Search for muon-neutrino oscillations ν_μ→ν_e (ν¯_μ→ν¯_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 ν_e (ν¯_e), 1 km from the source of a wide-band ν_μ (ν¯_μ) beam. The experiment used a total of 3×10¹⁹ 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 ν_e or ν¯_e over the expected backgorund was detected. The 90%-confidence-level limits obtained are Δm²≤0.075 eV² for maximal mixing, and sin²2θ≤0.003 for large Δm².