Elementary-particles physics

Physics Through the 1990s 1
Copyright 2
Preface 7
Contents 9
Executive Summary 17
THE REVOLUTION IN PARTICLE PHYSICS 18
WHAT WE WANT TO KNOW 19
THE TOOLS OF ELEMENTARY-PARTICLE PHYSICS 20
THE FUTURE OF ELEMENTARY-PARTICLE PHYSICS IN THE UNITED STATES 22
RECOMMENDATIONS FOR UNIVERSITY-BASED RESEARCH GROUPS AND USE OF EXISTING FACILITIES IN THE UNITED STATES 23
RECOMMENDATIONS FOR NEW ACCELERATOR FACILITIES IN THE UNITED STATES 23
RECOMMENDATIONS FOR ACCELERATOR RESEARCH AND DEVELOPMENT 24
RECOMMENDATIONS FOR THEORETICAL RESEARCH IN PARTICLE PHYSICS 25
RECOMMENDATIONS FOR NONACCELERATOR PHYSICS EXPERIMENTS 25
RECOMMENDATIONS FOR INTERNATIONAL COOPERATION IN ELEMENTARY-PARTICLE PHYSICS 26
CONCLUSION 26
1 Introduction 27
ELEMENTARY-PARTICLE PHYSICS 28
WHAT WE KNOW 28
WHAT WE WANT TO KNOW 31
THE TOOLS OF ELEMENTARY-PARTICLE PHYSICS 31
THE FUTURE TOOLS OF ELEMENTARY-PARTICLE PHYSICS 32
2 What Is Elementary-Particle Physics? 34
WHAT IS AN ELEMENTARY PARTICLE 35
How Many Kinds of Elementary Particles Are There? 35
The Size of Elementary Particles 39
Elementary Particles and High Energy 39
THE KNOWN BASIC FORCES AND FUNDAMENTAL PARTICLES 41
The Four Basic Forces 41
The Known Families of Elementary Particles 42
The Force-Carrying Particles 43
The Leptons 43
The Quarks 44
The Hadrons 45
Particles and Antiparticles 46
COLLISIONS AND DECAYS 47
Collisions of Particles 47
Collision Diagrams 47
Collisions and Interactions 49
Spontaneous Disintegration of Particles 51
CONSERVATION LAWS AND SYMMETRY IDEAS 51
What Are Conservation Laws? 51
Symmetry and Invariance 52
Symmetry Breaking 55
EXPERIMENTS, ACCELERATIONS, AND PARTICLES DETECTORS 56
Experimental Methods in Elementary-Particle Physics 56
Experiments at Fixed-Target Accelerators 56
Fixed-Target Accelerators 57
Targets 58
Particle Detectors for Charged Particles 58
Secondary Particle Beams 59
Particle Colliders 59
Experiments at Particle Colliders 62
The Decays of Particles 63
Experiments in Elementary-Particle Physics Without Accelerators 63
3 What We Have Learned in the Past Two Decades 64
DEVELOPMENT OF THE QUARK MODEL OF HADRONS 64
The Beginnings of the Quark Model 64
The Discovery of the Charmed Quark 66
Charmonium States 67
DISCOVERY OF THE THIRD GENERATION OF LEPTONS AND QUARKS 69
The Discovery of the Tau Lepton 69
The Discovery of the Bottom Quark 71
The Third Generation 72
HOW QUARKS INTERACT 75
Hadron Interactions 75
Lepton-Proton Scattering Experiments 75
Hadron Jets 78
UNIFICATION OF THE WEAK AND ELECTROMAGNETIC INTERACTIONS 81
STRONG INTERACTION AMONG QUARKS 86
UNIFIED THEORIES 92
4 Elementary-Particle Physics: What We Want To Know 97
INTRODUCTION 97
The Problem of Mass 99
Where Do All These Mass Scales Originate? 101
Composite Quarks and Leptons? 102
Unification of the Fundamental Forces? 102
Interaction of Hadrons 103
USING EXISTING ACCELERATORS AND ACCELERATORS UNDER CONSTRUCTION 103
THE NEED FOR HIGHER-ENERGY ACCELERATORS 107
SOME FUNDAMENTAL ISSUES 112
5 Accelerators for Elementary-Particle Physics 114
INTRODUCTION TO ACCELERATORS 114
The Why and How of Accelerators 114
Particle Colliders 117
Superconducting Magnets in Accelerators 119
Progress in Accelerators and The Energy Frontier 120
ELEMENTARY-PARTICLE PHYSICS AND THE VARIETY OF ACCELERATORS 120
Study of the Properties of Known Particles 120
Study of the Known Forces 122
Tests of New Ideas and Theories 123
The Search for New Particles and the Mass Scale 124
Searches for Clues to Puzzles and Exploration of the Unknown 125
ACCELERATORS WE ARE USING AND BUILDING 126
Proton Accelerators: Fixed Target 127
Proton-Proton and Proton-Antiproton Colliders at CERN 129
The 2-TeV Proton-Antiproton Collider at Fermilab 131
Electron Accelerators: Fixed Target 131
Circular Electron-Positron Colliders 131
The TRISTAN and LEP Electron-Positron Circular Colliders 132
Linear Electron-Positron Colliders 134
Electron-Proton Colliders 136
THE SUPERCONDUCTING SUPER COLLIDER, A VERY-HIGH-ENERGY PROTON-PROTON COLLIDER 136
Physics Goals 136
Collider Goals 137
Design Studies 138
Superconducting Magnets 139
Preliminary Collider Designs and Considerations 140
Schedule and Cost 143
RESEARCH AND DEVELOPMENT FOR VERY-HIGH-ENERGY LINEAR COLLIDERS 144
Physics Motivation 144
Present Technology and Concepts 144
RESEARCH ON ADVANCED CONCEPTS FOR ACCELERATORS AND COLLIDERS 145
Linear Accelerators and Colliders 145
Ultrahigh-Energy Circular Colliders 147
The Need for Advanced Research on Accelerators and Colliders 147
6 Instruments and Detectors for Elementary-Particle Physics 148
INTRODUCTION 148
DETECTOR REQUIREMENTS AND PHYSICAL PRINCIPLES OF DETECTION 151
DETECTORS FOR COLLIDER EXPERIMENTS 155
Close-in Detection: Vertex Detectors 156
Charged-Particle Tracking Chambers 157
Identification of Particle Types 159
Calorimetric Detection and Energy Measurement 159
DETECTORS IN FIXED-TARGET EXPERIMENTS 160
Small or Simple Fixed-Target Experiments 160
Large or Complex Fixed-Target Experiments 163
Bubble Chamber 163
DATA REDUCTION AND COMPUTERS 165
FACILITIES AND DETECTORS FOR EXPERIMENTS NOT USING ACCELERATORS 168
Atomic, Optical, Electronic, and Cryogenic Experiments 168
Experiments Using Radioactive Material or Reactors 168
Experiments Using Cosmic Rays 169
The Solar Neutrino Experiment 171
Searches for the Decay of the Proton 171
SUMMARY AND FUTURE PROSPECTS 172
7 Interactions with Other Areas of Physics and Technology 173
COSMOLOGY AND ASTROPHYSICS 174
COSMIC-RAY PHYSICS 176
NUCLEAR PHYSICS 177
ATOMIC PHYSICS 180
CONDENSED-MATTER THEORETICAL PHYSICS 181
OTHER APPLICATIONS OF ACCELERATORS 182
Synchrotron Radiation 182
Accelerators in Medicine 185
High-Intensity Neutron Sources 185
Accelerators and Plasma Physics 186
LARGE-SCALE USES OF SUPERCONDUCTIVITY 186
SUPPORT AND STIMULATION OF NEW TECHNOLOGY 187
8 Education, Organization, and Decision Making in Elementary-Particle Physics 188
HISTORICAL BACKGROUND 188
Before 1960 188
After 1960 in the United States 189
After 1950 Abroad 191
PACE AND PLANNING IN ACCELERATOR CONSTRUCTION AND USE 192
Conception 192
Proposal 193
Decision 193
Construction 193
Use of Accelerators for Physics 194
The Death of an Accelerator 194
SUMMARY 195
THE NATURE OF ELEMENTARY-PARTICLE PHYSICS EXPERIMENTATION 195
GRADUATE EDUCATION 197
INTERACTION BETWEEN THE PARTICLE-PHYSICS COMMUNITY AND THE FEDERAL GOVERNMENT 198
Universities 198
Accelerator Laboratories 199
Decision Making and Advice 199
INTERNATIONAL COOPERATION AND COMPETITION 201
FUTURE TRENDS AND ISSUES 205
Graduate Students' Role 205
Scientific Manpower in Particle Physics 205
Advanced Accelerator and Detector Research 206
Laboratory Management 208
Advisory Structure 209
9 Conclusions and Recommendations 210
THE REVOLUTION OF THE PAST TWO DECADES 210
HOW THE REVOLUTION WAS MADE 211
WHAT WE WANT TO KNOW 211
RECOMMENDATIONS FOR UNIVERSITY-BASED RESEARCH GROUPS AND USE OF EXISTING FACILITIES IN THE UNITED STATES 212
RECOMMENDATIONS FOR NEW ACCELERATOR FACILITIES IN THE UNITED STATES 213
RECOMMENDATIONS FOR ACCELERATOR RESEARCH AND DEVELOPMENT 214
RECOMMENDATIONS FOR THEORETICAL RESEARCH IN PARTICLE PHYSICS 214
RECOMMENDATIONS FOR NONACCELERATOR PHYSICS EXPERIMENTS 215
RECOMMENDATIONS FOR INTERNATIONAL COOPERATION IN ELEMENTARY-PARTICLE PHYSICS 215
CONCLUSION 216
Appendixes 217
A The World's High-Energy Accelerators 219
B Particle Colliders Under Construction 223
C Statistical Information on Elementary-Particle Physics Research in the United States 225
Physicists and Graduate Students in Elementary-Particle Physics 225
Funding for Elementary-Particle Physics Research 225
Glossary 229
Index 239