Photo double-ionization of the ns shell of rare gases

The triple differential cross sections (TDCS) for the photodouble ionization of He, Ne, Ar, and Xe leading to the He2+(1s01Se), Ne2+(2s02p61Se), Ar2+(3s03p61Se), and Xe2+(5s05p61Se) states have been measured at about 20 eV above their respective thresholds with the two photoelectrons equally sharing the excess energy. The experimental data are analyzed using a parametrization recently proposed [ J. Phys. B 41 245205 (2008)] which takes into account experimental uncertainties. The parametrization provides a satisfactory representation of the shape of the measured TDCS. The study of the behavior of the gerade amplitude of the TDCS in the different targets gives hints on the dependence of the electron correlation with the principal quantum number n of the ionized ns orbital.