A Monochromatic Neutrino Beam for U(e3) and CP-Phase

The goal for future neutrino facilities is the determination of the $[U_{e3}]$ mixing and CP violation in neutrino oscillations. This will require precision experiments with a very intense neutrino source. Here a novel method to create a monochromatic neutrino beam based on the recent discovery of nuclei that decay fast through electron capture is discussed. The boost of such radioactive ions will generate a monochromatic directional neutrino beam when decaying at high energy in a storage ring with long straight sections. We show that the capacity of such a facility to discover new physics is impressive, so that the principle of energy dependence in the oscillation probability of the $\nu_e \to \nu_{\mu}$ channel is operational to separate out the two parameters of the mixing $\theta_{13}$ and of the CP-violating phase $\delta$.