Spectral performance of a pixellated X-ray imaging detector with suppressed charge sharing

The ability to perform X-ray imaging with energy resolution on a small pixel detector is severely limited by the charge sharing in the detector. Different schemes have been proposed in order to overcome the problem. Previous studies using synchrotron radiation have shown that, for a 300-μm-thick Si detector with 55 μm pixel size, almost no charge sharing occurs for photons hitting the centre of each pixel. In this study, we have used slits to focus the beam from a standard X-ray unit onto the centre of a pixel for a MEDIPIX detector. The attenuation of the spectrum was measured for a number of samples of different materials with K-edge energy in the range of 30–50 keV. The measurements were performed by scanning an energy window through the spectrum. Requirements for new X-ray imaging systems with true energy resolution, based on these measurements, are discussed.