A muonium particle is an exotic atom made up of a positive muon and an electron, and is given the symbol Mu or μ+e–. During the muon's 2 microsecond lifetime, muonium can enter into compounds such as muonium chloride (MuCl) or sodium muonide (NaMu). 
Due to the mass difference between the muon and the electron, muonium is more similar to atomic hydrogen than positronium. Muonium has been used to produce muon-catalyzed fusion in which muons shield the positive charge of the nuclei so that the nuclei can fuse.
- "Names for muonium and hydrogen atoms and their ions". (PDF)
Last updated: 05-24-2005 14:17:38