【作者】 徐静；

【导师】 王南萍；

【作者基本信息】 中国地质大学（北京） ， 通信与信息系统， 2009， 硕士

【摘要】 便携式γ能谱仪是放射性污染检测的主要工具之一。随着核科技的发展以及对核技术认识的不断深入,γ能谱仪向着高性能、高集成化、高智能化方向快速发展,方便、快捷的便携式γ能谱仪越来越多地成为人们的需求。国外的便携式多道γ能谱仪产品性能较高、功能较齐全,但价格也相对较昂贵,目前在国内大多数用户中还难以得到广泛应用。在国内,人们在尝试将嵌入式系统引入到放射性仪器的研制中。论文设计了基于嵌入式Linux的多道γ能谱仪系统,该系统由带有高压电源的NaI(T1)探测器、主放电路板和嵌入式开发板构成。主放电路板除包括传统的峰值保持电路和噪声甄别电路外,还增加了一些新的功能:正负极性选择开关、不同放大倍数可调电路、过压保护电路以及电源滤波电路。主要从嵌入式处理器、嵌入式操作系统和嵌入式存储器等三个方面,选择了一款性价比合适的嵌入式开发板。按照嵌入式的开发流程,完成了交叉编译环境的搭建、系统引导程序BootLoader的烧写以及Linux内核的移植。在综合分析多道γ能谱仪系统通信机制的基础上,设计完成了该系统进行数据采集和存储的核心代码。通过对系统的整体测试,得到的结论是:正负极性选择开关增加了对不同探测器的适应性;通过软件可以控制输入信号幅值在不同放大倍数之间灵活改变;在信号幅值过大时过压保护电路能够防止嵌入式开发板不受损坏;电源滤波电路减小了电源的变化对γ能谱仪测量过程造成的影响。主放电路板和嵌入式系统能够顺利实现通信,整个多道γ能谱仪系统能采集到闪烁探测器的输入信号并存储显示。论文的研究,实现了基于嵌入式系统的多道γ能谱仪的雏形。由于其具备功耗低、体积小、成本低以及集成度高等优点,可广泛应用于野外现场测量,对地质学研究、寻找矿产资源以及解决水文地质和工程地质等工程技术难题具有重要意义。更多还原

【Abstract】 Portable gamma-ray spectrometer is one of the most important tools for determining radioactive contamination. With the development of technology and the knowledge of nuclear technique, gamma-ray spectrometer develops towards the direction of high-performance, high integration and high-intelligent, thus a convenient, fast and portable gamma-ray becomes more and more people’s needs. The portable multi-channel gamma-ray spectrometer aboard mostly has higher performance and more fully features, but the price is relatively more expensive, so at present, it is difficult to be widely used for most domestic users. In China, people are trying to introduce embedded systems into the development of radiological equipment.In this paper, a multi-channel gamma-ray spectrometer based on embedded Linux system was designed. The gamma-ray system consists of the NaI (Tl) detector with high voltage power, the main amplify circuit and embedded board. Besides the traditional peak-hold circuit and noise discriminator unit, there are also some new features in the main amplify board: a cathode and anode switch,a magnification-chosen circuit,over-voltage protection and power filter. Considering from embedded microprocessor unit, embedded operating system and embedded memory, an appropriate cost-effective embedded board was chosen. In accordance with the embedded development process, the cross-compiler environment was built, Boot Loader was written, and Linux kernel was transplanted. Based on a comprehensive analysis on the communication of the multi-channel gamma-ray spectrometer system, the core code about data acquisition and data storage has been finished.Through the overall test of the gamma-ray spectrometer system, the conclusion is that: the cathode and anode switch increases the adaptability of different detectors; different magnification can be controlled flexibly by software; the over-voltage protection circuit can protect the embedded when the signal amplitude is too large; the power filter reduces the impact on the gamma-ray spectrometer when power change. The main amplify circuit board and embedded system can communicate easily, and the whole multi-channel gamma-ray spectrometer can get the input signals of detector and store them for display.This research finished the prototype of muli-channel gamma-ray spectrometer based on embedded system. Because of its low power comsumption, small size, low cost and high integration, it can be widely used in field measurements and also it has great significance in geological research, searching for mineral resources, and finding solution to engineering and technology such as hydro-geological and engineering geology.更多还原