Restricted Nuclear Stopping

Abstract

This chapter addresses the central question of experimentally separating nuclear from electronic stopping. Reference is made specifically to transmission experiments in which the energy-loss spectrum of ions emerging downstream from the target is measured over a narrow angular interval around the initial beam direction. Ions that have undergone a violent nuclear collision will typically be deflected outside the acceptance angle of the detector. Therefore the full (unrestricted) nuclear stopping cross section will not contribute to the observed energy-loss spectrum. Conversely, ions exiting in the forward direction will typically have undergone a series of small-angle nuclear-scattering events. Hence some nuclear stopping will be recorded. The corresponding restricted nuclear-stopping cross section can be expected to vary slowly with angle within the multiple-scattering cone. More important, it will depend sensitively on the penetration depth. ...