F. Maulbetsch et al., ANGULAR-DISTRIBUTIONS FOR DOUBLE PHOTOIONIZATION OF HELIUM - A COMPARATIVE-STUDY, Journal of physics. B, Atomic molecular and optical physics, 28(10), 1995, pp. 341-347
We have performed calculations of the triply differential cross sectio
n (TDCS) for double photoionization of helium. Our calculations are ba
sed on two different nb initio methods, one where the final continuum
state is represented by a product of three Coulomb wavefunctions, with
the dipole matrix element evaluated directly, the other where the fin
al state is represented by a product of two screened Coulomb wavefunct
ions, which is substituted into a Bur formula that in principle yields
exact results. We compare the results of the two calculations with ea
ch other and also with two different sets of experimental data, for va
rious geometries, for various ratios of the energies of the two photoe
lectrons, and for various photon energies such that the total energy o
f the photoelectrons ranges from 0.6-20 eV above threshold. The theore
tical results for the shapes of the TDCS are in good agreement with th
e experimental data and also with each other, although the calculated
absolute values of the TDCS differ. We comment on various features of
the angular distributions.