LaAl3(BO3)4的合成及其晶体结构的研究

在研究LnAl3(BO3)(Ln=稀土元素，Y）的合成及发光特性过程中，发现镧铝硼酸盐LaAl3(BO3)4具有一种新的晶体结构。本文用助熔剂法合成了LnAl3(BO3)4(Ln=Gd,La)单晶样品，LaAl3(BO3)4为薄板状，而GdAl3(BO3)4为六方的棒状，用TREOR90程序对LaAl3(BO3)4粉末样品的X射线衍射数据进行了指标化，结果为：LaAl3(BO3)4属正交晶系，晶胞参数为a=0.93586(4)nm,b=0.79904(3)nm,c=0.40626(6)nm,V=0.34595nm^3，在1000℃空气环境下，用硝酸盐热分解法合成了单相LnAl3(BO3)4:E3 （Ln=Gd,La)荧光粉并研究了其发光特性，结果表明：LnAl3(BO3)4:Eu^3 (Ln=Gd,La)是非常有前途的等离子显示器用荧光粉。     

Design and gamma sensitivity measurement of a novel dual-emitter vacuum Compton detector

A novel dual-emitter vacuum Compton detector (D-VCD) with higher gamma ray detecting efficiency is proposed. The emitters are made of Ta--Al clad metal. The gamma ray sensitivity is studied by Monte Carlo simulation using the MCNP code. A comparison between calculations and results measured by using the 1.25~MeV gamma ray of Co-60 is also performed. Experimental sensitivities for two sample D-VCDs with the same materials and structures are 1.92×10^ - 20 and 2.02×10^ - 20~C.cm²/MeV separately, which are consistent with the simulation result of 1.98×10^ - 20~C.cm²/MeV and are 4 times higher than that of VCD with a single Fe emitter. According to the simulation results, in a gamma energy range from 0.5 to 3~MeV, the maximum sensitivity variance for the D-VCD is less than 15%, and less than 5% in a range from 1 to 2~MeV in particular. The novel D-VCD is applicable to the detection of intense pulse gamma rays.     

DT聚变脉冲中子产额的活化测量法

设计了一个测量高强度DT聚变脉冲中子产额的活化探测器.该探测器由中子慢化体、天然银片、塑料闪烁体和光电倍增管组成,其输出电流通过一个小电流计来获取.通过分析探测器在直流标定和脉冲测量两种状态下输出电流的变化曲线,求解出了特征参数,进而推导计算出DT聚变脉冲中子源的产额.实践证明,这种测量方法与传统的活化法相比,减少了对...     

Fluence rate linear response limit of a scintillators to γ-rays

Scintillation detectors based on LSO, CeF and PbWO are the main candidates for measuring γ-rays in a mixed γ/n pulsed radiation field with high intensity. An experiment using the Lissajous figure method to study the high fluence rate response behavior of three kinds of commonly used scintillators is introduced in this paper. The result shows that the fluence rate linear response limit of LSO and CeF is 1.9×10¹⁹ and 2.1×10¹⁸MeV/(cm²·s), respectively, and the PbWO scintillator still maintains linear response when the fluence rate of γ-ray is up to 2.0 × 10²⁰ MeV/(cm²·s).     

溴化镧高剂量率线性响应范围的测定北大核心CSCD

研究了溴化镧晶体在高剂量率照射下的线性响应特性,采用李萨如图形法测量得到溴化镧晶体对γ高剂量脉冲的线性响应上限。实验结果表明:溴化镧晶体在能注量率小于2.0×1018 MeV/(cm2·s)时输出仍为线性,当能注量率高于此值时,晶体的响应出现非线性现象。     

N~+注入修复外延Fe膜面内六重磁对称

为了研究离子注入对外延磁性薄膜面内磁各向异性的影响,用离子加速器对在有错切角的Si(111)面上外延生长的Fe膜进行了N~+注入实验.随着N~+注入剂量的增加,外延生长的Fe膜的面内磁各向异性逐渐从二重对称改变为六重对称.通过透射电子显微镜和刻蚀实验验证,发现离子辐照改变了Fe膜表面和界面的状态.未辐照Fe膜面内二重磁对称来自于由于Si(111)面的错切使得在薄膜界面和表面处形成的原子台阶.N~+注入的溅射作用使得Fe膜表面的原子台阶被擦除,N~+注入使得缓冲层和Fe膜界面处相互扩散导致界面处原子台阶消失.因此,外延Fe膜在大剂量N~+注入后表现出Fe(111)面诱导的六重磁对称.研究结果对于提高面内磁记录密度有潜在的应用价值.