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Charged Particle Instrument (CPI)

NSSDCA ID: 1973-019A-02

Mission Name: Pioneer 11
Principal Investigator:Dr. John A. Simpson


This experiment used two telescopes to measure the composition and energy spectra of solar (and galactic) particles above about 0.5 MeV/nucleon. The main telescope consisted of five collinear elements (three solid state, one CsI, and one sapphire Cerenkov) surrounded by a plastic anticoincidence shield. The telescope had a 60-deg, full-angle acceptance cone with its axis approximately normal to the spacecraft spin axis, permitting 8-sectored information on particle arrival direction. Four elements of the main telescope were pulse-height analyzed, and low- and high-gain modes could be selected by command to permit resolution of the elements H through Ni or of electrons and the isotopes of H, He, and light nuclei. A selection-priority scheme was included to permit sampling of less abundant particle species under normal and solar-flare conditions. The low-energy telescope was essentially a two-element, shielded, solid-state detector with a 70-deg, full-angle acceptance cone. The first element was pulse-height analyzed, and data were recorded by sectors. Data include the interplanetary region.

Alternate Names

  • CPI
  • Charged Particle Composition
  • Pioneer11/ChargedParticleComposition
  • urn:nasa:pds:context:instrument:cpi.p11

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Fields and Particles
  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. John F. Cooper



NameRoleOriginal AffiliationE-mail
Mr. Anthony J. TuzzolinoOther InvestigatorUniversity of Chicago
Dr. Joseph J. O'GallagherOther InvestigatorUniversity of
Dr. John A. SimpsonPrincipal InvestigatorUniversity of Chicago
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