[en] The cylindrically symmetric beam-foil collision produces excitation and alignment of atom and ion levels similar, but not identical, to that resulting at comparable energies from ion-atom or ion-molecule collisions. When the foil is tilted, the macroscopic change acts on the microscopic scale to produce coherent alignment and orientation of the excited levels. The maximum beam energy range bounding this interaction has not yet been defined. The dynamic interaction which produces these effects is currently not predicted by any theory, although the dynamics of the ions subsequent to the collision are well understood. Refinement of current experimental technique can be expected to better define the final foil surface. The beam-tilted-foil collision promises to be useful in the study of ionic structure via quantum beat, radio-frequency and level-crossing spectroscopy techniques, and may provide a useful probe for certain surface interactions. 4 figs, 48 refs

[en] The energies of photons obtainable from the VUV ring at the National Synchrotron Light Source (NSLS) are ideally suited for high-efficiency ionization of atomic outer-shell electrons. Given the high fluxes of photons available on a wiggler beam line, multiple photoionization in an ion trap can be easily achieved within times short compared to typical ion storage times in the trap. Measurements of the time evolution of ion populations in such a trap can yield ionic photoionization cross sections and charge-exchange interaction rates for ion-atom or ion-ion collisions. The various processes governing this time evolution are discussed and model calculations illustrating the relative importance of these processes under different conditions are presented. 8 refs., 5 figs., 1 tab

[en] The production and confinement of multi-charged ions in ion traps at electronvolt energies are described, as well as recent experiments in which ions are externally injected into Penning traps. Possibilities for cooling externally-injected ions are discussed. Electron transfer measurements using confined multi-charged ions are reviewed. 58 refs., 10 figs

[en] While high energy physicists have found it expedient to store ions at increasingly higher energies in devices of greater size and complexity, atomic physicists have generally attempted to store ions at ever lower energies, and often in miniaturized containers. However, many of the techniques used at both high and low energies are analogous or related. Three basic means of ion containment have been used: the dc electrostatic trap, the Penning-type trap with uniform magnetic field and quadrupole dc potential, and the radio-frequency quadrupole trap in either the cylindrically symmetric or storage-ring configurations. Each trapping configuration has characteristic advantages or drawbacks for particular measurements. Each method is described

[en] When keV to MeV energy ions are inelastically scattered from surfaces at near-grazing angles, the subsequent optical transitions of the projectiles are found to be highly circularly polarized, due to collisional orientation of the excited levels. This orientation increases linearly with ion velocity, at small velocities, and depends on the surface material. The magnitude of the orientation also depends on the concentration and type of gas adsorbed on the surface, and on some details of the absorption process. Measurements of the relative Stokes parameters for several transitions with the same core state, using different projectile charges, provides further information on the ion-surface interaction

[en] In a typical ion-atom collision, the cross sections for the population of magnetic substates having different absolute value m/sub j//values are not the same. When this condition exists, the state is said to be aligned, and radiation resulting from its subsequent decay is polarized and anisotropic. Therefore, an intriguing question is whether the observed nonstatistical intensity ratio in Ne recoil ions is just an artifact of the alignment of these states, or is it attributable to some other feature of the collision process. To provide an answer to the question posed above, the polarizations of the X rays emitted in the two transitions of interest were determined by using a crystal spectrometer as a polarimeter. Two spectra taken with parallel and perpendicular crystal orientations at a pressure of 5 torr are compared. (The spectra have been normalized so that the areas of the ¹P peaks are the same). The difference in the intensities of the ³P peaks at the two crystal orientations clearly indicates that polarization is present and that its effect is readily observable. However, it is obvious that alignment alone cannot account for the nonstatistical ¹P/³P intensity ratio. The ¹P/³P ratio depends on the pressure of the target gas due to the different quenching rates for these two states. Therefore, to investigate the population produced in the primary collision, the value of this ratio in the limit of zero pressure must be determined. The pressure dependence of the ¹P/³P intensity ratio measured in both crystal orientations is shown. The intensity ratio varies linearly with pressure over the range from 20 to 50 torr, however, below 20 torr large deviations from a linear pressure dependence were observed. The difference in the ratio at the two crystal orientations is independent of pressure

[en] Several beam-foil interaction theories predict specific dependences of the polarization of emitted light and of the excited level tensor parameters of the fast particles on the tilt-angle of the foil. Results of coherence measurements of the polarization of transitions from the 2p and 3p levels of Li, and the 4d ¹D level of He, excited at 60 keV incident ion energy, show both agreements with and deviations from particular theoretical predictions

No abstract available

[en] The recent extraction of ≅10⁴ ions per pulse with both high charge and high atomic number Z from the electron beam ion trap (EBIT) encourages consideration of methods for retrapping and cooling these ions to approximately 4 K. Anticipated stored ion densities near this temperature should result in the formation of crystalline arrays of these ions in the trap. Standard techniques for pulsed injection of ions into the trap, followed by resistive damping of the translational motion and collisional cooling with cold charged particles, are expected to optimize the cooling process. Expected ion storage times based on extrapolated electron transfer collision rates are favorable. Interesting potential measurements suited to cold, highly-charged ions are also discussed. (orig.)

[en] Molecular dynamics simulations are used to help design new experiments by modeling the cooling of small numbers of trapped multiply charged ions by Coulomb interactions with laser-cooled Be⁺ ions. A Verlet algorithm is used to integrate the equations of motion of two species of point ions interacting in an ideal Penning trap. We use a time step short enough to follow the cyclotron motion of the ions. Axial and radial temperatures for each species are saved periodically. Direct heating and cooling of each species in the simulation can be performed by periodically rescaling velocities. Of interest are Fe¹¹⁺ due to a EUV-optical double resonance for imaging and manipulating the ions, and Ca¹⁴⁺ since a ground state fine structure transition has a convenient wavelength in the tunable laser range