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Low-Energy Proton and Electron Differential Analyzer (LEPEDEA)

NSSDCA ID: 1967-073A-10

Mission Name: OGO 4
Principal Investigator:Prof. James A. Van Allen


The objectives of this experiment were to conduct a comprehensive latitude and temporal study of the intensities and energy spectra of electrons and protons precipitating into the earth's upper atmosphere and to provide information on the spatial, angular, and temporal distribution of geomagnetically trapped proton and alpha particles. The instrumentation used for the study of precipitating particles was a Low Energy Proton and Electron Differential Energy Analyzer (LEPEDEA) with 16 energy bands in the range 5 to 5.E4 eV. A single thin-window Geiger tube was provided for an integral measurement of electron flux above 40 keV and of proton flux above 500 keV. Two solid-state detectors were used for the trapped particles study. One was an alpha particle experiment with four energy bands in the range 1.05 MeV to 7.8 MeV. The other was a proton experiment with four energy bands in the range 0.37 MeV to 9.9 MeV. The experiment package was mounted on the short boom EP-4 and yielded data from launch until October 1969, at which time the spacecraft was placed in a standby status. The data, however, were of very limited value because of a severe temperature problem in the instrument package.

Alternate Names

  • Trapped and Precipitating Particles


  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Prof. Louis A. FrankOther InvestigatorUniversity of
Prof. James A. Van AllenPrincipal InvestigatorUniversity of Iowa
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