Elastic and Inelastic Scattering of Protons by Hydrogen Atoms

The Glauber approximation is applied to elastic scattering of protons by hydrogen atoms and to excitation of the $2s$, $2p$, $3s$, and $3p$ levels of the hydrogen atom by proton impact. The predicted differential and integrated elastic and excitation cross sections are compared with other calculations and with the available experimental data. A minimum appears in both the $1s-2s$ and $1s-3\mathrm{s}$ integrated cross sections near 15 keV. The corresponding differential cross sections near 15 keV exhibit a minimum and a maximum at very small scattering angles. The Glauber approximation is a considerable improvement over the Born approximation at energies < ∼ 200 keV and the distortion approximation at energies < ∼ 100 keV. At energies > ∼ 200 keV, our calculated total excitation cross sections are close to the Born approximation. Nevertheless, over most of the angular range our calculated differential cross sections are very different from the Born-approximation values. Above 10 keV our results are in good agreement with the only available experimental data ($1s-2p$), indicating that above ∼ 10 keV the Glauber approximation should yield reasonable estimates for proton-hydrogen-atom collision cross sections.