Optimization of a neutrino factory oscillation experiment

Abstract

We discuss the optimization of a neutrino factory experiment for neutrino oscillation physics in terms of muon energy, baselines, and oscillation channels (gold, silver, platinum). In addition, we study the impact and requirements for detector technology improvements, and we compare the results to beta beams. We find that the optimized neutrino factory has two baselines, one at about 3000 to 5000 km, the other at about 7500 km ("magic" baseline). The threshold and energy resolution of the golden channel detector have the most promising optimization potential. This, in turn, could be used to lower the muon energy from about 50 GeV to about 20 GeV. Furthermore, the inclusion of electron neutrino appearance with charge identification (platinum channel) could help for large values of sin22theta13. Though tau neutrino appearance with charge identification (silver channel) helps, in principle, to resolve degeneracies for intermediate sin22theta13, we find that alternative strategies may be more feasible in this parameter range. As far as matter density uncertainties are concerned, we demonstrate that their impact can be reduced by the combination of different baselines and channels. Finally, in comparison to beta beams and other alternative technologies, we clearly can establish a superior performance for a neutrino factory in the case sin22theta13<~0.01

Determining neutrino and supernova parameters with a galactic supernova

“…In the case that only the main channel is available (IB or ν e CC) a degeneracy in θ 13 and the hierarchy occurs and θ 13 cannot be determined (unless the hierarchy has already been established by another experiment). If sin 2 θ 13 turns out to be in the region where P H ≃ 1, then there is no possibility that it can be determined by any of the laboratory experiments currently proposed [53,54,55,56]. In this case SN information will be extremely valuable.…”

“…So to reach sensitivities to sin 2 θ 13 < ∼ 10 −3 before a new galactic SN observation one would probably need beta-beams [55] or neutrino factories [56]. Correspondingly, the determination of a lower bound on θ 13 of order 10 −4 from a SN observation for the cases i0 and n0, can be of great importance.…”

Interim Design Report

“…The results shown in figure 7 have been used to optimise the facility for the largest possible reach in sin 2 2θ 13 , in other words, for the small sin 2 2θ 13 case. The optimum discovery reach in sin 2 2θ 13 is for the L and E µ combinations in the white regions of the plots; for details, see reference [107]. The excellent sensitivity to sin 2 2θ 13 at about 7 500 km can be easily understood in terms of the magic baseline [105,113].…”

“…For a more detailed discussion of these possible optimisation strategies see reference [100]. The optimisation of the Neutrino Factory has been studied in great detail, for instance, in references [101][102][103][104][105][106][107][108][109][110]. Here we will give a brief summary of the considerations which led to the IDS-NF baseline setup.…”

“…The oscillation maximum is at relatively low energies in the Neutrino Factory spectrum, therefore a low energy threshold, has been identified as the main priority for the optimisation of the Magnetised Iron Emulsion Detector (MIND) [107]. The low energy threshold provided by the MIND (see section 3) allows for a reduction of E µ to values as low as about ∼ 20 GeV without significant loss of sensitivity [107]. Therefore, the IDS-NF baseline setup with a MIND detector uses E µ = 25 GeV.…”