Principal Quantum Number Dependence for Positron-Hydrogen Scattering

Over the last two decades, there has been considerable interest in the electron-atom and positron-atom scattering problems. Most of this work has concentrated on elastic scattering and excitation of the lowest energy states. However, due to recent technological advances, it is now becoming possible to examine the excitation of higher lying states experimentally. The important question then concerns whether these higher states contain new information. Earlier, we have examined this issue for electron-hydrogen scattering. The purpose of this work is to examine the N dependence for positron-hydrogen scattering. The second-order distorted-wave method has been used to calculate scattering amplitudes for excitation of s- and p-states of hydrogen for N = 2, 3, 4, 5 and 6. The N dependence of the integrated cross sections, differential cross sections and polarization fractions will be discussed for energies up to 1 keV and the results will be compared with those for electron-hydrogen scattering.