New Results from the Daya Bay Reactor Neutrino Experiment

Abstract

This presentation describes a precision result of the neutrino mixing parameter, $\sin^2 2\theta_{13}$, and the first direct measurement of the antineutrino mass-squared difference $\sin^2(\Delta_{ee}) \equiv \cos^2 \theta_{12} \sin^2 \Delta_{31} + \sin^2 \theta_{12} \sin^2 \Delta_{32}$ from the Daya Bay Reactor Neutrino Experiment. The above results are based on the six detector data-taking from 24 December 2011 to 28 July 2012. By using the observed antineutrino rate and the energy spectrum analysis, the results are $\sin^2 2\theta_{13}=0.090^{+0.008}_{-0.009}$ and $| \Delta m^2_{ee}| = 2.59^{+0.19}_{-0.20} \cdot 10^{-3} $eV$^2$ with a $\chi^2$/NDF of 162.7/153. The value of $| \Delta m^2_{ee}| $ is consistent with $| \Delta m^2_{\mu\mu}|$ measured in muon neutrino beam experiments.