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X-ray spectra of K-shell hollow krypton atoms produced in single collisions with 52 - 197 MeV/u Xe54+ ions are measured in a heavy-ion storage ring equipped with an internal gas-jet target. Energy shifts of the K{\alpha}_1,2^s, K{\alpha}_1,2^(h,s), and K\b{eta}_1,3^s transitions are obtained. Thus, the average number of the spectator L-vacancies presented during the x-ray emission is deduced. From the relative intensities of the K{\alpha}_1,2^s and K{\alpha}_1,2^(h,s) transitions, the ratio of K-shell hollow krypton to singly K-shell ionized atoms is determined to be 14 - 24%. In the considered collisions, the K-vacancies are mainly created by the direct ionization which cannot be calculated within the perturbation descriptions. The experimental results are compared with a relativistic coupled channel calculation performed within the independent particle approximation., Comment: 5 figures, 9 pages. Accepted by Physical Review A

Nb L-shell ionization cross sections induced by Xeq+ (12 ≤ q ≤ 29) ions were measured as a function of the incident charge state q in the energy ranging from 1500 to 2500 keV. In this experiment, w...

L-shell x-ray yields of molybdenum bombarded by highly charged Arq+ ions (q = 11-16) are measured. The x-ray production cross-sections are extracted from the yields data. The energy of the incident Ar ions ranges from 200 to 350 keV. After the binding energy correction, experimental data are explained in the framework of binary-encounter-approximation (BEA). The direct ionization is treated in the united atom (UA) limit (Lapicki and Lichten 1985 Phys. Rev. A 31 1354), not in the separate atom (SA) limit. The calculation results of BEA (Gacia and Fortner 1973 Rev. Mod. Phys. 45 111) are much lower than the experimental results, while the results of binding energy modified BEA are basically in agreement with the experimental results.

The cross-section ratios R of transfer ionization to single electron capture of Helium atom induced by fluorine ions in the strong-interaction region were measured by means of the position-sensitive-detection and the time-of-flight (TOF) technologies. The velocity and charge state dependence of R were studied. It is found that the R decreases when the 2q/v increases, where q and v are the charge state and velocity of projectile respectively. In this energy region the transfer ionization can be look as Two-Step process that one target electron is captured, and another electron is ionized.

The spectra of highly charged titanium ions produced by the interaction of 120 MeV titanium ions with carbon foil were investigated with the so-called beam-foil technique using the HI-13 tandem accelerator in China Institute of Atomic Energy. Spectral lines emitted from fifty-three excited energy levels were observed in the wavelength range 120–220 A, among which eleven lines were new. Our experimental results show good agreement with the results of laser plasma experiments, and are in reasonable agreement with theoretical calculations.

The excitation spectra in the wavelength range of 19—40 nm for highly ionized sulphur ions were measured by using the beam-foil method at the Heavy lon Research Facility in Lanzhou. In this experiment, more than 30 spectral lines were observed, which belonged to the transitions of the excitation energy levels for highly ionized SX—SXV ions, and 5 new lines were determined. The experimental results were compared with those from other experiments and theoretical calculations.

We report studies on both target and projectile K-shell ionization by collisions of Cu9+ ions on the thin Zn target in the energy range of 60–100 MeV. In this work, the relative ratio for the production of the target to projectile K-vacancy is measured. The result shows that it almost remains stable over this energy range and has good consistency with the predictions by vacancy transfer via the 2pσ–1sσ rotational coupling, which gives experimental evidence for K-vacancy sharing between two partners. Furthermore, the discussion for comparisons between the experimental ionization cross sections and the possible theoretical estimations is presented. These comparisons suggest that the experimental data agree well with those predicted by the Binary–Encounter approximation (BEA) model but are not in good agreement with the modified BEA calculations. It allows us to infer that the direct ionization (and/or excitation) is of importance to initial K-vacancy production before 2pσ–1sσ transitions in the present collision condition.

Multiple ionization in collisions of 170 MeV S9+ ions on Ar target atoms was investigated by using time-of-flight (TOF) technique. The charge state distribution of the recoil ions produced in the collisions were determined by the coincident TOF between the projectiles and the recoil ions. The relative recoil ion productions were extracted and compared with the theoretical calculations of n-body classical trajectory Monte Carlo methods.

We report beam-foil measurements of the spectrum for Ar II. Totally 56 lines are measured. Most of them are mainly ascribed to 3d-4p, 4s-4p, 4p-4d and 4p-5s resonance transitions. These spectral lines are identified, among which 16 lines are new and accurately measured. Analyses of the spectra are based on a comparison with the other experimental results and calculated values.

Multiple electron transfer processes are studied for Arq++Ne (q=8, 9, 11, 12) collisions by using multi-parameter coincidence techniques. Various electron transfer processes are identified experimentally and the related cross-sections are measured. The dependence of transfer ionization cross-sections on the recoil charge states is compared with the results from the modified molecular classical overbarrier model. It is found that the modified model described the experimental results reasonably.

Electron Capture and transfer ionization by Ar(8–12)+ in collisions with argon atoms were studied by using the position sensitive and time-of-flight techniques. Some of the measured projectile charge changing cross sections (σq,q−k) and phenomenological cross sections (σrq,q−k) are reported in this paper. The measured cross sections are compared with the predictions of the molecular Coulombic overbarrier model by considering the autoionization decay and electron evaporation of multiply excited states in projectiles and recoil ions respectively.