An Etymological Dictionary of Astronomy and Astrophysics

A → subatomic particle produced when → primary cosmic rays, impinge on the Earth’s atmosphere producing a particle cascade, in which secondary particles decay into → muons. In the energy range up to 100 → GeV atmospheric muons come mostly from the decay of secondary → pions:
π^±→ μ^± + anti-ν_μ.

At higher energies, the → kaon contribution to the muon flux become significant, reaching the asymptotic value of 27% at about 10 TeV:

K^±→ μ^± + anti-ν_μ.

See also: → atmospheric; → muon.