The RENO experiment has observed the disappearance of reactor electron
antineutrinos, consistent with neutrino oscillations, with a significance of
6.3 standard deviations. Antineutrinos from six 2.8 GW$_{th}$ reactors at
Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors
located at 294 m and 1383 m, respectively, from the reactor array center. In
the 229 day data-taking period of 11 August 2011 to 26 March 2012, the far
(near) detector observed 17102 (154088) electron antineutrino candidate events
with a background fraction of 4.9% (2.7%). A ratio of observed to expected
number of antineutrinos in the far detector is $0.922 \pm 0.010({\rm stat.})
\pm 0.008({\rm syst.})$. From the deficit, we find $\sin^2 2 \theta_{13} =
0.103 \pm 0.013({\rm stat.}) \pm 0.011({\rm syst.})$ based on a rate-only
analysis. \\ ( http://arxiv.org/abs/1204.0626 ,  1541kb)