Improved model for the intensity of low‐energy tailing in Si(Li) x‐ray spectra

Accurate tail‐to‐peak intensity ratios are extracted from the spectra produced in a Si(Li) detector by x‐rays of energies 2–10 keV. The widely used model of a surface layer of incomplete charge collection fails to explain the energy dependence of these data. The model is augmented to include loss of photoelectrons travelling back into the ICC layer from an interaction in the active silicon region; this gives excellent agreement with experiment. It is shown that the detection efficiency in the region of low x‐ray energy may be deduced from the tail‐to‐peak ratios, together with measurement of the thicknesses of the beryllium window and the metal contact; a potential source of error in measuring the latter by the popular fluorescence technique is demonstrated.