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Gamma-Ray Spectrometer

NSSDCA ID: 1966-078A-02

Mission Name: Luna 11


The scintillation gamma-ray spectrometer was designed to measure the spectral character of the gamma radiation emanating from the lunar surface to assess surface composition. The instrument, housed inside the satellite, consisted of 40x40 mm NaI(Ti) scintillators, with 32 channel energy resolution over the energy range 0.3-3.0 MeV. It could also simultaneously measure the count rate of gamma-ray quanta from 0.3 to 0.7 MeV. The instrument was calibrated on Earth using potassium, thorium, and uranium sources. Control command for the system was relayed from Earth.

Gamma-rays are produced by naturally occurring radioactive elements such as K, Th, and U, and by the interaction of cosmic ray protons and energetic solar flare particles with elements near the surface such as Fe, Si, O, Mg, and H. Gamma-rays can be detected from material on the surface down to a few cm in depth.

Alternate Names

  • Luna11/GammaRaySpectrometer

Funding Agency

  • Russian Space Agency (U.S.S.R)


  • Planetary Science: Geology and Geophysics

Additional Information

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



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