Gamma ray spectrum by using na i(tl)detector ..
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The document discusses the study of gamma-ray spectrum using scintillation detectors and single channel analyzers, highlighting the nature of radioactive decay and transmutation. It explains different types of decay, including gamma decay, and delves into interactions of gamma radiation with matter, such as the photoelectric effect and Compton scattering. Additionally, it describes the properties and functioning of scintillation detectors, particularly thallium-activated sodium iodide (NaI(Tl)).
Gamma ray spectrum by using na i(tl)detector ..
- 1. Study of Gamma-ray Spectrum by using Scintillation detector and Single channel Analyzer
- 2. Radioactive decays Radioactive decay is the spontaneous breakdown of an atomic nucleus resulting in the release of energy and matter from the nucleus. We know that a radioisotope has unstable nuclei that does not have enough binding energy to hold the nucleus together. radioisotope would like to be stable isotopes so they are try to be stabilize. In the process, they will release energy and matter from their nucleus and often transform into a new element. This process, called transmutation, is the change of one element into another as a result of changes within the nucleus. The radioactive decay and transmutation process will continue until a new element is formed that has a stable nucleus and is not radioactive.
- 3. Types of Decay Alpha Decay Beta Decay - +1 + -1 Electron Capture. Gamma Decay Gamma decay occurs because the nucleus is at too high energy state. The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma particle. Flash Flash 1
- 4. What is gamma ray? Gamma radiation is one of the three types of natural radioactivity. Gamma rays are electromagnetic radiation. Gamma rays are the most energetic form of electromagnetic radiation, with a very short wavelength between 0.003 nm - 0.03 nm. They are produced by sub-atomic particle interactions such as electron-positron annihilation, radioactive decay.
- 5. Radioactive source (Na-22) Sodium-22 is the radioactive source which has 11 protons And 11 neutrons and by beta plus it is decay to Neon-22. In general of stable nuclei
- 6. Decay scheme in general
- 7. Na-22 Decay scheme Sodium 11 /10% 3.7 ps 90% Neon 22Na 22Ne + γ + β+ + υe
- 8. Interaction of gamma radiation with matter Photoelectric effect When a gamma-ray collides with an orbital electron of an atom of the material through which it is passing it can transfer all its energy to the electron and cease to exist. On the basis of the Principle of Conservation of Energy we can deduce that the electron will leave the atom with a kinetic energy equal to the energy of the gamma-ray, This electron is called a photoelectron.
- 9. Compton effect gamma-ray transfers only part of its energy to a valance electron which is essentially free. Notice that the electron leaves the atom and the gamma-ray deflects off in a different direction to that with which it approached the atom. This deflected or scattered gamma-ray can undergo further Compton Effects within the material. this effect is sometimes called Compton Scattering.
- 10. Pair production The incident Gamma Ray photon will interact with mater through pair production if its energy is greater than 1.02 Mev , in this process positron and electron will produced then the positron annihilate the two photons of 0.511 Mev produced of opposite direction.
- 11. Scintillation detector Is a detector which consist of a material which produce a flashes of light when absorb a radiation. These materials are variously called fluorescent materials, Scintillator .(we use Thallium activated sodium iodide)Nai(TL). Properties of Scintillators High scintillation efficiency. The conversion of radiation into light should be linear over a wide range of energies. The medium should be transparent to the scintillation light. The decay time of the produced scintillation light should be short. The index of refraction of the scintillator should be suitable.
- 12. Parts of scintillation detector Anode PMT Scintillator Multi-channel analyzer Nai(Tl) Radioactive Amplifier source Dynodes Photocathode
- 13. Nai(Tl) spectrum for Na-22 Electron positron annihilation peak at 0.511 Mev X-ray Compton edge Photopeak 1275 Kev
- 14. Thanks for Attention Prepared by Fourth stage –physics Department -2010-2011