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  • richardmitnick 7:12 am on October 24, 2017 Permalink | Reply
    Tags: , CERN, , , , ,   

    From CERN: “Meet the DUNEs” 

    Cern New Bloc

    Cern New Particle Event

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    CERN

    23 Oct 2017
    Sarah Charley, Symmetry

    1
    Inside one of the protoDUNE detectors, currently under construction at CERN (Image: Max Brice/CERN)

    A new duo is living in CERN’s test beam area. On the outside, they look like a pair of Rubik’s Cubes that rubbed a magic lamp and transformed into castle turrets. But on the inside, they’ve got the glamour of a disco ball.

    These 12m x 12m x 12m boxes are two prototypes for the massive detectors of the Deep Underground Neutrino Experiment (DUNE). DUNE, an international experiment hosted by Fermilab [FNAL] in the United States, will live deep underground and trap neutrinos: tiny fundamental particles that rarely interact with matter.

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    “Learning more about neutrinos could help us better understand how the early Universe evolved and why the world is made of matter and not antimatter,” said Stefania Bordoni, a CERN researcher working on neutrino detector development.

    These DUNE prototypes are testing two variations of a detection technique first developed by Nobel laureate Carlo Rubbia. Each cube is a chilled thermos that will hold approximately 800 of liquid argon. When a neutrino bumps into an atom of argon, it will release a flash of light and a cascade of electrons, which will glide through the electrically charged chamber to detectors lining the walls.

    Inside their reinforced walls sits a liquid-tight metallic balloon, which can expand and contract to accommodate the changing volume of the argon as it cools from a gas to a liquid.

    Even though theses cubes are huge, they are mere miniature models of the final detectors, which will be 20 times larger and hold a total of 72 000 tonnes of liquid argon.

    In the coming months, these prototypes will be cooled down so that their testing can begin using a dedicated beam line at CERN’s SPS accelerator complex.

    See the full article here.

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  • richardmitnick 8:09 pm on October 13, 2017 Permalink | Reply
    Tags: , Baby MIND, , CERN, , , ,   

    From CERN: “Baby MIND born at CERN now ready to move to Japan” 

    Cern New Bloc

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    CERN

    13 Oct 2017
    Stefania Pandolfi

    1
    Baby MIND under test on the T9 beamline at the Proton Synchrotron experimental hall in the East Area, summer 2017 (Image: Alain Blondel/University of Geneva)

    A member of the CERN Neutrino Platform family of neutrino detectors, Baby MIND, is now ready to be shipped from CERN to Japan in 4 containers to start the experimental endeavour it has been designed and built for. The containers are being loaded on 17 and 18 October and scheduled to arrive by mid-December.

    Baby MIND is a 75-tonne neutrino detector prototype for a Magnetised Iron Neutrino Detector (MIND). Its goal is to precisely identify and track positively or negatively charged muons – the product of muon neutrinos from the (Tokai to Kamioka) beam line, interacting with matter in the WAGASCI neutrino detector, in Japan.

    T2K map, T2K Experiment, Tokai to Kamioka, Japan

    The more detailed the identification of the muon that crosses the Baby MIND detector, the more we can learn about the original neutrino, in view of contributing to a more precise understanding of the neutrino oscillations phenomenon*.

    The journey of these muon neutrinos starts from the Japan Proton Accelerator Research Complex (J-PARC) in Tokai. They travel all the way to the Super-Kamiokande Detector in Kamioka, some 295 km away.

    Super-Kamiokande Detector, located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    On their journey, the neutrinos pass through the near detector complex building, located 280 m downstream from Tokai, where the WAGASCI + Baby MIND suite of detectors are. Baby MIND aims to measure the velocity and charge of muons produced by the neutrino interactions with matter in the WAGASCI detector. Muons precise tracking will help testing our ability to reconstruct important characteristics of their parent neutrinos. This, in turn, is important because in studying muon neutrino oscillations on their journey from Tokai to Kamioka, it is crucial to know how strongly and how often they interact with matter.

    Born from prototyping activities launched within the AIDA project, since its approval in December 2015 by the CERN Research Board, the Baby MIND collaboration – comprising CERN, University of Geneva, the Institute of Nuclear research in Moscow, the Universities of Glasgow, Kyoto, Sofia, Tokyo, Uppsala and Valencia – has been busy designing, prototyping, constructing and testing this detector. The magnet construction phase, which lasted 6 months, was completed in mid-February 2017, two weeks ahead of schedule.

    The fully assembled Baby MIND detector was tested on a beam line (link sends e-mail) at the experimental zone of the Proton Synchrotron in the East Hall during Summer 2017. These tests showed that the detector is working as expected and, therefore, ready to go.

    2
    Baby MIND under test on the T9 beamline at the Proton Synchrotron experimental hall in the East Area, summer 2017 (Image: Alain Blondel/University of Geneva)

    *Neutrino oscillations

    Neutrinos are everywhere. Each second, several billion of these particles coming from the Sun, the Earth and our galaxy, pass through our bodies. And yet, they fly past unnoticed. Indeed, despite their cosmic abundance and ubiquity, neutrinos are extremely difficult to study because they hardly interact with matter. For this reason, they are among the least understood particles in the Standard Model (SM) of particle physics.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    What we know is that they come in three types or ‘flavours’ – electron neutrino, muon neutrino and tau neutrino. Since their first detection in 1956, and until the late 1990s neutrinos were thought to be massless, in line with the SM predictions. However, a few years later, the Super-Kamiokande experiment in Japan and then the Sudbury Neutrino Observatory in Canada independently demonstrated that neutrinos can change (oscillate) from one flavour to another spontaneously.

    Sudbury Neutrino Observatory, , no longer operating

    This is only possible if neutrinos have masses, however small, and the probability of changing flavour is proportional to their difference in mass and the distance they travel. This ground-breaking discovery was awarded with the 2015 Physics Nobel Prize.

    See the full article here.

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    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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    CERN ATLAS New

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    CMS
    CERN CMS New

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    CERN LHCb New II

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  • richardmitnick 7:57 am on October 5, 2017 Permalink | Reply
    Tags: , AARNet and CERN sign MOU for developing cloud storage technologies, CERN   

    From AARnet: “AARNet and CERN sign MOU for developing cloud storage technologies” 

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    AARNet

    AARNet and CERN sign MOU for developing cloud storage technologies

    1
    Inside CERN’s Computing Centre. Photo: CERN

    September 20, 2017

    AARNet and CERN (the European Organization for Nuclear Research) recently signed a formal agreement which establishes a framework for ongoing collaborations to develop cloud storage technologies for the benefit of scientific and education communities globally.

    Both organisations share interests in enabling new and more efficient ways of collaborating to support international research endeavours, particularly around innovation for data storage, data transfer and data sharing.

    For the past two years, AARNet engineers have been collaborating with the CERN IT Storage Group to test distributed deployments of large-scale storage systems. The AARNet network’s capabilities for moving huge volumes of data across Australia’s vast continent is helping to inform research for advancing networking and data services for science.

    AARNet and CERN have also been collaborating to promote the creation of a community of cloud-technology adopters to share innovative solutions and operational best practices, co-organising events such as the CS3 (Cloud Services for Synchronisation and Sharing) conferences and workshops.

    Under the new agreement, the organisations will work together on developing solutions, such as the AARNet CloudStor service which is building on CERN’s EOS. The CERNBox and SWAN services will also be part of this collaboration.

    All these cloud-based services support the management of data storage, access and analysis for a range of users. EOS is a low latency heavy duty data storage infrastructure designed for the data deluge from Large Hadron Collider high energy physics experiments; CERNBox, is a cloud storage service meeting the unique needs of non-high-energy physics CERN users; SWAN, is a platform for performing interactive data analysis in the cloud via a web browser; and CloudStor is a data sharing and service with a wide range of research applications designed to meet the unique needs of the Australian research community.

    See the full article here .

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    AARNet provides critical infrastructure for driving innovation in today’s knowledge-based economy

    Australia’s Academic and Research Network (AARNet) is a national resource – a National Research and Education Network (NREN). AARNet provides unique information communications technology capabilities to enable Australian education and research institutions to collaborate with each other and their international peer communities.

     
  • richardmitnick 8:25 pm on September 21, 2017 Permalink | Reply
    Tags: CEA-Saclay IRFU, CERN, , European EuCARD programme, FRESCA2, Future Circular Collider   

    From CERN: “Next stop: the superconducting magnets of the future” 

    Cern New Bloc

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    CERN

    21 Sep 2017
    Corinne Pralavorio

    1
    The FRESCA2 cryostat before the insertion of the magnet. (Image: Sophia Bennett)

    The superconducting magnets of the future are under development and CERN is on the front line. To increase the energy of circular colliders, physicists are counting on ever more powerful magnets, capable of generating magnetic fields way beyond the 8 Tesla produced by the magnets in the Large Hadron Collider (LHC).

    Magnets generating fields of almost 12 Tesla, based on a superconducting niobium-tin compound, are already being manufactured for the High-Luminosity LHC.

    But CERN and its partners have also started work on the next generation of magnets, which will need to be capable of generating fields of 16 Tesla and more, for the colliders of the future such as those under consideration in the FCC (Future Circular Collider) study.

    2

    To achieve this goal, the performance of niobium-tin superconducting cable is being pushed to the limits.

    One of the key steps in the programme is the development of a test station capable of testing the new cables in realistic conditions, i.e. in a strong magnetic field. Such a facility, in the form of a dipole magnet with a large aperture, has been set up at CERN. The magnet, known as FRESCA2, was developed as part of a collaboration between CERN and CEA-Saclay in the framework of the European EuCARD programme.

    At the start of August, FRESCA2 reached an important milestone when it achieved its design magnetic field, generating 13.3 Tesla at the centre of a 10-centimetre aperture for 4 hours in a row – a first for a magnet with such a large aperture. By comparison, the current magnets in the LHC generate fields of around 8 Tesla at the centre of a 50-millimetre aperture. The development and performance of FRESCA2 were presented today at the EUCAS 2017 conference on superconductors and their applications.

    Testing of the cables under the influence of a strong magnetic field is a vital step. “We not only need to test the maximum current that can be carried by the cable, but also all the effects of the magnetic field. The quality of the field must be perfect,” explains Gijs De Rijk, deputy leader of the Magnets, Superconductors and Cryostats group at CERN. The precision with which the intensity of the magnetic field can be adjusted is an important feature for an accelerator. When the energy of the beams is increased, the intensity of the field that guides them must be increased gradually, without sudden spikes, or the beams could be lost. The fact that the magnets in the LHC can be adjusted with a great degree of precision, keeping their magnetic fields stable, is what allows the beams to circulate in the machine for hours at a time.

    3
    The FRESCA2 magnet before the start of the tests. (Image: Maximilien Brice/CERN)

    The two coils of FRESCA2 are formed from a superconducting cable made of niobium-tin. Their temperature is maintained at 2 degrees above absolute zero. The magnet they form is much larger than an LHC magner, measuring 1.5 metres in length and 1 metre in diameter. This allows the magnet to have a large aperture, measuring 10 centimetres, so that it can house the cables being tested, as well as sensors to observe their behaviour. FRESCA2 will also be used to test coils formed from high-temperature superconductors (an article on this subject will be published tomorrow).

    FRESCA2 is being modified so that by the end of this year it will be able to generate an even stronger field. The station will then be ready to receive the samples to be tested.

    See the CEA-Saclay IRFU (Institute of Research into the Fundamental Laws of the Universe) article.

    See the full article here.

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    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

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  • richardmitnick 11:23 am on September 4, 2017 Permalink | Reply
    Tags: , , CERN, Constructive interference: CERN and gravitational waves   

    From CERN: “Constructive interference: CERN and gravitational waves” 

    Cern New Bloc

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    CERN

    4 Sep 2017
    Stefania Pandolfi

    1
    Gravitational waves as emitted during a black hole merger. (Image credit: S. Ossokine, A. Buonanno, Max Planck Institute for Gravitational Physics, Simulating eXtreme Spacetimes project, D. Steinhauser, Airborne Hydro Mapping GmbH)

    What do gravitational waves – ripples in the fabric of space-time caused by violent energetic processes in the universe – have to do with particle physics? At first sight, not much. But on 1 September scientists from the gravitational-wave community and CERN met to identify technology parallels.

    As CERN works towards a major upgrade of the Large Hadron Collider (LHC), the High Luminosity LHC, gravitational wave scientists are also contemplating major upgrades to current facilities. These will enrich the vista of the universe opened up in February 2016 when the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo collaborations announced the long-awaited first detection of gravitational waves, 100 years after their prediction by Einstein’s theory of gravity: general relativity.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Gravitational waves were detected using large “interferometers”. These L-shaped tubes with 4-km-long arms contain a series of mirrors and lasers that are sensitive to any slight distortion in the apparatus caused by a passing gravitational wave.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    Now the gravitational-wave community is exploring several technologies to improve the sensitivity of the current observatories.

    “Technological R&D and design efforts for third-generation gravitational detectors may have interesting overlaps both with CERN capabilities and possible future directions,” says Barry Barish of the California Institute of Technology, one of the founders of the LIGO experiment.

    Next-generation interferometers could have much longer arms, be located underground to reduce seismic noise, or be cooled to cryogenic temperatures to reduce thermal interference. Expertise in vacuum, cryogenics and control systems is therefore of particular relevance, as well as how to deal with large volumes of data. CERN can also offer insights into how to organise the large international collaborations necessary to design, build and operate tomorrow’s gravitational wave observatories.

    More precise observations of the gravitational fingerprints of the most energetic phenomena in our universe may also help CERN in its quest to understand the fundamental constituents of matter. Collisions of black holes or neutron stars and supernovae explosions, for example, could shed light on open questions such as the nature of dark matter, the limits of the validity of general relativity and the behaviour of matter at extreme densities and pressures.

    “Overall, we had a healthy exchange of ideas that opened the door to the exploration of possible further synergies and joint work,” said Barish.

    See the full article here.

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    Meet CERN in a variety of places:

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    THE FOUR MAJOR PROJECT COLLABORATIONS

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    CERN ATLAS New

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    CERN CMS New

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  • richardmitnick 1:01 pm on September 2, 2017 Permalink | Reply
    Tags: , , CERN, , , , ,   

    From STFC: “World’s largest x-ray laser facility is now open to users” 


    STFC

    http://www.stfc.ac.uk/news/worlds-largest-x-ray-laser-facility-is-now-open-to-users/

    1 September 2017
    Becky Parker-Ellis
    STFC Media office
    01793 444564

    1
    The main linac driving the European XFEL, suspended from the ceiling to leave space at floor level, photographed in January 2017. (Image: D Nölle/DESY).

    The global science community is celebrating the official inauguration of the world’s largest X-ray laser at the international research facility, the European XFEL. This event marks the start of user operation after eight years of construction.

    European XFEL is located in Hamburg and Schleswig-Holstein in Germany, and is capable of generating extremely intense X-ray laser flashes that will offer new research opportunities for scientists across the world.

    UK scientists at the Science and Technology Facilities Council (STFC) have played a significant role in the creation of XFEL, by designing and creating the Large Pixel Detector (LPD) – a cutting edge X-ray camera that can capture images of ultrafast processes such as chemical reactions.

    In addition to the LPD, designed and built by STFC’s Technology Division, STFC’s Central Laser Facility is currently building a DiPOLE100 laser for the European XFEL (directly funded by STFC and EPSRC), where it will be used to recreate the conditions found within stars.

    The UK will soon be extending its relationship with XFEL by signing a partnership agreement, allowing UK researchers access to the facility through an STFC-managed subscription. The formal procedures of accession for the UK to join XFEL are underway. In anticipation of this being completed in the coming months the UK has already contributed the majority of its commitment towards the construction costs of the facility.

    Dr Brian Bowsher, Chief Executive of STFC, said: “The UK, through STFC, is already contributing a great deal to this project in terms of equipment and expertise, and we are looking forward to ratifying formally the UK’s involvement in XFEL. XFEL offers many exciting opportunities to the research community and STFC is delighted to support the UK’s involvement with this international facility.

    “Being asked to design and build significant technological infrastructure for XFEL is recognition of the leading reputation STFC’s technology and engineering teams have on the world’s stage.”

    About European XFEL

    The European XFEL is an international research facility of superlatives: 27,000 X-ray flashes per second and a brilliance that is a billion times higher than that of the best conventional X-ray sources will open up completely new opportunities for science. Research groups from around the world will be able to map the atomic details of viruses, decipher the molecular composition of cells, take three-dimensional “photos” of the nanoworld, “film” chemical reactions, and study processes such as those occurring deep inside planets. The construction and operation of the facility is entrusted to the European XFEL GmbH, a non-profit company that cooperates closely with the research centre DESY and other organisations worldwide.

    The company, which has a workforce of about 300 employees, entered in its operating phase on 4 July and has selected the first 14 groups of scientists to carry out their ambitious research projects at the facility from September 2017, including a team from the UK. With construction and commissioning costs of 1.22 billion euro (at 2005 price levels) and a total length of 3.4 kilometres, the European XFEL is one of the largest and most ambitious European research projects to date. At present, 11 countries have signed the European XFEL convention: Denmark, France, Germany, Hungary, Italy, Poland, Russia, Slovakia, Spain, Sweden, and Switzerland. The United Kingdom is in the process of joining.

    STFC and XFEL

    In December 2014 the UK government announced that the UK would invest up to £30M (about 38 M€) to become a full member of the European XFEL as the result of the input received to the BIS Capital Consultation exercise. The UK will become the 12th member of the European XFEL project and STFC is now working with the European XFEL project and the other partners to negotiate UK membership.

    Diamond and XFEL

    The UK, through STFC-funded Diamond Light Source, is also the host for the UK’s XFEL hub. Housed within the existing Diamond infrastructure, the hub will enable users to fully prepare for their experiments with currently operating XFELs and the European XFEL when it comes online in Hamburg in 2017. The UK Hub (which is directly supported by MRC, BBSRC and the Wellcome Trust) will provide support in terms of sample preparation, data processing and training. There will also be a dedicated fibre link from Hamburg to Harwell enabling users to carry out data analysis back in the UK, with support from the UK Hub team.

    From CERN

    The European XFEL is the culmination of a worldwide effort, with European XFEL GmbH being responsible for the construction and operation of the facility, especially the X-ray photon transport and experimental stations, and its largest shareholder DESY leading the construction and operation of the electron linac. The facility joins other major XFELs in the US (LCLS) and Japan (SACLA), and is expected to keep Europe at the forefront of X-ray science for at least the next 20 to 30 years.

    Construction of the €1.2 billion European XFEL began in January 2009, funded by 11 countries, with Germany and Russia as the largest contributors, although no fewer than 17 European institutes contributed in-kind to the accelerator complex. “The European XFEL is the result of intense technological development in a worldwide collaboration that has exceeded expectations,” says Eckhard Elsen, CERN’s Director for Research and Computing. “It is an impressive example of how cutting-edge accelerator research can benefit society, and demonstrates the continuing links between the needs of fundamental research in particle physics and X-ray science.”

    A full account of the European XFEL and its superconducting linac, which appeared in the CERN Courier July/August 2017 issue, can be read here.

    3
    The European XFEL facility in Hamburg (on the right) and Schenefeld (Schleswig-Holstein) (Image: European XFEL)

    See the full STFC article here .
    See the full CERN article here .

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    STFC Hartree Centre

    Helping build a globally competitive, knowledge-based UK economy

    We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

    Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
    Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
    National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
    Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

    We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

    STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

    Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

    They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

    Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

    The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

    We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

    Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

     
  • richardmitnick 12:57 pm on August 30, 2017 Permalink | Reply
    Tags: CERN, , Extra dimensions, Heavy sterile neutrinos, Higgs siblings, Hunting season at the LHC, , Long-lived particles, New vector bosons, Quantum black holes, Quark substructure, Supersymmetric particles   

    From CERN: “Hunting season at the LHC” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    10 Aug 2017
    Matthew Chalmers
    Stefania Pandolfi

    1
    Like hunters following the tracks of their prey, physicists compare real collision data with simulations of what they expect to see if a new particle is produced and decays in their detectors. (Supersymmetry simulation image: the CMS collaboration)

    With the LHC now back smashing protons together at an energy of 13 TeV, what exotic beasts do physicists hope to find in this unfamiliar corner of the natural world?

    Among the top priorities for the LHC experiments this year is the hunt for new particles suspected to lurk at the high-energy frontier: exotic beasts that do not fit within the Standard Model of particle physics and could lift the lid on an even deeper theory of nature’s basic workings.

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    New particles predicted by specific models of physics beyond the
    Standard Model (Image: Daniel Dominguez, with permission from Hitoshi Murayama)

    Following the discovery of the Higgs boson five years ago, which was the final missing piece of the Standard Model of particle physics, physicists have good reason to expect that new particle species lie over the horizon. Among them is the mystery of what makes up dark matter, why the Standard Model particles of matter weigh what they do and come in three families of two, and, indeed, why the Higgs boson isn’t vastly heavier than it is – that is, why it isn’t so heavy that it could have ended the evolution of the universe an instant after the Big Bang.

    Casting the net wide

    These outlandish prey are just a few of the known unknowns for physicists. To ensure that no corner of the new-physics landscape is left unturned, the LHC experiments also employ a model-independent approach to search for general features such as pairs of high-energy quarks and leptons or for unexplained sources of missing energy.

    Their most elusive quarry might not light up their detectors at all, forcing the LHC exploration teams to adopt stealth approaches, such as making ultra-precise measurements of known Standard Model processes and seeing if they diverge from predictions. While physicists are hoping for a clear shot at any new particle species – a distinctive “bump” in the data that can only be explained by the presence of a new, heavy particle – they could be faced with a mere rustling in the undergrowth or other indirect signs that something is awry. This quest is not just the preserve of all of the LHC experiments, but also of numerous other experiments at CERN that are not linked to the LHC.

    Either way, physicists exploring this uncharted territory of the high-energy frontier have to take extreme care not to get tricked by numerous Standard Model doppelgängers or be teased by inconclusive statistics. Even after an exotic new beast has been snared statistically and it seems that the LHC experiments have a discovery on their hands, so begins the task of identifying what the beast really is: a mere mutant or close relative of a species we already know? Or the first glimpse of a new subatomic kingdom?

    Ranging from the bizarre to the mind-boggling, and in no particular order, below is a summary of some of the quantum creatures that are in the LHC experimentalists’ sights this year.

    Supersymmetric particles
    What?
    For more than 40 years, physicists have been beguiled by a hypothetical symmetry of space–time called supersymmetry (SUSY), which would imply that every particle in the Standard Model has a partner called a “sparticle”. Given that these have not yet been seen, they must be heavier than the standard version.
    Why?
    Considered by many to be mathematically beautiful, SUSY can settle some of the technical problems with the Standard Model and suggests ways in which the fundamental forces may be unified. The lightest SUSY particle is also a good candidate to explain what makes up dark matter.
    How?
    SUSY could reveal itself in many ways in the LHC’s ATLAS and CMS experiments, for instance in events in which much of the energy is carried away by massive, weakly interacting sparticles. Like previous colliders, the LHC has so far found no evidence for supersymmetry, which rules out the existence of certain types of sparticles below a mass of 2 TeV.

    Higgs siblings
    What?
    The Standard Model demands just one type of Higgs boson, and so far it seems that the observed Higgs particle fits the requirements. However, many theories suggest that this standard Higgs is one of a wider family of Higgs particles with slightly different properties – SUSY predicts no less than five of them.
    Why?
    Since the Higgs boson, which gives the Standard Model particles their masses, is a fundamentally different “scalar” object compared to all other known particles, it could open the door to new physics domains.
    How?
    Exotic cousins of the Higgs have different electrical charges and other properties, especially their mass, forcing them to decay differently to the standard Higgs in ways that should be relatively easy to spot.

    New vector bosons
    What?
    At the quantum level, nature’s fundamental forces are mediated by elementary particles called vector bosons: the neutral photon for electromagnetism, and the neutral Z or charged W bosons for the weak nuclear force responsible for radioactive decay. In principle, additional vector bosons – known as W’ and Z’ – could exist, too.
    Why?
    Finding such particles would constitute the discovery of a fifth force of nature, radically changing our view of the universe and extending the structure of the Standard Model.
    How?
    Experimental signatures of new vector bosons, which presumably are heavier than the W and Z, otherwise they would have been spotted by now, range from direct production in ATLAS and CMS to more subtle signs of lepton flavour violation in LHCb.

    Extra dimensions
    What?
    The possible existence of additional dimensions of space beyond the three we know of was put forward in the late 1990s to nurse some of the Standard Model’s ills. In this picture, the entire universe could merely be a 3D “brane” floating through a higher-dimensional bulk, to which the Standard model particles are forever shackled while leaving the force of gravity to propagate freely in the bulk, or there could be additional microscopic dimensions at extremely small scales.
    Why?
    If true, it would allow physicists to study gravitons and other gravitational phenomena in the lab, as it would shift the scale of quantum gravity by many orders of magnitude, right down to the TeV scale where the LHC operates.
    How?
    The presence of extra dimensions could produce a clear missing-energy signal in the ATLAS and CMS detectors and lead to “resonances”, like notes on a guitar string, that correspond to invisible relatives of the hypothetical carrier of gravity: the graviton.

    Quantum black holes
    What?
    If extra dimensions exist, implying gravity is stronger than we thought, it is possible for very light black-holes to exist – mathematically resembling a conventional astrophysical black hole but trillions and trillions of times lighter. Such a state is predicted to evaporate more or less as soon as it formed and therefore poses no danger. After all, if such creatures are created at high energies, then they are also created all the time in collisions between cosmic rays and the upper atmosphere without doing any apparent harm.
    Why?
    The discovery of a miniature black hole would revolutionise physics and accelerate efforts to create a quantum theory of gravity that unites quantum mechanics with Einstein’s general theory of relativity.
    How?
    Miniature black holes would decay or “evaporate” instantly into other particles, revealing themselves as events containing multiple particles.

    Dark matter
    What?
    The Standard Model, while passing every test on Earth, can only account for 5% of the matter observed in the universe as a whole. It is presumed that the dark matter known to exist from astronomical observations is made of some kind of particle, perhaps a supersymmetric particle, but precisely which type is a still a mystery.
    Why?
    In addition to explaining a large fraction of the universe, the ability to study dark matter in the laboratory would open a rich and fascinating new line of experimental study.
    How?
    Dark matter interacts very weakly, if at all, via the standard forces, and would leave a characteristic missing-energy signature in the ATLAS and CMS detectors.

    Leptoquarks
    What?
    The Standard Model contains two basic types of matter: quarks, which make up protons and neutrons; and leptons, such as electrons and neutrinos. Leptoquarks are hypothetical particles that are a bit of both, allowing quarks and leptons to transform into one another.
    Why?
    Leptoquarks appear in certain extensions of the Standard Model, in particular in attempts to unify the strong, weak and electromagnetic interactions.
    How?
    Since they are expected to decay into a lepton and a quark, searches at the LHC look for characteristic bumps in the mass distributions of decay products.

    Quark substructure
    What?
    All the experimental evidence so far indicates that the six types of quarks we know of are indivisible, but history has shown us to be wrong on this front with other particles, not least the atom. Exploring matter at smaller scales, it is natural to ask: are quarks really the smallest entities, or do they possess components inside them?
    Why?
    If found, quark substructure would prove that there is a whole new layer of the subatomic world that we do not yet know about. The existence of “preons” has been postulated to give an explanation at a more fundamental level to the table of elementary particles and forces, with the aim of replicating the successful ordering of the periodic table.
    How?
    The experimental signature of the compositeness of quarks can be the detection of the decay of a quark in an excited state into ordinary quarks and gluons, which will in turn produce two streams of highly-energetic collimated particles called jets.

    Heavy sterile neutrinos
    What?
    The Standard Model involves three types of light neutrinos – electron, muon and tau neutrinos – but several puzzles, such as the very small mass of regular neutrinos, suggest that there might be additional, sterile neutrinos, much heavier than the regular ones.
    Why?
    If found, a heavy sterile neutrino can help solve the problem of matter-antimatter asymmetry in the universe. It could also be a candidate for dark matter, in addition to accounting for the small masses of the regular, non-sterile neutrinos, which cannot be otherwise explained in the framework of the Standard Model.
    How?
    The mass of sterile neutrinos is theoretically unknown, but their presence could be revealed when they “oscillate” into regular, flavoured neutrinos.

    Long-lived particles
    What?
    New particles produced in a particle collision are generally assumed to decay immediately, almost precisely at their points of origin, or to escape undetected. However, many models of new physics include heavy particles with lifetimes large enough to allow them to travel distances ranging from a few micrometres to a few hundred thousand kilometres before decaying into ordinary matter.

    Why?
    Heavy, long-lived particles can help explaining many of the unsolved questions of the Standard Model, such as the small mass of the Higgs boson, dark matter, and perhaps the imbalance of matter and antimatter in the universe.

    How?
    Long-lived particles could appear like a stream of ordinary matter spontaneously appearing out of nowhere (“displaced vertices”). Other ways to search for them include looking for a large “dE/dx”, long time of flight or tracks disappearing in the detector.

    See the full article here.

    Please help promote STEM in your local schools.

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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 2:01 pm on August 28, 2017 Permalink | Reply
    Tags: , CERN, , Neutrino science,   

    From CERN: “Construction of the protoDUNE detectors begins” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    28 Aug 2017
    Stefania Bordoni

    1
    The first Anode Plane Assembly module, which will collect signals from particles passing through the protoDUNE single-phase detector, has recently arrived at CERN. (Image: Julien Marius Ordan/CERN)

    Two large neutrino detectors, the single- and dual-phase protoDUNE modules, are being built at CERN. They are prototypes of the future Deep Underground Neutrino Experiment (DUNE) detector, the construction of which has recently begun in the United States.

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


    FNAL DUNE Argon tank at SURF


    Surf-Dune/LBNF Caverns at Sanford



    SURF building in Lead SD USA

    Each of these detectors is a 10x10x10-metre Liquid Argon Time Projection Chamber, with a single- (SP) or dual-phase (DP) configuration, containing about 800 tonnes of liquid argon. While the two big cryostats housing the detectors are about to be completed, the construction of the protoDUNE-SP detector has just started, following the arrival of two key components.

    The first Anode Plane Assembly module, which will collect signals from particles passing through the detector, has recently arrived at CERN. It will be tested, together with its electronics, before being installed in its final position inside the cryostat. The protoDUNE-SP detector will have six of these modules, which are 6 metres high and 2.5 metres wide. They are currently being built in the UK and US and will be shipped to CERN within the next few months.

    2
    The first field-cage module of the protoDUNE-SP detector has been fully assembled at CERN. (Image: Julien Marius Ordan/CERN)

    In parallel, other parts of the protoDUNE-SP detector are being assembled at CERN, including the field cage, which keeps the electrical field uniform inside the volume of the detector, where particles are revealed. This is important because the electrical signal released by ionising particles crossing the detector is extremely small, so a perfectly uniform electrical field is needed to avoid introducing spurious signals. Four of the 28 field-cage modules have already been assembled and are stored in the EHN1 hall, ready to be installed.

    The assembly and installation of the detector parts is expected to be completed by spring next year, in order to have protoDUNE-SP ready to take data in autumn 2018, before the two-year scheduled shutdown of the LHC.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier

    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS
    CERN ATLAS New

    ALICE
    CERN ALICE New

    CMS
    CERN CMS New

    LHCb
    CERN LHCb New II

    LHC

    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

     
  • richardmitnick 4:26 pm on August 11, 2017 Permalink | Reply
    Tags: CERN, , Supercomputing together   

    From CERN and SKA: “SKA and CERN co-operate on extreme computing” 

    SKA Square Kilometer Array

    1
    Big-data co-operation agreement

    On 14 July, the Square Kilometre Array (SKA) organisation signed an agreement with CERN to formalize their collaboration in the area of extreme-scale computing. The agreement will address the challenges of “exascale” computing and data storage, with the SKA and the Large Hadron Collider (LHC) to generate an overwhelming volume of data in the coming years.

    When completed, SKA will be the world’s largest radio telescope with a total collecting area of more than 1 km2 using thousands of high-frequency dishes and many more low- and mid-frequency aperture array telescopes distributed across Africa, Australia and the UK. Phase 1 of the project, representing approximately 10% of the final array, will generate around 300 PB of data every year – 50% more than has been collected by the LHC experiments in the last seven years. As is the case at CERN, SKA data will be analysed by scientific collaborations distributed across the planet. The acquisition, storage, management, distribution and analysis of such volumes of scientific data is a major technological challenge.

    “Both CERN and SKA are and will be pushing the limits of what is possible technologically, and by working together and with industry, we are ensuring that we are ready to make the most of this upcoming data and computing surge,”says SKA director-general Philip Diamond.

    CERN and SKA have agreed to hold regular meetings to discuss the strategic direction of their collaborations, and develop demonstrator projects or prototypes to investigate concepts for managing and analysing exascale data sets in a globally distributed environment. “The LHC computing demands are tackled by the Worldwide LHC computing grid, which employs more than half a million computing cores around the globe interconnected by a powerful network,” says CERN’s director of research and computing Eckhard Elsen. “As our demands increase with the planned intensity upgrade of the LHC, we want to expand this concept by using common ideas and infrastructure into a scientific cloud. SKA will be an ideal partner in this endeavour.”

    See the full article here .

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  • richardmitnick 9:12 pm on August 2, 2017 Permalink | Reply
    Tags: , CERN, , , The race to reveal antimatter’s secrets   

    From Nature: “The race to reveal antimatter’s secrets” 

    Nature Mag
    Nature

    02 August 2017
    Elizabeth Gibney

    1
    A laboratory at CERN hosts the only usable source of antiprotons, the proton’s antimatter counterpart. Maximilien Brice/CERN

    In a high-ceilinged hangar at CERN, six rival experiments are racing to understand the nature of one of the Universe’s most elusive materials. They sit just metres apart. In places, they are literally on top of one another: the metallic beam of one criss-crosses another like a shopping-centre escalator, its multitonne concrete support hanging ominously overhead.

    “We’re constantly reminded of each other,” says physicist Michael Doser, who leads AEGIS, an experiment that is vying to be the first to discover how antimatter — matter’s rare mirror image — responds to gravity.

    2
    AEgIS experiment installation

    Doser and his competitors have little choice but to get cosy. CERN, Europe’s particle-physics laboratory near Geneva, Switzerland, boasts the world’s only source of antiprotons — particles that seem identical to protons in every way except for their opposite charge and spin. The lab’s Antiproton Decelerator is a ring, 182 metres around, that feeds from the same accelerators as the lab’s bigger and more famous sibling, the Large Hadron Collider (LHC).

    CERN Antiproton Decelerator

    Antiprotons enter the machine travelling close to the speed of light. As the name implies, the decelerator slows the particles down, providing a stream of antiprotons from which experiments must take turns to sip. All this must be done carefully; upon meeting matter, the antiparticles vanish in a puff of energy.

    For decades, scientists have worked to pin down antiprotons, and the antihydrogen atoms they can be used to build, for long enough to study. The past few years have seen rapid advances: experimentalists can now control enough antiparticles to start probing antimatter in earnest and to perform increasingly precise measurements of its fundamental properties and internal structure. Jeffrey Hangst, who leads the experiment known as ALPHA, says that in principle at least, his team can now do with antihydrogen anything others do with hydrogen. “For me, this period is what I’ve worked towards for 25 years,” he says.

    CERN ALPHA Antimatter Factory

    The experiments have a lot riding on them: even a slight difference between the properties of matter and antimatter could explain why anything exists at all. As far as physicists know, matter and antimatter should have been created in equal amounts in the early Universe and so blasted each other into oblivion. But that didn’t happen, and the origin of this fundamental imbalance remains one of the biggest mysteries in physics.

    The CERN efforts are unlikely to crack the case any time soon. Antimatter has so far proved maddeningly identical to matter, and many physicists think it will remain that way, because any difference would shake the foundations of modern physics. But the six experiments, the latest in a line of investigations that began at CERN more than 30 years ago, are attracting attention as the LHC continues to draw a blank in its hunt for particles that could explain the antimatter paradox. Moreover, the teams’ rapid advances in manipulating antimatter have earned them a major upgrade to the facility’s antiproton factory — a cutting-edge decelerator that will start operation by the end of this year and eventually enable experiments to work with up to 100 times more particles.

    The dozens of physicists working on the CERN experiments know they face a tough challenge. Antimatter is exasperating to work with, the competition between teams is intense and the odds of finding anything new seem low. But CERN’s antimatter wranglers are motivated by the thrill of opening a new window on the Universe. “These are such tour de force experiments that, no matter what answer you get, you can be proud that you do this,” says Hangst. There’s no guarantee that antimatter will yield a major discovery. But “if you can get your hands on some”, he says, “it would be completely reprehensible not to look.”

    The fact of the matter

    The roots of antimatter physics can be traced to 1928, when British physicist Paul Dirac wrote an equation that described an electron moving close to the speed of light[1]. Dirac realized that there had to be both a positive and a negative solution to his equation. He later interpreted this mathematical quirk as suggestive of the existence of an anti-electron, now called a positron, and theorized that antimatter equivalents should exist for every particle.

    Experimentalist Carl Anderson confirmed the positron’s existence in 1932, when he found a particle that seemed like an electron except that when it travelled through a magnetic field, its trajectory bent in the opposite direction. Physicists soon realized that positrons were routinely produced in collisions: smash particles together with enough energy and some of that energy can turn into matter–antimatter pairs.

    By the 1950s, researchers had begun to exploit this energy-to-particle conversion to produce antiprotons. But it took decades to find a way to make enough of them to capture and study. One motivation was the tantalizing idea that antiprotons and positrons could be paired to make antihydrogen, which could then be compared with the well-studied hydrogen atom (see ‘Wrangling antimatter’).

    Creating positrons is fairly straightforward. The particles are produced in certain types of radioactive decay, and can be readily caught with electric and magnetic fields. But the higher-mass antiproton is another story. Antiprotons can be made by slamming protons into a dense metal, but they emerge from such collisions moving too fast to be held by an electromagnetic trap.

    Antimatter hunters needed a way to massively slow down, or cool, the particles. CERN’s first dedicated attempt to decelerate and store antimatter began in 1982, with the Low Energy Antiproton Ring (LEAR). In 1995, the year before LEAR was slated to be shut down, a team used antiprotons from the facility to produce the first antihydrogen atoms [2].

    LEAR’s replacement, the Antiproton Decelerator, came online in 2000 with three experiments. Similar to its predecessor, it tames antiparticles, first by focusing them using magnets and then by slowing them using strong electric fields. Beams of electrons also exchange heat with the antiprotons, cooling but not touching them because the particle types are both negatively charged and so repel each other. The overall process slows the antiprotons to one-tenth of the speed of light. That is still too fast to work with, so each of the six experiments uses techniques to further slow and trap the antiprotons.

    There is plenty of attrition along the way. Each ‘shot’ of 30 million antiprotons fed to an experiment starts by smashing 12 trillion protons into a target. By the time Hangst’s ALPHA experiment, for example, has slowed its antiprotons enough to pair them with positrons and create antihydrogen, just 30 of the particles remain, the rest having escaped, been annihilated or been discarded because they are too fast or in the wrong condition to study. Experimenting with such tiny numbers of antiatoms is a real pain, says Hangst: “You get a whole new attitude about all the rest of physics when you have to work with this stuff.”

    Race for the prize

    Antimatter research at CERN will eventually have some competition from the Facility for Antiproton and Ion Research, a €1-billion (US$1.16-billion) international accelerator complex in Darmstadt, Germany, that will be completed around 2025.

    5
    Facility for Antiproton and Ion Research schematic. FAIR.
    7
    Facility for Antiproton and Ion Research campus. FAIR

    But for the moment, CERN has the monopoly on producing antiprotons slow enough to study.

    Today, there are five experiments running at the antimatter facility (one, GBAR, is still being built).

    CERN GBAR

    Each has its own way of working with antiprotons, and although some do unique experiments, they often compete to measure the same properties and independently corroborate each other’s values (see ‘The experiments’).

    4

    The experiments share one beam, which means that in any two-week period, just three of the five experiments get beam time, each taking their turn in an 8-hour shift. A weekly coordination meeting ensures that each experiment knows when its neighbours’ magnet will be running, so as not to ruin sensitive measurements. But despite the close proximity, teams usually find out about breakthroughs made by their neighbours by reading about them in a paper. “This is built on competition, and that’s good. That motivates you,” says Hangst.

    3

    Today, only one of the six experiments — BASE — directly studies the antiprotons from the Antiproton Decelerator.

    10
    BASE: Baryon Antibaryon Symmetry Experiment. CERN

    BASE holds the particles in a Penning trap, a complex array of electric fields (which pin particles vertically) and magnetic fields (which make them orbit in a circle). The team can store antiprotons for more than a year, and has used the orbits of antiprotons in the trap to determine the particle’s charge-to-mass ratio with record precision[3]. The group also uses a complex method to reveal the antiproton’s magnetic moment [4] — akin to its intrinsic magnetism. The measurement involves switching individual particles rapidly between two separate traps and detecting changes caused by minuscule shifts in an oscillating microwave field. Mastering the technique has become a passion for collaboration leader Stefan Ulmer, a physicist at RIKEN in Wako, Japan. “My entire heart is in this,” he says.

    4
    Source: CERN
    5
    6
    7
    8
    8
    9

    Antihydrogen, which is studied by the other experiments at CERN, comes with its own challenges. Because it has a neutral charge, it is immune to electric fields, and so nearly impossible to control. Experiments must exploit the antiatoms’ weak magnetic properties, restraining the particles with a ‘magnetic bottle’. For the bottle to work, the magnetic fields inside must vary enormously over a tiny distance, changing by 1 tesla — the strength of a car-lifting scrapyard magnet — over just 1 millimetre. Even so, the antihydrogen atoms must have a temperature of less than 0.5 kelvin, or they will escape.

    The first antihydrogen atoms, created using antiprotons on the move, lasted about 40 billionths of a second. In 2002, two experiments, ATRAP and ALPHA’s predecessor ATHENA, became the first to slow antiprotons enough to make significant amounts of antihydrogen, amassing many thousands of the atoms each[5]. The major breakthrough came almost a decade after that, when the teams learnt to trap the antiatoms for minutes at a stretch [6]. They have since measured properties such as charge and mass and used laser light to probe energy levels [7]. On page 66, ALPHA reports its latest advance: the most precise measurement yet of antihydrogen’s hyperfine structure, the tiny internal energy shifts caused by interactions between its antiproton and positron [8].

    Together, the CERN experiments explore a range of antimatter properties, any of which could display a difference from matter. The goal for all of them is to keep shrinking the uncertainty, says antimatter veteran Masaki Hori. He leads the ASACUSA experiment, which uses lasers to study antiatoms in flight, free from the disruptive forces of traps. Last year, the team made a precise measurement of the ratio of antiproton mass to electron mass, using exotic helium atoms in which an antiproton takes the place of an electron[9]. Like other measurements so far, it showed no difference between matter and antimatter. But each result is a more stringent test of whether matter and antimatter really are exact mirror images.

    What difference does it make?

    If the experiments were to detect any difference between matter and antimatter, it would be a radical discovery. It would mean the violation of a principle called charge, parity and time reversal (CPT) symmetry. According to this principle, a mirror-image Universe that is filled with antimatter and in which time runs backwards will have the same laws of physics as our own. CPT symmetry is the backbone of theories such as relativity and quantum field theory. Breaking it would, in a way, break physics. In fact, only exotic theories predict that the antimatter experiments will find anything at all.

    For this reason, the physicists at the LHC tend to view the antimatter researchers next door “with bemused attention”, says Doser, who has been working on antimatter for 30 years. “They think this stuff is fun and interesting, but unlikely to lead to something new,” he says. CERN theorist Urs Wiedemann seems to confirm that. He says that the experiments’ ability to manipulate antimatter is “mind-boggling” and that such tests of theory are essential, but “if you ask is there a firm physics motivation that at some accuracy something new will be discovered, I think a fair statement is, ‘No’”.

    Still, the LHC has fared little better in solving the antimatter mystery. Experiments dating back to the 1960s have shown that some physical processes, such as the decay of exotic kaon particles into more familiar ones, have tiny biases in favour of producing matter. LHC experiments have been hunting more such biases, and even a raft of as-yet-undiscovered particles whose behaviour in the early Universe could have accounted for the huge matter–antimatter imbalance that remains. There has been good reason to suspect such particles exist: they were predicted by supersymmetry, a theory that was proposed to tie up some troubling loose ends in particle physics. But no such particles have turned up in eight years of searching. Now, the simplest, most elegant versions of supersymmetry — the ones that made the idea appealing in the first place — have been largely ruled out. “Today, the LHC is looking for hypothetical particles, which may or may not be there, with very little guidance from theory. In a way, this is the same situation we’re in,” says Doser.

    10
    CERN’s new antiproton decelerator, ELENA, is set to start slowing the particles down for study this year. Maximilien Brice/CERN

    A few teams are now jumping into the next big challenge: the race to measure antimatter’s acceleration under gravity. Physicists generally expect antimatter to fall just like matter. But some fringe theories predict that it has ‘negative mass’ — it would be repelled by, rather than attracted to, matter. Antimatter with this property might account for the effects of dark energy and dark matter, the identities of which are still unknown. But most mainstream theorists say such a Universe would be inherently unstable.

    Up is down

    Measuring antihydrogen in free fall will, as ever, be a question of making it cool enough. Even the tiniest thermal fluctuations will mask the signal of a falling atom. And only neutral particles such as antihydrogen can be used, because even distant sources of electromagnetic fields can expose charged particles to forces bigger than gravity.

    Next year, Hangst’s group aims to use proven technology — a vertical version of its ALPHA experiment — to get a definitive determination of whether antimatter falls up or down. “Obviously I think we’ll succeed first, or I wouldn’t get into it,” he says. But two other experiments — Doser’s AEGIS and the antimatter facility’s newest member, GBAR — are hot on the team’s heels. Both use laser-cooling techniques to boost precision, which will enable them to pick up subtler differences between the acceleration of antimatter and matter than ALPHA currently can. AEGIS will measure the bend of a horizontal beam of antihydrogen, whereas GBAR will let its antiatoms free-fall for 20 centimetres. Both aim to bring the antiatoms’ temperature down to a few thousandths of a degree above absolute zero, allowing measurements of gravitational acceleration as sensitive as 1 part in 100, and have plans to go even further.

    Later this year, GBAR will be the first to benefit from ELENA, a new 25-million-Swiss-franc ($26-million), 30-metre-circumference ring that sits inside the Antiproton Decelerator and is designed to further slow the antiprotons coming from the machine.

    Eventually, ELENA will supply particles to all of the experiments, nearly simultaneously. The antiprotons will be slower by a factor of seven and arrive in sharper beams. Because they’ll be more efficiently cooled at early stages, experiments should be able to trap more of the particles.

    Now that the teams can manipulate and test antimatter, Hangst says, more and more physicists are becoming interested in the work. They even pitch ideas for experiments and values to check. And the groups are looking outwards, for ways in which their technologies could aid other areas of research. The GBAR team, for example, is working on a portable trap to carry antiprotons to a CERN experiment called ISOLDE, where they can be used to map the neutrons in unstable radioactive atoms.

    Assuming a technical impasse doesn’t grind progress to a halt, Doser reckons that by the end of the 2020s, physicists will be adept enough at handling antimatter to be able to replicate a range of atomic-physics feats, including constructing antimatter atomic clocks. “I see lots of ideas popping up now, and that’s a sign the field is moving forward quickly,” he says. “I hope CERN never kicks me out, because I’ve got plans for the next 30 years.”

    References

    See the full article, but there are no links

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

     
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