the power supplies (Image: CERN)

    They are indeed, and in impressive quantities: for example, some 20 000 optical fibres contained within 220 cables lie at the heart of the ALICE experiment, and 1200 copper signal cables are being installed in the SPS in the framework of the Fire Safety project. The EN-EL-FC section is also contributing to other major CERN projects during LS2, including the LIU (LHC Injectors Upgrade), the renovation of the East Area, the renovation of the SPS access system, the commissioning of the ELENA extraction lines and the HL-LHC.

    “CERN is probably the only place in the world where several thousand kilometres of radiation-resistant optical fibre are needed,” says Daniel Ricci. “We maintain very close ties with industry, where our expertise is used to adapt and improve this type of fibre.”

    Of the 40 000 cables to be dealt with during LS2, 15 000 are obsolete copper cables that need to be removed. But first, they need to be identified. Since CERN was founded 65 years ago, some 450 000 cables have been installed, and many of them are still snaking through the nooks and crannies of the Laboratory. “Since LS1, we have been methodically going through all of CERN’s old paper cable databases, identifying each cable and listing it in our digital database,” explains Daniel Ricci. “Of the 95 000 cables to be retained, 50 000 have already been digitised.”,Civil Engineering and Infrastructure
    Many cables that are still needed for operations were pulled out of their cable trays in order to facilitate the removal of obsolete ones (here, in the SPS) (Image: CERN)

    CERN’s biggest ever cable removal campaign has been under way since 2016. During the most recent year-end technical stops (YETS and EYETS), the Booster and middle ring of the PS were relieved of their old, obsolete cables. Cable removal is currently under way at points 3 and 5 of the SPS.

    To complete this gargantuan task, the EN-EL-FC section, which usually comprises 20 people, has recruited some outside help. Sixteen extra people – fellows, project associates and members of other groups – are lending a hand during LS2. The contractors’ teams, which comprise several dozen technicians working on site, have also been reinforced in order to keep up with the breakneck pace of work during the long shutdown. “Coordination, planning and teamwork are indispensable if we are to successfully complete the 120 cabling and cable removal projects scheduled for LS2,” says Daniel Ricci. “We’re lucky to have a very versatile team who are able to advise clients on different types of cable, carry out technical studies, organise logistics and coordination between the various parties and supervise the worksites.”

    No fewer than 140 members of the CERN personnel and contractors’ personnel are working on the various LS2 cabling and cable removal projects, collaborating with the end users to ensure that quality control is as efficient as possible. “We would like to thank all the teams and users for their professionalism and their commitment. They are working to an extremely high standard while scrupulously respecting both deadlines and safety,” says Daniel Ricci.

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  • The future of particle accelerators may be autonomous

    2019-06-25T13:28:30Z via NavierStokesApp To: Public

    "The future of particle accelerators may be autonomous"

    Particle accelerators are some of the most complicated machines in science. Scientists are working on ways to run them with a diminishing amount of direction from humans.

    An illustration of robot hands typing on a computer

    In 2015, operators at the Linac Coherent Light Source particle accelerator looked into how they were spending their time managing the machine. They tracked the hours they spent on tasks like investigating problems and orchestrating new configurations of the particle beam for different experiments. 

    They discovered that, if they could automate the process of tuning the beam—tweaking the magnets that keep the LCLS particle beam on its course through the machine—it would free up a few hundred hours each year. 

    Scientists have been working to automate different aspects of the operation of accelerators since the 1980s. In today’s more autonomous era of self-driving cars and vacuuming robots, efforts are still going strong, and the next generation of particle accelerators promises to be more automated than ever. Scientists are using machine learning to optimize beamlines more efficiently, detect problems more effectively and create the simulations they need in real-time. 

    Quicker fixes

    With any machine, there is a chance that a part might malfunction or break. In the case of an accelerator, that part might be one of the many magnets that direct the particle beam.

    If one magnet stops working, there are ways to circumvent the problem using the magnets around it. But it’s not easy. A particle accelerator is a nonlinear system; when an operator makes a change to it, all of the possible downstream effects of that change can be difficult to predict. 

    “The human brain isn’t good at that kind of optimization,” says Dan Ratner, the leader of the strategic initiative for machine learning at the US Department of Energy’s SLAC National Accelerator Laboratory in California. 

    An operator can find the solution by trial and error, but that can take some time. With machine learning, an autonomous accelerator could potentially do the same task many times faster. 

    In December 2018, operators at LCLS at SLAC successfully tested an algorithm trained on simulations and actual data from the machine to tune the beam.

    Ratner doesn’t expect either LCLS or its upgrade, LCLS-II, scheduled to come online in 2021, to run without human operators, but he’s hoping to give operators a new tool. “Ultimately, we’re trying to free up operators for tasks that really need a human,” he says.

    Practical predictions

    At Fermi National Accelerator Laboratory in Illinois, physicist Jean-Paul Carneiro is working on an upgrade to the lab’s accelerator complex in the hopes that it will one day run with little to no human intervention.  

    He was recently awarded a two-year grant for the project through the University of Chicago’s FACCTS program—France And Chicago Collaborating in The Sciences. He is integrating a code developed by scientist Dider Uriot at France’s Saclay Nuclear Research Center into the lab’s PIP-II Injector Test (PIP2IT) facility. 

    PIP2IT is the proving ground for technologies intended for PIP-II, the upgrade to Fermilab’s accelerator complex that will supply the world’s most intense beams of neutrinos for the international Deep Underground Neutrino Experiment. 

    Carneiro says autonomous accelerator operation would increase the usability of the beam for experiments by drastically reducing the accelerator’s downtime. On average, accelerators can currently expect to run at about 90% usability, he says. “If you want to achieve a 98 or 99% availability, the only way to do it is with a computer code.” 

    Beyond quickly fixing tuning problems, another way to increase the availability of beam is to detect potential complications before they happen. 

    Even in relatively stable areas, the Earth is constantly shifting under our feet—and shifting underground particle accelerators as well. People don’t feel these movements, but an accelerator beam certainly does. Over the course of a few days, these shifts can cause the beam to begin creeping away from its intended course. An autonomous accelerator could correct the beam’s path before a human would even notice the problem. 

    Lia Merminga, PIP-II project director at Fermilab, says she thinks the joint project with CEA Saclay is a fantastic opportunity for the laboratory. “Part of our laboratory’s mission is to advance the science and technology of particle accelerators. These advancements will free up accelerator physicists to focus their talent more on developing new ideas and concepts, while providing users with higher reliability and more efficient beam delivery, ultimately increasing the scientific output.”

    Speedy simulations

    Accelerator operators don’t spend all of their time trouble-shooting; they also make changes to the beam to optimize it for specific experiments. Scientists can apply for time on an accelerator to conduct a study. The parameters they originally wanted sometimes change as they begin to conduct their experiment. Finding ways to automate this process would save operators and experimental physicists countless hours. 

    Auralee Edelen, a research associate at SLAC, is doing just that by exploring how scientists can improve their models of different beam configurations and how to best achieve them.

    To map the many parameters of an entire beam line from start to end, scientists have thus far needed to use thousands of hours on a supercomputer—not always ideal for online adjustments or finding the best way to obtain a particular beam configuration. A machine learning model, on the other hand, could be trained to simulate what would happen if variables were changed, in under a second.

    “This is one of the new capabilities of machine learning that we want to leverage,” Edelen says. “We’re just now getting to a point where we can integrate these models into the control system for operators to use.”

    In 2016 a neural network—a machine learning algorithm designed to recognize patterns—put this idea to the test at the Fermilab Accelerator Science and Technology facility. It completed what had been a 20-minute process to compare a few different simulations in under a millisecond. Edelen is expanding on her FAST research at LCLS, pushing the limits of what is currently possible. 

    Simulations also come in handy when it isn’t possible for a scientist to take a measurement they want, because doing so would interfere with the beam. To get around this, scientists can use an algorithm to correlate the measurement with others that don’t affect the beam and infer what the desired measurement would have shown.

    Initial studies at FAST demonstrated that a neural network could use this technique to predict meaurements. Now, SLAC’s Facility for Advanced Accelerator and Experimental Tests, or FACET, and its successor, FACET-II, are leading SLAC’s effort to refine this technique for the scientists that use their beam line.

    “It’s an exciting time,” says Merminga. “Any one of these improvements would help advance the field of accelerator physics. I am delighted that PIP2IT is being used to test new concepts in accelerator operation.”

    Who knows—within the next few decades, autonomous accelerators may seem as mundane as roaming robotic vacuums.

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  • Dutch and US students win 2019 CERN Beamline for Schools competition

    2019-06-24T14:28:30Z via NavierStokesApp To: Public

    "Dutch and US students win 2019 CERN Beamline for Schools competition"

    Dutch and US students win 2019 CERN Beamline for Schools competitionPress Releasexeno Mon, 06/24/2019 - 07:592619

    The 2019 CERN Beamline for Schools winners: (from left) Team from the West High School in Salt Lake City, USA (Image: Kara Budge) and team from the Praedinius Gymnasium in Groningen, Netherlands (Image: Martin Mug).

    The 2019 CERN Beamline for Schools winners: (from left) Team from the West High School in Salt Lake City, USA (Image: Kara Budge) and team from the Praedinius Gymnasium in Groningen, Netherlands (Image: Martin Mug).

    Geneva and Hamburg: Two teams of high-school students, one from the Praedinius Gymnasium in Groningen, Netherlands, and one from the West High School in Salt Lake City, USA, have won the 2019 Beamline for Schools competition (BL4S). In October, these teams will be invited to the DESY1 research centre in Hamburg, Germany, to carry out their proposed experiments together with scientists from CERN and DESY.

    Beamline for Schools is a unique international competition that is open to high-school students all over the world. The students are invited to submit a proposal for an experiment that uses a beamline. Beamlines deliver a stream of subatomic particles to any given set-up, making it possible to study a broad variety of properties and processes in various scientific disciplines. They are operated at laboratories such as CERN and DESY.

    Since Beamline for Schools was launched in 2014 almost 10,000 students from 84 countries have participated. This year, 178 teams from 49 countries worldwide submitted a proposal for the sixth edition of the competition.

    Due to the second Long Shutdown of CERN’s accelerators for maintenance and upgrade, there is currently no beam at CERN, which has opened up opportunities to explore partnerships with other laboratories, namely DESY.

    “It is a great honour for us to host the finals of this year’s Beamline for Schools competition at DESY,” said Helmut Dosch, Chairman of the DESY Board of Directors. “We are really looking forward to meeting the extraordinary students who made it through with their proposals and we wish them a successful and rewarding time at the lab. We at DESY are committed to fostering the next generation of scientists, which CERN’s Beamline for Schools project does brilliantly.”

     “We are all very excited to welcome this year’s winners to DESY. This is a new chapter in the history of this competition because, for the first time, we are taking the finals of the competition to another research laboratory. As always, the more then 60 voluntary experts from CERN and DESY evaluated all the proposals for their creativity, motivation, proposed methodology, feasibility and their overall ability to explore some of the concepts of modern particle physics” said Sarah Aretz, BL4S project manager.

    The two winning teams of 2019 will look at fundamental differences between matter and antimatter. When electrons at high energies collide with a target, such as a piece of graphite, some of their energy gets transferred into photons. These photons can, in turn, transform into other particles. Eventually, a shower of particles at lower energy will develop. The team “Particle Peers” from the Praedinius Gymnasium, Groningen, Netherlands has proposed to compare the properties of the particle showers originating from electrons with those created from positrons, the antimatter partner of the electron.

    "I couldn't stop smiling when I heard the news that we’d won. It's unbelievable that we’ll get the opportunity to conduct our experiment with amazing scientists and meet new students who are just as enthusiastic about physics as I am," said Frederiek de Bruine from the “Particle Peers” team.

    The “DESY Chain” team from the West High School, Salt Lake City, USA, focuses on the properties of scintillators in its proposal. These are materials that are used for particle detection. The students aim to study the performance of these scintillators and compare their sensitivity to electrons and positrons. This may lead to more efficient particle detectors for a wide range of applications.

    “I’m so excited by the prospect of working at DESY this autumn, it’s such a once-in-a-lifetime opportunity. I’m proud to be a part of the first USA team to win the BL4S competition, especially because it provides access to equipment and systems I would otherwise never have dreamt of even seeing,” said August Muller from the “DESY Chain” team.

    The shortlist consisted of 20 teams, ten of which received a special mention. This is the second time that a Dutch team has won the competition. Previous winners came from schools in the Netherlands, Greece, Italy (twice), South Africa, Poland, the United Kingdom, Canada, India and the Philippines.

    Beamline for Schools is an Education and Outreach project funded by the CERN & Society Foundation and supported by individual donors, foundations and companies. For 2019, the project is partially funded by the Wilhelm and Else Heraeus Foundation; additional contributions have been received from the Motorola Solutions Foundation, Amgen Switzerland AG and the Ernest Solvay Fund, which is managed by the King Baudouin Foundation.


    Shortlist drawn up by CERN and DESY experts:

    A Light in the Darkness (USA)

    Centaurus Warriors (USA)

    Cosmic Conquerors (Thailand)

    DESY Chain (USA)

    DESYners (USA)

    JT/High Pawns (Pakistan)

    Jubarte Team (Brazil)

    Leftover Leptons (India)

    Magic Doubly Magic Nuclei (Poland)

    My Little Positron(Australia)

    Particle peers (The Netherlands)

    Raiders of the Lost Quark (UAE)

    RAM FAM (Australia)

    Salvo Krevas (Malaysia)

    Team John Monash Science School (Australia)

    The Baryonic Six (Sweden)

    The Lumineers (Pakistan)

    The Weak Force (South Africa)

    Unstoppable SPAS (China)

    Young Researchers (Ukraine)


    Special Mentions:

    Antimatter Tracker (Argentina)

    Cherenkoviously Brilliant (UK)

    EthioCosmos (Ethiopia)

    Kics Team (Sudan)

    Kleine Wissenschaftler (Iran)

    Observers of the microcosm (Ukraine)

    Quantum Minds (Mexico)

    SolarBeam (Thailand)

    Team Pentaquark (Bangladesh)

    YKS_Young Kurdish Scientists (Iran)


    Further information

    Video from the team “Particle peers”, Praedinius Gymnasium in Groningen (, Netherlands:

    Video from the team “DESY Chain”, West High School in Salt Lake City  (, US:


    Beamline for School

    Beamline for Schools 2019 Edition

    The evaluation of the sixth Beamline for Schools competition finally starts

    Previous winners

    1. DESY is one of the world’s leading particle accelerator centres. Researchers use the large‐scale facilities at DESY to explore the microcosm in all its variety – ranging from the interaction of tiny elementary particles to the behaviour of innovative nanomaterials, the vital processes that take place between biomolecules and the great mysteries of the universe. The accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. DESY is a member of the Helmholtz Association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent).


    Joe Incandela, CERN spokesperson for Higgs Boson search update (Courtesy: Maximilien Brice, Laurent Egli)

    At CERN, the European Organization for Nuclear Research, physicists and engineers are probing the fundamental structure of the universe. They use the world's largest and most complex scientific instruments to study the basic constituents of matter – the fundamental particles. The particles are made to collide together at close to the speed of light. The process gives the physicists clues about how the particles interact, and provides insights into the fundamental laws of nature.

    Contact information
    European Organization for Nuclear Research
    CH-1211 Genève 23


    Organisation Européenne pour
    la Recherche Nucléaire
    F-01631 CERN Cedex
    + 41 22 76 761 11
    + 41 22 76 765 55 (fax)

    Press Office
    Arnaud Marsollier
    +41 22 767 34 32
    +41 22 767 21 41


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  • Week 23 at the Pole

    2019-06-21T20:28:13Z via NavierStokesApp To: Public

    "Week 23 at the Pole"

    A quiet week at the Pole—but that doesn’t mean that nothing happened. First of all, look at that sky! Lots of stars and swirling auroras, but also a bright rising moon make for a very picturesque setting.

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  • The why of puppy dog eyes, and measuring honesty on a global scale

    2019-06-20T19:28:21Z via NavierStokesApp To: Public

    "The why of puppy dog eyes, and measuring honesty on a global scale"

    How can you resist puppy dog eyes? This sweet, soulful look might very well have been bred into canines by their intended victims—humans. Online News Editor David Grimm talks with host Meagan Cantwell about a new study on the evolution of this endearing facial maneuver. David also talks about what diseased dog spines can tell us about early domestication—were these marks of hard work or a gentler old age for our doggy domestics? Also this week, host Sarah Crespi talks with Michel Marechal of the University of Zurich in Switzerland about honesty around the globe. By tracking about 17,000 wallets left at hotels, post offices, and banks, his team found that we humans are a lot more honest than either economic models or our own intuitions give us credit for. This week’s episode was edited by Podigy. Ads on the show: MagellanTV Listen to previous podcasts. About the Science Podcast [Image: Molly Marshall/Flickr; Music: Jeffrey Cook]

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  • SLAC sends off woven grids for LUX-ZEPLIN dark matter detector

    2019-06-20T18:28:24Z via NavierStokesApp To: Public

    "SLAC sends off woven grids for LUX-ZEPLIN dark matter detector"

    Four large meshes woven from 2 miles of metal wire will extract potential signs of dark matter particles.

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  • Sharing CERN’s expertise in big data with the biomedical community

    2019-06-20T08:28:38Z via NavierStokesApp To: Public

    "Sharing CERN’s expertise in big data with the biomedical community"

    Sharing CERN’s expertise in big data with the biomedical community

    achintya Thu, 06/20/2019 - 09:47
    A neurological cell simulation
    A neurological cell simulation carried out through the BioDynaMo project: (Image: CERN)

    On 6 and 7 June, CERN hosted a first-of-its-kind workshop on big data in medicine. It concluded a two-year pilot investigation into how CERN-developed IT technologies and techniques could be used to address challenges faced in biomedicine. The workshop’s main goal was to establish terms for broader future collaboration with the medical and healthcare research communities.

    In 2017, CERN adopted a specific knowledge-transfer strategy for medical applications with the aim of sharing knowledge and ideas of particle accelerators, detectors and computing with the medical and healthcare communities to identify relevant applications. Particle physics has pioneered large-scale, distributed, data-driven research models. Now that other scientific fields are collecting and processing ever more data, CERN technologies could help in facing the challenges with data infrastructures, computing technologies, and software applications.

    This workshop brought together leaders from a variety of fields related to the application of big-data technologies and techniques in biomedicine, including the World Health Organization, the European Commission and a number of leading universities. Topics included personalised medicine, digital health ecosystems, blockchain, data handling and more. Discussions also focused on emerging technologies, such as machine learning and artificial intelligence (AI), as well as the ethics of these technologies — particularly when used in a biomedical context.

    The discussions will serve as the basis for a white paper to be published later this year, setting out the main societal and economic challenges in medical research and healthcare systems, describing how collaborative platforms and big-data technologies can help addressing such challenges, and providing recommendations on how such multi-disciplinary efforts could be organised.

    To find out more about the workshop read more on the CERN openlab website, and visit the event page to view the presentations.

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  • A miniature camera for the Large Synoptic Survey Telescope will help test the observatory and take first images

    2019-06-19T20:28:25Z via NavierStokesApp To: Public

    "A miniature camera for the Large Synoptic Survey Telescope will help test the observatory and take first images"

    SLAC completed its work on ComCam, a commissioning device to be installed in Chile later this year.

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  • Le CERN invite le public à explorer le futur, à l’occasion de ses journées portes ouvertes

    2019-06-19T13:28:22Z via NavierStokesApp To: Public

    "Le CERN invite le public à explorer le futur, à l’occasion de ses journées portes ouvertes"

    CERN invites the public to explore the future at its Open Days melissa Wed, 06/19/2019 - 10:15

    Open Days 2019 logo
    Logo of the CERN Open Days 2019 (Image: CERN)

    On 14 and 15 September, CERN will open its scientific facilities to the public from 9 a.m. to 6 p.m. Under the banner “Explore the future with us”, everyone is invited to come along to the Open Days to live the CERN experience and meet the men and women working on the technologies and discoveries of today and tomorrow.

    As always during the Open Days, the underground experiments and machines will, exceptionally, be accessible to the public. The weekend will be an unmissable opportunity to discuss, explore and have fun with science. The laboratories, workshops and control rooms on the surface will also be open. From theatre performances to proton football and chats over coffee with physicists, the event has the perfect mix of ingredients to take visitors of all ages into the very heart of one of the largest physics laboratories in the world.

    Entrance to the nine visit sites will be free and open to everyone. There will be plenty for all age groups to enjoy, with physics shows, demonstrations by firefighters and worksite machinery operators, face-to-face encounters with the LHC robots and escape games on offer to keep the youngest visitors enthralled. The list of activities is available on the Open Days website.

    “Education and introducing younger generations to science are key to meeting the challenges of the future,” says CERN’s Director-General, Fabiola Gianotti. “The Open Days are an opportunity to spark new passions, but also to introduce experts and novices of all ages to our machines, the technologies we use and their applications in our daily lives.”

    The 2019 Open Days will take place during the second long shutdown of the Large Hadron Collider (LHC), providing a unique opportunity to discover the major upgrade work that is currently being carried out at CERN in preparation for the LHC restart in 2021. This work aims to improve the LHC’s performance and prepare for the arrival of the High-Luminosity LHC (HL-LHC), which is planned for 2026. During the Open Days, physicists, engineers and technicians will explain all the ins and outs of their work and help visitors to discover the future of particle physics.

    Some visit itineraries will carry age restrictions: the underground installations will be accessible only to people over 12 years of age. To ensure that as many people as possible have the chance to explore the underground installations, the number of underground visits per person will be limited to two each day.

    Registration will be open from 26 June onwards on the Open Days website. Visitors will also be able to access all the information they need to create their own itinerary and make the most of a unique and unforgettable experience. It is strongly recommended to register online in order to guarantee your place.

    The Route de l’Europe and part of the Route de Meyrin will be closed to traffic on both days: visitors are therefore strongly recommended to use public and sustainable transport. Additional buses and trams will run, and a free shuttle service will take visitors to and from the nine visit sites, which are spread out over a large area. Free car parks will be available for motorised vehicles and bicycles. All the necessary measures will be taken to ensure that visitors can enjoy their visit in complete safety. The event will be accessible to people with reduced mobility.

    To facilitate access, journalists wishing to participate in the event are invited to register in advance: .


    2019 trailer

    2013 Open Days images

    2008 Open Days images

    Open Days website

    Contact details:

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  • A day in the life of an accelerator designer

    2019-06-18T17:28:31Z via NavierStokesApp To: Public

    "A day in the life of an accelerator designer"

    Physicist Tor Raubenheimer explores the world by climbing rocks and designing particle accelerators.

    Tor Raubenheimer

    What do particle accelerators and craggy outcrops have in common? Both have Tor Raubenheimer trotting the globe. Thanks to both his work at the Department of Energy’s SLAC National Accelerator Laboratory and his passion for rock climbing, he has gotten to know people and places on several continents.

    “There are places around the world where I know a group of people and I can go and work and hang out,” says Raubhenheimer. “It’s neat.”

    Raubenheimer is an accelerator physicist — someone who designs, builds or operates particle accelerators. It’s a title that only a few thousand people lay claim to worldwide. Throughout his career, Raubenheimer has operated SLAC’s accelerators and designed new ones through international collaborations.

    He is also an avid rock climber. He makes frequent trips to a local climbing gym — three or four times a week, he says — and occasionally, much longer trips to climbing destinations. Just in the last few years, he has climbed in Australia, Sardinia and Thailand as well as at California favorites like Joshua Tree National Park. For Raubenheimer, rock climbing is a fun way to get to know people and places.

    “It’s having something in common, right?” Raubenheimer says. “Either accelerator physics or climbing. When you go to a different area, it makes merging into the culture there much easier.”

    Raubenheimer’s climbing pursuits also played a part in bringing him to SLAC. During his college years as a physics and computer science double major at Dartmouth College, he took a year off to ski and climb in Yosemite National Park and was captivated by Yosemite Valley. After college, when he had the opportunity to work as a programmer at SLAC, the proximity to Yosemite and other outdoor wonders attracted him to California.

    Working at SLAC opened Raubenheimer’s eyes to accelerator physics.

    “As an undergraduate, I had no idea that the field even existed,” he says. “I knew about high-energy and particle physics. I knew about lasers. I didn’t know that there was actually a field studying accelerators.”

    As a programmer at SLAC, he worked on software for the damping rings that helped narrow the particle beams emitted by the two-mile SLAC linear accelerator. Occasionally, he needed to go into the linear accelerator tunnel to check on a component or fix something. It’s this hands-on work, he says, that got him hooked.

    “The immediate satisfaction of being able to do something and see a result was great,” Raubenheimer says.

    He decided to go to graduate school in physics and got his PhD at Stanford, where he worked on a couple of other research projects before returning to accelerator physics. He worked on the linear collider at SLAC as well as researching problems that would need to be solved to build more advanced linear colliders. During his postdoc at SLAC, he started working on the Linac Coherent Light Source (LCLS) X-ray laser and brought his knowledge of linear colliders to the project. In the years since, while a scientist and professor at SLAC and Stanford, he has worked on designing accelerator facilities at SLAC and internationally.

    For the last few years, Raubenheimer has been working on the upgrade for LCLS, called LCLS-II. The upgraded LCLS-II will be able to shoot electron pulses and produce X-ray laser flashes up to one million times per second. LCLS-II will let scientists investigate microscopic phenomena in incredible detail and may ultimately lead to advances in storing energy and curing diseases.

    The multifaceted nature of accelerator physics makes it an interesting challenge. On top of theory and simulations, Raubenheimer says, “you have to worry about plumbing, and all the details of how you support things, and what metals go in radiofrequency fields and what don’t. So it’s a very broad field. It requires expertise and knowledge across a wide set of disciplines.”

    Many physics experiments involve either huge facilities and thousands of collaborators, like the Large Hadron Collider experiments, or smaller-scale equipment and a handful of researchers. For Raubenheimer, one of the draws of accelerator physics is working on large-scale projects in small teams, which lets him have his fingers in many pies.

    “You’ll do the theory, you’ll do the simulation studies, and then you can do the experiments,” Raubenheimer says. “I like having large facilities to play with, but with a small group of people, you can really be involved in all aspects of the physics.”

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  • Week 22 at the Pole

    2019-06-18T16:28:20Z via NavierStokesApp To: Public

    "Week 22 at the Pole"

    Since the moon was down last week, many winterovers—including IceCube’s—were outside braving the (extreme) cold, looking to catch some good shots of the Milky Way or the aurora australis, also known as the southern lights.

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  • Four decades of gluons

    2019-06-18T14:28:22Z via NavierStokesApp To: Public

    "Four decades of gluons"

    Four decades of gluons

    abelchio Tue, 06/18/2019 - 09:26
    A three-jet event detected by the TASSO detector.
    A three-jet event detected by the TASSO detector. (Image: CERN)

    Forty years ago, in 1979, experiments at the DESY laboratory in Germany provided the first direct proof of the existence of gluons – the carriers of the strong force that “glue” quarks into protons, neutrons and other particles known collectively as hadrons. This discovery was a milestone in the history of particle physics, as it helped establish the theory of the strong force, known as quantum chromodynamics.

    The results followed from an idea that struck theorist John Ellis while walking in CERN’s corridors in 1976. As Ellis recounts, he was walking over the bridge from the CERN cafeteria back to his office, turning the corner by the library, when it occurred to him that “the simplest experimental situation to search directly for the gluon would be through production via bremsstrahlung in electron–positron annihilation”. In this process, an electron and a positron (the electron’s antiparticle) would annihilate and would occasionally produce three “jets” of particles, one of which being generated by a gluon radiated by a quark–antiquark pair.

    Ellis and theorists Mary Gaillard and Graham Ross then went on to write a paper titled “Search for Gluons in e+-e– Annihilation” in which they described a calculation of the process and showed how the PETRA collider at DESY and the PEP collider at SLAC would be able to observe it. Ellis then visited DESY, gave a seminar about the idea and talked to experimentalists preparing to work at PETRA.

    A couple of years later, and following more papers by Ellis, Gaillard and other theorists, PETRA was being commissioned and getting into the energy range required to test this theory. Soon after, at the International Neutrino Conference in Bergen, Norway, on 18 June 1979, researchers presented a three-jet collision event that had just been detected by the TASSO experiment at PETRA.

    At the European Physical Society conference at CERN a couple of weeks later, the TASSO collaboration presented several three-jet events and results of analyses that showed that the gluon had been discovered. One month later, in August 1979, three other experiments at PETRA showed similar events that lent support to TASSO’s findings.

    Find out more about the discovery in DESY’s coverage of the 40-year anniversary, in Ellis’ account, and in this 2004 CERN Courier article.

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  • “Programma INFN per Docenti” ai Laboratori Nazionali del Gran Sasso: iscrizioni aperte fino al 30 giugno

    2019-06-18T14:28:21Z via NavierStokesApp To: Public

    "“Programma INFN per Docenti” ai Laboratori Nazionali del Gran Sasso: iscrizioni aperte fino al 30 giugno"

    Nella seconda metà di ottobre si terrà ai Laboratori Nazionali del Gran Sasso un corso residenziale della durata di 5 giorni dedicato ai docenti della scuola media di secondo grado di materie scientifiche.

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  • ATLAS homes in on magnetic monopoles

    2019-06-14T09:28:27Z via NavierStokesApp To: Public

    "ATLAS homes in on magnetic monopoles"

    ATLAS homes in on magnetic monopoles

    abelchio Fri, 06/14/2019 - 11:00
    Magnetic monopoles and dipoles
    Conventional bar magnets are also called ‘magnetic dipoles’ because they have two magnetic poles (a “North” and a “South” magnetic pole, like the Earth). In theory, “magnetic monopoles” could exist that act like an isolated “magnetic charge”, i.e. either a “North” or a “South” magnetic pole. (Image: CERN)

    Break a magnet in two, no matter how small, and you’ll get two magnets each with a south and a north pole of opposite magnetic nature. However, some theories predict particles with an isolated magnetic pole, which would carry a magnetic charge analogous to a positive or negative electric charge. But despite many searches, such magnetic monopoles have never been spotted at particle colliders. A new search by the ATLAS collaboration at CERN places some of the tightest bounds yet on the production rate of these hypothetical particles. These results are complementary to those from CERN’s MoEDAL experiment, which is specifically designed to search for magnetic monopoles.

    Originally proposed in 1931 by physicist Paul Dirac, magnetic monopoles have since been shown to be an outcome of so-called grand unified theories (GUTs) of particle physics, which connect fundamental forces at high energies into a single force. Such GUT monopoles typically have masses that are too high for them to be spotted at particle colliders, but some extensions of the Standard Model predict monopoles with masses that could be in a range accessible to colliders.

    The latest ATLAS search is based on data from proton–proton collisions produced at the Large Hadron Collider at an energy of 13 TeV. The collaboration looked for signs in the data of large energy deposits that would be left behind by the magnetic monopoles in the ATLAS particle detector. The energy deposits would be proportional to their magnetic charge squared. Such large deposits are also an expected signature of high-electric-charge objects (HECOs), which may include mini black holes, so the search was also sensitive to HECOs.

    The team found no sign of magnetic monopoles or HECOs in the data but improved previous work on several fronts. Firstly, the search achieves improved limits on the production rate of monopoles that carry one or two units of a fundamental magnetic charge called Dirac charge. The new limits surpass those from MoEDAL, although MoEDAL is sensitive to a larger range of magnetic charge – up to five Dirac charges – and can probe monopoles produced by two mechanisms, whereas ATLAS probed only one. MoEDAL researchers are also working towards pushing the experiment to probe monopoles with magnetic charges well beyond five Dirac charges.

    In addition, the ATLAS search improves limits on the production of HECOs with electric charge between 20 and 60 times the charge of the electron. Finally, the search is the first to probe HECOs with charges greater than 60 times the electron charge, surpassing the charge probed by previous searches by ATLAS and also by the CMS collaboration.

    For more information about these results, see the ATLAS website.

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  • Better hurricane forecasts and spotting salts on Jupiter’s moon Europa

    2019-06-13T19:28:16Z via NavierStokesApp To: Public

    "Better hurricane forecasts and spotting salts on Jupiter’s moon Europa"

    We’ve all seen images or animations of hurricanes that color code the wind speeds inside the whirling mass—but it turns out we can do a better job measuring these winds and, as a result, better predict the path of the storm. Staff Writer Paul Voosen talks with host Sarah Crespi about how a microsatellite-based project for measuring hurricane wind speeds is showing signs of success—despite unexpected obstacles from the U.S. military’s tweaking of GPS signals.    Also this week, Sarah talks with graduate student Samantha Trumbo, a Ph.D. candidate in planetary science at the California Institute of Technology in Pasadena, about spotting chloride salts on the surface of Jupiter’s moon Europa. What can these salts on the surface tell us about the oceans that lie beneath Europa’s icy crust? This week’s episode was edited by Podigy. Ads on the show:; MagellanTV Listen to previous podcasts. About the Science Podcast [Image: Image Credit: NASA/JPL-Caltech/SETI Institute; Music: Jeffrey Cook]

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  • Laser trick produces high-energy terahertz pulses

    2019-06-13T17:28:16Z via NavierStokesApp To: Public

    "Laser trick produces high-energy terahertz pulses"

    Laser trick produces high-energy terahertz pulsesPress Releasexeno Thu, 06/13/2019 - 10:592519

    Milestone for compact particle accelerators

    concept art of dual laser pulses passing through a crystal and expanding into color gradients

    From the colour difference of two slightly delayed laser flashes (left) a non-linear crystal generates an energetic terahertz pulse (right). Credit: DESY, Lucid Berlin

    A team of scientists from DESY and the University of Hamburg has achieved an important milestone in the quest for a new type of compact particle accelerator. Using ultra-powerful pulses of laser light, they were able to produce particularly high-energy flashes of radiation in the terahertz range having a sharply defined wavelength (colour). Terahertz radiation is to open the way for a new generation of compact particle accelerators that will find room on a lab bench. The team headed by Andreas Maier and Franz Kärtner from the Hamburg Center for Free-Electron Laser Science (CFEL) is presenting its findings in the journal Nature Communications. CFEL is jointly run by DESY, the University of Hamburg and the Max Planck Society.

    The terahertz range of electromagnetic radiation lies between the infrared and microwave frequencies. Air travellers may be familiar with terahertz radiation from the full-body scanners used by airport security to search for objects hidden beneath a person’s garments. However, radiation in this frequency range might also be used to build compact particle accelerators.

    “The wavelength of terahertz radiation is about a thousand times shorter than the radio waves that are currently used to accelerate particles,” says Kärtner, who is a lead scientist at DESY. “This means that the components of the accelerator can also be built to be around a thousand times smaller.”

    The generation of high-energy terahertz pulses is therefore also an important step for the AXSIS (frontiers in Attosecond X-ray Science: Imaging and Spectroscopy) project at CFEL, funded by the European Research Council (ERC), which aims to open up completely new applications with compact terahertz particle accelerators.

    However, chivvying along an appreciable number of particles calls for powerful pulses of terahertz radiation having a sharply defined wavelength. This is precisely what the team has now managed to create.

    “In order to generate terahertz pulses, we fire two powerful pulses of laser light into a so-called non-linear crystal, with a minimal time delay between the two,” explains Maier from the University of Hamburg. The two laser pulses have a kind of colour gradient, meaning that the colour at the front of the pulse is different from that at the back. The slight time shift between the two pulses therefore leads to a slight difference in colour. “This difference lies precisely in the terahertz range,” says Maier. “The crystal converts the difference in colour into a terahertz pulse.”

    The method requires the two laser pulses to be precisely synchronised. The scientists achieve this by splitting a single pulse into two parts and sending one of them on a short detour so that it is slightly delayed before the two pulses are eventually superimposed again. However, the colour gradient along the pulses is not constant, in other words the colour does not change uniformly along the length of the pulse. Instead, the colour changes slowly at first, and then more and more quickly, producing a curved outline. As a result, the colour difference between the two staggered pulses is not constant. The difference is only appropriate for producing terahertz radiation over a narrow stretch of the pulse.

    “That was a big obstacle towards creating high-energy terahertz pulses,” as Maier reports. “Because straightening the colour gradient of the pulses, which would have been the obvious solution, is not easy to do in practice.”

    It was co-author Nicholas Matlis who came up with the crucial idea: he suggested that the colour profile of just one of the two partial pulses should be stretched slightly along the time axis. While this still does not alter the degree with which the colour changes along the pulse, the colour difference with respect to the other partial pulse now remains constant at all times.

    “The changes that need to be made to one of the pulses are minimal and surprisingly easy to achieve: all that was necessary was to insert a short length of a special glass into the beam,” reports Maier. “All of a sudden, the terahertz signal became stronger by a factor of 13.”

    In addition, the scientists used a particularly large non-linear crystal to produce the terahertz radiation, specially made for them by the Japanese Institute for Molecular Science in Okazaki.

    “By combining these two measures, we were able to produce terahertz pulses with an energy of 0.6 millijoules, which is a record for this technique and more than ten times higher than any terahertz pulse of sharply defined wavelength that has previously been generated by optical means,” says Kärtner. “Our work demonstrates that it is possible to produce sufficiently powerful terahertz pulses with sharply defined wavelengths in order to operate compact particle accelerators.”


    Spectral Phase Control of Interfering Chirped Pulses for High-Energy Narrowband Terahertz Generation; Spencer W. Jolly, Nicholas H. Matlis, Frederike Ahr, Vincent Leroux, Timo Eichner, Anne-Laure Calendron, Hideki Ishizuki, Takunori Taira, Franz X. Kärtner, and Andreas R. Maier; „Nature Communications“, 2019; DOI: 10.1038/s41467-019-10657-4

    DESY is one of the world’s leading particle accelerator centres. Researchers use the large‐scale facilities at DESY to explore the microcosm in all its variety – ranging from the interaction of tiny elementary particles to the behaviour of innovative nanomaterials and the vital processes that take place between biomolecules to the great mysteries of the universe. The accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. DESY is a member of the Helmholtz Association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent).


    Science contact

    Dr. Andreas R. Maier
    University of Hamburg
    +49 40 8998-6687

    Prof. Franz X. Kärtner
    +49 40 8998-6350

    Media contact

    Dr. Thomas Zoufal
    DESY press officer
    Phone: +49 40 8998-1666

    Deutsches Elektronen-Synchrotron

    The HERA accelerator at DESY in Hamburg was unique in that it smashed two totally different kinds of particles into each other – protons and electrons or positrons. HERA thus consists of two different accelerator rings: a superconducting proton ring and a normal-conducting electron ring. HERA ran from 1990 to 2007.

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

    DESY Hamburg
    Notkestraße 85

    + 49 40/8998-0

    PR Office
    Christian Mrotzek
    +49 40 8998-1665
    + 49 040 8998 4307 (fax)

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  • The proton, a century on

    2019-06-13T13:28:14Z via NavierStokesApp To: Public

    "The proton, a century on"

    The proton, a century on abelchio Thu, 06/13/2019 - 10:11

    It is 100 years since Ernest Rutherford published his results proving the existence of the proton. For decades, the proton was considered an elementary particle. But ever since researchers at the SLAC and DESY laboratories began firing electrons into protons, beginning in the 1960s, experiments have revealed that the proton has a complex internal structure, one that depends on how you look at it, or rather on how hard you hit it. A century on, however, much remains to be learnt about the proton. Check out the latest edition of the CERN Courier and read in-depth articles about what we know and don’t know about the proton.

    In “Rutherford, transmutation and the proton”, you’ll find an account of the historical events leading to Ernest Rutherford’s discovery of the proton, published in 1919. In “The proton laid bare”, you can read about scientists’ evolving knowledge of the proton, how a deeper understanding may be key to the search for new physics phenomena, and what remains to be learnt – including the origin of the proton’s spin, whether or not the proton decays on long timescales, and the puzzling, although soon-to-be resolved, value of its radius.

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  • The language of physics

    2019-06-11T20:28:12Z via NavierStokesApp To: Public

    "The language of physics"

    10 more words that mean something different to scientists.

    Physics Slang

    Word fans, rejoice! Symmetry is back with another list of 10 common words that take on a new meaning when spoken by scientists. Check out the first and second lists, then take these physics words for a spin, too:

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    A person talking about how uncertain they are might seem less than confident, but for scientists, it can be quite the opposite. Providing the measure of uncertainty gives context to how well something is known. Every measurement has some degree of error, and there’s natural variability to experimental results even without human intervention. It’s only after scientists establish the uncertainties in a mathematical way that they can see how a result compares to a numerical prediction or a previous measurement.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    The word “signal” might make you think of a gesture or preparing to make a turn in a car. In physics, a signal is the data coming from an expected source—the process or event that scientists are trying to capture. Experiments looking for rare, faint signals (such as the decay of a single proton or the minuscule deposit of energy from a dark matter particle) take great pains to understand, reduce or eliminate anything that could provide a false signal.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    You probably don’t want a bunch of noise when you’re trying to hear a particular sound—and physicists don’t want a bunch of noise when they are searching for a particular signal. Noise is the unwanted data that can be captured along with—and sometimes obscure—the signal a scientist is looking for. This distracting background can come from things like fluctuations in electronics or processes near an experiment such as everyday radioactive decay of materials or collisions of cosmic rays with the atmosphere. For experiments to work, the signal has to rise above the noise so that scientists can detect it.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    Not to be confused with making something wet, damping in physics is associated with reducing vibrations or oscillations. This is particularly important in particle accelerators, where bunches of particles, like boats on a lake, can leave wakes behind them. These wakes make passage trickier for the next bunch of particles. Using mechanical dampers can reduce the wake and improve how well an accelerator performs.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    It’s easy to imagine a spinning planet, ballerina or top. Physicists also use the term “spin,” but in a different way: to describe the properties of particles. In particular, physicists discovered that, at the quantum mechanical level, particles have an intrinsic property that is like a permanent rotation, even when a particle has zero diameter and is considered a point-like object that can’t be described as rotating. Thus spin is used to describe an effect, not the way that effect is actually generated.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    It’s not a steel girder or a toothy smile—a beam is a focused stream of particles. Beams are created by particle accelerators and can be made of different kinds of particles, such as protons, electrons, neutrons, ions or neutrinos. These concentrated torrents of particles can be manipulated, studied in physics experiments or crashed into targets to create other kinds of particles.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    For physicists, tunneling isn’t about the habits of moles or carving away mountains to make room for roads. Quantum tunneling is instead a phenomenon in which a particle can pass through a barrier it normally wouldn’t be able to cross. It’s a result of quantum mechanics, the strange way that things can act differently at the smallest scales than they do at the larger scales that we’re used to. Quantum tunneling occurs, for example, during radioactive decay when a particle escapes the nucleus of an atom.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    You might think of luminosity as how much light something emits. In astrophysics, this is pretty close: Luminosity is how much energy a celestial object like a star emits in a certain amount of time. But luminosity is also a term in collider physics, where it describes how many particles will pass through a certain point—say, the heart of a detector where the particle collisions happen. Higher luminosity means more particle collisions and a higher chance for making discoveries.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    “Quintessence” refers to a perfect example or the essence of something. But you also can find it in physics papers about the expansion of the universe. Dark energy is the mysterious force thought to be driving the expansion of our universe, defying the pull of gravity at an ever-growing rate. Scientists use the term quintessence to discuss the theoretical idea of an evolving type of dark energy that would change strength over time.

    Illustration by Sandbox Studio, Chicago with Corinne Mucha


    To us humans, a lifetime is—if we’re lucky—about 90 years. For particles, it’s another story. The lifetime of a particle is based on how long it takes to decay, or transform into other (typically lighter) particles. Those that decay quickly have lifetimes of slivers of a second. Higgs bosons, for example, only can expect to hang around for about 1.6 x 10-22 seconds. Other particles, such as protons, are incredibly long-lived. It’s unknown whether protons decay at all. If they do, they have a lifetime that is longer than the entire history of our universe so far. But that doesn’t mean that all protons necessarily live that long. Experiments could record evidence for the decay of a single proton on any day, revolutionizing our understanding of the building blocks of matter.

    A poster that includes all of the words from the article
    Artwork by Sandbox Studio, Chicago with Corinne Mucha

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  • Firmato accordo quadro tra l'INFN e la Sudcoreana IBS

    2019-06-11T09:28:09Z via NavierStokesApp To: Public

    "Firmato accordo quadro tra l'INFN e la Sudcoreana IBS"

    Sinergia sulle tecnologie e formazione delle nuove generazioni di fisici sono i temi al centro del recente accordo quadro sottoscritto tra l’INFN e l’istituto sudcoreano IBS Institute for Basic Science.

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  • Berkeley leans into search for light dark matter

    2019-06-10T19:28:08Z via NavierStokesApp To: Public

    "Berkeley leans into search for light dark matter"

    Dark matter could be much lower in mass and slighter in energy than previously thought.

    Photograph of hands in light blue rubber gloves holding detector components

    The search for dark matter is expanding. And going small.

    While dark matter abounds in the universe—it is by far the most common form of matter, making up about 85% of the universe’s total—it also hides in plain sight. We don’t yet know what it’s made of, though we can witness its gravitational pull on known matter.

    Theorized weakly interacting massive particles, or WIMPs, have been among the cast of likely suspects that could comprise dark matter, but they haven’t yet shown up where scientists had expected them.

    Casting many small nets

    So scientists are now redoubling their efforts by designing new and nimble experiments that can look for dark matter in previously unexplored ranges of particle mass and energy, using previously untested methods. The new approach, rather than relying on a few large experiments’ “nets” to try to snare one type of dark matter, is akin to casting many smaller nets with much finer mesh.

    Dark matter could be much “lighter,” or lower in mass and slighter in energy, than previously thought. It could be composed of theoretical, wavelike ultralight particles known as axions. It could be populated by a wild kingdom filled with many species of as-yet-undiscovered particles. And it may not be composed of particles at all.

    Momentum has been building for low-mass dark matter experiments, which could expand our current understanding of the makeup of matter as embodied in the Standard Model of particle physics, says Kathryn Zurek, a senior scientist and theoretical physicist at the US Department of Energy’s Lawrence Berkeley National Laboratory.

    Zurek, who is also affiliated with UC Berkeley, has been a pioneer in proposing low-mass dark matter theories and possible ways to detect it.

    “What experimental evidence do we have for physics beyond the Standard Model? Dark matter is one of the best ones,” she says. “There are these theoretical ideas that have been around for a decade or so,” and new developments in technology—such as new advances in quantum sensors and detector materials—have also helped to drive the impetus for new experiments.

    “The field has matured and blossomed over the last decade. It’s become mainstream—this is no longer the fringe,” she says. Low-mass dark matter discussions have moved from small conferences and workshops to a component of the overall strategy in searching for dark matter.

    Berkeley Lab and UC Berkeley, with their particular expertise in dark matter theories, experiments and cutting-edge detector and target R&D, are poised to make a big impact in this emerging area of the hunt for dark matter, she says.

    The need to search for “light” dark matter 

    Dark matter-related research by Zurek and other Berkeley Lab researchers is highlighted in a DOE report, “Basic Research Needs for Dark Matter Small Projects New Initiatives,” based on an October 2018 high-energy physics workshop on dark matter. Zurek and Dan McKinsey, a Berkeley Lab faculty senior scientist and UC Berkeley physics professor, served as co-leads on a workshop panel focused on dark matter direct-detection techniques, and this panel contributed to the report.

    The report proposes a focus on small-scale experiments—with project costs ranging from $2 million to $15 million—to search for dark matter particles that have a mass smaller than a proton. 

    This new, lower-mass search effort will have “the overarching goal of finally understanding the nature of the dark matter of the universe,” the report states.

    In a related effort, DOE this year solicited proposals for new dark matter experiments, with a May 30 deadline, and Berkeley Lab participated in the proposal process, McKinsey says.

    Berkeley is “a dark-matter mecca” that is primed for participating in this expanded search, he says. McKinsey has been a participant in large direct-detection dark matter experiments, including LUX and LUX-ZEPLIN, and is also working on low-mass dark matter detection techniques.

    Priorities in the expanded search

    The report highlights three major priority research directions in searching for low-mass dark matter that “are needed to achieve broad sensitivity and … to reach different key milestones”:

    1. Create and detect dark matter particles below the proton mass and associated forces, leveraging DOE accelerators that produce beams of energetic particles. Such experiments could potentially help us understand the origins of dark matter and explore its interactions with ordinary matter, the report states.
    2. Detect individual galactic dark matter particles—down to a mass measuring about 1 trillion times smaller than that of a proton—through interactions with advanced, ultrasensitive detectors. The report notes that there are already underground experimental areas and equipment that could be used in support of these new experiments.
    3. Detect galactic dark matter waves using advanced, ultrasensitive detectors with emphasis on the so-called QCD (quantum chromodynamics) axion. Advances in theory and technology now allow scientists to probe for the existence of this type of axion-based dark matter across the entire spectrum of its expected ultralight mass range, providing “a glimpse into the earliest moments in the origin of the universe and the laws of nature at ultrahigh energies and temperatures,” the report states.

    This axion, if it exists, could also help to explain properties associated with the universe’s strong force, which is responsible for holding most matter together—it binds particles together in an atom’s nucleus, for example.

    Searches for the traditional WIMP form of dark matter have increased in sensitivity about 1000-fold in the past decade.

    Prototype experiments at Berkeley

    Berkeley Lab and UC Berkeley researchers will at first focus on liquid helium and gallium arsenide crystals in searching for low-mass dark matter particle interactions in prototype laboratory experiments now in development at UC Berkeley.

    “Materials development is also part of the story, and also thinking about different types of excitations” in detector materials, Zurek says.

    Besides liquid helium and gallium arsenide, the materials that could be used to detect dark matter particles are diverse, “and the structures in them are going to allow you to couple to different dark matter candidates,” she says. “I think target diversity is extremely important.”

    The goal of these experiments, which are expected to begin within the next few months, is to develop the technology and techniques so that they can be scaled up for deep-underground experiments at other sites that will provide additional shielding from the natural shower of particle “noise” raining down from the sun and other sources.

    McKinsey, who is working on the prototype experiments at UC Berkeley, says that the liquid helium experiment there will seek out any signs of dark matter particles causing nuclear recoil—a process through which a particle interaction gives the nucleus of an atom a slight jolt that researchers hope can be amplified and detected.

    One of the experiments seeks to measure excitations from dark matter interactions that lead to the measurable evaporation of a single helium atom.

    “If a dark matter particle scatters (on liquid helium), you get a blob of excitation,” McKinsey says. “You could get millions of excitations on the surface—you get a big heat signal.”

    He notes that atoms in liquid helium and crystals of gallium arsenide have properties that allow them to light up or “scintillate” in particle interactions. Researchers will at first use more conventional light detectors, known as photomultiplier tubes, and then move to more sensitive, next-generation detectors.

    “Basically, over the next year we will be studying light signals and heat signals,” McKinsey says. “The ratio of heat to light will give us an idea what each event is.”

    These early investigations will determine whether the tested techniques can be effective in low-mass dark matter detection at other sites that provide a lower-noise environment. “We think this will allow us to probe much lower energy thresholds,” he says.

    New ideas enabled by new technology

    The report also notes a wide variety of other approaches to the search for low-mass dark matter.

    “There are tons of different, cool technologies out there” even beyond those covered in the report that are using or proposing different ways to find low-mass dark matter, McKinsey says. Some of them rely on the measurement of a single particle of light, called a photon, while others rely on signals from a single atomic nucleus or an electron, or a very slight collective vibration in atoms known as a phonon.

    Rather than ranking existing proposals, the report is intended to “marry the scientific justification to the possibilities and practicalities. We have motivation because we have ideas and we have the technology. That’s what’s exciting.”

    He says, “Physics is the art of the possible.”

    Editor's note: This article is adapted from an article originally published by Berkeley Lab.

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