Recoil longitudinal momentum andQ-value measurements in electron-capture processes of fast multiply charged ions colliding with He

The recoil longitudinal momentum and Q value for electron capture with and without accompanying target ionization were measured for high-energy ${\mathrm{O}}^{7+}$-${\mathrm{F}}^{8+}$+He collisions using coincident recoil momentum spectroscopy. Electron capture into the projectile K shell and L-and-higher shells is separated in the recoil longitudinal momentum. The spectra for capture show that capture to the L and higher shells dominates at energies from 0.6 to 3.7 MeV/u while capture to the K shell increases with increasing collision energy. The relative contribution of capture to the K shell is consistent with theoretical expectation. Transfer ionization is compared with single capture within the independent-electron approximation. The results show that transfer ionization can be interpreted as being due to independent processes of capture and ionization.