Study of the influence of the electron capture and loss process on the secondary electron emission induced by protons in aluminium

Experiments on the secondary emission of electrons from thin carbon foils bombarded with protons have shown that the forward-backward yield ratio increases with energy below 200 keV. Theoretical calculations for an aluminium target, on the contrary, show that this ratio decreases with energy. To explain this discrepancy, we have included in our Monte Carlo simulation model the electron capture and loss process, assuming that a proton-captured electron system does not excite electrons in the solid. We have also taken into account the partial yield due to the lost electrons. This simple model, applied to aluminium, gives results consistent with the carbon experiments. We have also studied the statistics of the number of secondary electrons accompanying an outgoing proton or hydrogen atom.