[en] Whereas biological studies indicate that double strand breaks in DNA are responsible for cellular death induced by radiations, the physical processes generating such events are not known. For this reason, good parameters to quantify radiation effects are not yet available. In general, no direct relationship is found between the rate of biological damage and the radiation linear energy transfer (LET). This phenomenon may look paradoxal: the lethal efficiency of ions sometimes decreases when the ion LET increases exclamation point Recent interpretations of this effect rely on the characteristics of the energy deposit at the microscopical scale. Whereas energy deposits of 100 eV in 2 nm cubes overlapping DNA are sometimes quoted as critical, here is emphasized a possible dominant role of ion induced K-vacancies in C-atoms of DNA. The existence of a strong correlation between calculated K-vacancy cross sections (ionization + capture) and experimental cell-inactivation cross sections is pointed out and discussed

[en] The process of single and double electron transfer from target K to projectile K or excited state is discussed for collisions in the high and intermediate velocity range. A description is given for the concepts underlying different theoretical models and recent detailed experimental results are presented

[en] Coincidence measurements between O⁶⁺(3,3), (3,4) (or (4,4)) ions and their emitted x-rays have been performed in double capture collisions between fully stripped O⁸⁺ ions and He (or H₂) targets at 1.24 keV amu^-1. Average ratios of autoionization widths towards different continuum states have been extracted from this measurement and compared with predictions of new Feshbach calculations. A complete set of theoretical partial autoionization widths for the singlet (3,3), (3,4) and (4,4) states of O⁶⁺ is also given. In most cases our results exclude a dominant population of high-L states by double capture in contrast with previously reported measurements at higher velocities. (author)

[en] Relative intensities of Lyman x-rays due to one- or two-electron capture have been measured for collisions of 4 keV u^-1 Al¹³⁺, Al¹²⁺, Ne⁹⁺ ions with He and H₂ targets. A method is presented to extract separate information on single and double transfer processes. Preferential n states, proportion of p substates and mean l values populated by single capture are measured, together with double capture probabilities. Comparison of experimental results with theoretical predictions for one-electron systems with near-crossing radii suggests that the location of these crossings may be more important than target internal structure to determine final l distributions. (author)

No abstract available

[en] Changes in the mean state of L-shell ionisation have been observed when 300 MeV Kr²⁰⁺ ions traverse foil targets of varying thicknesses. The influence of related effects on K x-ray yield variation with target thickness is examined; in particular, K-hole lifetime and fluorescence yield modifications inside the target as well as a possible variation of the K-vacancy production cross section are considered. A new model is proposed which shows how to extract K-shell ionisation and capture cross sections when these effects are taken into account. It is also seen that such experimental studies can lead to a new information about the ionisation of the 2pπ MO during a collision. (author)

[en] The probability of double K-vacancy production accompanying nuclear electron capture in ²⁰⁷Bi has been measured and found to be Psub(KK)=(6+-2.5)x10^-6, and compared with the double K-vacancy production during internal conversion of neighbouring atoms and various theoretical models. It is found that correlation effects drastically change the probabilities which may be derived from the central field approximation. (author)

No abstract available

[en] Recently an anomalous population of capture nl sublevels of Kr³⁵⁺ ions emerging from thin solid foils have been reported. This effect was tentatively interpreted on the basis of the Stark effect in the electric field in the wake of the moving ion. Such a field has been quantitatively observed in a plasma source. However, in solids, only partial evidence of this phenomenon has been obtained. A well known drawback of experimental studies with solid targets is the multicollision effect. We have shown from theoretical grounds that the single collision condition is fulfilled for deepest ionic states when working with the fast heavy ions. Indeed mean free paths for the most probable process, nl' excitation, are many times larger than the target thicknesses used. We have measured the angular distribution of the 2P → 1S transition following electron capture of 35 Mev/u Kr³⁶⁺ ions in various gaseous and solid media. Polarizations of the Lyman α-Xrays emitted by projectiles after capture have been extracted from the best fit of their measured angular distributions. A good agreement is found between the experimental results and theoretical calculations for gas targets, but not for solids. (author)

[en] The bare heavy ions or one electron ions Fesup(26+,25+), Krsup(36+,35+), Usup(92+,91+) given by the new accelerators of nuclear physics constitute a privilegiated tool in atom collision study because they allow for the first time to realize pure three-body problems. For many years, development of experiments using multicharged heavy ions and multiple scattering have greatly improved our high velocity collision phenomena understanding and our ability to realize quantitative predictions