A new calculation of the interstellar secondary cosmic-ray antiprotons

We present new results for the theoretical prediction of the interstellar secondary antiproton flux produced in cosmic ray interactions with the interstellar gas. The calculation is performed in the framework of the standard leaky box model (LBM). In comparison to earlier calculations, we believe we have reached improvements in three aspects. We use the proton and helium spectra, as recently measured by the IMAX instrument, and the Monte Carlo model DTUNUC to study the contributions to the (p) over bar flux from p-nucleus, nucleus-p and nucleus-nucleus collisions, and we allow for energy-changing processes caused by the nonannihilation process and by elastic scattering. We compare the results for the (p) over bar flux with earlier calculations and with recently published data. We illustrate that the path length distribution (PLD) remains the dominant source of uncertainty. We also point out another source of uncertainty, the attempt to iind a proper fit to measured (p) over bar-production cross sections from p-p interactions. Published parameterizations differ and cause an uncertainty in the predicted (p) over bar flux of almost 40%. We show that within these uncertainties, recently published data on the (p) over bar flux are in agreement with the assumption that the observed antiprotons are of secondary origin.