| The birth of Nuclear Physics can be traced back to the works of Becquerel and of Rutherford, who discovered radioactivity (Becquerel, 1896) and proposed a theory where the atom has a massive charged core, the nucleus (Rutherford, 1911). A few years later the Quantum Mechanics was developed (Schr¨odinger, 1926) and the first machine to accelerate nuclei were built (Cockcroft and Walton 1930, Van de Graff 1931). These and other experimental and theoretical findings made it possible to begin a systematic study of the nucleus that is still under way.Our current knowledge of nuclei covers many aspects of nuclear behavior (radioactivity, energy spectra, nuclear reactions, stellar nucleosynthesis,…) and it has found also several practical applications in everyday life. Nevertheless, the difficulty of having a unique theory able to explain completely the behavior of nuclear matter still challenges both theoretical and experimental physicists. From an experimental point of view the goal is to perform high“quality”measurements (high resolution and granularity, low thresholds,…) that can be used to verify and improve the existing theories.For decades the electrical output of a particle detector has been analyzed using (rather sophisticated) analog methods, and using digital electronics only for final data conversion, acquisition and storage.Nuclear spectrum is one of the most important information needed in the research work of high energy physics, nuclear physics, heavy ion physics and nuclear technology application. The improvement and development of nuclear spectrum measurement method is a focus question for discussion all along in nuclear measure domain.In the last few years these technologies have reached such a development status to make them attractive for the nuclear physics field. The electrical output of a particle detector can be digitized and the corresponding data properly processed to extract all the information needed. If successful this approach would allow a major renovation in the organization of large experiments, due to the important electronic simplification and to the greater flexibility of these methods with respect to the standard analog methods. Moreover, because of the wide spread of these technologies in the consumer market, many industrial companies are actively developing various components related to digital information manipulation, thus lowering the general cost of these systems.Based on the nuclear detector system output, a set of digital nuclear spectrum measurement system (DNSMS) includes waveform digitizing system (WDS), digital signal processing (DSP) system and data acquisition system. The research content of DNSMS includes study on the following fields: the WDS, the implement principle and method of the DSP system, the design of hardware circuit of the spectrometer, the implement of digital filter in hardware.In this thesis, based on investigation in high-speed digital technology and research in a variety of digital filtering algorithms, a common nuclear energy spectrometer prototype system based on online digital signal processing has been designed. It can change the coefficients of the digital filter without changing the hardware design.The innovations of this thesis are shown as follows:1. Designed and developed a prototype system for digital nuclear spectrum measurement; use FPGA devices to achieve online digital signal processing such as trigger, filter, peak extraction; provide technical support for the realization of the full-digital spectrometer.2. Simplify the hardware structure, reduce the complexity of analog circuits, make full use of the adaptability and flexibility of digital processing technology, give a different set of filter coefficients for different detector signal, achieve the online regulatory function, and enhance the versatility of the system, so that the same hardware system can be used for the measurement of different spectra. |
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