Assessment of the particle radiation environment at L1 and near-Earth space

We investigated the particle radiation environment at the Lagrangian point L1 and in the near-Earth space by performing a systematic analysis of the proton flux data recorded by the EPAM and CPME particle instruments, aboard ACE and IMP-8 in the energy range similar to 0.05-5 MeV and 0.29-440 MeV, respectively. We computed the cumulative distribution functions for all the energy channels of each instrument and studied the radiation variation with respect to solar activity. We obtained energetic proton spectra at 90% cumulative probability for different time periods and determined the worst case scenario, which can be used for operational purposes of the ATHENA mission and for Space Weather related hazards.