Elastic interaction of MeV/amu heavy multicharged ions with solids

Abstract

Heavy multicharged ion (MCI) moving in solid interacts with nuclei and electrons of the matter atoms. At projectile velocity exceeding Bohr velocity V > V0 the main process is inelastic interaction, i.e. excitation and ionization of bound electrons. Therefore inelastic energy loss of the MCI in the substance is more than the elastic energy loss by order of magnitude. Elastic interaction being the result of electrostatic repulsion of the MCI nucleus and the target atom nucleus is the key mechanism in the point defect production in the whole velocity range. There is a well-known method of elastic interaction cross section calculation for velocity range V < V0. The nuclei of neutral atoms are considered to be screened by bound electrons in the frames of Thomas-Fermi model. The screening becomes less effective in the V > V0 velocity range because the MCI has lost part of its electrons and target atom nucleus is screened only by electrons, orbital velocities which are higher than the collision velocity. Elastic interaction cross section is obtained taking into account the velocity dependence of MCI charge and in accordance with screening length which is also a function of velocity V. Attenuation of the screening effect leads to the marked rise of defect production cross section. Elastic energy loss increase is hardly distinguished from the well-known results.