Photon counting X-ray imaging with CdTe pixel detectors based on XPAD2 circuit

A semiconductor hybrid pixel detector for photon counting X-ray imaging has been developed and tested under radiation. The sensor is based on recent uniform CdTe single crystal associated with XPAD 2 counting chip via innovative processes of interconnection. The building detector is 1 mm thick, with an area of 1 cm2 and consists of 600 square pixels cells 330 μm side. The readout chip working in electron collection mode is capable of setting homogeneous threshold with only a dispersion of 730 e−. Maximum noise level has been evaluated around 15 keV. First experiments under X-rays demonstrate a very good efficiency of detection. Moreover, imaging system allows excellent linearity over a large-scale achieving count rate of 3×106 photons/s/mm2. Spectrometric measurements point up the system potential in multi-energies applications by locating and resolving X-rays lines of 241Am and 57Co sources.