Introduction to Nuclear Radiation Detectors

200 Pages·1975·6.372 MB·English

by  P. J. Ouseph (auth.)

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Introduction to
Nuclear Radiation
Detectors
PJOuseph
Department of Physics
College of Arts and Sciences
University of Louisville
Louisville, Kentucky
PLENUM PRESS • NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
Ouseph, P J 1933·
Introduction to nuclear radiation detectors.
(Laboratory instrumentation and techniques ; v. 2)
Bibliography: p.
Includes index.
1. Nuclear counters. I. Title.
QC787.C6088 539.7'7 75·15744
ISBN-13: 978-1-4684-0837-9 e-ISBN-13: 978-1-4684·0835·5
DOl: 10.1007/978·1-4684-0835-5
@1975 Plenum Press, New York
Softcover reprint of the hardcover 18t edition 1975
A Division of Plenum Publishing Corporation
227 West 17th Street New York N.Y. 10011
United Kingdom edition published by Plenum Press, London
A Division of Plenum Publishing Company, Ltd.
Davis House (4th Floor), 8 Scrubs Lane, Harlesden, London NWI0 6SE, England
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted,
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
To
Ann, Rosemary,
John, and Maryann
Preface
There have been many interesting developments in the field of
nuclear radiation detectors, especially in those using semiconduct
ing materials. The purpose of this book is to present a survey of
the developments in semiconductor detectors along with discus
sions about gas counters and scintillation counters. These discus
sions are directed to detector users, usually scientists and
technicians in different fields such as chemistry, geology, bio
chemistry, and medicine. The operation of these detectors is
discussed in terms of basic properties, such as efficiency, energy
resolution, and resolving time, which are defmed in the first
chapter. Differences among these detectors in terms of these
properties are pointed out. Chapter 2, on interaction of radiations
with matter, discusses how different radiations lose energies in
matter and how differences in their behavior in matter affect the
design and operation of detectors. Although emphasis is placed on
fundamentals throughout the book, the reader is also made aware
quite often of the new developments in the field of radiation
detection.
The author has taught a course in radioisotopes for several
years for science, engineering, medical, and dental students. The
emphasis on topics varied from time to time to satisfy the varying
interests of the students. However, the contents of this book
formed the core of the course. About ten selected experiments on
detectors were done along with this course (a list of these
vii
viii Preface
experiments may be supplied on request). The enthusiastic
response received from the students encouraged the writing of
this book.
The help I received from several individuals during the
preparation of this book deserves special mention. Professor
Manual Schwartz initiated and developed the course on radioiso
topes and radiation detection at our university. As mentioned
earlier, this book originated with this course, modified through
years of teaching. Without his help in reading, correcting and
modifying the manuscript, especially in its early stages, this book
would not have been possible. I am deeply indebted to Professor
Schwartz for this help and for his collaboration in writing two
articles on detectors which gave me additional impetus in writing
this book.
I should also acknowledge the help I received from Thomas
Lanigan and Ralph Cutler of the editorial staff of Plenum Press. I
am especially grateful to Dr. Galen Ewing, the editor of this
series, for his patient efforts in correcting and editing this book.
In preparing the diagrams, the help I received from Mrs.
Catherine M. Bauscher deserves special recognition. Nor should
I forget the assistance provided by Miss Lisa Hark in the typing
of this manuscript. Finally, my appreciation goes to my family for
their patience and encouragement.
Louisville, Kentucky P. J. OUSEPH
May, 1975
Contents
Chapter 1
INTRODUCTION 1
Chapter 2
NUCLEAR RADIATIONS AND THEIR INTERACTION
WITH MATTER _________________ ~------------------- 7
2.1. Radioactivity __________________________________ 8
2.2. Radioactivity Calculations ______________________ 10
2.3. Calculation of Activities Produced by Nuclear
Reactions ____________________________________ 15
2.4. Interaction of Heavy Charged Particles with Matter 20
2.5. Electron Interaction ____________________________ 29
2.6. Backscattering of Electrons ____________________ 34
2.7. Interaction of Gamma and X Rays with Matter 37
2.8. Interaction of Neutrons ________________________ 44
2.9. Cosmic Rays __________________________________ 46
References ____________________________________ 46
Bibliography __________________________________ 46
Chapter 3
GAS COUNTERS ______________________________________ 47
3.1. General Properties of Gas Counters ______________ 47
ix
x Contents
3.2. Ionization Counters ____________________________ 52
3.3. Air-Wall Ionization Chamber ____________________ 52
3.4. Pocket Dosimeter ______________________________ 53
3.5. Pulse-Type Ionization Counter __________________ 54
3.6. Proportional Counter __________________________ 60
3.7. Position-Sensitive Proportional Counters ________ 66
3.8. Neutron Counters ____________________________ 67
3.9. Geiger-Miiller Counters ________________________ 68
3.10. Counter Gas __________________________________ 74
3.11. Detection of Alpha and Beta Radiations by
Geiger Counters ______________________________ 76
3.12. Detection of X Rays and Gamma Rays by
Gas Counters ________________________________ 77
3.13. Application of Internal Counting Methods ________ 79
References ____________________________________ 81
Bibliography __________________________________ 82
Chapter 4
SCINTILLATION COUNTERS .. _____ • __ .. _. .._ ____ 83
~-----__
4.1. General Characteristics of Scintillation
Counting Systems .. _______________ .________ 83
4.2. Scintillant Materials and Mechanism of Scintillation 85
4.3. Photomultipliers .. ____________________________ 95
4.4. The Shape of the Pulse _________ .. _____ .. ________ 100
4.5. Scintillation Counter Assembly __________________ 101
4.6. Relationship between Pulse Height and Energy 102
4.7. Detection of Gamma Rays by Scintillation
Counters ______________________________________ 104
4.8. Integral Counting ______________________________ 109
4.9. Differential Counting and Determination of
Energy of Gamma Rays ________________________ 111
4.10. Efficiency of Scintillation Counters for
Gamma Detection ____________________________ 115
4.11. Energy Resolution in Scintillant Detectors ________ 117
Contents xi
4.12. Detection of Charged Particles with
Scintillation Counters ___________________________ 120
4.13. Detection of Neutrons __________________________ 121
4.14. Particle Identification by Pulse Shape
Discrimination _________________________________ 123
4.15. Other Methods for Particle Identification and
Discrimination ________________________________ 124
References ____________________________________ 127
Bibliography __________________________________ 127
Chapter 5
SEMICONDUCTOR DETECTORS 129
5.1. Operation of a Semiconductor Counter __________ 129
5.2. Impurity Semiconductors ______________________ 133
5.3. Detector Types ________________________________ 140
5.4. Pulse Shape and Rise Time ____________________ 148
5.5. Factors Affecting Energy Resolution ____________ 149
5.6. Radiation Damage ____________________________ 152
5.7. Detection of Charged Particles __________________ 153
5.8. X-Ray and Gamma-Ray Detection ______________ 158
5.9. Neutron Detectors ____________________________ 161
5.10. Other Applications ____________________________ 161
5.11. Special Techniques ____________________________ 164
5.12. Concluding Remarks __________________________ 166
References __________________________________ 167
Bibliography ________________________________ 167
Chapter 6
CORRECTIONS IN RADIATION COUNTING 169
6.1. Introduction __________________________________ 169
6.2. Absolute Activity Determination ________________ 178
6.3. Random Nature of Decay Process ______________ 180
6.4. Frequency Distributions ________________________ 181
6.5. Statistical Errors in Nuclear Particle Counting ____ 185
References ____________________________________ 187
Bibliography __________________________________ 187