CALCULATION OF THE CROSS-SECTION FOR E-E- (K ORBIT) PAIRS BY VERY-HIGH-ENERGY FULLY STRIPPED HEAVY-IONS AT PERTURBATIONAL IMPACT PARAMETERS()

The cross section for the production of e+-e- (K orbit) pairs by very- high-energy fully stripped heavy ions is calculated for large impact p arameters, where perturbation theory is valid. To achieve accuracy a l arge range of angular momenta and energies is explicitly computed. The remaining high-angular-momentum and high-energy domain are included b y means of a modified version of an asymptotic expansion devised by Ha ll [Phys. Rev. 45, 620 (1934); Rev. Mod. Phys. 8, 358 (1936)]. An appr oximation to the small-impact-parameter, nonperturbative contribution is taken from previous work to obtain a reliable estimate for the prac tically important Au79+ on Au79+ cross section.