FPGA based data acquisition and processing for gamma ray tomography

Data acquisition and processing for gamma ray tomography has traditionally been performed with analogue electronic circuitry. Detectors convert the received photons into electrical signals which are then shaped and conditioned for the next counting stage. An approach of using a FPGA (Field programmable gate array) based data acquisition and processing system for gamma ray tomography is presented in this paper. With recently introduced low cost high speed analogue to digital converters and digital signal processors the electrical output of the detectors can be converted into the digital domain with only simple analogue signal conditioning. This step can significantly reduce the amount of components and the size of the instrument as much of the analogue processing circuitry is eliminated. To count the number of incident photons from the converted electrical signal, a peak detection algorithm can be developed for the DSP (Digital Signal Processor). However due to the relatively high sample rate the consequently low number of available of processor cycles to process the sample makes it more effective to implement a peak detection algorithm on the FPGA. This paper presents the development of the acquisition system hardware and simulation results of the peak detection With previously recorded experimental data on a flow loop.