【作者】 王新华；

【导师】 王铁山；

【作者基本信息】 兰州大学 ， 核科学与技术粒子物理与原子核物理， 2008， 硕士

【摘要】 在核工程的理论设计中,需要测量介质内低能区的中子积分实验数据;在反应堆的概念设计中,结构材料及组合装置内低能区的实验数据显得尤为重要;在核数据的编评中,目前已有的实验数据主要集中在高能段,而高精度的低能段中子实验积分数据目前非常缺乏。因此开展介质内低能段中子能谱测量技术的研究是非常必要的。本论文研究包括以下几个方面:1、考虑在介质内部测量100 keV—2 MeV的中子能谱,充分分析比较了当前各种典型的中子探测谱仪的优劣,最终选择含氢正比计数管作为介质内中子能谱测量的探测器。2、分析以前的资料和数据,结合将要开展实验的实际情况制作了一个球形含氢正比计数管样管;利用球形含氢正比计数管样管内壁的²³⁵U涂层发射的α粒子对计数管的坪曲线、倍增因子和能量分辨进行了测量,确定了工作电压。3、计算了影响计数管响应函数的两个主要因素:壁效应和非均匀性电场,将计算结果输入到含氢正比计数管单能中子响应函数MC程序,利用该程序对不同能量的单能中子在计数管内的响应函数进行了计算。4、利用高压倍加器中子发生器产生的D-D和D-T中子以及静电加速器中子源产生的50 keV—1400 keV的低能中子对计数管单能中子能量响应及计数管的中子各向异性进行了研究,并对计算的响应函数进行标定。利用计数管内壁的²³⁵U镀层发射的α粒子和加速器产生的准单能中子,对测量系统进行了能量刻度。5、研究了含氢正比计数管测量得到的反冲质子谱的解谱方法。用逆矩阵结合最小二乘法编写了解谱程序,利用该程序对测量到的反冲质子谱进行了解谱。分析了几个解得的准单能中子谱,分析结果表明研制的球形含氢正比计数管可以用于介质内2 MeV以下中子能谱测量。更多还原

【Abstract】 Integral experimental data in low-energy neutron inner medium are essential to theoretical design in nuclear engineering. Experimental data in low energy neutron are very important to structure materials and assemblies for principle design of fission and fusion reactor. At present, evaluated nuclear data are mostly composed of high energy neutron data. High precision data for low energy neutron are scarce. So, some measurement techniques have been developed to measure 100 keV-2 MeV neutron in medium in this paper.Five aspects of the measurement technique for 100 keV-2 MeV neutron in medium were investigated as listed below:1. Taken into account neutron field to be measured in medium and low energy of the neutron, performance of some neutron spectrometry were comprehensively compared and analyzed, spherical proton recoil proportional counter has been candidate as the detector to acquire neutron spectra.2. Based on the further experiment, a spherical proton recoil proportional counter was developed by analyzing distributed data and papers. Energy resolution and volt performance of counter were tested, by using alpha particle emitted by ²³⁵U coated at inner wall of spherical proton recoil proportional counter as calibration.3. Wall effects and non-uniformity electric filed effects were calculated with Srim2003 and ANSYS10.0, respectively. The acquired data were inputted the MC code, which was used to simulate response function of counter for mono-energy neutron.4. Several kinds of low mono-energetic neutrons induced by NS-200 neutron generator and 2.5 MeV proton accelerator were used to verify response function and anisotropy of spherical proton recoil proportional counter. Energy linearity of spectrometry was calibrated by Alpha particle from ²³⁵U and mono-neutron from neutron generator.5 Method of unfolding of pulse height spectra acquired was studied by spherical proton recoil proportional counter. The method of unfolding is based on the Least-squares and reverse-matrix method. The unfolded neutron spectra indicated that the spherical proton recoil proportional counter is capable of neutron measurement of （100 keV-2 MeV） neutron in medium.更多还原