Upper limit on the inner radiation belt MeV electron intensity

X Li; Rs Selesnick; Dn Baker; An Jaynes; Sg Kanekal; Q Schiller; L Blum; J Fennell; Jb Blake

doi:10.1002/2014JA020777

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Upper limit on the inner radiation belt MeV electron intensity

Journal article

Open access

Peer reviewed

Upper limit on the inner radiation belt MeV electron intensity

X Li, Rs Selesnick, Dn Baker, An Jaynes, Sg Kanekal, Q Schiller, L Blum, J Fennell and Jb Blake

Journal of Geophysical Research. Space Physics, Vol.120(2), pp.1215-1228

02/01/2015

DOI: 10.1002/2014JA020777

PMCID: PMC4497489

PMID: 26167446

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Abstract

No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere

Astrophysics

CubeSat

Earth

Earth's magnetosphere

inner radiation belt

MeV electron

Nuclear Experiment

Planetary Astrophysics

Research Articles

Van Allen Probes

Details

Title: Subtitle: Upper limit on the inner radiation belt MeV electron intensity
Creators: X Li - University of Colorado Boulder
Rs Selesnick - U.S. Air Force Research Laboratory Space Vehicles Directorate
Dn Baker - University of Colorado Boulder
An Jaynes - University of Colorado Boulder
Sg Kanekal - Goddard Space Flight Center
Q Schiller - University of Colorado Boulder
L Blum - University of California, Berkeley
J Fennell - The Aerospace Corporation
Jb Blake - The Aerospace Corporation
Resource Type: Journal article
Publication Details: Journal of Geophysical Research. Space Physics, Vol.120(2), pp.1215-1228
DOI: 10.1002/2014JA020777
PMID: 26167446
PMCID: PMC4497489
NLM abbreviation: J Geophys Res Space Phys
ISSN: 2169-9380
eISSN: 2169-9402
Publisher: Blackwell Publishing Ltd
Grant note: 0940277 / National Science Foundation (nsf_________::NSF)
Language: English
Date published: 02/01/2015
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984199699402771

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