Advanced materials and techniques for radiation dosimetry

1 Introduction 1 References 8 2 Radiation Dosimetry: Background and Principles 11 2.1 Review of Radiation Types 11 2.1.1 Ionizing Radiation 11 2.1.2 Stopping Power and Linear Energy Transfer 14 2.1.3 Radiation Units 24 2.2 Biological Effects of Radiation 25 2.2.1 Types of Radiation Effects 25 2.2.2 Relative Biological Effectiveness 28 2.3 Basic Principles of Radiation Protection 31 2.4 Dosimetry for Industrial Radiation Processing 33 2.4.1 Medical Devices Sterilization 33 2.4.2 Food Irradiation 34 2.4.3 Modification of Polymers 35 2.5 Medical Use of Ionizing Radiation 37 2.5.1 In Vivo Dosimetry 38 vii 2.6 Uncontrolled Radioactive Releases 39 2.6.1 Nuclear Accidents 40 2.6.2 Radioecology After Nuclear Accidents 41 2.6.3 Further Examples of Nuclear Contamination 45 2.7 Review of the Principles and Materials in Radiation Dosimetry 46 2.7.1 Dosimetry 46 2.7.2 Classification and Calibration of Dosimeters 48 2.7.3 Gas-Filled Detectors 51 2.7.4 Scintillation Counters 57 2.7.5 Chemical Dosimeters 61 2.7.6 Radiochromic Dye Films 61 2.7.7 TLDs 62 2.7.8 Radiation Dosimetry Using MOS Devices 70 2.7.9 Interaction of Ionizing Radiation with Semiconductor Detectors 71 2.7.10 Response of Diodes to External Exposure 75 2.7.11 Other Radiation-Sensitive Materials of Interest 79 References 84 3 Effect of Radiation on Optical and Electrical Properties of Materials 91 3.1 Introduction 91 3.2 Optical Absorption 92 3.3 Amorphous Films 94 3.4 Absorption Spectra of Amorphous Solids 96 3.5 Metal-Semiconductor Contacts 99 3.5.1 Ohmic Contact 99 3.5.2 Neutral Contact 99 3.5.3 Blocking Contact 100 3.6 Conduction Mechanisms in Amorphous Materials 101 3.6.1 Schottky Versus Poole-Frenkel Conduction Mechanism 104 3.7 Radiation Damage in Crystalline Structures 105 3.8 Radiation-Induced Defects in Oxide Materials 106 3.9 Radiation Effects in Polymers 108 3.10 Radiation-Induced Degradation Processes in Device Parameters 112 References 113 4 Gamma Radiation Dosimetry Using Metal Oxides and Metal Phthalocyanines 115 4.1 Thin and Thick Film Technologies 115 4.1.1 Thin Film Technologies 115 4.1.2 Thick Film Technology 116 4.2 Thin Films as Radiation Sensors 117 4.2.1 Metal Oxides Thin Films 118 4.2.2 Metal-Substituted Phthalocyanines Thin Films 132 4.3 Thick Films as Radiation Sensors 137 4.3.1 Effects of γ-Rays on the Optical and Electrical Properties of Metal Oxide Thick Films 137 4.3.2 Effects of γ-Rays on the Optical Density of MePc Thick Films 145 4.3.3 MOS Dosimeter Using Bismuth Oxide (Bi2O3) and Copper Phthalocyanine (CuPc) Polymer Thick Films 150 4.4 Conclusion 153 References 154 5 Sensor Arrays, Radiation Nose Concept, and Pattern Recognition 159 5.1 Sensor Arrays 159 5.1.1 In2O3/SiO Sensor Array 159 5.1.2 PolyVinyliDene Fluoride Films of Different Thicknesses 161 5.1.3 Multiple Sensor Materials Incorporated into an Array 162 5.2 Dosimetry of Mixed Radiations 162 5.2.1 Electronic Nose Systems 163 5.3 Radiation Nose Concept: Overview of Pattern Recognition 165 5.3.1 Radiation Nose Concept 165 5.3.2 Overview of Pattern Recognition 168 5.3.3 Feature Extraction/Selection 171 5.4 Classification and Validation 172 5.4.1 Classification 172 5.4.2 Principal Component Analysis 172 5.4.3 Linear Discriminant Analysis 175 5.4.4 Validation 175 5.5 Radiation Nose Using a Compaq iPAQ Designed for Resistive Sensors 176 5.6 Portable Real-Time Gamma Radiation Dosimetry System Using MgO and CeO2 Thick Film Capacitors 179 5.6.1 Change of Capacitance with Dose 179 5.6.2 Circuit 180 5.6.3 Software 181 References 186 6 Conclusions and Future Trends 189 6.1 Necessity of Radiation Dosimetry 189 6.2 The Choice of Detector 189 6.3 Standards and Requirements 190 6.4 Future Trends 191 References 191 Acronyms 193 Appendix 199 About the Authors 201 Index 203