Resolving the Mass Hierarchy with Atmospheric Neutrinos using a Liquid Argon Detector

TL;DR

This paper investigates how large liquid argon detectors can determine the neutrino mass hierarchy using atmospheric neutrino interactions, showing significant sensitivity improvements over existing methods.

Contribution

It demonstrates the potential of large-mass liquid argon detectors, both magnetized and unmagnetized, for resolving the neutrino mass hierarchy with high statistical significance.

Findings

> 4σ hierarchy resolution for heta_{13} extgreater 0.05 over 10 years

2.5σ sensitivity for unmagnetized detector at heta_{13} = 0.04

Superior capabilities compared to previous neutrino detection methods

Abstract

We explore the potential offered by large-mass Liquid Argon detectors for determination of the sign of Delta m_{31}^2, or the neutrino mass hierarchy, through interactions of atmospheric neutrinos. We give results for a 100 kT sized magnetized detector which provides separate sensitivity to \nu_\mu, \bar{\nu}_\mu and, over a limited energy range, to \nu_e, \bar{\nu}_e.We also discuss the sensitivity for the unmagnetized version of such a detector. After including the effect of smearing in neutrino energy and direction and incorporating the relevant statistical,theoretical and systematic errors, we perform a binned \chi^2 analysis of simulated data. The \chi^2 is marginalized over the presently allowed ranges of neutrino parameters and determined as a function of \theta_{13}. We find that such a detector offers superior capabilities for hierarchy resolution, allowing a > 4\sigma determination for a 100 kT detector over a 10 year running period for values of \sin^2 2\theta_{13} \ge 0.05. For an unmagnetized detector, a 2.5\sigma hierarchy sensitivity is possible for \sin^2 2\theta_{13} = 0.04.