High Two-Dimensional Arrays Based On Resistive Charge Division Readout

Newly 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 E-X = 60 keV (Am-241), becoming approximate to 9 % at E-X = 122 keV (Co-57). Further, a spatial sensitivity of approximate to 5 mu m and a spatial resolution of approximate to 40 mu m in both the directions parallel to the anode and to the cathode strips have been obtained at an energy equivalent to approximate 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 < E-X < 120 keV.