Observation ofμ−e+KS0Events Produced by a Neutrino Beam

Four events have been observed with an $e^{+}$ and a ${K_s}^0$ decay in the final state induced by a neutrino beam incident on the Fermilab 15-ft neon bubble chamber. Conventional backgrounds are unable to account for these events. Two of the events have in addition a ${\mu }^{-}$ in the final state clearly identified by the external muon identifier. The other two have ${\mu }^{-}$ candidates.