[en] The knockout of protons from ⁸B and ⁹C on a carbon target has been studied at average energies of 76 and 78 MeV/nucleon, respectively, with beams from the A1900 fragment separator incident on a stack of silicon detectors. The following cross sections were obtained: σ_-1p(⁸B→⁷Be)=130(11) mb, σ_-1p(⁹C→⁸B)=54(4) mb, and σ_-2p(⁹C→⁷Be)=98(7) mb. The results are discussed within the framework of an eikonal approach and compared with measurements performed at higher energies. From this analysis, a consistent picture emerges that gives evidence for the validity of the eikonal approach at energies below 100 MeV/nucleon. Knockout reactions at intermediate energy can thus be used to deduce absolute shell occupancies. We find the spectroscopic factors to be reduced by R_s of 0.86(7) and 0.82(6) for ⁸B and ⁹C, respectively, relative to shell-model predictions. The ⁹C result provides an accurate measurement of the asymptotic normalization coefficient of 1.27(10) fm^-1. A new technique is reported for determining separately the contributions from stripping and diffractive breakup

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