Time dispersion of energetic solar particles, unexpected velocity and species dependence

The intensity--time behavior for protons and helium, as well as for carbon, oxygen, and iron ions, was measured following the 1974 September 19 solar flare for energies between 0.5 and approximately 5 MeV per nucleon. The profiles displayed a time dispersion which is inversely proportional to velocity for each individual species. In addition, at a given velocity the time dispersion also depended on the charge to mass ratio of the ion. On the basis of this latter dependence, it was concluded that, while carbon and oxygen are essentially fully stripped, iron nuclei are not, having an effective charge Q = 10 +- 5. The observed dispersion cannot be explained by purely rigidity-dependent diffusive propagation