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{{for|other uses|Mu}}
{{no sources|date=October 2011}}
The '''muon''' is an [[elementary particle]]. It has a negative [[electric charge]] and [[Spin (physics)|half spin]]. Its symbol is "μ<sup>-</sup>". It is a type of [[lepton]].

The muon has an average [[Half-life (element)|life time]] of 2.2 [[micro-second]]s or 0.0000022 seconds.<br />
A muon is like an [[electron]], but it is 200 times heavier. Unlike an electron, it decays into other [[particle]]s. The [[Supersymmetry|superparticle]] of a muon is called a "smuon."

== How are muons made? ==
Muons can be made in [[particle accelerator]]s with energy levels above 105.7 MeV. [[Cosmic ray]]s from the [[Sun]] also make muons:
# The [[photons]] in the cosmic rays crash into air [[molecule]]s.
# [[Pions]] are made in the crash
# The pions undergo [[Weak interaction|atomic decay]] into [[neutrino]]s and muons.

==Muon decay==
[[Image:Muon Decay.svg|right|250px|thumb|The most common decay of the muon]]
Muons are unstable elementary particles. They are heavier than electrons and neutrinos but lighter than all other particles. They decay via the [[weak interaction]]. Because the total of the [[lepton number]]s of the starting and ending particles must be the same, one of the product neutrinos of muon decay must be a muon-type neutrino and the other an electron-type antineutrino. Because charge must be kept the same, one of the products of muon decay is always an electron of the same charge as the muon. So, all muons decay to at least an electron, and two neutrinos. Sometimes, besides these necessary products, additional other particles that have a net charge and spin of zero (e.g., a pair of photons, or an electron-positron pair), are produced.

The dominant muon decay mode (sometimes called the Michel decay after [[Louis Michel (physicist)|Louis Michel]]) is the simplest possible: the muon decays to an electron, an electron-antineutrino, and a muon-neutrino. Antimuons, in mirror fashion, most often decay to the corresponding antiparticles: a [[positron]], an electron-neutrino, and a muon-antineutrino.

==Other websites==
* [http://antwrp.gsfc.nasa.gov/apod/ap050828.html Muon anomalous magnetic moment and supersymmetry]
* [http://www.g-2.bnl.gov/ g-2 (muon anomalous magnetic moment) experiment]
* [http://www.npl.uiuc.edu/exp/mulan/ muLan (Measurement of the Positive Muon Lifetime) experiment] {{Webarchive|url=https://web.archive.org/web/20060902054947/http://www.npl.uiuc.edu/exp/mulan/ |date=2006-09-02 }}
* [http://pdg.lbl.gov/ The Review of Particle Physics]
* [http://twist.triumf.ca/ The TRIUMF Weak Interaction Symmetry Test]
* [http://meg.psi.ch/ The MEG Experiment (Search for the decay Muon → Positron + Gamma)] {{Webarchive|url=https://web.archive.org/web/20020325192213/http://meg.psi.ch/ |date=2002-03-25 }}

{{Leptons}}
{{Elementary}}


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[[Category:Elementary particles]]