The hidden dynamics of relativistic electrons (0.7-1.5 MeV) in the inner zone and slot region

Journal Article · Wed Mar 15 00:00:00 EDT 2017 · Journal of Geophysical Research. Space Physics

DOI:https://doi.org/10.1002/2016JA023719· OSTI ID:1351198

Claudepierre, Seth G.  ^[1]; O'Brien, T. P.  ^[1]; Fennell, J. F.  ^[1]; Blake, J. B.  ^[1]; Clemmons, J. H.  ^[1]; Looper, M. D.  ^[1]; Mazur, J. E. ^[1]; Roeder, J. L.  ^[1]; Turner, D. L.  ^[1]; Reeves, Geoffrey D.  ^[2]; Spence, H. E.  ^[3]

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1. The Aerospace Corp., El Segundo, CA (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
3. Univ. of New Hampshire, Durham, NH (United States)

We present measurements of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region obtained by the Magnetic Electron and Ion Spectrometer (MagEIS) instrument on Van Allen Probes. The data presented are corrected for background contamination, which is primarily due to inner-belt protons in these low-L regions. We find that ~1 MeV electrons were transported into the inner zone following the two largest geomagnetic storms of the Van Allen Probes era to date, the March and June 2015 events. As ~1 MeV electrons were not observed in Van Allen Probes data in the inner zone prior to these two events, the injections created a new inner belt that persisted for at least 1.5 years. In contrast, we find that electrons injected into the slot region decay on much faster timescales, approximately tens of days. Furthermore, we find no evidence of >1.5 MeV electrons in the inner zone during the entire time interval considered (April 2013 through September 2016). The energies we examine thus span a transition range in the steeply falling inner zone electron spectrum, where modest intensities are observed at 0.7 MeV, and no electrons are observed at 1.5 MeV. To validate the results obtained from the background corrected flux measurements, we also present detailed pulse-height spectra from individual MagEIS detectors. These measurements confirm our results and also reveal low-intensity inner zone and slot region electrons that are not captured in the standard background corrected data product. Lastly, we briefly discuss efforts to refine the upper limit of inner zone MeV electron flux obtained in earlier work.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); USDOE
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1351198
• Report Number(s): LA-UR-17-20109
• Journal Information: Journal of Geophysical Research. Space Physics, Vol. 122, Issue 3; ISSN 2169-9380
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
Heliospheric and Magnetospheric Physics