Scattering of electrons by hydrogen atoms at intermediate energies: Elastic differential cross sections from 10 to 30 eV

The elastic scattering amplitude obtained from an open pseudostate calculation employing the algebraic variational method for partial waves of angular momentum $0<L<3$, is combined with phase shifts obtained in the extended polarization approximation for $4<L<99$ to obtain elastic differential cross sections for electron-hydrogen scattering for electron energies in the range 10-30 eV. Elastic angular distributions have been measured using a crossed-electron modulated-atom-beam method and absolute cross-section values determined using a phase-shift analysis method. The measurements include energies from 10 to 30 eV and angles from 10^∘{} to 140^∘{} with estimated experimental error limits of ±{} 17%. Within these error limits they are in agreement with the theoretical predictions except at 20 to 26 eV for angles greater than or equal to 120^∘{}, where the theoretical values are significantly higher than allowed by these error limits.