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Annihilation

Annihilation. Describe what happens in the process of annihilation Apply the law of the conservation of mass/energy. Starter: Can you write a nuclear equation to show annihilation?. Process of Annihilation. Positron annihilation. Annihilation gives 2 gamma rays 180 degrees apart

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Annihilation

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  1. Annihilation • Describe what happens in the process of annihilation • Apply the law of the conservation of mass/energy Starter: Can you write a nuclear equation to show annihilation?

  2. Process of Annihilation

  3. Positron annihilation • Annihilation gives • 2 gamma rays • 180 degrees apart • Position of source • Gamma rays are detected by PET scanner e+ e-

  4. Law of conservation of energy states that: Energy CANNOT be DESTROYED or CREATED, ONLY TRANSFERRED from one type into another. • Therefore total energy before and after collision must be the same.

  5. Calculating the Energy Produced • Mass of an electron = 9.11 x 10-31kg • E = mc2 Mass of electron and positron are the same. • Total energy at the start ( E = mc2) = 9.11 x 10-31 x (3 x 108)2 x 2 = 1.64 x 10-13J • So energy of gamma rays = 1.64 x 10-13J • As there are two gammas rays produced, each ray has an energy of 8.2 x 10-14J

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