Theoretical and experimental study of the correlation between forward and backward electron emissions induced by H$^0$ or H$^+$ projectiles incident on carbon foils

The emission statistics of secondary electrons emitted from solid targets under ion impact has been recently the object of much interest from a theoretical as well as experimental point of view since it provides very useful information about the electron excitation process in the solid. In the case of very thin targets, it is possible to measure simultaneously the number of electrons emitted from both sides of the target and the exit charge state of the projectile. The resulting two variable (number of electrons emitted in the backward and in the forward directions) statistical distribution shows in some cases a clear correlation between the numbers of electrons emitted from both sides of the target. This correlation between backward and forward emission has been studied from Monte Carlo simulations and from experiments for H0 and H+ projectiles incident on thin carbon foils in the MeV energy range. It is shown that the charge exchange processes of the incident projectiles in the target play an important role in the interpretation of the backward–forward correlation of the secondary electron emission.