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Charged Particle (Chicago)

NSSDCA ID: 1961-032A-05

Mission Name: Ranger 2
Principal Investigator:Dr. John A. Simpson


The gold-silicon (Au-Si) surface barrier medium energy range particle detector was designed by the Cosmic Ray Group at the University of Chicago to detect protons with energies between 0.5 and 10 MeV. It consisted of two high-resistivity silicon discs coated with gold and mounted one behind the other. The discs were approximately 5 mm in diameter and 0.2 mm thick. A proton with energy greater than 0.5 MeV but less than 5 MeV would enter the top disc and produce an avalanche of ions that would register a count in the electronic circuit. A proton with energy between 5 and 10 MeV would pass through the top disc and register a count in the bottom disc. A proton with energy greater than 10 MeV would pass through both discs without registering a count.

Alternate Names

  • Ranger2/TripleCoincidentTelescope


  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. John A. SimpsonPrincipal InvestigatorUniversity of Chicago
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