Photoionization of radium: Investigating many-body effects at high Z - art. no. 022717

The total and partial photoionization cross sections, branching ratios, and photoelectron angular-distribution asymmetry parameters have been calculat ed for atomic radium (Z = 88) for all subshells from the 7s valence shell d own to the deep n = 3 subshells. The relativistic random-phase approximatio n, the relativistic random phase approximation modified to include relaxati on effects, and the relativistic random-phase approximation modified to inc lude relaxation effects and Auger decay were all used to determine the rela tive importance of various many-body effects such as interchannel coupling, core relaxation, and Auger decay. Comparisons are made between the various theoretical models and experimental data for the total cross sections. Int erchannel coupling was found to be important for most subshells. Relaxation effects were found to be significant for calculations of the total cross s ection above the 5d threshold and to have a very large effect on the 5p par tial photoionization cross section.