Amplitudes of solar modulation of low energy cosmic rays

We have studied amplitude variations of low energy cosmic rays near earth during the last solar minimum. We find that low energy helium displays a larger amplitude of variation than does hydrogen at the same kinetic energy per nucleon. This is despite the fact that the helium has at least twice as high a magnetic rigidity as the hydrogen and possibly four times as high, depending on the helium charge state. We argue that this is evidence for adiabatic energy loss in the solar wind