Differential cross sections for K-shell ionisation and capture in asymmetric collisions: scaling properties

Abstract

Target K-shell ionisation and K-shell capture cross sections differential in projectile scattering angle have been measured for selected combinations of accelerated 1H, 4He and 7Li ions and gaseous targets of neon and argon. The K-shell vacancy producing events were identified by scattered-particle, KLL Auger electron coincidence techniques. The choice of projectile-target combinations has resulted in a set of data illustrating for fully stripped projectiles, the dependence of the K-shell processes on projectile atomic number Z1 and target atomic number Z2 at a fixed collision velocity nu , measured relative to the orbital velocity of the K-shell electron nu K ( nu / nu K approximately=0.46). Further, in view of theoretical predictions, the selection is aimed in particular at forming groups of data with approximately constant Z1/Z2 ratios. In one case, He to Ne, the authors also studied the K-shell ionisation process (i) for projectiles carrying electrons, to test for a possible charge state effect, and (ii) for faster, fully stripped projectiles ( nu / nu K approximately=0.8). The authors also present measurements of impact-parameter-dependent, total capture probabilities.