Two methods are employed to measure the neutrino flux of the antineutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high-purity ${\nu }_{\mu }$-induced charged-current single ${\pi }^{+}$ ($\mathrm{CC}1{\pi }^{+}$) sample while the second exploits the difference between the angular distributions of muons created in ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ charged-current quasielastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the predominately antineutrino beam is overestimated—the $\mathrm{CC}1{\pi }^{+}$ analysis indicates the predicted ${\nu }_{\mu }$ flux should be scaled by $0.76\pm 0.11$, while the CCQE angular fit yields $0.65\pm 0.23$. The energy spectrum of the flux prediction is checked by repeating the analyses in bins of reconstructed neutrino energy, and the results show that the spectral shape is well-modeled. These analyses are a demonstration of techniques for measuring the neutrino contamination of antineutrino beams observed by future nonmagnetized detectors.

• Received 20 March 2011

DOI:https://doi.org/10.1103/PhysRevD.84.072005