A search for νμ oscillations in the Δm2 range 0.3–90 eV2

Abstract We have searched for ν μ oscillations by comparing the rates of ν gm charged-current interactions in two detectors located 130 and 885 m from the target, which was struck by a 9.2 GeV/ c proton beam from the CERN Proton Synchroton. No evidence for ν μ oscillations was found. At the 90% confidence level, Δm 2 values between 0.26 and 90 eV 2 are excluded for maximal mixing. The most restrictive limit on the neutrino mixing-angle parameter sin 2 2 θ is 0.053 at Δm 2 =2.5 eV 2 .