Potential to identify neutrino mass ordering with reactor antineutrinos at JUNO

TL;DR

JUNO aims to determine the neutrino mass ordering by analyzing reactor antineutrino oscillation patterns over 6.5 years, achieving a 3-sigma sensitivity independent of CP phase and mixing angles.

Contribution

This study provides an updated sensitivity estimate for JUNO's ability to identify neutrino mass ordering using reactor antineutrinos, incorporating detailed detector and environmental modeling.

Findings

3σ median sensitivity to mass ordering in 6.5 years

Independent of CP phase and θ23

Utilizes joint analysis of JUNO and TAO detectors

Abstract

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino experiment under construction in South China. This paper presents an updated estimate of JUNO's sensitivity to neutrino mass ordering using the reactor antineutrinos emitted from eight nuclear reactor cores in the Taishan and Yangjiang nuclear power plants. This measurement is planned by studying the fine interference pattern caused by quasi-vacuum oscillations in the oscillated antineutrino spectrum at a baseline of 52.5~km and is completely independent of the CP violating phase and neutrino mixing angle $\theta_{23}$. The sensitivity is obtained through a joint analysis of JUNO and Taishan Antineutrino Observatory (TAO) detectors utilizing the best available knowledge to date about the location and overburden of the JUNO experimental site, local and global nuclear reactors, JUNO and TAO detector responses, expected event rates and spectra of signals and backgrounds, and systematic uncertainties of analysis inputs. We find that a 3$\sigma$ median sensitivity to reject the wrong mass ordering hypothesis can be reached with an exposure to approximately 6.5 years $\times$ 26.6 GW thermal power.