Optimization of the baseline and the parent muon energy for a low energy neutrino factory

Abstract

We discuss the optimal setup for a low energy neutrino factory in order to achieve a 5σ discovery of a nonzero mixing angle θ₁₃, a nonzero CP phase δ_CP, and the mass hierarchy. We explore parent muon energies in the range 5–16 GeV, and baselines in the range 500–5000 km. We present the results in terms of the reach in sin²θ₁₃, emphasizing the dependence of the optimal baseline on the true value of δ_CP. We show that the sensitivity of a given setup typically increases with parent muon energy, reaching saturation for higher energies. The saturation energy is larger for longer baselines; we present an estimate of this dependence. In the light of the recent indications of a large θ₁₃, we also determine how these preferences would change if indeed a large θ₁₃ is confirmed. In such a case, the baselines ~2500 km (~1500 km) may be expected to lead to hierarchy determination (δ_CP discovery) with the minimum exposure.