A 20 kpixels CdTe photon-counting imager using XPAD chip

A 20 kpixels CdTe sensor has been hybridized on XPAD3S CMOS photon-counting chips, forming a 19,200 pixels imaging device. P-type CdTe with rectifying contact has been employed. This sensor works in hole collection mode with a pulse shaping time of about 150 ns. Detector construction and operation are described, and first results obtained with 241Am source as well as diffraction images using an X-ray synchrotron beam are presented. Polarization effects are present, but remain at a very manageable level.