Neutrino oscillations at an entry-level neutrino factory and beyond

We consider the parameters of an entry-level neutrino factory designed to make the first observation of ν_e→ν_μ oscillations, measure the corresponding amplitude sin²2θ₁₃, and determine the sign of the atmospheric-scale δm₃₂² via matter effects. A 50 kt detector, a stored muon energy E_μ>~20 GeV and 10¹⁹ muon decays would enable these goals to be met provided sin²2θ₁₃>0.01. The determination of the sign of δm₃₂² also requires a baseline L>~2000 km. An upgraded neutrino factory with O(10²⁰) decays would enable the first observation of ν_e→ν_τ oscillations. With O(10²¹) decays the effects of a large CP phase could be measured in the case of the large angle matter oscillation solution to the solar neutrino anomaly. Our analysis includes a family of three-neutrino models that can account for the atmospheric and solar neutrino oscillation indications.