Observation of Reactor Electron Antineutrinos Disappearance in the RENO Experiment

Authors: J. K. Ahn, Sergey Chebotaryov, J. H. Choi, S. Choi, Won Tae Choi, Y. Choi, H. I. Jang, J. S. Jang, E. J. Jeon, In Seok Jeong, K. K. Joo, B. R. Kim, B C Kim, H. S. Kim, J. Y. Kim, S. B. Kim, S. H. Kim, Sangyong Kim, Woo Kim, Y. D. Kim, Joonhee Lee, J. K. Lee, I. T. Lim, K. J., M. Y. Pac, I. G. Park, J. S. Park, K. S. Park, Jonghwa Shin, K. Siyeon, B. S. Yang, I. S. Yeo, Sangwha Yi, I. Yu - Physical Review Letters 2012 cited by 1,881

The RENO experiment has observed the disappearance of reactor electron antineutrinos, consistent with neutrino oscillations, with a significance of 4.9 standard deviations. Antineutrinos from six $2.8\text{ }\text{ }{\mathrm{GW}}_{\mathrm{th}}$ reactors at the Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors located at 294 and 1383 m, respectively, from the reactor array center. In the 229 d data-taking period between 11 August 2011 and 26 March 2012, the far (near) detector observed 17102 (154088) electron antineutrino candidate events with a background fraction of 5.5% (2.7%). The ratio of observed to expected numbers of antineutrinos in the far detector is $0.920\ifmmode\pm\else\textpm\fi{}0.009(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.014(\mathrm{syst})$. From this deficit, we determine ${sin }^{2}2{\ensuremath{\theta}}_{13}=0.113\ifmmode\pm\else\textpm\fi{}0.013(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.019(\mathrm{syst})$ based on a rate-only analysis.