Design of a 32 channel readout system for x-ray cargo inspection

In recent years, X-ray cargo inspection systems have been rapidly being installed at ports, airports, and borders to strengthen the security of baggage and the prohibition of transaction with drugs and contraband. We at Korea Atomic Energy Research Institute are currently developing a dual-energy X-ray cargo inspection system. In this study, a 64-channel charge sensitive readout system consisting of two 32-channel readout systems has been designed for collecting and amplifying signal charges from detector arrays. The 32-channel readout system was composed of 8 detector arrays (four photodiodes per one detector array, 2 mm pitch), 32 hold switches, 32 charge integrators, 32 reset switches, 32 sample-and-holds, 32 output switches, an output buffer, a frequency divider (divide by 4), and a 32-bit shift register. Each component was well designed and optimized for our system, and the size of the fabricated circuit board is 135 mm×71.5 mm. From the visible light tests, the output pulses and the corresponding images were successfully acquired according to the intensity of the incident light