DOUBLE PHOTOIONIZATION OF HELIUM - USE OF A CORRELATED 2-ELECTRON CONTINUUM WAVE-FUNCTION

A correlated two-electron continuum wave function satisfying the correct asymptotic boundary condition is used to calculate double-photoionization cross sections. It is built up as a product of three two-body Coulomb continua. As a highly correlated ground-state wave function is employed, the present results serve as a critical test of the two-electron continuum wave function on this double process. For all energies, the results exhibit a large discrepancy between the length and velocity forms. In the high-energy limit, the velocity form agrees quite well with recent synchrotron measurements and with previous calculations. At low photon energies, the approximation fails to account for the data in magnitude and shape.