The EUROnu Project

TL;DR

The EUROnu project evaluated three future neutrino oscillation facilities in Europe—Super Beam, Neutrino Factory, and Beta Beam—assessing their design, performance, and potential for measuring CP violation, with the Neutrino Factory emerging as the most promising option.

Contribution

The paper provides the first comprehensive conceptual designs and performance studies of three advanced neutrino facilities in Europe, comparing their physics reach and costs.

Findings

Neutrino Factory offers the best physics potential for CP violation measurement.

Super Beam is a cost-effective alternative if a powerful proton driver is available.

All facilities have distinct advantages depending on future infrastructure developments.

Abstract

The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Fr\'ejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of {\mu}+ and {\mu}- beams in a storage ring. The far detector in this case is a 100 kt Magnetised Iron Neutrino Detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular 6He and 18Ne, also stored in a ring. The far detector is also the MEMPHYS detector in the Fr\'ejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.