  The AMS-02 experiment is measuring the cosmic ray antiproton flux with high
precision. The interpretation of the upcoming data requires a thorough
understanding of the secondary antiproton background. In this work, we employ
newly available data of the NA49 experiment at CERN, in order to recalculate
the antiproton source term arising from cosmic ray spallations on the
interstellar matter. We systematically account for the production of
antiprotons via hyperon decay and discuss the possible impact of isospin
effects on antineutron production. A detailed comparison of our calculation
with the existing literature as well as with Monte Carlo based evaluations of
the antiproton source term is provided. Our most important result is an updated
prediction for the secondary antiproton flux which includes a realistic
assessment of the particle physics uncertainties at all energies.
