THE Theta_ 13 AND Delta_ CP Sensitivities of the SPS-Fréjus preject revisited

An optimization of the CERN SPL beam line has been performed guided by the sensitivities to the θâ'13 mixing angle and to the δCP Dirac CP violating phase. A UNOlike 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 δCP independent θâ'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.