Gamma-Ray Spectrometer

Description

This experiment, carried on board the command module of the Apollo 16 mission, was used to conduct a geochemical mapping of the lunar surface by observing the emitted gamma radiation from the lunar surface. During the transearth coast phase of the mission, this experiment was used for gamma-ray astronomy. The instrument consisted of a thallium activated sodium iodide scintillation crystal enclosed in a plastic scintillator shield that was placed in anticoincidence with the sodium iodide crystal to prevent events caused by charged particles. In normal operation, the instrument was deployed on a 7.6-m boom to decrease the response of the instrument to cosmic-ray interaction and radioactvie sources in the spacecraft. The energy resolution was 7.5%. The angular resolution on the lunar surface was approximately 2 to 3 deg, or 70 mm.