We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor νe inverse β decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic Li9 and He8 background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative νe rates and energy spectra among detectors yields sin22θ13=0.0856±0.0029 and Δm322=(2.471-0.070+0.068)×10-3 eV2 assuming the normal hierarchy, and Δm322=-(2.575-0.070+0.068)×10-3 eV2 assuming the inverted hierarchy.
ASJC Scopus subject areas
- Physics and Astronomy(all)