First observations by the CEPPAD imaging proton spectrometer aboard polar

Academic Article


  • We report on the first observations of magnetospheric energetic particle populations by the Comprehensive Energetic Particle and Pitch Angle Distribution (CEPPAD) experiment on the recently launched NASA POLAR spacecraft. The CEPPAD Imaging Proton Spectrometer (IPS) experiment has been returning excellent measurements of ≥15 keV ions with high angular, temporal, and spectral resolution since its activation shortly after the POLAR spacecraft launch. The POLAR spacecraft is routinely sampling both previously explored and “new” regions and the high sensitivity CEPPAD instruments observe exciting phenomena in virtually every portion of the POLAR orbit. In this paper, we report on CEPPAD IPS measurements of both familiar magnetospheric regions (cusp, plasma sheet, ring current, radiation belt) as well as the unfamiliar (the appearance of energetic particle near apogee at very high magnetic latitudes). We propose that newly discovered polar energetic particles (PEPs) are the signature of either; (1) accelerated magnetosheath particles on open field lines, or (2) hot particles of a severly distorted plasma sheet, both of which occur during periods of northward interplanetary magnetic field (IMF).
  • Authors

  • Spence, Harlan
  • Blake, JB
  • Status

    Publication Date

  • 1997
  • Has Subject Area

    Published In

    Digital Object Identifier (doi)

    Start Page

  • 933
  • End Page

  • 936
  • Volume

  • 20
  • Issue

  • 4-5