The Radial Gradient of 1.2 GV Galactic Cosmic Rays: Ulysses COSPIN/KET Results

The on-going Ulysses mission provides a unique opportunity to study the propagation and modulation of galactic cosmic rays (GCRs) in detail in the three-dimensional heliosphere. The intensity of GCRs is modulated as they traverse the turbulent magnetic field embedded in the solar wind. These particles are scattered by irregularities in the interplanetary magnetic field and undergo convection and adiabatic deceleration in the expanding solar wind. The large-scale heliospheric magnetic field leads to drifts of GCRs in the interplanetary medium. The time history as well as the spatial gradients of electrons and protons are suitable tools to investigate the importance of drifts in heliospheric modulation. In Sepember 2005 Ulysses was at 29°~S and at a radial distance of 4.8~AU. Since latutinal gradients have not been observed at solar maximum during Ulysses fast latitude scan and only during times when the spacecraft was embedded in the fast solar wind of the coronal holes, the timeperiod from 2001 to September 2005 is ideally suited to determine the radial gradient in the inner heliosphere using ACE CRIS and IMP nuclei data. We will discuss the Ulysses observations and compare the e/p-ratio with the IMP and ICE measurements in the 1980s, which reveals a similar time profile.