Atomic ionization by electron impact

The field of atomic ionization by electron impact is several decades old. In that period of time significant progress has been made in several aspects of the problem and we have learned a lot about ionizing collisions as a result of this work. Over the years both the experiments and theories have improved dramatically. Experiments are now able to measure absolute triple differential cross sections for both in-plane or out-of-plane geometries. Theories have been getting better and better at including all the 3-body interactions in the wavefunction for the system. However during the history of the field experiment has been ahead of theory and it is just very recently that theory has started to catch up. In this paper we will show that theory is now able to accurately predict the results of electron impact ionization of hydrogen for intermediate and higher energies.