Measuring Antineutrino Disappearance at MINOS using a NuMI Antineutrino Beam

The NuMI beam-line was recently reconfigured to produce a primarily $\bar\nu_\mu$-beam by reversing the current in its two focusing horns. With an exposure $1 \times 10^{20}$ protons-on-target we can measure $\Delta\bar{m}_{23}^{2}$ to a precision of $25\%$ at maximal mixing at $90\%$ confidence, more than a factor of 3 improvement over current combined world limits. It is also a significant improvement on MINOS' own measurement of $\bar\nu_\mu$ oscillation parameters using the small $\bar\nu_\mu$ component of the primarily $\nu_\mu$ beam. The measurement will take advantage of MINOS' two magnetized steel-scintillator detectors and their unique ability to distinguish positive and negative muons and thus separate charged current neutrino and antineutrino interactions event-by-event.