Theoretical investigation of the fully differential cross sections for single ionization of He in collisions with 75-keV protons

Abstract

We present a theoretical investigation of the single ionization of He in collisions with H + projectile ions at 75-keV impact energy. Using the frameworks of the independent-electron model and the impact parameter picture, fully differential cross sections (FDCS) are evaluated in the continuum distorted-wave with eikonal initial-state approximation (CDW-EIS). Comparisons are made to the recent measurements of Schulz et al. [Phys. Rev. A 73, 062704 (2006)] and Arthanayaka et al. [J. Phys. B: At. Mol. Opt. Phys. 49, 13LT02 (2016)]. Strong influence of the internuclear interaction and effects of target core polarization due to the presence of the projectile ion are observed. Comparing the present results to experimental data and other theoretical predictions, it has been found that the CDW-EIS method qualitatively reproduces structures in the FDCS. Projectile coherence effects are investigated by representing the projectile beam as a Gaussian wave packet. Evidence of interference effects due to projectile-electron and projectile-target core interactions are discussed and the need for further theoretical investigations is proposed.

Differential Study of Projectile Coherence Effects on Double Capture Processes in p + Ar Collisions

“…In numerous follow-up experiments, similar projectile coherence effects on the cross sections were observed [20][21][22][23][24][25][26][27][28][29][30] (for a review, see [31]). Furthermore, the interpretation of the experimental data was supported by several theoretical studies, e.g., [32][33][34][35][36].…”

Single Ionization of Helium by Protons of Various Energies in the Parabolic Quasi-Sturmians Approach

“…From the above, it follows that the optimal choice for Q, which provides the most accurate account of the proton-electron interaction achievable within our approach, is the admissible value closest to K 0 . Above such upper bound Q 0 , the p − e potential can no longer be considered as a perturbation (compared with E e f f ), thus resulting in the very poor convergence of the FDCS as more terms are included in the Sturmian representation (21).…”

“…At a lower impact energy, the absolute FDCS of singly ionizing 75-keV p − He collisions have been measured in various kinematical regimes [13]. For these FDCS, theoretical predictions were obtained based upon the well-known continuum distortedwave-eikonal initial-state (CDW-EIS) model [14,15], (a) including the projectile and residual target ion interaction (CDW-EIS PI) [16]; (b) the two-Coulomb final wave (2C) + the initial Coulomb projectile wave [17]; (c) the three-Coulomb wave (3C) model [18]; (d) the modified Coulomb-Born approximation (MCB-PI) [19]; (e) the continuum correlated wave model including the interaction between the projectile and the residual target ion (CCW-PT) [20]; (f) including the projectile target core (NN) interaction model convolved with experimental resolution (CDW-EIS NN) [21]. Despite the sophistication of the latest approaches, none of them has managed to reach complete agreement with the experimental data.…”

Effective fully differential cross-section in single ionization of helium by fast ions

“…Strictly, equation (4) holds exactly in an ideal experiment where two momenta are determined accurately, and K and k are well defined by | ( )| . Note that the expression of the EFDCS depends on the two momenta selected [40,43]. When k e and p r are selected (corresponding to method (c) in section 1), K f can take various values.…”

“…The analysis of Kouzakov [41] is valid when the fluctuation of relative velocity between the projectile and the target is much smaller than the average velocity (see appendix A of [43]), which is usually realized in collision experiments. Recently, Gassert et al [17] reported FDCS data for a 1 MeV proton + He collision.…”