We have observed eleven events of the reaction ${\nu }_{\mu }{e}^{-}\to {\nu }_{\mu }{e}^{-}$ in a sample of 106 000 charged-current neutrino interactions in a heavy neon-hydrogen mixture in the 15-ft. bubble chamber at Fermilab. We obtain a cross section for this process of $\left[\right(1.8\mathrm{}\pm 0.8)\times {10}^{-42\mathrm{}} {\mathrm{cm}}^2/\mathrm{GeV}]E_{\nu }$. This result is in good agreement with the prediction of the Weinberg-Salam model with ${{sin}^2\theta }_W=0.2\mathrm{}$.

• Received 16 June 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.357