Search for muon-neutrino oscillations ${\nu }_{\mathrm{\mu }}$→${\nu }_{\mathit{e}}$ (ν${\mathrm{¯}}_{\mathrm{\mu }}$→ν${\mathrm{¯}}_{\mathit{e}}$) in a wide-band neutrino beam

We present the results of a search for neutrino oscillations at the Brookhaven National Laboratory. The experiment searched for the appearance of ${\nu }_{\mathit{e}}$ (ν${\mathrm{¯}}_{\mathit{e}}$), 1 km from the source of a wide-band ${\nu }_{\mathrm{\mu }}$ (ν${\mathrm{¯}}_{\mathrm{\mu }}$) beam. The experiment used a total of 3×${10}^{19}$ protons on target from the Alternating Gradient Synchrotron. The data collecting was split evenly between positive and negative horn polarities, corresponding to neutrino and antineutrino beams. No excess of ${\nu }_{\mathit{e}}$ or ν${\mathrm{¯}}_{\mathit{e}}$ over the expected backgorund was detected. The 90%-confidence-level limits obtained are Δ${\mathit{m}}^2$≤0.075 ${\mathrm{eV}}^2$ for maximal mixing, and ${\sin }^2$2θ≤0.003 for large Δ${\mathit{m}}^2$.