Neutrino factories and the "magic" baseline

We show that for a neutrino factory baseline of Lsimilar to7 300-7 600 km a "clean" measurement of sin(2)2theta(13) becomes possible, which is almost unaffected by parameter degeneracies. We call this baseline the "magic" baseline, because its length depends only on the matter density profile. For a complete analysis, we demonstrate that the combination of the magic baseline with a baseline of 3 000 km is the ideal solution to perform equally well for sin(2)2theta(13), the sign of Deltam(31)(2), and CP violation sensitivities. In particular, this combination can very successfully resolve parameter degeneracies even below sin(2)2theta(13)<10(-4).