Fe^7+^ ionization cross section

The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurements to remove most metastables, resulting in a beam of 94% ground-level ions.

Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992ApJ...398..394A) cross section is up to about 40% larger than our measurement, with the largest discrepancies below about 400eV. The cross section of Dere (2007, J/A+A/466/771) agrees to within 10%, which is about the magnitude of the experimental uncertainties. The remaining discrepancies between our measurement and the Dere calculations are likely due to shortcomings in the theoretical treatment of the excitation-autoionization contribution.