Double K-shell Photoionization of Ne*

Single photon double K-shell photoionization of Ne has been studied experimentally and theoretically over the energy range of 2.3 – 8.5 keV. In particular, the KK/K photoionization ratios have been determined.  The experimental cross sections were obtained via measurements of hypersatellite x-ray emission and the theoretical cross sections were calculated using the R-matrix with pseudostates (RMPS) method for Ne⁸⁺.  Agreement between experiment and theory was quite good, indicating that the 8 outer-shell electrons of the Ne atom do not play an important role in double K-shell ionization, although small discrepancies are noted.  Scaling of the ratio with Z is also investigated.