Calculation of the actual path length of charged particles after passing through a thin film

Inelastic energy losses of ions in the target are proportional to the ion path length which may differ essentially from the target width because of the multiple elastic collisions between ions and target atoms. The ratio of the ion path length $L$ to the film width $D$ depends on the ion energy and masses of ions and target atoms. In the present work we calculated the ratio $L/D$ by the method of computer simulation. The elementary analytical theory of the phenomenon is developed also.