The CERN implementation of the ENUBET/nuSCOPE beamline

Neutrino physics has entered an era of precision measurements, driven by the goal of resolving fundamental questions such as the existence of CP violation in the lepton sector, the neutrino mass ordering, and the precise values of oscillation parameters. Next-generation long-baseline experiments, namely the Deep Underground Neutrino Experiment (DUNE) and HyperKamiokande, are set to address these questions with unprecedented statistical power. However, their ultimate sensitivity will be constrained by systematic uncertainties, which are currently dominated by an incomplete understanding of neutrino-nucleus interaction cross-sections in the intermediate energy range. Reducing these uncertainties from the current 10-20% level to the percent level is therefore key to reaching ultimate precision for the future neutrino oscillation program.

This thesis presents a comprehensive design study for the nuSCOPE (Neutrino SPS COmplex for Precision Experiments) facility, a next-generation short-baseline experiment conceived to address this challenge. nuSCOPE is based on the novel concept of a monitored and tagged neutrino beam, capable of providing a measurement of the neutrino flux with an accuracy of $\sim1\%$, an order of magnitude improvement over existing facilities. Such precision will enable high-resolution measurements of absolute neutrino cross-sections, providing essential data to tune and validate the interaction models used by DUNE and HyperKamiokande.

The work detailed in this thesis is based on a complete, end-to-end design of the nuSCOPE beamline, optimized for implementation at the CERN Super Proton Synchrotron (SPS) by CERN in the framework of Physics Beyond Collider. The proposed facility utilizes a 400 GeV slow-extracted proton beam impinging on a graphite target to produce a narrow-band beam of $K^+$ and $\pi^+$ mesons with a central momentum of 8.5 GeV and a momentum spread of 10 %. The beamline optics, comprising a static focusing system of quadrupole and dipole magnets, was optimized using a multi-objective genetic algorithm to maximize the meson yield while ensuring the beam remains parallel through a 40-meter-long instrumented decay tunnel. This thesis presents the detailed configuration of all key components, including the target, a novel collimator design, the magnetic transfer line, and the hadron dump, with a proposed implementation in the existing TT61 tunnel at CERN.

The feasibility and robustness of the proposed design were validated through extensive Monte Carlo simulations using the FLUKA code. Two critical aspects were investigated in depth: thermal effects on beamline components and the radiological assessment of the facility.
The thermal analysis shows that the highest energy deposition occurs in the graphite target, leading to a peak temperature increase of approximately 402 K per beam pulse. A subsequent analysis of the induced thermo-mechanical stresses confirms that the peak Von Mises stress of 12.2 MPa remains well within the structural limits of graphite, ensuring the target's integrity. The temperature rise in other components, such as the copper collimator ($\sim$ 16 K), is modest, eliminating the need for complex active cooling systems.

The radiation protection study demonstrates the effectiveness of the proposed shielding, composed of cast iron and concrete. Prompt dose rate simulations confirm that the shielding is sufficient to allow for emergency access to the experimental tunnel during operation. The analysis of residual dose rates provides information for planning maintenance and intervention scenarios, identifying radiological hotspots while confirming that most areas become accessible after short cooling periods. A particular focus was placed on potential radiation damage of the silicon pixel trackers, which are essential for the neutrino tagging technique. The studies show that the total dose and the 1-MeV-neutron-equivalent fluence on the most exposed tracker are within the operational limits of current and proposed radiation-hard technologies.

In conclusion, this thesis delivers a complete and self-consistent design for the nuSCOPE facility. The detailed studies confirm that the proposed beamline is technically feasible, radiologically safe, and capable of meeting the demanding performance requirements for a new generation of precision neutrino cross-section measurements.