Solar Physics

, Volume 49, Issue 2, pp 395–407 | Cite as

Observation of temporal and spatial variations in the Fe/O charge composition of the solar particle event of 4 July, 1974

  • T. P. Armstrong
  • S. M. Krimigis
  • D. Hovestadt
  • B. Klecker
  • G. Gloeckler


Comprehensive measurements of the temporal variations of the Z ≥ 6 charge composition in the 4 July 1974 solar event made with experiments aboard IMP-7 and 8 show that large variations in the charge composition occur in three-hour-averaged intensities. Hourly averaged fluxes show variations as large as factors of 3 to 4 from one hour to the next and 3 hour averages show nearly a factor of 10 peak to minimum over the event. The precision of the measurements are limited by counting statistics of the Fe-group channel. Iron to oxygen variations are established by both rate channel and pulse height analysis techniques. Comparison of measurements from IMP-7 and 8, separated by about 70 RE shows that, while significant differences in composition and intensity exist for brief periods, the gross compositional variations are reproduced well at both spacecraft. These observations provide particularly stringent conditions for theories of the acceleration, release, and propagation of solar energetic particles.


Oxygen Iron Temporal Variation Spatial Variation Compositional Variation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© D. Reidel Publishing Company 1976

Authors and Affiliations

  • T. P. Armstrong
    • 1
  • S. M. Krimigis
    • 2
  • D. Hovestadt
    • 3
  • B. Klecker
    • 3
  • G. Gloeckler
    • 4
  1. 1.University of KansasLawrenceU.S.A.
  2. 2.Applied Physics Laboratory, The Johns Hopkins UniversityLaurelU.S.A.
  3. 3.Max Planck Institut fur Extraterrestrische PhysikGarchingWest Germany
  4. 4.Universty of MarylandCollege ParkU.S.A.

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