HgI2 Two-Dimensional Arrays Based on Resistive Charge Division Readout

Abstract

AbstractNewly designed HgI2 two-dimensional arrays based on resistive charge division, obtained by depositing a Ge surface resistive layer between the readout Pd strips, have been fabricated. These detectors, coupled with very low noise preamplifiers, have shown a high detection efficiency over a large active area and an energy resolution of 15% for X-ray energy Ex =60 keV (241Am), becoming ≈ 9% at Ex = 122 keV (57Co). Further, a spatial sensitivity of ≈ 5 μm and a spatial resolution of ≈ 40 μim in both the directions parallel to the anode and to the cathode strips have been obtained at an energy equivalent to ≈ 40 keV, by making use, for a fine spatial characterization of the devices, of a laser beam spot with wavelength tuned to match the crystal bandgap (582 nm). These devices, with optimized cathode layer resistances, could be successfully employed in basic research (for example Bragg X-ray spectrometry) and for imaging in radiological and space applications, at least in the important energy range 40 <Ex <120 keV.