Beamline design and calorimeter prototypes for the ENUBET monitored neutrino beam facility

The goal of the ENUBET (Enhanced NeUtrino BEams from Kaon Tagging) ERC project is to develop the first "monitored neutrino beam", where the neutrino flux can be measured with a 1% precision. The idea is to fully instrument the secondary particle decay tunnel with a longitudinally segmented calorimeter, which will tag the leptons produced together with the neutrinos (tagger). This thesis focuses on two aspects: the design of the hadronic beamline and the development of the tagger instrumentation technology. Regarding the beamline design, a GEANT4 simulation of the facility is presented, together with its strenghts and the implementation details (magnetic elements, collimators). Special focus is given to the optimization strategy of the various elements, thanks to an optimization procedure based on a genetic algorithm, that allowed to increase the signal-to-noise ratio in the decay tunnel. The hardware work on the tagging calorimeter was carried out at the INFN Legnaro National Laboratories, where a prototype (ENUBINO) was assembled and tested. Enubino is a calorimeter that features the final design for the ENUBET Demonstrator of the tagger, and was tested on a charged particle beam at CERN PS. The details of the construcion of Enubino (and the advancements on the Demonstrator building) are presented together with analysis of the collected data during the test beam. Thanks to these studies, the design of the beamline and of the tagger instrumentation technology have been finalized, and will be used for the future implementation of ENUBET.