Muon-neutrino carbon charged-current interaction near the muon threshold

A measurement of the muon-neutrino carbon charged-current cross section, C-12(nu(mu),mu-)X, was performed using the in-flight pion-decay neutrino source at the LAMPF accelerator. At an average interacting neutrino energy of 202 MeV an inclusive cross section of (15.9+/-2.6+/-3.7) X 10(-39) cm2 Was measured. This value is in best agreement with the Fermi-gas model and is in disagreement with a previous experiment and subsequent calculations that yielded substantially lower cross sections. However, the muon energy spectrum shows a marked depletion of events at high energies compared to the Fermigas model. From a small sample of events in which the final-state nucleus was in the ground state of N-12, a cross section for the reaction C-12(nu(mu),mu-)N-12(g.s.) of (1.7+/-0.8+/-0.3) X 10(-39) CM2 or about 11+/-5 % of the total event rate was obtained.