Intense Neutrino Beams and Leptonic CP Violation

Effects of the Leptonic CP violating phase,\delta, on 3 generation neutrino oscillation rates and asymmetries are discussed. A figure of merit argument is used to show that our ability to measure the phase \delta is rather insensitive to the value of \theta_{13} (for \sin^22\theta_{13}\gsim0.01) as well as the detector distance (for very long oscillation baselines). Using a study of \nu_\mu\to\nu_e oscillations for BNL-Homestake (2540 km) we show that a conventional horn focused wide band neutrino beam generated by an intense 1-2 MW proton source combined with a very large water Cherenkov detector (250-500 kton) should be able to determine \delta to about \pm 15^\circ$ in 5\times 10^7sec of running. In addition, such an effort would also measure the other oscillation parameters (\theta_{ij},\Delta m^2_{ij}) with high precision. Similar findings apply to a Fermilab-Homestake (1280 km)baseline. We also briefly discuss features of Superbeams, Neutrino Factories and Beta-Beams.