Results from the Imp 1 GM counter telescope experiment

The results from the GM counter telescope on. board the Imp 1 satellite are presented. The detector system consisted of four pancake-type GM counters forming two mutually perpendicular telescopes and an omnidirectional detector. Comparison of the intensity measured by the two perpendicular telescopes reveals an anisotropy in the recovery phase of the 11-year variation. Time variations of the omnidirectional intensity were correlated with the planetary index Kp, and inferences about interplanetary field irregularities and solar wind cavity structures are presented. These results are shown to be in general agreement with Parker's description of the cosmic-ray modulation by the solar wind.