Table of Contents
- 1 Why pair production does not occur in empty space?
- 2 Why are two photons produced in annihilation?
- 3 Why pair production happens?
- 4 What causes pair production?
- 5 Why does annihilation occur?
- 6 Is pair production possible in vacuum?
- 7 Where does pair production take place in physics?
- 8 How is photon energy related to pair production?
Why pair production does not occur in empty space?
@Lin Zhang, in the case of pair production in vacuum, it is impossible to satisfy both momentum and energy conservation, or if momentum is conserved, not so is energy. If you have only one photon than the QED vertex that would describe the pair production is forbidden because it violates momentum conservation.
What are the factors affecting the probability of occurrence of pair production?
The probability for pair production rises with the incident photon energy. Any photon energy in excess of 1.022 MeV will be distributed between the kinetic energies of electron and positron and the recoiling nucleus.
Why are two photons produced in annihilation?
Annihilation occurs when a particle and a corresponding antiparticle meet and their mass is converted into radiation energy. Two photons are produced in the process (as a single photon only would take away momentum which isn’t allowed, as no outside forces act).
Why pair production Cannot take place if the frequency of the photon is below a certain value?
E = hf so the energy of photon is proprtional to its frequency. When pair production occurs the energy is converted to mass according to the equation E = mc2. If the energy/frequency is below the conversion to the mass/rest energy of the particle and antiparticle pair the event will not occur.
Why pair production happens?
Pair production is a direct conversion of radiant energy to matter. It is one of the principal ways in which high-energy gamma rays are absorbed in matter. Photon energy in excess of this amount, when pair production occurs, is converted into motion of the electron-positron pair.
What is annihilation process?
In particle physics, annihilation is the process that occurs when a subatomic particle collides with its respective antiparticle to produce other particles, such as an electron colliding with a positron to produce two photons.
What causes pair production?
For pair production to occur, the electromagnetic energy, in a discrete quantity called a photon, must be at least equivalent to the mass of two electrons. The positron that is formed quickly disappears by reconversion into photons in the process of annihilation with another electron in matter.
What is pair production gives example?
Pair production is the creation of a subatomic particle and its antiparticle from a neutral boson. Examples include creating an electron and a positron, a muon and an antimuon, or a proton and an antiproton. Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus.
Why does annihilation occur?
What kind of photon is required for pair production?
What kind of photon is required for the pair production phenomenon to occur? Explanation: When a γ-ray Photon passes close to an atomic nucleus (b < R) and it possesses energy greater than 1.02 MeV, the photon is converted into electron-positron pair. This is called pair production.
Is pair production possible in vacuum?
Originally Answered: why does pair production cannot occur in vacuum? Photons, from which pairs are created, have both energy & momentum, neither of which can be zero. When a pair is created from the photon the total energy of the pair must equal the original photon energy, which is fine.
What happens in pair production with the nucleus?
In a pair production with the nucleus, the recoil energy to the nucleus may be neglected and the positron and the electron will get the photon energy minus the rest mass energy of the electron and positron pair. The function g ( hν, E+′, Z) increases with increasing hν and decreases slightly with increasing Z.
Where does pair production take place in physics?
Pair production, in physics, formation or materialization of two electrons, one negative and the other positive (positron), from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus.
How does pair production occur in electron positron?
Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created.
The photon passing the Coulomb field of a nucleus transforms into an electron–positron pair. The probability for pair production rises with the incident photon energy. Any photon energy in excess of 1.022 MeV will be distributed between the kinetic energies of electron and positron and the recoiling nucleus.