Physics and Engineering of Radiation Detection - Faculty

789 Pages·2008·5.99 MB·English

by  Syed Naeem Ahmed

Physics and Engineering
of Radiation Detection
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Physics and Engineering
of Radiation Detection
Syed Naeem Ahmed
Queen’s University, Kingston, Ontario
AMSTERDAM • BOSTON • HEIDELBERG • LONDON
NEW YORK • OXFORD • PARIS • SAN DIEGO
SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Academic Press is an imprint of Elsevier
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First edition 2007
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ISBN–13:978-0-12-045581-2
ISBN–10:0-12-045581-1
Dedicated to:
my parents whose loving memories still guide me through difficult times; my
wife, Rahat, without whose utmost love, support, and encouragements it
would not have been possible to write this book; and to my children Hiba,
Shozab, and Shanib, who have taught me things about life I could never have
learned myself.
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Contents
Preface xxiii
1 Properties and Sources of Radiation 1
1.1 Types of Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Waves or Particles? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Radioactivity and Radioactive Decay . . . . . . . . . . . . . . . . . 4
1.3.A Decay Energy or Q-Value . . . . . . . . . . . . . . . . . . . . 9
1.3.B The Decay Equation . . . . . . . . . . . . . . . . . . . . . . . 11
1.3.C Composite Radionuclides . . . . . . . . . . . . . . . . . . . . 15
1.3.D Radioactive Chain . . . . . . . . . . . . . . . . . . . . . . . . 18
1.3.E Decay Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . 22
E.1 Secular Equilibrium . . . . . . . . . . . . . . . . . . . . . . 22
E.2 Transient Equilibrium . . . . . . . . . . . . . . . . . . . . . 24
E.3 No Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.3.F Branching Ratio . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.3.G Units of Radioactivity . . . . . . . . . . . . . . . . . . . . . . 25
1.4 Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1.5 Sources of Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.5.A Natural Sources. . . . . . . . . . . . . . . . . . . . . . . . . . 27
A.1 Cosmic Radiation Sources . . . . . . . . . . . . . . . . . . . 27
A.2 Terrestrial Radiation Sources . . . . . . . . . . . . . . . . . 28
A.3 Internal Radiation Sources . . . . . . . . . . . . . . . . . . 28
1.5.B Man-Made Sources . . . . . . . . . . . . . . . . . . . . . . . . 29
1.6 General Properties and Sources of Particles and Waves . . . . . . . . 30
1.6.A Photons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
A.1 Sources of Photons . . . . . . . . . . . . . . . . . . . . . . . 32
1.6.B Electrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
B.1 Sources of Electrons . . . . . . . . . . . . . . . . . . . . . . 42
1.6.C Positrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
C.1 Sources of Positrons . . . . . . . . . . . . . . . . . . . . . . 45
1.6.D Protons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
D.1 Sources of Protons . . . . . . . . . . . . . . . . . . . . . . . 47
1.6.E Neutrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
E.1 Sources of Neutrons . . . . . . . . . . . . . . . . . . . . . . 49
1.6.F Alpha Particles . . . . . . . . . . . . . . . . . . . . . . . . . . 53
F.1 Sources of α-Particles . . . . . . . . . . . . . . . . . . . . . 54
1.6.G Fission Fragments . . . . . . . . . . . . . . . . . . . . . . . . 54
vii
1.6.H Muons, Neutrinos and other Particles . . . . . . . . . . . . . 56
H.1 Muons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
H.2 Neutrinos . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
H.3 Some Other Particles . . . . . . . . . . . . . . . . . . . . . 57
2 Interaction of Radiation with Matter 65
2.1 Some Basic Concepts and Terminologies . . . . . . . . . . . . . . . . 65
2.1.A Inverse Square Law . . . . . . . . . . . . . . . . . . . . . . . . 66
2.1.B Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.1.C Mean Free Path . . . . . . . . . . . . . . . . . . . . . . . . . 68
2.1.D Radiation Length . . . . . . . . . . . . . . . . . . . . . . . . . 70
2.1.E Conservation Laws . . . . . . . . . . . . . . . . . . . . . . . . 74
E.1 Conservation of Energy . . . . . . . . . . . . . . . . . . . . 75
E.2 Conservation of Momentum . . . . . . . . . . . . . . . . . . 75
E.3 Conservation of Electrical Charge. . . . . . . . . . . . . . . 76
2.2 Types of Particle Interactions . . . . . . . . . . . . . . . . . . . . . . 76
2.2.A Elastic Scattering . . . . . . . . . . . . . . . . . . . . . . . . . 77
2.2.B Inelastic Scattering . . . . . . . . . . . . . . . . . . . . . . . . 77
2.2.C Annihilation . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
2.2.D Bremsstrahlung . . . . . . . . . . . . . . . . . . . . . . . . . . 79
2.2.E Cherenkov Radiation . . . . . . . . . . . . . . . . . . . . . . . 80
2.3 Interaction of Photons with Matter . . . . . . . . . . . . . . . . . . . 82
2.3.A Interaction Mechanisms . . . . . . . . . . . . . . . . . . . . . 82
A.1 Photoelectric Effect . . . . . . . . . . . . . . . . . . . . . . 83
A.2 Compton Scattering . . . . . . . . . . . . . . . . . . . . . . 87
A.3 Thompson Scattering . . . . . . . . . . . . . . . . . . . . . 94
A.4 Rayleigh Scattering . . . . . . . . . . . . . . . . . . . . . . 94
A.5 Pair Production . . . . . . . . . . . . . . . . . . . . . . . . 95
2.3.B Passage of Photons through Matter . . . . . . . . . . . . . . 97
B.1 Measuring Attenuation Coefficient . . . . . . . . . . . . . . 101
B.2 Mixtures and Compounds . . . . . . . . . . . . . . . . . . . 102
B.3 Stacked Materials . . . . . . . . . . . . . . . . . . . . . . . 103
2.4 Interaction of Heavy Charged Particles with Matter . . . . . . . . . 105
2.4.A Rutherford Scattering . . . . . . . . . . . . . . . . . . . . . . 105
2.4.B Passage of Charged Particles through Matter . . . . . . . . . 110
2.4.C Bragg Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
2.4.D Energy Straggling . . . . . . . . . . . . . . . . . . . . . . . . 117
2.4.E Range and Range Straggling . . . . . . . . . . . . . . . . . . 118
E.1 Range of α-Particles . . . . . . . . . . . . . . . . . . . . . . 119
E.2 Range of Protons . . . . . . . . . . . . . . . . . . . . . . . . 121
2.5 Interaction of Electrons with Matter . . . . . . . . . . . . . . . . . . 122
2.5.A Interaction Modes . . . . . . . . . . . . . . . . . . . . . . . . 122
A.1 Ionization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
A.2 Moeller Scattering . . . . . . . . . . . . . . . . . . . . . . . 123
A.3 Bhabha Scattering . . . . . . . . . . . . . . . . . . . . . . . 123
A.4 Electron-Positron Annihilation . . . . . . . . . . . . . . . . 124
A.5 Bremsstrahlung . . . . . . . . . . . . . . . . . . . . . . . . . 124
A.6 Cherenkov Radiation . . . . . . . . . . . . . . . . . . . . . . 125
viii
2.5.B Passage of Electrons through Matter . . . . . . . . . . . . . . 127
2.5.C Energy Straggling . . . . . . . . . . . . . . . . . . . . . . . . 130
2.5.D Range of Electrons . . . . . . . . . . . . . . . . . . . . . . . . 132
2.6 Interaction of Neutral Particles with Matter . . . . . . . . . . . . . . 137
2.6.A Neutrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
A.1 Elastic Scattering. . . . . . . . . . . . . . . . . . . . . . . . 138
A.2 Inelastic Scattering . . . . . . . . . . . . . . . . . . . . . . . 138
A.3 Transmutation . . . . . . . . . . . . . . . . . . . . . . . . . 139
A.4 Radiative Capture . . . . . . . . . . . . . . . . . . . . . . . 139
A.5 Spallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
A.6 Fission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
A.7 Total Cross Section . . . . . . . . . . . . . . . . . . . . . . 140
A.8 Passage of Neutrons through Matter . . . . . . . . . . . . . 140
2.7 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
3 Gas Filled Detectors 149
3.1 Production of Electron-Ion Pairs . . . . . . . . . . . . . . . . . . . . 149
3.2 Diffusion and Drift of Charges in Gases . . . . . . . . . . . . . . . . 152
3.2.A Diffusion in the Absence of Electric Field . . . . . . . . . . . 152
A.1 Diffusion in the Presence of Electric Field . . . . . . . . . . 153
3.2.B Drift of Charges in Electric Field . . . . . . . . . . . . . . . . 153
B.1 Drift of Ions. . . . . . . . . . . . . . . . . . . . . . . . . . . 153
B.2 Drift of Electrons . . . . . . . . . . . . . . . . . . . . . . . . 155
3.2.C Effects of Impurities on Charge Transport . . . . . . . . . . . 157
3.3 Regions of Operation of Gas Filled Detectors . . . . . . . . . . . . . 161
3.3.A Recombination Region . . . . . . . . . . . . . . . . . . . . . . 161
3.3.B Ion Chamber Region . . . . . . . . . . . . . . . . . . . . . . . 161
3.3.C Proportional Region . . . . . . . . . . . . . . . . . . . . . . . 162
C.1 Avalanche Multiplication . . . . . . . . . . . . . . . . . . . 163
3.3.D Region of Limited Proportionality . . . . . . . . . . . . . . . 166
3.3.E Geiger-Mueller Region . . . . . . . . . . . . . . . . . . . . . . 166
E.1 Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
3.3.F Continuous Discharge . . . . . . . . . . . . . . . . . . . . . . 169
3.4 Ionization Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
3.4.A Current Voltage Characteristics . . . . . . . . . . . . . . . . . 170
3.4.B Mechanical Design . . . . . . . . . . . . . . . . . . . . . . . . 170
B.1 Parallel Plate Geometry . . . . . . . . . . . . . . . . . . . . 170
B.2 Cylindrical Geometry . . . . . . . . . . . . . . . . . . . . . 174
3.4.C Choice of Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
3.4.D Special Types of Ion Chambers . . . . . . . . . . . . . . . . . 178
D.1 Parallel Plate Frisch Grid Chamber . . . . . . . . . . . . . 178
D.2 Boron-lined Ion Chamber . . . . . . . . . . . . . . . . . . . 179
D.3 Compensated Ion Chamber . . . . . . . . . . . . . . . . . . 180
3.4.E Applications of Ion Chambers . . . . . . . . . . . . . . . . . . 181
3.4.F Advantages and Disadvantages of Ion Chambers . . . . . . . 181
3.5 Proportional Counters . . . . . . . . . . . . . . . . . . . . . . . . . . 182
3.5.A Multiplication Factor . . . . . . . . . . . . . . . . . . . . . . . 184
3.5.B Choice of Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
ix