Rigidity dependence and the correlation with solar activity of the 11-year variation

The rigidity dependence of the modulation of the cosmic-ray intensity has been investigated using ground-based recorders during the period 1960–66. The intensities recorded by stations are found to be consistent with modulation spectra of the form (1−K/P and exp(−K/P) during the periods of increasing and decreasing cosmic-ray intensity. The question of the apparent phase lag of the cosmic-ray intensity behind the solar activity has also been examined. It is shown that the cosmic-ray intensity is well correlated with the emission of the coronal line, λ5303, from the vicinity of the solar equator.