Diffusion tensor for Galactic cosmic rays in the interplanetary medium with a magnetic field

The Boltzmann kinetic equation is analyzed in the MIID approximation. This analysis requires explicit expression for the collision integral F-e. In the classical theory, F-e = -nuf(mu)((1))Omega (mu), where f(mu)((1)) is the first spherical harmonic in the Galactic-cosmic-ray (GCR) distribution, Omega (mu) are the components of a unit particle velocity vector, and the frequency nu of collisions between GCRs and interplanetary magnetic-field nonuniformities is assumed to be a scalar. The assumption that nu (ij) is a tensor (which is the result of;anisotropy in the interplanetary medium) distinguishes this study from others. Since the anisotropic GCR effects in the heliomagnetosphere are marginal, the nondiagonal elements of tensor nu (ij) were set equal to zero. Our analysis has yielded the diffusion-tensor components D-parallel to, D-perpendicular to, in D-A, which are expressed in terms of interplanetary parameters. The energy dependencies of D-parallel to, D-perpendicular to, and D-A are in good agreement with the experimental data and calculations by other authors, (C) 2001 MAIK "Nauka/Interperiodica".