Observations of the inner radiation belt: CRAND and trapped solar protons

TitleObservations of the inner radiation belt: CRAND and trapped solar protons
Publication TypeJournal Article
Year of Publication2014
AuthorsSelesnick, RS, Baker, DN, Jaynes, AN, Li, X, Kanekal, SG, Hudson, MK, Kress, BT
JournalJournal of Geophysical Research: Space Physics
Start Page6541
Date Published08/2014
KeywordsVan Allen Probes
AbstractMeasurements of inner radiation belt protons have been made by the Van Allen Probes Relativistic Electron-Proton Telescopes as a function of kinetic energy (24 to 76 MeV), equatorial pitch angle, and magnetic L shell, during late-2013 and early-2014. A probabilistic data analysis method reduces background from contamination by higher energy protons. Resulting proton intensities are compared to predictions of a theoretical radiation belt model. Then trapped protons originating both from cosmic ray albedo neutron decay (CRAND) and from trapping of solar protons are evident in the measured distributions. An observed double-peaked distribution in L is attributed, based on the model comparison, to a gap in the occurrence of solar proton events during the 2007 to 2011 solar minimum. Equatorial pitch angle distributions show that trapped solar protons are confined near the magnetic equator, but that CRAND protons can reach low-altitudes. Narrow pitch angle distributions near the outer edge of the inner belt are characteristic of proton trapping limits.
Short TitleJ. Geophys. Res. Space Physics

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