Skewness of energy-loss straggling and multiple-scattering energy distributions

Energy spread distributions due to electronic energy-loss straggling and multiple small-angle scattering of swift ions in matter are approximated by asymmetric Gaussian functions consisting of two-piece normal distributions. These skewed energy distributions approximate the distributions more accurately than the conventional approximation by Gaussian functions. The results are compared to experimental data and Monte-Carlo simulations using the MCERD code and are in good agreement. The use of these skewed distributions allows to achieve a higher accuracy in the computer simulation of ion beam analysis energy spectra.