Low energy background in mercuric iodide X-ray spectrometers

The origins of the continuous background (window effect or dead layer) in mercuric iodide X-ray spectrometers are investigated. It is found that photo-electron escape and carrier diffusion are the dominant mechanisms of incomplete charge collection in the energy range of interest (from 3–60 keV). X-ray spectra measurements, computer calculation and photo-response measurements are presented in support of the proposed model. Many observations of detector behavior made in the manufacturing and application of mercuric iodide X-ray detectors can be explained by this model.