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Electron-Proton Spectrometer

NSSDCA ID: 1964-040A-04

Mission Name: Vela 2A
Principal Investigator:Dr. Samuel J. Bame


This experiment consisted of one Geiger counter and one hemispherical electrostatic analyzer. They were designed to study the intensity energy spectrum and angular distributions of solar wind and magnetospheric particles. The Geiger counter measured electrons with energies greater than 45 keV. Particles were accepted from a cone of 35 deg half angle. The counter was mounted so that the axis of the acceptance cone was perpendicular to the spin axis. The counter was operated only in real time and a measurement was taken once each second. The electrostatic analyzer was mounted on the spacecraft equatorial plane and had a field of view of about 5 deg in spacecraft longitude and about 90 deg in spacecraft latitude. In the real time mode the electrostatic analyzer measured the ion or electron (polarity was selected by ground command) flux in 16 logarithmically spaced energy per charge channels covering the range 0.3 to 20 keV. A complete 16 point energy spectrum was taken centered on each of the following directions in the spacecraft equatorial plane and relative to the spacecraft - sun line -12 deg, -6 deg, 0 deg, 6 deg, 12 deg, 90 deg, 180 deg and 270 deg (minus signs indicate angles to the left (East of the sun). In the real time mode a complete 128 point spectrum was taken every 128 sec. Very little information was obtained in the memory store mode. The instruments worked well over the period of major coverage of the spacecraft.

Alternate Names

  • Vela2A/Electron-ProtonSpectrometer


  • 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
Dr. Samuel J. BamePrincipal InvestigatorLos Alamos National
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