The Discovery of the W and Z Particles
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PRODUCTION of HIGH MASS Cv and E'e' PAIRS in the UA2
142 PRODUCTION OF HIGH MASS cv AND e'e' PAIRS IN THE UA2 EXPERIMENT AT THE CERN pp COLLIDER The UA2 Collaboration (Berne, CERN, CopenhagenT Orsay;" Pavía, Sacïay) Dî 84100S6163 presented by J. SCHACHER University of Berne, Switzerland ABSTRACT We present new results on intermediate vector boson production at the CERN pp collider. A comparison is made with the predictions of the standard model of the unified electroweak Glashow-Salam-Weinberg theory. - 143 - 1, INTRODUCTION We report here the results from a search for electrons with > 15 GeV/c produced at the CERN pp collider (Vs = 540 GeV) during its 1982 and 1983 periods of operation. Following a general discussion of the topology of the events containing an electron candidate, we shall compare the data with expectations in the framework of the electroweak standard model [1] for the reactions p + p - W~ + anything (1) - e" • v (?) p • p - Z° + anything (2) -* e* + e" or e* + e" + y where W~ and Z° are the postulated charged and neutral Intermediate Vector Bosonc (IVB), respectively, According to the amount of data collected we are now in the position to study some details of the IVB production, e.g. the influence of emission of gluon radiation on the distribution of the W transverse momentum (Fig.1). Fig.l Typical diagram for W and Z production, taking into account emission of gluon (g) radiation. 7T : parton in p or p. - 144 - Preliminary results from the study reported here have already been presented elsewhere [2] and a more complete discussion can be found in a recent publication [3]. -
Fabiola Gianotti
Fabiola Gianotti Date of Birth 29 October 1960 Place Rome, Italy Nomination 18 August 2020 Field Physics Title Director-General of the European Laboratory for Particle Physics, CERN, Geneva Most important awards, prizes and academies Honorary Professor, University of Edinburgh; Corresponding or foreign associate member of the Italian Academy of Sciences (Lincei), the National Academy of Sciences of the United States, the French Academy of Sciences, the Royal Society London, the Royal Academy of Sciences and Arts of Barcelona, the Royal Irish Academy and the Russian Academy of Sciences. Honorary doctoral degrees from: University of Uppsala (2012); Ecole Polytechnique Federale de Lausanne (2013); McGill University, Montreal (2014); University of Oslo (2014); University of Edinburgh (2015); University of Roma Tor Vergata (2017); University of Chicago (2018); University Federico II, Naples (2018); Université de Paris Sud, Orsay (2018); Université Savoie Mont Blanc, Annecy (2018); Weizmann Institute, Israel (2018); Imperial College, London (2019). National honours: Cavaliere di Gran Croce dell'Ordine al Merito della Repubblica, awarded by the Italian President Giorgio Napolitano (2014). Special Breakthrough Prize in Fundamental Physics (shared, 2013); Enrico Fermi Prize of the Italian Physical Society (shared, 2013); Medal of Honour of the Niels Bohr Institute, Copenhagen (2013); Wilhelm Exner Medal, Vienna (2017); Tate Medal of the American Institute of Physics for International Leadership (2019). Summary of scientific research Fabiola Gianotti is a particle physicist working at high-energy accelerators. In her scientific career, she has made significant contributions to several experiments at CERN, including UA2 at the proton-antiproton collider (SpbarpS), ALEPH at the Large Electron-Positron collider (LEP) and ATLAS at the Large Hadron Collider (LHC). -
The Second Level Trigger and Dimuon Results
••~ Muonsin UA1; the second level trigger and dimuon results BATS -Data Functional signals /Data )mm; subset AppleTalk. S\S\ IBM 3090 •hard disk keyboard/display • reset button A. L. van Dijk Muons inUAl; the second level trigger and dimuon results ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit van Amsterdam, op gezag van de Rector Magnificus Prof. Dr. P. W. M. de Meijer, in het openbaar te verdedigen in de Aula der Universiteit (Oude Lutherse Kerk, ingang Singel 411, hoek Spui) op dinsdag 26 februari 1991 te 15:00 uur. door Adriaan Louis van Dijk geboren te Amsterdam Promotor: Prof. Dr. J. J. Engelen Co-Promotor: Dr. K. Bos The work described in this thesis is part of the research program of the 'Nationaal Instituut voor Kernfysica en Hoge Energie Fysica (NIKHEFH)'. The author was financially supported by the 'Stichting voor Fundamenteel Onderzoek der Materie (FOM)'. Contents I Introduction 1 1.1 Proton-ontlproton physics, motivation 1 1.2 The CERN proton-antiprolon collider 2 1.3 Collider performance and physics achievements 3 1.4 Jets, muons, heavy flavours and flavour mixing S 1.5 Outline of this thesis 7 II TheUAl Experiment 8 2.1 Introduction 8 2.2 The UA1 coordinate system 10 2.3 Central detector (CD) 11 2.4 The Hadronic Calorimeter 14 2.5 Muon detection system IS 2.6 Triggering and daia acquisition (1987-1990) 18 III Data Acquisition and Triggers 20 3.1 Introduction 20 3.2 Daia acquisition 21 3.2.2 The Event Building 23 3.2.3 Hardware and standards 23 3.2.4 Software 24 3.2.5 Ergonomics 24 3.3 -
1. Discovery of the W and Z Boson 1983 at CERN Spps Accelerator, √S≈540 Gev, UA-1/2 Experiments 1.1 Boson Production in Pp Interactions
Experimental tests of the Standard Model • Discovery of the W and Z bosons • Precision tests of the Z sector • Precision tests of the W sector • Electro-weak unification at HERA • Radiative corrections and prediction of the top and Higgs mass • Top discovery at the Tevatron • Higgs searches at the LHC 1. Discovery of the W and Z boson 1983 at CERN SppS accelerator, √s≈540 GeV, UA-1/2 experiments 1.1 Boson production in pp interactions − − p , q p ,q u W u Z ˆ ˆ d s ν u s +,q p , q p → → ν + → → + pp W X pp Z ff X σ (σ ) 10 nb W Z Similar to Drell-Yan: (photon instead of W) 1nb = ≈ sˆ xq xq s mit xq 12.0 2 1.0 nb = ≈ = 2 sˆ xq s .0 014 s 65( GeV ) → Cross section is small ! sˆ M 1 10 100 W ,Z 1.2 UA-1 Detector 1.3 Event signature: pp → Z → ff + X + p p − High-energy lepton pair: 2 2 2 m = (p + + p − ) = M Z ≈ MZ 91 GeV → → ν + 1.4 Event signature: pp W X Missing p T vector Undetected ν − ν Missing momentum p p High-energy lepton – Large transverse momentum p t How can the W mass be reconstructed ? W mass measurement In the W rest frame: In the lab system: • = = MW p pν • W system boosted 2 only along z axis T ≤ MW • p • p distribution is conserved 2 T −1 2 dN 2p M 2 Jacobian Peak: T ⋅ W − 2 ~ pT pT MW 4 dN dp T • Trans. -
Standard Model and Measurements of Its Parameters (Like the Mass of the Top Quark) at Hadron Colliders Are Presented
Title: Physics at Hadron Colliders Lecturer: Dr Karl Jakobs Date and Times: 1st August at 11:15 2nd August at 10:15 3rd August at 10:15 3rd August at 11:15 Summary of the proposed talk: Present and future hadron colliders play an important role in the investigation of fundamental questions of particle physics. After an introductory lecture, tests of the Standard Model and measurements of its parameters (like the mass of the top quark) at hadron colliders are presented. In addition, it will be discussed how the Higgs boson can be searched for at hadron colliders and how "New Physics", i.e. physics beyond the Standard Model, can be explored. Results are presented from the currently ongoing run at the Tevatron proton antiproton collider at the US research lab Fermilab. In addition, the rich physics potential of the experiments at the CERN Large Hadron Collider is discussed. Prerequisite knowledge and references: - The Standard Model (Lecture by A. Pich) - Beyond the Standard Model (Lecture by E. Kiritsis) Biography- Brief CV: Dr Karl JAKOBS -Studied Physics at the University of Bonn, Germany - Summer student at CERN in 1984 - PhD at the University of Heidelberg, in 1988 Thesis on the UA2-Experiment at the CERN Proton-Antiproton Collider (already Hadron Collider physics at that time) - Fellow and staff position at CERN, UA2 experiment - 1992 - 1996 Max-Planck-Institute for Physics, Munich ALEPH and ATLAS experiments - 1996 - 2003 Prof. of physics at the University of Mainz ALEPH and ATLAS experiments - Since 2000: participation in the D0-Experiment at the Tevatron HR-RFA 07/06 - Since 2003: Prof. -
Antiprotons in the Big Machine
Antiprotons in the big machine Right the beam line which injects 26 GeV antiprotons into the SPS. Centre, the beam fine which sends high energy protons from the SPS towards the West Experimental Area. The main ring is on the left. (Photo CERN 38.4.81) On 7 July a pulse of antiprotons was sent to the CERN Super Proton Synchrotron, accelerated to 270 GeV and (briefly) stored. Two days later the exercise was repeated with greater success and the first evi dence obtained for proton-antipro ton collisions at 540 GeV — by far the highest collision energies ever achieved. Although there is still much to be done before the scheme becomes fully operational, this achievement is a major milestone in the CERN antiproton story. The origins of the project Antiprotons, since they presuma bly have the same properties as protons except for the sign of their electric charge, can be accelerated and stored in the same magnet ring as protons. Thus colliding beam sys tems, like the familiar electron-posi tron machines, are, in principle, fea sible. However until recently it was not possible to produce antiproton tion, the antiprotons emerge with a for colliding beam physics. It in beams of sufficient intensity and wide range of momenta, distinctly volves using electron beams travel density to give sufficient collisions in unsuitable for a magnet system in a ling along with the antiproton beam a reasonable enough time for useful beam transfer line, an accelerator or at the same velocity. The electron physics to be done. a storage ring which is designed to beam, which is much easier to con This situation has changed with handle a well defined particle mo trol, has particles at precisely the the invention of 'beam cooling'. -
Fifty Years of the CERN Proton Synchrotron Volume II
CERN–2013–005 12 August 2013 ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Fifty years of the CERN Proton Synchrotron Volume II Editors: S. Gilardoni D. Manglunki GENEVA 2013 ISBN 978–92–9083–391–8 ISSN 0007–8328 DOI 10.5170/CERN–2013–005 Copyright c CERN, 2013 Creative Commons Attribution 3.0 Knowledge transfer is an integral part of CERN’s mission. CERN publishes this report Open Access under the Creative Commons Attribution 3.0 license (http://creativecommons.org/licenses/by/3.0/) in order to permit its wide dissemination and use. This monograph should be cited as: Fifty years of the CERN Proton Synchrotron, volume II edited by S. Gilardoni and D. Manglunki, CERN-2013-005 (CERN, Geneva, 2013), DOI: 10.5170/CERN–2013–005 Dedication The editors would like to express their gratitude to Dieter Möhl, who passed away during the preparatory phase of this volume. This report is dedicated to him and to all the colleagues who, like him, contributed in the past with their cleverness, ingenuity, dedication and passion to the design and development of the CERN accelerators. iii Abstract This report sums up in two volumes the first 50 years of operation of the CERN Proton Synchrotron. After an introduction on the genesis of the machine, and a description of its magnet and powering systems, the first volume focuses on some of the many innovations in accelerator physics and instrumentation that it has pioneered, such as transition crossing, RF gymnastics, extractions, phase space tomography, or transverse emittance measurement by wire scanners. -
CERN More Protons for Antiprotons
The new DESY-II synchrotron for electrons and positrons, inside the old DESY-l, which will be later rebuilt as DESY-l 11 for a new lease of life injecting protons into the new HERA ring via PETRA. capture more antiprotons for subse quent stacking in the Antiproton Ac cumulator (AA), where the precious particles are stored before being sent into the SPS ring. As well as the ACOL ring (which will surround the AA ring in the exist ing AA hall), improvements are being implemented and other ideas studied all the way down the line. The antiprotons are formed when proton beams strike a target, and one way to get more antiprotons is simply to have more protons hitting the target. However the AA (and lat er ACOL) can only accept single turn injection. As the AA's circumference is only a quarter that of the PS, the proton beam in the PS can only fill a fraction of the machine's circumfer ence before being ejected towards the antiproton production target. The PS is fed in turn by the four ring Booster, and experts have been looking at various schemes to con centrate the PS beam (which normal be used in place of the ceramic one 'new' machine will use the DESY-l ly consists of 20 bunches) by playing needed for the old synchrotron. bending magnets which are of the tricks with the ejection and recombi The installation of components combined function type and, with the nation of the beams from the four will take place in a four-month shut addition of new quadrupoles and Booster rings. -
Supersymmetry: What? Why? When?
Contemporary Physics, 2000, volume41, number6, pages359± 367 Supersymmetry:what? why? when? GORDON L. KANE This article is acolloquium-level review of the idea of supersymmetry and why so many physicists expect it to soon be amajor discovery in particle physics. Supersymmetry is the hypothesis, for which there is indirect evidence, that the underlying laws of nature are symmetric between matter particles (fermions) such as electrons and quarks, and force particles (bosons) such as photons and gluons. 1. Introduction (B) In addition, there are anumber of questions we The Standard Model of particle physics [1] is aremarkably hope will be answered: successful description of the basic constituents of matter (i) Can the forces of nature be uni® ed and (quarks and leptons), and of the interactions (weak, simpli® ed so wedo not have four indepen- electromagnetic, and strong) that lead to the structure dent ones? and complexity of our world (when combined with gravity). (ii) Why is the symmetry group of the Standard It is afull relativistic quantum ®eld theory. It is now very Model SU(3) ´SU(2) ´U(1)? well tested and established. Many experiments con® rmits (iii) Why are there three families of quarks and predictions and none disagree with them. leptons? Nevertheless, weexpect the Standard Model to be (iv) Why do the quarks and leptons have the extendedÐ not wrong, but extended, much as Maxwell’s masses they do? equation are extended to be apart of the Standard Model. (v) Can wehave aquantum theory of gravity? There are two sorts of reasons why weexpect the Standard (vi) Why is the cosmological constant much Model to be extended. -
Measurement of the W-Boson Mass in Pp Collisions at √ S = 7 Tev
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN) Eur. Phys. J. C 78 (2018) 110 CERN-EP-2016-305 DOI: 10.1140/epjc/s10052-017-5475-4 9th November 2018 Measurementp of the W-boson mass in pp collisions at s = 7 TeV with the ATLAS detector The ATLAS Collaboration A measurement of the mass of the W boson is presented based on proton–proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb−1 of integrated luminosity. The selected data sample consists of 7:8 × 106 candidates in the W ! µν channel and 5:9 × 106 candidates in the W ! eν channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yielding mW = 80370 ± 7 (stat.) ± 11 (exp. syst.) ± 14 (mod. syst.) MeV = 80370 ± 19 MeV; where the first uncertainty is statistical, the second corresponds to the experimental system- atic uncertainty, and the third to the physics-modelling systematic uncertainty. A meas- arXiv:1701.07240v2 [hep-ex] 7 Nov 2018 + − urement of the mass difference between the W and W bosons yields mW+ − mW− = −29 ± 28 MeV. c 2018 CERN for the benefit of the ATLAS Collaboration. Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license. 1 Introduction The Standard Model (SM) of particle physics describes the electroweak interactions as being mediated by the W boson, the Z boson, and the photon, in a gauge theory based on the SU(2)L × U(1)Y symmetry [1– 3]. -
Around the Laboratories
Around the Laboratories such studies will help our under BROOKHAVEN standing of subnuclear particles. CERN Said Lee, "The progress of physics New US - Japanese depends on young physicists Antiproton encore opening up new frontiers. The Physics Centre RIKEN - Brookhaven Research Center will be dedicated to the t the end of 1996, the beam nurturing of a new generation of Acirculating in CERN's LEAR low recent decision by the Japanese scientists who can meet the chal energy antiproton ring was A Parliament paves the way for the lenge that will be created by RHIC." ceremonially dumped, marking the Japanese Institute of Physical and RIKEN, a multidisciplinary lab like end of an era which began in 1980 Chemical Research (RIKEN) to found Brookhaven, is located north of when the first antiprotons circulated the RIKEN Research Center at Tokyo and is supported by the in CERN's specially-built Antiproton Brookhaven with $2 million in funding Japanese Science & Technology Accumulator. in 1997, an amount that is expected Agency. With the accomplishments of these to grow in future years. The new Center's research will years now part of 20th-century T.D. Lee, who won the 1957 Nobel relate entirely to RHIC, and does not science history, for the future CERN Physics Prize for work done while involve other Brookhaven facilities. is building a new antiproton source - visiting Brookhaven in 1956 and is the antiproton decelerator, AD - to now a professor of physics at cater for a new range of physics Columbia, has been named the experiments. Center's first director. The invention of stochastic cooling The Center will host close to 30 by Simon van der Meer at CERN scientists each year, including made it possible to mass-produce postdoctoral and five-year fellows antiprotons. -
Particle Physics: Problem Sheet 5 Weak, Electroweak and LHC Physics
2010 — Subatomic: Particle Physics 1 Particle Physics: Problem Sheet 5 Weak, electroweak and LHC Physics 1. Draw a quark level Feynman diagram for the decay K+ → π+π0. This + is a weak decay. K has strange quark number, Ns = −1. The final state has no strange quarks so Ns = 0. The number of strange quarks can only change when a W boson is exchanged. 2. Write down all possible decay modes of the W − boson into quarks and leptons. What is the strength of each of these vertices? Decay Strength − − W → e ν¯e gW − − W → τ ν¯τ gW − − W → µ ν¯µ gW − W → ¯us gW Vus − W → ¯ud gW Vud − W → ¯ub gW Vub − W → ¯cd gW Vcd − W → ¯cs gW Vcs − W → ¯cb gW Vcb − W → ¯t d gW Vtd − W → ¯t s gW Vts − W → ¯t b gW Vtb 3. By drawing the lowest order Feynman diagrams, show that both charged (W ± exchange) and neutral current (Z0 exchange) contribute to neutrino − − electron scattering: νe + e → νe + e . 2010 — Subatomic: Particle Physics 2 Charged current means exchange of the W ± boson, neutral current means exchange of the Z0 boson. Because we can draw both diagrams, whilst obeying all the conservation laws, it means that both are able to happen. When we observe an electron-neutrino scat- tering event we can never tell, on an event-by-event basis, whether the Z-boson or the W -boson was responsilbe. However by measuring the total cross section and comparing with predictions, we can show that both charged and neutral currents are involved.