Cosmic ray radial intensity gradients measured by Pioneer 10 and Pioneer 11

The paper reports revised and updated measurements of the cosmic ray radial intensity gradient made with Pioneer 10 and 11 over the radial range 1-5 AU in differential energy windows from 10-70 MeV/nucleon, and for the integral intensity exceeding 70 MeV/nucleon. In most cases small positive gradients are found of the order of a few percent per AU, with evidence for significant temporal variations. Spectral studies show the presence of the 'anomalous' helium component below 50 MeV at all radial distances from 1-5 AU.