Study On Real Time Digital Nuclear Signal Acquisition Based On High Speed ADC

Nuclear signal collection is the key for acquiring nuclear information in the fields of the nuclear safety, nuclear fuel monitoring, nuclear physics, high energy physics, heavy ion physics, etc. Comparing to the analog nuclear signal processing, digital nuclear signal processing is a technique, which first takes use of analog to digital converter(ADC) to capture signal from nuclear detector,then do digital signal process. High-speed acquisition and digital pulse shaping are becoming the trend of nuclear instrument, with the characteristics of stability and flexibility. The analog nuclear instrument is being taken by digital nuclear instrument.The high-speed acquisition for nuclear signal can obtain the information from the signals with microsecond pulse width. It is the first step of digital pulse shaping. Because that Detail sampling data for nuclear signal is the key of pile-up recovery, high resolution energy spectrum and digital pulse shaping. So the high-speed acquisition for nuclear signal is vital for improving the ability of digital nuclear instrument.As the importance of high-speed acquisition for digital nuclear signal processing, the paper has designed a nuclear signal acquisition platform based on FPGA by using nuclear signal adjustable amplifying circuit and high-speed sampling circuit. Finally with the acquisition platform, high-speed acquisition and digital pulse shaping are implemented.The design is to accomplish nuclear signal’s 100 MSPS sampling and real time processing. A high-speed ADC with 105 MSPS is chosen in the project. The project introduces the design of 100 MSPS high-speed acquisition in real-time for nuclear signal. General microcontroller cannot meet the requirement of the transmission for such high-speed signal. Therefore, an FPGA with parallel processing ability is used to realize signal transmission and a FIR filter is also injected in the FPGA. In order to simplify the process of port developing and increase the scalability of data acquisition, an ARM microcontroller is applied as the controller. The communication between the FPGA and ARM is established by SPI, while the communication between the ARM and the software on the computer is formed by USB.Finally, a 137 Cs source is used to test the design. The signal is detected by a Φ75*75 Na I(Tl)scintillator detector. The result shows that the design of hardware was reasonable, and the studying technical route was right, the design can do FIR filter for digital nuclear signal. The design has the functions of high-speed sampling and data storing,it makes high speed sampling come true.