muonn.
/ˈmjuːɒn/, U.S. /ˈmjuˌɑn/ Particle Physics.
An unstable, negatively charged lepton having a spin of ½ and a mass of about 105.7 MeV (approx. 207 times that of the electron), which decays to form an electron, a muon neutrino, and an electron antineutrino, and which is the chief constituent of cosmic radiation at the earth's surface. Also: the positively charged antiparticle corresponding to this.Originally called a mu-meson (but now no longer classed as a meson).
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mu-meson1947
muon1951
1951 E. Fermi Elem. Particles i. 3 The μ-meson of Powell (called here muon) is instead a disintegration product of the pion.
1961 Guardian 21 Jan. 2/4 Muons were first discovered in the naturally occurring cosmic rays and identified precisely in 1947..at Bristol University.
1972 Nature 14 July 86/1 The mass difference of the electron and muon poses one of the inscrutable problems of particle physics. Except for the mass difference the muon does not appear to be any different from the electron.
2001 New Scientist (Nexis) 17 Feb. 9 A tiny discrepancy in the magnetism of the muon, a rare subatomic particle, may signal a crack in the standard model of particle physics.
Compounds
muon neutrino n. a type of neutrino associated with reactions involving muons (one of the three known types of neutrino); also called mu-neutrino.
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1959 Žurnal Eksperimental′noj i Teoretičeskoj Fiziki 37 1751 (title) Electron and muon neutrinos.
1962 Nucl. Physics 5 311 The possibility of the muon neutrino having..just as the muon, an f-interaction is discussed.
1998 Sci. Amer. Aug. 9/2 About 0.1 eV now seems to many physicists a likely mass for the muon-neutrino.
muon number n. a quantum number assigned to subatomic particles that is ±1 for muons and their neutrinos and 0 for other particles, and is conserved in all known interactions.
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the world > matter > physics > atomic physics > particle physics > particle avoiding strong interaction > muon > [noun] > quantum number of
muon number1961
1961 Physical Rev. 123 1439/2 The possibility of essentially imaginary relative parities can only arise when some quantum number (here, muon number) is multiplicatively conserved.
1995 Jrnl. Physics G 21 1123 Some observables as fluctuations in the muon number..have been obtained.
This entry has been updated (OED Third Edition, March 2003; most recently modified version published online March 2022).
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