A low energy neutrino factory with non-magnetic detectors

TL;DR

This paper demonstrates that non-magnetic detectors like water Cherenkov or liquid Argon can effectively contribute to low energy neutrino factory experiments by utilizing oscillation-enhanced signal-to-noise ratios and partial neutrino/anti-neutrino separation.

Contribution

It shows that precise neutrino/anti-neutrino separation is not essential, enabling the use of large, non-magnetic detectors for CP violation and mass hierarchy studies in neutrino factories.

Findings

Non-magnetic detectors can achieve 50-90% neutrino/anti-neutrino separation.

Oscillation enhances wrong sign muon detection without magnetic fields.

Large non-magnetic detectors can effectively explore CP violation and mass hierarchy.

Abstract

We show that a very precise neutrino/anti-neutrino event separation is not mandatory to cover the physics program of a low energy neutrino factory and thus non-magnetized detectors like water Cerenkov or liquid Argon detectors can be used. We point out, that oscillation itself strongly enhances the signal to noise ratio of a wrong sign muon search, provided there is sufficiently accurate neutrino energy reconstruction. Further, we argue that apart from a magnetic field, other means to distinguish neutrino from anti-neutrino events (at least statistically) can be explored. Combined with the fact that non-magnetic detectors potentially can be made very big, we show that modest neutrino/anti-neutrino separations at the level of 50% to 90% are sufficient to obtain good sensitivity to CP violation and the neutrino mass hierarchy for $\sin^22\theta_{13}>10^{-3}$. These non-magnetized detectors have a rich physics program outside the context of a neutrino factory, including topics like supernova neutrinos and proton decay. Hence, our observation opens the possibility to use a multi-purpose detector also in a neutrino factory beam.