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Electrons and Hydrogen and Helium Isotopes

NSSDCA ID: 1972-073A-06

Mission Name: IMP-H
Principal Investigator:Prof. Edward C. Stone, Jr.


This experiment was designed to measure solar and galactic electrons, positrons, and nuclei, and to separate isotopes from hydrogen through oxygen. The energy ranges covered were 0.16 to 5 MeV (electrons), 0.16 to 2 MeV (positrons), and about 1 to 40 MeV/nucleon for nuclei. The instrument was a telescope consisting of 11 colinear, fully depleted, silicon surface-barrier detectors inside a plastic scintillator anticoincidence shield. Four of the top five sensors were annular while the remainder were solid disks. This arrangement gave narrow geometry (anticoincidence in annular sensors) and wide geometry modes with half-angle acceptance cones of about 24 and 36 deg. The telescope axis was perpendicular to the spacecraft spin axis. Data returned consisted of 8-sectored and spin-integrated count rates for 8 different coincidence/anticoincidence modes and 2 parameter pulse-height analyses for 32 particles every 20.48 s. The coincidence mode chosen for pulse-height analysis in any 0.64 s interval was fixed by a five-level priority system. The principal contributors to each coincidence mode rate were (1) 0.16- to 5-MeV electrons and 1- to 43-MeV/nucleon nuclei, (2) 1- to 5-MeV electrons and 13- to 43-MeV/nucleon nuclei, (3) neutrals and gamma rays, (4) 0.2- to 1-MeV electrons, (5) 1- to 3-MeV electrons, (6) 1.2- to 2.4-MeV/nucleon nuclei, (7) 4- to 13-MeV/nucleon nuclei, and (8) electrons above 3 MeV and nuclei above 30 MeV/nucleon. Additional data can be obtained from the PI.

Alternate Names

  • IMP-H/ElectronsandHydrogenandHeliumIsotopes


  • Space Physics: Magnetospheric Studies
  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Dr. William E. AlthouseGeneral ContactCalifornia Institute of
Dr. Rochus E. VogtOther InvestigatorCalifornia Institute of
Prof. Edward C. Stone, Jr.Principal InvestigatorCalifornia Institute of
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