Determination of the Neutrino Mass Hierarchy at an Intermediate Baseline

TL;DR

This paper proposes a more sensitive Fourier analysis method for intermediate baseline reactor neutrino experiments, enabling neutrino mass hierarchy determination with smaller mixing angles and less dependence on spectral details.

Contribution

It introduces an improved Fourier analysis technique that enhances the sensitivity of intermediate baseline experiments to neutrino mass hierarchy.

Findings

Can identify mass hierarchy for $ heta_{13}$ with $ ext{sin}^2(2 heta_{13}) > 0.005$

Does not require precise reactor neutrino spectrum knowledge

Effective at a baseline of approximately 60 km

Abstract

It is generally believed that neutrino mass hierarchy can be determined at a long baseline experiment, often using accelerator neutrino beams. Reactor neutrino experiments at an intermediate baseline have the capability to distinguish normal or inverted hierarchy. Recently it has been demonstrated that the mass hierarchy could possibly be identified using Fourier transform to the L/E spectrum if the mixing angle $\sin^2(2\theta_{13})>0.02$. In this study a more sensitive Fourier analysis is introduced. We found that an ideal detector at an intermediate baseline ($\sim 60$ km) could identify the mass hierarchy for a mixing angle $\sin^2(2\theta_{13}) > 0.005$, without requirements on accurate information of reactor neutrino spectra and the value of $\Delta m^2_{32}$.