Counting Electrons to Probe the Neutrino Mass Hierarchy

After the successful measurement of the mixing angle $\theta_{13}$, the determination of the neutrino mass hierarchy has become a priority for future neutrino experiments. We propose a conventional $\nu_\mu$ beam with neutrino energies in the range 2-8 GeV aimed at a Mton underwater detector at the "magic" baseline of 2600 km. In this constellation it is sufficient to distinguish ($\nu_\mu$ induced) track-like interactions from cascade-like interactions with moderate purity to determine the mass hierarchy.