Pair production

Pair production

Pair production (/pɛər prəˈdʌkʃən/) is a fundamental phenomenon in quantum physics that refers to the creation of an elementary particle and its antiparticle, usually when a photon passes close to a nucleus. The term originates from the Latin par, meaning "equal", and the English production, meaning "the act of producing".

Process

In pair production, the energy of the incident photon is converted into mass in the form of an elementary particle and its antiparticle. The most common example is the production of an electron and a positron from a photon. This process can only occur if the energy of the photon is above a certain threshold, which is 1.022 MeV for electron-positron pairs. The excess energy of the photon above this threshold is shared between the kinetic energy of the produced pair.

Conservation Laws

Pair production is governed by several conservation laws, including the conservation of energy, momentum, and charge. The energy of the photon is converted into the mass and kinetic energy of the pair, while the momentum of the photon is shared between the pair and the nucleus. The charge of the photon, which is zero, is conserved by the production of a particle and an antiparticle, which have equal and opposite charges.

Related Phenomena

Pair production is closely related to several other phenomena in quantum physics, including pair annihilation, in which a particle and its antiparticle annihilate each other to produce a photon, and vacuum polarization, in which a photon splits into a pair in a vacuum.

See Also

• Quantum electrodynamics
• Feynman diagram
• Dirac equation

References

• Quantum Physics
• Elementary Particle
• Antiparticle
• Photon
• Nucleus
• Electron
• Positron
• Conservation Laws
• Energy
• Momentum
• Charge
• Pair Annihilation
• Vacuum Polarization
• Quantum Electrodynamics
• Feynman Diagram
• Dirac Equation

External links

• Medical encyclopedia article on Pair production
• Wikipedia's article - Pair production

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