652 



ISOTOPIC TRACERS AND NUCLEAR RADIATIONS 



Scaling circuits, for counters, 329-333 

 Scattering, anomalous, 93 



of beta particles, 61-63, 365, 373 



of charged particles, 92-93 



elastic, 123-126, 154-155, 317 



of gamma rays, 32, 36-39 



inelastic, 127-129 



of neutrons, 123-129 



by hydrogenous substances, 124 



resonance, 93, 125-126 



rutherford, 92-93 

 Scattering cross section of hydrogen for 



neutrons, 318 

 Scattering potential, 125-126 

 Screening constant, 82 

 Secondary electron emission, 341 

 Secondary electrons, 41-42 

 Secondary ionization, 55 

 Secondary radiation by gamma rays, 41- 



42 

 Self-absorption, 377-378 

 Sensitive volume, of counters, 373 



of ionization chambers, 346-347, 361 

 Sensitivity, of isotopic tracers, 389 



of radioautograph emulsions, 385-386 

 Shielding materials for gamma rays, 461- 



463 

 Shielding of radioactive substances, 454- 



456, 461-463, 468-471 

 Silicon, in biological tracer studies, 529, 547 



isotopes of, 15, 190-191 

 Silver, in biological tracer studies, 533, 548 



isotopes of, 18, 217-218 

 Slow neutron interaction, 126-127 

 Sodium, in biological tracer studies, 520- 

 521, 542, 545 



isotopes of, 15, 189-190 



in radiotherapy, 540, 550 

 Spallation, 186 

 Specific activity, of labeled substances, 393 



of radioactive tracers, 391 

 Specific ionization, 54 



of alpha particles, 89, 360 



of charged particles, 89-90 

 Spin, 11, 163-164 



of isotopes, 22-27 



of nuclei, 11-13 

 Sputtering, 292 



Stability of nuclei, 11, 150-151 

 Standard deviation, 314-321, 355-357 



Standardization by the coincidence method, 



362-364 

 Starting voltage, 309 

 Statistical errors, 363 

 Statistical fluctuations, 363 

 Statistics, of counters, 318-321 



of counting rate meters, 339 



of ionization chambers, 355-357 



of nuclei, 163-164 

 Sticking probability for neutrons, 128 

 Stokes' law, 272, 274 

 Stopping cross section, 85, 108 

 Stopping formula, 51, 53, 77-86, 155 



of Bethe, 77-83 



corrections in, 80-81 



for electrons, 51-54 



of Fermi, 53, 83-85 



for heavy charged particles, 77-85 

 Stopping power, 51, 349, 407-408 



atomic, 85 



for fission fragments, 156 



mass, 86 



relative, 55, 85 



of various substances, 85-86 

 Storage of radioactive substances, 454 

 Straggling, 53 



of charged particles, 90-92 



of fission fragments, 154 

 Stripping film, 382-386 

 Strontium, in biological tracer studies, 531- 

 532, 543, 547 



isotopes of, 17, 208-209 



in radiotherapy, 541, 550 

 Structural materials in radiochemistry 



laboratories, 454r-455 

 Sulfur, in biological tracer studies, 518, 

 542, 547 



isotopes of, 15, 191, 518 

 Surface energy, 8, 10 

 Surface tension of nucleus, 148-150 

 Synchro-cyclotron, 130 

 Synchrotron, 493-499 



construction of, 493-496 



synchronous orbits in, 498 



Targets, 91-92, 130 



Thermal neutron (See Neutrons) 



Thermal noise, 294 



