[en] The longitudinal momentum distribution of ⁷Be fragments after fragmentation of ⁸B and the one-proton removal cross section (σ_-1p) in a carbon target were measured at 1440 MeV/u with the fragment separator FRS used as an energy-loss spectrometer. The results show a narrow momentum distribution with a FWHM value of 91±5 MeV/c and a large cross-section, σ_-1p=98±6 mb. Both these results support the interpretation of a spatially extended proton orbit forming a halo in the ⁸B ground state. The momentum distribution and the one-proton removal cross section are shown to be reproduced with a three-body wave function for ⁸B where the target is treated as a black disc in the breakup process. (orig.)