B. Skogvall

Double ionization of Li by 95 MeV/u N7+ impact

For collisions of N7+ and Ne10+ on He and N7+ on Li at an incident energies of 95 MeV/u, the cross‐section ratios for double to single ionization of the target is determined experimentally. For N7+ +Li, comparisons between measurements and calculations of shake‐off in the sudden approximation are made. Deviations by a factor of 30 are found between measurements and calculations. For Ne10+ +He and N7+ +He, the measured cross‐section ratios are compared with previous measurements using protons on He, and a ZP‐dependence is determined.

Angular and high-frequency analysis of electron interference structures in {approx}60 MeV/u Kr{sup 34+}+H{sub 2} collisions

Detailed analyses of previous measurements, combined with additional measurements reported here, have been made of electron interference structures observed in 60 MeV/u Kr34+ + H2 collisions. Results are used to characterize the angular dependence of the primary interference structures over a wide range of electron ejection angles, particularly backward angles, and, additionally, to search for high-frequency structures as reported recently for 1–5 MeV/u H+ + H2 collisions [Hossain et al., Phys. Rev. A 72, 010701(R) (2005)]. The data for backward ejection angles, in combination with earlier data, permit a detailed comparison with theory over the range 30°–150°, showing that none of the existing theories predict accurately the observed oscillation frequencies for backward angles. Electron spectra for 90° and 150° taken in small energy steps and with improved statistics compared to earlier measurements were examined by means of a Fourier analysis but no evidence of the high-frequency structures reported for H+ + H2 collisions was found.

Two- and three-body effects in fast ion-atom collisions: Analogies between photon and charged particle impact

Two- and three-body effects in the emission of low-energy electrons from atomic Li by fast (95 MeV/u) Ar18+ projectiles are identified and separated experimentally. Cross sections for single electron emission have been measured for electron energies ranging from 3 to 1000 eV and angles ranging from 25° to 155°. Models based on the Born approximation are introduced to separate two- and three-body effects in the angular distributions of the ejected electrons. The two- and three-body processes are associated with Compton scattering and photoabsorption, respectively. Both the high projectile velocity and the use of the Li target are shown to be essential for performing the present analysis. The emission of the 1s electron is attributed mainly to three-body effects. The cross section for three-body processes rapidly decreases with the electronic energy transfer, in accordance with estimations based on the photoabsorption cross sections. Remarkably large contributions from two-body collisions for the low-energy...

Ionization of Li by fast highly charged ion impact

Abstract Angular distributions of ejected electrons in fast N 7+ + Li collisions have been measured. By calculating the individual amplitudes in a multipole expansion, we evaluate the relative importance of dipole transitions. Using a Li target, we find the relative importance of dipole transitions to depend strongly on the initial state.