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

A measurement of the muon-neutrino carbon charged-current cross section, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${\nu }_{\mathrm{\mu }}$,${\mathrm{\mu }}^{\mathrm{-}}$)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)×${10}^{\mathrm{-}39}$ ${\mathrm{cm}}^2$ 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 Fermi-gas model. From a small sample of events in which the final-state nucleus was in the ground state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$, a cross section for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${\nu }_{\mathrm{\mu }}$,${\mathrm{\mu }}^{\mathrm{-}}$ ${)}^{12}$N(g.s.) of (1.7±0.8±0.3)×${10}^{\mathrm{-}39}$ ${\mathrm{cm}}^2$ or about 11±5 % of the total event rate was obtained.