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A search for ν̄μ→ν̄e oscillations has been conducted at the Los Alamos Meson Physics Facility using ν̄μ from μ+ decay at rest. The ν̄e are detected via the reaction ν̄ep→e+n, correlated with the 2.2 MeV γ from np→dγ. The use of tight cuts to identify e+ events with correlated γ rays yields 22 events with e+ energy between 36 and 60 MeV and only 4.6±0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1×10-8. A χ2 fit to the entire e+ sample results in a total excess of 51.0+20.2-19.5±8.0 events with e+ energy between 20 and 60 MeV. If attributed to ν̄μ→ν̄e oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of (0.31±0.12±0.05)%.

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Physical Review C - Nuclear Physics

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