Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam

TL;DR

This paper reports evidence of neutrino oscillations based on the observation of electron anti-neutrinos in a muon anti-neutrino beam, supporting the existence of neutrino mass differences in the 0.2-10 eV^2 range.

Contribution

First experimental evidence of muon anti-neutrino to electron anti-neutrino oscillations using a liquid scintillator detector at Los Alamos.

Findings

87.9 +/- 22.4 +/- 6.0 excess events observed

Oscillation probability of 0.264 +/- 0.067 +/- 0.045

Supports neutrino mass > 0.4 eV/c^2

Abstract

A search for muon anti-neutrino to electron anti-neutrino oscillations was conducted by the Liquid Scintillator Neutrino Detector at the Los Alamos Neutron Science Center using muon anti-neutrinos from positive muon decay at rest. A total excess of 87.9 +/- 22.4 +/- 6.0 events consistent with electron anti-neutrino plus proton scattering to positron plus neutron was observed above the expected background. This excess corresponds to an oscillation probability of (0.264 +/- 0.067 +/- 0.045), which is consistent with an earlier analysis. In conjunction with other known limits on neutrino oscillations, the LSND data suggest that neutrino oscillations occur in the 0.2-10 eV^2/c^4 Delta-m^2 range, indicating a neutrino mass greater than 0.4 eV/c^2.