Theoretical analysis of the double photoionization of the helium dimer*

We study the scattering effects in the double photoionization process of the helium dimer by numerically solving the time-dependent Schr\"odinger equation. To this end, we use a planar two-active-electron model and abridged Hamiltonians to distinguish the contributions from different interactions to the photoelectron angular distributions. We are able to identify the role of the Coulomb interactions between the electrons as well as between the electrons and the nuclei on the emission of the primary as well as the knock-off electron in the double ionization process. Furthermore, the role of the initial state (singlet versus triplet) will be discussed.