Nuclear and Particle Physics

Transcription

1 Nuclear and Particle Physics Second Edition B. R. MARTIN Department of Physics and Astronomy, University College London A John Wiley and Sons, Ltd., Publication

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3 Nuclear and Particle Physics Second Edition

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5 Nuclear and Particle Physics Second Edition B. R. MARTIN Department of Physics and Astronomy, University College London A John Wiley and Sons, Ltd., Publication

6 This edition first published 2009 C 2009 John Wiley & Sons Ltd Registered Office John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Martin, B. R. (Brian Robert) Nuclear and particle physics / B.R. Martin. 2nd ed. p. cm. Includes bibliographical references and index. ISBN (cloth) ISBN (pbk. : alk. paper) 1. Nuclear physics Textbooks. 2. Particles (Nuclear physics) Textbooks. I. Title. QC776.M dc A catalogue record for this book is available from the British Library. ISBN (H/B) (P/B) Set in 10/12pt Times by Aptara Inc., New Delhi, India Printed and bound in Great Britain by Antony Rowe, Ltd, Chippenham, Wiltshire

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9 Contents Preface to the First Edition Preface to the Second Edition Notes xiii xv xvii 1 Basic Concepts History The Origins of Nuclear Physics The Emergence of Particle Physics: the Standard Model and Hadrons Relativity and Antiparticles Space-Time Symmetries and Conservation Laws Parity Charge Conjugation Time Reversal Interactions and Feynman Diagrams Interactions Feynman Diagrams Particle Exchange: Forces and Potentials Range of Forces The Yukawa Potential Observable Quantities: Cross-sections and Decay Rates Amplitudes Cross-sections Unstable States Units: Length, Mass and Energy 28 Problems 29 2 Nuclear Phenomenology Mass Spectroscopy Deflection Spectrometers Kinematic Analysis Penning Trap Measurements Nuclear Shapes and Sizes Charge Distribution Matter Distribution 43

10 viii Contents 2.3 Semi-Empirical Mass Formula: the Liquid Drop Model Binding Energies Semi-empirical Mass Formula Nuclear Instability Radioactive Decay β Decay Phenomenology Odd-mass Nuclei Even-mass Nuclei Fission γ Decays Nuclear Reactions 63 Problems 67 3 Particle Phenomenology Leptons Lepton Multiplets and Lepton Numbers Universal Lepton Interactions: the Number of Neutrinos Neutrinos Neutrino Mixing and Oscillations Oscillation Experiments and Neutrino Masses Lepton Numbers Revisited Quarks Evidence for Quarks Quark Generations and Quark Numbers Hadrons Flavour Independence and Charge Multiplets Quark Model Spectroscopy Hadron Magnetic Moments and Masses 101 Problems Experimental Methods Overview Accelerators and Beams DC Accelerators AC Accelerators Neutral and Unstable Particle Beams Particle Interactions with Matter Short-range Interactions with Nuclei Ionization Energy Losses Radiation Energy Losses Interactions of Photons in Matter Particle Detectors Gas Detectors Scintillation Counters Semiconductor Detectors 133

11 Contents ix Čerenkov Counters Calorimeters Multi-Component Detector Systems 138 Problems Quark Dynamics: The Strong Interaction Colour Quantum Chromodynamics (QCD) Heavy Quark Bound States The Strong Coupling Constant and Asymptotic Freedom Quark-Gluon Plasma Jets and Gluons Colour Counting Deep Inelastic Scattering and Nucleon Structure Scaling Quark-Parton Model Scaling Violations and Structure Functions 170 Problems Weak Interactions and Electroweak Unification Charged and Neutral Currents Symmetries of the Weak Interaction Spin Structure of the Weak Interactions Neutrinos Particles with Mass: Chirality W ± and Z 0 Bosons Weak Interactions of Hadrons: Charged Currents Semileptonic Decays Selection Rules Neutrino Scattering Meson Decays and CP Violation CP Invariance CP Violation in K L 0 Decay CP Violation in B Decays Flavour Oscillations CP Violation and the Standard Model Neutral Currents and the Unified Theory Electroweak Unification The Z 0 Vertices and Electroweak Reactions 210 Problems Models and Theories of Nuclear Physics The Nucleon-Nucleon Potential Fermi Gas Model Shell Model 222

12 x Contents Shell Structure of Atoms Nuclear Magic Numbers Spins, Parities and Magnetic Dipole Moments Excited States Non-Spherical Nuclei Electric Quadrupole Moments Collective Model Summary of Nuclear Structure Models α Decay β Decay Fermi Theory Electron and Positron Momentum Distributions Selection Rules Applications of Fermi Theory γ Emission and Internal Conversion Selection Rules Transition Rates 248 Problems Applications of Nuclear Physics Fission Induced Fission and Chain Reactions Fission Reactors Fusion Coulomb Barrier Fusion Reaction Rates Stellar Fusion Fusion Reactors Nuclear Weapons Fission Devices Fission/Fusion Devices Biomedical Applications Radiation and Living Matter Medical Imaging Using Ionizing Radiation Magnetic Resonance Imaging 289 Problems Outstanding Questions and Future Prospects Overview Hadrons and Nuclei Hadron Structure and the Nuclear Environment Nuclear Structure Nuclear Synthesis Symmetries and the Standard Model The Origin of Mass: the Higgs Boson Theoretical Background 305

13 Contents xi Experimental Searches The Nature of the Neutrino Dirac or Majorana? Neutrinoless Double β Decay Beyond the Standard Model: Unification Schemes Grand Unification Supersymmetry Strings and Things Particle Astrophysics Neutrino Astrophysics The Early Universe: Dark Matter and Neutrino Masses Matter-Antimatter Asymmetry Nuclear Medicine Power Production and Nuclear Waste 333 Appendix A Some Results in Quantum Mchanics 339 A.1 Barrier Penetration 339 A.2 Density of States 341 A.3 Perturbation Theory and the Second Golden Rule 343 A.4 Isospin Formalism 345 A.4.1 Isospin Operators and Quark States 345 A.4.2 Hadron States 347 Appendix B Relativistic Kinematics 351 B.1 Lorentz Transformations and Four-Vectors 351 B.2 Frames of Reference 353 B.3 Invariants 355 Problems 358 Appendix C Rutherford Scattering 361 C.1 Classical Physics 361 C.2 Quantum Mechanics 364 Problems 365 Appendix D Gauge Theories 367 D.1 Gauge Invariance and the Standard Model 367 D.1.1 Electromagnetism and the Gauge Principle 368 D.1.2 The Standard Model 370 D.2 Particle Masses and the Higgs Field 372 Appendix E Data 377 E.1 Physical Constants and Conversion Factors 377 E.2 Tables of Particle Properties 378 E.2.1 Gauge Bosons 378 E.2.2 Leptons 379 E.2.3 Quarks 379

14 xii Contents E.2.4 Low-Lying Baryons 380 E.2.5 Low-Lying Mesons 382 E.3 Tables of Nuclear Properties 384 E.3.1 Properties of Naturally Occurring Isotopes 384 E.3.2 The Periodic Table 392 Appendix F Solutions to Problems 393 References 437 Bibliography 441 Index 443

15 Preface to the First Edition It is common practice to teach nuclear physics and particle physics together in an introductory course and it is for such a course that this book has been written. The material presented is such that different selections can be made for a short course of about lectures depending on the lecturer s preferences and the students backgrounds. On the latter, students should have taken a first course in quantum physics, covering the traditional topics in non-relativistic quantum mechanics and atomic physics. A few lectures on relativistic kinematics would also be useful, but this is not essential, as the necessary background is given in an appendix and is only used in a few places in the book. I have not tried to be rigorous, or present proofs of all the statements in the text. Rather, I have taken the view that it is more important that students see an overview of the subject, which for many, possibly the majority, will be the only time they study nuclear and particle physics. For future specialists, the details will form part of more advanced courses. Nevertheless, space restrictions have still meant that it has been necessarily to make a choice of topics and doubtless other, equally valid, choices could have been made. This is particularly true in Chapter 8, which deals with applications of nuclear physics, where I have chosen just three major areas to discuss. Nuclear and particle physics have been, and still are, very important parts of the entire subject of physics and its practitioners have won an impressive number of Nobel Prizes. For historical interest, I have noted in the footnotes many of these awards for work related to the field. Some parts of the book dealing with particle physics owe much to a previous book, Particle Physics, written with Graham Shaw of Manchester University, and I am grateful to him and the publisher, John Wiley & Sons, Ltd, for permission to adapt some of that material for use here. I also thank Colin Wilkin for comments on all the chapters of the book; to David Miller and Peter Hobson for comments on Chapter 4; and to Bob Speller for comments on the medical physics section of Chapter 8. If errors or misunderstandings still remain (and any such are of course due to me alone) I would be grateful to hear about them. I have set up a website ( brm/npbook.html) where I will post any corrections and comments. Brian R Martin January 2006