Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2 × 10^(−4) ≲ |Δm^2_(41)| ≲0.3  eV^2 mass range. The resulting limits on sin^2 2θ_(14) are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm^2_(41)| ≲ 0.2  eV^2 region.