Expected performance of a water Cherenkov detector for reactor antineutrino--electron scattering

Abstract

We evaluate the expected performance of a 170-ton water Cherenkov detector for reactor antineutrino--electron elastic scattering at the RENO near-detector site. The reactor-spectrum normalization is extracted from the reconstructed recoil-electron directional distribution using a constrained profile-likelihood fit for an exposure of 365.25 days. For the minimum prompt-hit multiplicity $N_{\mathrm{prompt}}\ge 8$ scenario, which neglects PMT radioactivity, the total uncertainty on the reactor-spectrum normalization is ${}_{-1.07\%}^{+1.08\%}$. For the more restrictive $N_{\mathrm{prompt}}\ge 20$ scenario, which includes the simulated PMT-radioactivity components, the total uncertainty is ${}_{-1.47\%}^{+1.49\%}$. These results demonstrate that directional information from a water Cherenkov detector can provide percent-level sensitivity to the reactor elastic-scattering normalization.

32 pages, 12 figures