Differences in straggling for positrons and electrons

A satisfactory analysis of the physics of straggling was first given by Landau, who approximated the electron-electron cross section for hard collisions by the Rutherford cross section. Data analysis computer codes continue to use the distribution derived by Landau to calculate the energy lost by electrons because of straggling. We have performed a study of straggling distributions incorporating Mo?ller and Bhabha cross sections to evaluate the precision of (e,e’) analyses that use the Rutherford-based Landau formula. In addition, the calculation of the $e^{+}$ straggling distribution is relevant to the analysis of experiments that have been proposed to study dispersive effects in nuclear electromagnetic processes by comparing results obtained from $e^{\mathrm{-}}$ and $e^{+}$ scattering from identical nuclei. Measuring differences in such cross sections requires a high degree of confidence in the data analysis. Since accuracies in cross sections on the order of a few percent are required, any differences in energy-loss mechanisms of the same order must be taken into account. In this work, we study the differences in positron and electron straggling at energies of present-day interest.