The P42 beamline transports 400 GeV protons from the CERN SPS between the T4 and T10 targets. A secondary particle beam is produced at the T10 target and transported along the K12 beamline to the experimental cavern ECN3, presently housing the NA62 experiment. In the context of the Physics Beyond Colliders (PBC) study, an increase of the beam intensity in P42 has been considered to provide protons to a future high-intensity fixed-target experiment in ECN3. For both its present usage and especially for the intensity upgrade, it is important to reduce beam losses to a minimum to decrease environmental radiation levels and protect equipment. In this study, simulations of P42 with the Monte Carlo software BDSIM, are used to demonstrate that beam losses in P42 are primarily driven by particle-matter interactions in material intercepted by the beam. The distribution of the simulated losses is compared to doses measured along the beamline in radioprotection surveys and beam loss monitors. Future mitigation strategies to reduce beam losses are then discussed and evaluated.

During the operation of a muon collider in an underground tunnel, most circulating muons decay into an electron (or positron) and a neutrino-antineutrino pair, resulting in a narrow disk of high-energy neutrinos emitted radially in the collider plane and emerging on the Earth’s surface at distances of several km. Thus, dedicated studies are required to assess any potential radiation protection risks to the public due to the interaction of such neutrinos near the surface. This work presents a set of FLUKA Monte Carlo simulations aimed at characterizing the radiation showers generated by the interactions of high-energy neutrinos from TeV-scale muon decays in a reference sample of soil. The results are expressed in terms of effective dose in soil at different distances from the muon decay, quantifying the peak dose and the width of the radiation cone, for beam energies of 1.5 TeV and 5 TeV. The implications of these results for realistic muon collider scenarios are discussed, along with possible methods to mitigate the local neutrino flux.

Muon production in the multi-TeV muon collider studied by the International Muon Collider Collaboration is planned to be performed with a high-power proton beam interacting with a fixed target. The design of the target area comes with a set of challenges related to the radiation load to front-end equipment. The confinement of the emerging pions and muons requires very strong magnetic fields achievable only by superconducting solenoids, which are sensitive to heat load and long-term radiation damage. The latter concerns the ionizing dose in insulation, as well as the displacement damage in the superconductor. The magnet shielding design has to limit the heat deposition and ensure that the induced radiation damage is compatible with the operational lifetime of the muon production complex. Finally, the fraction of the primary beam passing through the target unimpeded poses a need for an extraction channel. In this study, we use the FLUKA Monte Carlo code to assess the radiation load to the solenoids, and we explore the possible spent proton beam extraction scenarios taking into account the constraints stemming from the beam characteristics and the required magnetic field strength.