数字化核测量系统中参数可调的前端控制器  

Parameters-adjustable front-end controller in digital nuclear measurement system

作　　者：郝德建[1] 张软玉[1] 闫洋洋[1] 王鹏[1] 唐昌建[1] 

机构地区：[1]四川大学物理科学与技术学院,成都610064

出　　处：《核技术》2013年第11期49-54,共6页Nuclear Techniques

基　　金：国家自然科学基金项目(11075111;11055002;10935005)资助

摘　　要：为了构建一套数字化核测量系统,设计并实现了一种适用于阻容反馈式和开关复位式核探测器的前端控制器。导出了辐射计数率n、输入信号幅度Vin、后续ADC变换量程?V及线性放大倍数A之间的数量关系;通过CPLD(Complex Programmable Logic Device)对数字电位器的控制来实现增益的分段调节;通过碲锌镉探测器的不同增益下的测量实验验证了设计的可行性。One digitizer is used to implement a digital nuclear measurement for the acquisition of nuclear information. Purpose： A principle and method of a parameter-adjustable front-end controller is presented for the sake of reducing the quantitative errors while getting the maximum ENOB （effective number of bits） of ADC （analog-to-digital converter） during waveform digitizing, as well as reducing the losing counts. Methods： First of all, the quantitative relationship among the radiation count rate （n）, the amplitude of input signal （Vin）, the conversion scale of ADC （iV） and the amplification factor （A） was derived. Secondly, the hardware and software of the frotu-end controller were designed to fulfill matching the output of different detectors, adjusting the amplification linearly through the control of channel switching, and setting of digital potentiometer by CPLD （Complex Programmable Logic Device）. Results： （1） Through the measurement of 7-ray of Am-241 under our digital nuclear measurement set-up with CZT detector, it was validated that the amplitude of output signal of detectors of RC feedback type could be amplified linearly with adjustable amplification by the front-end controller. （2） Through the measurement of X-ray spectrum of Fe-55 under our digital nuclear measurement set-up with Si-PIN detector, it was validated that the front-end controller was suitable for the switch resetting type detectors, by which high precision measurement under various count rates could be fulfilled. Conclusion： The principle and method of the parameter-adjustable frotu-end controller presented in this paper is correct and feasible.

关 键 词：数字化核测量 核信号 量化误差 CPLD(Complex PROGRAMMABLE LOGIC Device) 

分 类 号：TL82[核科学技术—核技术及应用]