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CERN Courier–Digital Edition
CERNMarch/April 2021 cerncourier.com COURIERReporting on international high-energy physics WELCOME CERN Courier – digital edition Welcome to the digital edition of the March/April 2021 issue of CERN Courier. Hadron colliders have contributed to a golden era of discovery in high-energy physics, hosting experiments that have enabled physicists to unearth the cornerstones of the Standard Model. This success story began 50 years ago with CERN’s Intersecting Storage Rings (featured on the cover of this issue) and culminated in the Large Hadron Collider (p38) – which has spawned thousands of papers in its first 10 years of operations alone (p47). It also bodes well for a potential future circular collider at CERN operating at a centre-of-mass energy of at least 100 TeV, a feasibility study for which is now in full swing. Even hadron colliders have their limits, however. To explore possible new physics at the highest energy scales, physicists are mounting a series of experiments to search for very weakly interacting “slim” particles that arise from extensions in the Standard Model (p25). Also celebrating a golden anniversary this year is the Institute for Nuclear Research in Moscow (p33), while, elsewhere in this issue: quantum sensors HADRON COLLIDERS target gravitational waves (p10); X-rays go behind the scenes of supernova 50 years of discovery 1987A (p12); a high-performance computing collaboration forms to handle the big-physics data onslaught (p22); Steven Weinberg talks about his latest work (p51); and much more. To sign up to the new-issue alert, please visit: http://comms.iop.org/k/iop/cerncourier To subscribe to the magazine, please visit: https://cerncourier.com/p/about-cern-courier EDITOR: MATTHEW CHALMERS, CERN DIGITAL EDITION CREATED BY IOP PUBLISHING ATLAS spots rare Higgs decay Weinberg on effective field theory Hunting for WISPs CCMarApr21_Cover_v1.indd 1 12/02/2021 09:24 CERNCOURIER www. -
Jul/Aug 2013
I NTERNATIONAL J OURNAL OF H IGH -E NERGY P HYSICS CERNCOURIER WELCOME V OLUME 5 3 N UMBER 6 J ULY /A UGUST 2 0 1 3 CERN Courier – digital edition Welcome to the digital edition of the July/August 2013 issue of CERN Courier. This “double issue” provides plenty to read during what is for many people the holiday season. The feature articles illustrate well the breadth of modern IceCube brings particle physics – from the Standard Model, which is still being tested in the analysis of data from Fermilab’s Tevatron, to the tantalizing hints of news from the deep extraterrestrial neutrinos from the IceCube Observatory at the South Pole. A connection of a different kind between space and particle physics emerges in the interview with the astronaut who started his postgraduate life at CERN, while connections between particle physics and everyday life come into focus in the application of particle detectors to the diagnosis of breast cancer. And if this is not enough, take a look at Summer Bookshelf, with its selection of suggestions for more relaxed reading. To sign up to the new issue alert, please visit: http://cerncourier.com/cws/sign-up. To subscribe to the magazine, the e-mail new-issue alert, please visit: http://cerncourier.com/cws/how-to-subscribe. ISOLDE OUTREACH TEVATRON From new magic LHC tourist trail to the rarest of gets off to a LEGACY EDITOR: CHRISTINE SUTTON, CERN elements great start Results continue DIGITAL EDITION CREATED BY JESSE KARJALAINEN/IOP PUBLISHING, UK p6 p43 to excite p17 CERNCOURIER www. -
The Standard Model
The Standard Model by Christine Sutton In May 1983, the central detector of the UA1 experiment at CERN's proton-antiproton collider showed the tell-tale signature of the long-awaited Z particle as it decays into an electron-positron pair (arrowed). As the electrically neutral carrier of the weak force, the Z° plays a vital role in the Standard Model. The initial evidence from Fermilab (see previous article) for the long awaited sixth ('top') quark puts another rivet in the already firm structure of today's Standard Model of physics. Analysis of the Fermilab CDF data gives a top mass of 174 GeV with an error of ten per cent either way. This falls within the mass band predicted by the sum total of world Standard Model data and underlines our understanding of physics in terms of six quarks and six leptons. Model encompasses all the elemen their interactions emerge. Instead it is In this specially commissioned tary particles we now know and three an amalgam of the best theories we overview, physics writer Christine of the fundamental forces. The basic have, which we can bolt together Sutton explains the Standard building blocks are two sets or because they have enough in com Model. "families" or "matter particles" - the mon to suggest an underlying unity, quarks and the leptons (see page 5). although due to our ignorance the These particles interact with each joins still clearly show. t is nearly 100 years since the other through the exchange of force The structure as a whole rests on a I discovery of the first subatomic carriers or "messengers". -
The Challenge of Neutrinos by Christine Sutton
The challenge of neutrinos by Christine Sutton Neutrino pioneers - left to right, Paul Dirac, Wolfgang Pauli., Rudolf Peierls. (Photo MP Niels Bohr Library) Earlier this year, a team of physicists working at Los Alamos claimed a possible sighting of neutrino oscillations (June, page 13). However even before the claim appeared in the scientific literature, newspaper reports had leaked the possible findings and their implications. Detecting particles which can pass unhindered through the Earth provides the ultimate physics challenge. Neutrinos have always captivated public imagination and make compelling reading. In the wake of the latest neutrino episode, Oxford physi cist and science writer Christine Sutton looks back on the short but volatile history of the neutrino and its attendant publicity. strangers to controversy, for they beta-decay electrons varies continu With the availability of high were in a sense born amidst it, and ously up to a maximum, with peaks energy neutrino beams in the as recent work on neutrino oscilla ("lines") at only a few energies. And 1970s, physicists eagerly tions demonstrates they continue to he was able to explain how the scoured each new batch of data fuel debate. This is of course largely photographic technique could "fake" for signs of exciting new physics. to do with the fact that neutrinos have lines through its great sensitivity to But few initial 'sightings' proved no electric charge and experience small changes in intensity. to be of substance. One of the only the weak nuclear force, making The First World War interrupted major problems faced by such them supremely difficult to detect. -
Taking the Subatomic Grand Tour the Secrets of the World of Elementary Particles Revealed
book reviews Taking the subatomic Grand Tour The secrets of the world of elementary particles revealed. The Particle Odyssey: A Journey to the Heart of Matter by Frank Close, Michael Marten & FERMILAB Christine Sutton Oxford University Press: 2002. 246 pp. £29.95, $45. Ken Peach The development of the standard model of particles and their interactions is one of the major scientific achievements of the twen- tieth century. The electron was the first ‘elementary particle’ to be discovered, by J. J. Thomson (working largely on his own) in 1897, and the top quark was the last of the standard model’s ‘fundamental fermions’ to be discovered, by two large teams at the Tevatron near Chicago in 1995. In between, special and general relativity, quantum mechanics and a deep understanding of symmetry (explicit and hidden, global and local, absolute and spontaneously broken) have transformed our understanding of the dynamics of the Universe. Within this frame- work, a remarkably complete description of the way in which the Universe works has Problem particle: the top quark, here decaying into muons (blue tracks), wasn’t discovered until 1995. been developed, and all but one of its ingre- dients experimentally verified — only the ingredient (quarks, leptons, gauge bosons tions. Most of the loopholes have since been elusive Higgs particle remains undetected. and other whimsies associated with high- closed: the top quark has now been discov- The Particle Odyssey describes a century energy physics) is described and illustrated, ered, the electroweak sector has survived of discovery and creativity through a series along with photographs and biographical precision scrutiny at the Large Electron– of stunning images and photographs. -
The Great Survivor
Dubna - the great survivor atoms are now around the corner. This year, as CERN celebrates its chine in the world. This machine is The Conference closed with the 40th anniversary (November, page still operational, and features in the award of N. Hamann Prize to A. 26), not far behind in the celebration Guinness Book of records as the Masoni of Cagliari, for his presenta stakes is the Joint Institute for Nu planet's largest electromagnet. tion on a high statistics study of iota clear Research, Dubna, near Mos While eclipsed by the new genera decay with the Obelix spectrometer. cow, established in 1956. While tion of strong focusing machines, the This Prize, funded by the Jozef CERN's goal was to provide a Synchrophasotron enjoyed a new Stefan Institute, Ljubljana, is in physics platform on which to rebuild lease of life as a heavy ion machine memory of Niklaus Hamann, PS Western European science after (up to silicon-28), as well as provid coordinator and LEAR physicist who World War II, JINR had a similar ing polarized deuteron beams. The died last year, aged 40. mission for the USSR and the social machine currently runs for some ist countries, including Eastern 1,500 hours per year, providing Europe. research material for more than 500 The fact that both organizations are scientists from 100 institutions. reaching their 40th anniversary The next energy step had very testifies to their success. While their different scenarios at CERN and at aims were very similar, their political JINR. In in the early 1970s, CERN contexts and scientific strategies decided to build the '300 GeV have led along very different routes. -
Thirty Years of Erice on the Brane1
IMPERIAL-TP-2018-MJD-03 Thirty years of Erice on the brane1 M. J. Duff Institute for Quantum Science and Engineering and Hagler Institute for Advanced Study, Texas A&M University, College Station, TX, 77840, USA & Theoretical Physics, Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom & Mathematical Institute, Andrew Wiles Building, University of Oxford, Oxford OX2 6GG, United Kingdom Abstract After initially meeting with fierce resistance, branes, p-dimensional extended objects which go beyond particles (p = 0) and strings (p = 1), now occupy centre stage in the- oretical physics as microscopic components of M-theory, as the seeds of the AdS/CFT correspondence, as a branch of particle phenomenology, as the higher-dimensional pro- arXiv:1812.11658v2 [hep-th] 16 Jun 2019 genitors of black holes and, via the brane-world, as entire universes in their own right. Notwithstanding this early opposition, Nino Zichichi invited me to to talk about su- permembranes and eleven dimensions at the 1987 School on Subnuclear Physics and has continued to keep Erice on the brane ever since. Here I provide a distillation of my Erice brane lectures and some personal recollections. 1Based on lectures at the International Schools of Subnuclear Physics 1987-2017 and the International Symposium 60 Years of Subnuclear Physics at Bologna, University of Bologna, November 2018. Contents 1 Introduction 5 1.1 Geneva and Erice: a tale of two cities . 5 1.2 Co-authors . 9 1.3 Nomenclature . 9 2 1987 Not the Standard Superstring Review 10 2.1 Vacuum degeneracy and the multiverse . 11 2.2 Supermembranes . -
Jan/Feb 2015
I NTERNATIONAL J OURNAL OF H IGH -E NERGY P HYSICS CERNCOURIER WELCOME V OLUME 5 5 N UMBER 1 J ANUARY /F EBRUARY 2 0 1 5 CERN Courier – digital edition Welcome to the digital edition of the January/February 2015 issue of CERN Courier. CMS and the The coming year at CERN will see the restart of the LHC for Run 2. As the meticulous preparations for running the machine at a new high energy near their end on all fronts, the LHC experiment collaborations continue LHC Run 1 legacy to glean as much new knowledge as possible from the Run 1 data. Other labs are also working towards a bright future, for example at TRIUMF in Canada, where a new flagship facility for research with rare isotopes is taking shape. To sign up to the new-issue alert, please visit: http://cerncourier.com/cws/sign-up. To subscribe to the magazine, the e-mail new-issue alert, please visit: http://cerncourier.com/cws/how-to-subscribe. TRIUMF TRIBUTE CERN & Canada’s new Emilio Picasso and research facility his enthusiasm SOCIETY EDITOR: CHRISTINE SUTTON, CERN for rare isotopes for physics The thinking behind DIGITAL EDITION CREATED BY JESSE KARJALAINEN/IOP PUBLISHING, UK p26 p19 a new foundation p50 CERNCOURIER www. V OLUME 5 5 N UMBER 1 J AARYN U /F EBRUARY 2 0 1 5 CERN Courier January/February 2015 Contents 4 COMPLETE SOLUTIONS Covering current developments in high-energy Which do you want to engage? 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. -
People and Things
People and things On people Among the awards distributed at the recent joint annual meeting of the American Physical Society and the American Association of Phy sics Teachers were the Dannie Heineman Prize for Mathematical Physics, to John C. Ward of Mac- quarie University, Australia, for his contributions to the development of particle gauge theories, and the Oersted Medal for physics teach ing, to 1.1. Rabi of Columbia Univer sity. LEP people Now that the LEP electron-positron collider project is under way at CERN, decisions have been taken on the management of the machine construction and on preparations for the experimental programme. At CERN itself, a LEP Manage ment Board has been set up to sending institution. We have advised One of the international discussion panels study and propose solutions to at the Pan American Symposium on High and encouraged the first user group Energy Physics and Technology, held at major problems of the construction from Mexico. We are seeking mod Cocoyoc, Mexico, in January. Left to right, programme and to share respon est Foundation and International R. Taylor from SLAC (representing Canada), sibility for major decisions concern Fermilab Director Leon Lederman Agency support in order to minimize (representing the US), J. Flores of Mexico, ing the project. The members of the problems of government involve M. Kreisler of the US, C Avilez of Mexico, the Board (appointed for two ment. Agreements between institu and Burt Richter also from SLAC, years) are E. Picasso (Chairman), representing the US. tions are simple to administer and G. Plass, H. Laporte. -
CERN Courier April 2014 Viewpoint Cividec Instrumentation
CERN Courier April 2014 Viewpoint cividec Instrumentation CIVIDEC Instrumentation is a R&D company born from the cutting-edge technology of CERN. We specialise in turn-key The 1980s: spurring collaboration solutions for beam diagnostics based on CVD diamond technology. Herwig Schopper recalls a transferred to new assignments. Another element of “anti-growth” had decade of growth at CERN. long-term consequences. Council was Diamond Detectors convinced that the scientifi c programme was fi rst class, but had doubts about the effi ciency of management. An evaluation committee The 1980s were characterized was established to assess the human and by two outstanding material resources, with a view to reducing achievements that were to the CERN budget. In the end, the committee infl uence the long-term declined to consider a lower material future of CERN. First came the discovery budget because this would undoubtedly of the W and Z particles, the carriers of the jeopardize the excellent scientifi c record of weak force, produced in proton–antiproton Herwig Schopper in 1982: with LEP a “new CERN. They proposed instead a reduction collisions at the Super Proton Synchrotron ‘sociology’ for international scientifi c of staff from about 3500 to 2500, through (SPS) and detected by the UA1 and UA2 co-operation was born”. (Image credit: an early retirement programme, and during experiments. These were the fi rst, now-typical CERN-PHOTO-8205525.) the construction of the LHC this was even collider experiments, covering the full lowered to 2000. However, to cope with solid angle and requiring large groups the time with Israel and Turkey failed, for the increasing tasks and the rising number of collaborators from many countries. -
UNESCO Coupons
value of the self-diffusion coefficient of SI, needed to arrange the arriving atoms on proper lattice sites. Linear extrapolation of this border line to higher temperatures yields an intersection point with the LCVD curve at about 1520 K. This value Is In good agreement with the temperature limit we find for single-crystal growth of rods. The orientation of the rod axis was found to be close to either <100> or < 110> crystal lographic directions. Conclusion Laser Induced deposition from the gas phase allows single-step production of material patterns with lateral dimensions from 0.5 µm to several mm. Typical deposi tion rates in laser pyrolysis are 10 to 100 Underlining the international character of CERN, both organisational and physical, the µm/s compared to 10 to some 100 A/s In start of construction of LEP — the 130-130 GeV electron-positron storage rings — was laser photolysis. The scanning velocities formally inaugurated by the Presidents of both France and Switzerland on 13 September. possible in laser pyrolysis reach at least up In the photograph taken at the ground-breaking ceremony are to the left of Francois to about 500 µm/s for strongly adherent Mitterand of France, Emilio Picasso, Director of the LEP Project and to the right of Pierre films. Laser pyrolysis at visible wavelengths Aubert of Switzerland, Herwig Schopper, the Director-General of CERN. The 27 km combines high deposition rates and small circumference of LEP will lie 3/4 in France and 1/4 in Switzerland. lateral dimensions of deposits with stan dard laser techniques, simple optics and adjustment. -
STANFORD (SLAC) Asymmetry Parameter Using a Dictate Where This Quark Can Sit If the Polarized Electron Beam Is a Straight Standard Model Is to Survive Intact
Physics monitor The SLD determination of the confirmed, consistency arguments STANFORD (SLAC) asymmetry parameter using a dictate where this quark can sit if the polarized electron beam is a straight Standard Model is to survive intact. Precision electroweak forward measurement whose errors Using LEP data alone, the top mass result are still dominated by counting is 165 ± 22 GeV, while a global fit to statistics. The systematic error in this all world data yields 178 + 9 + 17-20 measurement (which has dropped to GeV. Precision testing of the electroweak 1.7% from 3.6% in 1992) is due Excitement is high as the next sector of the Standard Model has mainly to the uncertainties in measur round of SLD experiments begins intensified with the recent publica ing the SLC polarization using a this June. With at least 100,000 tion* of results from the SLD collabo Compton polarimeter, situated close events expected and a beam polari ration's 1993 run on the Stanford to the SLC interaction point. zation of about 75 percent, the error Linear Collider, SLC. Using a highly But the 1993 SLD run was not on the final result should be halved. polarized electron beam colliding with without its surprises. Testing the spin With LEP precision improving too, an unpolarized positron beam, SLD transport through the SLC arc to the next year will certainly be inter physicists measured the left-right evaluate an expected chromatic esting for electroweak physics. asymmetry at the Z boson resonance effect on the polarization measure * K. Abe et al, SLAC-PUB-6456 (April with dramatically improved accuracy ment, an SLD group was confronted 1994), submitted to Physical Review over 1992.