The ESS Based Neutrino Super Beam for CP Violation Discovery

AbstractAfter measuring the last neutrino mixing angle θ13 and finding it relatively large, the observation of CP violation in the leptonic sector is now reachable with the condition to have significantly more intense neutrino beams than the existing ones. For this θ13 value, it came out that going to the second oscillation maximum instead of the first one, provides more sensitivity to CP violation. The European Spallation Source facility in Lund, designed to accelerate protons to 2.0GeV at a repetition rate of 14Hz for neutron production, could also be used to produce a copious number of neutrinos. Doubling the frequency of its proton linac opens the possibility to operate the facility simultaneously for neutron and neutrino production. An accumulator ring would be needed to shorten the pulses from 2.86ms for neutrons to few μs in order to reduce to acceptable levels the electric current sent to the magnetic horn focusing charged mesons to acceptable levels for the neutrino production. This accumulator could also be used by the neutron facility to increase its performance. Coupled with a megaton Water Cherenkov far detector placed at the optimal distance, this facility could efficiently exploite the second oscillation maximum to cover a large fraction of the CP violation parameter δCP at 5 σ confidence level