Energy spectra of neutrons emitted following muon capture in 16O and 12C

The energy spectra of neutrons emitted following muon capture in 16O and 12C are investigated using the continuum shell model. Nuclear wave functions, which have been shown by Ohtsubo and the author to describe the radiative pion capture reaction in the above nuclei well, are adopted. The calculated neutron energy spectra explain well the observed main peaks, at 5 MeV for 16O and 4 MeV for 12C, which are considered to be the giant resonces excited in the muon capture reaction. These peaks are interpreted as the 2- state at 20.3 MeV for 16O and the 1- state at 22.5 MeV for 12C. Comparisons with photon spectra in radiative pion capture reactions are also made. The calculated total capture rates exceed the experimental values by a factor of 2.5 for 16O and by 30-40% for 12C. (orig.)