Stopping powers for electrons and positrons

This report supplies up-to-date stopping-power information, selected on the basis of the requirements of biomedical dosimetry. Some topics are reviewed which are pertinent to the evaluation of stopping powers for any charged particle within the framework of the Bethe theory. These include shell corrections, the determination of mean excitation energies from experimental data, the use of the Bragg additivity rule for compounds, and the density-effect correction. Recommended values of mean excitation energies are given. In later sections, topics are reviewed which pertain mainly or entirely to electrons. These include the radiative stopping power due to the emission of bremsstrahlung, and the information on electron collision stopping power at energies below 10 keV, where the Bethe theory is no longer fully applicable. Finally, electron and positron stopping-power tables are presented for a large number of elements and compounds, covering the energy region from 10 keV to 1000 MeV. These tables also include the range and the radiation yield (fraction of electron kinetic energy converted to bremsstrahlung as the electrons slow down to rest), both computed in the continuous-slowing-down-approximation. 24 figs., 35 tabs., 245 refs