Higher-order theories for relativistic electron-atom bremsstrahlung in comparison with experiment

Abstract

The analytic Sommerfeld-Maue theory, including the next-to-leading-order correction, and the relativistic Dirac partial-wave theory are probed by a systematic comparison of the bremsstrahlung spectra with available experimental data. These measurements cover a wide range of nuclear charge numbers ($13\ensuremath{\le}Z\ensuremath{\le}79$), collision energies (1--10 MeV), and photon angles (${4}^{\ensuremath{\circ}}\ensuremath{\le}{\ensuremath{\theta}}_{k}\ensuremath{\le}{60}^{\ensuremath{\circ}}$). It is found that the analytic model performs well for $Z\ensuremath{\lesssim}13$ at all angles down to very low photon frequencies. For high charge numbers, at high photon energies (i.e., in the short-wavelength limit) or for the larger angles at all photon energies, the partial-wave theory has to be used. For intermediate $Z\ensuremath{\lesssim}50$, the maximum angle up to which the analytic formulae can be used decreases with increasing $Z$.