(3) This amplification continues through A multiplication factor 10 to 14 stages, the last dynode is of over 1 million is reached. possible. (4) At the anode, a current pulse is formed and sent to the circuits. 7. Other components of a scintillation system are: a. Linear amplifier provides additional – amplification for the pulse and shapes the pulse. b. Pulse height analyzer correlates pulse – height to radiation energy. c. Readout device accepts pulses whose – heights fall within a given range from the upper and lower level discriminators. 8. Scintillation Outputs a. Efficiency is nearly 100% for alpha or beta that enters the detector. Efficiency is much less for gamma. This makes energy b. The advantage to using solid scintillation differentiation and crystals for gamma counting is that the nuclide identification output pulse is directly proportional to the possible. energy of the incident gamma. 9. In addition to sodium iodide, zinc sulfide and organic scintillators are used. a. Sodium Iodide (Thallium Activated), NaI(Th) used for gamma counting – because of its density. b. Silver Activated Zinc Sulfide, ZnS(Ag) – has a powdered coating on a transparent material, such as mylar, and is used for alpha counting. c. Organic scintillators, both liquid and solid, are used for beta counting. 10. The advantages of scintillation detectors include: Objective B.9 a. high sensitivity. b. high efficiency for gamma detection. c. capacity to handle high counting rates. Objective B.9 d. can detect different types and energies. e. can measure the energy spectrum in emitters. 11. The disadvantages of scintillation detectors include: a. detector crystal can be ruined by moisture. b. expensive and fragile. c. poor low energy gamma response. d. can be affected by temperature. e. must have a highly regulated power supply.
(3) This amplification continues through 10 to 14 stages, the last dynode is reached. (4) At the anode, a current pulse is formed and sent to the circuits. A multiplication factor of over 1 million is possible. 7. Other components of a scintillation system are: a. Linear amplifier – provides additional amplification for the pulse and shapes the pulse. b. Pulse height analyzer – correlates pulse height to radiation energy. c. Readout device – accepts pulses whose heights fall within a given range from the upper and lower level discriminators. 8. Scintillation Outputs a. Efficiency is nearly 100% for alpha or beta that enters the detector. Efficiency is much less for gamma. b. The advantage to using solid scintillation crystals for gamma counting is that the output pulse is directly proportional to the energy of the incident gamma. This makes energy differentiation and nuclide identification possible. 9. In addition to sodium iodide, zinc sulfide and organic scintillators are used. a. Sodium Iodide (Thallium Activated), NaI(Th) – used for gamma counting because of its density. b. Silver Activated Zinc Sulfide, ZnS(Ag) – has a powdered coating on a transparent material, such as mylar, and is used for alpha counting. c. Organic scintillators, both liquid and solid, are used for beta counting. 10. The advantages of scintillation detectors include: a. high sensitivity. b. high efficiency for gamma detection. Objective B.9 c. capacity to handle high counting rates. d. can detect different types and energies. e. can measure the energy spectrum in emitters. Objective B.9 11. The disadvantages of scintillation detectors include: a. detector crystal can be ruined by moisture. b. expensive and fragile. c. poor low energy gamma response. d. can be affected by temperature. e. must have a highly regulated power supply.
RadMeasurementInstrumentLessonPlan.docx