Double photoionization of helium atoms at 1 eV above threshold

An ab initio calculation of triple differential cross-section (TDCS) for double photoionization of helium atoms are presented for a very low energy of just 1 eV above threshold in the equal energy sharing kinematics. We have used hyperspherical partial wave theory together with a Numerov difference scheme in place of other schemes used in our earlier works. The curve representing TDCS against the scattering angle θ shows 3 peaks for θ = -25, -90 and -160 degrees. The 2 first peaks were predicted both in our results and in experiments while the third peak is absent in experimental data