MONTE-CARLO SIMULATION OF RBS SPECTRA - COMPARISON TO EXPERIMENTAL AND EMPIRICAL RESULTS

For low projectile energies, Rutherford backscattering (RBS) spectra from thin targets show a low energy background which can be explained by plural and multiple scattering of the projectiles. Knowledge about the influence of plural and multiple scattering on the shape of RBS spectra is important in many fields (e.g. RBS depth profiling, determination of projectile energy loss). Analytic calculation of RBS spectra with full inclusion of plural and multiple scattering is impossible. Therefore we used Monte Carlo computer simulations to calculate RBS spectra for 100-200 keV protons backscattered by thin gold films (1000 Å). In order to limit the number of scattering events, a nonzero minimum scattering angle (cutoff angle) was used in the simulations. The cutoff angle must be chosen so small that a further reduction does not change the shape of the total spectrum to a significant extent. Therefore, for various cutoff angles, the contribution of single, double and plural scattering to the total RBS spectrum is discussed. Furthermore, simulated spectra are compared to experimental data and to the empirical formula presented by Weber and Mommsen [2]. © 1990.