SPATIAL VARIATION OF GREATER-THAN-40 MEV N NUCLEI FLUXES OBSERVED DURING THE ULYSSES RAPID LATITUDE SCAN/

In this paper we present fluxes of galactic cosmic ray nuclei with ene rgies above 30 MeV/n observed by the Kiel Electron Telescope on board the Ulysses spacecraft during the fast scan from the South Pole (Septe mber 1994) to the North Pole (July 1995). This part of the Ulysses orb it gives us the unique opportunity to investigate spatial modulation o f cosmic rays under solar minimum conditions. We show that during this time period temporal variations are well ordered with particle rigidi ty using 1 AU data from the University of Chicago particle instrument on board IMP8. The latitudinal variation is particularly strong for 38 -125 MeV/n helium nuclei and decreases with increasing energy. In cont rast, the spatial. variation for protons is most dominant in the energ y range of a few hundred MeV. Spatial effects are very small for some ten to one hundred MeV protons. The proton results are compared with p redictions of a steady-state modulation model which takes into account modifications of the large scale heliospheric magnetic field and an i ncreased level of cosmic ray scattering over the poles. We find that t he model is in excellent agreement with the latitudinal variations of >2 GeV protons, whereas it does not reproduce the behaviour at low rig idities. We conclude that either the assumed rigidity dependence for t he diffusion coefficients at low energies has to be modified or that t ime-dependent modulation effects dominate at low energies.