Negative muons lose their energies in matters via ionization and excitation of atoms, and are trapped in the Coulomb fields formed by nuclei, and finally disappear making nuclear muon capture. The nuclear muon capture is governed by the weak interaction like the other weak processes such as nuclear beta-decays and nuclear electron capture, but is unique because the excitation energy of aa muon-capturing nucleus is as high as 100MeV which corresponds to the invariant mass of the muon. Therefore the nuclear muon capture is expected to be a good probe for the highly excited states of nucleus via weak interaction.
The MuSIC beam line of RCNP provides high-intensity continuos beam of muons.We are studying weak processes related to the nuclear reactions caused by supernova neutrinos, neutrinoless double-beta decays and also three-body problems in nuclei.