The contamination from ν ̄e in the T2K antineutrino beam is predicted to be approximately 1% and needs to be evaluated in order to constrain the systematic uncertainties in a T2K antineutrino oscillation measurement. In this thesis we present a ν ̄e charged-current selection with which we test the Monte Carlo predic- tion using T2K data. To select ν ̄e charged-current events, the tracker region and electromagnetic calorimeters of the T2K off-axis near detector are used.
The selected sample has a ν ̄e purity of (41.9±2.4)% and an efficiency of (27.1± 1.7)%. The data to Monte Carlo ratio for ν ̄e charged-current inclusive interactions is 1.07 ± 0.16(stat.) ± 0.13(syst.).