Differential cross sections for ionization of atomic hydrogen by proton-impact

•Ionization.•Hydrogen.•Born approximations.•Single and double cross sections.•Ground and excited atoms. The process of electron ionization is studied in proton collision with atomic hydrogen in the five initial states (1s, 2s, 2p0, and 2p±1) at intermediate impact energies. The first- and second-Born approximations are applied to calculate the ionization differential cross sections. Double and single differential cross sections are calculated at low electron emission energies. The closured second-Born approximation is applied to calculate the double differential cross sections (DDCSs). At several ejected electron energies, the DDCS is obtained as a function of the projectile scattering angles and also as a function of the electron ejected angles. The single differential cross section (SDCS) is obtained as a function of the ejected electron energy using first-Born approximation. Comparisons are made with available experimental data and previous theoretical calculations.