【作者】 王喜宗；

【导师】 周剑良； 颜拥军；

【作者基本信息】 南华大学 ， 辐射防护及环境保护， 2010， 硕士

【摘要】 镭同位素[1]示踪在海洋学研究中具有广泛的应用,例如,研究近岸和河口海区1—10天的海洋学过程等。利用逻辑电路延迟符合测量氡同位素[2]是间接分辨镭同位素的重要手段,目前该方法已成为海洋学研究的重要方法之一。本文研究了以软件仿真方式产生氡及其同位素的仿核脉冲数据,探索用软件方法实现延迟符合法分辨氡同位素;该方法可以灵活方便改变延迟时间和开门时间寻找具有较好的分辨效果,仿真了不同粒子总数及不同AR活度比情况下的延迟符合测氡的参数设置。发现开门时间为氡同位素子体半衰期的3-5倍较为合适,并与国外文献试验中测量结果的进行了比对,结果显示,该方法可降低测量成本,延迟时间调整方便,对低水平活度氡同位素测量具有借鉴作用。同时对数字符合进行了初步的研究,仿真[3]研究了模数转换器的采样速率和采样位数对双指数核脉冲信号的影响,并采用四种带通滤波器算法对数字化双指数[4]核脉冲信号进行了滤波成形研究,通过研究发现,椭圆滤波器[6]对高频噪声的滤波效果较好。更多还原

【Abstract】 Radium isotopes study have an wide application in the field of oceanography, for example, study on the oceanography process of estuarine area and nearshore within 1-10 days etc. we can indirectly measure radium isotopes by logic delayed circuit which can directly measure and discriminate radon isotopes, and this method is an important means of measure radium isotopes in oceanography. In this paper we seek to generate pseudo nuclear pulse data of radon and radon isotopes by the way of software. and using MATLAB software simulate the delay coincidence to study“Ra.De.CC”, This method can conveniently change the delay time and the gate time for finding a better effect . simulation the delay and gate parameters with different particles numbers and AR activity ratio. Finding that, the appropriate gate time is 3-5 times of the half-life of radon daughters, and checking with foreign measuring results in literature, the result shows that this method can reduce the cost of measurement, easily change, is a reference for measuring low level radon isotope.At the same time ,we have a study on the digital delay coincidence, for example the ADC sampling rate and sampling bit for the double exponential nuclear pulse signal. simulate four types bandpass filter, and through the research we found that the effect of elliptic filter for high-frequency noise is better for digital double exponential nuclear pulse signal.更多还原