As the applications of radioisotope become more and more popular, the demand of contamination monitors for radio surface contamination measurement gains. The 2πα and 2πβ emitter measurement system is the primary standard for contamination monitors calibration. Each country has its own system to achieve quantity transfer and traceability according to measurements which refers to a and β standard plane sources. The 2πα and 2πβ emitter measurement system of our country based on analog devices is maintained in National Institute of Metrology. It needs to be upgraded because of the severe burn-in after years of operation.According to the investigation of other 2πα and 27πβ emitter measurement systems over the world, the research of the system mainly focuses on the improvement of the detectors. No relative research on the digitalization of electronics has been made. Therefore, this article introduced a new thought to digitize the 2πα and 2πβ emitter measurement system. The development provides the basis in theory and technique for 2πα and 2πβ emitter measurement system digitalization.Compared to the analog system, digital system has better flexibility and stability. It becomes possible to distinguish signals from noises through digital processing algorithm. Moreover, the digital system has more benefits in volume, power dissipation and ease of operation, which can save costs of emitter measurement.The 2πα and 2πβ emitter measurement system is maintained with the filter processing and the count processing. Filter processing needs to be real-time and responsive while counting processing needs to be flexible, controllable and eminently accurate. To meet the requirements, this article introduced an architecture which comprises an ADC combined with a FPGA for real-time filter processing, a computer program for count processing and a USB chip for communicating. On this basis, we designed and produced an acquisition board integrated with ADC, FPGA and USB chips and made the selection of the chips according to the demands of the system. The acquisition board could guarantee the performance of the system and achieved with smaller shape and lower power consumption.After the fabrication of the acquisition board, we made the research on the digital filtering and then implemented it in FPGA logic, which includes the algorithm about pole-zero cancellation, pulse shaping, and baseline restoration. The interfaces to the ADC and USB were integrated into the logic to accomplish the communication between the chips. Moreover, we implemented data extraction algorithm in the logic to improve the efficiency of the transmission and to save the space of the memory.Meanwhile, we designed the digital processing program for the system, which has graphical user interface for operation convenience. The program was developed based on windows platform with the design language C sharp. This makes program available on most of computers. The program controls the measurement and computes the counting rate of the particle. The emitting rate of the particle can be resolved from the counting rate after the correction of dead time, background and extrapolation.After the system was developed, we made test on the electronics to obtain the correction factor of the acquisition. Finally, we made measurement on the samples of radioactive sources using the new designed digital system. Comparisons were made with the analog based 2πα and 2πβ emitter measurement system. Result showed that the new designed digital system are in agreement with the analog system within the uncertainty of the measurement. |