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muon

muon (myōō´ŏn), elementary particle heavier than an electron but lighter than other particles having nonzero rest mass. The name muon is derived from mu meson, the former name of the particle. The muon was first observed in cosmic rays by Carl D. Anderson and Seth Neddermeyer in 1936, the year after the existence of a particle of about the same mass had been predicted by Hideki Yukawa. However, the muon's behavior did not conform to that of Yukawa's meson theory (which actually describes the pion, discovered more than 10 years later), and the muon is now classed as a lepton rather than a meson. The muon resembles the electron in every way except mass, the muon having 207 times the mass of the electron. Each particle is negatively charged and has a positively charged antiparticle; each has half-integer spin and participates in the weak nuclear force but not in the strong force; and each has an associated neutrino and antineutrino. Muons are produced by the weak decay of pions into a muon and a muon antineutrino. The muon differs from the electron in that it is unstable, decaying with an average lifetime of 2.2 × 10-6 sec (2.2 microseconds) into an electron or positron and a pair of neutrinos, but this difference is related to the difference in mass; the electron is stable because there is no lighter particle into which it can decay. Muons can be substituted for electrons in orbit around the nucleus of an atom; the resulting atom is long-lived enough to exhibit behavior that further supports the close resemblance between the muon and the electron. Recent studies of muons have included the production of "muonic atoms" (ordinary atoms to which an orbiting muon is added) and muonium, which consists of an electron in orbit around a positive muon.

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"muon." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

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"muon." The Columbia Encyclopedia, 6th ed.. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/muon

muon

mu·on / ˈmyoōˌän/ • n. Physics an unstable subatomic particle of the same class as an electron (a lepton), but with a mass around 200 times greater. Muons make up much of the cosmic radiation reaching the earth's surface. DERIVATIVES: mu·on·ic / myoōˈänik/ adj.

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"muon." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"muon." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/muon

"muon." The Oxford Pocket Dictionary of Current English. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/muon

muon

muon (symbol μ) Negatively charged elementary particle, originally thought to be a meson but now classified as a lepton. It has spin 1/2, a mass c.207 times that of the electron, and decays weakly into an electron, a neutrino, and an antineutrino. See also antimatter

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"muon." World Encyclopedia. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"muon." World Encyclopedia. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/muon

"muon." World Encyclopedia. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/muon