Electron bremsstrahlung angular distributions in the keV energy range

Simpler theories for the shapes of bremsstrahlung cross sections differential in photon energy and angle are examined using numerical data obtained with the partial-wave method for incident electrons of kinetic energy from 1 keV to 500 keV, under the assumption the process is described as a single electron transition in an atomic central potential. For low-Z elements the Born approximation or the Elwert-Haug approach, modified with form-factor screening, give good predictions for the shape of the angular distributions except at forward and backward angles, i.e., the results are good in the main region which contributed to the energy spectrum. While for high-Z elements, such predictions are accurate within about 15%. Analytic properties of the shape of the angular distribution from simpler theories suggest a simple way to paramaterize the results. (author)