Skip to main content

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. 

Comments

Post a Comment

Popular posts from this blog

LS coupling and jj coupling.

 Total angular momentum: The total angular momentum of an electron is the sum of the orbital angular momentum and spin angular momentum of the electron i.e Coupling Scheme Since an atom consist of large number of electrons having different orbital and spin momenta, Coupling scheme is necessary to obtain the resultant orbit and spin momenta of atom as a whole. There are two types of coupling scheme namely 1) LS Coupling 2) JJ Coupling. 1)LS Coupling: In this coupling the 'l' vectors of all electrons combine to form resultant 'L' vector and all the 's' vectors of these electrons combine to form resultant 'S' vector. Then the 'L' vector and 'S' vector undergoes vector addition to give resultant 'J' vector which represents the total angular momentum of an atom. Symbolically LS coupling is represented as This type of coupling is governed by the following principles: 1) All the three vectors (L,S and J vectors) are quantized. 2)L is an ...
Post a Comment
Read more

Different kinds of beta decay.

 Different kinds of beta decay 1) Negative beta decay process: When there is excess number of neutrons in the nucleus, the neutron is converted into proton with the emission of electron and antineutrino particle and this process is called negative beta decay process. Negative beta decay. 2) Positive beta decay process: When there is excess number of protons in the nucleus, the proton is converted into neutron with the emission of positron and neutrino particle and this process is called positive beta decay process. Positive beta decay. 3) Electron Capture: When there is excess number of protons in the nucleus, sometimes the nucleus will absorbed the nearby electrons in the nearest electron orbital emitting neutron and a neutrino and this process is called electron capture. Electron capture. 4) Inverse beta decay: Inverse beta decay. Thus such kind of reaction in which neutrinos are absorbed to create some sort of beta decay is called inverse beta decay. Inverse beta decay confirm t...
Post a Comment
Read more

Photoelectric effect.

 Photoelectric effect; The emission of electrons by a substance under the action of light is called Photoelectric effect. Photoelectric Effect. Experimental Setup: The phenomenon of photoelectric effect can be studied with the help of an apparatus shown in Figure below. Within an evacuated glass jacket two electrodes R and S are enclosed and the light radiation is allowed to enter the jacket through a quartz window. The radiation falls on electrode R, called cathode. The electrode S can be kept at desired (positive or negative) potential with respect to the cathode. A sensitive ammeter is put in the circuit to record current resulting from photoelectrons. The potential difference between the cathode and anode can be measured by voltmeter . Experimental Setup. Experimental observations The experimental observation of photoelectric effect may be summarised as follows; 1) Effect of Intensity of light on Photoelectric current; For a constant potential difference between the cathode ...
Post a Comment
Read more