Ratio between double and single ionization as a function of intensity for (a) He in a 120 fs pulse with a wavelength of 390 nm, and (b) Ne in a 40 fs pulse with a wavelength of 400 nm. In (a), the present simulations are compared with the experimental data of Sheehy et al,^[82] the TDSE calculations of Parker et al,^[12] and the calculations of van der Hart and Burnett^[40] based on the rescattering model. All experimental data points were shifted to higher intensity by 50%, as suggested by Parker et al.^[12] In (b), the present results are compared with the experimental data of Ekanayake et al.^[83] Adapted from Ref. [36].