Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay

Author(s): Collaboration, DB; Adey, D; An, FP; Balantekin, AB; Band, HR; Bishai, M; Blyth, S; Cao, D; Cao, GF; Cao, J; Chan, YL; Chang, JF; Chang, Y; Chen, HS; Chen, SM; Chen, Y; Chen, YX; Cheng, J; Cheng, ZK; Cherwinka, JJ; Chu, MC; Chukanov, A; Cummings, JP; Deng, FS; Ding, YY; Diwan, MV; Dolgareva, M; Dwyer, DA; Edwards, WR; Gonchar, M; Gong, GH; Gong, H; Gu, WQ; Guo, L; Guo, XH; Guo, YH; Guo, Z; Hackenburg, RW; Hans, S; He, M; Heeger, KM; Heng, YK; Higuera, A; Hsiung, YB; Hu, BZ; Hu, JR; Hu, T; Hu, ZJ; Huang, HX; Huang, XT; Huang, YB; Huber, P; Huo, W; Hussain, G; Jaffe, DE; Jen, KL; Ji, XL; Ji, XP; Johnson, RA; Jones, D; Kang, L; Kettell, SH; Koerner, LW; Kohn, S; Kramer, M; Langford, TJ; Lebanowski, L; Lee, J; Lee, JHC; Lei, RT; Leitner, R; Leung, JKC; Li, C; Li, F; Li, HL; Li, QJ; Li, S; Li, SC; Li, SJ; Li, WD; Li, XN; Li, XQ; Li, YF; Li, ZB; Liang, H | Abstract: We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor $\overline{\nu}_{e}$ inverse beta decay candidates observed over 1958 days of data collection. The installation of a Flash-ADC 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 $^9$Li and $^8$He 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 $\overline{\nu}_{e}$ rates and energy spectra among detectors yields $\sin^{2}2\theta_{13} = 0.0856\pm 0.0029$ and $\Delta m^2_{32}=(2.471^{+0.068}_{-0.070})\times 10^{-3}~\mathrm{eV}^2$ assuming the normal hierarchy, and $\Delta m^2_{32}=-(2.575^{+0.068}_{-0.070})\times 10^{-3}~\mathrm{eV}^2$ assuming the inverted hierarchy.