The procedure of calibration of the detector assembly consisting of the two Galileo microchannel plates (MCPs) operated in a chevron configuration is described. The current gains and the analog particle gains of MCPs for Xe ions with charge states from q=3+ to q=13+ and C ions, with charge states from q=1+ to q=6+ and ion impact energies to charge state ratios from 0.5 to 150 keV/q have been measured. These results were compared to the earlier results obtained of calibration of this detector assembly with Xe ions with the charge states from q=7+ to q=43+ and ion impact energies to charge state ratios from 2 to 154 keV/q. We have shown the areas of ion parameters in which the secondary ion-electron emission coefficient of the investigated MCPs was dominated by kinetic or potential emission.

The Kansas State University cryogenic electron beam ion source supplies low energy ion beams to users of the Department of Energy user facility for highly charged ions. The ions escape the source with an initial energy between 1.6 and 5 kV per charge and are analyzed in a 90° dipole magnet located on the high voltage platform. When leaving the platform the ions can be accelerated by up to 160 kV per charge or can be decelerated to about 20% of their initial energy, covering 2.5 orders of magnitude. We are in the process of adding another order of magnitude to the range of available ion energies as a newly installed lens allows for deceleration down to a very few percent of the initial energy. In addition we present the current microbunching and chopping system which has been substantially improved over the past 2 yr.

The work presents results of absolute measurements of the energy distribution of ions, the ion current density, and the number of ions emitted from a tantalum laser-produced plasma. The results were obtained using two types of calibrated windowless electron multipliers. The number of ions with the individual charge state in the range z=37–42 was about 2.5×108 ions/cm2 and the maximum ion current density was about 0.5 mA/cm2 at the distance of 174 cm from the target. Moreover, the ion signals, the one measured by means of an ion collector and that reconstructed on the basis of measurements performed with an electrostatic ion energy analyzer, are also compared as well the influence of the secondary electron emission effect on the ion collector signal applied in the experiment is estimated.

Experimental measurements of the projectile angular distributions for 2.5-keV Ar{sup 8+} ions capturing one to five electrons from a gas-phase C{sub 60} target are presented. The number of captured electrons was determined by demanding a coincidence between the scattered projectile and a charge-state-analyzed intact C{sub 60} recoil ion. The results are compared to calculations based on a dynamical classical overbarrier model. Good agreement is obtained only if the influence on the projectile trajectory by the large polarizability of the C{sub 60} target is taken into account, thereby making the collective dielectric response of the cluster target observable in a scattering experiment. {copyright} {ital 1998} {ital The American Physical Society}

Experimental measurements of the projectile angular distributions for 2.5-keV Ar8+ ions capturing one to five electrons from a gas-phase C-60 target are presented. The number of captured electrons was determined by demanding a coincidence between the scattered projectile and a charge-state-analyzed intact C-60 recoil ion. The results are compared to calculations based on a dynamical classical overbarrier model. Good agreement is obtained only if the influence on the projectile trajectory by the large polarizability of the C-60 target is taken into account, thereby making the collective dielectric response of the cluster target observable in a scattering experiment. [S1050-2947(98)08108-6].

The procedure of calibration of the detector assembly consisting of the two Galileo micro channel plates (MCPs) operated in a Chevron configuration is described. The current gains and the analog particle gains of the MCPs for Xe ions with charge states from q=7+ to q=43+ and ion impact energies to charge state ratios from 2 keV/q to 154 keV/q have been measured. For the investigated range of ion impact energies we have stated that for xenon charge states of q=7+ up to q=15+ the secondary ion-electron emission coefficient is dominated by kinetic emission of electrons. Potential effects start to be visible for charge states above q=151.

Experimental measurements of the projectile angular distributions for 2.5-keV Ar{sup 8+} ions capturing one to five electrons from a gas-phase C{sub 60} target are presented. The number of captured electrons was determined by demanding a coincidence between the scattered projectile and a charge-state-analyzed intact C{sub 60} recoil ion. The results are compared to calculations based on a dynamical classical overbarrier model. Good agreement is obtained only if the influence on the projectile trajectory by the large polarizability of the C{sub 60} target is taken into account, thereby making the collective dielectric response of the cluster target observable in a scattering experiment. {copyright} {ital 1998} {ital The American Physical Society}

Contributions of the electron-electron and electron-nucleus interactions to the ionization of O7+ by He are experimentally separated using recoil momentum spectroscopy. The electron-electron contribution is found to produce much smaller recoil momenta, both longitudinal and transverse. The momentum distributions of the two mechanisms are in good agreement with theoretical predictions. The comparison between the experiment and the theory suggests that electron-electron interactions in the projectile ionization can be understood in terms of free-electron impact ionization of the projectile ions.

A technique for electron spectroscopy which yields full two-dimensional momentum distributions for continuum electrons has been used to study ejected electrons from single ionization of lie by C6+ and proton projectiles at low velocities. Projectile velocities of 1.63, 1.38, and 1.16 a.u, for C6+ and 2.39, 1.71, 1.15, .85, and 0.63 a.u. for protons were used. All spectra show much broader distributions along the beam than transverse to the beam. For the case of proton bombardment, the spectra are strongly influenced by both target and projectile potentials, maximizing near the velocity of the saddle in the potential between the two, receding ion cores for the lowest projectile velocities. For C6+ projectiles, the spectra appear to be dominated by the projectile potential and the center of the distribution is strongly shifted toward the projectile velocity. Theoretical results from the continuum-distorted-wave-eikonal-initial state and classical-trajectory-Monte Carlo methods are in rather good agreement with the proton data but do not agree well with the C6+ data.

The KSU-CRYEBIS, a CRYogenic electron beam ion source, supplies experiments with low-energy, highly charged ions of numerous species. The supplied charge states cover the range from 1+ to 52+, with typical beam currents of a nA for low charge states and a few pA for the highest charge states. The ion energies cover the range from 0.3 to 165 keV per charge. This is an unusually broad range of final ion energies and hence requires an unusual dynamic ion transport system. This paper presents advances made with respect to the CRYEBIS ion beam transport, diagnostics, and identification. In addition, an update on the developments of ion beams with very high duty cycles is given.

The method of 0° electron spectroscopy was used to study binary encounter electrons resulting from hard collisions between 1.5 MeV/u C6+ ions and the electrons in a C60 vapor target. The Compton profile of C60 was then extracted from the electron spectra using an impulse approximation treatment. The experimental results are in excellent agreement with theoretical Compton profiles of C60. The C60 Compton profile is compared with that of atomic carbon, as well as those for graphite and diamond.

Cross sections and fragmentation mass spectra have been measured for the capture of electrons from C60 by slow Ar8+ ions. Two mechanisms are identified: For large impact parameters multiply charged C60 (up to 6+) ions are produced, while for smaller impact parameters the C60 is broken into smaller fragment ions. The absolute cross sections are consistent with an over-barrier picture for long range capture, while the destruction cross sections are round to be somewhat larger than the geometrical C60 cross section.

A charge-transfer experiment has been done in which 63-keV ${\mathrm{Ar}}^{7+}$ was incident on sodium in the ground and first excited states. The electron-capture ratio \ensuremath{\sigma}(Na(3p))/\ensuremath{\sigma}(Na(3s)) was experimentally determined for this system. The charge-capture cross section was observed to increase by a factor of 1.5 for the excited target.

We have investigated collisions of Ar8+ and Xe14+ with Buckyballs C60 at energies of 10 keV/q. Multiply charged Cq+60 up to q=6 are observed in collisions for which the projectile keeps only one or two electrons. Catastrophic destruction of the C60, signalled by production of light C+n fragments, is accompanied by the production of projectiles whose charge state is substantially reduced.

Electron capture by Ar{sup 8+} (80 keV) projectile from a C{sub 60}/C{sub 70} vapor target have been investigated. The absolute cross sections for the projectile keeping 1 to 7 electrons have been measured. The target was produced by heating a {approximately}80% C{sub 60}, 20% C{sub 70} mixture in a resistively heated oven. The projectile beam was electrostatically charge state analyzed and detected with a position sensitive detector. The measured cross section will be compared with predictions of the classical over-barrier model.

A charge-transfer experiment has been done in which Ar 7+ was incident on sodium in the ground state and first excited state. Absolute capture cross sections were determined for projectile velocities in the range of 0.1-1.0 a.u. The experimental findings are compared with the results of semiclassical calculations