Dependence of Argon<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>-Shell Ionization on the Charge of Bare Nuclei at 1 to 2 MeV/amu

Abstract

Argon $K$-shell ionization cross sections have been determined from x-ray yields measured in single collisions with beams of the bare nuclei ${\mathrm{C}}^{+6}$, ${\mathrm{N}}^{+7}$, ${\mathrm{O}}^{+8}$, and ${\mathrm{F}}^{+9}$ at energies of 1.05, 1.50, and 1.88 MeV/amu. The data deviate by as much as a factor of 2.6 from the ${{Z}_{1}}^{2}$ dependence predicted for ionization cross sections. This deviation monotonically increases with ${Z}_{1}$ and increases somewhat with velocity.