K -shell ionization and characteristic x-ray radiation by high-energy electrons in multifoil targets

Processes of K-shell ionization and accompanying characteristic x-ray radiation (CXR) by high-energy electrons moving through a multifoil copper target are considered. Expressions describing the main characteristics of these processes are derived. It is shown that the average K-shell ionization cross section in the target is not defined just by the target material and the electron energy, but also depends on the number of foils in the target, their thickness and separation between them. The corresponding CXR yield is therefore not unambiguously defined by the aggregated target thickness, but depends on the above parameters as well. It is demonstrated that the average K-shell ionization cross section in a multifoil target can be several times larger than the conventional cross section of this process without the density effect impact. This results in a considerable enhancement of CXR yield from the multifoil target compared to the case of electron incidence upon a single foil of the same aggregated thickness. Comparison of CXR yield in the considered case with the yields of some other types of x-ray emission in multifoil targets is made.