Role of Projectile Coherence in Close Heavy Ion-Atom Collisions

We have measured fully differential cross sections for single ionization and transfer ionization (TI) in 16 MeV ${\mathrm{O}}^{7+}+\mathrm{He}$ collisions. The impact parameters mostly contributing to single ionization are about an order of magnitude larger than for TI. Therefore, the projectile beam was much more coherent for the latter compared to the former process. The measured data suggest that, as a result, TI is significantly affected by interference effects which are not present in single ionization.

Figure 1

Measured fully differential cross sections (FDCS) for electrons with an energy of 8 eV ejected into the scattering plane (left panel) and into the azimuthal plane (right panel). The open symbols represent single ionization data and the closed symbols transfer-ionization data. The momentum transfer was fixed at 1.5 a.u.

Figure 2

Same as Fig. 1, but the FDCS were integrated over all magnitudes of the momentum transfer.