Propagation of injected cosmic rays under distributed reacceleration

The cosmic ray acceleration model in which the particles gain continuously energy from stochastic processes in the interstellar space by encountering shocks leads to a logarithmic increase in the secondary to primary ratios with energy, which is inconsistent with observations. The observed decrease of the secondary to primary ratios may therefore suggest that a considerable part of the acceleration has taken place rapidly at the sources. Astronomical observations on the other hand indicate that shocks from supernovae do exist in the galaxy and observations in the interplanetary space show clear evidence that shock acceleration works.