Resolving the mass hierarchy with atmospheric neutrinos using a liquid argon detector

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), (nu)overbar(mu) and, over a limited energy range, to nu(e), (nu)overbar(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)>= 0.05. For an unmagnetized detector, a 2.5 sigma hierarchy sensitivity is possible for sin(2)2 theta(13)=0.04.