Measurement of Vacuum-Assisted Photoionization at 1 GeV for Au and Ag Targets

D. Dauvergne, A. Belkacem, F. Barrué, J. P. Bocquet, M. Chevallier, B. Feinberg, R. Kirsch, J. C. Poizat, C. Ray, D. Rebreyend
2003 Physical Review Letters  
We report a measurement of photon impact ionization of K and L-shell of Au and Ag targets in the 1-GeV energy range. We show that the cross section is dominated by a contribution from a new channel called vacuum-assisted photoionization. In this process the energymomentum balance associated with the removal of the inner-shell electron is obtained by a conversion of the high-energy photon into an electron-positron pair. This measurement confirms the theoretical prediction that vacuum-assisted
more » ... vacuum-assisted photoionization is the most probable ionization mechanism at very high energies.
doi:10.1103/physrevlett.90.153002 pmid:12732031 fatcat:q2w6vo3kxnc45nimicl7qdeye4