Energy shifts of the binary encounter peak (BEP) in 1 MeV/uSi{sup q+} + H{sub 2}

The double differential cross section of the BEP for 1 MeV/u Si{sup q+} on H{sub 2} was measured at 0{degrees} observation angle for q = 5-13. The data were fitted to the theoretical prediction of the impulse approximation (IA) using a two parameter model. The first parameter was a scaling factor which corresponds to the enhancement ratio between the ion of charge state q and the bare ion. The second was an {open_quote}energy correction{close_quote} which enters into the calculation of the energy of the bound target electron in the projectile rest frame. The observed enhancement ratio increases with increasing number of electrons on the projectile, in agreement with previously reported data. The energy correction parameter required to fit the BEP energy decreases with increasing number of electrons on the projectile ion.