Contents
1. Basic Nuclear Processes in Radioactive Sources ......................... 1
1.1 Nuclear Level Diagrams ........................................ 2
1.2 Alpha Decay .................................................. 3
1.3 Beta Decay ................................................... 4
1.4 Electron Capture (EC).......................................... 6
1.5 Gamma Emission.............................................. 6
1.5.1 Isomeric States........................................... 6
1.6 Annihilation Radiation ......................................... 7
1.7 Internal Conversion............................................ 7
1.8 Auger Electrons ............................................... 8
1.9 Neutron Sources............................................... 8
1.9.1 Spontaneous Fission ...................................... 8
1.9.2 Nuclear Reactions ........................................ 8
1.10 Source Activity Units........................................... 9
1.11 The Radioactive Decay Law ..................................... 10
1.11.1 Fluctuations in Radioactive Decay ......................... 11
1.11.2 Radioactive Decay Chains ................................ 12
1.11.3 Radioisotope Production by Irradiation..................... 14
2. Passage of Radiation Through Matter ................................. 17
2.1 Preliminary Notions and Definitions.............................. 17
2.1.1 The Cross Section ....................................... 18
2.1.2 Interaction Probability in a Distance x. Mean Free Path ....... 19
2.1.3 Surface Density Units .................................... 20
2.2 Energy Loss of Heavy Charged Particles by Atomic Collisions ........ 21
2.2.1 Bohr's Calculation - The Classical Case.................... 22
2.2.2 The Bethe-Bloch Formula................................ 24
2.2.3 Energy Dependence...................................... 27
2.2.4 Scaling Laws for dE/dx .................................. 28
2.2.5 Mass Stopping Power .................................... 28
2.2.6 dE/dx for Mixtures and Compounds ....................... 29
2.2.7 Limitations of the Bethe-Bloch Formula and Other Effects..... 29
2.2.8 Channeling............................................. 30
2.2.9 Range ................................................. 30
2.3 Cherenkov Radiation........................................... 33
2.4 Energy Loss of Electrons and Positrons ........................... 34
2.4.1 Collision Loss .......................................... 35
2.4.2 Energy Loss by Radiation: Bremsstrahlung.................. 35
2.4.3 Electron-Electron Bremsstrahlung ......................... 38
2.4.4 Critical Energy.......................................... 38
2.4.5 Radiation Length.......................................... 39
2.4.6 Range of Electrons ........................................ 40
2.4.7 The Absorption of β Electrons............................... 40
2.5 Multiple Coulomb Scattering ..................................... 40
2.5.1 Multiple Scattering in the Gaussian Approximation............. 43
2.5.2 Backscattering of Low-Energy Electrons ...................... 45
2.6 Energy Straggling: The Energy Loss Distribution .................... 46
2.6.1 Thick Absorbers: The Gaussian Limit ........................ 46
2.6.2 Very Thick Absorbers...................................... 47
2.6.3 Thin Absorbers: The Landau and Vavilov Theories ............. 47
2.7 The Interaction of Photons....................................... 50
2.7.1 Photoelectric Effect ....................................... 51
2.7.2 Compton Scattering ....................................... 52
2.7.3 Pair Production........................................... 54
2.7.4 Electron-Photon Showers................................... 56
2.7.5 The Total Absorption Coefficient and Photon Attenuation ...... 57
2.8 The Interaction of Neutrons ...................................... 58
2.8.1 Slowing Down of Neutrons. Moderation ..................,... 60
3. Radiation Protection. Biological Effects of Radiation.................... 65
3.1 Dosimetric Units ............................................... 65
3.1.1 The Roentgen............................................. 65
3.1.2 Absorbed Dose ........................................... 66
3.1.3 Relative Biological Effectiveness (RBE) ....................... 67
3.1.4 Dose Equivalent........................................... 68
3.2 Typical Doses from Common Sources in the Environment............. 68
3.3 Biological Effects............................................... 69
3.3.1 High Doses Received in a Short Time ......................... 70
3.3.2 Low-Level Doses .......................................... 70
3.4 Maximum Permissible Dose (MPD) ............................... 72
3.5 Shielding ...................................................... 72
3.6 Radiation Safety in the Nuclear Physics Laboratory.................. 73
4. Statistics and the Treatment of Experimental Data....................... 75
4.1 Characteristics of Probability Distributions......................... 75
4.1.1 Cumulative Distributions ................................... 76
4.1.2 Expectation Values ........................................ 76
4.1.3 Distribution Moments. The Mean and Variance ................ 76
4.1.4 The Covariance ........................................... 77
4.2 Some Common Probability Distributions........................... 78
4.2.1 The Binomial Distribution .................................. 78
4.2.2 The Poisson Distribution ................................... 79
4.2.3 The Gaussian or Normal Distribution......................... 80
4.2.4 The Chi-Square Distribution ................................ 82
4.3 Measurement Errors and the Measurement Process .................. 83
4.3.1 Systematic Errors ......................................... 83
4.3.2 Random Errors ........................................... 84
4.4 Sampling and Parameter
Estimation. The Maximum Likelihood Method 85
4.4.1 Sample Moments.......................................... 85
4.4.2 The Maximum Likelihood Method........................... 86
4.4.3 Estimator for the Poisson Distribution........................ 87
4.4.4 Estimators for the Gaussian Distribution...................... 88
4.4.5 The Weighted Mean ....................................... 90
4.5 Examples of Applications........................................ 91
4.5.1 Mean and Error from a Series of Measurements ................ 91
4.5.2 Combining Data with Different Errors........................ 91
4.5.3 Determination of Count Rates and Their Errors................ 92
4.5.4 Null Experiments. Setting
Confidence Limits When No Counts Are
Observed................................................. 92
4.5.5 Distribution of Time Intervals Between Counts................. 94
4.6 Propagation of Errors ........................................... 94
4.6.1 Examples ................................................ 95
4.7 Curve Fitting................................................... 96
4.7.1 The Least Squares Method.................................. 97
4.7.2 Linear Fits. The Straight Line ............................... 98
4.7.3 Linear Fits When Both Variables Have Errors.................. 101
4.7.4 Nonlinear Fits ............................................ 101
4.8 Some General Rules for Rounding-off Numbers for Final Presentation .. 105
5. General Characteristics of Detectors................................... 107
5.1 Sensitivity ..................................................... 107
5.2 Detector Response .............................................. 108
5.3 Energy Resolution. The Fano Factor............................... 109
5.4 The Response Function.......................................... 111
5.5 Response Time ................................................. 112
5.6 Detector Efficiency ............................................. 113
5.7 Dead Time..................................................... 114
5.7.1 Measuring Dead Time...................................... 116
6. Ionization Detectors ................................................ 119
6.1 Gaseous Ionization Detectors..................................... 119
6.2 Ionization and Transport Phenomena in Gases ...................... 122
6.2.1 Ionization Mechanisms..................................... 122
6.2.2 Mean Number of Electron-Ion Pairs Created .................. 123
6.2.3 Recombination and Electron Attachment ..................... 124
6.3 Transport of Electrons and Ions in Gases ........................... 125
6.3.1 Diffusion ................................................ 125
6.3.2 Drift and Mobility......................................... 126
6.4 Avalanche Multiplication ........................................ 127
6.5 The Cylindrical Proportional Counter ............................. 129
6.5.1 Pulse Formation and Shape ................................. 129
6.5.2 Choice of Fill Gas ......................................... 132
6.6 The Multiwire Proportional Chamber (MWPC) ..................... 133
6.6.1 Basic Operating Principle................................... 133
6.6.2 Construction ............................................. 135
6.6.3 Chamber Gas ............................................. 136
6.6.4 Timing Resolution......................................... 136
6.6.5 Readout Methods ......................................... 137
6.6.6 Track Clusters ........................................... 139
6.6.7 MWPC Efficiency........................................ 139
6.7 The Drift Chamber ............................................ 141
6.7.1 Drift Gases .............................................. 142
6.7.2 Spatial Resolution ........................................ 143
6.7.3 Operation in Magnetic Fields............................... 143
6.8 The Time Projection Chamber (TPC) ............................. 143
6.9 Liquid Ionization Detectors ..................................... 146
7. Scintillation Detectors............................................... 149
7.1 General Characteristics ......................................... 149
7.2 Organic Scintillators ........................................... 151
7.2.1 Organic Crystals ......................................... 154
7.2.2 Organic Liquids.......................................... 155
7.2.3 Plastics ................................................. 156
7.3 Inorganic Crystals ............................................. 157
7.4 Gaseous Scintillators ........................................... 158
7.5 Glasses....................................................... 159
7.6 Light Output Response ......................................... 159
7.6.1 Linearity................................................ 160
7.6.2 Temperature Dependence.................................. 163
7.6.3 Pulse Shape Discrimination (PSD) .......................... 163
7.7 Intrinsic Detection Efficiency for Various Radiations................ 165
7.7.1 Heavy Ions .............................................. 165
7.7.2 Electrons................................................ 166
7.7.3 Gamma Rays ............................................ 166
7.7.4 Neutrons................................................ 167
8. Photomultipliers ................................................... 169
8.1 Basic Construction and Operation................................ 169
8.2 The Photocathode ............................................. 170
8.3 The Electron-Optical Input System ............................... 172
8.4 The Electron-Multiplier Section.................................. 173
8.4.1 Dynode Configurations ................................... 174
8.4.2 Multiplier Response: The Single-Electron Spectrum............ 176
8.5 Operating Parameters .......................................... 177
8.5.1 Gain and Voltage Supply .................................. 177
8.5.2 Voltage Dividers ......................................... 178
8.5.3 Electrode Current. Linearity ............................... 180
8.5.4 Pulse Shape ............................................. 181
8.6 Time Response and Resolution................................... 182
8.7 Noise ........................................................ 184
8.7.1 Dark Current and Afterpulsing ............................. 184
8.7.2 Statistical Noise .......................................... 185
8.8 Environmental Factors ......................................... 186
8.8.1 Exposure to Ambient Light ................................ 186
8.8.2 Magnetic Fields .......................................... 187
8.8.3 Temperature Effects ...................................... 188
8.9 Gain Stability, Count Rate Shift ................................. 189
9. Scintillation Detector Mounting and Operation ......................... 191
9.1 Light Collection .............................................. 191
9.1.1 Reflection............................................. 192
9.2 Coupling to the PM ........................................... 193
9.3 Multiple Photomultipliers...................................... 194
9.4 Light Guides ................................................. 194
9.5 Fluorescent Radiation Converters ............................... 196
9.6 Mounting a Scintillation Detector: An Example ................... 197
9.7 Scintillation Counter Operation................................. 200
9.7.1 Testing the Counter..................................... 200
9.7.2 Adjusting the PM Voltage ............................... 201
9.7.3 The Scintillation Counter Plateau......................... 201
9.7.4 Maintaining PM Gain................................... 205
10. Semiconductor Detectors ........................................... 207
10.1 Basic Semiconductor Properties................................. 207
10.1.1 Energy Band Structure .................................. 208
10.1.2 Charge Carriers in Semiconductors........................ 209
10.1.3 Intrinsic Charge Carrier Concentration .................... 209
10.1.4 Mobility .............................................. 210
10.1.5 Recombination and Trapping ............................ 211
10.2 Doped Semiconductors ........................................ 212
10.2.1 Compensation ......................................... 214
10.3 The np Semiconductor Junction. Depletion Depth ................. 215
10.3.1 The Depletion Depth.................................... 216
10.3.2 Junction Capacitance ................................... 218
10.3.3 Reversed Bias Junctions ................................. 218
10.4 Detector Characteristics of Semiconductors....................... 219
10.4.1 Average Energy per Electron-Hole Pair .................... 220
10.4.2 Linearity.............................................. 221
10.4.3 The Fano Factor and Intrinsic Energy Resolution............ 221
10.4.4 Leakage Current ....................................... 221
10.4.5 Sensitivity and Intrinsic Efficiency ........................ 222
10.4.6 Pulse Shape. Rise Time.................................. 223
10.5 Silicon Diode Detectors........................................ 225
10.5.1 Diffused Junction Diodes................................ 225
10.5.2 Surface Barrier Detectors (SSB)........................... 225
10.5.3 Ion-Implanted Diodes................................... 226
10.5.4 Lithium-Drifted Silicon Diodes - Si(Li) ................... 227
10.6 Position-Sensitive Detectors.................................... 227
10.6.1 Continuous and Discrete Detectors........................ 227
10.6.2 Micro-Strip Detectors................................... 229
10.6.3 Novel Position-Sensing Detectors ......................... 230
10.7 Germanium Detectors ......................................... 231
10.7.1 Lithium-Drifted Germanium - Ge(Li) .................... 231
10.7.2 Intrinsic Germanium.................................... 232
10.7.3 Gamma Spectroscopy with Germanium Detectors ........... 233
10.8 Other Semiconductor Materials ................................. 234
10.9 Operation of Semiconductor Detectors........................... 235
10.9.1 Bias Voltage .......................................... 235
10.9.2 Signal Amplification................................... 235
10.9.3 Temperature Effects ................................... 237
10.9.4 Radiation Damage..................................... 237
10.9.5 Plasma Effects........................................ 238
11. Pulse Signals in Nuclear Electronics .................................. 241
11.1 Pulse Signal Terminology ..................................... 241
11.2 Analog and Digital Signals .................................... 242
11.3 Fast and Slow Signals ........................................ 244
11.4 The Frequency Domain. Bandwidth ............................ 245
12. The NIM Standard ................................................ 249
12.1 Modules.................................................... 249
12.2 Power Bins ................................................. 250
12.3 NIM Logic Signals ........................................... 250
12.4 TTL and ECL Logic Signals ................................... 253
12.5 Analog Signals .............................................. 253
13. Signal Transmission ................................................ 255
13.1 Coaxial Cables .............................................. 255
13.1.1 Line Constituents ..................................... 257
13.2 The General Wave Equation for a Coaxial Line................... 258
13.3 The Ideal Lossless Cable ...................................... 259
13.3.1 Characteristic Impedance............................... 260
13.4 Reflections ................................................. 260
13.5 Cable Termination. Impedance Matching........................ 262
13.6 Losses in Coaxial Cables. Pulse Distortion....................... 264
13.6.1 Cable Response. Pulse Distortion ........................ 267
14. Electronics for Pulse Signal Processing ............................... 269
14.1 Preamplifiers ............................................... 269
14.1.1 Resistive vs Optical Feedback ........................... 271
14.2 Main Amplifiers............................................. 272
14.3 Pulse Shaping Networks in Amplifiers .......................... 272
14.3.1 CR-RC Pulse Shaping.................................. 273
14.3.2 Pole-Zero Cancellation and Baseline Restoration........... 273
14.3.3 Double Differentiation or CR-RC-CR Shaping............. 274
14.3.4 Semi-Gaussian Shaping ................................ 275
14.3.5 Delay Line Shaping .................................... 275
14.4 Biased Amplifiers............................................ 276
14.5 Pulse Stretchers ............................................. 276
14.6 Linear Transmission Gate..................................... 276
14.7 Fan-out and Fan-in .......................................... 277
14.8 Delay Lines ................................................. 278
14.9 Discriminators .............................................. 278
14.9.1 Shapers .............................................. 279
14.10 Single-Channel Analyzer (Differential Discriminator) ............. 279
14.11 Analog-to-Digital Converters (ADC or A/D)..................... 281
14.11.1 ADC Linearity....................................... 283
14.12 Multichannel Analyzers....................................... 283
14.13 Digital-to-Analog Converters (DAC or D/A)..................... 284
14.14 Time to Amplitude Converters (TAC or TPHC) .................. 286
14.15 Scalers ..................................................... 286
14.16 Ratemeter .................................................. 286
14.17 Coincidence Units ........................................... 287
14.18 Majority Logic Units......................................... 287
14.19 Flip-Flops .................................................. 288
14.20 Registers (Latches) ........................................... 289
14.21 Gate and Delay Generators .................................... 289
14.22 Some Simple and Handy Circuits for Pulse Manipulation .......... 289
14.22.1 Attenuators ......................................... 290
14.22.2 Pulse Splitting ....................................... 290
14.22.3 Pulse Inversion ...................................... 291
14.23 Filtering and Shaping......................................... 291
14.23.1 Pulse Clipping ....................................... 291
14.23.2 High-Pass Filter or CR Differentiating Circuit ............ 292
14.23.3 RC Low-Pass Filter or Integrating Circuit ................ 293
15. Pulse Height Selection and Coincidence Technique ..................... 295
15.1 A Simple Counting System .................................... 295
15.2 Pulse Height Selection........................................ 296
15.2.1 SCA Calibration and Energy Spectrum Measurement ...... 297
15.2.2 A Note on Calibration Sources ......................... 298
15.3 Pulse Height Spectroscopy with Multichannel Analyzers ........... 299
15.4 Basic Coincidence Technique .................................. 302
15.4.1 Adjusting the Delays. The Coincidence Curve............. 303
15.4.2 Adjusting Delays with the Oscilloscope .................. 304
15.4.3 Accidental Coincidences............................... 305
15.5 Combining Pulse Height Selection and Coincidence Determination.
The Fast-Slow Circuit ........................................ 305
15.6 Pulse Shape Discrimination ................................... 306
16. Electronic Logic for Experiments .................................... 309
16.1 Basic Logic Gates: Symbols................................... 309
16.2 Boolean Laws and Identities................................... 311
16.3 The Inhibit or Busy .......................................... 313
16.4 Triggers .................................................... 313
16.4.1 One-Body Scattering.................................. 314
16.4.2 Two-Body Scattering ................................. 314
16.4.3 Measurement of the Muon Lifetime ..................... 315
17. Timing Methods and Systems ....................................... 317
17.1 Walk and Jitter.............................................. 317
17.2 Time-Pickoff Methods ....................................... 318
17.2.1 Leading Edge Triggering (LE) .......................... 318
17.2.2 Fast Zero-Crossing Triggering.......................... 319
17.2.3 Constant Fraction Triggering (CFT)....................... 319
17.2.4 Amplitude and Risetime Compensated Triggering (ARC) ..... 319
17.3 Analog Timing Methods ....................................... 320
17.3.1 The START-STOP Time-to-Amplitude Converter........... 321
17.3.2 Time Overlap TAC's.................................... 321
17.4 Digital Timing Methods ....................................... 322
17.4.1 The Time-to-Digital Converter (TDC) ..................... 322
17.4.2 The Vernier TDC....................................... 323
17.4.3 Calibrating the Timing System............................ 325
18. Computer Controlled Electronics: CAMAC ........................... 327
18.1 CAMAC Systems............................................. 328
18.2 The CAMAC Standard ........................................ 330
18.2.1 Mechanical Standards................................... 330
18.2.2 Electrical Standards: Digital Signals....................... 330
18.3 The CAMAC Dataway ........................................ 330
18.3.1 Common Control Signals (Z, C, I) ........................ 333
18.3.2 Status Signals .......................................... 333
18.3.3 Timing Signals ......................................... 333
18.3.4 Data Signals ........................................... 333
18.3.5 Address Signals ........................................ 333
18.3.6 Command Signals ...................................... 334
18.3.7 Pin Allocations ........................................ 334
18.4 Dataway Operations .......................................... 335
18.4.1 Dataway Timing ....................................... 336
18.4.2 Block Transfers ........................................ 338
18.5 Multi-Crate Systems - The Branch Highway ..................... 340
18.6 CAMAC Software ............................................ 341
Appendix ............................................................ 345
A. A Review of Oscilloscope Functions .................................. 345
A.l Basic Structure ............................................... 345
A.l.1 Bandwidth and Risetime................................. 345
A.2 Controls and Operating Modes ................................. 346
A.2.1 Input Coupling ........................................ 346
A.2.2 Vertical and Horizontal Sensitivity ........................ 346
A.2.3 Triggering (Synchronization) ............................. 347
A.2.4 Display Modes ......................................... 347
A.3 Applications and Examples..................................... 348
A.3.1 Signal Viewing ......................................... 348
A.3.2 Comparison of Signals .................................. 348
B. Physical and Numerical Constants ................................... 349
C. Resistor Color Code ............................................... 350
References ........................................................... 351
Subject Index......................................................... 361
Preface369
Contents..371