Regular Article – Atomic and Molecular Collisions
One-electron transfer from helium targets to protons: the BCIS-4B and CDW-3B methods for state-selective and state-summed total cross sections vs measurements
Department of Physics, Faculty of Sciences and Mathematics, University of Niš, P.O. Box 224, 18000, Niš, Serbia
2 Department of Oncology-Pathology, Karolinska Institute, P.O. Box 260, 171 76, Stockholm, Sweden
3 Radiation Physics and Nuclear Medicine, Karolinska University Hospital, P.O. Box 260, 171 76, Stockholm, Sweden
Accepted: 12 April 2023
Published online: 24 May 2023
The relative performance of three- and four-body perturbation methods is evaluated for one-electron transfer in proton–helium collisions in a large interval of impact energies from 10 to 11000 keV. The four-body boundary-corrected continuum intermediate state (BCIS-4B) method and the three-body continuum distorted wave (CDW-3B) method are used to compute the state-selective and state-summed total cross sections for the first four principal quantum number levels of the formed atomic hydrogen. Detailed comparisons of the obtained results with the corresponding experimental data are exploited to establish the lowest energy limit of applicability of the perturbation theories. As is well known, the CDW-3B method strongly departs from the experimental data below about 80 keV. On the other hand, the BCIS-4B method is presently found to successfully describe the measured cross sections at 20–10500 keV. Moreover, in sharp contrast to the CDW-3B method, in all the considered cases, the BCIS-4B method systematically predicts the experimentally observed Massey peaks at the expected positions of matching of the incident velocity and the electron orbital velocity.
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