The Long-Term Variability of the Cosmic Radiation Intensity at Earth as Recorded by

Long-term instrumental measurements of the 1-100GeV/nucleon cosmic radia-tion intensity commenced in the 1930s using ionization chambers1, and in 1951 using neutron monitors2. Together, they showed that the cosmic-ray intensity at Earth varies in response to short-term (<1 year) and the 11-year changes in sola