Mechanisms of photo double ionization of helium by 530 eV photons -: art. no. 033004

We have measured fully differential cross sections for photo double ionization of helium 450 eV above the threshold. We have found an extremely asymmetric energy sharing between the photoelectrons and an angular asymmetry parameter betasimilar or equal to2 and betasimilar or equal to0 for the fast and slow electrons, respectively. The electron angular distributions show a dominance of the shakeoff for 2 eV electrons and clear evidence of an inelastic electron-electron scattering at an electron energy of 30 eV . The data are in excellent agreement with convergent close-coupling calculations.