RANGE PARAMETERS OF BISMUTH IONS IN POLYSTYRENE

In this study, the Rutherford-backscattering spectrometry was used wit h a 2 MeV He+ ion beam to measure the projected ranges and range strag glings of bismuth ions implanted into polystyrene in the energy range of 40-360 keV. Range-projection equations following the modified Biers ack model and including the first four moments of the nuclear and the electronic energy losses were also employed to perform the theoretical calculations, The feasibility of including the finite maximum-impact parameter and the inelasticity effect in simulating nuclear stopping p rocesses was considered, as well as the surface effect in simulating a finite target medium. Experimental results demonstrate that measureme nts closely correspond to theoretical values, with average differences of 9% for projected ranges and 21% for range stragglings. (C) 1997 El sevier Science B.V.