Mass Hierarchy Resolution in Reactor Anti-neutrino Experiments: Parameter Degeneracies and Detector Energy Response

TL;DR

This paper analyzes the challenges in determining the neutrino mass hierarchy using reactor experiments at 60 km, focusing on detector energy response, parameter degeneracies, and comparing analysis methods.

Contribution

It introduces a Fourier transformation method and emphasizes the importance of precise detector energy scale calibration for successful hierarchy determination.

Findings

Fourier method offers advantages over standard chi-squared analysis.

Energy scale non-linearity must be understood to within a few tenths of a percent.

Parameter degeneracies impact the measurement accuracy.

Abstract

Determination of the neutrino mass hierarchy using a reactor neutrino experiment at $\sim$60 km is analyzed. Such a measurement is challenging due to the finite detector resolution, the absolute energy scale calibration, as well as the degeneracies caused by current experimental uncertainty of $|\Delta m^2_{32}|$. The standard $\chi^2$ method is compared with a proposed Fourier transformation method. In addition, we show that for such a measurement to succeed, one must understand the non-linearity of the detector energy scale at the level of a few tenths of percent.