Measurements of low energy electron scattering from atomic hydrogen

Normalized doubly-differential cross-sections and differential cross-sections for the electron impact ionization, excitation to the n = 3 and 4 levels, and elastic scattering from atomic hydrogen have been measured at incident electron energies ranging from 14.6 eV to 40 eV for scattering angles of 10 degrees to 130 degrees. The measurements are normalized to the accurate differential cross-section for the electron-impact excitation of the H (n = 2) level. These measurements were made possible by the use of a new moveable target source which enables the collection of hydrogen energy loss spectra that are free of all backgrounds. Our measurements are in very good agreement with the results of recent theoretical models-the Convergent Close-Coupling model and the Exterior Complex Scaling model.