Measurement of reactor antineutrino flux and spectrum at RENO

The RENO experiment reports measured flux and energy spectrum of reactor electron antineutrinos ${\overline{\ensuremath{\nu}}}_{e}$ from the six reactors at Hanbit Nuclear Power Plant. The measurements use 966 094 $116\text{ }111{\overline{\ensuremath{\nu}}}_{e}$ candidate events with a background fraction of 2.39% (5.13%), acquired in the near (far) detector, from August 2011 to March 2020. The inverse beta decay (IBD) yield is measured as $(5.852\ifmmode\pm\else\textpm\fi{}0.094)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}43}\text{ }\text{ }{\mathrm{cm}}^{2}/\mathrm{fission}$, corresponding to $0.941\ifmmode\pm\else\textpm\fi{}0.015$ of the prediction by the Huber and Mueller (HM) model. A reactor ${\overline{\ensuremath{\nu}}}_{e}$ spectrum is obtained by unfolding a measured IBD prompt spectrum. The obtained neutrino spectrum shows a clear excess around 6 MeV relative to the HM prediction. The obtained reactor ${\overline{\ensuremath{\nu}}}_{e}$ spectrum will be useful for understanding unknown neutrino properties and reactor models. The observed discrepancies suggest the next round of precision measurements and modification of the current reactor ${\overline{\ensuremath{\nu}}}_{e}$ models.