ProjectilezDependence ofKX-Ray Emission Induced by Alpha Particles and Deutrons

Measurements of the yields of $K$ x rays from Cl, Ca, Ti, Ni, and Cu targets and $L$ x rays from Sn and Au targets produced by bombardment with $\alpha$ particles and deuterons of identical velocities have been performed at energies from 2.9 to 20 MeV/amu. The ratios of $K$ x-ray yields for the Cl, Ca, Ti, Ni, and Cu targets all show substantial deviations from the ratios expected on the basis of the theoretically predicted $z^2$ dependence of the Born-approximation and binary-encounter descriptions. The deviations exhibit a "crossover" behavior in which the measured ratios are smaller than expected at low projectile velocities, rise above the expected value at higher velocities, and finally decrease toward the expected value at the highest velocities. The relationship between these deviations and similar deviations in stopping-power measurements has been investigated. Angular distributions of Ti $K$ x rays and Sn $K$ and $L$ x rays were also measured and found to be isotropic to an accuracy of about 2%.