锗酸铋晶体中子辐照诱导色心的研究

对锗酸铋晶体进行了两种不同剂量的14.6MeV快中子辐照.利用常规的核探测技术,通过测量其辐照前后　Cs的γ能谱来观察峰总比的变化,研究了辐照诱导色心对于荧光输出和中子剂量对于辐照诱导色本底能谱和137心密度的影响.     

BGO闪烁晶体的辐照损伤及恢复研究进展

介绍了BGO(Bi4Ge3O12)闪烁晶体的发光原理,简述了国内外某些针对BGO闪烁晶体的辐照实验.分析了晶体受到辐照前后透射率、相对光输出及吸收系数的变化.分析表明:BGO闪烁晶体辐照损伤的主要因素是形成俘获色心,通过退火及光子照射可以使闪烁晶体的性能得到一定的恢复.简要介绍了提高BGO闪烁晶体耐辐照性能的方法,并指出通过掺杂及改变晶体生长方法是提高晶体耐辐照性能最重要的方法.     

电子束和快中子对BGO晶体辐照损伤的研究

本文采用加速电子束及１４ＭｅＶ快中子轰击ＢＧＯ晶体，通过测辐照前后的γ能谱来研究ＢＧＯ晶体辐照损伤，通常辐照损可随时间恢复，但大剂量快中子产生的损无法修复，由于ＢＧＯ晶体常用射线探测器，电子束和快中子是常用的射线源，所以本实验的结果具有一定的参考价值。     

脉冲中子法检测煤的全水分

给出了利用脉冲中子发生器产生的快中子的非弹性散射[n,n′γ]反应和热中子的俘获[n,γ]反应,对煤的全水分进行分析的原理和方法.采用BGO(锗酸铋)探头作为γ射线探测器,通过多元回归分析方法,较好地解决了元素间的干扰问题.用脉冲中子法测得的全水分分析值与化验值的偏差不超过0.5%.     

世界最长锗酸铋大单晶问世

[科学时报]中国科学院上海硅酸盐研究所中试生产一线近日成功制备出长度达600毫米的锗酸铋(BGO)大单晶。这是迄今为止国际上公开报道的最长BGO单晶(俄罗斯无机化学所曾报道的最长BGO单晶为400毫米)。600毫米BGO大单晶是上海硅酸盐所在中国科学院空间科技先导项目     

5~10 MeV能区γ本底对锦屏深地核天体物理反应测量的影响探究

天体物理感兴趣能区(伽莫夫窗口)的带电粒子核反应截面极小,在地面进行测量会受到宇宙射线诱发本底的严重干扰．进行地下实验室核反应测量成为解决这一问题的主要途径．锦屏深地核天体物理实验（JUNA）装置是我国首个地下核天体反应测量设施,为开展恒星核合成关键反应直接测量提供了绝佳机遇．本工作测量了锗酸铋(BGO)探测阵列和溴化镧(LaBr₃)探测器在JUNA装置上的γ本底能谱,并通过减小符合时间、点火数选择、粒子甄别等技术,进一步压低了5~10 MeV能区的γ本底,同时讨论了探测器本底对部分JUNA计划开展的核天体反应测量的影响．      

“中国牌晶体”团队标准，高分入选首批“上海标准”

正最近,首批"上海标准"发布,上海硅酸盐研究所制定的《正电子发射断层扫描仪用锗酸铋闪烁晶体》团体标准,以终评最高分成功入选。上海硅酸盐研究所成为市科技系统唯一获此荣誉的科研院所。该标准目前已通过国家标准审核,即将发布。推行"上海标准"标识制度是《上海市标准化条例》的创设性规定,由上海市市场监管局指导第三方机构制定。作为我国闪烁晶体学科的创建单位,     

双极晶体管中子辐照后的高温退火特性

利用硅双极晶体管在线监测中子注量,其直流增益和损伤常数是作为探测器指标的重要参数。高温退火可使受到中子辐照的双极晶体管性能部分恢复,进而可以重复使用。开展高温退火特性研究,分析双极晶体管直流增益的恢复程度以及损伤常数的重复性。在快中子脉冲堆上对贴片型3DG121C双极晶体管进行三轮中子辐照,每轮辐照累计注量2.64×10~(13)cm~(-2)。经过第一轮中子辐照后,双极晶体管直流增益下降至辐照前的40%,经过180℃连续24 h的高温退火后,直流增益恢复至辐照前的67%;经过第二轮辐照后,直流增益下降至第二轮辐照前的50%,在相同条件下退火后,直流增益恢复至第二轮辐照前的73%;经过第三轮辐照后,直流增益下降至第三轮辐照前的58%,在相同条件下退火后,其直流增益恢复至第三轮辐照前的87%。三轮实验结果表明:双极晶体管直流增益倒数随辐照中子注量变化的线性关系基本一致,具体表现为其损伤常数具有很好的重复性。利用该高温退火特性,将双极晶体管作为中子注量探测器应用于快中子脉冲堆中子注量在线监测,监测结果与活化箔结果基本吻合。     

利用电子顺磁共振对振Mn刚玉晶体中子辐照变价的研究

测量并对比了掺Ｍｎ刚玉晶体在中子辐照及退火处理前后的电子顺磁共振（ＥＰＲ）谱。结合紫外－可见光吸收谱的结果，发现Ｍｎ＾２＋，和Ｍｎ＾４＋的浓度降低，而Ｍｎ＾３＋浓度增加，虽然Ｍｎ离子的掺杂浓度并无改变，但其价态由于中子辐照而引起了改变，实验结果还表明，中子辐照可晶体内形成Ｍｎ＾２＋与Ｆ＾－心的复合体，但退火后则有一部分转化为Ｍｎ＾２＋与Ｆ心的复合体。     

利用电子顺磁共振对掺Mn刚玉晶体中子辐照变价的研究

测量并对比了掺Ｍｎ刚玉晶体在中子辐照及退火处理前后的电子顺磁共振（ＥＰＲ）谱，结合紫外－可见光吸收谱的结果，发现Ｍｎ２＋和Ｍｎ４＋的浓度降低，而Ｍｎ３＋浓度增加，虽然Ｍｎ离子的掺杂浓度并无改变，但其价态由于中子辐照而引起了改变．实验结果还表明，中子辐照可在晶体内形成Ｍｎ２＋与Ｆ－心的复合体，但退火后则有一部分转化为Ｍｎ２＋与Ｆ心的复合体．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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