X-Ray Emission from Slow Highly Charged Ar Ions Interacting with a Ge Surface

We have measured K x-ray spectra and yields from Ar17+ ions slowly approaching a single-crystal Ge surface. The yields were measured as a function of the projectile velocity component perpendicular to the surface. From the data a characteristic time of approximately 1 psec was extracted for the in-flight filling above the surface of the Ar K vacancy

Differential Transfer Ionization Cross Sections for 50175-keV Proton-Helium Collisions

We have measured coincidences between neutralized projectiles and He recoil ions for 50175-keV proton-helium collisions. From the data we obtained transfer ionization (TI) cross sections differential in the projectile scattering angle. Laboratory scattering angles range from 0 to 2.0 mrad. The experimental method allowed separation of the postcollision charge states of the target atoms. The ratio of the cross sections for TI to the sum of TI and single capture, F, is presented as a function of projectile scattering angle. Comparison is made to previous measurements of this ratio where data is available. The differential cross sections are compared to dynamical classical trajectory Monte Carlo (dCTMC) calculations. Agreement in the shape of the differential cross sections is good between the theory and measurement over the entire energy range

State Selective Scattering Angle Dependent Capture Cross Sections Measured by Cold Target Recoil Ion Momentum Spectroscopy

We have developed a new kind of recoil ion momentum spectroscopy technique, using a precooled supersonic gas jet target, to determine state selective, scattering angle dependent cross sections for swift ion-atom collisions ( 0. 25 , ..., , 1 MeV He2+ on He), by measuring the transverse and longitudinal momentum of the recoil ion. A longitudinal momentum resolution of ± 0.13 a. u. was achieved, about a factor of 30 better than ever obtained before, which enables a clear separation of K and L shell capture. In the transverse direction a resolution corresponding to a projectile scattering angle uncertainty of Δ ϑ P = ±1 μ rad was obtained

K X-Ray and Auger Emission from H-like Ar Ions Slowly Approaching a Ge Surface

We have studied K x-ray and Auger emission from Ar17+ ions interacting with a Ge surface. The x-ray yields were studied as a function of the vertical projectile velocity with respect to the surface. © 1991 Springer-Verlag

Interference in K-K Transfer Investigated with Decelerated H-like S Beams

The K-shell to K-shell vacancy transfer probability has been investigated as function of impact parameter for low energy S15+ -Ar collisions by measuring S and Ar K X-ray particle coincidences. The slow H-like S-beams were obtained by post-stripping S8+ at 108 MeV and then decelerating with the Heidelberg RF linac. With such beams, oscillating Ar K-vacancy probabilities as a function of impact parameter were found. The structure is interpreted as constructive and destructive interference of the transfer amplitudes on incoming and outgoing parts of the collision trajectory

Interference Effects in K Vacancy Transfer of Hydrogenlike S Ions Colliding with Ar

The impact-parameter-dependent K-shell to K-shell vacancy transfer probability has been investigated for 4.7, 7.9, 16, 32 and 90 MeV S 15+-Ar collisions by measuring S and Ar K X-ray particle coincidences. With low-energy H-like S beams (obtained by poststripping S at 108 MeV and decelerating with the Heidelberg RF linac), oscillating Ar K vacancy probabilities as a function of impact parameter were measured. This structure can be interpreted as constructive and destructive interference of the transfer amplitudes on incoming and outgoing parts of the trajectory. Thus measurement of the height as well as the phase of the coupling amplitude allows for a very sensitive test of different coupling models. The interference maxima and minima could be related to values of the phase integral over the 2 p sigma -1 s sigma energy difference from which information about this energy difference could be obtained

Recent Experiments on the KSU CRYEBIS

The CRYEBIS at KSU is in operation since the spring of 1989. The experimental efforts undertaken since then were focused on two projects: In one the interaction of the produced ions with the electron beam in the source is studied. In the second project the ions are extracted from the source and the interaction with a solid surface is investigated. Here we report on first results of these experiments

Impact-Parameter Dependent L-K Vacancy-Transfer in Collisions of Ni²³⁺ with Ge Solid Targets

Using a particle-photon coincidence technique, we have measured the influence of the solid target preparation and thickness on the target K-vacancy production probability (PK(b)) in collisions of 3.6 MeV/u Ni23+ with Ge. The probabilities were measured as a function of the impact parameter b which is calculated from the projectile scattering angle using a screened Bohr-type potential. For target thicknesses varying by more than a factor of 100, no change in the shape of the PK(b) curve was found. Even the data obtained with implanted Ge targets (≈ 1 x 1016atoms cm-2), used for the first time in an L-K vacancy-transfer experiment, showed the typical solid target behaviour with the adiabatic peak being shifted towards smaller impact parameters

Full Scale Relativistic Ab Initio Time Dependent Calculations for the L-K Vacancy Transfer in 208 MeV Ni²³⁺ on a Ge Solid Target

We present full scale ab initio relativistic calculations for the L-K vacancy transfer in collisions of 208 MeV Ni23+ on a Ge solid target. Our Dirac-Fock-Slater method allows us to achieve a very accurate quantitative explanation for the experimental impact parameter-dependent vacancy probabilities in terms of dynamic creation and annihilation of Ni n = 2 shell vacancies

Spectroscopy of Quasimolecular X-Rays with H-like Decelerated Ions

The quasimolecular 2pπ-1sσ transition energy as a function of the internuclear distance is obtained from the interference structure observed in quasimolecular K X-ray spectra from low energy H-like projectiles measured at certain impact parameters