Determination of Linear Attenuation Coefficients of Materials by Using Timing Method

Abstract

In this work, gamma-ray linear attenuation coefficients of aluminum (Al) and lead (Pb) materials were determined by using timing method. The used setup is different from the conventional ones. The goal of the presented setup is the fact that it is used the timing technique. The detection system is composed of a 3″ × 3″ NaI(Tl) inorganic scintillation detector and related equipment together with ¹³⁷Cs and ⁶⁰Co radioactive sources. Obtained results are in good agreement with each other.     

PPC和PFS联用去除水源水中Tl和Sb复合污染

为了去除地表水源水加标模拟的重金属铊(Tl)和锑(Sb)复合污染,采用了高锰酸盐复合药剂(PPC)和聚合硫酸铁(PFS)联用强化常规工艺;通过静态烧杯实验和微型移动式平台优化工艺参数,对去除铊和锑复合污染的影响因素(PPC投量、PFS投量和pH)进行分析.实验结果表明,组合工艺可保证水源水在Tl超标2～3倍(0.21 ～0.35 μg·L-1),Sb超标3～4倍(15 ～20 μμg·L-1)的场合出水达标,对应的工艺参数是:pH控制在5.7 ～6.3,PPC投量控制在3mg·L-1以上,聚铁投量控制在40 mg·L-1以上.PPC和PFS联用强化常规工艺可有效去除地表水源水加标模拟的铊(Tl)和锑(Sb)复合污染,并且PPC投量是影响Tl去除的主要因素,PFS投量和pH是影响Sb去除的主要因素.     

行李放射性检测装置的研制

行李放射性检测装置可与现有X射线安全检测装置联合用于放射性安全检测。该装置采用NaI(Tl)探测器，用移动平均法进行放射性检测。在本底为0.1μGy/h、行李移动速度小于0.2m/s条件下，该装置对 ¹³⁷Cs、⁶⁰Co、¹³³Ba核素的可探测活度下限分别为6.7×10³、3.7×10³、6.7×10³Bq，对富集度为90%的U样品，探测质量下限为2g。     

建筑材料放射性核素测量

详细叙述了采用NaI低本底多道γ谱仪测量建筑材料天然放射性核素镭、钍、钾放射性比活度的原理与方法。通过测量纯镭、纯钍、纯钾标准源，计算了谱仪对镭、钍、钾的响应系数。采用逐道最小二乘法分析建材样品中镭、钍、钾放射性比活度，运用以上方法对建材样品标准源进行测量，分析结果与标准数据之差在3％之内，远低于国标对测量不确定度的要求。     

大体积阱式NaI(Tl)探测器的效率计算与测量

使用蒙特卡罗方法模拟计算了一个用于4πγ计数的大体积阱式NaI(Tl)探测器的效率和能谱。采用一系列单能γ源标定探测器,对计算结果进行检验,其结果基本一致,两者间的最大偏差不超过±8%,证明计算结果是可靠的。     

用NaI(Tl)探测器测量γ辐射场剂量特性的加权积分法研究

辐射场剂量特性的测量可以通过剂量率仪或谱 剂量转换的方法来实现。其中一种谱 剂量转换的方法是通过一个G(E)函数 ,把测得的结果直接换算成剂量而不需解谱。本文采用这种方法 ,对一个75mm× 75mm的NaI(Tl)探测器的能谱特性进行测量与分析 ,算出了该晶体的G(E)函数值及估计的误差 ,并用此方法与高气压电离室作了比对测量     

‘Beautiful’ unconventional synthesis and processing technologies of superconductors and some other materials

Abstract

Superconducting materials have contributed significantly to the development of modern materials science and engineering. Specific technological solutions for their synthesis and processing helped in understanding the principles and approaches to the design, fabrication and application of many other materials. In this review, we explore the bidirectional relationship between the general and particular synthesis concepts. The analysis is mostly based on our studies where some unconventional technologies were applied to different superconductors and some other materials. These technologies include spray-frozen freeze-drying, fast pyrolysis, field-assisted sintering (or spark plasma sintering), nanoblasting, processing in high magnetic fields, methods of control of supersaturation and migration during film growth, and mechanical treatments of composite wires. The analysis provides future research directions and some key elements to define the concept of ‘beautiful’ technology in materials science. It also reconfirms the key position and importance of superconductors in the development of new materials and unconventional synthesis approaches.     

电感耦合等离子体质谱法测定铅锌矿中镓铟锗铊

稀散元素是铅锌矿石中重要的伴生元素,为了综合利用铅锌矿资源,在地质、选矿上经常要考查稀散元素镓、锗、铟、铊的含量。研究了利用电感耦合等离子体质谱法测定铅锌矿中镓、铟、锗、铊4种稀散元素,选取了最佳仪器分析条件,通过在线加入内标校正基体效应和接口效应,检出限分别为0.02μg·g-1、0.01μg·g-1、0.03μg·g-1和0.05μg·g-1,相对标准偏差(RSD)为0.85%~2.84%,回收率在93.3%~102.3%之间,明显优于其他分析方法。该方法样品前处理简便、快捷,测定结果准确,令人满意。     

NaI(Tl)闪烁探测器对铯源响应的蒙特卡罗模拟

对NaI(Tl)探测器的γ能谱进行了MC模拟,模拟研究了不同源-探距、不同能量分辨率、不同模拟时间和平面源分布等条件下的137Cs γ能谱.137Cs点源的模拟谱与实测谱的对比表明两者基本相符.