Reza Fathi

Excitation of hydrogen atoms at intermediate and high energies by proton impact under a three-body Born–Faddeev-type formalism

In this work, differential cross sections have been calculated for the excitation of atomic hydrogen (H) from its ground state (1s) into a selection of its excited states (2s, 2p0, 2p±1 and 3s). The present study was conducted at intermediate and high proton impact energies within the range 50 keV–1 MeV. A three-body model based on Faddeev-type equations is implemented, while near the energy shell the two-body Coulomb transition matrix was used to calculate the transition amplitude. Second and higher order approximations have been ignored in this case. The resulting amplitudes are subsequently utilized to calculate total and differential cross sections for the corresponding excitation processes. These calculated cross sections have then been compared with available experimental data and other theoretical results from the literature.

Total single electron capture cross sections for collisions of multicharged ions with He atoms

The three-body boundary corrected Born distorted wave method is utilized to compute the total cross sections for single electron capture in the collisions of the fast ions (, He, Li, and ) with helium targets in their ground states. Both post and prior forms of the transition amplitude are obtained in terms of two-dimensional integrals and the total cross sections are computed via three-dimensional numerical integrations. The present results show reasonable agreement with the measurements and three- and four-body theoretical computations, especially at higher incident energies.

Application of Haar multi-resolution analysis in subspace V2 to calculate Faddeev partial amplitudes of electron transfer in three-body proton-hydrogen scattering

The exact or projected form of the off-the-energy-shell Coulomb transition matrix (T-matrix), in the Daubechies first scalet basis, is used to calculate the Faddeev–Watson–Lovelace (FWL) amplitudes up to the second order, in the electron capture channel for the scattering of high-energy protons by atomic hydrogen. The phase, angular and energy dependence of the FWL partial amplitudes and differential cross sections are constructed. An analytical expression for the differential cross sections is presented as a function of energy and scattering angle. Finally, differential cross sections obtained by the exact and approximate Coulomb off-the-energy-shell T-matrix are compared with the available experimental results.

Polarization of Lyman-α and Balmer-α emission in proton-hydrogen collisions: a study using first-order Born-Faddeev- type equations

A three-body Born‐Faddeev model is devised to calculate the total cross sections of Balmer-α and Lyman-α emissions, for the excitation of hydrogen atoms by proton impact in the energy range of 100 keV‐7 MeV. In addition, the polarization alignment factor A20 is calculated and compared against available experimental data to further test the theory. Specifically, here we use the Faddeev‐Watson‐Lovelace formalism to study the excitation of atomic hydrogen from its ground state to the excited states of n = 2 and 3 and magnetic sublevels l = 0, 1 and 2, wherever applicable. The first-order electronic, A (1) e , and the first-order nuclear, A (1) n , amplitudes are considered in order to calculate the excitation transition matrix (TPT), while a near-the-shell condition is assumed throughout. In addition, our results were used to calculate the first-order form factors. The present results are compared, where possible, with those of other theoretical and experimental works that are currently available in the literature.

Antihydrogen produced in the charge transfer channel by the collision of antiprotons and positronium

In the present study, the differential and total cross sections due to the collision of antiprotons and hydrogen atoms in the charge transfer channel is calculated to form antihydrogen. The state of the incoming particles was assumed to be plane wave or Coulomb distorted wave. The impact energies of 11.3, 13.3 and 15.8 keV were assumed to be able to compare the results with the available experimental data for the total charge transfer channel.

Differential cross section for positron formation in Positron - molecular hydrogen ion

The present work deals with the study of positronium formation from diatomic molecular ion targets by the impact of energetic positron. The high and intermediate energy positron scattering are considered using corrected boundary conditions method. The transfer of an electron from a molecule by a fast positron is considered assuming an effective one electron model. The results are presented as differential cross sections.

Polarization of Lyman-Alpha and Balmer-Alpha in proton-hydrogen collision measured under three-body Faddeev type formalism

The alignment parameter is calculated to check the three-body Born-Faddeev formalism in excitation channel for ion impact of atomic targets.

A self-consistent central potential to simulate methane in scattering calculations

A central potential scattering is determined for an active electron in a molecular target. This can be used for the interaction of fast projectiles with a molecular target. We have substituted the molecular orbital into the Schrodinger equation to find a central potential which best resembles the methane molecule in any interaction that could be simplified as a three-body one. The derived central potential was fitted to a potential composed of a long-range potential (coulomb) and two short-range ones. The resulting potential is attractive in a spherical shell close to the hydrogen atoms in methane. The resulting central potential simulates methane in any calculation that is complicated by the multi-centre character of the molecule. This enables one to use simple potential scattering formulas to investigate reactions involving methane.