Akiva Ron

Iron plasma: Sensitivity of photoelectric cross sections to different models and general features of the Fermi-Amaldi-Modified model

Abstract Photoelectric cross sections in several atomic models are presented as a function of temperature and density. The models discussed are Thomas-Fermi (TF), Fermi-Amaldi-Modified (FAM), and Debye-Huckel-Thomas-Fermi (DHTF). We also present some systematic results for the less known FAM potential model regarding predictions for: electrostatic potentials, bound electron level energies, pressures, and branching ratios of photoelectric cross sections. The pure iron plasma which we explored had a temperature in the range of 0.2–3 keV and a density in the range of 50–1000 g/cm 3 . Our conclusion is that except near threshold the photoelectric cross sections per fully occupied subshell are less sensitive to changes in density and temperature, at least in the ranges of our investigation, than other factors, such as occupation numbers.

Limitations on the validity of the non-relativistic dipole approximation for photoelectron angular distributions☆

Abstract We present results which exhibit hazards in the use of the non-relativistic dipole approximation in the interpretation of experimental photoelectron angular distributions. Significant deviations from the non-relativistic dipole approximation occur for both low and high Z atoms. In light elements these effects are found in the keV range and even below. In heavy elements they are found even for energies very close to threshold. For total cross sections, in contrast to this angular distribution situation, the surviving integrated relativistic and multipole corrections tend to cancel, so that the non-relativistic dipole approximation holds to surprisingly high energies.