The ERC ENUBET Project: high precision neutrino flux measurements in conventional neutrino beams

The challenges of precision neutrino physics require measurements of absolute neutrino cross sections at the GeV scale with exquisite (1%) precision. This precision is presently limited by the uncertainties on neutrino flux at the source; their reduction by one order of magnitude can be achieved monitoring the positron production in the decay tunnel originating from the $K_{e3}$ decays of charged kaons in a sign and momentum selected narrow band beam. This novel technique enables the measurement of the most relevant cross sections for CP violation ($\nu_e$ and $\overline{\nu}_e$) with a precision of 1% and requires a special instrumented beam-line. Such non-conventional beam-line will be developed in the framework of the ENUBET Horizon-2020 Consolidator Grant, recently approved by the European Research Council. The project, the first experimental results on ultra-compact calorimeters that can be embedded in the instrumented decay tunnel and the advances on the simulation of the beamline are presented. We also discuss the detector and accelerator activities that are planned in 2016-2021.