W. Waggoner

Angular distributions of reaction products from low energy capture by multicharged ions

Abstract The angular deflection of the projectile which occurs when a slow multiply charged ion captures electrons from a neutral target depends sensitively on the potential curve history of the interaction throughout the encounter. We have measured angular distributions for a variety of projectiles capturing from targets of He, Ar and d2. Some of the major features may be understood in terms of classical deflection functions for the heavy particle motion. Where quantal treatments of the scattering is available, the calculations are in good agreement with the data.

Angular distributions of slow multiply charged ions following capture

Abstract When slow, multiply charged projectiles capture electrons from neutral targets, the angular distributions of the capturing particles are much more sensitive to the potential curves involved than are the total cross sections. We have constructed an apparatus suitable for measuring angular distributions of these capture products. A position sensitive channel plate chevron followed by a resistive anode is used to determine the scattering angle and a simple retarding grid system is used to select the final charge states. Multiply charged projectiles are obtained from recoil ion sources pumped by fast ion beams from the KSU tandem accelerator. Systems studied include Neq+, Cq+ and Arq+, with q lying between 3 and 8, on targets of He, D2 and Ar at accelerating v and 350 V. Selected cases will be presented and discussed.

An experimental apparatus for studying double differential scattering by low energy Xq+ ions from He

Abstract A new differential energy gain spectrometer has been constructed and tested for the study of the double differential cross section, in energy and angle, for state selective electron capture processes of low energy multiply-charged ions with atomic gases. Translational energy spectra for single electron capture by N2+ and O2+ colliding with He has been measured in the impact energy range 60–200 eV and scattering angles between 0° and 4°. In these collision systems, the dominant processes observed are due to capture into the ground state (2p23P) of N+ and the metastable state (2p32P) of O+, respectively.

Electron capture studied by a time-of-flight technique

Abstract A time-of-flight spectrometer capable of measuring simultaneously scattering angle and energy of reaction products from collisions between multiply charged ions and neutral targets is described. The apparatus has been used to investigate the collision system Ar q + + Ar at an energy of 52.2 q eV. The angular distribution of the reaction products is found to be different for singl capture and transfer-ionization.

An experimental apparatus for translational energy spectroscopy for low energy Xq+ on atomic hydrogen

Abstract The design and performance of a system for performing translational energy spectroscopy on atomic hydrogen targets is presented. Low energy highly-charged ions are produced in a recoil ion source through collisions between target gases and a heavy, fast pump beam from the EN tandem accelerator. These ions are directed through a double-focusing magnetic spectrometer which selects the desired projectile charge state. An atomic hydrogen target is produced in a thermal dissociation oven. The energy and final charge states of the product ions are determined by a double-focusing, hemispherical electrostatic analyzer. The current work concentrates on the change in energy of the projectile ions accompanying electron capture for 250 eV per charge argon projectiles.