Characterizing solar flare high energy particles in near-earth orbits

The high-latitude radiation environment at 840 km for the solar minimum period from December 1983 to October 1987 was measured, using a dosimeter on the DMSP/F7 satellite to characterize solar proton events and compare them to events from earlier periods near solar maximum. The solar proton spectra agree well. A method of characterizing the high-energy particles in solar proton events is proposed. It uses a power spectrum index and dose number that can be useful in specifying polar radiation environments for the design of spacecraft. Latitudinal cutoff levels for higher-energy (up to 35 MeV, up to 55 MeV, and up to 95 MeV) particles are also given for the solar proton event periods and compared to calculated cosmic-ray cutoffs.