EPS awards prizes for high-energy physics
The high-energy and particle-physics division of the European Physical Society (EPS) has announced the winners of its 2017 prizes, awarded at the EPS Conference on High-Energy Physics held in Venice on 5–12 July.
The 2017 High Energy and Particle Physics Prize for an outstanding contribution to the field was awarded to Erik Heijne of Czech Technical University in Prague, Robert Klanner of the University of Hamburg and DESY, and Gerhard Lutz of the Max Planck Institute for Physics, “for their pioneering contributions to the development of silicon microstrip detectors that revolutionised high-precision tracking and vertexing in high-energy physics experiments”. At the end of the 1970s, the trio developed the first silicon-strip counters for particle physics using the NA11 and NA32 experiments at CERN. Gerhard Lutz sadly passed away aged 77 in April this year (see “Gerhard Lutz 1939–2017”).
The 2017 Giuseppe and Vanna Cocconi Prize for an outstanding contribution to particle astrophysics and cosmology goes to Rainer Weiss of MIT and to Kip Thorne and Barry Barish of Caltech, “for their pioneering and leading roles in the LIGO observatory that led to the direct detection of gravitational waves, opening a new window to the universe”. LIGO has recently detected its third gravitational-wave event, and a global effort is mounting to build further such observatories (see “ESA gives green light for LISA”).
Theorist Simon Caron-Huot of McGill University has won the 2017 Gribov Medal for outstanding work by a young physicist in theoretical particle physics and/or field theory, “for his groundbreaking contributions to the understanding of the analytic structure of scattering amplitudes and their relation to Wilson loops”. The Young Experimental Physicist Prize for outstanding work by a young physicist, meanwhile, was won by Xin Qian of Brookhaven National Laboratory, “for his key contributions to the Daya Bay Reactor neutrino experiment that led to the measurement of the neutrino mixing angle θ13”.
The 2017 Outreach Prize was awarded to Michael Hoch, who is a member of the CMS collaboration, “for initiatives highlighting the conceptual and physical beauty of high-energy physics, and the inspirational qualities that are common to both art and science”. Finally, the 2017 Special Prize of the EPS high-energy and particle-physics division was awarded to René Brun of CERN, “for his outstanding and original contributions to the software tools for data management, detector simulation, and analysis that have shaped particle and high-energy physics experiments for many decades”. Brun pioneered the GEANT3 detector-simulation system, co-ordinated the development of the PAW (Physics Analysis Workstation) platform, and in 1995 created the ROOT system while working for the NA49 heavy-ion experiment.
High recognition for CERN Director-General
On 20 June, CERN Director-General Fabiola Gianotti was received as a Foreign Associate of the French Academy of Sciences in Paris. Established in 1666, the Academy has 262 members and 138 foreign associates. Also in June, she received an honorary doctorate from the University of Roma Tor Vergata and also the 2017 Tomassoni Prize from the University of Roma La Sapienza, “for the innumerable contributions to particle physics that led her to play a leading role in discovering the Higgs boson as spokesperson of the ATLAS experiment and in the orientation of current and future research as DG of CERN”. The prize money will be donated to the CERN & Society Foundation for educational programmes.
Two schools win beam time at CERN
On 13 June, CERN announced the winners of its 2017 Beamline for Schools competition. Selected from 180 team entries from 43 countries, totalling around 1500 high-school students, the winners were “Charging Cavaliers” from École secondaire catholique Père-René-de-Galinée in Cambridge, Canada, and “TCO-ASA” from the Liceo Scientifico Statale “T C Onesti” in Fermo, Italy. In September the teams will come to CERN to carry out their own experiments at a fully equipped CERN beamline. Charging Cavaliers, comprising 13 students, plans to search for elementary particles possessing fractional charge by observing their light emission in the same type of liquid scintillator as that used in the SNO+ experiment at SNOLAB, Canada. Team TCO-ASA, comprising eight students, has chosen to build a Cherenkov detector at its school and wishes to test it in a real particle beam.
The first Beamline for Schools competition was launched in 2014 on the occasion of CERN’s 60th anniversary. To date, winners from the Netherlands, Greece, Italy, South Africa, Poland and the UK have performed their experiments at CERN.
2017 GÉANT Community Awards
GÉANT is a fundamental element of Europe’s e-infrastructure, delivering a high-bandwidth and high-speed fibre-optic backbone for Europe’s national research and education centres. Since 2012, the GÉANT Community Awards have honoured individuals who have contributed significant ideas, time and expertise to the development of the network. The 2017 awards were presented at the TNC17 networking conference in Linz, Austria.
Massimo Parovel of the Music Conservatory Giuseppe Tartini, Trieste, had the idea to enable performing artists to interact even if they are located thousands of kilometres apart, resulting in a low-latency audiovisual system called LOLA that is now being used for events and educational purposes. Husband-and-wife team Tomasz Wolniewicz and Maja Górecka-Wolniewicz of PSNC and Nicolaus Copernicus University shared an award for their work on the eduGAIN service infrastructure, the eduroam Configuration Assistant Tool and other activities. Finally, Hannah Short of CERN’s IT department was commended for making signficant contributions through her leadership of work in the REFEDS and AARC project communities on Sirtfi (Security Incident Response Trust Framework for Federated Identity), which enables incident response to be co-ordinated across federated organisations.
SESAME celebrates opening
On 16 May the SESAME light source in Jordan was officially opened by King Abdullah II, marking a new era of research in the region covering fields ranging from medicine and biology, through materials science, physics and chemistry to healthcare, the environment and archaeology.
An intergovernmental organisation, SESAME (Synchrotron-light for Experimental Science and Applications in the Middle East) is the first regional laboratory for the Middle East and neighbouring regions. It is based around a 42 m-diameter storage ring in which electrons generate intense beams of synchrotron light for diverse user experiments. First turns of the electrons took place in January, and SESAME’s initial research programme with three beamlines will be operational this year.
CERN has played a major role in the facility, notably through the European Commission-funded CESSAMag project, which provided the magnet system for SESAME’s main ring and brought CERN’s expertise in accelerator technology to the project.
The May ceremony also saw a changeover in SESAME’s organisation, with former CERN Director-General Rolf Heuer succeeding fellow former CERN Director-General Chris Llewellyn Smith as the new president of the SESAME Council. “SESAME truly embodies the spirit of scientific curiosity and collaboration that is the driving force of human progress,” said Fabiola Gianotti, Director-General of CERN, at the event. “CERN and SESAME have this in common: both were established to provide a centre of scientific excellence and to foster collaboration among neighbours.”
UK hosts third HL-LHC industry day
The third edition of the High Luminosity LHC (HL-LHC) Industry Day took place in Warrington, a few minutes away from Daresbury Laboratory in the UK, on 22–23 May. The two-day event, jointly organised by CERN and the Science and Technology Facilities Council (STFC), gathered some 200 participants from 17 European countries. Key engineers and physicists from CERN and STFC presented the technical challenges of the HL-LHC project to numerous company delegates attending the event. The face-to-face meetings arranged with the CERN engineers were also an excellent opportunity for companies to learn more about the key components of the HL-LHC upgrade and the upcoming calls for tenders.
The HL-LHC will allow the LHC to achieve instantaneous luminosities a factor five larger than its nominal value, and the project’s estimated CHF950 million cost will be realised within a constant CERN budget. The HL-LHC study phase started in 2010 and the commissioning phase will finish in 2026. The upgrade is crucial not only for the full exploitation of the LHC’s physics potential, but also to enable operation of the collider beyond 2025. More than 1.2 km of the present LHC plus associated technical infrastructure will be renewed – a challenge that can only be accomplished with the strong involvement of European industry. Since 2012, the HL-LHC has therefore organised events to connect CERN with potential industrial partners that can meet the specific technical challenges.
Accelerator experts meet in Copenhagen
The 8th International Particle Accelerator Conference (IPAC) took place in Copenhagen, Denmark, on 14–19 May and was attended by more than 1550 participants from 34 countries. Hosted by the European Spallation Source (ESS) and organised under the auspices of the European Physical Society (EPS) accelerator group and the International Union of Pure and Applied Physics, the event was also supported by the MAX-IV facility and Aarhus University.
Although accelerators were initially developed to understand the infinitesimal constituents of matter, they have evolved into sophisticated instruments for a wide range of fundamental and applied research. Today, particle accelerators serve society in numerous ways, ranging from medicine and energy to the arts and security. Advanced light sources are a case in point, following the steady improvement in their performance in terms of brilliance and temporal characteristics. MAX-IV and the ESS, which lie just across the Oresund bridge in Sweden, are two of the most powerful instruments available to life and material scientists, and are operating and under construction, respectively. Meanwhile, the most brilliant source of ultra-short flashes of X-rays – the European X-ray Free Electron Laser at DESY in Hamburg – has recently achieved first lasing and will soon be open to users (“Europe enters the extreme X-ray era”). Another X-ray free-electron laser, the SwissFEL at PSI, has just produced laser radiation for the first time in the soft X-ray regime and aims to achieve smaller wavelengths by the end of the year. New synchrotron light sources have also come into operation, such as the SOLARIS synchrotron in Poland, and major upgrades to the European Synchrotron Radiation Facility in France based on a new lattice concept are planned.
Particle physics remains one of the main drivers for new accelerator projects and for R&D in IPAC’s many fields. The big brother of all accelerators, CERN’s LHC, performed outstandingly well during 2016, exceeding nominal luminosity by almost 50% thanks to operations with more tightly spaced bunches and due to the higher brightness of the beams delivered by the LHC injectors. Mastering the effects of electron clouds and carrying out progressive “scrubbing” of the surfaces of the LHC beam screens have been key to this performance. Achieving nominal luminosity marks the completion of one of the most ambitious projects in science and bodes well for the High Luminosity LHC upgrade programme now under way. IPAC17 also heard the latest from experiments at CERN’s Antiproton Decelerator facility, including the trapping and subsequent spectroscopic measurements of antihydrogen atoms and the exciting studies that will still be carried out using the new ELENA facility there.
On the lepton machine front, the Super KEKB electron–positron collider at KEK in Tsukuba, Japan, was successfully commissioned with beam in 2016. The superconducting quadrupoles and correctors of the final focusing system and the BELLE II detector are being installed, and commissioning with beam is due to be completed in 2018 when first data are also expected. Concerning the quest for higher-energy circular and linear electron–positron colliders, the main accelerator technology choices for the Compact Linear Collider (CLIC) have recently been validated at CERN’s CTF3 test facility, and the gradient of CLIC’s two-beam acceleration principle has been established beyond 100 MV/m. There has also been impressive progress in the design of a very large high-luminosity circular electron–positron collider in the frame of the Future Circular Collider design study, while corresponding studies for a future hadron–hadron collider at CERN and similar studies are also under way in China.
Making progress at the high-intensity and high-energy frontiers demands continuous advances in accelerator technology, and superconductivity is vital for high-field magnets and high-gradient RF cavities for continuous-wavelength operation. Normal conducting RF structures operated at high frequency are also achieving new performance records, demonstrating accelerating gradients up to 120 MV/m, and this technology is attracting the attention of several laboratories keen to build compact free-electron lasers. In the field of novel accelerator concepts, a new scheme to produce very low-emittance muon beams based on the interaction between a 45 GeV positron beam and a thin target has been devised by researchers at INFN Frascati. Finally, with increasing attention to the energy efficiency of accelerators, major steps are being made in the domain of high-efficiency RF sources, where efficiencies of up to 85% were reported at this year’s IPAC event.
The Copenhagen conference saw 115 companies from 16 countries present their products as part of an industrial exhibition, which was complemented by lively panel discussions on industrial careers, intellectual property and other relevant issues. In total there were 45 invited and 51 contributed oral presentations and approximately 1400 posters, with the EPS accelerator group also awarding its 2017 prizes (CERN Courier April 2017 p38). The 9th IPAC will take place in Vancouver, Canada on 29 April– 4 May 2018.
LHC physics shines in Shanghai
The Large Hadron Collider Physics (LHCP) conference took place at Shanghai Jiao Tong University (SJTU) in China, on 15–20 May. One of the largest annual conferences in particle physics, the timing of LHCP2017 chimed with fresh experimental results from the ALICE, ATLAS, CMS and LHCb experiments based on 13 TeV LHC data recorded during 2015–2016. The conference saw many new results presented and also offered a broad overview of the scientific findings from Run 1, based on lower-energy data.
One of the main themes of the conference was the interplay between different results from various experiments, in particular those at the LHC, and the need to continue to work closely with the theory community. One such example concerns measurements of rare B-meson decays and in particular the decay B0 → K*l+l–, which is sensitive to new physics and could probe the presence of new particles through the study of the B0 helicity structure. The LHCb collaboration has found several discrepancies with Standard Model (SM) expectations, including a more than three standard-deviation discrepancy in the angular distributions of this B0 decay. New results presented by ATLAS and CMS have created further tension in the situation (see diagram), and more data from LHC Run 2 and continued theoretical developments will be critical in understanding these decays.
An exciting result from the ALICE experiment showed a surprising enhancement of strange-baryon production in proton–proton collisions (CERN Courier June 2017 p10). In nucleus–nucleus collisions, this enhancement is interpreted as a signature of the formation of a quark–gluon plasma (QGP) – the extreme state that characterised the early universe before the appearance of hadrons. The first observation of strangeness enhancement in high-multiplicity proton–proton collisions hints that the QGP is also formed in collisions of smaller systems and opens new directions for the study of this primordial state of matter.
From the Higgs sector, CMS reported an observation of Higgs decays to two particles with a significance of 4.9 standard deviations compared to SM backgrounds. Differential cross-sections for Higgs decays to two Z bosons, which test properties of the Higgs such as its spin and parity and also act as a probe of perturbative QCD, were shown by ATLAS. Throughout the conference, it was clear that precision studies of the Higgs sector are a critical element in elucidating the nature of the Higgs boson itself, as well as understanding electroweak symmetry breaking and searching for physics beyond the SM.
In addition to these highlights, a broad spectra of results were presented. These ranged from precision studies of the SM, such as new theoretical developments in electroweak production, to numerous new search results, such as searches for low-mass dark-sector mediators from the CMS experiment and searches for supersymmetry in very high-multiplicity jet events for ATLAS. The conclusion from the conference was clear: we have learnt a tremendous amount from the Run 2 LHC data but are left with many open questions. We therefore eagerly await the newest data from the LHC to help further dissect the SM, cast light on the nature of the Higgs, or to find an entirely new particle.
Exploring axions and WIMPs in Greece
On 15–19 May, the historic Greek city of Thessaloniki hosted the 13th annual edition of the Patras Workshop on Axions, WIMPs and WISPs. Since the first meeting in 2005, the event has evolved into an important annual conference of the astroparticle community, addressing questions related to dark matter and dark energy both from the experiment and theory sides. Related topics from neutrino or astrophysics complement the agenda. An all-time high of more than 120 scientists attended the workshop this year, indicating the ever-growing interest in the quest for dark matter and especially for axions.
As well-established dark-matter candidates, along with weakly interacting massive particles (WIMPs), axions and axion-like particles (ALPs) are a central topic of the workshop. A large number of ongoing, planned and proposed experiments cover the full axion mass range with a good chance of detection. The most stringent experimental bounds on axion-to-photon couplings still come from “helioscopes” such as the CAST experiment at CERN, which use large magnets to convert axions produced in the Sun to detectable X-ray photons. New proposals discussed at the workshop aim at improving the sensitivity of experiments but also at extending their reach to dark-matter axions and dark-energy candidates such as chameleons (scalar particles that change their coupling strength in response to the local matter density). Dedicated chameleon searches were presented, exploiting both their coupling to photons and to matter, the latter using a novel opto-mechanical detector.
Dark-matter axions are the target of “haloscopes”, which search for relic axions in the galactic halo using ultra-cold resonant microwave cavities immersed in a magnetic field. Various techniques to reach higher frequencies and to move the axion-mass coverage to the meV region are under study, and first results on axion masses up to around 24 μeV were reported by the HAYSTAC collaboration. Other projects aim at reaching even higher masses: multi-vane cavities, distributed Bragg reflectors, photonic band-gap resonators and multi-layered dielectric discs. These experiments employ cutting-edge superconducting technology and use amplifiers developed for quantum-computing research. Superconducting cavities that can achieve quality factors as high as 106 and ultra-high field magnets (up to 25 T) are also being developed at IBS/CAPP in Korea.
On the theory side, talks ranged from axions in string theory to estimates of the axion mass using the tools of lattice QCD. Several contributions focused on the observed anomalous transparency of the universe for high-energy photons, which might be explained by processes involving ultra-light ALPs with masses in the neV region or below. Others discussed whether the current density of dark-matter axions might differ from the homogeneous canonical picture due to the presence of axion condensates, caustics and mini-clusters.
A plethora of experiments aim at the direct detection of feeble WIMP-induced nuclear recoils. WIMPs are one of the prime candidates for cold dark matter because they arise naturally in various theories beyond the Standard Model of particle physics. The search strategy differs slightly for low- and high-mass WIMPs, with the transition taking place at around 5 GeV/c2, but all efforts rely on ultra-low backgrounds and low thresholds. The Patras event saw detailed reports from almost a dozen running and upcoming projects – a highlight being the first public presentation of new results from the XENON1T dark-matter experiment, which has set the most stringent limits on WIMP-nucleon scattering above WIMP masses of around 10 GeV/c2 (see “XENON1T releases first data”). WIMP physics can also be probed indirectly, for instance by the Fermi telescope, and by colliders such as the LHC. It is now clear that, while the simplest WIMP models are under some pressure given the non-detection so far, plenty of well-motivated parameter space remains.
There are also a number of promising fixed-target experiments looking for portals from the dark sector to the Standard Model, such as dark photons, and other subtle experiments to study the low-energy, high-intensity frontier. In this frame, the community can look forward to developments with CERN’s “Physics Beyond Colliders” initiative (CERN Courier November 2016 p28) and the US “Cosmic Vision” initiative.
Berlin meeting weighs up post-LHC machine
From 29 May to 2 June, more than 500 participants attended the 3rd Future Circular Collider (FCC) collaboration week in Berlin, Germany. The meeting heralds a new phase for the FCC collaboration, which will now start preparing a design report and cost estimates for all collider options, to be delivered by the end of 2018. The vibrant and global R&D programme of FCC paves the way for future energy and intensity-frontier colliders that could replace the LHC by the mid-2030s. Impressive progress is being made across all domains of the FCC study, and the large number of young researchers involved is highly promising for the future of the field.
In view of the long lead times of major projects in high-energy physics, the FCC study is exploring several possible options for post-LHC circular colliders. For CERN to retain its pole position in accelerator-based particle physics – as said by CERN Director-General Fabiola Gianotti in her opening address – the laboratory “must continue to play a leading role in global efforts to develop technologies and design future colliders that could succeed the LHC in the medium-to-long term”. The formidable feat of creating the next LHC – a machine that offers significant increases in energy and luminosity compared with today’s machines – also requires new levels of global co-operation.
The FCC study envisions an accelerator complex that would offer a rich physics programme far into the 21st century. Specifically, the study explores concrete plans for an energy-frontier hadron collider (FCC-hh) and a luminosity-frontier lepton collider (FCC-ee) housed in a new 100 km-circumference tunnel in the Geneva region. The study also includes an electron–hadron collider (FCC-he) and examines the option of a high-energy upgrade of the LHC (HE-LHC) that could double the present energy reach. FCC week 2017 reviewed progress across the different study domains. Revised layouts of accelerators and detectors were reviewed both for the proton and the lepton machines, and a new reference layout based on a 97.75 km-circumference tunnel was presented. The many rich physics opportunities opened by FCC, along with the possible synergies and complementarities of the different machines, were also discussed in great depth.
The collider scenarios explored in the FCC study pose a number of technological challenges. The FCC Week 2017 witnessed a growing worldwide eagerness from the scientific and engineering communities, with participants discussing technological and manufacturing breakthroughs that can help to meet the FCC’s performance and cost goals. As the CERN director for accelerators and technology, Frédérick Bordry, remarked: “Designing and building a post-LHC accelerator should be based on the use of breakthrough technologies to provide the beam energy, intensity and brightness that are required for a future discovery machine. The ongoing FCC R&D programme is a natural extension of the High-Luminosity LHC activities and it ensures the efficient use of past investments.”
The key to reaching the highest energies is the development of new superconducting magnets able to reach dipole fields of 16 T, roughly twice that of the LHC. Significant advances in superconductors, superconducting RF technologies and RF power sources are needed, as is a new beam vacuum system to meet the challenges of going to higher energies. Good progress towards the CDR has been made for other systems, including cryogenics and the supply of electricity.
FCC Week 2018 will take place in Amsterdam and will be the final meeting before the presentation of the Conceptual Design Report scheduled for the end of 2018. By then, results from the second round of the LHC should provide another crucial input needed by the global high-energy physics community to decide on the next generation of colliders.
On 16 May, 12 European astronauts visited CERN on a trip organised by Claude Nicollier and Samuel Ting, taking in the AMS control centre.
On 8 June, Janis Reirs, minister for welfare, Republic of Latvia (second from left), visited CERN, taking a tour of the Synchrocyclotron and CMS.
President of the Republic of Mauritius, Dr Ameenah Gurib-Fakim, visited CERN in the morning of Friday 16 June and toured the Synchrocyclotron and the ATLAS experiment before signing the guestbook. She is pictured with (centre) Markus Nordberg, head of resources development at CERN, at the IdeaSquare facility.
Bidya Devi Bhandari, president of the Federal Democratic Republic of Nepal, came to CERN on 16 June. She visited the Synchrocyclotron and the ATLAS control room,and is pictured here with former ATLAS spokesperson Dave Charlton.