Mar 17, 2017
Faces & Places
New director for Jefferson Lab
Accelerator physicist Stuart Henderson, 53, has been named the fourth director of the Thomas Jefferson National Accelerator Facility in Virginia, US. Currently director of the Advanced Photon Source upgrade project at Argonne National Laboratory, he will start his new role on 3 April. Prior to joining Argonne, Henderson was associate laboratory director for accelerators at Fermilab and before that he spent almost a decade at Oak Ridge National Laboratory’s Spallation Neutron Source (SNS), where he led the transition to successful user operations at megawatt-beam power levels.
Henderson replaces Hugh Montgomery, who came to Jefferson Lab as director in 2008 from Fermilab and will continue his association with the facility as director emeritus. Jefferson Lab has enjoyed significant growth in recent years, which includes the $338 million 12 GeV Upgrade Project and construction of a $70 million addition to the lab’s engineering and design facilities. “I’m thrilled to be taking the helm of Jefferson Lab, particularly at this time of tremendous opportunity and potential,” says Henderson. “Jefferson Lab plays a very special role in furthering the Department of Energy mission, both through its operation of a world-class nuclear-physics research facility, and through its world-renowned technology capabilities.”
Rüdiger Voss next president of EPS
Former CERN staff member Rüdiger Voss has been appointed president of the European Physical Society (EPS), beginning 1 April and effective for two years. Established in 1968, the EPS represents 42 national physical societies, which in turn represent more than 120,000 members. It has a similar number of associate members – mostly major research institutions such at CERN – and about 3500 individual members.
Voss, who completed a PhD in deep inelastic muon–nucleon scattering at CERNʼs SPS in 1982, joined CERN as a research physicist in 1987. Following various group-leader positions in the experimental-physics division, in 2009 he became a senior adviser for international relations and then head of the unit from 2013 to 2015.
Among his many goals as EPS president, Voss wants to strengthen global co-operation and networks and raise the voice of science in the face of Europe’s changing political landscape, which he says poses severe threats to cross-border collaboration, the mobility of students and researchers, and equal access to European funding and infrastructures. “The EPS, representing a scientific discipline with a highly developed culture of international collaboration, has a special responsibility to voice a strong opinion in this discussion,” he says. “This concern is not unique to physics, and needs to be addressed by the scientific community at large.” (See “European organisations uphold scientific values” in News.)
Neutrino trio wins 2016 Pontecorvo Prize
The Joint Institute for Nuclear Research (JINR) in Dubna, Russia, has selected the winners of the Bruno Pontecorvo Prize, which is awarded each year for significant advances in elementary particle physics. The 2016 recipients, who are recognised for their outstanding contributions to the study of neutrino oscillations and to the measurement of the θ13 mixing angle using the Daya Bay, RENO and T2K experiments, are: Yifang Wang of the Institute of High Energy Physics in Beijing, China; Soo-Bong Kim of Seoul National University, South Korea; and Koichiro Nishikawa of the KEK Laboratory in Tsukuba, Japan.
Wang pioneered the Daya Bay neutrino oscillation experiment in China, while Kim is spokesperson for the Reactor Experiment for Neutrino Oscillation (RENO) in South Korea and Nishikawa is the founding spokesperson of the T2K and K2K experiments in Japan. The 2016 prizewinners will receive the award at a ceremony in September.
Bruno Pontecorvo died in 1993 at Dubna, and the prize was instituted in his memory two years afterwards. It was Pontecorvo who in 1957 suggested that neutrinos might change from one type to another. The experimental discovery of neutrino oscillation half a century later by Super-Kamiokande and the Sudbury Neutrino Observatory was recognised with the 2015 Nobel Prize for Physics.
EPS announces accelerator prizes
The European Physical Society (EPS) accelerator group has announced the winners of the 2017 accelerator prizes, to be presented on 18 May during the International Particle Accelerator Conference (IPAC17) in Copenhagen.
Lyn Evans of CERN receives the Rolf Wideröe Prize for outstanding work in the accelerator field. He is rewarded for his many major accomplishments in the field of accelerator design, construction and operation, in particular his contributions to the SPS and his leadership of the design and construction of the LHC. Research at the SPS led to the discovery of the W and Z bosons, while the LHC uncovered the Higgs boson in 2012.
The Gersch Budker Prize for a recent significant, original contribution to the accelerator field goes to Pantaleo Raimondi of the ESRF in Grenoble in recognition of his invention of a new storage-ring lattice called the “hybrid multi-bend achromat”. The novel design will reduce the emittance of the ESRF light source by a factor of 30 and has also been adopted as the basis for the design of several other next-generation light sources.
Finally, the Frank Sacherer Prize recognising an individual in the early part of his or her career goes to Anna Grassellino of Fermilab, for her major impact on the field of superconducting RF technology. The techniques of nitrogen doping and “nitrogen infusion” developed by Grassellino have already been applied to accelerator projects and have the potential to significantly reduce the cryogenic load and improve the energy efficiency of superconducting linacs.
AAAS honours Kurt Gottfried
Kurt Gottfried, professor emeritus of physics at Cornell University and a renowned authority on nuclear-arms control, has been awarded the 2016 Scientific Freedom and Responsibility Award from the American Association for the Advancement of Science (AAAS). Gottfried, an expert in quantum theory who was a visiting scientist at CERN in the 1960s, was honoured “for his long and distinguished career as a ‘civic scientist’, through his advocacy for arms control, human rights and integrity in the use of science in public policymaking”.
Julius Wess Award for detector work
Robert Klanner of the University of Hamburg and DESY has been nominated for the 2016 Julius Wess Award for outstanding achievements in elementary particle and astroparticle physics. The award, established in 2008 by the KIT Elementary Particle and Astroparticle Physics Center, recognises Klanner’s fundamental contributions to the development of silicon-microstrip detectors, in particular for achieving the resolution required to reconstruct secondary vertices from the decay of heavy-flavoured hadrons. In the early 1980s, together with Gerhard Lutz and the late Josef Kemmer, Klanner used planar processes to build a silicon-strip detector, and in doing so initiated the culture of flavour-tagging in particle physics.
Highlights from Quark Matter 2017
The 26th Quark Matter conference, devoted to ultra-relativistic nucleus–nucleus collisions, was held in Chicago on 5–11 February. Following a pre-conference student day that attracted nearly 400 young scientists, the main event had more than 700 registered participants. Overviews of the most recent results from experiments, spanning the entire energy range from the SIS 100 accelerator at GSI Darmstadt to the highest energies at CERN’s LHC, were followed by almost 200 parallel presentations, 30 plenary talks and a session with more than 300 posters.
Nucleus–nucleus collisions have long been known to display characteristic signatures of collectivity, and this was one of the main themes at the Chicago event. Collectivity is typically quantified in terms of flow coefficients, vn, where n corresponds to a particular harmonic in the azimuthal distributions of produced particles. Since the first LHC proton–lead run in 2013, it has been known that sizeable vn are also observed in proton–lead collisions and even in detailed analyses of high-multiplicity proton–proton collisions.
At this year’s conference, the LHC’s ALICE experiment presented novel results on identified particle flow. The data show that φ mesons flow like pions and kaons, that heavy-flavoured D mesons display sizable collectivity above 10 GeV and that even J/ψ mesons partake in collective motion in lead–lead collisions. Both ALICE and CMS also presented novel analyses of the correlations between different flow coefficients, while CMS quantified the differences between D-meson flow and light-hadron flow for v2 and v3, which inform us about differences in the interactions of light partons and heavy quarks with the hot medium. ATLAS showed new results on heavy-flavour flow in proton–lead collisions. These results were complemented by more detailed analyses from RHIC in the US, revealing the mass ordering of flow coefficients and heavy-flavour flow measured by the STAR experiment, and small-system collectivity including proton–gold, deuteron–gold and helium–gold collisions measured by PHENIX.
Theory-overview talks focused on the validity of relativistic fluid dynamic simulations supplemented with realistic initial conditions and properties of the hot-partonic and the hadronic phases. The extent to which the simulations can account for collectivity in soft-particle production, and in particular how global Bayesian analyses that are novel for this field can be used to zoom in on fundamental properties of the quark–gluon plasma, was the subject of many parallel talks. In addition to details of these analyses, the Chicago conference discussed the new challenges for theory and experimental analyses that arise from characterising and understanding collectivity in smaller systems.
Another highlight of the event was progress on the topic of hard probes. Since the first experiments at RHIC, it has been known that the yield of high-pT final-state hadrons is suppressed or “quenched” by a factor of around five in central heavy-ion collisions. Measurements at the LHC have extended the dynamic range of these measurements and have gradually made a whole new set of jet-based probes available. The last two years have also seen a strong push towards analysing jet substructures with modern analysis techniques, and Quark Matter 2017 featured the first detailed public discussion of such developments. For instance, researchers are exploring novel opportunities for characterising jet-medium interactions and medium-induced parton splittings based on so-called “groomed” jet variables, such as the groomed zg distributions measured by CMS and STAR or jet-mass measurements presented by ALICE.
Apart from these new observables, a number of well-known measurements have been repeated using the much larger data samples of LHC Run 2 to improve the measured kinematic ranges and statistical accuracy. In particular, ATLAS showed nuclear modification factors for jets that reveal a factor of two suppression for jets with a transverse energy up to 1 TeV, while both ATLAS and CMS presented much improved measurements of the energy imbalance for photon jets and CMS presented Z-boson-jet pairs, which provide precise information about the probability distribution for energy loss. An exciting future perspective is that a detailed analysis of the softening of jet fragmentation may provide experimental access to the microscopic mechanisms underlying equilibration processes in the hot and dense medium.
There were many further highlights at Quark Matter 2017. Results ranged from the ATLAS measurement of dijet photoproduction in ultra-peripheral collisions, which may yield novel constraints on the nuclear dependence of parton distribution functions, to new precision measurements of the sequential suppression of bottomonium states at CMS. New results from RHIC also included a first measurement of the charmed Λc baryon by the STAR experiment, which provides a new way to test hadronisation models. We also saw the first measurements of net particle moments by ALICE, which provide a critical reference for fluctuation measurements in the RHIC beam-energy scan.
Space was also given to discussions of the physics plans for the LHC heavy-ion programme in Run 3 and beyond, as well as the planning for the new “sPHENIX” detector at RHIC that has recently passed an important review and is expected to take first beam in 2022. Participants now have 15 months to consider the presented results and make progress before the next Quark Matter meeting in Venice in May 2018.
Slush brings scientists and entrepreneurs closer
With an astonishing 17,500 attendees, one million livestream viewers and thousands of participating start-up companies and venture capitalists, Slush is Europe’s leading entrepreneurship event. Among accredited business founders and investors, CERN was invited to give a keynote speech at the 2016 edition of the annual event, held in Helsinki, Finland, at the start of December. With Slush aiming to aid the next generation of world-conquering companies and CERN aiming to find answers to fundamental questions about the universe, you might wonder what these two organisations have in common.
Although there has traditionally existed a gap between science and entrepreneurship, both communities have started to realise that the benefits of co-operating are reciprocal. One of the ways innovations and know-how can be applied more generally is through starting new ventures, and CERN is committed to building a culture of entrepreneurship among its scientists and engineers to help maximise the impact of CERN on society. Vice versa, new initiatives such as Slush Science Track have brought academic research into the spotlight by gathering top-quality research and offering a €100,000 prize for the best basic research presented. Slush underpins its initiative by remarking that “all inventions come from science, and that today’s findings will lead to products years later”.
Antwerp workshop sets reference
At the beginning of November, at the Resummation, Evolution, Factorization (REF) meeting, about 40, mostly young, scientists met in Antwerp in Belgium to discuss limitations in present calculations and simulations concerned with Standard Model processes. These limitations, which concern the physics programme both at the LHC and at future lepton–hadron colliders, come from neglecting the transverse momenta that arise in the QCD evolution of initial-state partons during collisions. Very small transverse momenta shed light on the intrinsic hadronic structure, while large transverse momenta can change the kinematics of processes significantly. In the usual collinear evolution and parton-distribution functions, these transverse momenta are not considered explicitly.
One of the highlights of the workshop was the determination of the very first complete transverse-momentum-dependent parton distributions, which are valid over the full range of momentum accessible at the LHC. Progress has been reported in the region of very small longitudinal momenta, where saturation effects typically appear. New tools for transverse-momentum-dependent parton distributions (TMDs) were reported, including a complete library containing all publicly available TMDs and visualisation tools.
The REF workshop series, which started in 2014, is unique because it addresses questions from high-energy particle collisions together with issues coming from the non-perturbative structure of hadrons. These are very new and exciting attempts to describe in a uniform manner the low- and high-energy behaviour of particle collisions, which has much impact on the precision of LHC predictions. Although still a small community, the range of applications of TMD approaches cover the most interesting and important regions where resummation to all orders in perturbation theory is relevant, and which is the major focus of new and challenging Standard Model measurements at the LHC. The next edition of the REF workshop will be held in Madrid, Spain, from 13 to 17 November 2017.
Celebrating a decade of high-end computer algebra
Precision calculations of scattering processes at high-energy colliders such as the LHC rely on advances in computer algebra to process the enormous number of higher-loop Feynman integrals. For the past 10 years, the DESY theory group at Zeuthen has collaborated in this field with mathematicians from the Research Institute of Symbolic Computation (RISC) at Johannes Kepler University (JKU) in Linz. During the collaboration, various symbolic summation and integration packages, as well as those for related special functions, have been created. These are publically available and offer broad automation of analytic Feynman integral calculations for two- and three-loop integrals.
To mark the 10th anniversary of this successful partnership, a one-day workshop took place at Hagenberg Castle in Austria on 7 February, during which representatives of DESY and JKU extended their collaboration agreement for a further five years. The directors of research at Wolfram Research and MapleSoft also contributed reports on the latest versions of Mathematica and Maple, while special lectures were delivered about summation theory, elliptic solutions, precision calculations for the LHC and new developments in q-series.
Director-general of the United Nations Office, Michael Møller, visited CERN on 6 February with other heads of United Nations agencies, during which they toured the ATLAS cavern and visited the LHC tunnel.
Marie-Christine Marghem, Belgian minister for energy, environment and sustainable development, came to CERN on 20 February. Following a tour of CMS, she signed the guestbook with (left to right): CERN director for accelerators and technology Frédérick Bordry, Belgian ambassador to the UN Geert Muylle, CERN Director-General Fabiola Gianotti, and CERN director for research and computing Eckhard Elsen.
Ofir Akunis, minister of science, technology and space in Israel, visited CERN on 22 February, during which he toured ATLAS with former experiment spokesperson Peter Jenni (left).
Edgars Rinkevičs, minister of foreign affairs for the Republic of Latvia, came to CERN on 27 February and visited the CMS experiment. He signed the guestbook with CERN director for international relations Charlotte Warakaulle and non-Member State adviser Christoph Schaefer.