Maximum Proton Trapping Energy in the Earth Radiation Belt

During the PAMELA satellite experiment started in 2006 onboard the Resurs-DK1 spacecraft (350–600 km, an inclination of 70°), cosmic ray charged particle fluxes in low near-Earth orbits were measured to the beginning of 2016. The data obtained during the experiment on high-energy proton (0.1–10 GeV) fluxes in the radiation belt made it possible to measure maximum proton trapping energies in various solar activity phases. The measurement results showed that the maximum proton trapping energy at L shells of 1.16–1.22 in the periods of both solar activity minimum (2009) and maximum (2014) was ∼2 GeV.