ELECTRON HYDROGEN-ATOM IONIZATION COLLISIONS AT INTERMEDIATE (5I0-20I0) AND HIGH (GREATER-THAN-OR-EQUAL-TO-20I0) ENERGIES

Triple-differential cross sections for ionization of hydrogen atoms by electrons have been calculated both for small- as well as large-momentum-transfer cases at intermediate (I-5(0) - I-20(0)) and high (less than or similar to I-20(0)) energies (I0 being the ionization potential) following a method which uses a final-channel three-particle wave function determined by one of the authors. This wave function resulted from an analysis of the three-particle wave equation in momentum space and is correct to the first order in the interaction potentials. Incidentally, it is also the first-order Faddeev wave function. The wave function has been suitably normalized before it is used. The computed results are generally good. The small-momentum-transfer results are in nice agreement with the experimental data except for a certain angular region which includes the recoil peak. The domain over which the present results agree in trend with the experimental measurements is somewhat larger than that for the distorted-wave-Born-approximation calculation. Large-momentum-transfer results are also in qualitative agreement with experiments. There are indications that quantitatively the present results may be better there. Total-ionization cross-section results are also in excellent agreement with experiment above 200-eV energy. These facts together with the simplicity of the calculation establish that the present method has certain advantages over other existing methods. The present calculation may be the starting point for a more elaborate calculation which will take into account more accurately the correlation and higher-order effects in the final-channel three-particle wave function.