The Improved Measurement of Electron-antineutrino Disappearance at Daya Bay

Understand

With 2.5x the previously reported exposure, the Daya Bay experiment has improved the measurement of the neutrino mixing parameter sin^2(2theta_13) = 0.089+-0.010(stat)+-0.005(syst).

• Reactor anti-neutrinos were produced by six 2.9 GW(th) commercial power reactors, and measured by six 20-ton target-mass detectors of identical design.
• A total of 234,217 anti-neutrino candidates were detected in 127 days of exposure.
• An anti-neutrino rate of 0.944+-0.007(stat)+-0.003(syst) was measured by three detectors at a flux-weighted average distance of 1648 m from the reactors, relative to two detectors at 470 m and one detector at 576 m.