Theoretical calculations of internal conversion rates and nuclear excitation by electron capture

Nuclear Excitation by Electron Capture (NEEC) is a resonant process whereby an electron recombines with a highly ionized ion into a deeply bound orbital and transfers the residual energy to the nucleus by exciting a low-lying nuclear state. It can be thought of as the time-reversed internal conversion process. The experimental observation of NEEC has not been confirmed and only a few theoretical groups have attempted to provide excitation rate estimates for this process. We restored an old Livermore code to calculate the internal conversion rate of selected isotopes which compared favorably to the measured rates. We then used an average-atom model to calculate the fractional electron occupation numbers of Mo-93 in a hot plasma and calculated the NEEC rates at various densities and temperatures. Comparisons are made to other works.