Development of high-speed X-ray imaging system for SOI pixel detector

Abstract: We are now developing new X-ray imaging system by using Silicon-On-Insulator (SOI) Pixel Detectors. The SOI detector is a monolithic radiation imaging detector based on a 0.2um FD-SOI CMOS process. Special additional process steps are also developed to create fully depleted sensing region of 50~500um thick. SOI detector has up to mega pixels, so development of high speed Data Acquisition (DAQ) system is very important in conducting experiments. We have developed readout board named SEABAS2 (Soi EvAluation BoArd with Sitcp 2) for SOI detector. The SEABAS2 board has 16 channels of 65 MSPS ADCs, 4ch DAC, FPGAs and Gigabit Ethernet I/F. To achieve high throughput of the DAQ, we aggressively adopt parallel processing (data taking and storing) and implement FIFO buffers in software. DAQ throughput in previous DAQ system was 6 Hz (41 Mbps) for INTPIX4 detector which has 423 kpixels of 17 um square. With newly developed system, we could improve this rate to 90 Hz (613 Mbps). To take X-ray images for practical purpose such as 3D CT, user have to control the peripheral devices (moving stage, beam shutter, monitoring devices etc.) while taking images. To ease such data taking, we also implemented automatic control function of peripheral devices. Introduction of SOI detectors, the detail of the DAQ system and experimental results are presented.