Van Allen Probes ECT/MagEIS Background Corrected Electron Flux Measurements: Methods and Initial Findings

Abstract:

We present results from the Magnetic Electron Ion Spectrometer (MagEIS) instrument, part of
the Energetic Composition and Thermal Plasma (ECT) Suite, onboard the NASA Van Allen
Probes spacecraft. The ECT/MagEIS instrument measures radiation belt electrons in the ~20-
4000 keV energy range and protons in the ~60-1000 keV energy range, with high resolution in
both energy and pitch-angle. In addition, the MagEIS electron measurement technique allows
for a full quantification of the source(s) of background contamination in the measurement.
MagEIS is thus able to make clean, reliable electron flux observations in the presence of strong
penetrating backgrounds, for example, contamination from relativistic protons in the inner zone
and inner slot region. We summarize our background correction algorithm, describe the various
sources of background contamination, and present an overview of our initial findings using the
background corrected data set. Understanding the causes and effects of background
contamination in the MagEIS electron data set is crucial for the interpretation and proper use of
such data. The techniques described will facilitate new investigations into the dynamics of the
Earth's electron radiation belts, which have thus far not been possible.