Optimal β-beam at the CERN-SPS Original Research Article

A β-beam with maximum image (for 6He ions) or image (for 18Ne) could be achieved at the CERN-SPS. We study the sensitivity to image and δ of such a beam as function of γ, optimizing with the baseline constrained to CERN–Frejus (130 km), and also with simultaneous variation of the baseline, for a fixed ion flux. These results are compared to the standard scenario previously considered, with lower image, and also with a higher image option that requires a more powerful accelerator. We conclude that the sensitivity to CP violation and image increases significantly with γ if the baseline is increased proportionally, while for the CERN–Frejus scenario the dependence on γ is mild provided γ is above 100.