spase://SMWG/Instrument/Pioneer11/GTT

This experiment used seven miniature Geiger tubes in three arrays to measure proton and electron fluxes near Jupiter and Saturn. Detector groupings were as follows: (1) a three-element (A, B, and C) differentially shielded telescope. Tube C was shielded omnidirectionally and was used for background subtraction to provide rates such as A-C (5 to 21 MeV electrons and 30 to 77.5 MeV protons) and B-C (0.55 to 21 MeV electrons and 6.6 to 77.5 MeV protons); (2) a three-element triangular array, each element responding to electrons above 31 MeV and protons above 77.5 MeV; and (3) a thin-window tube (G) with a gold-plated elbow as the entrance aperture to admit scattered electrons above 0.06 MeV while discriminating strongly against protons. For a description of the similar experiment on Pioneer 10, see J. A. Van Allen et al., J. Geophys. Res., v. 79, p. 3395, 1974. Early results are given in Science, v. 188, p. 459, 1975. Data include the interplanetary region.