ZDependence of Bremsstrahlung Radiation from Free Atoms

Relative bremsstrahlung cross sections have been measured for free atoms, with atomic numbers in the range $Z=2\mathrm{}$ to $Z=92\mathrm{}$, at low incident electron energies of 2.5 and 10 keV. The results agree reasonably with a theoretical calculation of Pratt et al., except at the largest $Z$ number, where differences of up to a factor of 2 at low photon energies are observed.