We have studied the quasielastic reaction ${\nu }_{\mu }n\to {\mu }^{-}p$ in an exposure of the Fermilab deuterium-filled 15-foot bubble chamber to a high-energy wide-band neutrino beam. From an analysis of the $Q^2$ distribution based on the standard $V-A$ theory, the axial-vector mass in a dipole parametrization of the axial-vector form factor is determined to be $M_A={1.05}_{-0.16\mathrm{}}^{+0.12\mathrm{}}$ GeV, consistent with the values previously reported from low-energy experiments.

• Received 13 December 1982

DOI:https://doi.org/10.1103/PhysRevD.28.436