Schöffler, M SJahnke, TWaitz, MTrinter, FLenz, UStuck, CJones, MPindzola, M.S.Belkacem, ACocke, C LLanders, A LColgan, J.Kheifets, AnatoliBray, IgorSchmidt-Böcking, HDörner, RWeber, Th2015-12-081742-6596http://hdl.handle.net/1885/35620In a kinematically complete experiment we have measured the photo double ionization of Helium at a photon energy of 800 eV and observed He2+ ions with 0 momentum, corresponding to a back-to-back-emission of the two electrons. The results are in good agreement with theoretical calculations.Author/s retain copyright201410.1088/1742-6596/488/2/0220072015-12-08