Muon capture is the capture of a negative muon by a proton, usually resulting in production of a neutron and a neutrino, and sometimes a gamma photon.
Except for the flavor of neutrino, it has exactly the same result as electron capture, except that the great mass-energy of the muon makes it allowed for all nuclei and there is so much excess energy that a nucleus can disintegrate; for heavy nuclei this leads to emission of nuclear particles; most often neutrons, but charged particles can be emitted as well.
Ordinary muon capture (OMC) involves capture of a negative muon from the atomic orbital without emission of a gamma photon:
Radiative muon capture (RMC) is a radiative version of OMC, where a gamma photon is emitted:
Theoretical motivation for the study of muon capture on the proton is its connection to the proton's induced pseudoscalar form factor g<sub>p</sub>.
Muon capture is being investigated for practical application in radioactive waste disposal, for example in the artificial transmutation of large quantities of long-lived radioactive waste that have been produced globally by fission reactors. Radioactive waste can be transmuted to stable isotopes following irradiation by an incident muon () beam from a compact proton accelerator source.