Dynamic Screening of Projectile Charges in Solids Measured by Target X-Ray Emission

We report a strong dependence of the Al K x-ray cross section in solid Al targets, for thicknesses ranging from 0.5 to 25 {μ}g/cm², on the charge state of the incident oxygen projectiles, in the energy range 12-68 MeV. The results are analyzed in terms of the dynamic screening of the projectile charge by the electrons in the dense target, yielding a dynamic screening rate λ=5.5×10¹⁴ sec^-1 which is consistent with this approach.