2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/214713An optimization of the CERN SPL beam line has been performed guided by the sensitivities to the θ_{13} mixing angle and to the δ_{CP} Dirac CP violating phase. A UNO-like 440 ktons water Cerenkov detector located at 130 km from the target in a new foreseen Frejus laboratory has been used as a generic detector. Concerning the δ_{CP} independent θ_{13} sensitivity, a gain of about 20% may be reached using a 3.5 GeV proton beam with a 40 m long, 2 m radius decay tunnel compared to the up to now considered 2.2 GeV beam energy and 20 m long, 1 m radius decay tunnel. This may motivate new machine developments to upgrade the nominal SPL proton beam energy.17 pages, 19 figures, submitted to European Physical Journal CHigh Energy Physics - Experimenttext