Projectile Charge Dependence of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>-Shell Ionization by Swift Light Nuclei

Abstract

$K$-shell x-ray yields were measured for Al and Ni bombarded by H, D, He, and Li of kinetic energies between 1 and 7.5 MeV/amu. Ratios of $K$-shell ionization cross sections for projectiles of different atomic numbers ${Z}_{1}$, at equal velocities, show pronounced deviations from the $Z_{1}^{}{}_{}{}^{2}$ dependence predicted in the plane-wave Born approximation. The effect can be understood in terms of distortions of the $K$ shell in the field of the ionizing particles.