Monitored neutrino beams: NP06/ENUBET

The main source of systematic uncertainty on neutrino cross section measurements at the GeV scale is represented by the poor knowledge of the initial flux. The goal of cutting down this uncertainty to 1% can be achieved through the monitoring of charged leptons produced in association with neutrinos, by properly instrumenting the decay region of a conventional narrow-band neutrino beam. The ENUBET project has been funded by the ERC in 2016 to prove the feasibility of such a monitored neutrino beam and is cast in the framework of the CERN Neutrino Platform (NP06) and the Physics Beyond Colliders initiative. This contribution reports the final design of the horn-less beamline able to deliver a meson yield large enough to perform a ve cross section measurement at 1% precision in about 3 years of data taking at CERN-SPS with a ProtoDUNE-like detector. The final configuration of the tunnel instrumentation and its implementation on a large-scale prototype, the Demonstrator, are also described. Finally the particle identification performance is presented together with the first assessment of the lepton monitoring impact in the reduction of the hadroproduction systematics on the neutrino flux.