Multiple scattering of fast electrons and their secondary electron generation within semi-infinite targets

By means of a new film-bulk method, the absorption depth distribution of fast electrons within Be, Al, Cu and Au targets as well as their inner secondary electron SE generation was measured directly. The primary electrons (PE) had initial energies of E O =1-10 keV. The most probable and average absorption depths x m and x respectively were determined as functions of the maximum range R(Z, E O ) in the various target materials of atomic number Z. The characteristic of the inner SE generation has a maximum near the surface and agrees qualitatively with the depth dependence of the energy transfer of scattered PE to the solid obtained by other authors from Monte Carlo calculations. By integration of the measured SE generation functions, the total number of SE within the bulk targets as well as the mean excitation energy E 1 for a single SE were determined.