We present the results of a study of the inclusive reaction $\overline{\nu }p\to {\mu }^{+}{X}^0$ for antineutrino energies from 5 to 150 GeV. The data were obtained by exposing the Fermi National Accelerator Laboratory hydrogen-filled 15-foot bubble chamber to a wide-band antineutrino beam. This is the first high-energy antineutrino experiment in which a pure proton target was used. The experimental problems of selecting the required sample of charged-current antineutrino-induced events are discussed in detail. A Monte Carlo simulation of the experiment is used to provide correction factors to the measured distributions. A measurement of the $x$ dependence of the inelasticity ($y$) distributions gives the proton structure functions $F_2^{\overline{\nu }p}\mathrm{}\left(x\right)\mathrm{}$ and $x{F}_3^{\overline{\nu }p}\mathrm{}\left(x\right)\mathrm{}$ up to an overall normalization constant. When expressed in terms of the quark-parton model, the quark distributions $u\mathrm{}\left(x\right)\mathrm{}$ and $\overline{d}\mathrm{}\left(x\right)+\overline{s}\mathrm{}\left(x\right)\mathrm{}$ are determined. The results for $u\mathrm{}\left(x\right)\mathrm{}$ are found to be in excellent agreement with models based on fits to electron and muon scattering data. Using these results to fix the $u\mathrm{}\left(x\right)\mathrm{}$ normalization, an absolute measurement is made of $x\left[\overline{d}\mathrm{}\right(x)+\overline{s}\mathrm{}(x\left)\right]$, the antiquark momentum distribution.

• Received 19 June 1981

DOI:https://doi.org/10.1103/PhysRevD.25.1