Ejection of quasi free electron pairs from the helium atom ground state by a single photon

M. S. Schöffler1,∗ C. Stuck, M. Waitz, F. Trinter, T. Jahnke, U. Lenz, M. Jones, A. Belkacem, A. Landers, C. L. Cocke, J. Colgan, A. Kheifets, Igor Bray, H. Schmidt-Böcking, R. Dörner, and Th. Weber 1 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA 2 Institut für Kernphysik, University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany 3 Department of Physics, Auburn University, Auburn, AL 36849, USA 4 Department of Physics, Kansas State University, Manhattan, KS 66506, USA 5 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA 6 Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia and 7 ARC Centre for Matter-Antimatter Studies, Curtin University, WA 6845 Perth, Australia (Dated: July 2, 2012)