Ivan Mančev

Comparative analysis on total cross sections is performed using the four leading perturbative boundary-proper theories for single charge-exchange in four-body heavy particle collisions at intermediate and high impact energies. These are the boundary-corrected first Born (CB1-4B), the four-body continuum distorted wave (CDW-4B), the boundary-corrected continuum intermediate state (BCIS-4B) and the Born distorted wave (BDW-4B) methods. The present applications are made for direct and inverse processes for which these methods employ different analytical calculations and algorithms in the corresponding computer programs. To cross-validate such varieties, the principle of detailed balance is advantageously explored to correlate the total cross sections for direct and inverse collisions. In this way, it is shown numerically that detailed balancing is fully satisfied for all the four methods. To accurately describe the examined encounters, the appropriate solutions of four-body problems with four active particles (two nuclei and two electrons) are required. The first-order methods (e.g. CB1-4B) are based on one-step pathways with only the projectile-target interactions. The second-order methods (e.g. CDW-4B, BCIS-4B, BDW-4B) describe two-step processes via target ionization followed by capture of the emitted electron. The ejected electron must have high momentum in order to be captured by a fast projectile. This ionization-capture mechanism is a quantum-mechanical analogue of the classical Thomas double scattering. It is suggested that detailed balancing should beneficially be employed as a consistency check for distorted wave computations (direct vs. inverse processes, with the underlying juxtaposition: prior vs. post transition amplitudes and static vs. dynamic correlations).

In my opinion, this version of the manuscript can be published.

Electron capture in collisions of fast alpha particles with atomic hydrogen is studied by means of the prior version of the three-body boundary-corrected intermediatestates method (BCIS-3B). State-selective and state-summed differential cross sections are presented for the final state n up to nmax = {2,3,4}, depending on the incident energy. The contributions from higher excited states with n > nmax are included using the Oppenheimer n?3 scaling law. The observed angular dependencies of the obtained differential cross sections are analyzed in detail, for incident projectile energy values of E = {100, 150, 300} keV/amu (intermediate) and E = {1.3, 2.5, 5.0, 7.5, 12.5} MeV/amu (high energy values).