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Pair Production.

 Pair Production.

  • The formation of an electron and positron(positively charge electron) from a photon, usually in the vacinity of an atomic nucleus is called pair production.
    Pair production
    Pair production.
  • In this process electromagnetic energy is changed into matter.                𝜸⁰⟶ e⁺ + e⁻
  • The inverse of pair production (pair annihilation) occurs when a positron is near an electron and the two come together under the influence of their opposite electric charges.                                               e⁺+ e⁻ ⟶ 𝜸 + 𝜸
  • No nucleus or other particle is needed for pair annihilation to take place.
  • In pair production any law of conservation is not violated. The sum of the charges of the electron (q=-e) and of the positron (q=+e) is zero, as is the charge of photon; the total energy, including rest energy, of the electron and positron equals the photon energy and linear momentum is also conserved. Thus during pair production law of conservation of energy, linear momentum and electric charge are followed.
  • Pair production cannot occur in free space as the law of conservation of momentum and energy are not followed there.
  • The rest energy of an electron or positron is 0.51 MeV, hence pair production requires a photon energy of atleast 1.02 MeV. Any additional photon energy becomes kinetic energy of the electron and positron.
Fill in the blanks:
1) The formation of an electron and positron(positively charge electron) from a photon, usually in the vacinity of an atomic nucleus is called ------------.
2)In this process electromagnetic energy is changed into ------.                                          3)𝜸⁰⟶ e⁺ + ---.
4)The inverse of pair production is called -----.
5)e⁺+ e⁻ ⟶ 𝜸 + ---.
3)In pair production any law of conservation is ---- violated. 
6)The sum of the charges of the electron (q=-e) and of the positron (q=+e) is -------, as is the charge of photon.
7)The total energy, including rest energy, of the electron and positron ------ the photon energy and linear momentum is also conserved.
8)Pair production cannot occur in ---------- as the law of conservation of momentum and energy are not followed there.
9)The rest energy of an electron or positron is ----- MeV.
10 )Pair production requires a photon energy of atleast ------ MeV. 
Ans)1) The formation of an electron and positron(positively charge electron) from a photon, usually in the vacinity of an atomic nucleus is called Pair production.
2)In this process electromagnetic energy is changed into matter.                                          3)𝜸⁰⟶ e⁺ + e⁻.
4)The inverse of pair production is called Pair Annihilation.
5)e⁺+ e⁻ ⟶ 𝜸 +  𝜸.
3)In pair production any law of conservation is not violated. 
6)The sum of the charges of the electron (q=-e) and of the positron (q=+e) is zero, as is the charge of photon.
7)The total energy, including rest energy, of the electron and positron equals the photon energy and linear momentum is also conserved.
8)Pair production cannot occur in free space as the law of conservation of momentum and energy are not followed there.
9)The rest energy of an electron or positron is 0.51 MeV.
10 )Pair production requires a photon energy of atleast 1.02 MeV. 

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