Calculation of the cross section fore+-e−(Korbit) pairs by very-high-energy fully stripped heavy ions at perturbational impact parameters

The cross section for the production of ${\mathit{e}}^{+}$-${\mathit{e}}^{\mathrm{-}}$ (K orbit) pairs by very-high-energy fully stripped heavy ions is calculated for large impact parameters, where perturbation theory is valid. To achieve accuracy a large range of angular momenta and energies is explicitly computed. The remaining high-angular-momentum and high-energy domain are included by means of a modified version of an asymptotic expansion devised by Hall [Phys. Rev. 45, 620 (1934); Rev. Mod. Phys. 8, 358 (1936)]. An approximation to the small-impact-parameter, nonperturbative contribution is taken from previous work to obtain a reliable estimate for the practically important ${\mathrm{Au}}^{79+}$ on ${\mathrm{Au}}^{79+}$ cross section.