A digital X-ray imaging system based on silicon strip detectors working in edge-on configuration

We present the energy resolution and imaging performance of a digital X-ray imaging system based on a 512-strip silicon strip detector (SSD) working in the edge-on configuration. The SSDs tested in the system are 300 μm thick with 1 or 2-cm-long strips and 100 μm pitch. To ensure a very small dead area of the SSD working in edge-on configuration, the detector is cut perpendicular to the strips at a distance of only 20 μm from the end of the strips. The 512-strip silicon detector is read out by eight 64-channel integrated circuits called DEDIX [Grybos et al., IEEE Trans. Nucl. Sci. NS-54 (2007) 1207]. The DEDIX IC operates in a single photon counting mode with two independent amplitude discriminators per channel. The readout electronic channel connected to a detector with effective input capacitance of about 2 pF has an average equivalent noise charge (ENC) of about 163 el. rms and is able to count 1 Mcps of average rate of input pulses. The system consisting of 512 channels has an excellent channel-to-channel uniformity-the effective threshold spread calculated to the charge-sensitive amplifier inputs is 12 el. rms (at one sigma level). With this system a few test images of a phantom have been taken in the 10-30 keV energy range.