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Physics. the simultaneous creation of a particle and its antiparticle by a nucleus or particle in an excited state, as when a photon is absorbed.[1930-35]
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Formation of an electron and a positron from high-energy electromagnetic radiation traveling through matter, usually in the vicinity of an atomic nucleus.It is a direct conversion of radiant energy into matter in accordance with the equation E = mc2, where E is the amount of energy, m is the mass, and c is the speed of light. It is one of the principal ways in which high-energy gamma rays are absorbed in matter. The positrons quickly disappear by being reconverted into photons in the process of annihilation with other electrons. Pair production may sometimes refer to the formation of other particle/antiparticle pairs as well.* * *
▪ physicsin 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. Pair production is a direct conversion of radiant energy to matter. It is one of the principal ways in which high-energy gamma rays (gamma ray) are absorbed in matter. 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 mass m of a single electron is equivalent to 0.51 million electron volts (MeV) of energy E as calculated from the equation formulated by Albert Einstein, E = mc2, in which c is a constant equal to the velocity of light. To produce two electrons, therefore, the photon energy must be at least 1.02 MeV. Photon energy in excess of this amount, when pair production occurs, is converted into motion of the electron-positron pair. If pair production occurs in a track detector, such as a cloud chamber, to which a magnetic field is properly applied, the electron and the positron curve away from the point of formation in opposite directions in arcs of equal curvature. In this way pair production was first detected (1933). The positron that is formed quickly disappears by reconversion into photons in the process of annihilation with another electron in matter.internal pair production, a species of gamma decay (q.v.), occurs when an unstable nucleus that has at least 1.02 MeV of excess energy directly ejects an electron-positron pair created within its own electromagnetic field without first producing a gamma photon.* * *
Universalium. 2010.