Semi-empirical inelastic mean free paths for positrons

Previously, we developed a semi‐empirical method for determining the inelastic mean free paths of positrons in a wide variety of materials. This work is heavily based on the earlier work of Tanuma, Powell and Penn on the inelastic mean free paths of electrons in the 50–2000 eV energy range. One of the remaining questions still to be answered was the validity of ignoring terms of the order of the inverse energy squared in the denominator of our final expression. In this paper, we investigate this question in some detail by comparing our approximations with calculated values of the positron inelastic mean free paths based on experimental optical data. We conclude that the exclusion of the higher order terms is consistent with the other approximations in this methodology. Copyright © 2005 John Wiley & Sons, Ltd.