Plastic Scintillators: Chemistry and Applications

Description

This book introduces the physics and chemistry of plastic scintillators (fluorescent polymers) that are able to emit light when exposed to ionizing radiation, discussing their chemical modification in the early 1950s and 1960s, as well as the renewed upsurge in interest in the 21st century. The book presents contributions from various researchers on broad aspects of plastic scintillators, from physics, chemistry, materials science and applications, covering topics such as the chemical nature of the polymer and/or the fluorophores, modification of the photophysical properties (decay time, emission wavelength) and loading of additives to make the material more sensitive to, e.g., fast neutrons, thermal neutrons or gamma rays. It also describes the benefits of recent technological advances for plastic scintillators, such as nanomaterials and quantum dots, which allow features that were previously not achievable with regular organic molecules or organometallics. Foreword References Preface Contents Contributors Part I Materials 1 Introduction—Overview on Plastic and Inorganic Scintillators 1.1 History of Scintillators 1.2 Plastic Scintillator Chemists 1.3 The Scintillation Process in Plastics and Inorganic Materials/Crystals 1.4 Typical Preparation Process and Size Possibilities 1.5 Main Parameters and Tools for Modification or Improvement 1.5.1 Light Yield 1.5.2 Decay Time 1.5.3 Emission Wavelength 1.5.4 Behavior Against External Environment 1.5.5 Effective Atomic Number and Density 1.6 Summary References 2 Neutron/Gamma Pulse Shape Discrimination in Plastics Scintillators: From Development to Commercialization 2.1 Physical Basis for Neutron/Gamma Discrimination in Organic Scintillators 2.2 Plastic Scintillators with Efficient Fast Neutron/Gamma Discrimination 2.2.1 PPO-Based PSD Plastics 2.2.2 PSD Plastics Utilizing Alternative Dyes and Dye Mixtures 2.3 PSD Plastics for Combined Detection of Fast and Thermal Neutrons 2.3.1 10B-loaded PSD Plastic Scintillators 2.3.2 6Li-loaded PSD Plastic Scintillators 2.4 Commercialization and Further Directions of Studies References 3 The Detection of Slow Neutrons 3.1 Slow Neutrons: Essential Features 3.1.1 The Definition of Slow Neutrons 3.1.2 The Origins of Slow Neutrons 3.2 Nuclear Reactions of Interest in Slow Neutron Detection 3.2.1 Natural Abundance, Reaction Cross Section, Q-Value, and Typology of Reaction Products 3.2.2 Main Nuclear Reactions of Interest 3.2.3 Size of the Scintillator: Slow Neutron Mean Free Path and the Interaction of Reaction Products 3.3 Detection of Reaction Products and n/γ Discrimination 3.3.1 Background Radiation 3.3.2 Pulse Height Discrimination 3.3.3 Pulse Shape Discrimination 3.3.4 Compensated Detectors 3.3.5 Multiplicity-Gated Detection 3.3.6 Capture-Gated Detection 3.4 Figures of Merit for Slow Neutron Detectors 3.4.1 Figures of Merit About the Response to Neutrons 3.4.2 Figures of Merit About the Response to Gamma Rays 3.4.3 Figures of Merit About the Response to Neutron Against the Response to Gamma Rays 3.5 Incorporation of Neutron Converters into Plastic Scintillator-Based Detectors 3.5.1 Homogeneous Incorporation 3.5.2 Heterogeneous Incorporation 3.6 Applications of Plastic Scintillators to the Detection of Slow Neutrons 3.6.1 Homeland Security 3.6.2 Neutron Flux Monitoring and Source Characterization 3.6.3 Reactor Antineutrino Experiments, Surveillance, and Monitoring References 4 Chemical Approach on Organometallic Loading in Plastic Scintillators and Its Applications 4.1 Introduction/Context 4.1.1 Plastic Scintillation 4.1.2 Frame of This Chapter 4.1.3 Properties Optimization 4.1.4 Chemical Design and Material Science, What the Loading Implies 4.1.5 Organization of This Chapter: Application Driven 4.2 Scintillation Process Enhancement 4.2.1 Triplet Harvesting 4.2.2 Iridium Complexes 4.2.3 Europium Complexes 4.3 Photon Detection 4.3.1 Theory 4.3.2 X-ray Detection 4.3.3 Gamma Detection 4.4 Neutron Detection 4.4.1 Thermal Neutron 4.4.2 Lithium Loading 4.4.3 Boron Loading 4.4.4 Cadmium and Gadolinium Loading 4.5 Conclusion 4.6 Table by Elements References 5 Polysiloxane-Based Scintillators 5.1 Foreword 5.1.1 Silicon-Based Polymer Properties: Chemistry 5.1.2 The Synthesis of Silicones 5.2 Optical Properties of Phenyl-Containing Polysiloxanes 5.3 Design of Polysiloxane-Based Scintillators 5.3.1 Energy Transfer in Organic Polymers 5.3.2 Polymeric Scintillators 5.3.3 Polysiloxane-Based Scintillators 5.4 Polysiloxane Scintillators for Neutron Detection 5.4.1 Neutron Detection in Organic Scintillators 5.4.2 B and Li Loaded Polysiloxanes for Detection of Thermal Neutrons 5.4.3 Design of Polysiloxane Scintillators for n/γ Discrimination 5.5 Summary References 6 Composite Scintillators 6.1 Introduction to Organic–Inorganic Composites 6.1.1 Overview on Fabrication Methods of Nanocomposites 6.1.2 Optical Properties Related to the Nanocomposite Structure 6.2 Plastic Scintillators Incorporating Non-emitting Inorganic Nanoparticles 6.2.1 Sol–gel-Derived Organic–Inorganic Composite Scintillators 6.2.2 Nanocomposite Scintillators Fabricated via Two-Step Synthesis 6.3 Nanocomposite Scintillators Comprising Luminescent Nanoparticles 6.3.1 Nanocomposite Scintillators Comprising Inorganic Phosphor Nanoparticles 6.3.2 Nanocomposite Scintillators Comprising Semiconductor Nanocrystals 6.4 Summary and Future Prospects References 7 Molecular Design Considerations for Different Classes of Organic Scintillators 7.1 Design Considerations for Crystalline, Plastic, and Liquid Scintillators 7.1.1 Background on Scintillation Mechanisms 7.1.2 Process (1): Direct Excitation into π-Electronic States 7.1.3 Process (2): Overview of Direct Ionization and Recombination of π-states 7.1.4 Physical and Mechanical Properties of Different Classes of Organic Scintillators 7.2 Future Opportunities References 8 Organic Glass Scintillators 8.1 Introduction to Organic Glass Scintillators 8.2 Glassy State of Matter 8.3 Differentiating Characteristics of Organic Molecular Glasses 8.4 Design Strategies for Stable Organic Molecular Glasses 8.4.1 Nonplanar Structures 8.4.2 Increasing Molecular Size 8.4.3 Multiple Conformations 8.4.4 Physical Mixtures 8.5 Fluorescent Molecular Glasses as Organic Glass Scintillators (OGSs) 8.6 Organic Glass Scintillators: Case Studies 8.7 Organic Glass Thermal and Mechanical Properties 8.7.1 Mechanical Strength: Intermolecular Interactions 8.7.2 Mechanical Strength: Organic Glass/Polymer Blending 8.8 Properties of OGS/Polymer Blends 8.8.1 Effect of Small-Molecule Additives on Tg 8.8.2 Scintillation Properties of OGS/Polymer Blends 8.9 Organic Glass Scintillator Fabrication Methods 8.10 Long-Term Stability and Environmental Aging of Organic Glass Scintillators 8.10.1 Surface Versus Bulk Diffusion 8.10.2 Accelerated Aging of Organic Glasses and Mitigation Methods 8.11 Compatibility of OGS with Multi-functional Additives 8.11.1 Boron-Loaded OGS for Fast Neutron/Gamma PSD and Thermal Neutron Capture 8.11.2 Metal-Loaded OGS for Fast Neutron/Gamma PSD and Gamma-Ray Spectroscopy 8.12 Summary and Future Outlook References Part II Applications 9 Optical Improvements of Plastic Scintillators by Nanophotonics 9.1 Introduction 9.2 Enhancement of Light Extraction Efficiency of Plastic Scintillators by Photonic Crystals 9.2.1 Introduction of Photonic Crystals 9.2.2 Enhancement Mechanism of Light Extraction Efficiency by Photonic Crystals 9.2.3 Control of Directional Emission by Photonic Crystals 9.2.4 Consideration for the Structural Design of Photonic Crystals 9.3 Control of Directional Emission of Plastic Scintillators by Plasmonic Lattice Resonances 9.4 Patterning Techniques for Plastic Scintillators 9.4.1 Self-assembly Lithography 9.4.2 Nanoimprint Lithography (NIL) 9.4.3 X-Ray Interference Lithography (XIL) 9.5 Improved Scintillation Performance of Detectors by Photonic Crystals 9.6 Summary and Remark References 10 Analog and Digital Signal Processing for Nuclear Instrumentation 10.1 Introduction 10.2 The Light to Electric Signal Conversion 10.2.1 Design of PMTs 10.2.2 Solid-State Semiconductor Photodetectors 10.3 The Signal Acquisition Frontend 10.3.1 Charge to Voltage Conversion 10.3.2 Gain and Pulse Shaping Stage 10.3.3 Voltage Limiters 10.3.4 Impedance Matching and Other Effects 10.4 The Digitization Stage 10.4.1 Signal Digitization Basics 10.4.2 Digitizer Architectures 10.5 Signal Processing and Feature Extraction 10.5.1 Low-Level Digital Stream Processing 10.5.2 Digital Pulse Processing 10.6 Data and Information Processing 10.6.1 Count Rate Analysis 10.6.2 Discrimination of the Nature of the Interactions 10.6.3 Spectral Unmixing and Radionuclide Identification 10.7 Conclusion References 11 Radioactive Noble Gas Detection and Measurement with Plastic Scintillators 11.1 Radioactive Noble Gas Isotopes 11.1.1 Kr-85 11.1.2 Xe-131m 11.1.3 Xe-133 11.1.4 Xe-133m 11.1.5 Xe-135 11.1.6 Ar-37 11.1.7 Rn-222 and Progenies 11.1.8 Rn-220 and Progenies 11.2 Application of Plastic Scintillators to the Detection of Noble Gas 11.2.1 Xenon Detection Systems for the CTBT Network 11.2.2 Kr-85 Monitors Using Plastic Scintillators 11.2.3 Radon and Thoron Detection and Measurement with Plastic Scintillators 11.3 RNG-Related Properties of Plastic Scintillators 11.3.1 Noble Gas Absorption in Plastic Materials 11.3.2 Application of Pulse Shape Discrimination to 222Rn Measurements 11.3.3 Description of the Alpha-Particle Peak Shapes in 222Rn Measurements with Plastic Scintillators 11.4 Concluding Remarks References 12 Recent Advances and Clinical Applications of Plastic Scintillators in the Field of Radiation Therapy 12.1 Introduction 12.2 Basic Dosimetry Properties of Plastic Scintillators 12.2.1 Basic Properties of Scintillators Used in Radiation Therapy 12.2.2 Relating Scintillation Signal to Absorbed Dose 12.2.3 Other Properties 12.3 Signal Processing in Plastic Scintillators Dosimeters 12.3.1 Cherenkov and Other Sources of Stem Effects 12.3.2 Multi-point Radiation Therapy Plastic Scintillator Dosimeters 12.4 Clinical Applications and Special Procedures 12.4.1 Photon and Electron External Beam Radiation Therapy 12.4.2 Proton External Beam Radiation Therapy 12.4.3 Brachytherapy 12.5 Conclusion References 13 Plastic Scintillators in Environmental Analysis 13.1 Environmental Analysis: Requirements and Characteristics. Contribution of Plastic Scintillators 13.2 Preparation of Plastic Scintillators for Environmental α/β Emitting Radionuclide Analysis 13.2.1 Fibers and Sheets 13.2.2 Plastic Scintillation Particles 13.2.3 Stability of Plastic Scintillation Microspheres 13.2.4 Plastic Scintillation Resins 13.3 Direct Surface and Soil Analysis 13.4 Sensors and Online Analysis of Alpha and Beta Emitting Radionuclides 13.4.1 Sensors Based on Plastic Scintillation Microspheres (PSm) 13.4.2 Sensors Based on Plastic Scintillation Resins 13.4.3 Sensors Based on Plastic Scintillation Fibers (PSf) 13.4.4 Sensors Based on Plastic Scintillation Sheets 13.5 Plastic Scintillators for Beta Emitting Radionuclide Analysis 13.6 Plastic Scintillators for Alpha Emitting Radionuclide Analysis 13.7 Conclusion References 14 Use of Scintillators to Study the Earth from Ground to the Radiation Belts 14.1 Survey of Earth Natural Radioactivity and Potential Nuclear Accidents, Citizen Science 14.1.1 Source of Terrestrial Natural Radioactivity 14.1.2 Sources of Radioactive Pollution in the Environment 14.1.3 Nuclear Activities Survey and Alert in Case of Accident: Description of Official and NGO Networks 14.1.4 Measuring and Mapping the Radioactivity in the Environment: The Citizen Science Approach 14.2 High-Energy Processes in the Atmosphere, Terrestrial Gamma-Ray Flashes (TGFs), and Gamma-Ray Glows 14.2.1 Gamma Ray Emissions During Thunderstorms 14.2.2 Gamma-Ray Glows 14.2.3 Terrestrial Gamma-Ray Flashes (TGFs) 14.2.4 TARANIS: A Satellite to Study the Effects of Thunderstorms and Lightning 14.2.5 Measure of Gamma Rays and Particles in the Earth Radiation Belts 14.2.6 Measure of Gamma Rays/Particles from the Radiation Belts 14.2.7 IGOSAT: A Student Nanosat Project to Measure Radiation Belts Gamma Ray/Particles 14.3 Conclusion References 15 Plastic Scintillator Detectors for Particle Physics 15.1 Introduction 15.2 Principles of Calorimetry in High-Energy Physics 15.2.1 Electromagnetic and Hadronic Showers 15.2.2 Historical Review of Plastic Scintillating Calorimetry 15.3 Modern Plastic Scintillator Calorimeter Design 15.3.1 Experiments at the Large Hadron Collider 15.3.2 High-Granularity Calorimeters for Particle Flow Strategies 15.3.3 Dual-Readout Solutions 15.4 Neutrino Experiments 15.4.1 Optimizing Calorimeters for Neutrino Physics 15.4.2 Tracking Calorimeters for Neutrinos 15.5 Large Plastic Scintillator Detectors in the Future 15.5.1 Neutron Sensitivity 15.6 Conclusion References Appendix Molecules Cited in the Book Index