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WELCOME V OLUME 5 7 N UMBER 9 N OVEMBER 2 0 1 7 CERN Courier – digital edition Welcome to the digital edition of the November 2017 issue of CERN Courier.

Rarely has such a short paper sparked such a massive experimental campaign as Steven Weinberg’s 50 year-old “Model of Leptons”. CERN, along with SLAC in the US and others, has been at the centre of the action in verifying the model’s predictions: it took Gargamelle to unearth neutral currents, the Super Proton Synchrotron to produce the W and Z bosons, the Large Electron–Positron collider to measure their properties in detail, and the Large Hadron Collider to flush out the Higgs boson. Unifying the electromagnetic Iconic physics and weak interactions, Weinberg’s iconic 2.5 page-long and relatively straightforward manuscript brought a much needed moment of clarity to the field. But today, with all its bosons bagged, Weinberg says that the electroweak Standard Model has become a victim of its own success, with no obvious way to break through to a more fundamental picture. This month we also celebrate 60 years of the Particle Data Group, whose Review of Particle Physics has been at the side of physicists throughout the Standard Model’s remarkable evolution.

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X-FACTOR PILING UP COMPUTING Xenon beams in Particle Data Group SPS shine light on tracks 60 years of WITH INDUSTRY EDITOR: MATTHEW CHALMERS, CERN gamma factory progress in the fi eld CERN openlab prepares for DIGITAL EDITION CREATED BY DESIGN STUDIO/IOP PUBLISHING, UK p7 p19 the HL-LHC era p5

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It’s Time for a Covering current developments in high-energy physics and related fi elds worldwide CERN Courier is distributed to member-state governments, institutes and laboratories affi liated with CERN, and to their personnel. It is published monthly, except for CERNCOURIER New Generation January and August. The views expressed are not necessarily those of the CERN management.

Editor Matthew Chalmers V o l u m e 5 7 N u m b e r 9 N o V e m b e r 2 0 1 7 Books editor Virginia Greco CERN, 1211 Geneva 23, Switzerland of Power Solutions! E-mail cern[email protected] Fax +41 (0) 22 76 69070 5 V i E W p O i n t Web cerncourier.com Advisory board Peter Jenni, Christine Sutton, Claude Amsler, 7 n E W s Philippe Bloch, Roger Forty FOR RESISTIVE AND Xenon beams light path to gamma factory CLEAR prospects Laboratory correspondents: • • SUPERCONDUCTING MAGNETS Argonne National Laboratory (US) Tom LeCompte for accelerator research China neutron source sees fi rst beam Brookhaven National Laboratory (US) Achim Franz • • Cornell University (US) D G Cassel UK neutrino investment steps up • Fastest spinning fl uid clocked DESY Laboratory (Germany) Till Mundzeck by RHIC LHCb digs deeper into lepton-fl avour universality EMFCSC (Italy) Anna Cavallini • • Enrico Fermi Centre (Italy) Guido Piragino CMS observes top quarks in proton–nucleus collisions ATLAS Fermi National Accelerator Laboratory (US) Katie Yurkewicz • Forschungszentrum Jülich (Germany) Markus Buescher experiment makes precision measurement of top-quark mass GSI Darmstadt (Germany) I Peter • IHEP, Beijing (China) Lijun Guo ALICE studies possible light tetraquark IHEP, Serpukhov (Russia) Yu Ryabov INFN (Italy) Antonella Varaschin Jefferson Laboratory (US) Kandice Carter 15 s CiEnCEWatCh CT-BOX JINR Dubna (Russia) B Starchenko All-In-One Current Measurement and Calibration System KEK National Laboratory (Japan) Saeko Okada Lawrence Berkeley Laboratory (US) Spencer Klein 17 a s t r O W a t C h Up to ±1.000 A, 1 ppm/K TC, 100 ksps Data-Logger and Oscilloscope Los Alamos National Laboratory (US) Rajan Gupta NCSL (US) Ken Kingery CT-Viewer software included with Ethernet, Serial and USB Nikhef (Netherlands) Robert Fleischer F E a t u r E s Novosibirsk Institute (Russia) S Eidelman Orsay Laboratory (France) Anne-Marie Lutz 19 The physicist’s guide to the universe PSI Laboratory (Switzerland) P-R Kettle Saclay Laboratory (France) Elisabeth Locci Sometimes referred to as the bible of particle physics, during the last EASY-DRIVER Science and Technology Facilities Council (UK) Jane Binks SLAC National Accelerator Laboratory (US) Melinda Baker 60 years the Review of Particle Physics has become the number-one ±5 A and ±10 A / ±20 V Bipolar Power Supply Series TRIUMF Laboratory (Canada) Marcello Pavan reference in the fi eld, detailing more than 38,000 measurements. Full-Bipolar operation, Digital Control Loop, Ethernet Connectivity Produced for CERN by IOP Publishing Ltd Device supported by Visual Easy-Driver software IOP Publishing Ltd, Temple Circus, Temple Way, 25 Birth of a symmetry Bristol BS1 6HG, UK Tel +44 (0)117 929 7481 Half a century ago, Weinberg published a paper that unifi ed the Publisher Susan Curtis electromagnetic and weak interactions and revolutionised our FAST-PS-M Production editor Lisa Gibson understanding of the fundamental forces. Digital Monopolar Power Supplies - up to 100 A Technical illustrator Alison Tovey Group advertising manager Chris Thomas High-Precision Monopolar Power Converters with Gigabit Ethernet Advertisement production Katie Graham 31 Model physicist Marketing & Circulation Angela Gage Embedded Linux OS, device supported by Visual PS software Steven Weinberg talks to CERN Courier Head of B2B & Marketing Jo Allen Art director Andrew Giaquinto about his seminal 1967 work and discusses where next for particle physics following the Advertising FAST-PS Tel +44 (0)117 930 1026 (for UK/Europe display advertising) discovery of the Higgs boson. Digital Bipolar Power Supplies - up to ±30 A and ±80 V or +44 (0)117 930 1164 (for recruitment advertising); E-mail: [email protected]; fax +44 (0)117 930 1178 Full-Bipolar, Digital Control Loop, High-Bandwidth, 10/100/1000 Ethernet Embedded Linux OS, device supported by Visual PS software General distribution Courrier Adressage, CERN, 1211 Geneva 23, Switzerland a C E s L a C E s E-mail: [email protected] 37 F & p In certain countries, to request copies or to make address changes, contact: China Ya'ou Jiang, Institute of High Energy Physics, PO Box 918, Beijing 100049, People’s Republic of China 45 r E C r u i t M E n t E-mail: [email protected] FAST-PS-1K5 Germany Antje Brandes, DESY, Notkestr. 85, 22607 Hamburg, Germany Digital Bipolar Power Supplies - up to ±100 A and ±100 V E-mail: [email protected] 48 B O O k s h E L F UK Sian Giles, Science and Technology Facilities Council, Polaris House, 1.500 W, Paralleling via SFP/SFP+, 1 ppm/K TC, 10/100/1000 Ethernet North Star Avenue, Swindon, SN2 1SZ Embedded Linux OS, device supported by Visual PS software E-mail: [email protected] 50 a r C h i V E US/Canada Published by Cern Courier, 6N246 Willow Drive, St Charles, IL 60175, US. Periodical postage paid in St Charles, IL, US Fax 630 377 1569. E-mail: [email protected] POSTMASTER: send address changes to: Creative Mailing Services, PO Box 1147, NGPS St Charles, IL 60174, US

High-Stability 10-kW Power Supply - 200 A / 50 V Published by European Organization for Nuclear Research, CERN, I NTERNATIONAL J OURNAL OF H IGH -E NERGY P HYSICS Digital Control Loop, Paralleling via SFP/SFP+, 10/100/1000 Ethernet 1211 Geneva 23, Switzerland CERNCOURIER Tel +41 (0) 22 767 61 11. Telefax +41 (0) 22 767 65 55 V OLUME 5 7 N UMBER 9 N OVEMBER 2 0 1 7 Embedded Linux OS, device supported by Visual PS software Printed by Warners (Midlands) plc, Bourne, Lincolnshire, UK

© 2017 CERN ISSN 0304-288X Iconic physics

X-FACTOR PILING UP COMPUTING A copy of Weinberg’s 1967 paper photographed in the CERN Xenon beams in Particle Data Group On the cover: SPS shine light on tracks 60 years of WITH INDUSTRY gamma factory progress in the fi eld CERN openlab prepares for p7 p19 the HL-LHC era p5 theory department. (Image credit: M Brice & J Ordan/CERN.)

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European Chamber Manufacturer Viewpoint Facing up to the exabyte era CERN openlab works with industry to tackle the ICT challenges of the high-luminosity LHC.

CERN openlab, which was established by the CERN IT department in 2001, is a public–private partnership that enables CERN to collaborate

S Bennett/ CERN with ICT companies to meet the demands of particle-physics research. Since the start of this year, CERN openlab has carried out an in-depth consultation to identify the main ICT challenges faced by the LHC research community over the coming years. Based on our findings, we published a white paper in September on future ICT challenges in scientific research. The paper identifies 16 ICT challenge areas that need to be tackled in collaboration with industry, and these have been grouped into four overarching R&D topics. The first focuses on data-centre technologies to ensure that: data-centre architectures are flexible and cost effective; cloud-computing resources can be used in a scalable, hybrid manner; new technologies An operator in the CERN By Alberto Di Meglio for solving storage-capacity issues are thoroughly data centre. The HL-LHC investigated; and long-term data-storage systems will demand 50–100 times The high-luminosity Large Hadron Collider are reliable and economically viable. The second more computing capacity (HL-LHC) will dramatically increase the rate of major R&D topic relates to the modernisation of than the LHC, as highlighted particle collisions compared with today’s machine, code, so that the maximum performance can be in a CERN openlab white boosting the potential for discoveries. In addition to achieved on the new hardware platforms available. paper published in extensive work on CERN’s accelerator complex and The third R&D topic focuses on machine learning, September. the LHC detectors, this second phase in the LHC’s in particular its potentially large role in monitoring High Precision UHV life will generate unprecedented data challenges. the accelerator chain and optimising the use of The increased rate of collisions makes the task of ICT resources. reconstructing events (piecing together the underlying The fourth R&D topic in the white paper identifies Chambers Delivered On Time collisions from millions of electrical signals read out ICT challenges that are common across research by the LHC detectors) significantly more complex. At disciplines. With ever more research fields such as the same time, the LHC experiments are planning to astrophysics and biomedicine adopting big-data employ more flexible trigger systems that can collect methodologies, it is vital that we share tools and Customise & Build Your Own Vacuum Chamber - a greater number of events. These factors will drive a learn from one another – in particular to ensure that Use Our Online Chamber Builder™ Service huge increase in computing needs for the start of the leading ICT companies are producing solutions that Free HL-LHC era in around 2026. Using current software, meet our common needs. • Highly skilled in-house technicians hardware and analysis techniques, the required In summary, CERN openlab has identified ICT computing capacity is roughly 50–100 times higher challenges that must be tackled over the coming ® • 100% quality Faroarm inspection than today, with data storage alone expected to enter years to ensure that physicists worldwide can get the 18 • Optional bake out with RGA the exabyte (10 bytes) regime. most from CERN’s infrastructure and experiments. It is reasonable to expect that technology In addition, the white paper demonstrates the • 316LN flanges & materials in stock improvements over the next seven to 10 years emergence of new technology paradigms, from will yield an improvement of around a factor 10 pervasive ultra-fast networks of smart sensors in • Unique Hydra~Cool™ water cooling technology - in both processing and storage capabilities for no the “internet of things”, to machine learning and “smart everything” paradigms. These technologies unrivalled performance, low cost extra cost. While this will go some way to address the HL-LHC’s requirements, it will still leave a could revolutionise the way big science is done, • Contact us for a chamber enquiry today! Alberto Di Meglio significant deficit. With budgets unlikely to increase, particularly in terms of data analysis and the control is head of CERN it will not be possible to solve the problem by simply of complex systems, and also have enormous openlab and increasing the total computing resources available. potential for the benefit of wider society. CERN has 20 years’ It is therefore vital to explore new technologies openlab, with its unique collaboration with several experience leading and methodologies in conjunction with the world’s of the world’s leading IT companies, is ideally ICT projects across research and leading information and communication technology positioned to help make this a reality. www.lesker.com | Enabling Technology for a Better World industry. (ICT) companies. • openlab.cern.

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ULTRA HIGH VACUUM. News WE ARE THE INNOVATORS. A ccelerAtors The ultra high vacuum capabilities of our extensive range of products and nearly 100 years expertise in the field means you can trust us to provide a complete vacuum solution for your application. Xenon beams light path to gamma factory

Having revolutionised the dry vacuum pump in 1984, Edwards has led the technological On 14 September, CERN injected a beam advancement of dry vacuum pump innovation for more than 30 years. of partially ionised xenon atoms into the Super Proton Synchrotron (SPS) and kept it • With excellent compression for light gasses and class leading ultimate vacuum circulating for a short period. The successful M Brice/CERN performance, the Edwards nXDS scroll pump is the ideal dry backing pump to obtain ultra demonstration, carried out by the SPS high vacuum pressures in combination with our nEXT/STP turbo molecular pumps. operations and radio-frequency teams, is the first of a series of experimental steps to • The hermetically sealed bearing design completely eliminates hydrocarbon contamination explore the feasibility of a gamma-ray source and our advances in tip seal technology means a maintenance free period of more than with an intensity several orders of magnitude two years. higher that those currently in operation. Earlier this year, CERN’s accelerator • New to the market Edwards is also able to offer the nXLi air cooled multi-stage roots complex demonstrated its flexibility by pumps with capacities of 110 or 200m3/hr making them ideal dry backing pumps for our producing a beam of fully ionised xenon atoms for the fixed-target experiment larger STP turbomolecular pumps. NA61, which studies the physics of strong interactions. Profiting from this achievement, the gamma-factory study group – which is part of CERN’s Physics Beyond Colliders study – requested dedicated beam tests with partially ionised xenon atoms in the SPS. The The SPS, pictured during a recent technical stop, was loaded with beams of partially ionised beam was composed of xenon nuclei carrying xenon atoms in September. 15 out of the 54 electrons present in the 2 neutral atom, the missing 39 electrons having is boosted by a factor of up to 4γL, where γL complementary to high-energy colliders and been stripped off before reaching the SPS. is the Lorentz factor of the ion beam. With other initiatives in the world” (CERN Courier The xenon beams injected into the SPS the LHC as a storage ring, photons in the November 2016 p28). are the most fragile of any beam so far energy range 1–400 MeV would therefore be accelerated to, and stored at, ultra-relativistic possible. Such a source of gamma rays would energies at CERN. A loss of even a single open many scientific opportunities, such as Sommaire en français electron changes the magnetic rigidity of precision atomic electroweak physics with Des faisceaux de xénon illuminent la voie 7 the stored particles and leads to beam loss. high-Z hydrogen-like atoms, dark-matter vers l'usine à gamma The losses for the xenon-39 beam due to searches using photon beams, and neutron CLEAR explorera des techniques 8 interactions of the beam with the residual gas dipole moment and neutron–antineutron d'accélération in the SPS vacuum pipe were expected to be oscillations. It would also act as a test bed for severe, and the tests confirmed that the beam a future neutrino factory or a TeV-scale muon Premier faisceau pour la source de neutrons 9 lifetime is indeed short (of the order of one collider, says the team. chinoise second). However, the lifetime is expected Meanwhile, independent activities during Royaume-Uni : plus de crédits pour les 9 to be significantly higher for lead beams machine-development periods this year will neutrinos with only one or two attached electrons, see xenon atoms injected and brought into which are the principal candidates to drive collision in the LHC. “The beauty of the RHIC : spin record pour un fluide 10 the high-energy gamma factory. Tests with operation mode of the CERN accelerator LHCb teste l'universalité de la saveur 11 lead atoms will be carried out next year in complex is not only that the xenon-39 leptonique parasitic mode during the LHC’s heavy-ion beam tests in the SPS could be done with programme, when the CERN accelerator no influence on the LHC pp operation, but CMS : observation de quarks top dans les 11 teams aim not only to inject partially ionised that they could be done concurrently to collisions proton-noyau lead atoms into the SPS but also into the LHC. injecting and accelerating other types of ATLAS réalise des mesures précises de la 12 beam in the SPS – e.g. two cycles for the Light source fixed-target programme and one parasitic masse du quark top An eventual gamma factory would use beams cycle for xenon-39,” says Witold Krasny of ALICE étudie de possibles tétraquarks 13 of highly ionised atoms to drive a novel type the gamma-factory study group. légers of light source. The idea is to insert the ion CERN’s Physics Beyond Colliders beams into a storage ring and illuminate initiative was launched in 2016 to explore L'encre des tatouages nocive pour 15 them with a laser that excites the electrons to the opportunities offered by the CERN l'organisme ? a higher energy state, leading to spontaneous accelerator complex and infrastructure “to get Premier trou noir de masse intermédiaire 17 emission of secondary photons. In this new insights into some of today’s outstanding scheme, the initial laser-photon frequency questions in particle physics through projects

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F a c i l i t i e s tungsten target for the first time. Neutron CLEAR prospects for accelerator research IHEP China neutron detectors located at two of the facility’s 20 beamlines measured the neutron spectrum, A new user facility for accelerator R&D, Linear Collider (CLIC), which ended range of ideas in the accelerator field. showing that the neutron beam had been the CERN Linear Electron Accelerator for a successful programme in December CLEAR’s primary goal is to enhance and source sees successfully produced. The spectrum was Research (CLEAR), started operation in 2016. Following approval of the CLEAR complement the existing accelerator R&D consistent with the prediction from Monte August and is ready to provide beam for proposal, the necessary hardware programme at CERN, as well as offering a Carlo simulations, with a higher neutron experiments. CLEAR evolved from the modifications started in January and the training infrastructure for future accelerator first beam yield than expected. former CTF3 test facility for the Compact facility is now able to host and test a broad physicists and engineers. The focus is on Construction of the first three neutron general accelerator R&D and component In late August, the China Spallation Neutron spectrometers is also complete. A studies for existing and possible future Source (CSNS) produced its first neutron general-purpose powder diffractometer accelerator applications. This includes beam, representing an important milestone An aerial view of the CSNS facility in August will be used to study crystal and magnetic studies of high-gradient acceleration for the $280 million project. The world’s this year. structures of materials, while a small-angle PT2026 NMR Precision Teslameter methods, such as CLIC X-band and plasma fourth pulsed spallation neutron source, neutron-scattering instrument will technologies, as well as prototyping and following ISIS in the UK, SNS in the US and a beam of neutrons that have been knocked probe structures such as polymers at the validation of accelerator components for the J-PARC in Japan, CSNS is located in the out of the target nuclei. CSNS is driven by a level of 1–100 nm. A third instrument, a Reach new heights high-luminosity LHC upgrade. city of Dongguan in Guangdong province 80 MeV H – linac and a 1.6 GeV rapid cycling multipurpose reflectometer, will analyse The scientific programme for 2017 and is expected to become an important synchrotron, providing a 100 kW proton neutrons reflected from a sample to study the includes: a combined test of critical CLIC base for research and innovation in China beam. The protons strike a solid tungsten surface and interface structure of materials. in magnetic eld technologies, continuing previous tests and the surrounding region. CSNS entered target and the emerging neutrons are slowed These and other instruments will soon be performed at CTF3; measurements of construction in 2011 and is being built and using three moderators, before being available to users from around the world for measurement radiation effects on electronic components operated by the Institute of High Energy delivered to the instrumentation facilities. A research in materials science and technology, to be installed on space missions in a Jovian Physics in collaboration with the Institute of second phase of the project, upgrading the life sciences, physics, the chemical industry, The Metrolab PT2026 sets a new environment and for dosimetry tests aimed at Physics, both part of the Chinese Academy linac to 250 MeV and the proton beam power environment, energy and other fields. medical applications; beam instrumentation of Sciences. to 500 kW, is planned for the near future. Commissioning of the spectrometers is standard for precision magnetometers. R&D; and the use of plasma for beam A spallation neutron source uses intense At 10.56 a.m. on 28 August, a proton beam under way, on track for the facility to open to Leveraging 30 years of expertise building focusing. Further experiments, such as those pulses of protons to strike a target, producing pulse from the accelerator collided with the users in the spring of 2018. exploring THz radiation for accelerator the world’s gold standard magnetometers, applications and direct impedance F u n d i n g it takes magnetic  eld measurement to measurements of equipment to be installed J Ordan/CERN and M Brice in CERN accelerators, are also planned. UK neutrino

new heights: measuring higher elds with M Brice/CERN better resolution. The experimental programme for 2018 and beyond is still open to new and investment steps up challenging proposals. An international The PT2026 offers unprecedented  exibility scientific committee is currently being € in the choice of parameters, interfacing formed to prioritise proposals, and a user The UK is to invest £65 million ( 74 million) request form is available at the CLEAR in the Long-Baseline Neutrino Facility and probe placement, as well as greatly website: cern.ch/clear. (LBNF) and Deep Underground Neutrino Experiment (DUNE) in the US, announced

improved tolerance of inhomogeneous M Volpi UK science minister Jo Johnson on elds. And with Ethernet & USB interfaces 20 September. Currently under construction and LabVIEW software, it  ts perfectly into On 12 September, 56 servers left CERN at Fermilab and Sanford Underground modern laboratory environments. bound for the SESAME light-source Research Laboratory, LBNF/DUNE will facility in Jordan. “These servers are a investigate crucial questions about neutrinos

www.agence-arca.com - Photo: Scott Maxwell, Master le - Photo: Scott Maxwell, Master www.agence-arca.com very valuable addition to the SESAME such as their mass ordering and CP-violating data centre,” said Salman Matalgah, head properties. of IT at SESAME. “They will help ensure The latest investment makes the UK, Prototype liquid-argon detectors for the that we’re able to provide first-class already a major scientific contributor international DUNE project are currently computing support to our users.” Speaking with 14 universities and two Science and being built at CERN. for CERN, Charlotte Warakaulle, director Technology Facilities Council laboratories for international relations, said: “After providing expertise and components, the system) and in the neutrino beamline many other successful donations, it’s great largest country in the LBNF/DUNE project (super-conducting RF for the PIP-II LINAC that we can extend the list of beneficiaries outside of the US. and the LBNF neutrino target).” to include SESAME: a truly inspiring “We have been working towards this LBNF/DUNE is the first major project to project showcasing and building on for a long time and it is important both be addressed by a broader UK–US science scientific capacity in the Middle East and for the UK and for DUNE overall,” says and technology agreement, the first between Pantone 286 Pantone 032 neighbouring regions.” Pictured are co-spokesperson of the DUNE collaboration the two countries, signed in January to CERN’s head of IT Frédéric Hemmer Mark Thomson of the University of strengthen UK–US co-operation. CLEAR’s plasma-lens experiment will test (left), Charlotte Warakaulle and president Cambridge. “Specifically, the investment CERN is an important partner in LBNF/ ways to drive strong currents through a of SESAME Council Rolf Heuer, with the will allow the UK to play a major role in DUNE and is developing prototype Magnetic precision has a name www.metrolab.com plasma for particle-beam transverse servers packed and ready to go. the construction of the DUNE far detector liquid-argon detectors for the project as part focusing. (read-out TPC wire planes and DAQ of its dedicated neutrino platform.

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H e a v y i o n s L H C experiments Charged particles Fastest spinning from a gold–gold nuclei collision in the LHCb digs deeper into lepton-flavour universality fluid clocked STAR detector. Measurements of the The LHCb collaboration ) 4

data data data /c LHCb alignment between the has released yet another 2 14000 LHCb by RHIC global angular result in its campaign to test 4000 momentum of lepton-flavour universality. 10000 non-central collisions Following anomalies already detected in 2000 6000 Experiments at the Relativistic Heavy Ion and the spin of emitted the rate that B mesons decay into muons 2000 Collider (RHIC) at Brookhaven National particles reveal that compared to electrons or tau leptons, the latest candidates/(0.376 ps) 5 + candidates/(0.6 GeV 5 Laboratory have found that droplets of the QGP is the most result concerns the charmed B meson, Bc. 0 pulls 0 quark–gluon plasma (QGP) can spin faster vortical system so far Using data recorded at collision –5 pulls –5 –5 0 5 10 0.5 1.0 1.5 2.0 than any other fluid. The immensely hot and observed. energies of 7 and 8 TeV during LHC 2 2 4 fast-expanding QGP is already known to Run 1, LHCb reports evidence for the mmiss (GeV /c ) τ (ps) + + behave as a near “perfect” liquid, exhibiting semi-tauonic decay Bc → J/ψ τ νt and has a viscosity lower than any other. Now, performed a measurement of the ratio 1D projections of the 3D fit to the data in two of the fit variables: the invariant-mass squared + + + + researchers on RHIC’s STAR experiment R(J/ψ) = Br(Bc → J/ψ τ νt)/Br(Bc → J/ψ μ νm). of the neutrino system (left) and the decay time of the selected Bc candidates (right). report that the vorticity (or curl) of the fluid The ratio is found to be 0.71±0.17±0.18, produced in RHIC’s relativistic heavy-ion which is within 2σ of the expected Standard source of background when one or more The combined effect is now almost at the collisions is about 9 × 1021 s–1. That exceeds plasma and, with more data, offer a way might even form in collisions involving very Model (SM) range of 0.25–0.28. The SM particles in their final states are misidentified level of 4σ with respect to the SM prediction. the rotation of a super-cell tornado by a to measure the strength of the plasmaʼs light nuclei such as deuterium – in line with prediction of R(J/ψ) deviates from unity only in the detector. Fortunately, the presence of In addition, previous LHCb analyses of 20 (*) + – (*) + factor 10 and is 14 orders of magnitude magnetic field. recent observations by the LHC experiments due to the large mass difference between the two heavy quarks in the Bc means it decays B → K μ μ and B → K e e decays also higher than any fluid ever observed, The past decade has seen major advances of proton-collision systems. tau and the muon. nearly three times faster than its lighter deviate from the SM by about 2.5σ. beating the previous spin record held by in our understanding of the quark–gluon Both the semi-muonic decay, cousins, providing a powerful handle for There is much more to come from LHCb ● Further reading + + nano-droplets of superfluid helium. The plasma, with RHIC experiments also Bc → J/ψ μ νm, and the semi-tauonic statistically separating their respective on tests of lepton-flavour universality, which STAR Collaboration 2017 Nature 548 62. + + + – results will aid descriptions of quark–gluon reporting recently that the extreme state decay, B c → J/ψ τ νt, with J/ψ → μ μ and contributions. remains one of the most enduring hints + + τ → μ νμ νt(bar), lead to a three-muon final The latest LHCb result adds to the of deviation from the SM. This includes state with the two channels distinguished intriguing picture emerging from the updates of the results with Run-2 data and by their decay kinematics. Despite the measurements of semi-tauonic decays of measurements from other b-hadron species. distinct signature, however, the analysis b-flavoured hadrons. Previous studies of must overcome several major challenges. For the ratios of branching fractions between ● Further reading (*) + (*) + example, since Bc mesons account for less B → D τ νt and B → D μ νt at LHCb, LHCb Collaboration 2017 LHCb-PAPER-2017-035. than 0.1% of the b hadrons produced at the BaBar and Belle have shown hints of LHCb Collaboration 2017 arXiv:1708.08856. DESIGNED FOR CITY LIFE LHC energies, light b hadrons are a major departure from lepton-flavour universality. LHCb Collaboration 2015 Phys. Rev. Lett. 115 111803. –1 The Volvo V40 is the compact hatchback that’s perfectly suited for life in the city. With agile CMS observes top pPb CMS pPb (174 nb , √s NN = 8.16 TeV) 3 l + jets (divided by A = 208) handling, interior versatility and smart technology to make your life easier, the V40 is the 10 CMS e±/μ± + ≥4j (≥2b) perfect companion as you start your journey. quarks in proton– pp eμ / μμ / l + jets data pPb (174 nb–1, 8.16 TeV) 30 Volvo Cars has been serving the Diplomat community since 1956 and offers one of the most l + jets tt correct eμ 300 comprehensive diplomat sales programs in the market. Order your new Volvo V40 from your nucleus collisions 200 tt wrong

local Volvo Diplomat dealer and benefi t from a premium level of service. cross-section (pb) TOP++ NLOMCFM × K e + jets 2 100 NNLO background 10 CT10+EPS09 μ + jets + 20 CT14+EPPS16 l jets 2 NNLO+NNLL(Top++) χ /dof = 32.1/50 The top quark, the heaviest Czakon, Fiedler, Mitov 2013 PRL 110 252004

Volvo V40 NNPDF3.0, mtop = 172.5 GeV, αs(MZ) = 0.118±0.001 events elementary particle in the inclusive tt Volvo V40 is offered with Kinetic trim as standard. When you add the Inscription trim, Standard Model, has been 6810 12 10 Diplomat package and Metallic colour all combined, instead of normal combination price of centre-of-mass energy (TeV) €5,005, you pay only €1,005 and save €4,000. the subject of numerous detailed studies in proton– THIS OFFER INCLUDES Active digital display with chrome, Navigation, Keyless start, Park assist camera, Park assist rear, Park antiproton and proton–proton collisions at (Above) Top-quark pair-production 0 assist front, Audio system ”High Performance Multimedia” with Sensus connect, 17” alloy “Sarpas” the Tevatron and LHC since its discovery at cross-section in pp and pPb collisions as a 100 200 300 400 wheels, LED headlights “Thor’s hammer”, Leather gear shift knob, Leather handbrake lever, Leather m (GeV) steering wheel with décor inlays, Rain and tunnel sensor, Interior light package, Power foldable door Fermilab in 1995. Until recently, however, function of the centre-of-mass energy per top mirrors with puddle lights, Leather upholstery and more. studies of top-quark production in nuclear nucleon pair. (Right) Invariant mass collisions remained out of reach due to the distribution of the hadronic top-quark (pQCD) methods, thus making this quark Volvo V40 D2 (120 HP) Man with Kinetic trim €17,970 with the complete offer above €18,320 small integrated luminosities of the first candidates in selected events with two a “standard candle” and a tool for further Offers available on other engines and other trim level. Please contact your local Diplomat Dealer for more information. heavy-ion runs at the LHC and the low b-tagged jets. investigations. In proton–nucleus collisions, nucleon–nucleon (NN) centre-of-mass in particular, the top quark is a novel probe of [email protected] Offer valid until October 31, 2017 for MC10 European specifi cation, left-hand drive, model year 2018. energies (√sNN) available at other colliders first-ever study of top-quark production in the nuclear gluon density at high virtualities The car on the image may contain extra equipment not included in the offer. such as RHIC in the US. nuclear collisions. in the unexplored high Bjorken-x region. In Proton–lead runs at √s = 8.16 TeV Top-quark cross-sections at the LHC addition, a good understanding of top-quark > AUTOBRITT AUTOMOBILES SA RUE VIGUET 1 | ACACIAS 022 308 57 00 NN

> AUTOBRITT GRAND-PRÉ SA RUE GRAND-PRÉ 2 | SERVETTE 022 919 05 00 performed in 2016 at the LHC have allowed can be computed with great accuracy via production in proton–nucleus collisions s the CMS collaboration to perform the perturbative quantum chromodynamics is crucial for studies of the space–time

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structure of the quark–gluon plasma formed non-top background is constrained by two background-only hypothesis corresponds 8 in nucleus–nucleus collisions. complementary event samples, with zero or to a significance of more than 5σ, even ALICE studies possible light tetraquark ALICE Pb–Pb √s = 2.76 TeV NN Once produced, each top quark decays one b-tagged jets, also included in the fit. under the most conservative assumptions. 0–10% promptly into a W boson plus a bottom In this way, the background behaviour in The measured top-pair cross-section is quark, with the W boson further decaying this (so far unexplored) phase-space region consistent with the expectations from scaled The a0(980) resonance is of 2.76 TeV, ALICE fitted the experimental 6 into either a charged lepton and a neutrino and the b-tagging efficiency are evaluated proton–proton collision data as well as formally classified by the two-kaon yield to extract the radius and or a pair of light quarks. To identify in situ with only minimal assumptions, pQCD predictions at next-to-next-to-leading Particle Data Group as a light emission strength of the kaon source R (fm) pair-produced top quarks, CMS therefore independent of prior inputs. As a validation, order with next-to-next-to-leading-log diquark (quark + antiquark) assuming only a final-state interaction K±K± selected events containing one isolated the outcome of the fit is used to model accuracy (figure, right). This result paves meson similar to the pion. through the a (see figure). 4 0 K0K0 electron or muon, two “b-tagged” jets, and the signal and background invariant the way towards future studies of top-quark However, it has long been considered as Both the radii and the emission strength s s 0 ± K0K± two jets that fail b tagging. The amount of mass distributions of the top-quark production in the hot and dense matter a candidate tetraquark state made up of from the KS – K analysis agree with the s Achasov2 parameters signal in the selected sample is inferred candidate in the hadronic decay channel created in nucleus–nucleus collisions. two quarks and two antiquarks. Existing identical kaon results, suggesting that the 2 0 ± by a fit to the invariant mass of the two (t → Wb → qqʹb), which are in agreement experimental evidence based on the final-state interaction between the KS and K 0.2 0.6 1.0 untagged jets, interpreted as W boson with the data (see figure). ● Further reading radiative decay of the φ meson has not been goes solely through the a resonance without 0 kT (GeV/c) decay products (W → qqʹ). The amount of The excess of events with respect to the CMS Collaboration 2017 arXiv:1709.07411. convincing, so the ALICE collaboration any competing non-resonant channels. A took a different approach to study the a0 by tetraquark a0 is expected to couple more Radius parameters versus average 0 ± measuring K S – K correlations in lead–lead strongly to the two kaons, since it has the transverse kaon-pair momentum 0 ± ATLAS experiment makes precision collisions at the LHC. Since the kaons are not same quark content, while the formation determined from KS – K correlations and identical there is no Hanbury–Brown–Twiss of a diquark state requires the annihilation identical-kaon correlations in central measurement of top-quark mass interferometry enhancement, and since the of the strange quarks, which is suppressed ALICE lead–lead collisions. 0 KS is uncharged there is no Coulomb effect. due to geometric effects and a selection Nevertheless, because the rest masses of the rule. Although there are no quantitative identical-kaon values. The ALICE result of The top quark is two kaons reach the threshold to produce predictions for the magnitude of this the final-state interaction going solely via the ATLAS preliminary data, l + jets combinations ATLAS preliminary m ± syst.± best-fit background top stat. copiously produced 1200 √s = 8 TeV, 20.2 fb–1 the a0 it is expected that there is a strong suppression that would result for a diquark a0 thus favours the interpretation of the a0 as a at the LHC, allowing best fit CDF (Mar 2014) ±173.16 0.57 0.74± final-state interaction between the two kaons form of a , the qualitative expectation is that tetraquark state. uncertainty 0 for very precise D0 (Jul 2016) ±174.95 0.40 0.64± through the a0 resonant channel. this would open up non-resonant channels 800 ● measurements of its properties. The mass Using the data from central lead–lead that would compete with the a0 final-state Further reading CMS (Apr 2016) ±172.44 0.13 0.47± of the top quark, mtop, plays a special role collisions with a nucleon–nucleon energy interaction, making it smaller than the ALICE Collaboration 2017 Phys. Lett. B 774 64.

in the Standard Model (SM) of particle ATLAS (Sep 2017) ±172.51 0.27 0.42± events / GeV 400 physics. It is a key part of the mechanism of ATLAS combination electroweak symmetry breaking and one of stat. uncertainty stat. uncertainty total uncertainty total uncertainty the parameters governing the stability of the 0 universe in the SM. 140 160 180 200 165 170 175 180 reco Following years of meticulous work, mtop (GeV) mtop (GeV) ATLAS presented a new measurement of mtop at the 10th International Workshop on (Left) The reconstructed top-quark mass recorded at 8 TeV together with the best-fit template. Top Quark Physics held in Braga, Portugal, (Right) the new ATLAS combined result compared to those from other experiments. in late September. The measurement was performed using around 100,000 proton– where the final-state objects are incorrectly thereby reducing the correlation among the proton collision events at an energy of assigned to the two top quarks. While measurements. The combined result thus has 8 TeV, each containing a top-quark pair only retaining 40% of the events, the total a 41% smaller uncertainty than the single reconstructed in the single-lepton final state. uncertainty is improved by 19%, leading to a most precise measurement. The current In this channel, each top quark immediately top-quark mass of 172.08±0.91 G eV. combined value is 172.51±0.50 GeV with a decays to a W boson and a bottom quark, and The power of this measurement, which relative precision of 0.29%, which is mainly one W boson decays to an electron or muon is the second most precise individual limited by the calibration of the jet-energy and a neutrino, while the second W boson top-quark mass measurement made by scales and is similar to that of the leading decays to two light quarks. ATLAS to date, is revealed when combined single-experiment combined measurements. A simultaneous measurement of mtop with previous ATLAS measurements The current precision on mtop represents a together with a global jet-energy scale factor in the single-lepton channel at 7 TeV significant achievement that demonstrates and a relative bottom-to-light jet-energy and the dilepton channel at 8 TeV. This the precise understanding of all the relevant scale factor was performed. The inclusion combination relies on a careful evaluation aspects of the ATLAS detector. The of these scale factors strongly reduces of the correlation between measurements measurement will allow further and deeper systematic uncertainties. The precision for all sources of systematic uncertainty. tests of the consistency of the SM. of the measurement is further improved In both channels at 8 TeV, the analysis by differentiating between correctly optimisation trades reduced systematic ● Further reading reconstructed top-quark events and events against increased statistical uncertainty, ATLAS Collaboration 2017 ATLAS-CONF-2017-071.

Les physiciens des particules du monde entier sont invités à apporter leurs CERN Courier welcomes contributions from the international contributions au CERN Courier, en français ou en anglais. Les articles retenus particle-physics community. These can be written in English or French, seront publiés dans la langue d’origine. Si vous souhaitez proposer un article, and will be published in the same language. If you have a suggestion for faites part de vos suggestions à la rédaction à l’adresse [email protected]. an article, please send proposals to the editor at [email protected].

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C o m p i l e d b y J o h n S w a i n , n ortheaStern U n i v e r S i t y Tattoo ink travels in body

The inks in tattoos are supposed to remain The hazards that potentially derive from confined to the skin, but a recent study tattoos had previously only been by Andreas Luch of the German Federal investigated by chemical analysis of the inks Institute for Risk Assessment in Berlin and and their degradation products in vitro. colleagues shows that elements within inks are transported in micro- and nanoparticle such as heavy metals and titanium dioxide. forms from the skin to regional lymph Fourier-transform infrared spectroscopy also nodes. The team used synchrotron X-ray revealed ultrastructural changes in tissue next Award Winning Technology fluorescence at the European Synchrotron to tattoo particles and elevated lipid contents, in Grenoble, France, to track the presence of which may contribute to inflammation and Ampegon’s power supplies and pulse modulators provide unlimited benefi ts for any Accelerator System. various elements ex vivo in tattooed tissues. other problems associated with tattooing. Our Type µ short pulse modulator received the Swiss Technology Award 2016. Out of all nominated products, the Type µ The results revealed the first evidence for the was chosen for the highest levels of technological innovation, combined with both economical and social benefi ts. transport of various organic and inorganic ● Further reading pigments and toxic-element impurities, I Schreiver et al. 2017 Sci. Rep. 7 11395. Three hundred kinds of ice Helicity dynamics in water Climate and leaf size Transmission Antenna Scientifi c Green ampegon.com Science MedTech Industry Broadcast Ice is commonly thought to have a hexagonal Vortices are an interesting feature of fluid Systems Systems Applications Technologies crystal structure, as reflected in the symmetry The sizes of leaves vary by more than five motion. William Irvine of the University of of snowflakes. Along with cubic ice, which is orders of magnitude among plant species Chicago and colleagues have now shown that found in the upper atmosphere, these are the worldwide, yet the reason why has remained the helicity of vortices, which is a measure only crystalline forms of ice found in nature mysterious. Ian Wright of Macquarie of the degree to which vortex lines wind so far. Now, Takahiro Matsui and colleagues University in Australia and colleagues have around each other, can remain constant even at Okayama University in Japan suggest that now characterised the patterns of leaf sizes in viscous fluids. Helicity is conserved in the this is merely the tip of the iceberg. Using for 7670 plant species together with climatic absence of viscosity, but can be dissipated in HIGH VOLTAGE. EXACTLY. classical molecular dynamics simulations, the data from 682 sites worldwide, and report real (viscous) fluids. Observing the twisting, team found over 300 new kinds of porous ice consistent patterns that explain why earlier linking and writhing of hydrofoils in water, structures derived from zeolite frameworks predictions had limited success. The results the team shows that twisting dissipates vortex and space fullerenes. Despite being a vast also provide a quantitative explanation for tubes while writhing and linking conserve EHS STACK PRECISION FOR GEM-DETECTORS increase over the 17 ice polymorphs found leaf-size variation with latitude: for much of the them. The result could allow helicity to experimentally so far, they only exist at world, a key factor limiting leaf size turns out to be manipulated in real fluid flows, with CASCADED OUTPUTS FOR MULTILAYERED MICROPATTERN GAS DETECTORS very low – even negative – pressures and be night temperature and the associated risk of implications for atmospheric flows ranging temperatures near absolute zero. frost damage. from turbulence to the formation of tornados. SAMPLE CONFIGURATIONSAMPLE CONFIGURATION HV-CHANNEL HV-CHANNEL0 1 2 3 4 5 0 6 1 7 2 8 3 9 4 10 5 11 6 12 7 13 8 14 9 15 10 11 12 13 14 15 ● Further reading ● Further reading ● Further reading 8 / 16 channel, voltages from 0-1 kV customized per channelEMS 168 n001 (2 x 8 High EMSPrecision 168 n001 channels (2 x 8cascade) High Precision channels cascade) GROUP GROUPG1 G1 G1 G1 G1 G1 G1 G1 G1 G1 G1 G2 G1 G2 G1 G2 G1 G2 G1 G2 G1 G2 G2 G2 G2 G2 G2 G2 G2 G2 G2 G2 T Matsui et al. 2017 J. Chem. Phys. 147 091101. I Wright et al. 2017 Science 357 917. M Scheeler et al. 2017 Science 357 487. cascadable channels in groups of 2, 4, 8 or 16 channels POLARITY POLARITYn n n n n n n n n n n n n n n n n n n n n n n n n n n n n n n n OUTPUT VOLTAGE V in VOUTPUT 800 400 VOLTAGE 800 400 V 800 in 400 V 800 800 400 400 800 800 400 400 800 800 400 400 800 800 400 400 800 800 400 400 800 400 800 400 800 400 High Precision voltage and current measurement per channel nom nom OUTPUT CURRENT I in mAOUTPUT 1 1 CURRENT 1 1 I 1 in mA 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 nom nom Rat nightmares Farewell to Cassini very low ripple and noise, very low temperature coeffi cientRESOLUTION of Vset in mV RESOLUTION 40 20 40 of 20Vset in 40 mV 20 40 40 20 20 40 40 20 20 40 40 20 20 40 40 20 20 40 40 20 20 40 20 40 20 40 20 RESOLUTION of I in nA RESOLUTION 20 20 20 of 20I in 20 nA 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 max. 4 kV fl oating voltage set set Nightmares are familiar to humans, but it On 15 September, having expended the last RESOLUTION of Vmeas in mVRESOLUTION 4 2 4 of V 2meas 4in mV 2 4 4 2 2 4 4 2 2 4 4 2 2 4 4 2 2 4 4 2 2 4 2 4 2 4 2 RESOLUTION of I in nA RESOLUTION 5 5 5 of I 5 in 5 nA 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 synchronized ramps meas meas now seems rats can have them too. Gabrielle of its rocket propellant, NASA’s Cassini * * RESOLUTION of Imeas in pARESOLUTION 100 100 100 of 100 Imeas 100 in pA 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 programmable parameters like voltage drop compensation* 2nd measurement range * 2nd measurement range Girardeau and colleagues at New York probe was deliberately crashed into University put rats in a maze and blasted them Saturn following an epic two-decade-long in the face with an unpleasant, yet harmless, journey of exploration. The mission has burst of compressed air. As the rats slept later, revolutionised our understanding of the patterns of activity arose in their hippocampi complex Saturn system, in particular corresponding to their mental map of the its moons and rings, and broadened our maze, but activity in the amygdala, a region knowledge about life in the solar system.

NEW CATALOG involved in emotion, also showed up whenever The first spacecraft to orbit Saturn, Cassini OUT NOW the blast of air was activated. has led to hundreds of scientific papers and 2017 / 2018 Plants outside of tropical climes have shaped the future of planetary exploration. ● Further reading smaller leaves that are more robust G Girardeau et al. 2017 Nat. Neurosci. doi:10.1038/ against cold. ● Further reading nn.4637. saturn.jpl.nasa.gov. information and downloads on: www.iseg-hv.com 15 170927_CERNcourier_November_EHS_stack-GEMS_Halbseite .indd 1 27.09.17 17:10

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C o m p i l e d b y m e r l i n K o l e , d e pa r t m e n t o f pa r t i C l e p h y s i C s , U n i v e r s i t y o f G e n e va EVC-15 First intermediate black-hole candidate

Since the prediction of black holes a century in the centre with a large velocity profile, ago, numerous black-hole candidates have 0 10 20 30 surrounded by 20 smaller clouds, the 15th European Vacuum been found. These consist of both low-mass Nat. Astron. –0.21 (Jy beam–1 km s–1) velocity profiles of which are aligned. black holes, which have several times the Since the probability of these clouds being a Conference 17-22 June 2018 mass of the Sun, and supermassive black b aligned by chance is less than one part in Geneva Switzerland holes (SMBHs), which are billions of times c 108, it suggests there is some other object heavier. While many candidates exist for –0.22 close to the cloud interacting with it. Within stellar-mass black holes and SMBHs, the the gas cloud the data also revealed a point latter being thought to occupy the centres of source emitting weak electromagnetic galaxies, candidates for black holes in the galactic latitude (°) radiation at submillimetre wavelengths and HPBW intermediate mass range were lacking. –0.23 none at higher wavelengths, ruling out a A group of researchers from Keio massive star cluster. University in Japan has now shown Based on these striking observations, strong evidence for the existence of an –0.39 –0.40 –0.41 the group simulated the gravitational intermediate-mass black hole (IMBH) galactic longitude (°) interactions of the cluster and found that the within the Milky Way, which could shed measured velocity profiles are consistent light on the formation of black holes and of Integrated emission from the gas cloud, with a gravitational kick by a dense object our galaxy. where the cross marks the black hole and the of 105 solar masses. Combined with the www.evc15.org While there is a consensus that arrows indicate the measured velocity lack of high-energy emission and the stellar-mass black holes form when massive directions. The white filled circle and black spectrum of the object measured in radio C CERN stars die, the source of SMBHs – one of filled ellipse show the beam sizes of ASTE wavelengths, the object matches all the which is thought to be at the centre of the and ALMA, respectively. characteristics of an IMBH – the first one Milky Way – is not well known. It is believed ever observed. Two further IMBHs are that large galaxies such as the Milky Way profile, hinting that an IMBH exists near the now under study. The finding opens a new grew to their current size by cannibalising centre of our galaxy. This then prompted a research avenue in understanding both smaller dwarf galaxies containing IMBHs more precise observation of the area using massive and supermassive black holes, and at their centres. Finding a candidate IMBH the Atacama Submillimeter Telescope strengthens the hypothesis that our galaxy would provide evidence for this theory. Experiment (ASTE) and Atacama Large grew by cannibalising smaller ones. First, using the Nobeyama radio Millimeter/submillimeter Array (ALMA) telescope, the team detected a gas cloud in Chile. The cloud, named CO-0.40-0.22, ● Further reading T Oka et al. 2017 Nat. Astron. 1 709. Surpass design challenges in the Milky Way with a peculiar velocity was found to consist of one dense cloud with ease using COMSOL Multiphysics®. Picture of the month Work with its powerful mathematical modeling This image of the Sun shows a large solar flare (on the right side of tools and solver technology the picture) coming from a giant active region called AR2673 just to deliver accurate and as the region is about to disappear behind the solar horizon. Since comprehensive simulation 6 September, AR2673 has been responsible for several flares results. including the largest seen in more than a decade. The large flare shown here, captured in ultraviolet by the Atmospheric Imaging VERIFY AND Develop custom Assembly on the Solar Dynamics Observatory mission, was applications using the followed by a large coronal mass ejection (CME) on 10 September. OPTIMIZE Application Builder and While solar flares are responsible for emission in the ultraviolet deploy them within and X-ray regions, gamma-rays with an energy of several GeV your organization and have been measured in the past by the Fermi-LAT satellite. CMEs. NASA, SDO, and the AIA, EVE and HMI science teams YOUR DESIGNS to customers worldwide ® which often follow solar flares, are responsible for the ejection of with COMSOL Multiphysics with a local installation of high-energy electrons and protons into the solar system resulting COMSOL Server™. in the Northern Lights. Although the CMEs coming from this region The evolution of computational tools for resulted in spectacular Northern Lights, much stronger CMEs numerical simulation of physics-based Benefi t from the power have occurred in the past. In 1859 a CME was strong enough to systems has reached a major milestone. of multiphysics today cause auroras to be visible at latitudes as low as Cuba, while the comsol.com/products results of a very strong solar event in the year 775 are thought to be responsible for a large carbon-14 surplus found in tree rings around the world. © Copyright 2017 COMSOL.

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First issued in 1957, the Review of Particle Physics has become the number-one reference in high-energy physics, detailing more than 38,000 measurements and counting.

Teasing out the intricate measurements that separate the smallest components of matter in the universe often involves monumen- tal machines and huge international scientific collaborations. So PhotoPPhoPhotPhhhohotoottooc cocourtesycourteuurturrtertrtetesysyyo ofo fEf EUROfusion.EEU URROfROfuROOfuOffufussiosionsiioniioonon..W WWeWebsite:ebsbsitbsitssiitite:e:w: w www.euro-fusion.orgwwwww.ew.wweuro-urro-oo-fusfufusiusiusussiioon.oonon.nn.n.ono.o.o rrgg Photo courtesy of EUROfusion. Website: www.euro-fusion.org it’s important that particle physicists are on the same page – or, rather, pages – when it comes to particle-physics results. For the past 60 years, the definitive collection of particle-physics evalu- Imaging in radiation environments just got easier ations and reviews has been bound up in a weighty print volume called the Review of Particle Physics, which is published every other year. The latest (2016) edition of what is sometimes referred With superior capabilities for operating in radiation environments, the MegaRAD cameras provide to as the “bible of particle physics” contains 1808 pages in the com- plete version published online, and features 117 review articles on The latest (2016) PDG Review of Particle Physics leaning excellent image quality well beyond dose limitations of conventional cameras, and are well suited topics ranging from the Higgs boson to the Big Bang, statistics against all previous editions, with the oldest issues at the bottom. for radiation hardened imaging applications and particle detectors. Its Particle Listings include evaluations of 3062 new measurements from 721 papers, in addition to 35,436 than 200 authors around the globe currently contribute to the con- measurements from 9843 papers published in earlier editions. The tents of the Review, including 3.5 full-time-equivalent physicists staff behind it carefully evaluate data on around 8000 different in the PDG group at Berkeley Lab who also co-ordinate the effort. quantities to provide averages, fits and best limits. The story began towards the end of 1957 with a paper in the The Review is the all-time most highly cited publication in par- Annual Review of Nuclear Science authored by the late Arthur ticle physics, with recent editions eventually reaching more than “Art” Rosenfeld and Murray Gell-Mann. The tables of particle 6000 citations. It also has a companion 344 page booklet that is masses and lifetimes associated with that article, which Rosen- the descendant of “wallet cards” first issued in 1957, with a sum- feld prepared with Walter Barkas in an unpublished report, mary of particle data from the main Review. The PDG website “Data for Elementary-Particle Physics,” are credited with PDG’s MegaRAD3 produce color MegaRAD1 produce KiloRAD PTZ radiation (pdg.lbl.gov) features the complete content of the book as both PDF inception. “The damn thing just grew,” Rosenfeld said of the or monochrome video up to monochrome video up to resistant camera with files and in an interactive version, with downloadable figures and wallet-card summary of that 3 x 106 rads total dose 1 x 106 rads total dose Pan/Tilt/Zoom tables, as well as educational materials. The Review continues to first report, which now fills a grow as we learn more about the basic constituents of matter, and spiral-bound booklet. In the United States: International: its history reflects a field that is continuously evolving. The Review is the Rosenfeld said in 1975 that For customer service, call 1-800-888-8761 For customer service, call [01) 315-451-9410 all-time most highly the motivation for the origi- To fax an order, use 1-315-451-9421 To fax an order, use [01) 315-451-9410 Berkeley beginnings cited publication in nal 1957 report was to provide Email: sales.cidtec@thermofi sher.com Email: sales.cidtec@thermofi sher.com The Review of Particle Physics and its associated publications and particle data for early com- website are the products of the international Particle Data Group particle physics. puter programs that were used (PDG), which since its beginnings has been headquartered at the to process the data from new Find out more at thermofi sher.com/cidtec University of California Radiation Laboratory, now the Lawrence particle-physics experiments, s Berkeley National Laboratory (Berkeley Lab), in California. More including bubble-chamber

For Research Use Only. Not for use in diagnostic procedures. © 2017 Thermo Fisher Scientifi c Inc. All rights reserved. All trademarks are the property of Thermo Fisher Scientifi c and its subsidiaries unless otherwise specifi ed 19

CCNov17_PDG.indd 19 04/10/2017 16:03 CERNCOURIER www. V o l u m e 5 7 N u m b e r 9 N o v e mber 2 0 1 7 CERN Courier November 2017 CERN Courier November 2017 Particle Data Group Particle Data Group Image credits:Lawrence Berkeley NationalImage Laboratory credits:Lawrence Members of Berkeley Lab’s measurements added (per edition) PDG group in 2016. From left number of review to right: Paul Schaffner articles (graphics/web designer), Kirill pages in Review Lugovsky (software (journal publication) citations developer), Piotr Zyla (editor), (per edition) Dan Dwyer (staff scientist), PDG collaboration Juerg Beringer (group leader), Lawrence Berkeley National Laboratory (physicists) Michael Barnett (past group LBNL PDG group (physicists) leader), Wei-Ming Yao (staff scientist), Simone Pagan Griso 0 100 200 300 400 500 600 700 change (%) (staff scientist) and Cheng-Ju Lin (staff scientist). 900 B mesons accommodate the Higgs boson’s discovery, with staff scrambling experts from Berkeley Lab’s Computational Research Division, Masses and mean lifetimes of elementary particles, as shown in 800 light mesons to add the Higgs addendum to the Review within eight days of the Beringer led the development of a new web-based computing plat- Higgs bosons B Table I of the first wallet card issued in 1957. (Image credit: neutrinos discovery’s announcement on 4 July 2012. form that was supported by a special grant from the US Depart- 700 Barkas and Rosenfeld, UCRL-8030.) Z boson The scope and importance of PDG has grown substantially, ment of Energy (DOE). As a result, each collaborator can now top quark 600 especially during the past 30 years (figure 1 opposite). While the directly add data to the PDG database rather than channelling it all SUSY experiments. The following year the report was revised. The report size of the PDG group at Berkeley Lab has remained essentially through the PDG editor. This platform has made Review updates was next revised in 1961, and during these first few years of the 500 the same, a large number of physicists worldwide were recruited to far more manageable. “The new system allows collaborators to see Review Rosenfeld and his colleagues intermittently distributed 400 keep up with the flood of publications in particle physics and write changes immediately, without waiting for the editor to go through updates of the report to the particle-physics community, along with new entries the many PDG review articles that now cover almost every aspect thousands of e-mails with instructions on what to change,” says 300 the updated wallet cards. light mesons of particle physics. There are now 223 authors who contribute to Piotr Zyla, who succeeded Betty Armstrong as PDG editor in 2003. New discoveries in the field led to a growing need for particle- 200 the review articles or Listings and each will typically write a single As with any large-scale, data-intensive publishing endeavour, data resources, and Rosenfeld was clear that the 1963 edition SUSY H review article or handle one Listings section. Collaborators out- there have been a few notable glitches. The 1994 booklet had a ruler υ should be the last attempted without the help of a computer. A 100 side Berkeley Lab are volunteers who usually spend only a small with centimetre marks that were shrunk by the publisher so that t separate effort by Finnish physicist Matts Roos called “Tables of Z fraction of their time on the Review, while PDG group members each centimetre was actually 0.97 of a centimetre. The error was 0 Elementary Particles and Resonant States” also illustrated that it at Berkeley Lab typically spend half of their time working on the discovered too late to fix, but not too late to insert a disclaimer citing 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 was no longer possible for a single person to compile data critically, publication year PDG (image above). There is also a European-based PDG “meson fictitious and comical explanations for why the centimetres fell a bit reckoned Rosenfeld. So the two separate efforts joined forces, team” of about a dozen members, which holds meetings twice a short: “The PDG feels it has the right to redefine anything it wants”; with five Berkeley authors and Roos publishing “Data on Elemen- Fig. 1. Changes between the 1986 and 2016 editions of the Review year at CERN, while another PDG sub-group called the baryon “The booklets were returned from the printer at 0.25 times the speed tary Particles and Resonant States” in 1964. This article, which (top) and the number of measurements of selected particles added team is responsible for the data on baryon resonances. of light”; and “A theorist is in charge of the PDG.” appeared in the Reviews of Modern Physics journal, comprised to the Review as a function of the year of the edition (above). Michael Barnett, a Berkeley Lab physicist and previous head Barnett and his colleagues had considered publishing the 27 pages plus three wallet cards. of PDG having been in the role for 25 years, recalled his first Review on the internet since the early days of the World Wide Web The group branded itself as the Particle Data Group in 1968 and the PDG dropped its Listings from the print edition in 2016. experience working with the Review production when he joined – which, of course, was created at CERN in 1989 to more easily published its first data booklet that year. By 1974 the report, by then “We would have had to print two volumes if we continued to Berkeley Lab in 1984. “It was barely 300 pages long and still put share research data around the world. The entire contents of the called Review of Particle Properties, had grown to 200 pages and include the Listings. Given that there is likely no single person together by hand,” Barnett said. “We used 20 rolls of Scotch Tape Review were available on the web in 1995 and its interactive ver- had 13 authors, several of them based in Europe. An escalation of who wants to read through a major fraction of the Listings, this to stick pieces together for the camera-ready copy. The section sion, pdgLive, appeared with the 2006 edition. An increasingly discoveries in the field during the mid-1970s provided the corner- wasn’t justified,” recalls Juerg Beringer of Berkeley Lab, who on B mesons was a single page. These days the B-meson section sophisticated PDG web presence has been influenced by member- stones for the Standard Model of particle physics, which described became leader of the PDG in 2016. “Looking up data from the alone is over 120 pages.” In earlier days, the data for the publica- ship surveys asking readers whether in the digital age a printed the family of known and theorised particles and their properties. Listings online is anyway far more convenient.” The Listings are tions were stored on computer punch cards. The print data back book is essential, useful, or altogether unnecessary. The first sur- The heavy crush of particle data flowing into PDG during this still available on the PDG website and included in the online jour- then appeared as only uppercase letters, with no mathematical vey, in 2000, got about 2450 responses, half of which found the period led the staff to implement a new media format for distribut- nal publication. symbols, because the punch cards couldn’t accommodate them. print version useful and well over a third found it essential. By ing some data and additional quality-control measures. In 1973 a Under Barnett’s watch the design and layout became more reader- 2014 the number of responses microfiche with references and backup material was included in an Review articles friendly. Particle categories multiplied, with properties listed in had tripled. While there was a envelope at the back of the book. Many sections in the Listings are accompanied by review articles detail. Many new reviews were added to help explain the content clear trend in favour of online Since then, the population of particle physicists worldwide has that provide further information on the data presented. Other review of Listings sections. We used 20 rolls publications, many respondents exploded and the print version of the Review and related booklets articles summarise major topics in particle physics or cosmology. of Scotch Tape still emphasised the importance are currently distributed to thousands of physicists. INSPIRE, an Review articles can vary from about a page to tens of pages in Computing era to stick pieces of the printed book. As one information system that tracks published materials and experi- length, and roughly two-thirds of review articles require updates In the late 1980s a then-modern computing system was developed respondent stated in the 2000 ments in the field of high-energy physics, now counts more than in each edition. The first PDG review article on the Higgs boson, that served the PDG well for two decades. But a major upgrade together for the survey, “I could live without my 1100 active experiments in the field, compared to about 300 in which appeared in 1988, was two pages long. Today, five years after eventually became inevitable, and the COMPAS group from the camera-ready copy. right arm, but I don’t want to.” 1975, and the number of particle physicists has also increased from the Higgs was discovered, the review is about 50 pages long and Institute of High Energy Physics in Protvino, Russia, which had “We expected older physicists about 7000 in 1975 to an estimated 20,000 today. The print book is the most viewed review on the website, with more than 50,000 been a PDG collaborator for many years, began working on pro- to be the ones who valued the s was getting so big – growing at a rate of about 10% per year – that downloads each year. PDG even delayed publication in 2012 to totypes for a new computing system. Working with COMPAS and book and the younger ones,

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Lawrence Berkeley National Laboratory National Berkeley Lawrence Dual-Axis Charged Particle measurements of the same quantity. “Making all P data available 2.0 ␴ m1957–m2016 (1957) 100001 in a machine-readable format is a very high priority. Weve wanted to m1957 (MeV) m2016 (MeV) ␴ 40 √␴2 ␴2 (2016) Scintillating Fiber 1957 + 2016 do this for a long time as there are many uses and a lot of interest from – 1.8 e 0.510976 0.5109989461±0.0000000031 the community. ut we can barely keep up with the ongoing updates μ– 105.70±0.06 105.6583745±0.0000024 0.7 25000 of the Review, and so the implementation of such new features takes + π 139.63±0.06 139.57018±0.00035 1.0 171 much more time than we would like,” eringer says. UniBEaM is a new particle beam 1.6 π0 135.04±0.16 134.9766±0.0006 0.4 267 Rosenfeld, in the conclusion of his 1975 paper assessing the work K+ 494.0±0.2 493.677±0.016 1.6 13 of P, noted challenges even then in supporting the data needs K0 494.4±1.8 497.611±0.013 –1.8 138 of the scientifi c community: “As we write this review we wonder traditional wires. 1.4 p 938.213±0.01 938.272081±0.000006 –5.9 1667 if we have not been too modest in our requests for supportwe It is used to measure the beam Particle Data Group 2016 Chin. Phys. C n 939.506±0.01 939.565413±0.000006 –5.9 1667 feel that P is doing an effective job, but if we could spend, each mean lifetime (ps) + 1115.2±0.14 1115.683±0.006 –3.4 23 B 1.2 Λ year, one-fi fth of the typical experiment [in those days the typical particles with kinetic energies + 0.1 4 Σ 1189.4±0.25 1189.37±0.07 experiment cost about $3 million], it could provide broader and from keV to GeV and sensitive 0 +0.9 –2.4 Σ 1190.5–1.4 1192.642±0.024 38 more timely services.” to beam currents – 1.0 Σ 1196.5±0.5 1197.449±0.030 –1.9 17 The gradual transition from print to primarily online distribution from pA to mA. – –0.6 Ξ 1320.4±2.2 1321.71±0.07 31 is expected to continue, in line with the overall shift of publishers Table comparing several PDG masses in 1957 and in 2016. Also toward online publication but also, in part, because of the high 0.8 shown are the discrepancies between these values and the cost of printing and mailing the books. Nevertheless, as long as 1990 2000 2010 year improvement in the accuracy of the measurements. there is continuing demand and adequate resources, P hopes to continue the printed book. “Producing and updating the Review of Fig. 2. History of the PDG value of the charged B-meson mean Contributing knowledge Particle Physics in modern formats will remain Ps core mis- lifetime as quoted in the Review of Particle Physics. By and large, The published results collected in the Listings provide best values sion,” says eringer. history plots show a progression toward greater precision at and limits for a wide range of particle properties. The data can also Online access to Ps increasingly mobile-friendly web pages, central values quite consistent with the first data points shown. be used to study how knowledge in particle physics evolves, for or a P smartphone app with the complete contents of the Review example by plotting the evolution of PDG best values over time in a mobile-friendly format, could in principle replace the P UniBEaM25 Dual Axis Probe who grew up with the internet, not to care,” says Barnett. “We got (figure 2 and table). booklet. ut especially for students, the P book and booklet shown with quick clamp option it backwards. Everybody used the web, but more grad students and Over the decades there have been occasional disputes and dis- also carry substantial symbolic value, and the booklets are often postdocs found the printed book essential.” Their comments told crepancies for PDG staff to resolve. In one instance, discussions distributed in introductory particle-physics classes. “It is a land- why: to those entering physics, the book was not merely a reference escalated to a threatened lawsuit over PDG’s refusal to include mark thing for some of the graduate students and postdocs,” ar- but an introduction to the unexplored dimensions of their field. The one researcher’s particle data in the Review’s Summary Tables. nett remarks. “When you get your fi rst book, and when you see your distribution scheme for the print publications has become fairly There was also a case in which the experimental measurements of data appearing, you feel like you are a particle physicist.” sophisticated to minimise shipping costs. There are now four sepa- the mass squared of one particle (the electron neutrino) appeared rate distribution channels: in Switzerland, Japan, China and the as a negative number in the data: since this is mathematically ● rter reai US. Receiving the print materials is not automatic and recipients impossible, the PDG editors adjusted the error margins to account pdg.lbl.gov. must specifically request each new edition. The audience is largely for the problem. Another unusual episode concerned claims of e Roee Annal ee o Nlear ene physicists, teachers, students and physics fans, with most mailings discoveries of pentaquarks about a decade ago and later experi- rie rou n. s. going out to high-energy physics centres and academic institutions. ments discounting those earlier claims. These ups and downs, Roee Annal ee o Nlear ene The bulk of the funding for PDG comes from the Office of including the latest measurements from the LHCb experiment, Science of the DOE and supports the co-ordination and produc- were covered in the reviews to keep readers up to date. Rs tion activities at Berkeley Lab. Japan’s Ministry of Education, When various data are in substantial conflict, PDG sets error e ide de lnivers d physicien Culture, Sports, Science and Technology (MEXT) contributes to bars that range across the whole span of results, or, in some cases, these efforts via a US–Japan agreement on co-operative research provides no average at all. Also, about 20 years ago, the PDG insti- epis ans, les prors en physie des particles sont and development. CERN supports the meson team, and in recent tuted a new naming scheme that more logically renamed many par- compils dans n volme, Review of Particle Physics l sait de years CERN and the Institute of High Energy Physics of the Chi- ticles. All of them stuck except for one – there was an international la plication la pls cite en physie des particles a dernire Beam: H+, 150 keV, 170 nA. nese Academy of Sciences have paid for most of the printing campaign against that name-change, so the PDG staff deferred in dition de cet ovrae, parfois appel la ile de la physie des Software displays the beam inten- and shipping costs of books and booklets. Funding agencies in this one instance. particles , contient articles de synthse a section Particle sity distribution in the horizontal multiple countries, including INFN in Italy, MINECO in Spain, Only a subset of data col- istings comprend des valations de novelles mesres, and vertical planes, and calculates and IHEP in Russia provide travel and other support to PDG col- lected by PDG is available in a provenant de articles saot a mesres des ditions the beam location and integrated laborators in their countries. When you see your downloadable format suitable prcdentes es rdacters valent soinesement des donnes Until recently, the PDG group at Berkeley Lab was able to han- data appearing, you for further processing. There is portant sur environ 8 000 quantités différentes afi n de fournir des with total beam current. dle most of the PDG co-ordination tasks. But with the growth feel like you are a a demand for such access from moyennes, des astements et les meilleres limites eistantes of PDG in recent years, combined with a challenging funding particle physicist. researchers running Monte Cet ouvrage continue de s’étoffer et son histoire est le refl et d’un Priced to compete with environment, even this has become increasingly difficult. Thank- Carlo programs and others who domaine en constante voltion conventional wire scanners. fully, INFN recently agreed to help Berkeley Lab in this area. A want to, for example, investigate recent effort to streamline and automate many aspects of PDG’s the statistical properties of the le Rerts r Lawrence Berkeley National Laboratory wit operations is also providing necessary relief. agreement between multiple contributions by al ress www.d-pace.com [email protected]

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al a century ao teen einber pent te uer at ape o workin on a new teory o te tron interaction o pion By ctober 16 te iea a orpe into a teory o te weak an electroanetic interaction an te ollowin ont e publie a paper tat woul reolutionie our unertanin o te unaental orce

Weinberg’s paper “A Model of Leptons”, published in Physical today have grown up with the Standard Model’s orderly account Review etters (PRL) on 20 November , determined the direc- of the fundamental particles and interactions, but things were tion of high-energy particle physics through the fi nal decades of the very different in the 0s. uantum electrodynamics (ED) 20th century. Just two and a half pages long, it is one of the most had been well established as the description of the electromag- highly cited papers in the history of theoretical physics. Its contents netic interaction, but there were no mature theories are the core of the Standard Model of particles physics, of the strong and weak nuclear forces. By the 0s, now almost half a century old and still passing experimental discoveries showed that the weak force every experimental test. exhibits some common features with ED, in par- Most particle ticular that it might be mediated by a vector boson physicists analogous to the photon. Theoretical arguments also suggested that ED’s underlying “U()” group structure could be generalised to the larger group SU(2), but there was a serious problem with such a scheme: the W boson suspected to mediate the weak force would have to be very massive empirically, whereas the mathemati- cal symmetry of the theory reuired it to be massless like the photon. The importance of symmetries in understanding the fundamental forces was already becoming clear at the time, in particular how nature might hide its symmetries. Could “hidden symmetry” lead to a massive W boson while pre- serving the mathematical consistency of the theory It was arguably Wein- berg’s developments, in , that brought this concept to life.

trong inspiration Weinberg’s inspiration was an earlier idea of Nambu in which fermions – such as the proton or ▲ neutron – can behave like a

The fi rst page of Weinberg’s 1967 paper “A Model of Leptons”, published in Physical Review Letters.

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CCNov17_MOL.indd 25 04/10/2017 16:26 CERNCOURIER www. V o l u m e 5 7 N u m b e r 9 N o v e mber 2 0 1 7 CERN Courier November 2017 CERN Courier November 2017 Standard Model history Standard Model history Image credits: CERN Image credits: left- or right-handed screw as they move. If mass is ignored, these two “chiral” states act independently and the theory leads to the existence of a particle with properties similar to those of the pion – specifically a pseudoscalar, which means that it has no spin and its wavefunction changes sign under mirror symmetry. Nambu’s S Weinberg and M Veltman original investigations, however, had not examined how the three versions of the pion, with positive, negative or zero charge, shared their common “pion-ness” when interacting with one another. This commonality, or symmetry, is mathematically expressed by the group SU(2), which had been known in nuclear physics since the 1930s and in mathematics for much longer. It was this symmetry that Weinberg used as his point of depar- ture in building a theory of the strong force, where nucleons interact with pions of all charges and the proton and neutron them- selves form two “faces” of the underlying SU(2) structure. Empiri- cal observations of the interactions between pions and nucleons showed that the underlying symmetry of SU(2) tended to act on the left- or right-handed chiral possibilities independently. The mathematical structure of the resulting equations to describe this behaviour, as Weinberg discovered, is called SU(2)×SU(2). However, in nature this symmetry is not perfect because nucle- ons have mass. Had they been massless, they would have travelled at the speed of light, the left- and right-handed possibilities act- ing truly independently of one another and the symmetry left intact. That nucleons have a mass, so that the left and right states get mixed up when perceived by observers in different inertial frames, breaks the chiral symmetry. Nambu had investigated this effect as far back as 1959, but without the added richness of the SU(2)×SU(2) mathematical structure that Weinberg brought to the problem. Weinberg had been investigating this more sophis- ticated theory in around 1965, initially with considerable success. He derived theorems that explained the observed interactions of pions and nucleons at low energies, such as in nuclear physics. He CERN has been instrumental in proving the validity of Weinberg’s model of leptons. (Left) The first evidence for the weak neutral was able to predict how pions behaved when they scattered from current, recorded by the Gargamelle bubble-chamber experiment in July 1973, in which an incoming antineutrino knocks an one another and, with a few well-defined assumptions, paved the electron forwards (towards the left) to create a characteristic electronic shower with electron–positron pairs. (Top right) Direct way for a whole theory of hadronic physics at low energies. production for the first time of the W boson in the UA1 detector in late 1982, producing a high transverse energy electron (arrow). Meanwhile, in 1964, Brout and Englert, Higgs, Kibble, Gural- (Bottom right) An event display from the ATLAS experiment showing a candidate event for a Higgs boson decaying into four nik and Hagen had demonstrated that the vector bosons of a electrons, recorded a few weeks before the official Higgs discovery was announced on 4 July 2012. Yang–Mills theory (one that is like QED but where attributes such as electric charge can be exchanged by the vector bosons Epiphany on the road help establish these constituents were a year away from announcing themselves) put forward a decade earlier could become massive In the middle of September 1967, while driving his red Camaro to their results, and Bjorken’s ideas of a quark model, articulated at con- without spoiling the fundamental gauge symmetry. This “mass- work at MIT, Weinberg realised that he had been applying the right ferences that summer, were not yet widely accepted either. Finally, generating mechanism” suggested that a complete Yang–Mills ideas to the wrong problem. Instead of the strong interactions, for with only three flavours of quark, Weinberg’s ideas would lead to theory of the strong interaction might be possible. In addition to which the SU(2)×SU(2) idea refused to work, the massless photon empirically unwanted “strangeness-changing neutral currents”. All the well-known pion, examples of massive vector particles that and the hypothetical massive W boson of the electromagnetic and these problems would eventually be solved, but in 1967 Weinberg feel the strong force had already been found, notably the rho- weak interactions fitted perfectly with this picture. To call this pos- made a wise choice to focus on leptons and leave quarks well alone. meson. Like the pion, this too occurs in three charged varieties: sibility “hypothetical” hardly does justice to the time: the W boson Following the discovery of parity violation in the 1950s, it was The cover page (top) and references (above) of Weinberg’s positive, negative and zero. Superficially these rho-mesons had was not discovered until 1984, and in 1967 was so disregarded as to clear that the electron can spin like a left- or right-handed screw, original manuscript, as given to H P Durr at the time of the the hallmarks of being the gauge bosons of the strong interac- receive at best a passing mention, if any, in textbooks. whereas the massless neutrino is only left-handed. The left–right 1967 Solvay conference, may be compared with the paper in tions, but they also have mass. Was the strong interaction the Weinberg needed a concrete model to illustrate his general idea. symmetry, which had been a feature of the strong interaction, was published form. The origin of the arrow on the manuscript theatre for applying the mass-generating mechanism? The numerous strongly interacting hadrons that had been discovered gone. Instead of two SU(2), the mathematics now only needed one, adjacent to reference three is unknown, but may be a reminder Despite at first seeming so promising, the idea failed to fit the in the 1950s and 1960s were, for him, a quagmire, so he restricted his the second being replaced by the unitary group U(1). So Wein- to complete that reference: the citations of Brout and Englert data. For some phenomena, the SU(2)×SU(2) symmetry empiri- attention to the electron and neutrino. Here too it is worth recalling berg set up the equations of SU(2)×U(1) – the same structure that, and to “Hagen et al.” (Guralnik Hagen and Kibble) have been cally is broken, but for others where spin didn’t matter it works the state of knowledge at the time. The constituent quark model with unknown to him, had been proposed by Sheldon Glashow in 1961 added later, possibly following discussions at that meeting. perfectly. When these patterns were incorporated into the maths, three flavours – up, down and strange – had been formulated in 1964, and by Abdus Salam and John Ward in 1964 in attempts to marry s the rho-meson stubbornly remained massless, contrary to reality. but was widely disregarded. The experiments at SLAC that would the electromagnetic and weak interactions. His theory, like

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Private collection He begins the final paragraph with a question: “Is this model renor- Weinberg’s 1967 achievement is rooted in the notation of group theory, malisable?” The extent of his intuition is revealed in his argument: which is the mathematical language describing the symmetries of a although the presence of a massive vector boson hitherto had been system, and built upon many earlier successes including that of quantum a scourge, the theory with which he had begun had no such mass electrodynamics (QED). QED is perhaps the simplest example of a general and, as such, was “probably renormalisable”. So, he pondered: “The class of “non-abelian gauge theories”. Since the all-important electric question is whether this renormalisablity is lost [by the spontaneous charge in QED is a single number, it can be described mathematically breaking of the symmetry].” And the conclusion: “If this model is in terms of the first unitary group, U(1). In the 1950s Yang and Mills renormalisable, what happens when we extend it…to the hadrons?” constructed generalisations of QED in which the U(1) number was replaced By speculating that his model may be renormalisable, Weinberg by matrices, such as in the groups SU(2) or SU(3). The weak force exhibited was hugely prescient, as ’t Hooft and Veltman would prove four tantalising hints that a SU(2) generalisation of QED might be involved, but years later. And perhaps it was a chance encounter at the Solvay there was a serious problem: a “W boson” – the analogue of QED’s photon Congress in Belgium two weeks before his paper was submitted – would have to be very massive empirically, whereas the mathematical that helped convince Weinberg that he was on the right track. symmetry of the theory required it to be massless – like the photon. The only way to give the W and Z particles mass yet leave the photon massless was if Weinberg at his blackboard. Weinberg in Stockholm in 1979 receiving the Nobel Prize in Solvay secrets nature contained “hidden symmetries” that were somehow broken. Physics from the king of Sweden. The prize was shared between By the end of September 1967, Weinberg had his ideas in place as In 1961 Goldstone discovered a theorem suggesting, inter alia, that – could hide this property in empirically consistent ways when particles him, Sheldon Glashow and Abdus Salam “for their he set off to Belgium to attend the 14th Solvay Congress on Funda- a theory of the weak force involving hidden symmetry is impossible. become massive; that there should be a massive boson without spin (the contributions to the theory of the unified weak and mental Problems in Elementary Particle Physics, held in Brussels However, in 1963, condensed-matter theorist Philip Anderson pointed Higgs boson); and that the W boson could also gain mass while preserving electromagnetic interaction between elementary particles, from 2 to 7 October. He did not speak about his forthcoming paper, out that superconductivity manages to evade Goldstone’s theorem, the underlying mathematical symmetry of the theory. It was Weinberg’s including, inter alia, the prediction of the weak neutral current”. but did make some remarks after other talks, in particular follow- and demonstrated this mathematically in a theory without relativity. 1967 paper that brought all of these pieces together, and today we know that ing a presentation by Hans Peter Durr about a theorem of Jeffrey The following year several theorists, including Peter Higgs, generalised nature follows this path, with the weak and electromagnetic interactions theirs, required two massive electrically charged bosons – the W+ Goldstone and spontaneous symmetry breaking. During a general Anderson’s insights to include relativity. Among the implications were that described by a single SU(2)×U(1) structure. At the time, however, the and W– carriers of the weak force – and two neutral bosons: the discussion session following Durr’s talk, Weinberg mused: “This a theory involving fermions with no mass – with so-called chiral symmetry breakthrough was hardly noticed. massless photon and a massive Z0. If correct, it would show that the raises a question I can’t answer: are such models renormalisable?” electromagnetic and weak forces are unified, taking physics a step He continued with a similar argument to that which later appeared closer to the goal of a single theory of all fundamental interactions. in his paper, ending with: “I hope someone will be able to find out Lasting impact This episode in particle physics is not only one of the seminal “The history of attempts to unify weak and electromagnetic whether or not [this] is a renormalisable theory of weak and elec- Weinberg’s genius was to assemble together the various pieces of breakthroughs in our understanding of the physical world, but interactions is very long, and will not be reviewed here.” So began tromagnetic interactions.” a jigsaw and display the whole picture. The basic idea of mass gen- touches on the profound link between mathematics and nature. On the first footnote in Steven Weinberg’s seminal November 1967 There was remarkably little reaction to Weinberg’s remarks, eration was due to the assorted theorists mentioned above, in the one hand it shows how it is easier to be Beethoven or Shakespeare paper, which led to him being awarded the 1979 Nobel Prize in and he himself has recalled “a general lack of interest”. The only summer of 1964. However, a crucial feature of Weinberg’s model than to be Steven Weinberg: change a few notes in a symphony or Physics with Salam and Glashow. Weinberg’s footnote mentioned recorded statement came from François Englert, who insisted that was the trick of being able to give masses to the W and Z while a phrase in a play, and you can still have a wonderful work of art; Fermi’s primitive idea for unification in 1934, and also the model the theory is renormalisable; then, remarkably, there is no further leaving the photon massless. This extension of the mass-generating change a few symbols in Weinberg’s equations and the edifice falls that Glashow proposed in 1961. discussion. Englert and Robert Brout, then relatively junior scien- mechanism was due to Tom Kibble, in 1967, which Weinberg rec- apart – for if nature does not read your creation, however beautiful tists, had both attended the same Brussels meeting. ognises and credits. it might be, its use for science is diminished. Like all great theo- Clarity of thought At some point during the Solvay conference, Weinberg presented a As was the case with his comments in Brussels the previous rists, Weinberg revealed a new aspect of reality by writing symbols Weinberg started his paper by articulating the challenge of unify- hand-written draft of his paper to Durr, and 40 years later I obtained month, Weinberg’s paper appeared in November 1967 to a deaf- on a sheet of paper and manipulating them according to the logic of ing the electroweak forces as both an opportunity and a threat. He a copy by a roundabout route. Weinberg himself had not seen it in ening silence. “Rarely has so great an accomplishment been so mathematics. It took decades of technological progress to enable focused on the leptons – those fermions, such as the electron and all that time, and thought that all record of his Nobel-winning manu- widely ignored,” wrote Sidney Coleman in Science in 1979. Today, the discoveries of W and Higgs bosons and other entities that were neutrino, which do not feel the strong force. “Leptons interact only script had been lost. The original manuscript is notable for there Weinberg’s paper has been cited more than 10,000 times. Hav- already “known” to mathematics 50 years ago. with photons, and with the [weak] bosons that presumably mediate being no sign of second thoughts, or editing, which suggests that it ing been cited but twice in the four years from 1967 to 1971, sud- ● This article draws on material from Frank Close’s history of the weak interactions. What could be more natural than to unite these was a provisional final draft of an idea that had been worked through denly it became so important that researchers have cited it three path to discovery of the Higgs boson: The Infinity Puzzle (Oxford spin-one bosons [the photon and the weak bosons] into a multiplet,” in the preceding days. The only hint of modification after the first times every week throughout half a century. There is no parallel University Press). he pondered. That was the opportunity. The threat was that “stand- draft had been written is a memo squeezed in at the end of a reference for this in the history of particle physics. The reason is that in 1971 ing in the way of this synthesis are the obvious differences in the to Higgs, to include references to Brout and Engler t, and to Guralnik, an event took place that has defined the direction of the field ever Résumé masses of the photon and [weak] boson.” Hagen and Kibble, for the idea of spontaneous symmetry breaking, since: Gerard ’t Hooft made his debut, and he and Martinus Velt- Naissance d’une symétrie Weinberg then suggests a solution: perhaps “the symmetries on which the paper was based. Weinberg’s intuition about the renor- man demonstrated the renormalisability of spontaneously broken relating the weak and electromagnetic interactions are exact [at malisability of the model is already present in this manuscript, and Yang–Mills theories. A decade later the W and Z bosons were Il y a un demi-siècle, Steven Weinberg, lors d’un été à Cape Cod, a fundamental level] but are [hidden in practice]”. He then draws is identical to what appears in his PRL paper. There is no mention of discovered by experiments at CERN’s Super Proton Synchrotron. travaillait sur une nouvelle thérie de l’interaction forte des pions. attention to the ideas of Higgs, Brout, Englert, Guralnik, Hagen Glashow’s SU(2)×U(1) model in the draft, but this is included in the A further 30 years were to pass before the discovery of the Higgs En octobre 1967, l’idée devient une théorie des interactions faible et and Kibble, and uses these to give masses to the W and Z in his version that was published in PRL the following month. This is the boson at the Large Hadron Collider completed the electroweak électromagnétique, et le mois suivant il publie un article qui allait model. In a further important insight, Weinberg shows how this only substantial difference. This manuscript was submitted to the menu. And in the meantime, completing the Standard Model, révolutionner notre connaissance des forces fondamentales. symmetry-breaking mechanism leaves the photon massless. editors of PRL on Weinberg’s return to the US, and received by them quantum chromodynamics was established as the theory of the His opening paragraph ended with the prescient observation that: on 17 October. It appeared in print on 20 November. strong interactions, based on the group SU(3). Frank Close, University of Oxford.

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Under our brand TTL Professional®, we produce a wide range of computers, laptops, ultralight laptops, lightweight terminals, servers, storage Theorist Steven Weinberg talks about his predictions to be taken very seriously”. arrays and graphic workstations, all with the Needless to say, Weinberg is delighted to have been able to wit- latest technology. We also create virtualization seminal 1967 work and reflects on the status ness the validation of the Standard Model (SM) over the decades. software, operating systems and personalized “I mean, it’s what keeps you going as a theoretical physicist to hope audiovisuals solutions. Our products are constantly of the field now that all the particles on the that one of your squiggles will turn out to describe reality,” he evolving under the supervision and monitoring electroweak menu have been discovered. says. “I wouldn’t have been surprised or even very chagrined that, of our Engineering and Networking laboratory, although the general idea was right, this particular model didn’t wich manages I+D+i projects. This department is, describe nature.” without a doubt, the cornerstone of all our Today, 50 years after his 1967 insight, Weinberg protests the projects and technological solutions. Steven Weinberg was 34 when he produced his iconic “Model of notion that he is retired. The US has laws against discrimination Leptons”. The paper marked a moment of clarity in the history of on the basis of age, he says dryly. “I tell the people here that I plan particle physics and gave rise to the electroweak Standard Model, to retire shortly after I die.” He is currently teaching a course in but it was also exceptional in inspiring one of the biggest experi- astrophysics at the University of Texas at Austin, his base for the mental programmes science has ever seen. Flushing out and meas- past 35 years, and has two books and a new cosmology paper in the uring its predicted W, Z and Higgs bosons took a multi-billion pipeline. Weinberg spoke to the Courier by phone in September www.teknoservice.es Swiss-franc effort in Europe that spanned four major projects – from his home, reflecting on the state of high-energy physics fol- Gargamelle, the SPS, LEP and the LHC – and defined CERN’s lowing the Higgs boson discovery and on where the best hopes for research programme, keeping experimentalists in gainful employ- new physics might lie. He began by recounting the thought pro-

ment for at least four decades. Not bad for a theory that, as Wein- cesses that led him to his seminal 1967 work – many of which tooks berg wrote at the time, “has too many arbitrary features for [its] place in children’s playgrounds.

Steven Weinberg photographed at the University of Texas at Austin in late September 2017. (All image credits: Matt Valentine.)

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Park-bench physics Renormalisability was the technique that connected quantum Unlike many particle physicists on the day of the Higgs “It was a complicated time of my life because my family had field theory to reality, offering a scientifically sound way to deal announcement on 4 July 2012, Weinberg doesn’t recall exactly moved to Cambridge from Berkeley while my wife was studying with the infinities that arise in calculations. Back when his paper what he was doing when he heard the news. What he is sure of is at Harvard for her law degree. I had all the responsibility of taking was published, however, Weinberg did not know if his theory was that we are entering what he described several years ago as the care of our four-year old daughter, including taking her to nursery renormalisable. That was probably why nobody took much notice “nightmare scenario” of having found a SM Higgs boson and noth- school, and a lot of my thinking was done while sitting on park of it, he says. “Remember: when we’re talking about renormalis- ing else. He says we’ve gotten ourselves into a rather unfortunate benches and watching my daughter play,” he says. ability, it’s not just something theorists do to get rid of infinities. It situation because the SM describes all the physics that can be Weinberg did not set out to unify the forces. He had been was a criterion that was the sort you look for in theoretical phys- addressed experimentally except things outside the SM like grav- applying his ideas about symmetries, specifically the structure ics, that defines a certain type of simplicity in your theories which ity and the neutrino masses. “It’s nobody’s fault. It is not an intel- SU(2)×SU(2), to the strong interaction but it implied that the rho otherwise would be arbitrary. We’re talking about whether we can lectual failure. It’s just a fix we’ve got into.” He doesn’t hold out too meson would be massless, contrary to experiment. “When I had have a theory of the weak interaction in which we can calculate much hope in mainstream theoretical arguments for the existence the idea that the massless rho meson might really be the photon, beyond the lowest order in perturbation theory.” Weinberg strongly of physics beyond the SM at the energies currently being probed it became natural to me that the rest of this gauge theory, suitably suspected his might be such a theory because before spontaneous at the LHC – i.e. that new heavy particles must exist to cancel out modified, could only be a theory of weak forces.” The work went symmetry breaking is taken into account, it has the same form quantum contributions to the Higgs mass that would cause it to quickly once he realised what he was doing. “You take the left- as QED and it had already been proved that non-spontaneously spiral to infinity. The fact that we now know that an elementary handed electron plus neutrino doublet and right-handed electron broken Yang–Mills theories were renormalisable. “Salam and I Higgs scalar exists makes this “hierarchy problem” somewhat and ask what the most general possible symmetry group is, which weren’t sure but we didn’t think spontaneous symmetry breaking harder, Weinberg concedes, but he points out that we’ve been liv- turns out to be SU(2)×U(1)×U(1). Then you throw one U(1) away would affect the renormalisability because if you go to very high ing with the problem already for 40 years. So far the LHC has because if that was an unbroken gauge symmetry, you would have energies (much larger than the W or Z mass), the fact the sym- not found evidence for physics beyond the SM, including the most long-range forces among electrons which you don’t observe. So metry is broken is no longer significant.” Had he not thought the popular solution to shield the Higgs from getting additional mass: you’re led almost inevitably towards SU(2)×U(1). Indeed, though model renormalisable, he might not have published. “The prospect supersymmetry (SUSY). “Worse, there isn’t any one completely at first I didn’t know it, the same group had been used in a different of issuing an erratum was too much!” satisfactory SUSY model. Every SUSY model has things in it that way earlier by Glashow and by Salam and Ward.” In 1971, Weinberg began to realise that his paper was “hot stuff”, are troublesome,” says Weinberg. The paper was published without fanfare in Physical Review following the critical breakthrough by ’t Hooft and Veltman prov- He thinks we might have to find other explanations for this and Letters on 20 November within a month of its submission. Wein- ing that the theory was renormalisable, although whether or not other absurdly fine-tuned parameters in the universe, such as the berg doesn’t recall any talk he gave before the publication. He men- his particular model of leptons was correct was a still matter for very small value of the vacuum energy or cosmological constant, tioned it in a side comment at the Solvay conference around that experiment. The same year, he also tried to extend his ideas to the or even abandon traditional explanations altogether. time (see p25), but it didn’t arouse tremendous excitement. strong interactions using the quark model, in which there was little “No one has come up with a plausible suggestion there except for In many ways, the paper was uncharacteristic of Weinberg. His confidence at the time. The reality of quarks became clear with the somewhat desperate suggestion that it is anthropic – that you tendency was to write general papers without worrying too much the discovery by Gross and Wilczek and Politzer in 1973 of the Higgs boson. “The discovery of the Higgs boson was very important have a multiverse and by accident there are occasional sub-universes about their specific realisation in nature, he says, but in this one he asymptotic freedom of some gauge theories, and the subsequent because it confirmed the very simple early picture of spontaneous where the vacuum energy is small and it’s only those in which gal- was more specific. “Of course, experimentalists don’t test general development of quantum chromodynamics, to which Weinberg, symmetry breaking, which we couldn’t have known was correct axies can form – and people have suggested similar anthropic ideas, so I was delighted when they showed that my theory was the along with Gross and Wilczek, contributed the idea that it is impos- because there were alternatives,” he says. arguments for the smallness of the Higgs mass and the quark-mass right one. And then, after the neutral-currents discovery, the W and sible to isolate coloured particles such as quarks and gluons. So did Weinberg’s 1967 paper also predict the Higgs boson? “It hierarchy,” says Weinberg, who himself used anthropic reasoning Z were discovered directly at CERN 10 years later and measured “It’s funny you know, people look back at the 1970s as one of the depends, as Bill Clinton might say, what is meant by the word ‘the’,” in the 1980s to estimate, correctly, the approximate value of the cos- in detail at LEP and SLAC.” most miserable peacetime decades in the 20th century, as there he laughs. “Is it the Higgs boson? Well, the existence of these par- mological constant a decade before it was inferred observationally It was not the specific model of leptons that excited him, though. was lots of unemployment and high inflation, in the US at least,” ticles in the general class of spontaneously broken gauge theories from the velocities of distant supernovae. It’s a depressing kind of Since his graduate days at Princeton, Weinberg has been hooked he muses. “But for us physicists it was a great time: everything was was predicted by Higgs and so on, and if you included theories that solution to the problem, he accepts. “But as I’ve said: there are many on the possibility of having a deductive basis for a physical theory coming together, and experimentalists and theorists were talking are non-gauge invariant then even earlier by Goldstone. But if by conditions that we impose on the laws of nature such as logical con- following from the principles of symmetry and, in particular, renor- to each other in lots of ways. Things are much harder today.” ‘the’ you mean the particle discovered, then that was predicted in sistency, but we don’t have the right to impose the condition that the malisability. “Symmetry is not enough by itself. In electromagne- my paper. The first paper that made a specific prediction of a single laws should be such that they make us happy!” tism, for example, if you write The Higgs nightmare neutral particle whose coupling to leptons and later also to quarks Weinberg’s outlook on the field today is pretty much as it was in down all the symmetries we The discovery of the Higgs boson by the ATLAS and CMS experi- was proportional to their masses was the 1967 model of leptons. 1979 when he gave his Nobel-prize lecture. The only big difference know, such as Lorentz invari- ments at CERN five years ago was the capstone in Weinberg’s model. The others also had a scalar par ticle but they were not developing a would be string theory, he says, which hadn’t yet come along as a Science is not ance and gauge invariance, you Until then, no one knew for sure how the electroweak symmetry gets theory of weak interactions, they were considering several classes possible theory of everything. “Apart from that, I said about the the experience of don’t get a unique theory that broken to give elementary particles their masses – it was still possible of theories with leftover scalars with unknown properties.” future beyond the SM that I think it’s unfortunate that there isn’t a just one scientist predicts the magnetic moment that the Higgs mechanism was correct but that it does not involve a Weinberg thinks the Nobel-prize committee made an “excellent clear idea to break into it.” Even the discovery of neutrino masses, of the electron. The only way to Higgs boson, for instance, or that the “Higgs” is a composite particle job” in deciding who would share in the 2013 prize for the discov- inferred from the observation of neutrino oscillations 20 years ago, but of the whole do that is to add the principle of bound by new strong forces that lead to a dynamical breakdown ery (François Englert and Peter Higgs). “It isn’t a prize for predict- does not threaten the SM, he says. On the contrary: neutrino masses community renormalisability – which dic- of the symmetry. Precisely such a model, called technicolour, was ing the Higgs boson, it is a prize for the theoretical discovery of the are what you expect. extending back tates a high degree of simplicity proposed by Weinberg and Susskind in 1979. Back in 1967, though, Higgs mechanism, which is exactly right because that is what was in the theory and excludes these Weinberg took the simplest possibility: a doublet of scalars. It was proposed by those 1964 papers. I rediscovered it in 1967 because I Neutrinos and new physics to antiquity. additional terms that would have the only kind of elementary field that could not only give mass to was working on spontaneously broken SU(2)×SU(2) gauge theory By the time Weinberg received his Nobel prize in late 1979, he changed the magnetic moment the W and the Z but also the electron, he reasoned, and it would for the strong interaction, but I take no credit for it because it was had arrived at a more nuanced interpretation of field theory and of the electron from the value lead to the necessary existence of a leftover scalar particle that was already in the literature for three years. The actual Higgs boson, I described it in a paper titled “Phenomenological Lagrangians”. s Schwinger calculated in 1948.” not eliminated by the Higgs mechanism and became known as the think that was an experimental achievement.” Building on the work of others, such as Schwinger, it presented the

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SM as the leading term in an “effective” field theory that is merely opening up a whole area of astronomy.” Cosmology, along with the Three Minutes, which has been translated into 22 languages and for a low-energy manifestation of a deeper microscopic theory that we foundational issues of quantum mechanics, is the subject of Wein- which he still receives royalty cheques, he intends to go on writing. are yet to uncover. In this more modern view, field theories don’t have berg’s own recent work, and he is currently putting together a paper He has a contract with Cambridge University Press to publish a new to be renormalisable to be logically consistent but can contain, in with co-worker Raphael Flaugera on the effect of the intergalactic book called Lectures on Astrophysics based on his current teaching addition to the renormalisable terms, a slew of non-renormalisable medium on gravitational waves from distance sources. activities and is bringing out a third collection of popular essays with terms that are suppressed by negative powers of some very large Harvard University Press, with a fourth planned. mass (corresponding to the scale at which the true theory applies). Reflecting on physics For neutrinos, treating the SM as an effective field theory has It is beyond doubt that Weinberg’s 1967 paper was game-changing, The last three minutes major implications. Whereas simply inserting neutrino masses but does he himself rate it as his most important contribution to Steven Weinberg’s career – from his undergraduate days at Cornell, into the theory would violate the SU(2)×U(1) symmetry, Wein- physics? “Oh I don’t know. I don’t like praising my own papers. graduate studies in Princeton, and subsequent positions at Colum- berg realised that there is an interaction between leptons and the The 1967 paper was part of a programme of many decades – a con- bia, Berkeley, Harvard, MIT and Texas – is one that any physicist Higgs doublet that avoids this. Crucially, since the interaction is cern with symmetries, especially broken ones – which went back would aspire to. His name will always be associated with our fun- non-renormalisable, it is suppressed by a very large-mass denomi- to the early 1960s, at least to my paper with Goldstone and Salam damental understanding of the universe, and you get the feeling nator – explaining both the existence of neutrino masses and their raising the issue of massless Goldstone bosons, after which Higgs that none of it ever felt much like “work” in the usual sense. “The smallnesses and giving rise to what is more generally called the et al. showed us how to avoid them. I guess mine was a key paper physics career, quite apart from what you do in physics day to day, seesaw mechanism. in that department, but I had been working on broken symmetries has given me the opportunity to know a lot of interesting people “In a sense it is beyond the SM, but I would rather say it is beyond in the context of strong interactions for a decade. Then there is the and to visit different countries not as a tourist but as a co-worker,” the leading terms – the renormalisable, unsuppressed part of the development of effective theories, which is not so much a theory he says. “It’s such a delight to talk to fellow physicists and to work- SM,” says Weinberg. “But hell – so is gravity! The symmetries of but a point of view.” What he prizes above all else, however, is not up a paper based on a common understanding, and to at the same general relativity don’t allow any renormalisable interactions of embodied in any single paper or certainly not in any single model: time transcend national boundaries. I like that so much.” Not that massless spin-2 particles called gravitons. We know about gravity next big-ticket collider experiment should be: an electron–positron it is about changing the point of view of physicists. he has collaborated that much: as with “A Model of Leptons”, most even though it’s incredibly strongly suppressed only because it has collider, which potentially comes in straight or circular varieties, or “I prized the 1967 paper programmatically because it exemplified of his 350 or so papers have been “one-man jobs”. this property of adding up: every atom in the Earth attracts a falling a more energetic hadron collider. Most of the options on the table the need to look for a renormalisable theory based on symmetries Yet Weinberg is not your stereotypical lost-in-his-work genius body, always pulling in the same direction. If it wasn’t for that fact, have precision measurements of the Higgs boson as part of their that are spontaneously broken, and by god it turned out to be the right who locks himself away for long periods to work on a problem. His we wouldn’t know about its existence from experiments – certainly physics cases. model!” From the start, he knew his model of leptons was the kind best ideas don’t come to him while he’s working at all. He recalls not at experiments at the LHC.” Of course, neutrinos were still of theory that looked right, but it doesn’t just take a certain mind to one day he came out of the shower and exclaimed to his wife that he thought massless back in 1979. Weinberg does not take credit for Next steps for the field be able to see such truths, he explains. It takes a lot of minds over a had figured out why the cosmological constant is so small (at a time predicting neutrino masses, but he thinks it’s the right interpre- Weinberg says he doesn’t have an educated opinion on which long period. Weinberg illustrates the process with the example of before he had started thinking about anthropic explanations). “Then tation. What’s more, he says, the non-renormalisable interaction machine should come next. “It hinges partly on what the experi- chicken sexing. It is important in the poultry business to be able to the next day I came out and I said [deep voice] ‘no’! So ideas come that produces the neutrino masses is probably also accompanied mentalists can actually accomplish, and I’m not equipped to judge determine the sex of newborn chicks, he says, and there was a school to you all the time and most of them are no good, and every once in with non-renormalisable interactions that produce proton decay that. And it hinges also on what the new physics is, and I’m not that taught the science of chicken sexing by giving people a newborn a while you find one that is good and you have fun working at your and other things that haven’t been observed, such as violation of equipped to judge that!” he says. “If I had a very specific proposal chick and asking them to say whether it was male of female: if they desk. Getting good ideas isn’t something you get by trying hard, but baryon-number conservations. “We don’t know anything about the for beyond-the-SM then it might indicate in which of these direc- guessed wrong, they would receive some sort of punishment, while if by thinking a lot about what problems bother you. But that doesn’t details of those terms, but I’ll swear they are there.” tions we should go, but I don’t know of any proposal that is attrac- they guessed right they got some kind of reward. After repeating the always work either – just think of my ruined summer in 1972!” As to what is the true high-energy theory of elementary particles, tive enough to go one way or the other.” Although he would like to process hundreds of times, people began to guess correctly. “We’ve He never works in his office. His research work has always been Weinberg says string theory is still the best hope we have. “I am see the Higgs, the first scalar particle discovered, measured in more learned that, just as feeling the underside of a newborn chicken you done at home, where he and his wife have separate offices down the glad people are working on string theory and trying to explore it, detail, he fears that it will just confirm the simplest picture of the might learn what distinguishes a male from a female, science is hall from one another and interrupt one another frequently. “I’m not although I notice that the smart guys such as Witten seem to have Higgs mechanism. “Because that’s what you get if you insist on a not the experience of just one scientist but of the whole commu- hard to interrupt. I have a television set on my desk which I keep on turned their attention to solid-state physics lately. Maybe that’s a renormalisable theory, and I think it’s correct to do so for reasons I nity extending back to antiquity, which has gradually beaten into us while I work, typically watching an old movie, because I find work sign that they are giving up, but I hope not.” Weinberg worked on was beginning to understand in 1979.” which theory is beautiful and which is likely to be right.” in theoretical physics so far removed from normal affairs.” Doesn’t strings himself in the late 1980s, writing a couple of papers “of He is glad that CER N is continuing with the LHC, and that the US is Asked what single mystery, if he could choose, he would like to it distract him? “But I need the distraction to keep at my desk because stunning unimportance”, but decided not to devote his career to doing neutrino-oscillation experiments, “which seems to now be the see solved in his lifetime, Weinberg doesn’t have to think for long: the actual work is so, well…it’s so chillingly non-human. I need to it. As is documented in his 1992 book Dreams of a Final Theory, American style having given up on the SSC”. Another topic he thinks he wants to be able to explain the observed pattern of quark and feel that I am still part of the human race while I’m doing it.” and much earlier in his Nobel lecture, he has his own hunch about should be pushed more is the search for baryon non-conservation lepton masses. In the summer of 1972, when the SM was coming an ultimate microscopic theory of nature, rooted in an idea called (proton decay) on Earth. But the most promising arena for progress together, he set himself the task of figuring it out but couldn’t Résumé “asymptotic safety”. Weinberg also still holds hope that one day these days is astronomy, he says. come up with anything. “It was the worst summer of my life! I Le physicien et le Modèle a paper posted in the arXiv preprint server by some previously After all, otherwise we wouldn’t mean, obviously there are broader questions such as: why is there unknown graduate student will turn the SM on its head – a 21st cen- even dream of the existence of something rather than nothing? But if you ask for a very specific La découverte du boson de Higgs, en confirmant que la symétrie tury model of particles “that incorporates dark matter and dark It is not an dark matter and dark energy, and question, that’s the one. And I’m no closer now to answering it électrofaible est brisée de la manière la plus simple possible, a energy and has all the hallmarks of being a correct theory, using intellectual failure. it’s an area where experiment is than I was in the summer of 1972,” he says, still audibly irritated. été une consécration pour la théorie proposée par S. Weinberg en ideas no one had thought of before”. It’s just a fix we’ve still very fruitful – as evidenced He also doesn’t want to die without knowing what dark matter is. 1967. Le Courier a pu s’entretenir par téléphone avec cet éminent Until that day comes, particle physicists have to be content with by the recent discovery of gravi- There are all kinds of frustrations, he says. “But how could it be physicien. Il nous a parlé des conséquences de la découverte du scouring the TeV energy scale at the LHC for new particles and got into. tational waves. “My goodness, otherwise? I am enjoying what I am doing and I have had a good boson de Higgs et de ce que nous pouvons faire pour avancer encore with subjecting the SM to increasingly precise tests – not just at the that’s the most exciting thing run, and I have a few more years. We’re having a total eclipse here dans notre connaissance des champs et des particules élémentaires. LHC but at numerous other experiments at CERN and beyond. The – studying gravitational radia- in April 2024 and I look forward to seeing that.” field also faces a critical decision in the next few years as to what the tion not just for its own sake but Forty years after the publication of his famous book The First Matthew Chalmers, CERN.

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A ppointments

• Mu Metal Brazing CERN Council elects European-strategy secretary

• Vacuum Brazing At the 186th session of CERN Council, which Experimentalist Halina Abramowicz, took place at CERN on 25–29 September, A Levy secretary of the European Strategy Group. • Vacuum Hardening experimental particle physicist Halina Abramowicz of Tel Aviv University in Israel to forward detectors for future linear was appointed secretary of the European colliders. She completed her undergraduate • Vacuum Annealing Strategy Group. This marks the official start and postgraduate degrees at Warsaw of the next update of the European Strategy University in Poland in the 1970s, and also • Vacuum Stress Relieving for Particle Physics, which will reach a worked on the former experiments ZEUS conclusion in May 2020, with Abramowicz’s and CDHSW. “The strategy update is a very • Solution Treatment & first task being to develop the timeline and a important task in preparing the future of detailed plan. our field,” said CERN Director-General Precipitation Hardening Abramowicz works on the ATLAS Fabiola Gianotti. “We need everybody’s experiment, specialising in perturbative contribution to ensure that we have a • Collection & Delivery Service and non-perturbative QCD, and is also a strategy that truly reflects the wishes of the mslheattreatment.co.uk member of the FCAL collaboration devoted field.” MSL Heat Treatment A w A r d s Hunters Lodge | Balcombe Road | Horley | Surrey | RH6 9SJ | England Nobel recognition for discovery of gravitational waves Tel : +44 (0) 1293 822660 Fax : +44 (0) 1293 822661 Email: [email protected] Part of the Magnetic Shields Group The 2017 Nobel Prize in Physics has been LIGO story, Ronald Drever, passed away awarded to Rainer Weiss, Barry Barish in March this year. He had already shared, and Kip Thorne of the LIGO/Virgo along with Weiss and Thorne, in the 2016 collaboration “for decisive contributions to Breakthrough prize, Gruber Cosmology the LIGO detector and the observation of Prize and the Kavli Prize in Astrophysics. gravitational waves”. Weiss, of MIT, shares The recognition by the Nobel committee half the SEK 9 million award, while his for physics comes less than two years after Caltech colleagues Barish and Thorne share the LIGO/Virgo collaborations announced the other half. the first direct detection of gravitational More than 40 years ago, Thorne and Weiss Rainer Weiss, Barry Barish and Kip Thorne waves in February 2016, followed by a pioneered the idea that gravitational waves brought to fruition a 40-year long research second event a few months later and a third could be detected, in particular using large programme. announced in June this year. A fourth • Mu Metal Sheet Supply laser interferometers that would measure gravitational-wave signal was revealed just distortions in space–time induced by a from a small R&D project, the trio ensured last month. These and further events open • Magnetic Shield Manufacture passing gravitational wave. Together with that the search for gravitational waves would a brand new view of the universe (CERN Barish, who led the transformation of LIGO end in success. A fourth key figure in the Courier January/February 2017 p34). • Hydrogen Annealing • Metal Spinning IEEE applied-superconductivity award The IEEE Award for Continuing and CERN’s Luca Bottura receives his award. • 5 Axis Machining Significant Contributions in the Field of Large Scale Applied Superconductivity selected for developing computer models for • Magnetic Simulation & Test was presented to CERN’s Luca Bottura J Ordan/CERN the design and analysis of cable-in-conduit during the European Conference on superconductors, measuring the field of • CAD Design & Specification Applied Superconductivity (EUCAS) on the LHC’s superconducting magnets and 18 September in Geneva, Switzerland. The developing a parametric field model for the magneticshields.co.uk award recognises outstanding technical LHC operation, leading the development contributions and achievements in the field of advanced superconducting magnets for of applied superconductivity and comprises future accelerator projects, and promoting a plaque, an inscribed medallion, and a cash superconducting technology internationally Magnetic Shields Limited award of US$5000. through technical editorship, scientific Headcorn Road | Staplehurst | Tonbridge| Kent | TN12 0DS | England Bottura, who is head of CERN’s magnets, networking, and the organisation of superconductors and cryostats group, was scientific events. Tel : +44 (0) 1580 891521 Fax : +44 (0) 1580 893345 Email: [email protected] Part of the Magnetic Shields Group 37

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FAST SDD® J Ordan/CERN DOE names top 40 breakthroughs On 19 September, CERN Director- Count Rate = >1,000,000 CPS General Fabiola Gianotti delivered a public lecture at the University of Geneva CERN The True State-of-the-Art A 2010 paper from the ALPHA experiment titled “The Higgs boson in our lives”, at CERN’s Antiproton Decelerator, during which she described the Higgs • New in-house manufacturing which describes the successful trapping boson discovery and how research into of 38 antihydrogen atoms, is one of fundamental particles has implications • Lower noise 40 landmark papers selected by the US beyond the laboratory. The lecture was • Lower leakage current Department of Energy (DOE) to celebrate part of a rich programme of outreach • Better charge collection its 40th anniversary. The discovery of the events associated with the 2017 European Higgs boson by the LHC’s ATLAS and Conference on Applied Superconductivity Compatible with EPICS tools & libraries CMS experiments was also selected. Other (EUCAS) held in Geneva from 17 to particle-physics results listed include: 21 September and co-organised by CERN 25 mm2 FAST SDD® 55Fe Spectrum Fermilab’s discoveries of the top and in collaboration with the University of 25 mm2 FAST SDD® bottom quarks; the measurement of sin2β Geneva and EPFL-SPC (CERN Courier 800,000 230K, Tpk = 8 µs 1,000,000 with B0 mesons at SLAC; the observation September 2017 p17). Peak to 1 keV background Mn Kα 26,000:1 100,000 at Brookhaven Lab that free quarks and Mn Kβ 600,000 gluons make a perfect liquid; and the Untrapped antihydrogen atoms 10,000 discovery of neutrino oscillations at SNO annihilating on the inner surface of the M e e t i n g s COUNTS 400,000 122 eV FWHM 1,000 and elsewhere. ALPHA trap.

100 CERN School of Computing marks 40th edition E v E n t 200,000 10 First users at European XFEL The CERN School of Computing (CSC) biotechnology lab. At the end of the school, 0 1 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 Energy (keV) aims to promote advanced learning and 59 students passed the optional exam – 14 of knowledge exchange in scientific computing them with distinctions. L Berg/DESY Resolution vs Peaking Time Pace/CERNA 180 Inaugurated on 1 September, the world’s among young scientists and engineers Since 2002, the school has offered a CSC 25 mm2 most powerful X-ray laser – the European involved in particle physics or other sciences. diploma upon successful completion of 170 XFEL in Hamburg, Germany – has now The CSC, along with the CERN Schools of an optional exam. In addition, since 2008,

1606 Standard SDD welcomed its first users. The culmination Physics and the CERN Accelerator School, the university hosting the CSC audits its of a worldwide effort, the facility will are the three schools that CERN has set up to academic programme and incorporates the ® 1505 FAST SDD eventually fire up to 27,000 pulses of intense help train the next generation of researchers CSC into its official teaching programme. X-rays per second to image electronic, across the laboratory’s main scientific and As a result, a formal certificate of five or six 140 chemical and biological processes in technical domains. ECTS (European Credit Transfer System) on eV HM 59 eV 59 HM oneV ti 130 unprecedented detail. The first batch of Since the first CSC in Italy in 1970, the credit points are awarded by the hosting Resolution (eV FWHM @ 5.9 keV) Resolu users aimed to get a better understanding school has visited 21 countries and been university and recognised across Europe for 120 0 1 2 3 4 5 5 of the shape and function of biomolecules, attended by more than 2600 students any doctoral and masters programme. Since Peaking Time (μs) eaing Time µs using techniques such as femtosecond from five continents and 80 nationalities. 2005, CSC management has also organised crystallography. In this first round of Participants are young, come from many Since 1970, the CERN School of Computing an “inverted” CSC (iCSC) and, since 2013, Options: beamtime a total of 14 groups with up to 80 DESY’s Anton Barty (left) and Henry different backgrounds and all have a passion has trained more than 2600 participants a “thematic” CSC (tCSC). The idea behind • 25 mm2 active area collimated to 17 mm2 users each will conduct experiments until Chapman (right) were involved in the first for computing and science. They work from 80 nationalities in scientific computing. the inverted school is to invite CSC alumni to 2 2 March 2018. user experiments. together for two weeks, not only to widen become teachers themselves at a short school • 70 mm collimated to 50 mm their skills but also to establish lifelong links 26 nationalities, students were selected from organised at CERN in the winter. The tCSC, • Windows: Be (0.5 mil) 12.5 µm, or A n n i v E r s A r y that will be useful throughout their careers. a record number of 110 applicants. This year, on the other hand, is a one-week school that C Series (Si3N4) Sibling celebrations at the LHC The 2017 CSC, which took place in Madrid the usual intensive academic programme goes into more depth about a particular topic – • TO-8 package fits all Amptek configurations from 27 August to 9 September, marked its (52 hours of lectures and exercises covering this year’s was efficient parallel processing of 40th edition. Organised together with the base technologies, physics computing and future scientific data. • Vacuum applications CERN In early October, the ATLAS and CMS Universidad Politécnica de Madrid (UPM), data technologies) was complemented Applications for CSC and tCSC 2018 collaborations celebrated their 25th it welcomed 63 students from 37 different by a rich social programme that included will be open early next year. For more birthdays. On 1 October 1992, the nascent universities and institutes. Representing scientific visits to UPM’s wind tunnel and information, visit csc.web.cern.ch/. collaborations each submitted a letter of intent for the construction of a detector to be installed at the proposed LHC, containing Strong discussions in Montpellier detailed specifications that were close to what exist in the final designs. The letters of intent The 20th High-Energy Physics from the formal field-theory approach to – ATLAS, CMS and ALICE at the LHC, for ALICE and LHCb, the LHC’s two other International Conference in Quantum confinement to its phenomenological facets, HERA and COMPASS – during which 40 Years of large experiments, followed a few months Chromodynamics (QCD 17) took place in in addition to searches for physics beyond improved measurements of the QCD coupling Products for Your Imagination later. Earlier in 1992, some 600 physicists and Montpellier, France, on 3–7 July, involving the Standard Model. constant, studies of fragmentation and parton engineers from 250 institutes worldwide had around 50 participants with a large number This year’s event was divided into four main distribution functions were presented. In the ® AMPTEK Inc. met in Évian-les-Bains to discuss the physics of young experimental and theoretical sessions. The first concerned the production second session, the BESIII group presented

[email protected] and detectors of the LHC. Construction of the physicists present. The conference is unique of jets, photons, dibosons, top quarks and experimental results for heavy molecules s www.amptek.com LHC was approved in December 1994. A joint ATLAS and CMS cake. in its coverage of all aspects of QCD, B and D mesons from various experiments and four-quark states, in addition to

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were complemented by theoretical talks on S Bennett/CERN right) and (middle & N Aitor; R Bergerie-Pagadoy (left) credits: Image QCD spectral sum rules, potential models, Deepak Dhital, ambassador of Nepal to the holographic QCD and glueball searches. United Nations office in Geneva, came to CERN The third session was dedicated to the on 19 September, during which he signed an more formal non-perturbative aspects International Co-operation Agreement between of QCD, such as confinement, finite the government of Nepal and CERN concerning temperature and hydrodynamics, while scientific and technical co-operation in the fourth session concerned low-energy high-energy physics and related areas. precision tests of the electroweak Standard Model. The latter included recent measurements of lepton anomalous magnetic moments, where consistent results on the measurements of the cross-sections for e+e– → hadrons were presented by BABAR, BESSIII and CMD-3 and compared to different theoretical contributions (there Participants at the 20th edition of the QCD conference, held in Montpellier in July. is now good agreement among different experiments confirming a 3.6σ discrepancy CMS. Theoretical talks on current LHCb series is an opportunity for participants to with respect to theoretical predictions). anomalies and on the discreteness origin interact in a relaxed atmosphere. Teruo Kishi, science and technology adviser to - The conference ended with different of particle masses were presented, and the New results presented in this conference the minister for foreign affairs, Japan, came to Maris Kucˇinskis, prime minister of the Republic precision measurements of the W, Z and future performance of the ATLAS and CMS also have the advantage of appearing CERN on 14 September. During his trip, Kishi, of Latvia (furthest left), came to CERN on Higgs boson masses and couplings, and with detectors was discussed. just before the larger EPS and ICHEP who is professor emeritus at the University 20 September. Owing to a short machine stop, experimental searches for physics beyond With almost equal numbers of theorists international conferences. QCD18 is of Tokyo, visited the ATLAS visitor centre and he was able to take a quick look at the LHC the Standard Model by LHCb, ATLAS and and experimentalists present, the conference expected to take place from 2 to 6 July 2018. signed the guestbook with CERN director for tunnel and CMS underground area. He also international relations Charlotte Warakaulle and visited the Microcosm, S’Cool LAB and the CERN were so favoured by the students that the Director-General Fabiola Gianotti. computer centre. Baikal school lecturer received an unexpected appreciation prize at the closing ceremony. stays vibrant The astroparticle aspect of the Bailkal school was equally intense, with introductions to dark matter and its various Cold waters and hot scientific discussions candidate particles. IceCube’s results on were the main ingredients of the 17th high-energy astrophysical neutrinos were A Poluektov, University of Warwick international Baikal Summer School on presented, as was the status of high-energy high-energy physics and astrophysics, which cosmic-ray programmes by the Auger and was held from 13 to 20 July in the small TAIGA collaborations. TAIGA, located Russian village of Bolshie Koty on the shore in the Tunka valley near Lake Baikal, of Lake Baikal. More than 50 undergraduate and the Baikal-GVD neutrino detector and PhD students from Russia, Germany, working inside the lake are the two flagship Poland, Italy, India and Romania gathered astroparticle experiments in Russia, and at this remote and scenic location for a full many students working in or planning to week of Siberian-style scientific immersion, join these collaborations participated in the with an intense lecture programme set in school. The astroparticle lecture programme magnificent wilderness. closed with lectures on LIGOʼs recent Technology Metals | Advanced Ceramics The Baikal Summer School is organised discovery of gravitational waves. annually by the Joint Institute for Nuclear In addition to lectures, the students Research (JINR), Dubna, and Irkutsk State presented their own work and participated in High Performance Solution University (ISU). Emerging in the early regular discussion sessions in small groups. for Particle Accelerator 2000s as a summer event for local physics The school offered ample opportunities students, it evolved into a dynamic, fully Summer-school students enjoying the view for students to talk to lecturers outside of H.C. Starck’s global supply chain o ers semi-finished, finished and fully international scientific school, and one of over Lake Baikal. normal office hours, and staff from Irkutsk machined products for high energy physics projects: the major annual particle-physics events in Planetarium organised stargazing sessions > Beam Collimators > Targets > Shutters

Siberia. This year, in addition to funding Model, the basics of QCD and B physics, under the spectacular Siberian skies. > Radiation Shielding > Beam Blockers from JINR and ISU, the school received statistical methods and other topics. A Preparations for the 2018 school, which From pure and alloyed refractory metals: substantial financial support from the selection of results by the ATLAS, CMS will be organised jointly with the European > Molybdenum > Tungsten > Niobium > Tantalum Russian Foundation for Basic Research and and LHCb collaborations were also given, network of doctorate schools in astroparticle Fabrications are available in a wide range of at and round products: Russian energy firm En+ group, while the covering Higgs physics, top-quark properties, physics (ISAPP), are already proceeding > Plate, Sheet, Foil > Bar and Tube Traiektoria foundation provided books for supersymmetry and exotics searches, heavy at full speed. The ISAPP-Baikal Summer Superconducting wire bundles are manufactured from niobium and student prizes. hadron spectroscopy and B-meson decays. school 2018 will strengthen ties between tantalum bar and foils with toll extrusion services for the large diameter The lecture programme maintains a good Students also enjoyed overviews of the vast Europe, JINR and the astroparticle bundles. balance between theory, experiment and field of experimental neutrino physics and experiments conducted at Baikal. [email protected] astroparticle topics, covering the Standard neutrino-mass model building. The latter ● astronu.jinr.ru/school/current. www.hcstarck.com

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O b i t u a r i e s including their most famous one, on the of pioneering contributions to the study angel for a large group of theoretical wounded nucleon model, completed in 1976. of quark–gluon plasma, which was a mere physicists at Jagiellonian University. Throughout his career Wiesław hypothesis at the time. Wiesław was a member of the Polish Dmitry Bardin 1945–2017 developed close relations with the In addition to being a great scientist, Academy of Sciences and of the Polish community of theoretical physicists in Wiesław was also an outstanding lecturer Academy of Arts and Sciences. He was the US, visiting different institutions in and teacher. He was involved in the awarded the highest Polish distinctions, Our colleague Dmitry (Dima) Yurievich Dima Bardin developed ZFITTER and many the late 1960s and early 1970s. He spent organisation of the Cracow School of including the Commander Cross of the Order Bardin, an academic at Dzhelepov other software projects. six months at Stanford University, the Theoretical Physics since its inception in of Polonia Restituta. Laboratory of Nuclear Problems of the National Bureau of Standards, Stony Brook 1961. Together with Andrzej Białas and their His death is a great loss to his friends, Joint Institute for Nuclear Research (JINR), KalinovskayaA Further software packages in which University and the University of Virginia wives, Maria Czyż and Elżbieta Białas, he colleagues and students, both in Cracow Dubna, Russia, left us on 30 June. Dima was directly involved are: muela in Charlottesville, and one year at the helped create a unique institution, which and around the world. We will all miss Dima graduated with honours from for polarised mu-e scattering, GENTLE University of Illinois, Urbana-Champaign. has attracted young scientists and senior this extraordinary scientist and human Moscow State University and started for LEP2 data analysis and HECTOR He also visited for shorter periods the lecturers for 57 years. being, who shared with us the fruits of research work at JINR in 1968. He defended for radiative corrections to ep scattering. University of Washington in Seattle, CERN, From 1972 to 1994, Wiesław was his talent with exceptional modesty – his his PhD thesis under the guidance of Samoil Since 2000 Dima also led the software Utrecht and Munich, and the University editor-in-chief of the leading Polish physics most characteristic virtue. We will miss Bilenky in 1974 based on studies of elastic system SANC for calculations of radiative of Tel Aviv many times. In 1988, Wiesław journal Acta Physica Polonica B, with Maria his inimitable sense of humour and simple pion–electron scattering and rare decays corrections for LHC processes, and together returned to Jagiellonian University and Czyż acting as the managing editor. It is kindness, so much needed in today’s world. of pions and kaons. Since then, Dimaʼs with Giampiero Passarino he authored the produced a stream of work on high-energy impossible to talk about Wiesław without ● Michał Praszałowicz, Jagiellonian scientific work was devoted to the calculation significant monographThe Standard Model scattering of nuclei, resulting in a number mentioning Maria, who was a true guardian University. of complete electroweak and QCD radiative in the Making. corrections in the Standard Model. He had Dima Bardin exemplified faithful and close interactions with many experimental selfless service to fundamental science. collaborations at LEP, SPS, the LHC It is impossible to overestimate his role in Alper Garren 1925–2017 (CERN) and HERA (DESY). contributed substantially to the now-famous creating an atmosphere of high standards in From 1978 to 1986 Dima derived, workshop Z Physics at LEP1, and in 1995 scientific research. With broad knowledge, with various collaborators, electroweak he was a convener of the working group extensive experience and diligence, he was Alper Abdy Garren was born on 30 April machines: the Bevatron, Magnetic Mirror corrections to deep inelastic scattering for event generators for Standard Model a true professional in his field. A severe, 1925 in Oakland, California, and died Fusion Reactors, 88-inch Cyclotron, and developed a pioneering approach processes at LEP2. During 1994–1995 he was debilitating and prolonged illness brought a peacefully on 25 June in the same place. Advanced Light Source (ALS), Fermilab Berkeley Lab to renormalisation in the unitary gauge. a co-ordinator of the precision calculations great deal of suffering and pain, but despite Al attended the US Naval Reserve Proton Synchrotron, the Large Proton–Proton These two projects were the basis of many working group at CERN. The CERN report this he continued working until his last day. Midshipmenʼs School at the University Storage Rings LSR (CERN), ISABELLE now-classical applications of radiative Precision Calculations for the Z Resonance Dima was not only an outstanding scientist of Notre Dame in 1945 and served as a (BNL), and the High Energy Heavy Ion corrections in the Standard Model, performed was the basis for the well-known “blue-band but also a reliable friend and colleague, and a commissioned lieutenant in the US Naval Facility SUMATRAN (Japan). in close co-operation with experiments at plot” of the LEP electroweak working group. wonderful family man. We feel a great loss, Reserve through 1947. By 1950 he had Al was a sweet, kind, generous man CERN and other research centres. ZFITTER was one of the main codes used not only personally but also as a scientific received undergraduate and masters degrees who made friends easily and kept them for With the advent of LEP, Dimaʼs scientific for LEP1 and LEP2 data analyses, and was community. from the University of California, Berkeley, life. He loved to travel and was especially activity focused on precise calculation of the a central theoretical tool for predicting the ● Andrej Arbuzov, Wolfgang Hollik, Lida and in 1955 he completed his PhD at the drawn to the culture and people of Asia. properties of the Z boson, in particular by masses of the top quark and the Higgs boson Kalinovskaya and Tord Riemann, on behalf Carnegie Institute of Technology. He loved the performing arts and was developing the ZFITTER project. In 1989 he prior to their discoveries. of his colleagues and friends. A career particle physicist at Berkeley Lab, a patron of the San Francisco Opera, located on the hill above the UC Berkeley the San Francisco Symphony and the campus, Al wrote his first paper for what Philharmonia Baroque Orchestra. He was · was then the Radiation Laboratory in 1949. a dedicated philanthropist, supporting Wiesław Czyz 1927–2017 He wrote his final paper in 1991 at what had some 200 environmental, human-rights and become the Lawrence Berkeley National performing-arts organisations in his later Laboratory (LBL). years. Outstanding theoretical physicist and former Wiesław Czyż made pioneering contributions Al was a brilliant scientist who designed Alper Garren designed the lattice for the SSC. Physicist, teacher, mentor, world traveller,

editor-in-chief of the journal Acta Physica Kobos A to high-energy nuclear physics. the accelerator lattice for the Superconducting sailor, philanthropist and above all a dear Polonica B, Wiesław Czyż passed away on Super Collider (SSC), in particular inventing SLAC’s PEP-II accelerator and SYNCH friend, Al enriched many lives during his 8 April after a long illness. Wiesław was born During his long research career, Wiesław the “diamond bypass” to allow two beams to – a computational tool used extensively at 92 years. on 2 May 1927 in Lublin, eastern Poland. was associated with many institutions. He be injected and aborted from just one straight particle-physics labs around the world and ● Based on text published in the San His education was interrupted by the Second spent two years (1957–1959) at the Niels section. His career also included work on for which he held a patent. He contributed to Francisco Chronicle by Jon Eisenberg and World War, during which he was active in Bohr Institute in Copenhagen, where the Tevatron, the asymmetric B-Factory at the design and orbit theory of the following Marilee Bailey. the Polish resistance (the Home Army). After he developed an interest in theoretical the war, he completed his master’s degree in high-energy physics, his lifelong scientific mathematics at the Maria Curie-Skłodowska passion. Then, in the early 1960s, he visited University in Lublin. the Stanford Linear Accelerator Centre Maryam Mirzakhani 1977–2017 His career in physics began in 1948, when for one year, where he made significant he moved to Cracow to work at Jagiellonian contributions to our understanding of University. He received his PhD in 1955 for nuclear structure and composite-particle Maryam Mirzakhani, mathematics professor Maryam participated in two International the supervision of Fields Medalist Curtis a dissertation on spin interactions in nuclear scattering. at Stanford University and Fields Medalist Mathematics Olympiads, winning gold McMullen. Before joining Stanford in 2008 matter. Soon after the establishment of the In Poland, he kept in touch with the group in 2014, passed away on 14 July aged just 40. medals both times – once with a perfect she was a fellow of the Clay Mathematics Institute of Nuclear Physics in Cracow, he of theoretical physicists at the Jagiellonian She was the first woman and first Iranian score. After undergraduate studies at Sharif Institute in Cambridge (MA) and a professor

created its theory department, which he University, especially with Andrzej Białas, citizen to win a Fields Medal. University, she moved to the US to enroll in at Princeton University. s headed for 34 years. with whom he published many papers, Born in Teheran, at high-school age a PhD course at Harvard University, under Since her early career as a

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CCNov17_Faces&Places.indd 42 04/10/2017 16:08 CCNov17_Faces&Places.indd 43 04/10/2017 16:08 CERNCOURIER www. V o l u m e 5 7 N u m b e r 9 N o v e mber 2 0 1 7 CERN Courier November 2017 CERN Courier November 2017 Faces & Places Recruitment mathematician, Maryam obtained Mirzakhani, who fundamental results on moduli spaces of was the first F o r advertising e n q u i r i e s , c o n ta c t CERN C o u R i E R recruitment / c l a s s i F i e d, ioP P u b l i s h i n g , te m P l e c i r c u s , te m P l e Way, b r i s t o l bs1 6hg, uK. te l +44 (0)117 930 1264 Fa x +44 (0)117 930 1178 e- m a i l s a l e s @ cerncourier . c o m Riemann surfaces and inhomogeneous woman to be P l e a s e c o n ta c t u s F o r inFormation a b o u t r at e s , c o l o u r o P t i o n s , Publication d at e s a n d d e a d l i n e s . space dynamics – topics at the intersections awarded a Fields between mathematics and physics. One of Medal, worked at her first major results was a counting theorem Stanford Service News the intersection on closed geodesics that unexpectedly led to between Faculty Position in Experimental a new proof of Witten’s conjecture, related mathematics and to the partition function of two-dimensional physics. High-Energy Physics quantum gravity. As Harvard string theorist Cumrun at the Ecole polytechnique fédérale de Lausanne (EPFL) Vafa recalled in his speech at a memorial event held in August, results of Maryam’s work and the techniques she applied in her The School of Basic Sciences of the Ecole Polytechnique Applications should include a motivation letter, a proofs might be applied to solve problems in Fédérale de Lausanne (EPFL) seeks to appoint a tenure- curriculum vitae with a list of research outputs, a string theory. Riemann surfaces are natural as well as supersymmetric field theories, Tao (Fields Medalist, UCLA) wrote in a track assistant professor of experimental high-energy statement of research (max. 3 pages) and teaching ingredients in string theory, where they which are constructed through geometric note about Maryam Mirzakhani, it also physics in the Institute of Physics. interests (max. 1 page), as well as the names and appear both as 2D world-sheets of strings engineering of branes wrapping Riemann promotes the recipient to a role model. In addresses (including e-mail) of at least three references. dynamically evolving in space–time, as surfaces. Maryam’s approach to moduli the case of Maryam Mirzakhani this was The Laboratory for High-Energy Physics is strongly well as 2D internal manifolds on which the spaces provided powerful tools that, in the definitely true: as a female mathematician involved in the LHCb experiment at CERN’s Large Application files should be submitted in PDF format and theory is compactified to reduce its original future, could lead to major advances in and the first woman to win a Fields Medal, Hadron Collider from the time of its conception, and is uploaded by December 15th, 2017 to 10 or 11 dimensions to a more familiar theoretical physics. she will remain a reference figure for future currently making a major contribution to the detector https://facultyrecruiting.epfl.ch/position/6848513 4D scenario. The premature departure of Maryam generations of female scientists. upgrade, with a view to enhance data-taking capability Both applications of Riemann surfaces Mirzakhani represents a huge loss for In addition to an extraordinary scientific to extend the science reach from 2021 onwards. The are of great interest to theoretical physicists. the scientific community, not just for her career, particularly noticeable were her Ongoing research in CERN’s theory scientific excellence. Winning a Fields generosity and humble personality. position offers the opportunity to capitalize on this department directly investigates string Medal not only highlights the academic ● Alessandra Gnecchi and colleagues from investment while also developing ideas for the longer- Enquiries may be addressed to: world-sheet and scattering amplitudes, achievement of the recipient but, as Terrence the CERN theory department. term future, in an environment providing strong technical Prof. Harald Brune support in detector development. Chairman of the Search Committee A PhD degree in particle physics as well as a strong and E-mail: [email protected] growing track record in research and scientific leadership are required. The appointed professor is expected to Superconducting and High For additional information, please consult www.epfl.ch, initiate a creative experimental program, and engage in sb.epfl.ch, iphys.epfl.ch Temperature Metals physics teaching at undergraduate and graduate levels. Significant start-up resources, research budget and state- Elite Material Solutions Limited have become synonymous throughout Europe with of-the-art research infrastructure are available. Salaries EPFL is committed to increasing the diversity of its faculty, and strongly the supply of Tantalum, Niobium RRR, Tungsten and Molybdenum in ALL forms, and benefits are internationally competitive. encourages women to apply. supporting its customers in all aspects achieving their engineering and sourcing goals. Elite Material Solutions Limited has been the company to approach for over 17 years when scientist, research projects managers and industrial design engineers need to investigate, discuss and source superconducting, high temperature and corrosion resistance metals. 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Postdoctoral Research Positions Institute of Physics ASCR, v. v. i., Na Slovance 2, 182 21 Praha 8 LIGO Laboratory [email protected] www.eli-beams.eu

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has as its Applications for postdoctoral research positions with goal the development of gravitational wave physics and astronomy. The LIGO LIGO Laboratory should indicate which of the LIGO The ELI (Extreme Light Infrastructure) Project is an integral part of the Requirements: Laboratory is managed by Caltech and MIT, and is funded by the National sites (Caltech, MIT, Hanford, or Livingston), if any, are European plan to build the next generation of large research facilities. l University degree in optical engineering or experimental physics Science Foundation. It operates observatory sites equipped with laser preferred by the applicant, and which (if any) are likely ELI-Beamlines is a cutting-edge laser facility that is currently being interferometric detectors at Hanford, Washington and Livingston, Louisiana, l Experience in high power laser laboratories to be unworkable. Applications should be sent to constructed in Dolní Břežany (on the southern border of Prague); its which recently made the first confirmed detection of gravitational waves. l HR@ligo.caltech.edu (Electronic Portable Document commissioning is scheduled for end of 2017. ELI will be delivering Engineering skills concerning alignment of optics and targets, as well as A vigorous LIGO Laboratory R&D program supports the development of Format (PDF) submittals are preferred). Caltech and MIT ultra-short, ultra-intense laser pulses lasting typically a few tens of vacuum and electrical installations. enhancements to the LIGO detector as well as astrophysical data analysis, and are Affirmative Action/Equal Opportunity employers. femtoseconds (up to 150 fs) with peak power projected to reach 10 PW. l Knowledge in the use of codes for optical simulations is a plus. development of future detectors and detector technologies. Women, minorities, veterans, and disabled persons are It will make available time synchronized laser beams over a wide range of l Fluent in English for speaking and writing; knowledge of Czech is a plus encouraged to apply. intensities for multi-disciplinary applications in physics, medicine, biology, The LIGO Laboratory anticipates having one or possibly more postdoctoral material science etc. The high laser electric field intensities of the laser l Ability to work in a team as well as independently research positions at one or more of the LIGO sites – Caltech, MIT and at the Applications should include curriculum vitae, list of pulse will be also used for generating secondary sources of e- and p+ and two LIGO Observatories in Hanford, WA and Livingston, LA – beginning in Job conditions: publications (with refereed articles noted), and the high-energy photons. Fall 2018. Hires will be made based on the availability of funding. Successful l The opportunity to participate in this unique scientific project names, addresses, email addresses and telephone The research group RP3 is expanding and recruiting physicists in relevant applicants will be involved in the operation of LIGO itself, analysis of LIGO l numbers of three or more references. Please attach a fields for the design/development of the facility and for preparation of Career growth, professional education data, both for diagnostic purposes and astrophysics searches, and/or the R&D cover letter describing past experience and current and future experimental activities. l program for future detector improvements. We seek candidates across a broad 5 weeks of holiday and other employee benefits future research interests. Applicants should request range of disciplines. Expertise related to astrophysics, modeling, data analysis, In our team we therefore have the following position available: l that three or more letters of recommendations be sent Pleasant work environment electronics, laser and quantum optics, vibration isolation and control systems directly to [email protected] (Electronic Portable Junior/Senior Engineer/Experimental Physicist Applications, containing CV, cover letter, contacts of references, and any other is desirable. Most importantly, candidates should be broadly trained scientists, Document Format (PDF) submittals are preferred). material the candidate considers relevant, should be sent to willing to learn new experimental and analytical techniques, and ready to share (ELI-RP3 ELIMAIA) Consideration of applications will begin December 15, Mrs. Jana Ženíšková ([email protected], +420 601 560 322). in the excitement of building, operating and observing with a gravitational-wave The candidate is supposed to work predominantly on the following topics: 2017 and will continue until all positions have been Please include the following text in your cover letter, to allow us to process observatory. Appointments at the post-doctoral level will initially be for one-year l filled. Implementation of various optical devices (mirrors, focusing optics, your personal details: with the possibility of renewal for up to two subsequent years. cameras, microscope objectives, and laser diagnostics) in vacuum chambers I agree that, according to the decree 101/2000 coll. (Czech Republic), my personal where initial commissioning RP3 experiments (particle acceleration by details sent to FZU AVCR, v.v.i, Na Slovance 2, 18221 Praha 8, Czech Republic can lasers) will be carried out with 100-TW class lasers (and later PW-class). be used for the purpose of obtaining employment and management of database of Caltech and MIT are Affirmative Action/Equal Opportunity Employers l Operation of laser alignment and diagnostic systems, including data employment candidates. This permission is given for the period of one year and can Women, Minorities, Veterans, and Disabled Persons are encouraged to apply acquisition and transfer to local control systems be at any time withdrawn by giving a notice in writing. More information about LIGO available at www.ligo.caltech.edu

The Department of Physics and Astronomy at Texas Tech possess an outstanding research record, and show promise of University, as part of its strategic growth plan, invites excellent teaching at both undergraduate and graduate levels. applications for a tenure-track position in experimental particle Candidate is expected to garner extramural funding to support his/ physics at the assistant professor level; exceptional candidates at her research. Service to the department, college, and university is Working in a place like a more senior level may be considered. also expected.

The starting date is September 2018. The members of the Applicants should submit a vita, list of publications, statement nowhere else on earth…. experimental particle physics group at Texas Tech (Akchurin, of research interests and plans, teaching philosophy, and contact Kunori, Lee, Volobouev, and Wigmans) actively participate in the information for at least three references. Applications should be CMS experiment at CERN and maintain a rigorous R&D program submitted online jobs.texastech.edu using requisition ID 11830. in advanced detector physics. In addition to the ongoing beyond Inquiries should be sent to Professor Nural Akchurin (nural. The place for your next career step? Standard Model searches, we share significant responsibilities for [email protected]). Applications will be reviewed starting the upgrade of the CMS calorimeters for the high luminosity LHC. December 1st 2017 and will continue until the position is filled. The group enjoys strong infrastructure support: the Advanced People at CERN are driven by a shared goal, a single purpose. They want to achieve the impossible, to Particle Detector Laboratory is well-suited for R&D and production As an Equal Employment Opportunity/Affirmative Action of detectors based on scintillator and silicon systems, and the High employer, Texas Tech University is dedicated to the goal of building do what’s never been done before. Everyone here strives to be the best they can be, true specialists and Performance Computing Center allocates substantial resources in a culturally diverse faculty committed to teaching and working in support of the group’s analysis work. The university has recently a multicultural environment. We actively encourage applications needed to make the experiments succeed are as world-class as the science behind them. been ranked in the Highest Research Activity category by the from all those who can contribute, through their research, teaching, Carnegie Foundation. and/or service, to the diversity and excellence of the academic community at Texas Tech University. The university does not If you’re looking for a new challenge in engineering & tech- We expect the new experimental faculty member to strengthen and discriminate on the basis of an applicant’s race, ethnicity, color, complement the ongoing research in CMS, particularly in detector religion, sex, sexual orientation, gender identity, national origin, upgrade effort, or to initiate a new and significant research program age, disability, genetic information or status as a protected veteran. : in any area of experimental particle physics. Candidate must have a Texas Tech welcomes consideration of dual career and professional cern.ch/jobs. Take part! Ph.D. in physics and at least two years of post-doctoral experience, couple accommodations.

CERNCOURIER www. V o l u m e 5 7 N u m b e r 9 N o v e mber 2 0 1 7 CERN Courier November 2017 CERN Courier November 2017 Bookshelf Bookshelf the topic. Chapters 5 and 6 are specific to Kinematic theory (KT) was born in the discuss the properties of many-body nuclei, C o m p i l e d b y V i r g i n i a g r e C o, Cern the ITER design because they describe the 19th century and aims to derive the properties and also extend the treatment of lepton ELM instabilities in the ITER tokamak of macroscopic matter from the properties scattering to include the weak interactions Radioactivity and Radiation: What They and the solutions adopted for their control. of its constituent microscopic particles. The of leptons with nucleons and nuclei. Are, What They Do, and How to Harness Concluding the part dedicated to the formulation of KT within special relativity The last group of chapters is dedicated Them fusion-reactor transient phase, steady-state was completed in the 1960s. to relativistic heavy-ion physics and By Claus Grupen and Mark Rodgers operations and plasma diagnostics Relativistic KT has traditional nuclear and particle astrophysics. A brief Springer International Publishing techniques are described in chapters 7 and 8, applications in astrophysics and cosmology, perspective on physics beyond the Standard Have you ever thought that batteries respectively. two fields that tend to rely on observations Model is also provided. capable of providing energy over very long The tokamak’s complex magnetic field is rather than experiments. But it is now The volume includes approximately periods could be made with radioisotopes? able to confine charged particles in the fusion becoming more accessible to direct tests due 120 exercises and is completed by two Did you know that the bacterium plasma but not neutral particles. Neutron to recent progress in ultra-intense lasers and appendices collecting values of important deinococcus radiodurans can survive bombardment of surfaces can be viewed inertial fusion, generating growing interest constants, useful equations and a brief enormous radiation doses and, thanks as an inconvenience, making it necessary in KT in recent years. summary of quantum theory. to its ability to chemically alter highly to ensure the walls are radiation hard, or The book has three parts. The first radioactive waste, it could be potentially an advantage, turning the surfaces into a deals with the fundamental equations The Grant Writer’s Handbook: How to Write employed to clean up radioactively breeding blanket to generate further tritium and methods of the theory, starting with a Research Proposal and Succeed contaminated areas? And do you believe fuel. Radiation hardness of the tokamak walls the evolution of the basic concept of KT By Gerard M Crawley and Eoin O’Sullivan that cockroaches have an extremely high is discussed in chapter 9, while chapter 10 from nonrelativistic to special and general Imperial College Press radiation tolerance? Apparently, the latter explains how ITER will transmute a lithium relativistic frameworks. The second part This book is designed as a is a myth. These are a few of the curiosities blanket into tritium via bombardment with gives an introduction to computational “how to” guide to writing grant contained in this “all that you always fusion neutrons. The IFMIF (International physics and describes the main numerical proposals for competitive peer wanted to know about radioactivity” Fusion Materials Irradiation Facility) methods used in relativistic KT. In the third review. Nowadays researchers book from Grupen and Rodgers. It gives project, conceived for fusion-material tests part, a range of applications of relativistic KT are often required to apply to a comprehensive overview of the world of and still in its final design phase, is also are presented, including wave dispersion and funding agencies to secure radioactivity and radiation, from its history briefly presented. The book closes with thermalisation of relativistic plasma, kinetics a budget for their work, but being a good to its risks for humans. some predictions about the expectations to of self-gravitating systems, cosmological researcher does not necessarily imply being The book begins by laying the be fulfilled by ITER, before proceeding to structure formation, and neutrino emission able to write a successful grant proposal. groundwork with essential, but quite the design of DEMO – a future tokamak for during gravitational collapse. Typically, the additional skills and insights detailed (similar to a school textbook), electrical-energy production. Written by two experts in the field, needed are learnt through experience. information about the structure of matter, most of them drawn by one of the authors. ITER Physics In summary, ITER Physics is a book the book is intended for students who This timely book aims to guide how radiation is generated, how it interacts The book emphasises that radiation is By C Wendell Horton Jr and Sadruddin Benkadda for expert scientists who are looking for a are already familiar with both special researchers through the whole process, from with matter and how it can be measured. In everywhere and that almost everything World Scientific compact overview of the latest advances and general relativity and with quantum conceiving the initial research idea, defining the following chapters, the book explores around us is radioactive to some degree: This 235 page book is dedicated to the in tokamak physics. I appreciated the electrodynamics. a project and drafting a proposal, through the substantial benefits of radioactivity there is natural radioactivity in our ITER tokamak, the deuterium–tritium exhaustive set of references at the end of to the review process and responding to through its many applications (not only homes, in the food that we eat and the fusion reactor under construction in France, each chapter, since it provides a way to Foundations of Nuclear and Particle reviewers’ comments. Drawing on their positive, but also negative and sometimes air that we breathe. Radiation from the which aims to investigate the feasibility of go deeper into concepts not exhaustively Physics own experience as reviewers in a number questionable) and the possible risks natural environment does not present a fusion power. The book provides a concise explained in the book. Plasma-fusion By T W Donnelly, J A Formaggio, B R Holstein, of different countries, the authors provide associated with its use. The authors deal hazard; however, radiation levels higher overview of the state-of-the-art plasma physics is complex, not only because it is a R G Milner and B Surrow many important tips to help researchers mainly with ionising radiation; however, than the naturally occurring background physics involved in nuclear-fusion processes. many-body problem but also because our Cambridge University Press communicate both the quality of their in view of the public debate about other can be harmful to both people and the Definitely not an introductory book – not knowledge in this field is limited, as the This textbook aims to present research and their ability to carry it out and kinds of radiation (such as mobile-phone environment. These artificially increased even for a plasma-physics graduate student authors stress. I would have appreciated the foundations of both nuclear manage a grant. The authors illustrate their and microwave signals), they include a brief radiation levels are mainly due to the – it would be useful as a reference text for more graphic material in some parts: in and particle physics in a single guidelines with the help of many examples chapter on non-ionising radiation. Also nuclear industry and have therefore risen experts. Across 10 chapters, the authors order to fully understand how a fusion volume in a balanced way, and of both successful and unsuccessful grant interesting are the final sections, provided substantially since the beginning of describe the physics learned from previous reactor works, one has to think in 3D, so to highlight the interconnections applications, and emphasise key messages as appendices, which summarise the main the civil-nuclear age in the 1950s. This tokamak projects around the world and the schematics are always helpful. between them. The material is with quotes from reviewers. technologies of radiation detectors as well approach helps readers to put things in application of that experience to ITER. ● Rogelio Palomo, University of Seville, Spain organised from a “bottom-up” point of view, The book also contains valuable advice as the fundamental principles of radiation perspective and allows them to compare After an introduction to the ITER project, moving from the fundamental particles of for primary investigators on how to set up protection. In the latter, the rationale the numbers and specific measurement the conventional magneto-hydrodynamic Books received the Standard Model to hadrons and finally to their research budget, manage people and behind current international rules and quantities that are used in the radiation- description of plasma physics is discussed, few- and many-body nuclei built from these lead their project. Two appendices at the end regulations, put in place to avoid excessive protection arena. These quantities are the with strong emphasis on the geometry Relativistic Kinetic Theory, with hadronic constituents. of the volume provide website addresses and radiation exposure for radiation workers same used by the media, for instance, to of the divertor (located at the bottom of Applications in Astrophysics and The first group of chapters introduces references, as well as an outline of how to and the general public, is clearly explained. address the general public when a radiation the vacuum vessel to extract heat and Cosmology the symmetries of the Standard Model. The organise a grant competition. This extensive topic is covered using incident occurs. reduce contamination of the plasma from By Gregory V Vereshchagin and Alexey G Aksenov structure of the proton, neutron and nuclei Aimed primarily at early career easily understood terms and only Not only will this book enrich the impurities). Chapter 3 deals with the problem Cambridge University Press in terms of fundamental quarks and gluons researchers applying for their first grant, elementary mathematics is employed reader’s knowledge about radioactivity of alpha-particle distribution, which is a This book provides an is then presented. A lot of space is devoted the book will also be beneficial to more to describe the essentials of complex and radiation, it will also provide them source of Alfven and cyclotron instabilities. overview of relativistic kinetic to the processes used experimentally to experienced scientists, to the administrators nuclear-physics phenomena. This makes for with tools to better understand many Edge localised mode (ELM) instabilities theory, from its theoretical unravel the structure of hadrons and to of universities and institutions that support pleasant reading intended for the general of the related scientific issues. Such associated with the divertor’s magnetic foundations to its applications, probe quantum chromodynamics, with their researchers during the submission public interested in radioactivity and comprehension is crucial for anyone who is separatrix are also discussed. Conditions of passing through the various particular focus on lepton scattering. process, and to the staff of recently radiation, but also for science enthusiasts willing to develop their own point of view turbulent transport are assumed throughout, numerical methods used when Following the treatment of two-nucleon established funding organisations, who and inquisitive minds. As a bonus, the book and be active in public debates on the topic. so chapter 4 provides a general review of analytical solutions of complex equations systems and few-body nuclei, which have may have little experience in organising is illustrated with eye-catching cartoons, ● Federico Ravotti, CERN. our (mainly experimental) knowledge of cannot be obtained. mass numbers below five, the authors peer-review competitions.

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A l o o k b A c k t o cERN c o u R i E R v o l . 14, N o v E m b E R 1974, c o m p i l E d b y p E g g i E R i m m E R

B r o o k h a v e n Present and future programmes The Brookhaven National Laboratory Several months ago the foam fire protection [established in 1947] for many years enjoyed system for the 7-foot bubble chamber came on a pre-eminent reputation among high-energy automatically because of an electrical design physics research centres. In its heyday, many fault in the manufacturer’s circuit. The of the major discoveries fell to the 33 GeV incident provided a vivid demonstration of Alternating Gradient Synchrotron, AGS, the system’s ability to flood the entire building which was the highest energy machine in with extinguishing foam very quickly. the world. The inevitable leap-frogging has Clean-up was completed in about a day and since taken place and facilities at Serpukhov, left the bubble chamber whiter than white. CERN and the FermiLab have extended the fields of research beyond the reach of the end of September. The chamber came into give protons onto four targets. An experiment BNL machine. There is therefore the keenest action in 1963, collecting some 12 million fed by target A is by a MIT/Brookhaven team interest in BNL’s project for the future – the photographs for seventy experiments. Its led by S C C Ting, to continue the study of very high-energy collider ISABELLE. particular moment of glory came in 1964, the electromagnetic properties of the nucleon Of course, the major activities remain with the identification of the omega minus by measuring electron pairs emerging from centred on the high energy physics [three strange quarks] in the experiment led proton–proton collisions.* programme and the operation and by N P Samios. The bubble chamber burden *Fascinating news from this experiment development of the AGS. The experimental is now taken up by the 7-foot chamber sitting at the beginning of November: they believe programme has been fed by beams from an in the North Experimental area, where it is they have seen a new particle (baptised the internal target, by two fast ejected beams to fed by a neutrino beam. J particle) of mass 3.1 GeV which decays into the 80-inch and 7-foot bubble chambers, and In the East Experimental Area an internal an electron–positron pair. The electron– by a slow ejected beam to a variety of counter target provides a neutral kaon beam, a positron ring SPEAR at Stanford also has experiments. separated 3 GeV/c negative kaon beam and seen it. Another tantalising contribution to Financial restrictions forced the test beams. The slow ejected beam, via two the hadron/lepton relationship. close down of the 80-inch chamber at the splitting stations and a bending station, can ● Compiled from texts on pp388–391.

D u B n a / o r s a y Collaborative look The Orsay mass spectrometer swings into the air outside the Laboratory of Nuclear at the nucleus Reactions at Dubna. Dubna’s Laboratory of Nuclear Reactions will get together again, perhaps when the under G N Flerov got together this year 4-m cyclotron, now under construction, with the Orsay mass spectroscopy group of comes into action and opens the door to a R Klapisch to bring their combined talents to new range of nuclear studies. bear on the study of the nucleus. ● Compiled from texts on pp391–392. The Laboratory has one of the world’s finest heavy ion machines – a 3-m cyclotron capable of accelerating ions to energies Compiler’s Note of 8 MeV per nucleon with intensities up The fascinating footnote of course concerned the J/ψ meson (charm– ACP to 200 µA. The Orsay group has a high anticharm), named J at BNL, ψ at Stanford. Sam Ting and Burton Richter reputation in nuclear and mass spectroscopy. shared the 1976 Nobel prize for this discovery that sparked the 1974 The team has done notable work at the November Revolution in particle physics and furthered acceptance of the Dry compact multi-stage Roots pumps for particle-free applications CERN proton synchrotron particularly on a Standard Model. Additional evidence had come in 1975 when a charmed series of sodium and lithium isotopes. Their Λ baryon (comprising an up, down and charm quark) was recorded in the ■ spectrometer is a mobile instrument that BNL 7-foot bubble chamber. This clinched arguments for the existence of Clean and dry vacuum could be readily transported to the cyclotron. a second generation of matter. ■ Particle-free, extremely reliable with long-term stability An agreement was reached between Unfortunately, the ISABELLE 200+200 GeV proton collider was dropped ■ Low maintenance Dubna and the Institut National de Physique in 1963, unfinished. However, parts of its tunnel, experimental hall and ■ Nucléaire et de Physique des Particules for Special version fluorine free available magnet infrastructure were salvaged and reused for BNL’s Relativistic 500 hours of beam time. The experiments began in June and were completed at the end Heavy Ion Collider (RHIC), approved in 1991 and operational in 2000. This was the first heavy-ion collider of August. and is still the only spin-polarised proton collider. RHIC produces like-on-like collisions of copper, gold and The collaboration has been fruitful uranium ions, as well as colliding protons, deuterons, helium-3 and copper on gold. for both parties and it is likely that they Are you looking for a perfect vacuum solution? Please contact us: 50 Pfeiffer Vacuum (Schweiz) AG · T +41 44 444 22 55 · F +41 44 444 22 66 [email protected] · www.pfeiffer-vacuum.com

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5 V i ew p o i n t F e a t u r e s 37 F a ce s & P l a ce s 19 The physicist’s guide to the universe 7 N ew s Sometimes referred to as the bible of particle physics, during the last 45 R ec r u i t me n t Xenon beams light path to gamma factory CLEAR prospects for 60 years the Review of Particle Physics has become the number-one • • 48 B oo k s h elf accelerator research • China neutron source sees first beam• UK reference in the field, detailing more than 38,000 measurements. neutrino investment steps up Fastest spinning fluid clocked • 25 Birth of a symmetry 50 A r c h i ve by RHIC LHCb digs deeper into lepton-flavour universality • • Half a century ago, Weinberg published a paper that unified the CMS observes top quarks in proton–nucleus collisions ATLAS • electromagnetic and weak interactions and revolutionised our experiment makes precision measurement of top-quark mass • understanding of the fundamental forces. ALICE studies possible light tetraquark 31 Model physicist 15 S c i e n cew a t c h Steven Weinberg talks to CERN Courier about his seminal 1967 work and discusses where next for particle physics following the discovery 17 A s t r ow a t c h of the Higgs boson.

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