AbstractThe angular distribution of 1 MeV protons across layers of amorphous SiO2 of various reduced thickness τ (from 0.2 to 20) is evaluated by Monte Carlo simulation for different interaction potentials. A simple γ−2 potential and a Coulomb potential truncated at the Thomas‐Fermi screening radius turn out to be good approximations at low and high τ values, respectively, while Meyer's detailed calculations are satisfactory on the whole thickness range. The final distribution depends critically on the chosen potential: an γ−1 dependence at small impact parameters is necessary in order to satisfy the central limit theorem at large thicknesses.