Published online by Cambridge University Press: 14 August 2015
Secondary antiprotons are a potentially interesting probe of cosmic ray propagation because their production cross section is strongly energy-dependent, increasing by more than two orders of magnitude between 10 and 1000 GeV/c. This is quite unlike the case for fragmentation cross sections of complex nuclei, which are virtually constant with energy. Moreover, the flux depends primarily on the environment seen by protons which need not be identical to that probed by other nuclei.