Measuring Antineutrino Oscillations in MINOS

MINOS previously reported the first results of $\bar{\nu}_{\mu}$ disappearance from a direct observation of accelerator based muon antineutrinos in a long baseline experiment. The 7\% antineutrino component of the NuMI beam was used and a high purity sample of antineutrinos was selected at both the Near and Far Detectors. Selection efficiency at the Far Detector was 83\% and the purity of the selected $\bar{\nu}_{\mu}$ CC sample was 97\%. With this sample MINOS exludes a previously allowed CPT violating region of $\Delta\bar{m}^{2}_{atm}$ at maximal mixing and constrains the fraction of $\nu_{\mu}$ that disappear and reappear as $\bar{\nu}_{\mu}$. We present new measurements of $\bar{\nu}_{\mu}$ oscillation parameters and of the $\nu_{\mu} \rightarrow \bar{\nu}_{\mu}$ transition probability using the muon antineutrino spectra based on a larger data sample.