Search for Neutrino Oscillations in the Appearance Mode nu/sub mu / Yields nu/sub e/ for Neutrino Energies Near the Muon Threshold

摘要

To investigate the possibility of neutrino oscillation, a search for the exclusive mode, nu/sub mu / -> nu/sub e/, was performed at LAMPF. The reactions studied were nu/sub mu / + C -> mu sup - + X; mu sup - -> e sup - + anti nu/sub e/ + nu/sub mu /, and nu/sub e/ + C -> e sup - + X (if nu/sub mu / -> nu/sub e/). The detector was located at an effective distance of 20 m from the water target. The beam was composed primarily of muon-neutrinos from pion decay, and the neutrino flux (of mean energy 150 MeV) was computed to be 6.2 x 10 sup 5 nu/cm sup 2 -sec for 20 mu A of proton beam on our target. We saw no evidence for oscillations, and were able to set upper limits sin sup 2 (2THETA) less than or equal to 8.8 x 10 sup -3 (90% C.L.) (in the limit of large delta m sup 2 ) and delta m sup 2 sin(2THETA) less than or equal to 0.59 eV sup 2 (in the limit of small delta m sup 2 ). (ERA citation 12:046503)