Improvement of the low energy neutrino factory

Abstract

The low energy neutrino factory has been proposed as a very sensitive setup for future searches for $CP$ violation and matter effects. Here we study how its performance is affected when the experimental specifications of the setup are varied. Most notably, we have considered the addition of the ``platinum'' ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e}$ channel. We find that, while theoretically the extra channel provides very useful complementary information and helps to lift degeneracies, its practical usefulness is lost when considering realistic background levels. Conversely, an increase in statistics in the ``golden'' ${\ensuremath{\nu}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ channel and, to some extent, an improvement in the energy resolution, lead to an important increase in the performance of the facility, given the rich energy dependence of the ``golden'' channel at these energies. We show that a low energy neutrino factory with a baseline of 1300 km, muon energy of 4.5 GeV, and either a 20 kton totally active scintillating detector or 100 kton liquid argon detector, can have outstanding sensitivity to the neutrino oscillation parameters ${\ensuremath{\theta}}_{13}$, $\ensuremath{\delta}$, and the mass hierarchy. For our estimated exposure of $2.8\ifmmode\times\else\texttimes\fi{}{10}^{23}\text{ }\text{ }\mathrm{kton}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{decays per muon polarity}}$, the low energy neutrino factory has sensitivity to ${\ensuremath{\theta}}_{13}$ and $\ensuremath{\delta}$ for ${sin}^{2}(2{\ensuremath{\theta}}_{13})>{10}^{\ensuremath{-}4}$ and to the mass hierarchy for ${sin}^{2}(2{\ensuremath{\theta}}_{13})>{10}^{\ensuremath{-}3}$.