Some new effects seen in the passage of swift ion clusters through solids

Abstract

ARGONNE NATIONAL LABORATORY, ARGONNE, ILLINOISoperated under contract W-31-109-Eng-38 for she U. S. ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATIONDlSlKitiUiivJi'; 0;-lni^> u'ji/viiiiiii .iiVii i LD

Coulomb-explosion imaging ofCH2+: Target-polarization effects and bond-angle distribution

“…The preference for small values of cos ⌰ observed in the experimental P͑cos ⌰͒ distribution is well reflected by the dynamic simulation while it is absent in the static one. This aligning effect, which is due to the polarization forces dragging the protons into the wake of the carbon fragment, has been observed and discussed already in early experiments by Gemmell et al [7]. In contrast P͑⌽͒, which reflects the distribution of the projection of the molecular plane normal n onto the plane perpendicular to the beam direction, is as expected almost flat and independent of wake effects because of symmetry reasons; the only relevant feature in the P͑⌽͒ distribution is a dip at ⌽ Ϸ 0, which corresponds to a reduced detection efficiency for vertically aligned protons, which is well understood and reproduced by both simulations.…”

“…For a detailed understanding of the explosion process, a number of minor effects influencing the fragment trajectories have to be considered besides the dominant Coulomb repulsion. While most of these effects are well known and have been included in the standard data analysis procedure (such as multiple scattering and charge changing effects [3]), the dynamic polarization of the target material induced by the passage of the charged fragments (giving rise to the so called wake fields [4,5]) and its effect on the trajectories of neighboring fragments has never been fully integrated into the data reconstruction procedure; earlier measurements and simulations of dynamic polarization effects were performed only for diatomic molecular systems impinging on relatively thick targets [5][6][7].…”