Energy sharing and angular distribution in the double photoionization of helium

The double photoionization of an atom is considered in the near-threshold domain. The angular correlation pattern is analyzed for an arbitrary sharing of the excess energy by the electrons. The motion over the hyperspherical radius R is treated semiclassically which casts the problem in a nonstationary form. For motion over the hyperspherical angle {α} the set of classical trajectories is considered. They converge to the same (R{→}{∞}) limit which corresponds to a chosen energy-sharing ratio. For each {α}(R) trajectory the quantum wave packet (over the correlation angle θ₁₂) is propagated from the inner zone to the region of free-electron motion. At the border of the reaction zone a realistic boundary condition is imposed. The cross sections exhibit a weak dependence on the energy-sharing ratio.