Ionization-excitation of H^-and He by Compton scattering

Abstract

We report calculations for exclusive ionization-excitation Compton cross sections, both total and differential in energy transfer, for n = 3-5 of the negative hydrogen ion and the helium atom. We find that, unlike the cross section for n = 1 and 2, the exclusive cross sections for n 3 are not very sensitive to atomic parameters such as geometric size and electron correlation. We discuss differences and similarities of the cross sections when different initial-state wavefunctions are used, and compare with the Compton cross section for collision of a photon with a free electron. Our calculations have been carried out for photon energies from 6 to 60 keV.

Ionization-Excitation of Helium-Like Ions at Compton Scattering

“…Since in the range of asymptotically high energies (ω 1 η) the cross section for ionization with transition into the 2p-state is an order of magnitude smaller than the cross section for ionization with transition into the 2s-state (see [12][13][14]), the cross sections from works [15,16] should be reduced by approximately 10% when compared with our σ + * 2s . Characteristically, the calculations of work [15] are practically independent of the photon energy ω 1 , while work [16] predicts even increase of the cross section Fig. 2a (dotted curve), the contribution of the diagrams in Fig.…”

“…All the curves turn out to be localized in a rather narrow range with respect to the total interval , keV T 2s FIG. 5: Comparison of our calculation (solid curve) with other calculations for helium: [15], [16]. 0 ε ε max allowed by the energy-conservation law.…”

“…In the literature, there are only two papers [15,16] of the same group of authors, where the ionizationexcitation cross section for the helium atom in the energy range ω 1 ∼ η was calculated. However, the approximations used in the calculations [15,16], in our opinion, are not justified.…”

“…In the literature, there are only two papers [15,16] of the same group of authors, where the ionizationexcitation cross section for the helium atom in the energy range ω 1 ∼ η was calculated. However, the approximations used in the calculations [15,16], in our opinion, are not justified. Firstly, the so-called "impulse approximation" was used, in which the cross section is represented as a product of the Klein-Nishina-Tamm cross section and the atomic form factor.…”

Excitation-ionization of helium in high energy collisions

“…(6) above. If the photon is inelastically scattered, but not annihilated, the process is called Compton scattering [8] and the corresponding scattering amplitude has a different overall constant and no factor of (Z/q) 2 , arising from Coulomb scattering between the charged particle in Eq. (6).…”