High energy beta beams without massive detectors

Abstract

In this paper, the possibility to exploit a high energy beta beam without massive detectors is discussed. The radioactive ions are boosted up to very high $γ$ with the neutrino beam pointing towards an instrumented surface located at a moderate baseline (e.g. from CERN to the Gran Sasso Laboratories). $ν_e \to ν_μ$ oscillations and their CP conjugate are tagged as an excess of horizontal muons produced in the rock and tracked by the low-mass instrumented surface installed in one of the LNGS experimental halls. We show that the performance of this complex for what concerns the determination of the $θ_{13}$ angle of the leptonic mixing matrix is comparable with the current low-$γ$ design based on a gigantic water Cherenkov at Frejus.