Energy and angular distribution of electrons ejected from argon by 5-keV to 1.5-MeV protons

Cross sections, differential in emission energy and angle, have been measured for the ejection of electrons in collisions of ${\mathrm{H}}^{+}$ with argon gas targets. Incident-proton energies studied were from 5 keV to 1.5 MeV and electron emission angles ranged from 10° to 160°. Integration of the double-differential cross sections over emission angle and energy yield results in good agreement with direct measurement of total ionization cross sections. The electron distributions are compared to two plane-wave Born-approximation calculations, one using Hartree-Slater wave functions and the other using Hartree-Fock wave functions in the $3p-\epsilon d$ channel.