I read many years ago that muons captured by nuclei with Z>10 react with these nuclei faster than their simple decay. In other words, such reactions as muon + Fe-56 --> Mn-56 + muon-neutrino are faster than the simple decay of the muon to electron, muon-neutrino and electron-antineutrino. I expected this reaction, which is analagous to EC as in Be-7, because the muon orbits much closer to the nucleus than an electron (and in high-Z nuclei the muon orbital is largely within the nucleus); also the energy available to drive this reaction is of the order of 100 Mev, not the few Mev available to drive EC reactions. Yet my internet search on muonic atoms has turned up no mention of such reactions. Am I mistaken? I am interested because if muons do react with heavy nuclei, traces of noble gases should appear through muon interaction with the lightest stable isotopes of Sr and Ba in minerals of these; if these isotopes capture muons the resulting Rb and Cs nuclides largely decay to Kr and Xe: Sr-84 + muon ---> Rb-84 + muon-neutrino; then most of Rb-84 decays by beta+ or EC to Kr-84. Analagous reactions with Ba-130 and Ba-132 should generate Xe-130 and Xe-132.