Energy spectrums for proton (200 ev ≲E≲ 1 Mev) Intensities in the outer radiation zone

The directional differential spectrums of proton intensities mirroring near the magnetic equator in the outer radiation zone are obtained for the energy range 200 ev ≲ E ≲ 1 Mev with measurements from the spacecrafts Ogo 3, Explorer 12 and 14, and Mariner 4. The average proton spectrum is characterized by a single maximum of differential intensities at 5 to 10 kev and monotone decreasing intensities with lower and higher proton energy. It is suggested that the appropriate boundary region for models of radial diffusion of protons into the outer radiation zone is located in the vicinity of the earthward edge of the quiettime extraterrestrial ring current at L ≃ 6.5 RE.