The hard X-ray response of a large area HgI2 detector

We summarise the results of a number of X-ray measurements on a 1.06 cm2, 0.18 cm thick HgI2 detector carried out at the European Synchrotron Research Facility at Grenoble, France. The detector energy response function was found to be linear over the energy range 8–27 keV with an average rms non-linearity of 0.6%, consistent with statistics. At room temperature, under full area illumination, the FWHM energy resolution was 1.4 keV at 5.9 keV rising to 3.9 keV at 59.54 keV. Under pencil beam illumination, the measured energy resolution at 8 keV was 1.4 keV FWHM at a detector temperature of 9°C. Using a 50×50 μm2 10 keV monoenergetic X-ray beam, the spatial uniformity of the detector response was determined by a raster scan technique to be at the ±5% level.