|MadSci Network: Physics|
Dear Evan, You asked what the velocity of a muon expelled from atom is, and from where they are expelled. I'm afraid I don't understand your question. Muons are inherently unstable, and decay quite rapidly. Thus, to get a muon to be expelled from an atom, one would have to be made somehow inside the nucleus. To the best of my knowledge, there are no radioactive decays that cause a nucleus to emit a muon (basically, it would violate the conservation of energy and lepton number). So I can't see it happening. *HOWEVER!* If one were to be emitted, it would most likely be within a few percent of the speed of light. I'm also unclear what you mean by 'where they are expelled'. The atom is symmetric, which means it has no preferred axis, and the muon can come out anywhere. Sorry for not being of much help!
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