Study of the Production ofKX Rays in Ca, Ti, and Ni by 2-28-MeV Protons

Using a proportional counter as an x-ray detector, thin-target yields, as well as $K$ x-ray production and ionization cross sections, were determined for Ca, Ti, and Ni when bombarded with 2-28-MeV protons. Broad maxima in the cross sections were found at approximately 8.5, 10.4, and 16.6 MeV for Ca, Ti, and Ni, respectively, in agreement with theoretical calculations based on the Bethe-Born approximation. The shape of the cross-section-versus-bombarding-energy curve agrees well with theory. However, the absolute values of the cross sections were observed to be higher than predicted by theory when the generally accepted value for the effective charge ($Z-0.3\mathrm{}$) was chosen.