GEIGER TUBE TELESCOPE

This instrument [photo] measured the intensities, energy spectra, and angular distribution of energetic electrons and protons in interplanetary space and near Jupiter and Saturn. On Pioneer 10, the instrument used an array of seven miniature Geiger-Müller tubes, collectively known as a Geiger Tube Telescope (GTT). Each tube was a small gass-filled cylinder. When a charged particle passed through the gas, an electrical pulse was generated by the applied voltage. Individual pulses from five of the tubes and coincident pulses from three combindations of the seven tubes were transmitted. Protons of energy greater than 5 MeV and electrons with energies greater 40 keV were detected.

On Pioneer 11, one Geiger-Müller tube was replaced by a thin silicon wafer to detect protons in the specific energy range 0.61 to 3.41 MeV. Other minor changes were made to improve the characteristics of the detector system.

The trains of pulses were passed through quasi-logarithmic data processors and then to the radio telemetry system of the spacecraft. Angular distributions were measured as the spacecraft rotated.

Further Details

• Pioneer 10 GTT
• Pioneer 11 GTT