Angular dependence of the electronic energy loss of 800-keV He ions along the Si left-angle 100 right-angle direction

We present measurements of the stopping power of 800-keV 4He ions channeled along the Si left-angle 100 right-angle axis, as a function of the incidence angle. We compare the experimental results with theoretical calculations by using the impact-parameter-dependent energy loss obtained from the solution of the time-dependent Schroedinger equation through the coupled-channel method. This nonperturbative calculation provides reliable energy-loss results which are in good agreement with the experimental results. copyright 1997 The American Physical Society