Impact-parameter dependent energy loss of screened ions

We describe a simple model for the electronic energy loss as a function of the impact parameter for screened projectiles at high velocities. The physical inputs are the projectile screening potential, the electronic density and the oscillators strengths for the target electrons. An excellent agreement with full first-order Born calculations is obtained. The results are then used to compute the angular dependence of the electronic energy loss under channeling conditions. (C) 2000 Elsevier Science B.V. All rights reserved.