Measurement of angular distributions of K x-ray intensity of Ti and Cu thick targets following impact of 10-25Â keV electrons

We present new results on angular distributions of the relative intensity of Kα and Kβ x-ray lines of thick targets of Ti (Z = 22) and Cu (Z = 29) pure elements following impact of 10-25 keV electrons. The angular measurements of the K x-radiations were accomplished by rotating the target surface with respect to the electron beam direction. The x-rays emerging from the target surface in reflection mode were detected by an energy dispersive Si P-I-N photodiode detector. The resulting variation of the relative intensity of the characteristic lines as a function of angle of detection and impact energy has been found to be anisotropic and it is considered to arise due to change in path lengths at a given incidence angle α for the photons generated by direct as well as by indirect K shell ionization processes. The measured angular variations of relative intensity of Kα and Kβ x-ray lines of both targets are found to increase by about 60-70% in going from θ = 1050 to 1650 at a given impact energy; however there is a slight indication of impact energy dependence of Cu Kα x-ray line as also noted by the earlier workers. We compare the experimental results with those obtained by Monte Carlo simulations using PENELOPE calculations; the agreement between experiment and theory is found to be satisfactory within uncertainties involved in the measurements and the theoretical results.