The global features of the modulation of galactic cosmic ray protons and helium nuclei are
studied in the heliosphere from minimum to maximum solar activity with a comprehensive,
three-dimensional drift model and compared to observations measured by PAMELA and AMS02
taken between 2006 and 2017. Combined with accurate very local interstellar spectra (VLIS) for
protons and helium nuclei, this provides the opportunity to study in detail how the proton to
helium (p/He) ratio at different rigidities behaves with increasing solar activity, through solar
maximum conditions and afterward. In particular, the effects at the Earth of the difference in
their VLIS’s, mass-to-charge ratio (A/Z) and those caused by the main modulation mechanisms
are investigated. We find that the rigidity slopes of the parallel and perpendicular diffusion
coefficients below 4 GV should change differently before solar maximum than afterwards to
reproduce the observed p/He ratio, in addition to scaling down (up) the values of the diffusion
and drift coefficients towards (after) solar maximum. The compatibility between the model
computations and observations indicate that the PAMELA and AMS02 measurement of p/He
above ~ 5 GV precisely reveals the difference in the rigidity slopes of their VLIS’s at these
rigidities.