Mutual projectile and target ionization in 1-MeV/amu N${}^{4+}$ and N${}^{5+}+\mathrm{He}$ collisions

We have studied mutual projectile and target ionization in 1-MeV/amu N${}^{4+}$ and N${}^{5+}+\mathrm{He}$ collisions in kinematically complete experiments by measuring the momenta of the recoil ion and both ejected electrons in coincidence with the charge-changed projectiles. By means of four-particle Dalitz plots, in which multiple differential cross sections are presented as a function of the momenta of all four particles, experimental spectra are compared with theoretical results from various models. The experimental data are qualitatively reproduced by higher-order calculations, where good agreement is achieved for N${}^{5+}+\mathrm{He}$ collisions, while some discrepancies persist for N${}^{4+}+\mathrm{He}$ collisions.

Figure 1

Schematic illustration of the coordinate system of the projectile-target collision.

Figure 2

Four-particle Dalitz plots for MPTI occurring in 1-MeV/amu N${}^{4+}$ and N${}^{5+}+\mathrm{He}$ collisions. The color code along with the size of the points represent the number of events (the cross section) per unit volume of the Dalitz coordinates in a linear representation as indicated in the figure. (a) N${}^{4+}+\mathrm{He}$ experimental result, (b) N${}^{4+}+\mathrm{He}$ EA calculation result, (c) N${}^{5+}+\mathrm{He}$ experimental result, and (d) N${}^{5+}+\mathrm{He}$ EA calculation result.

Figure 3

Longitudinal 4-D plots for MPTI occurring in 1-MeV/amu N${}^{5+}+\mathrm{He}$ collisions. (a) Experimental result, (b) FBA calculation result, (c) TS-2 calculation result, (d) EA$-$FBA calculation result, and (e) EA calculation result.

Figure 4

Longitudinal 4-D plots for MPTI occurring in 1-MeV/amu N${}^{4+}+\mathrm{He}$ collisions. (a) Experimental result, (b) FBA calculation result, (c) TS-2 calculation result, (d) EA$-$FBA calculation result, and (e) EA calculation result.