Measurement of reactor antineutrino flux and spectrum at RENO
S. G. Yoon, H. Seo, Z. Atif, J. H. Choi, H. I. Jang, Jinhyeok Jang, S. H. Jeon, K. K. Joo, K. Ju, D. E. Jung, J. G. Kim, J. H. Kim, J. Y. Kim, S. B. Kim, S. Y. Kim, Woo Kim, E. Kwon, Daniel J. Lee, H. G. Lee, I. T. Lim, D. H. Moon, M. Y. Pac, J. W. Seo, C. D. Shin, B. S. Yang, J. Yoo, I. S. Yeo, I. Yu
Abstract
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.