Target electron ionization in Li$^{2+}$-Li collisions: A multi-electron perspective

The recent development of the magneto-optical trap reaction-microscope has opened a new chapter for detailed investigations of charged-particle collisions from alkali atoms. It was shown that energy-differential cross sections for ionization from the outer-shell in O$^{8+}$-Li collisions at 1500 keV/amu can be readily explained with the single-active-electron approximation. Understanding of K-shell ionization, however, requires incorporating many-electron effects. An ionization-excitation process was found to play an important role [1]. We present a theoretical study of target electron removal in Li$^{2+}$-Li collisions at 2290 keV/amu [2]. The results indicate that in outer-shell ionization a single-electron process plays the dominant part. However, the K-shell ionization results are more difficult to interpret. On one hand, we find only weak contributions from multi-electron processes. On the other hand, a large discrepancy between experimental and single-particle theoretical results indicate that multi-electron processes involving ionization from the outer shell may be important for a complete understanding of the process.\\[4pt] [1] T. Kirchner et al., Phys. Rev. A 89, 062702 (2014);\\[0pt] [2] M. D. \'{S}piewanowski et al., accepted for publication in J. Phys. Conf. Series (2015).