State-Selective Single-Electron Capture in Ar6+ - He and Ar7+ - He collisions. E.Y. Kamber1, M.A. Abdallah2, C.L. Cocke and M. Stockli2. 1- Physics Department, Western Michigan University, Kalamazoo, MI 49008, USA. 2- J.R. Macdonald Laboratory, Kansas State University, Manhattan, KS 66506, USA. A high resolution Cold-Target Recoil-Ion Momentum Spectroscopy (COLTRIMS) has been used to study single-electron capture processes in collisions of Ar6+} and Ar7+ ions with He at laboratory impact energies between 9 and 300 keV. The energy-gain spectra indicate that the capture occurs into 4s and 4p states respectively for the ion charge states q = 6 and 7. Reaction channels associated with the population of core-excited projectile states are also observed in the Ar6+ - He collisions for the first time.