Determination of the Neutrino Mass Hierarchy at an Intermediate Baseline

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 $\Delta m^2_{32}$.