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Energetic Particles and Ion Composition (EPIC)

NSSDCA ID: 1992-044A-03

Mission Name: Geotail
Principal Investigator:Dr. Richard W. McEntire


The principal objective of the EPIC (energetic particle and ion composition) investigation is to explore the distant magnetotail region and obtain information on the origin, transport, storage, acceleration and dynamics of suprathermal and non-thermal particle populations. The instrument performs three-dimensional distribution measurements by using both total energy (LEMS -- low energy composition system) and velocity/composition detectors (ICS - ion composition system), measuring ions and electrons with energies >20 keV, and ions with energy >8 keV/nucleon, respectively. Composition measurements are made by using a thin foil time-of-flight technique which resolves the H and He isotopes, and provides elemental resolution up to approximately argon. The instrument also measures the non-thermal components to 6 MeV for protons, 480 keV for electrons, and 400 keV/nucleon for ions with Z>2. Directional measurements with a time resolution <1 s are possible.

Alternate Names

  • EPIC
  • Geotail/EPIC

Facts in Brief

Mass: 21.9 kg
Power (avg): 14.6 W
Bit rate (avg): 2.56 kbps

Funding Agency

  • National Aeronautics and Space Administration (United States)


  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. Ramona L. Kessel



NameRoleOriginal AffiliationE-mail
Dr. Louis J. LanzerottiCo-InvestigatorAT&T Bell
Dr. Thomas P. ArmstrongCo-InvestigatorUniversity of Kansas
Prof. George GloecklerCo-InvestigatorUniversity of
Dr. Stamatios M. KrimigisCo-InvestigatorApplied Physics
Dr. Edward C. RoelofCo-InvestigatorApplied Physics
Dr. Ching I. MengCo-InvestigatorApplied Physics
Dr. Robert E. GoldCo-InvestigatorApplied Physics
Dr. Anthony T.Y. LuiCo-InvestigatorApplied Physics
Dr. Fred M. IpavichCo-InvestigatorUniversity of
Prof. Emmanuel T. SarrisCo-InvestigatorUniversity of
Dr. Fritz O. GliemCo-InvestigatorTechnische Universitat Braunschweig
Dr. Richard W. McEntirePrincipal InvestigatorApplied Physics

Selected References

  • Williams, D. J., et al., Energetic particle and ion composition instrument (EPIC), in Geotail Prelaunch Report, SES-TD-92-007SY, Institute of Space and Astronautical Science, SES Data Center, pp. 157-178, Apr. 1992.
  • Nishida, A., et al., Geotail mission to explore earth's magnetotail, EOS, 73, No. 40, Oct. 1992.
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