# pair production

pair production
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.

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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. 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.

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Universalium. 2010.

### См. также в других словарях:

• Pair production — Pair pro*duc tion (Physics) The simultaneous creation of a particle and its antiparticle, such as an electron and positron, from a photon; usually due to its interaction with the strong field near a nucleus. [PJC] …   The Collaborative International Dictionary of English

• pair production — n. a process whereby a gamma ray having an energy greater than 1.02 MeV is converted into an electron and positron pair in the strong electric field of a nucleus …   English World dictionary

• Pair production — Light–matter interaction Low energy phenomena …   Wikipedia

• pair production — porų susidarymas statusas T sritis fizika atitikmenys: angl. pair creation; pair formation; pair production vok. Paarbildung, f; Paarerzeugung, f rus. образование пар, n; рождение пар, n pranc. création de paires, f; formation des paires, f;… …   Fizikos terminų žodynas

• pair production — noun the transformation of a gamma ray photon into an electron and a positron when the photon passes close to an atomic nucleus • Syn: ↑pair creation, ↑pair formation • Hypernyms: ↑natural process, ↑natural action, ↑action, ↑activity …   Useful english dictionary

• pair production — /ˈpɛə prədʌkʃən/ (say pair pruhdukshuhn) noun 1. the simultaneous creation of a positron and an electron as the result of the interaction between a high energy photon or particle and the field of an atomic nucleus. 2. the simultaneous creation of …   Australian-English dictionary

• pair production — noun Date: 1934 the transformation of a quantum of radiant energy simultaneously into an electron and a positron when the quantum interacts with the intense electric field near a nucleus …   New Collegiate Dictionary

• pair production — noun Physics the conversion of a gamma ray into an electron and a positron …   English new terms dictionary

• pair-production cross-section — poros susidarymo skerspjūvis statusas T sritis fizika atitikmenys: angl. pair creation cross section; pair generation cross section; pair production cross section vok. Paarbildungsquerschnitt, m; Paarbildungswirkungsquerschnitt, m rus. парное… …   Fizikos terminų žodynas

• pair-production coefficient — porų susidarymo koeficientas statusas T sritis fizika atitikmenys: angl. pair creation coefficient; pair production coefficient vok. Paarbildungskoeffizient, m rus. коэффициент образования пар, m pranc. coefficient de la production de paires, m …   Fizikos terminų žodynas

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