Pair production

Pair production is the creation of an electron and a positron, a specific type of particle-antiparticle pair, from a photon.

Overview

When a photon interacts with a nucleus, it can transform into an electron and a positron. This process is known as pair production. The photon must have a minimum energy of 1.022 MeV to create a pair, which is the total rest mass energy of an electron and a positron. The photon's energy is converted into mass according to Einstein's equation, E=mc^2.

Process

In pair production, a photon disappears and an electron-positron pair is created. The photon must be in the vicinity of a nucleus for this process to occur, to conserve momentum. The nucleus absorbs the recoil momentum of the process. The electron and positron that are created will have kinetic energy equal to the energy of the original photon minus 1.022 MeV.

Conservation Laws

Pair production obeys several conservation laws, including the conservation of charge, linear momentum, angular momentum, and energy. The electron and positron have opposite charges, so the total charge before and after the reaction is zero. The linear and angular momentum of the photon is carried away by the electron, positron, and nucleus. The energy of the photon is shared between the kinetic energy of the electron, positron, and the recoil of the nucleus.

See also

• Photon
• Electron
• Positron
• Nucleus
• Momentum
• Energy

Pair production Resources
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