ASYMPTOTICALLY-CORRECT DISTORTED-WAVE CALCULATIONS FOR LOW-ENERGY ELECTRON-IMPACT IONIZATION OF HELIUM

Recently, inclusion of the final-state electron-electron interaction i n the distorted-wave Born approximation was accomplished. The three-bo dy distorted-wave Born approximation (3DWBA) includes the short-range static electron-target interactions for both initial- and final-state wavefunctions that satisfy the correct asymptotic boundary condition. It was shown that the 3DWBA gives a good description of ionization in coplanar asymmetric geometry for the intermediate-energy range (incide nt-electron energies from 5 to 20 times the ionization energy). Here w e apply the theory to low-energy collisions (2 to 5 times the ionizati on energy).