Nuclear Physics E-Book

John Lilley

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: The Manchester Physics Series
• Sprache: Englisch

Seitenzahl: 752

Veröffentlichungsjahr: 2013

Beschreibung

This title provides the latest information on nuclear physics. Based on a course entitled Applications of Nuclear Physics. Written from an experimental point of view this text is broadly divided into two parts, firstly a general introduction to Nuclear Physics and secondly its applications.

• Includes chapters on practical examples and problems
• Contains hints to solving problems which are included in the appendix
• Avoids complex and extensive mathematical treatments
• A modern approach to nuclear physics, covering the basic theory, but emphasising the many and important applications

Leseprobe

Contents

Flow diagram

Editors’ preface to the Manchester Physics Series

Author’s preface

PART I PRINCIPLES

1 INTRODUCTION AND BASIC CONCEPTS

1.1 INTRODUCTION

1.2 EARLY DISCOVERIES

1.3 BASIC FACTS AND DEFINITIONS

1.4 NUCLEAR POTENTIAL AND ENERGY LEVELS

1.5 RADIOACTIVITY AND RADIOACTIVE DECAY

1.6 NUCLEAR COLLISIONS

PROBLEMS 1

2 NUCLEAR STRUCTURE

2.1 INTRODUCTION

2.2 NUCLEAR MASS

2.3 NUCLEAR SHELL MODEL

2.4 SINGLE-PARTICLE FEATURES

2.5 COLLECTIVE STATES

PROBLEMS 2

3 NUCLEAR INSTABILITY

3.1 INTRODUCTION

3.2 GAMMA EMISSION

3.3 BETA DECAY

3.4 ALPHA DECAY

PROBLEMS 3

4 NUCLEAR REACTIONS

4.1 INTRODUCTION

4.2 GENERAL FEATURES OF NUCLEAR REACTIONS

4.3 ELASTIC SCATTERING AND NUCLEAR SIZE

4.4 DIRECT REACTIONS

4.5 COMPOUND NUCLEUS REACTIONS

4.6 HEAVY-ION REACTIONS

PROBLEMS 4

PART II INSTRUMENTATION AND APPLICATIONS

5 INTERACTION OF RADIATION WITH MATTER

5.1 INTRODUCTION

5.2 HEAVY CHARGED PARTICLES

5.3 ELECTRONS

5.4 GAMMA RAYS

5.5 NEUTRONS

PROBLEMS 5

6 DETECTORS AND INSTRUMENTATION

6.1 INTRODUCTION

6.2 GAS DETECTORS

6.3 SCINTILLATION DETECTORS

6.4 SEMICONDUCTOR DETECTORS

6.5 DETECTOR PERFORMANCE FOR GAMMA RAYS

6.6 NEUTRON DETECTORS

6.7 PARTICLE IDENTIFICATION

6.8 ACCELERATORS

PROBLEMS 6

7 BIOLOGICAL EFFECTS OF RADIATION

7.1 INTRODUCTION

7.2 INITIAL INTERACTIONS

7.3 DOSE, DOSE RATE AND DOSE DISTRIBUTION

7.4 DAMAGE TO CRITICAL TISSUES

7.5 HUMAN EXPOSURE TO RADIATION

7.6 RISK ASSESSMENT

PROBLEMS 7

8 INDUSTRIAL AND ANALYTICAL APPLICATIONS

8.1 INTRODUCTION

8.2 INDUSTRIAL USES

8.3 NEUTRON ACTIVATION ANALYSIS

8.4 RUTHERFORD BACKSCATTERING

8.5 PARTICLE-INDUCED X-RAY EMISSION

8.6 ACCELERATOR MASS SPECTROMETRY

8.7 SIGNIFICANCE OF LOW-LEVEL COUNTING

PROBLEMS 8

9 NUCLEAR MEDICINE

9.1 INTRODUCTION

9.2 PROJECTION IMAGING: X-RADIOGRAPHY AND THE GAMMA CAMERA

9.3 COMPUTED TOMOGRAPHY

9.4 POSITRON EMISSION TOMOGRAPHY

9.5 MAGNETIC RESONANCE IMAGING

9.6 RADIATION THERAPY

PROBLEMS 9

10 POWER FEOM FISSION

10.1 INTRODUCTION

10.2 CHARACTERISTICS OF FISSION

10.3 THE CHAIN REACTION IN A THERMAL FISSION REACTOR

10.4 THE FINITE REACTOR

10.5 REACTOR OPERATION

10.6 COMMERCIAL THERMAL REACTORS

10.7 FUTURE OF NUCLEAR FISSION POWER

PROBLEMS 10

11 THERMONUCLEAR FUSION

11.1 INTRODUCTION

11.2 THERMONUCLEAR REACTIONS AND ENERGY PRODUCTION

11.3 FUSION IN A HOT MEDIUM

11.4 PROGRESS TOWARDS FUSION POWER

11.5 FUSION IN THE EARLY UNIVERSE

11.6 STELLAR BURNING

11.7 NUCLEOSYNTHESIS BEYOND A ≈ 60

PROBLEMS 11

APPENDIX A: Useful Information

A.1 PHYSICAL CONSTANTS1 AND DERIVED QUANTITIES

A.2 MASSES AND ENERGIES

A.3 CONVERSION FACTORS

A.4 USEFUL FORMULAE

APPENDIX B: Particle in a Square Well

APPENDIX C: Density of States and the Fermi Energy

C.1 DENSITY OF STATES

C.2 FERMI ENERGY

APPENDIX D: Spherical Harmonics

APPENDIX E: Coulomb Scattering

APPENDIX F: Mass Excesses and Decay Properties of Nuclei

APPENDIX G: Answers and Hints to Problems

CHAPTER 1

CHAPTER 2

CHAPTER 3

CHAPTER 4

CHAPTER 5

CHAPTER 6

CHAPTER 7

CHAPTER 8

CHAPTER 9

CHAPTER 10

CHAPTER 11

References

Bibliography

Index

Flow diagram

The solid lines leading to a chapter indicate the earlier chapters of which substantial knowledge is presupposed.

The dashed line indicates that Chapter 6 contains some material referred to in Chapters 10 and 11, but is not a prerequisite for those later chapters.

The Manchester Physics Series

General Editors

D. J. SANDIFORD: F. MANDL: A. C. PHILLIPS

Department of Physics and Astronomy, University of Manchester

Properties of Matter:

B. H. Flowers and E. Mendoza

Statistical Physics:

Second Edition

F. Mandl

Electromagnetism:

Second Edition

I. S. Grant and W. R. Phillips

Statistics:

R. J. Barlow

Solid State Physics:

Second Edition

J. R. Hook and H. E. Hall

Quantum Mechanics:

F. Mandl

Particle Physics:

Second Edition

B. R. Martin and G. Shaw

The Physics of Stars:

Second Edition

A. C. Phillips

Computing for Scientists:

R. J. Barlow and A. R. Barnett

Nuclear Physics:

J. S. Lilley

Copyright © 2001 by John Wiley & Sons Ltd,Baffins Lane, Chichester,West Sussex PO19 1UD, England

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British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 0 471 97935 X (cased) ISBN 0 471 97936 8 (paper)

Editors’ preface to the Manchester Physics Series

The Manchester Physics Series is a series of textbooks at first degree level. It grew out of our experience at the Department of Physics and Astronomy at Manchester University, widely shared elsewhere, that many textbooks contain much more material than can be accommodated in a typical undergraduate course; and that this material is only rarely so arranged as to allow the definition of a short self-contained course. In planning these books we have had two objectives. One was to produce short books: so that lecturers should find them attractive for undergraduate courses; so that students should not be frightened off by their encyclopaedic size or price. To achieve this, we have been very selective in the choice of topics, with the emphasis on the basic physics together with some instructive, stimulating and useful applications. Our second objective was to produce books which allow courses of different lengths and difficulty to be selected with emphasis on different applications. To achieve such flexibility we have encouraged authors to use flow diagrams showing the logical connections between different chapters and to put some topics in starred sections. These cover more advanced and alternative material which is not required for the understanding of latter parts of each volume.

Although these books were conceived as a series, each of them is self-contained and can be used independently of the others. Several of them are suitable for wider use in other sciences. Each Author’s Preface gives details about the level, prerequisites, etc., of that volume.

The Manchester Physics Series has been very successful with total sales of more than a quarter of a million copies. We are extremely grateful to the many students and colleagues, at Manchester and elsewhere, for helpful criticisms and stimulating comments. Our particular thanks go to the authors for all the work they have done, for the many new ideas they have contributed, and for discussing patiently, and often accepting, the suggestions of the editors.

Finally we would like to thank our publishers, John Wiley & Sons, Ltd, for their enthusiastic and continued commitment to the Manchester Physics Series.

D. J. SandifordF. MandlA. C. PhillipsFebruary 1997

Author’s preface

This book deals with the basic principles of nuclear physics and their many applications in the modern world. Much of the book is based on a course “Applications of Nuclear Physics”, which has been offered as a one-semester, third-year option in physics at the University of Manchester for a number of years.

The book is in two parts. Part I is a brief general introduction to the principles of nuclear physics. However, the emphasis of the book is on applications. These form Part II, which presupposes only a knowledge of the basic concepts developed in Chapter 1 of Part I. The aim of Part II is to introduce the reader to a wide diversity of applications and the underlying physics rather than to attempt a complete coverage of the subject.

The book is addressed mainly to science and engineering students, who require knowledge of the fundamental principles of nuclear physics and its applications. Some of these students may wish later to take advanced courses in nuclear physics or specialized courses in different areas of nuclear science and technology such as nuclear chemistry, nuclear engineering, instrumentation, radiation biology and nuclear medicine.

The level of the book is suitable for undergraduates in their second and third years of physics education and a corresponding grounding in introductory physics and mathematics is assumed.

The approach to the different topics is mainly from an experimental point of view, with illustrative examples. Complex and extensive mathematical treatments generally are avoided. However, where possible, an attempt is made to give a proper understanding based on fundamental physics principles. Derivations of formulae are given or outlined with a minimum of mathematical complexity. A bibliography contains references where much more extensive coverage can be found on all topics. Problem solving is an integral part of learning and understanding physics and, to that end, a set of problems is attached to each chapter. Hints and outlined solutions to all of them are collected together in an appendix.

The material in the book is designed to be used flexibly for a range of different courses. Part I could comprise a one-semester core course on the principles of nuclear physics, which introduces the main elements of nuclear structure, radioactivity and nuclear reactions. Part II can form the basis of different courses on applications allowing choice of topics and courses of different lengths. The flow diagram inside the front cover shows the logical connections between chapters and how material may be used selectively. In addition, much of the material in Part II can be tailored to meet specific needs. For example, if only the basic principles of a nuclear reactor are wanted, the sections in Chapter 10 dealing with the finite reactor, reactor operation and future uses may be omitted.

It is a pleasure to acknowledge the many friends and colleagues who have assisted me in the course of this work. These include Kevin Connell, John Hemingway, Tony Phillips, Roy Ryder, David Sandiford, Harbans Sharma and John Simpson. 1 am particularly grateful for the many thoughtful comments and helpful suggestions given to me by Bill Phillips and by Paddy Regan, who volunteered to read the entire manuscript.

Finally, I owe a special debt of gratitude to my editor Franz Mandl for his patient guidance throughout and for his critical comments and innumerable detailed suggestions, which contributed so much to the production and quality of the final manuscript.

February 2001J. S. Lilley

PART I

PRINCIPLES

1

Introduction and Basic Concepts

1.1 INTRODUCTION

It was in 1896 that Becquerel in France detected, by chance, faint traces of the existence of the nucleus in the atom. For many years after that the study of nuclear physics remained a curiosity and intellectual challenge to scientists, but had little practical use outside its own field. The situation changed totally in the 1930s with discoveries that culminated in the cataclysmic demonstrations near the end of the second world war of the immense energy locked up by the force that holds the atomic nucleus together. An unprecedented and irrevocable step had been taken in the degree of power available to humankind with dramatic consequences for good and ill.

Today, nuclear physics has entered into our modern world in a significant way. It influences other branches of science: chemistry, biology, archaeology, geology, engineering, astrophysics and cosmology. It is used widely in society at large – in industry, the environment, medicine, defence, criminology, power production and many other areas. Applications are found even in religion and the arts, where equipment and methods developed originally for nuclear research have found novel application. However, the exploitation of such a powerful force carries with it some danger and is the subject of much debate.

The main aim of this book is to address the broad range and variety of the techniques and applications of nuclear physics used today. The basic physics underlying them is given first in order that the benefits and drawbacks can be properly appreciated. No particular stance is taken on controversial issues. The view taken is that a proper understanding of the subject is important and necessary in order that wise decisions can be taken about how nuclear energy and nuclear radiation should be used.

Essential nuclear physics for understanding the applications is given in this first chapter. Other chapters in Part I give further development of the topics introduced in Chapter 1. The coverage of the applications in Part II is by no means exhaustive. It is intended broadly to inform the reader and provide a suitable preparation for those students who plan to take more advanced courses on any of the separate topics.

Unlike atomic physics, which is underpinned by electromagnetism, there is no fundamental theoretical formalism that completely describes nuclei and nuclear behaviour. For example, there is no formula, analogous to Coulomb’s law for the force between two electric charges, which exactly expresses the force between two basic constituents of the nucleus. Progress in understanding the nature of nuclei is made using approximate models, each of which provides insight into the complexity of the real situation, but with a limited range of applicability. Models are drawn from analogy with classical and other branches of physics and are formulated to be consistent with observed properties and behaviour. Conceptual models played a vital role in the first few decades of the twentieth century when the basic framework of the subject was being established. The following section is a short account of this early period.

1.2 EARLY DISCOVERIES

The history of the nucleus dates from the latter years of the nineteenth century with the observation by Becquerel in 1896 of the fogging of photographic plates by an unknown radiation emanating from uranium-bearing rocks. He had encountered radioactivity. Detailed studies of this new phenomenon began to be made, notably by Marie and Pierre Curie in France and by Ernest Rutherford, who had come to England from New Zealand earlier in 1895 to work in Cambridge with J. J. Thompson (who discovered the electron in 1897). It was soon revealed that there are three, distinctly different types of radiation emitted by radioactive substances. They were called alpha (α), beta (β) and gamma (γ) rays – terms which have been retained to this day.

The most far-reaching advances in the subject during this early phase were made by Rutherford. He and his co-workers, first in Canada (1898–1907) and later in Manchester, England (1907–1919), began an intensive study of the new radiations. All the laws governing radioactive decay were established. It was shown that α- and β-radioactive decays change the nature of the element and that a particles are helium nuclei. Beta particles were found to be the same as electrons, and γ rays were identified as energetic photons (electromagnetic radiation).

Rutherford used α particles to probe the structure of the atom itself. It was already known that the atom consisted of positively charged and negatively charged components, but there were two very different models for describing how these components might combine to form an atom. The ‘planetary9 model assumed that light, negatively charged electrons orbit a heavy, positively charged nucleus. The problem with this model was that the electrons would be constantly accelerating and should radiate energy as electromagnetic waves, causing the atom to collapse. In an alternative model, proposed by J. J. Thompson, the electrons are embedded and free to move in an extended region of positive charge filling the entire volume of the atom. Such an atom would not collapse, but Thompson had difficulty in developing his model. For example, he was never able to account successfully for the discrete wavelengths observed in the spectra of light emitted by excited atoms.

The crucial breakthrough came from experiments carried out by Rutherford and his team in Manchester, who were studying the passage of a particles through matter. It was noted that very thin foils of gold caused a particles to be deflected occasionally through large angles and even in the backward direction. Rutherford realized that this could not be due to the combined effect of a large number of small-angle deflections and could only be explained if the a particle had encountered a tiny, but heavy, charged entity less than 1/1000th of the atom in size. Undaunted by the fact that the planetary model should not exist according to classical theory, he proposed that the atom does consist of a small, heavy positively charged centre surrounded by orbiting electrons which occupy the vast bulk of the atom‘s volume. The simplest atom, hydrogen, consisted of a proton and a single orbital electron.