Encyclopedia > Muon

  Article Content

Muon

According to the Standard Model of particle physics, a muon (also known as a mu meson) is a collective name for two semistable fundamental particles with positive and negative charge. Muons have a mass that is 207 times greater than the electron (105.6 MeV) and a spin of 1/2. Both electrons and muons belong to to the same family of fermions (i.e., fundamental particles) called the leptons. Because of this, a negatively-charged muon can be thought of as an extremely heavy electron. Muons are denoted by μ- and μ+ depending on their charge.

On earth, muons are created when a charged pion decays. The pions are created in an upper atmosphere by cosmic radiation and have a very short decay time--a few nanoseconds. The mouns created when the pion decays are also short-lived: their decay time is 2.2 microseconds. However, the muons have high energies, so the time dilation[?] effects of special relativity make them easily detectable at the earth's surface.

As with the case of electrons there is a muon neutrino which is associated with the muon. Muon neutrinos are denoted by νμ.

Positive muons can form a particle called muonium, or μ+e. Due to the mass difference between the muon and the electron, muonium is more similar to atomic hydrogen than positronium.

Reference: Serway & Faughn, College Physics, Fourth Edition (Fort Worth TX: Saunders, 1995) page 841



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
List of wine producing regions

... Chile 2.4 United States 2.5 Mexico 3 Asia Pacific 3.1 Australia 3.2 New Zealand 4 Europe 4.1 Austria 4.2 Bulgaria 4.3 Cyprus 4.4 Czechia 4.5 France 4.6 ...