Stopping Power of Iron for Protons, Theoretical Calculations from Very Low to High Energies

The energy loss in iron is valuable knowledge due to its extended use, technological applications and open topics in fundamental physics. The electronic structure of solid Fe is challenging, being the first of the groups of transition metals with some of the d-electrons promoted to the conduction band while others remain bound. The low energy description, the deviation from velocity proportionality at low impact energies, and the contribution of the loosely bound d-electrons to the energy loss are active featured fields about the stopping in Fe. Very recent TDDFT calculations have been compared with the first stopping measurements in steel, showing surprisingly good agreement. In the present work, we applied a recent model based on the momentum distribution function of the d-electrons to the case of Fe. The comparison with other models is discussed, as well as with the experimental data. We also highlight discrepancies among data sets regarding the stopping maximum and the need for new experimental efforts.