Large Hadron Collider

12 Key excerpts on "Large Hadron Collider"

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  LHC Physics

  • T. Binoth, C. Buttar, P. J. Clark, E.W.N. Glover(Authors)
  • 2012(Publication Date)
  • CRC Press

    (Publisher)

  Section II: The Large Hadron Collider This page intentionally left blank This page intentionally left blank 179 The LHC Accelerator: Performance and Technology Challenges Philippe Lebrun CERN, Geneva, Switzerland 1 Introduction The Large Hadron Collider (LHC), now operating for physics at CERN, the European Laboratory for Particle Physics in Geneva (Switzerland), is the largest scientific instrument in the world. It accelerates intense proton and ion beams up to energies of 7 TeV (protons) or 2.759 TeV/nucleon (Pb ions), and brings them into collision at the heart of four large detectors located around its 26.7 km circumference (Figure 1). The twin accelerators are composed of eight arcs, 2987 m long, connected via 528-m-long straight sections. At the transition between arcs and straight sections, dispersion suppressors cancel horizontal dispersion arising in the arcs and help match the optics. In order to guide and focus its very rigid beams, the LHC makes use of several thousand high-field superconducting magnets, operating in superfluid helium below 2 K. Although well above the preceding state-of-the-art in terms of beam energy and luminosity, the LHC is built on the knowledge and experience gained at previous high-energy accelerators: physics of hadron colliders was developed at the CERN ISR, the SPS antiproton collider and the TeVatron at Fermilab, while the TeVatron, HERA at DESY, RHIC at Brookhaven National Labo-ratory and CEBAF at Thomas Jefferson National Laboratory pioneered the technology of superconducting accelerators and the use of superfluid helium cooling. In the following we will try and demonstrate how the performance require-ments of the LHC drive its technological choices, and conversely how advanced technology permits unprecedented performance within affordable boundary conditions and constraints. The most important such constraint was the re-use of the large tunnel which had previously housed the LEP electron-positron

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  Reviews Of Accelerator Science And Technology - Volume 3: Accelerators As Photon Sources

  Volume 3: Accelerators as Photon Sources

  • Alexander Wu Chao, Weiren Chou(Authors)
  • 2011(Publication Date)
  • World Scientific

    (Publisher)

  Reviews of Accelerator Science and Technology Vol. 3 (2010) 261– 280 c World Scientific Publishing Company DOI: 10.1142/S1793626810000373 The Large Hadron Collider from Conception to Commissioning: A Personal Recollection Lyndon Evans CERN, Meyrin, CH-1211, Geneva 23, Switzerland and Imperial College London, London SW7 2HZ, UK [email protected] It is generally accepted that the birth of the Large Hadron Collider (LHC) was in the Lausanne Workshop in 1984 [1], where machine builders and experimentalists first got together to discuss the next big project for CERN. In reality, the seeds were sown much earlier, with the construction of the Intersecting Storage Rings at CERN, followed by the proton–antiproton colliders at CERN and at Fermilab. In this article I try to give a historical perspective on how the LHC came to be, as well as my own account of some of the political, technical and financial challenges that had to be met in order to make it a reality. Keywords : Large Hadron Collider (LHC); CERN; accelerator; collider; superconducting magnet. 1. Introduction The construction of the Large Hadron Collider (LHC) has been a massive endeavor, spanning almost 30 years from conception to commissioning. Building the machine with the highest possible energy (7 TeV) in the existing LEP tunnel of 27 km circumference and with a tunnel diameter of only 3.8 m has required considerable innovations. The first was the develop-ment of an idea first proposed by Bob Palmer at BNL in 1978, where the two rings are integrated into a sin-gle magnetic structure. This compact 2-in-1 struc-ture was essential for the LHC, due to the limited space available in the existing LEP tunnel and the cost. The second was a bold move to employ super-fluid helium cooling on a massive scale, which was imposed by the need to achieve a high (8.3 T) mag-netic field using an affordable Nb–Ti superconductor. In this article, no attempt is made to provide a comprehensive review of the machine design.

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  Discovery of the Higgs Boson

  • Aleandro Nisati, Vivek Sharma(Authors)
  • 2016(Publication Date)
  • WSPC

    (Publisher)

  Chapter 4

  Overview of the Large Hadron Collider and of the ATLAS and CMS experiments

  Aleandro Nisati* and Vivek Sharma†

  * INFN, Sezione di Roma P.le A. Moro 2, Rome 00185, Italy † University of California San DiegoLa Jolla, California, 92093, USA

  The Large Hadron Collider is the most powerful particle accelerator ever built. It has allowed the discovery of a Higgs boson with mass near 125 GeV in 2012 by the ATLAS and CMS experiments. This chapter provides first an overview of the main characteristics of this collider, as well as a short description of the two general purpose experiments, ATLAS and CMS, which discovered in 2012 a Higgs boson with mass close to 125 GeV. This is followed by a summary of the main aspects of particle identification and reconstruction by these two detectors, together with a short presentation of the main analysis tools used to extract the LHC results of the Higgs boson(s) searches and measurements.

  1.The Large Hadron Collider: Machine and experiments

  The Large Hadron Collider (LHC) is to date the largest and highest-energy particle accelerator in the world. Although the idea of a Large Hadron Collider had been around since at least 1977, it is generally accepted that the birth of the LHC was in the Lausanne Workshop in 1984.1 The proposal was to install this new machine in the LEP tunnel (see Chapter 2 ), once the scientific programme of this electron–positron collider was completed. Approved by the CERN Council in December 1996, the construction of this accelerator started in 1998 and lasted about ten years. A nice recollection is available in Ref. [2 ].

  This machine has been designed primarily to collide protons at a center-of-mass energy = 14 TeV with a nominal instantaneous luminosity = 1 ×1034 cm−2 s−1 and a bunch-spacing of 25 ns. Details on the design can be found in Refs. [3 –5

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  A User's Guide to the Universe

  Surviving the Perils of Black Holes, Time Paradoxes, and Quantum Uncertainty

  • Dave Goldberg, Jeff Blomquist(Authors)
  • 2010(Publication Date)
  • Trade Paper Press

    (Publisher)

  On the surface of it, the LHC does look like a doomsday device: it’s a giant underground ring seventeen miles in circumference—so large, in fact, that it crosses the French-Swiss border four times. You can think of the LHC as a light-speed monster truck rally in which particles are accelerated up to 99.999999% of the speed of light 56 and then smashed into one another. As we saw in chapter 1, energy and mass are interchangeable, so at these tremendous speeds a bunch of high-mass particles are created. The LHC is the biggest advance in particle collisions in recent history, and the fear is that one of the things created by these collisions might spell doom for humanity. Except that it hasn’t. First, while “particle accelerator” sounds scary, this is not new technology. If you’ve ever used an old-style television, you’ve seen a simple particle accelerator at work. The old sets used cathode ray tubes to accelerate electrons, and by adjusting the position of the beam, magical moving pictures were created on your screen. The mechanism inside the LHC is somewhat different, but just as with television, particle accelerators can be illuminating and terrifying. 57 So which is it? Is the LHC another important step toward our ultimate understanding of nature or, like Icarus, are we flying too close to the Sun? Will we be punished for our arrogant pursuit of knowledge? Rest assured, nobody is in danger of losing an eye. How do we know? Settle in for a while, because before we figure out why the LHC doesn’t pose any danger, we have to figure out why we’re building it in the first place. What do we need a multibillion-dollar accelerator for, anyway? In high school physics, everything seemed like a hodgepodge of arbitrary rules: do this calculation if you have a pulley; do this other thing if you have an inclined plane; do this third thing if there is acceleration; and on and on, down the line

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  Large Hadron Collider, The: The Greatest Adventure In Town And Ten Reasons Why It Matters, As Illustrated By The Atlas Experiment

  The Greatest Adventure in Town and Ten Reasons Why it Matters, as Illustrated by the ATLAS Experiment

  • Andrew J Millington, Markus Nordberg, Thorsten Wengler(Authors)
  • 2016(Publication Date)
  • World Scientific Publishing Europe Ltd

    (Publisher)

  The driver of everything is the ageless quest for understanding at a fundamental level of what are the key constituents of matter, into what intellectual framework do they fit, and how can we detect them beyond reasonable doubt. So, in this first chapter we’ll explore why the physics led CERN to build the Large Hadron Collider, how the engineering, cost and politics came together to make it happen, and how the ATLAS experi-ment sought to pin down the elusive particles predicted to appear at the new energies achievable at the LHC. How the ATLAS Experiment Happened The constraints on achieving a viable accelerator and detector are huge. The scale of the Large Hadron Collider itself is governed by the need to speed The Physics Itself and Why it Needed the LHC 3 up the proton beams to very close to the speed of light. Being charged par-ticles (a proton is the positively charged nucleus of the hydrogen atom) they can be accelerated by electromagnetic fields, but the faster they go the harder the beam is to bend. Charged particles give off electromagnetic radiation when their paths are changed, so the accelerator ring has to be as gentle a bend as possible to limit this and the corresponding force needed to keep the beam in circuit. It becomes a trade-off between accelerator size and the strength of bending force required. But this circular geometry allows identical beams to be sent in opposite directions around the ring. The beams can then be made to collide at specific points chosen for the detectors. Similar arguments of scale apply to the detectors. A detector like ATLAS has to measure the energies and trajectories of particles cre-ated as the proton beams or bunches collide. These resulting particles also travel at high speeds so powerful magnets are needed again to bend their paths and help identify their energies and origins.

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  The Particle at the End of the Universe

  Winner of the Royal Society Winton Prize

  • Sean Carroll(Author)
  • 2012(Publication Date)
  • Oneworld Publications

    (Publisher)

  In retrospect, the accident in September 2008 helped the physicists and technicians at the LHC understand their machine much better, and as a result, the physics runs beginning in 2010 were stories of essentially uninterrupted progress. Given that operations didn’t start in earnest until that year, it came as a surprise to almost everybody that the experiments collected and analyzed enough data to discover the Higgs by July 2012. It’s as if you purchased an expensive car that breaks down almost immediately, and you have to spend a while combating some pesky maintenance problems. But once you finally get it on the road and hit the accelerator, the performance takes your breath away.

  The Large Hadron Collider is Big Science at its biggest. The number of moving parts—human as well as mechanical—can sometimes be intimidating, or even depressing. In the words of Nobel Laureate Jack Steinberger, “The LHC is a symbol of just how difficult it is these days to make any progress. What a difference when compared to my thesis days, sixty-five years ago, when I, singlehandedly, in half a year, could do an experiment which marked an interesting step forward.” The LHC is the largest and most complicated machine ever built by human beings, and sometimes it’s a surprise that it works at all.

  But it does work—spectacularly well. Over and over again, physicists I talked to while writing this book spoke of the awe-inspiring immensity of the operation, but also about how CERN could serve as a model for large-scale international collaboration. Experimentalist Joe Incandela said, “What’s amazing to me is that we have people from seventy countries around the world working—together. Palestinians and Israelis working side by side, Iranians and Iraqi scientists work together—such collaborations in the pursuit of Big Science shouldn’t be overlooked.” Joe Lykken, an American theoretical physicist at Fermilab, wistfully mused, “If only the United Nations could work like CERN, the world would be a much better place.”

  If you believe that it’s a worthwhile task to pursue particles like the Higgs boson that require a huge amount of energy to create, Big Science is the only way to go. There is a tremendous amount of fantastic research to be done that can be tackled with relatively inexpensive tabletop experiments, but discovering new massive particles isn’t in that category. Right now the LHC is the only game in town, and its performance is a testimony to human ingenuity and perseverance.

  Years of Planning

  The LHC is a marvel of planning and design. Physicists at CERN had been thinking about a giant proton collider for a while, but the first “official” discussions about what would eventually become the LHC were held at a workshop in Lausanne, Switzerland, in March 1984. The planners knew that the United States was contemplating what would eventually become the Superconducting Super Collider, so they needed to decide whether a European competitor was a sensible use of scarce resources. (They didn’t know, of course, that the SSC would eventually be canceled.) Unlike the SSC, which started from scratch building a new facility, the LHC would be limited in scope by the need to fit inside the already-constructed LEP tunnel. As a result, the target energy was set at 14 TeV, barely more than one-third of the 40 TeV target for the SSC. But the LHC would be able to produce more collisions per second, and was less expensive—and maybe all the good physics would be accessible at 14 TeV, rendering the higher energy of the SSC irrelevant.

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  The Large Hadron Collider

  The Greatest Adventure in Town and Ten Reasons Why it Matters, as Illustrated by the ATLAS Experiment

  • Andrew J Millington, Markus Nordberg;Thorsten Wengler;Rob McPherson;(Authors)
  • 2016(Publication Date)
  • WSPC (EUROPE)

    (Publisher)

  The driver of everything is the ageless quest for understanding at a fundamental level of what are the key constituents of matter, into what intellectual framework do they fit, and how can we detect them beyond reasonable doubt. So, in this first chapter we’ll explore why the physics led CERN to build the Large Hadron Collider, how the engineering, cost and politics came together to make it happen, and how the ATLAS experiment sought to pin down the elusive particles predicted to appear at the new energies achievable at the LHC.

  How the ATLAS Experiment Happened

  The constraints on achieving a viable accelerator and detector are huge. The scale of the Large Hadron Collider itself is governed by the need to speed up the proton beams to very close to the speed of light. Being charged particles (a proton is the positively charged nucleus of the hydrogen atom) they can be accelerated by electromagnetic fields, but the faster they go the harder the beam is to bend. Charged particles give off electromagnetic radiation when their paths are changed, so the accelerator ring has to be as gentle a bend as possible to limit this and the corresponding force needed to keep the beam in circuit. It becomes a trade-off between accelerator size and the strength of bending force required. But this circular geometry allows identical beams to be sent in opposite directions around the ring.

  The beams can then be made to collide at specific points chosen for the detectors. Similar arguments of scale apply to the detectors. A detector like ATLAS has to measure the energies and trajectories of particles created as the proton beams or bunches collide. These resulting particles also travel at high speeds so powerful magnets are needed again to bend their paths and help identify their energies and origins. So how did the physicists identify the critical size and parameters for the LHC and its experiments? How did the demands of the physics shoe in with the technological constraints and the cost?

  In this book, we don’t intend to go in depth into the physics. There are many papers and publications which do that. What we aim to do is to give an overview of the physics to aid an appreciation of the whole enterprise. This includes the cultural impact of the physics on society at large. Our intention here is to show the many faceted nature of the ATLAS experiment in the context of the wider CERN and particle physics world. For those who contend that the search for the Higgs boson and other new particles may be exciting, but it’s expensive when there are many more pressing practical problems, we will show that the upfront cost is a poor guide to value as so much else flows from the ATLAS/CERN endeavour. But the gains from building the 27 kilometre accelerator and its big detectors have not been widely trumpeted, and certainly not as a coherent presentation. So that’s where we’re coming from.

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  Engines of Discovery

  A Century of Particle Accelerators

  • Andrew Sessler, Edmund Wilson(Authors)
  • 2014(Publication Date)
  • WSPC

    (Publisher)

  Z at CERN had been to start design and construction of the SSC, a proton-proton collider 20 times more powerful than the Tevatron but this had proved too costly even for the US science budget and was terminated in mid-construction. We were left with the “Large Hadron Collider” or LHC as the way forward.

  Fig. IX.2 A picture showing the cross section of the superconducting magnets for the Large Hadron Collider (LHC) at CERN. LHC collides protons on protons and therefore has two beams, each with its own beampipe, except near the interaction points, and its own set of magnetic coils.

  IX.2   The Large Hadron Collider (LHC)

  The sheer size and cost of this enterprise was to be without parallel and had it been built on a “green field site” it likely would have had the same fate as the SSC. LEP was shut down and removed from its tunnel on the CERN site to make room for the new collider. The LHC could be fed by the chain of accelerators that already existed on the site. Nevertheless it is an ambitious machine, for in order to reach 7 TeV in the 27 km LEP tunnel, the magnetic field had to be close to 9 tesla. This is five times the field at which a normal magnet saturates and more than 50% higher than that for which previous accelerators such as the SSC had been designed. Only superconducting magnets can provide this field (see sidebar for Superconducting Magnets in Chapter V ).

  LHC is a conventional two-ring interlaced proton-proton collider like the ISR, but rather than two separate magnet rings and their cryostats it uses the more ingenious solution of putting both beam pipes in the same magnet and cryostat. The magnet cross section of the 7 TeV hadron collider is shown in Fig. IX.2 . The proton beams have the same polarity but go around in opposite directions. Thus, although they share a magnetic yoke, they circulate in separate pipes, guided by separate superconducting coils, providing a vertical magnetic field of opposite sign in the two pipes. The construction project was led by Lyn Evans (see sidebar for Evans) and the repair, exploitation and operation of the machine by Steve Myers (see sidebar for Myers).

  The LHC started up in spectacular fashion on 10 September 2008. With the confidence of many successful projects behind them, the CERN team had decided to press the button to the machine under the eyes of the world’s media. Although it was a common practice for the launch of space vehicles, this was a “first” in the world of particle physics. The ensuing public relations event, second to none in particle physics, had been prepared in the days before in broadcasts by the world’s most eloquent journalists. As the start-up approached, TV viewers could not claim to be ignorant of the aims of the project or of its importance for our understanding of the origins of the universe. Every available expert in particle physics was wheeled out to face cameras. Some, less expert than others and possessing only “that little knowledge that is a dangerous thing”, predicted that LHC collisions might trigger a black hole to swallow up the planet. Though CERN was quick to reassure everyone that this could not happen, the uncertainty served only to intensify the interest and to ensure that a huge audience was perched on the edge of their chairs for the countdown.

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  String Theory And Its Applications (Tasi 2010): From Mev To The Planck Scale - Proceedings Of The 2010 Theoretical Advanced Study Institute In Elementary Particle Physics

  TASI 2010From meV to the Planck Scale

  • Michael Dine, Thomas Banks, Subir Sachdev(Authors)
  • 2011(Publication Date)
  • World Scientific

    (Publisher)

  LHC Physics This page intentionally left blank This page intentionally left blank Chapter 3 Fundamentals of LHC Experiments Jason Nielsen Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064, USA [email protected] Experiments on the Large Hadron Collider at CERN represent our fur-thest excursion yet along the energy frontier of particle physics. The goal of probing physical processes at the TeV energy scale puts strict requirements on the performance of accelerator and experiment, dictat-ing the awe-inspiring dimensions of both. These notes, based on a set of five lectures given at the 2010 Theoretical Advanced Studies Institute in Boulder, Colorado, not only review the physics considered as part of the accelerator and experiment design, but also introduce algorithms and tools used to interpret experimental results in terms of theoretical models. The search for new physics beyond the Standard Model presents many new challenges, a few of which are addressed in specific examples. 3.1. Introduction Experimental results combined with theoretical considerations imply the existence of new physics beyond the Standard Model, at energies no greater than 1 TeV. Although this has been known for a while [1], the possibility of accessing this energy scale, known as the “terascale,” has now been realized in current-day hadron colliders and the experiments that use them. These notes provide a brief overview of the experimental considerations and design needed to measure particle interactions at the terascale. To probe directly the physics at the 1 TeV scale, we need a momentum transfer Q 2 of approximately 1 TeV between the initial state particles. This direct requirement assumes we are most interested in producing real (on-shell) new particles. There is still a role, of course, for precision experiments on the intensity frontier that measure the effects of off-shell new particles 127

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  Physics at the Terascale

  • Ian Brock, Thomas Schörner-Sadenius(Authors)
  • 2011(Publication Date)
  • Wiley-VCH

    (Publisher)

  Part Two The Technology Passage contains an image Chapter 12 Accelerators: the Particle Smashers Helmut Burkhardt, Jean-Pierre Delahaye and Günther Geschonke 12.1Introduction

  Experimental elementary particle physics at the high energy frontier is done largely with powerful particle accelerators: charged particles are accelerated to very high energies and brought into collision either with a fixed target or with particles of a second beam, travelling in the opposite direction. The latter method is used for the highest centre-of-mass collision energies and these machines are generally referred to as colliders . In these collisions, either all or a fraction of the energy of the particles is available to create new particles. In LEP, for example, the colliding particles had an energy more than 200 000 times their rest energy! The major machines today either accelerate leptons (electrons/positrons) or hadrons (protons/antiprotons and ions up to lead). Often these machines are built as storage rings , where the two counter-rotating high energy beams are kept circulating and the same beams can be brought into collision at each revolution. Since only a very small fraction of the particles actually collide in each crossing and the loss of particles due to other mechanisms, like collisions with the residual gas in the vacuum chambers, can be made small, the beams can be stored for many hours.

  In the following, we present a few examples of accelerators at the present state of the art with their technology and performance. Finally, we sketch the work in progress for even higher energies.

  Within the scope of this book it is impossible to give a comprehensive review of all existing machines, which would easily fill a book on its own. We rather highlight some features of the state of the art of major high energy machines. As examples we use LEP, the Large Electron–Positron collider (CERN, 1989–2000), the electron–proton collider HERA (DESY, 1992–2007), the proton–antiproton collider Tevatron (Fermilab, in operation since 1987), and the LHC, Large Hadron Collider (CERN, in operation since 2008). Finally we also discuss the possible future linear colliders ILC and CLIC.

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  Fundamental Interactions - Proceedings Of The 22nd Lake Louise Winter Institute

  • Alan Astbury, Faqir C Khanna, Roger W Moore(Authors)
  • 2007(Publication Date)
  • World Scientific

    (Publisher)

  LHC TO ILC BARRY C BARISH Caltech Pasadena, CA @or the ILC Collaboration) 1. Introduction and Physics Introduction In these three lectures, I introduce the International Linear Collider, briefly discuss the physics goals, and describe the present concepts for the machine and detectors. The timing of these lectures is almost coincident with the release of draft versions of the Reference Design Report (RDR) for the machine and Detector Concept Report (DCR) for the detectors. These will be finalized during the summer of 2007, and then we will undertake to do an engineering design for both the machine and (probably) two detectors over the next three years. That will bring us to a position where we ready to submit a construction proposal at about the time we anticipate and hope there will be significant results from the LHC. Much of the materials of this write-up are extracted from those reports, especially the Executive Summary. More complete descriptions of both the machine design and detector concepts can be found in those reports. The LHC will soon begin a new era in particle physics by opening up the TeV scale to experimental studies. We have very good reason to expect both expected and unexpected new physics. The energy frontier has been our most productive way to learn new particle physics for three generations of machines, for electrons first at SPEAR, then DESY and finally at SLC and LEP. In this talk, I present the case, the concepts and status of the efforts to develop a fourth generation electron positron collider, the International Linear Collider, to complement the LHC in our pursuit of Terascale physics. The Physics of the ILC Many scientific opportunities for the ILC involve the Higgs particle and related new phenomena at Terascale energies. The Higgs is central to a broad program of discovery. The first question, of course, is whether there really is a Higgs or some other mechanisms that give mass to particles and 1

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  Critical Problems in Physics

  • Val L. Fitch, Daniel R. Marlow, Margit A.E. Dementi, Val L. Fitch, Daniel R. Marlow, Margit A.E. Dementi, Margit A.E. De menti(Authors)
  • 2021(Publication Date)
  • Princeton University Press

    (Publisher)

  CHAPTER 12 HIGH ENERGY COLLIDERS R.B. PALMER AND J.C. GALLARDO Center for Accelerator Physics Brookhaven National Laboratory, Upton, NY ABSTRACT We consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, pp), lepton (e+e~, fJ. + [i~) and photon-photon col-liders. Technical problems in obtaining increased energy in each type of machine are presented. The relative sizes of the machines are also discussed. 12.1 INTRODUCTION Particle colliders are only the latest evolution of a long history of devices used to study the violent collisions of particles on one another. Earlier versions used accelerated beams impinging on fixed targets. Fig. 12.1 shows the equivalent beam energy of such machines, plotted versus the year of their introduction. The early data given was taken from the original plot by Livingston [1]. For hadron, i.e., proton or proton-antiproton, machines (Fig. 12.1a), it shows an increase from around 10 5 eV with a rectifier generator in 1930, to 10 15 eV at the Tevatron (at Fermilab near Chicago) in 1988. This represents an increase of more than a factor of about 33 per decade (the Livingston line, shown as the dashed line) over 6 decades. By 2005 we expect to have the Large Hadron Collider (at CERN, Switzerland) with an equivalent beam energy of 10 17 eV, which will almost ex-actly continue this trend. The SSC, had we built it on schedule, would, by this extrapolation, have been a decade too early! The rise in energy of electron machines shown (Fig. 12.1b) is slightly less dramatic; but, as we shall discuss below, the relative effective physics energy of 247 248 CHAPTER 12. HIGH ENERGY COLLIDERS lepton machines is greater than for hadron machines, and thus the effective energy gains for the two types of machine are comparable.

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