Determination of the pattern of neutrino masses at a Neutrino Factory

Abstract

We study the precision to which the sign of δm_{32}^2 can be determined at a neutrino factory, as a function of stored energies and baselines. This is done by simultaneously fitting the channels ν_μ\to ν_μ$, \barν_e \to \barν_μfrom μ^- decays and the channels \barν_μ\to \barν_μ, ν_e \to ν_μfrom μ^+ decays. We investigate the sensitivity reach in the parameter \sin^22θ_{13} to which one can determine the sign of δm_{32}^2 to 3 standard deviations as a function of the baseline length and magnitude of δm_{32}^2 with a 20 GeV muon storage ring. We find that for baselines longer than 2000 km, the sign of δm^2_{32} can be determined for \sin^22θ_{13} down to the 10^{-3} level with 10^{20} decays of 20 GeV muons.