The Britannica Guide to Particle Physics

238 Pages·2011·2.926 MB·English

by  Gregersen E. (ed.)

Published in 2011 by Britannica Educational Publishing
(a trademark of Encyclopædia Britannica, Inc.)
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First Edition
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Introduction by Erik Gregersen
Library of Congress Cataloging-in-Publication Data
The Britannica guide to particle physics / edited by Erik Gregersen.
p. cm.—(Physics explained)
“In association with Britannica Educational Publishing, Rosen Educational Services.”
Includes bibliographical references and index.
ISBN (cid:47)(cid:45)(cid:46)(cid:35)(cid:39)(cid:35)(cid:44)(cid:39)(cid:43)(cid:41)(cid:38)(cid:35)(cid:41)(cid:46)(cid:40)(cid:35)(cid:41)(cid:1)(cid:30)(cid:91)(cid:56)(cid:101)(cid:101)(cid:97)(cid:31)
1. Particles (Nuclear physics)—Popular works. I. Gregersen, Erik. II. Title: Guide to par-
ticle physics. III. Title: Particle physics.
QC793.26.B75 2011
539.7'2—dc22
2010030482
Cover, p. iii © www.istockphoto.com/Kasia Biel
On page x: One integral facet of particle physics is string theory, which considers particles
more like “strings” than points, such as strings on a piano. Bloomberg via Getty Images
On page xviii: The Large Hadron Collider (model shown here) may help scientists under-
stand the basic structure of matter. Johannes Simon/Getty Images
On pages 1, 49, 107, 165, 198, 204, 207, 211: The Milky Way Galaxy seems to be completely
made up of matter, as scientists find no evidence of areas where matter and antimatter meet
and extinguish. NASA/CXC/UMass/D. Wang et al., NASA/ESA/STScl/D. Wang et al., NASA/
JPL-Caltech/SSC/S.Stolovy
C
ONTENTS
Introduction x
Chapter 1: Basic Concepts of Particle
Physics 1
The Divisible Atom 2
Size 4
Elementary Particles 5
9
Spin 6
Antiparticles 8
Four Basic Forces 13 22
Field Theory 14
The Basic Forces and Their
Messenger Particles 15
Gravity 15
Electromagnetism 17
The Weak Force 19
The Strong Force 23
Feynman Diagrams 25
Classes of Subatomic Particles 29
Leptons and Antileptons 29
Hadrons 36
Quarks and Antiquarks 44 50
Chapter 2: The Development of
Modern Particle Theory 49
Quantum Electrodynamics:
Describing the Electromagnetic Force 49
Quantum Chromodynamics:
Describing the Strong Force 52
The Nuclear Binding Force 53
“Strangeness” 56
SU(3) Symmetry 57
The Development of Quark
Theory 59
Colour 62
Asymptotic Freedom 64
Electroweak Theory: Describing the
Weak Force 66
Beta Decay 67
A Universal Weak Force 67
Early Theories 69
Hidden Symmetry 73
Finding the Messenger Particles 77
Current Research in Particle Physics 80
76
Experiments 81
Theory 94
103
Chapter 3: Particle Accelerators 107
Principles of Particle Acceleration 107
Generating Particles 108
Accelerating Particles 109
Guiding Particles 111
Colliding Particles 113
Detecting Particles 114
History 115
Constant-Voltage Accelerators 119
Voltage Multipliers (Cascade
Generators) 119
122 Van de Graaff Generators 120
Betatrons 123
Cyclotrons 124
Classical Cyclotrons 125
Synchrocyclotrons 127
Sector-Focused Cyclotrons 128
Linear Resonance Accelerators 129
Linear Electron Accelerators 130
Linear Proton Accelerators 132
Synchrotrons 135
Electron Synchrotrons 138
Proton Synchrotrons 140
Colliding-Beam Storage Rings 142
Electron Storage Rings 144
Proton Storage Rings 146
Electron-Proton Storage Rings 148
Impulse Accelerators 149
Famous Particle Accelerators 149
Argonne National Laboratory 150
CERN and the Large Hadron
Collider 151
DESY 156
Fermi National Accelerator
151
Laboratory 158
SLAC 160
Conclusion 162
Chapter 4: Biographies 165
Patrick M.S. Blackett 165
Sir James Chadwick 167
Owen Chamberlain 168
Sir John Douglas Cockcroft 168
Raymond Davis, Jr. 169
Sheldon Glashow 171
David J. Gross 172
166
William Webster Hansen 173
Gerardus ’t Hooft 175
Koshiba Masatoshi 176 170
Ernest Orlando Lawrence 177
Tsung-Dao Lee 179
Edwin Mattison McMillan 180
Simon van der Meer 181
Yoichiro Nambu 182
H. David Politzer 183
Carlo Rubbia 184
Abdus Salam 185
Emilio Segrè 186
Robert Jemison Van de Graaff 188
Ernest Thomas Sinton Walton 189
Steven Weinberg 190
Frank Wilczek 191
Edward Witten 193
Chen Ning Yang 194
Yukawa Hideki 196
Appendix 198
Degenerate Gas 198
Fermi-Dirac Statistics 199
Hyperon 199
Isospin 200
192
/
J psi Particle 201
Neutron Optics 201
197 Renormalization 203
Glossary 204
Bibliography 207
Index 211