Optimal $\beta$-beam at the CERN-SPS

In this talk, based on the work [J. Burguet-Castell et al., Nucl. Phys. B 725 (2005) 306], we present an analysis of the sensitivity to the mixing angle θ13 and the CP-violating phase δ that could be achieved by a β-beam experiment based at the SPS accelerator at CERN. We estimate the optimal γ boost of the 6He and 18Ne ions for the proposed baseline CERN-Frèjus (130 km), and also perform a simultaneous optimization of the ion boost and the baseline. A possible improvement of the current SPS accelerator is considered as well. After comparing the sensitivities of all relevant setups, we conclude that a β-beam running at the maximum acceleration achievable by the SPS, γ=150/250, and with a baseline of L≈300 km, could reach a sensitivity to θ13 and leptonic CP-violation which is significantly greater to that obtainable with the baseline L=130 km (CERN to Frèjus).