K-SHELL IONIZATION OF ATOMS BY ELECTRON AND POSITRON-IMPACT

In the plane-wave Born approximation (PWBA), scaling relations for K-shell generalized oscillator strengths and energy-loss cross sections of atoms are given. The total K-shell ionization cross sections, obtained at high impact energy, are used to obtain the Bethe collisional parameter c(K) for atoms ranging from carbon to gold. These values of c(K) are, in general, significantly different from those obtained previously with the help of Fano plots at relatively low impact energies. Furthermore, using Hippler's modification of the PWBA [Phys. Lett. A 144, 81 (1990)), total K-shell ionization cross sections of various atoms by electron and positron impact are calculated over a wide energy range. The electron-impact ionization cross sections for light atoms are in satisfactory agreement with the experimental data.