ABSTRACT

We report an updated neutrino mixing angle of θ13 obtained from a complete data sample of the RENO experiment. The experiment has measured the amplitude and frequency of reactor electron antineutrino (ν¯e) oscillations at the Hanbit nuclear power plant, Younggwang, Korea, since August 2011. As of March 2023, the data acquisition was completed after a total of 3800 live days of detector operation. The observed candidates via inverse beta decay with the neutron capture on the gadolinium channel are 1,211,995 (144,667) in the near (far) detector. Based on an observed energy-dependent reactor neutrino disappearance, neutrino oscillation parameters of θ13 and jΔm2 eej are precisely determined as sin22θ13 ¼ 0.0920þ0.0044 −0.0042 ðstatÞ þ0.0041 −0.0041 ðsystÞ and jΔm2 eej¼½2.57þ0.10 −0.11 ðstatÞ þ0.05 −0.05 ðsystÞ × 10−3 eV2. Compared to the previously published RENO results, the precision is improved from 7.5% to 6.4% for sin2 2θ13 and from 5.2% to 4.5% for jΔm2 eej. The statistical error of the measurement has reached our goal and is hardly improved with additional data taking.