K- and L-shell ionization by energetic lithium beams

Abstract

We have measured target K x-ray production cross sections for lithium projectiles incident on thin aluminum, scandium, copper, and tin targets at energies from 4 to 34 MeV. The Sn L x-ray cross sections for those energies have also been obtained. In addition, similar measurements for protons incident at velocities matching those of the lithium projectiles have been made. The absolute magnitudes of the lithium ionization cross sections as deduced from the above results are well predicted by the binary-encounter approximation. Substantial deviations downward occur in the Sc and Cu cases for projectile velocities below one-half of the L-shell electron orbital velocities. These decreases in the cross sections, which are also evident in the data when scaled by the corresponding proton values, are examined in light of a previous treatment of increased binding effects.