Resonant oscillations of atmospheric neutrinos with an underground muon detector

We have reanalyzed the sensitivity of an underground muon detector to (${\nu }_{\mu }$⇆${\nu }_e$) oscillations, taking into account the Wolfenstein, Mikheyev, and Smirnov matter effect. We find that the measurement of the charge of the muons would greatly improve the sensitivity of this type of experiment. Such a measurement would enhance the statistical significance of an eventual oscillation signal and, allowing for a comparison of the ${\mu }^{\mathrm{-}}$ and ${\mu }^{+}$ fluxes, can eliminate the systematic uncertainty upon the absolute normalization of the neutrino flux. We show that a realistic detection system can explore the region in parameter space 3×${10}^{\mathrm{-}3}$≤Δ$m^2$≤${10}^{\mathrm{-}1}$ ${\mathrm{eV}}^2$ and ${\sin }^2$2θ≥0.02, which is well below current accelerator and reactor limits.