Kinematically complete experimental study of Compton scattering at helium atoms near the ionization threshold

Abstract

Compton scattering is one of the fundamental interaction processes of light with matter. Already upon its discovery [1] it was described as a billiard-type collision of a photon kicking a quasi-free electron. With decreasing photon energy, the maximum possible momentum transfer becomes so small that the corresponding energy falls below the binding energy of the electron. Then ionization by Compton scattering becomes an intriguing quantum phenomenon. Here we report a kinematically complete experiment on Compton scattering at helium atoms below that threshold. We determine the momentum correlations of the electron, the recoiling ion, and the scattered photon in a coincidence experiment finding that electrons are not only emitted in the direction of the momentum transfer, but that there is a second peak of ejection to the backward direction. This finding links Compton scattering to processes as ionization by ultrashort optical pulses [2], electron impact ionization [3,4], ion impact ionization [5,6], and neutron scattering [7] where similar momentum patterns occur.

arXiv comment7 pages, 4 figures

Cited by in corpus (7)

• Observation of Photoion Backward Emission in Photoionization of He and N2
• An Overview of the Compton Scattering Calculation
• Ion and Electron Momentum Distributions from Single and Double Ionization of Helium Induced by Compton Scattering
• Role of the Coulomb Potential in Compton Scattering
• Comparative analysis of the Compton ionization of Hydrogen and Positronium
• A new method that automatically regularizes scattering amplitudes
• The influence of the binding energy on Compton-scattering-driven ionization