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[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)

[en] Recently, anomalous population of capture nl sublevels of Kr³⁵⁺ ions emerging from thin solid foils has been reported (1). This effect was tentatively interpreted on the basis of a Stark mixing in the wake electric field of the moving ion (≅ 10⁹V/cm for 35 Mev/u Kr³⁵⁺ ions in C). Such a field has been quantitatively observed in a plasma source. However, in solid medium, only partial evidence of this phenomenon has been given, through experiments on molecular dissociation and energy splitting of excited states of ions in solids. In any case a possible modification of collisional processes in solids by a wake electric field has to be investigated. Some outcomes have been identified for testing; these include, among other effects, a difference of the polarization of the light emitted by ions emerging from gaseous or solid targets. The authors have measured the angular distributions 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-X-rays emitted by projectiles after capture have been extracted from the best fit of their measured angular distributions. They note a good agreement between experimental and theoretical values in the case of gas targets. On the other hand a definite solid-gas difference is observed. These differences in relative intensities and polarization of Lyman transitions can be qualitatively explained by a wake electric field-induced Stark mixing of excited sublevels

[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] For high velocity collisions, Doubly Differential Cross Sections for target ionisation (the main primary process), are well described by a recent refined theory. This allows ab initio calculation of the structure of the energy deposition in the incident ion track. Such a calculation first developed for radiobiological purpose has been applied to the case of a silicium target. Charge density profiles for various ions are presented here

[en] The angular distribution of the 2P → 1 S transitions following electron capture of 35 MeV/u Kr³⁶⁺ ions was measured in neon, argon, carbon, silicon and copper targets. Very thin solid targets were used for insuring single collision conditions. Polarizations of the Lyman alpha-X rays emitted by projectiles after capture were calculated from the best fit of their measured angular distributions. Theoretical polarizations of Lyman alpha lines including cascade contribution are also reported

[en] The objectives, techniques and results of studies of state to state charge transfer in gas are reviewed. Then some experiments about ions in solids which tend to indicate a possible role of the solid medium in the production of projectile excited states are described

[en] In order to assess the lethal efficiency and other biological effects of inner shell ionisations of constituent atoms of DNA ('K' events), experiments were developed at the LURE synchrotron facility using ultrasoft X rays as a probe of K events. The lethal efficiency of ultrasoft X rays above the carbon K threshold was especially investigated using V79 cells and compared with their efficiency to induce double strand breaks in dry plasmid-DNA. A correlation between the K event efficiencies for these processes is shown. Beams of 340 eV were found to be twice as efficient at killing cells than were beams at 250 eV. In addition, a rough two-fold increase of the relative biological effectiveness for dicentric+ring induction has also been observed between 250 and 340 eV radiations. (author)

[en] Target thickness dependence measurements of Lyman x-ray emission cross sections in collisions of 33 MeV u^-1 Kr³⁶⁺ ions with C, Al and Cu target have been performed. Our results have been compared with the predictions of a rate-equation model including the nl-nl' process. The needed intrashell excitation cross sections have been calculated for 2≤n≤10 in the plane-wave Born approximation with screening and antiscreening effects accounted for. Using these cross sections, poor agreement with experiment is obtained. On the other hand, a set of fitted l-changing cross sections can be found to reproduce our data. These last cross sections are a factor 3-50 larger than the calculated ones. We believe this discrepancy to be an indication of a specific effect of free (or quasi-free) electrons in solid targets. (author)

[en] Theoretical models for low energy charge exchange collisions of highly charged ions are reviewed in connection with population final states. A simple experimental method is presented which provides the most populated n level, the percentage of p substates and the mean l value. Results are reported for 10 keV/q Al¹²⁺ collisions on H₂ and He. (orig.)