A High-Speed Data Acquisition System for Segmented Ge-Detectors

When using segmented Ge-detectors for gamma ray tracking it is necessary to determine the segment pulse shapes with high accuracy. A high-speed data acquisition system with many channels, high precision and with high sampling rate is required. To find the optimum performance, we are investigating what can be achieved by a system with extremely high sampling rates, 10 bits @2 GS/s. There are many other applications for such a system. Higher sampling rates usually mean lower bit resolution of the ADC, but with oversampling we expect to achieve a very good energy and time resolution. The system uses high performance FPGAs (Xilinx Virtex-IV) to cope with the data rates delivered by the high speed ADCs and to make all the data processing onboard in real time. Control and monitoring is implemented in an embedded soft processor. This processor is also in charge of the offboard gigabit Ethernet communication. The final system will consist of several separate boards, each with a number of input channels that will have to communicate with each other in real time over a high-speed communication link. The processed result will be transmitted over Ethernet to final storage. The project introduces many challenging issues, which are being addressed in turn with different prototype designs. These issues are: the ADC performance, interfacing the ADCs to the FPGA, implementing the flexible processing algorithms and high speed interconnection between the boards.