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Gamma Ray

NSSDCA ID: 1962-012A-02

Mission Name: Ranger 4
Principal Investigator:Dr. James R. Arnold


A gamma-ray spectrometer that consisted of a detector, a 32-channel pulse height analyzer, and a high-voltage power supply was designed to measure the gamma radiation coming from the surface of the moon. The detector contained a beveled 7.62-cm diam cesium iodide crystal surrounded in a phoswich arrangement by a plastic scintillator of .317-cm thickness. This was coupled to a 7.62-cm diam photomultiplier tube. Pulses were passed into the analyzer, which was provided with storage for 2 to the 16th pulses in each channel. Reject circuitry was designed to block the analyzer when charged particles traversed the phoswich. Beacuse of a spacecraft communications failure early in the flight, the gamma-ray boom did not entend and the experiment returned no data.

Alternate Names

  • Ranger4/GammaRay


  • Astronomy: Gamma Ray

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. James R. ArnoldPrincipal InvestigatorUniversity of California, San
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