engleski

Projectile Z dependence of Cu K-shell vacancy production in 10-MeV/amu ion-solid collisions

The dependence of Cu (target atom) K-shell vacancy production cross sections on projectile atomic number was investigated in collision systems for which the ratio of projectile-to-target atomic numbers (Z1/Z2) ranged from 0.34 to 2.86. A combination of energy and wavelength dispersive x-ray spectrometry was used to measure Cu K x-ray production cross sections and to determine the appropriate fluorescence yields for converting them to K-vacancy production cross sections. The high-resolution spectra also revealed the presence of sizable contributions from predominately single-ionization mechanisms not directly associated with ion-atom interactions. The role of electron capture to the projectile was examined by observing the dependence of the cross sections on target thickness. The Cu K-vacancy production cross sections determined for equilibrated projectiles display a plateau centered in the region of symmetric collisions (Z1/Z2~1) and they become essentially constant beyond Z1 = 54. The cross sections for Z1>24 fall far below a (Z1)^2 scaling law and are greatly overestimated by the perturbed stationary-state theory with energy loss, Coulomb deflection, and relativistic corrections.

K-shell vacancy production cross sections; Cu target; dependence on projectile atomic number; K x-ray production cross sections

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