Radioistope Experiments for Schools and Colleges (eBook)

Front Cover 1
Radioisotope Experiments for Schools and Colleges 4
Copyright Page 5
Table of Contents 6
Preface 10
Acknowledgements 13
CHAPTER 1. Fundamentals 14
The Discovery of Radioactivity 14
Atomic Structure 15
Types of Radioactive Change 17
Decay Kinetics 20
The Interaction of Radiation with Matter 23
Bremsstrahlung 25
Gamma Radiation 26
Isotope Production 28
CHAPTER 2. The Measurement of Nuclear Radiation 29
Geiger Counte 29
Scintillation Detectors 37
Semiconductor Detectors 38
Scalers 38
Resolving Time 40
Background Counts 42
Ratemeters 43
Absolute and Relative Counting 44
Absorption Measurements 45
Self-absorption 49
The Pocket Dosimeter 60
The Quartz Fibre Ionisation Chamber 60
The Pulse Electroscope 63
CHAPTER 3. Naturally Occurring Radioisotopes 64
Natural Radioactive Series 64
Branching Chains 71
Uranium Compounds 71
Thorium 73
The Emanations 73
Other Natural Radioisotopes 75
CHAPTER 4. Health Physics 76
Radiation and Contamination 76
Dose Units 77
Maximum Permissible Doses 79
Dose Rate Calculations 80
Beta and Gamma Dose Rates 84
Precautions in the Use of Closed Sources 85
Measurement of Gamma Dose Rate 85
Contamination 86
Precautions in the Use of Unsealed Isotopes 87
Monitoring 88
Maximum Permissible Levels 89
Film Badge Service 90
CHAPTER 5. Some Practical Considerations 91
Sources 91
Purchasing Unsealed Isotopes 92
Geiger Counting Equipment 94
Types of Detector 96
Photographic Techniques 100
Half-life Experiments 100
Half-life Graphs 101
Half-life from a Growth Curve 103
Carriers 105
Solvent Extraction 106
Ion Exchange 107
Electro-deposition 107
Preparation of Solid Samples 108
CHAPTER 6.Some Demonstration Experiments 110
Experiment 6.1. Becquerel's Discovery 110
Experiment 6.2. Distinction between Alpha, Beta and Gamma Radiation 112
Experiment 6.3. Deflection of Beta Particles in a Magnetic Field 114
Experiment 6.4. Backscatter 115
Experiment 6.5. Activity of Potassium Salts 115
Experiment 6.6. Cloud Chambers 116
Experiment 6.7. Relative Ionising Power of Alpha, Beta and Gamma Radiat 117
Experiment 6.8. Scintillations 120
Experiment 6.9. Dose Rate Measurements 121
Experiment 6.10. The Spark Counter 121
Experiment 6.11. Half-life Experiments 121
Experiment 6.12. Alpha Particle Range 124
Experiment 6.13. Bremsstrahlung Production 125
CHAPTER 7. Experiments Using Naturally Occurring Radioisotopes 128
Experiment 7.1. The Characteristics of a Geiger Tube 128
Experiment 7.2. Geiger Pulse Amplitude and Duration 131
Experiment 7.3. The Statistics of Counting 132
Experiment 7.4. Determination as to whether a Solid is Radioactive 133
Experiment 7.5. External Beta Absorption Curves 134
Experiment 7.6. Self-absorption in a Beta Emitter 136
Experiment 7.7. Self-absorption in a Solution 137
Experiment 7.8. The Separation of 234mPa by Solvent Extraction 138
Experiment 7.9. The Separation of 234mPa by Precipitation with Zirconium Phosphate 143
Experiment 7.10. The Preparation of 234mPa and 234Th by the Use of an Ion Exchange Column 144
Experiment 7.11. The Preparation of 234Th by Precipitation 145
Experiment 7.12. The Half-life of Thoron using an Ionisation Chamber 147
Experiment 7.13. The Determination of the Half-life of Thoron using a G.M. Tube 149
Experiment 7.14. Measurement of Gas Flow Rate using Thoron Decay 150
Experiment 7.15. The Preparation of 212Pb from Thorium Hydroxide by Electrostatic Deposition 152
Experiment 7.16. The Preparation of 212Bi by Electrostatic Deposition 156
Experiment 7.17. The Preparation of 212Pb and 212Bi by Solvent Extraction 158
Experiment 7.18. Backscatter 158
Experiment 7.19. The Preparation of 208TI by Liquid Extraction 159
Experiment 7.20. The Preparation of 208TI by Precipitation 160
Experiment 7.21. The Separation of 208TI by Adsorption 161
Experiment 7.22. The Use of 212Pb as a Tracer 162
Experiment 7.23. The Determination of the Surface Area of a Precipitate 163
Experiment 7.24. The Determination of Small Concentrations of Uranium or Thorium by means of Nuclear Emulsions 165
Experiment 7.25. Estimation of the Branching Ratio of ThC using a Nuclear Emulsion 166
Experiment 7.26. The Determination of Long Half-lives 166
Experiment 7.27. Alpha Particle Ranges in a Nuclear Emulsion 169
Experiment 7.28. The Estimation of the Half-life of 40K 170
Experiment 7.29. The Separation of ThX (224Ra) with MsTh 1 (228Ra) 172
Experiment 7.30. The Concentration of Airborne Radioisotopes 173
CHAPTER 8. Experiments Using Sealed Sources 176
Experiment 8.1. The Inverse Square Law Experiment for Gamma Radiation 176
Experiment 8.2. The Absorption of Gamma Radiation 178
Experiment 8.3. The Decrease of Beta Flux with Source Distance 178
Experiment 8.4. The Determination of the Resolving Time of Geiger Counting Equipment 179
Experiment 8.5. Simple Gamma Radiography 181
CHAPTER 9. Experiments Using Unsealed Artificially Produced Isotopes 182
Experiment 9.1. The Structure of the Thiosulphate Ion 182
Experiment 9.2. The Dynamic Equilibrium between a Metal and its Ions 184
Experiment 9.3. Coprecipitation and Adsorption 185
Experiment 9.4. The Preparation of a Labelled Compound 186
Experiment 9.5. The Absorption of Phosphorus by a Plant 187
Experiment 9.6. The Absorption of Phosphorus by Yeast 188
Problems 189
APPENDIX 1: Regulations on the Use of Radioisotopes in United Kingdom Educational Establishments 191
The Radioactive Substances Act, 1960 192
Exemptions 193
Levels of Work 195
Approval by the Secretary of State 196
Schools Level 197
Transport of Radioisotopes 201
APPENDIX 2: Radioisotope Data 202
APPENDIX 3: Table of Resolving Time Corrections for a Dead Time of 400 Microseconds 208
APPENDIX 4: List of Manufacturers 212
References 215
Index 218