Systematic impact of spent nuclear fuel on θ₁₃ sensitivity at reactor neutrino experiment

Abstract: 

Reactor neutrino oscillation experiments, such as Daya Bay, Double Chooz and RENO are designed to determine the neutrino mixing angle θ₁₃ with a sensitivity of 0.01—0.03 in sin²2θ₁₃ at 90% confidence level, an improvement over the current limit by more than one order of magnitude. The control of systematic uncertainties is critical to achieving the sin²2θ₁₃ sensitivity goal of these experiments. Antineutrinos emitted from spent nuclear fuel (SNF) would distort the soft part of energy spectrum and may introduce a non-negligible systematic uncertainty. In this article, a detailed calculation of SNF neutrinos is performed taking account of the operation of a typical reactor and the event rate in the detector is obtained. A further estimation shows that the event rate contribution of SNF neutrinos is less than 0.2% relative to the reactor neutrino signals. A global χ² analysis shows that this uncertainty will degrade the θ₁₃ sensitivity at a negligible level.