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Physics and Engineering of Radiation Detection - Faculty

789 Pages · 2008 · 5.99 MB · English

  • Physics and Engineering of Radiation Detection - Faculty

    Physics and Engineering


    of Radiation Detection This page intentionally left blank 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 Academic Press is an imprint of Elsevier


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    First edition 2007


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    Printed and bound in Great Britain


    07 08 09 10 10 9 8 7 6 5 4 3 2 1


    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. This page intentionally left blank 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


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