Direct excitation, ionisation and energy loss in proton-atomic-hydrogen collisions at impact energies from 30 keV to 5 MeV

As a preliminary part of an investigation of the proton/antiproton interactions with matter, semiclassical impact parameter cross sections for direct excitation and ionisation of atomic hydrogen by proton impact have been computed in a wide energy range from 30 keV to 5 MeV. The coupled-state calculations used a 51-state two-centre atomic orbital expansion. The computed cross sections are in excellent agreement with available experimental data. Calculations of energy loss for protons moving in a gas of atomic hydrogen are also reported.