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Cross-section ratios sigma(TI)/sigma(SC) of transfer ionization (TI) to single capture (SC) of Cq+- and Oq+-He (q = 1 - 3) collisions in the energy range of 15-440 keV/u (0.8-4.2 v(Bohr)) are experimentally determined. It is shown that sigma(TI)/sigma(SC) strongly depends on the projectile velocity, and there is a maximum for E(keV/u)/q(1/2) approximate to 150. Combining the Bohr-Lindhard model and the statistical model, a theoretical estimate is presented, in reasonable agreement with the experimental data when E(keV/u)/q(1/2) > 35.

The ratios of transfer ionization (TI) to single-electron capture (SC) cross sections have been measured for the collisions of partially stripped Cq+ ions (q = 1-4) with He. The collision velocity ranges from 0.7 to 4.4v(0) (v(0) is the Bohr velocity). The projectile-ion and recoil-ion coincidence technique is used to separate the processes of TI and SC. The ratios reach the maximum when the velocity is about 3.7 v(0). This can be explained qualitatively based on the two-step mechanism. The experimental results are also compared with the results calculated using the classical trajectory Monte Carlo (CTMC) method. The CTMC results are in agreement with the experimental data basically. The discrepancies in higher velocity region are interpreted by the effective charge effect.

In this paper we report the measurements of the K x-ray relative transition probabilities as follows: K-beta/K-alpha for the atomic numbers Z = 39, 51, 62, 63, 64, 66, 67 and 68; and K-alpha2/k(alpha1), k(beta1)(1)/k(alpha1), k(beta2)(1)/k(beta1)1, and k(beta3)/k(beta2) for the atomic numbers Z = 62, 63, 64, 66, 67 and 68 as induced by protons at an energy of 3 MeV. The experimental results obtained are then compared with relativistic Hartree-Fock calculations.

A simple model for the direct ionization and transfer ionization probabilities in A2+ +He collisions in a wide projectile energy range is proposed based on the Bohr–Lindhard model and the classical statistical model. The calculated cross sections are in satisfactory agreement with the experimental data available.

The multi-electron processes are investigated for 17.9–120 keV/u C1+, 30–323 keV/u C2+, 120–438 keV/u C3+, 287–480 keV/u C4+ incident on a helium target. The cross-section ratios of double electron (DE) process to the total of the single electron (SE) and the double electron process (i.e. SE+DE), the direct double electron (DDI) to the direct single ionization (DSI) as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.

The cross section ratios of the double, triple and quadruplicate ionization to the single ionization of argon by 1.5-7.5 MeV partially stripped carbon ions are measured by using time-of-flight technique. The Auger transition and the charge exchange process in the multiple ionization of argon are studied. The ratios of cross sections of the direct multiple ionization to those of the direct single ionization are obtained by subtracting the parts of the Auger transition and the charge exchange process from the measured data. It is found that the cross section ratios of the direct multiple ionization to those of the direct single ionization are in good agreement with the predicted multi-step (ν/qeff)-2n+2 law.

The classical method within the independent electron model is employed to investigate (i) charge dependences of single and double ionization for helium by various charged ions Aq+ (q = 1 – 8) at impact energies of 0.64 and 1.44MeV/u, respectively, (ii) energy dependences of transfer ionization for helium by 0.5–3 MeV/u A8,9+ ions impact. The Lenz–Jensen model of the atom is applied instead of the Bohr model of the atom, and the impact-parameter dependences are also introduced into the calculations. Satisfactory agreement is found between theoretical and experimental data.