Effects of continuum states on particle emissions from muon captures

Minato, Futoshi   ; Naito, Tomoya*

Nuclei can be at an excited state by muon captures. If the excitation energy is above particle threshold energies, the nuclei emit neutrons and other light particles competing with the gamma deexcitation. The information is important for evaluating soft errors of semi-conductors. Although experimental data of the particle emissions following after muon captures have been reproduced with some phenomenological models, the detailed mechanism with respect to the nuclear structure is still unclear. In particular, experimentally measured neutron spectra after muon capture cannot be reproduced well with a nuclear structure model. In this work, we go into the investigation on this issue with a microscopic approach of proton-neutron random-phase-approximation (RPA) and particle evaporation models considering pre-equilibrium and compound process. We discuss an importance of continuum states of outgoing neutrons in the scheme of RPA.