Direct detection of Earth matter effects (MSW) in flavor oscillations at neutrino beams from stored muon decays

We explore the possibility of a neutrino oscillation experiment with a very long baseline in the range of $6500\ \rm km$ and a neutrino beam produced by the decays of muons circulating in a storage ring. The recent developments in view of muon colliders allow us to envisage neutrino sources of a sufficiently high intensity. We first consider $\nue\leftrightarrow\numu$ oscillations within a three flavor oscillation framework. Evidence for this oscillation implies that the (1-3) mixing is non-zero. We study the effect of the neutrino propagation through matter (MSW effect). Given the density of the Earth, the existence of the MSW resonance can be experimentally proven by comparing the oscillated spectra of neutrinos obtained from the decays of muons of positive and negative charges. Moreover, a precision study of the oscillations of all three flavors could be performed since neutrinos are above the tau production threshold (appearance searches).