闪烁体荧光传输特性对ETOF探测器性能的影响

为了对BESⅢ端盖飞行时间探测器(ETOF)的测试结果给出合理的解释, 采用Monte Carlo模拟软件包Geant4, 对该探测器测量高能带电粒子的性能进行模拟研究. 详细探讨了当粒子击中ETOF模块不同位置时, 其闪烁体荧光传输特性与探测器模块输出信号之间的关联, 以及PMT输出信号甄别阈值的选取对闪烁探测器本征时间分辨的影响, 并寻找可能的改善时间分辨的方法. 为进一步提高ETOF的性能提供参考.     

透同光路指示光的CO_2激光器

报导封离型可透同光路指示光的ＣＯ２激光器的研制，并给出了其电流—工作特性曲线。对需可见光作同光路指示的ＣＯ２激光应用整机的开发，开辟了一条新的途径。     

光栅衍射法测量超短光脉冲的宽度

本文详细阐明了光栅衍射法测量超短光脉冲宽度的原理。测量了ＴＥＡ－Ｎ２激光器泵浦的短腔染料激光器输出的光脉冲的宽度。其结果与用条纹相机测得的结果一致。     

利用液晶光阀实现的光学形态变换

提出了基于液晶光阀的光学二值图像领域处理器，利用它完成了扩、蚀和边缘检测等形态变换操作，并给出了实验结果。     

光场力对烧蚀物时空分布的影响

对烧蚀物的时空分布进行了研究。烧蚀物离开靶材表面时的速率分布由蒸发机制决定,在激光作用时间内烧蚀物的传输行为由扩散机制和光场力机制共同决定,激光作用结束后烧蚀物的传输行为由扩散机制单独决定,并解释了烧蚀物的时空分布及烧蚀物趋光运动的现象。     

Properties of polystyrene-poly(methylmethacrylate) random and diblock copolymers in dilute and semidilute solutions

Solution properties for random and diblock copolymers of polystyrene (PS) and poly(methyl methacrylate) (PMMA) have been measured by dynamic and total intensity light scattering in solvents of differing quality. The results are compared with the corresponding properties for PS and PMMA homopolymers of similar molecular weight, in order to determine if interactions between unlike monomers are significant. The hydrodynamic radius (R_h) and diffusion second virial coefficient (k_d) for the random copolymer are found to be larger than the corresponding values for the homopolymers in a solvent which is near-theta for the two homopolymers, whereas no such effect is observed for the block copolymer. This suggests that most intrachain interactions occur a relatively short distance along the chain backbone. In a mutual good solvent R_h and k_d of the random copolymer are comparable to the average of the values for the homopolymers, indicating that in a good solvent monomer/solvent interactions dominate over monomer/monomer interactions. For an isolated diblock copolymer in a mutual good solvent, there is no evidence that interactions between unlike monomers lead to additional expansion of the entire molecule, as measured by R_h, nor expansion of the individual blocks as probed by light scattering with one block optically masked. However, at low but finite concentration there is evidence (the coefficients of the binary interaction terms in the viscosity and the mutual diffusion coefficient, and the second and third virial coefficients) that a weak ordering effect may exist in block copolymer solutions, far from the conditions where microphase separation occurs. Finally, measurements of ternary polymer-polymer-solvent solutions show no dependence on monomer composition or monomer distribution for the tracer diffusion of probe PS-PMMA copolymers in a PMMA/toluene matrix. This indicate that the frictional interaction is largely unaffected by interactions between unlike monomers. However, there is evidence that the thermodynamic interaction is more unfavorable between a random copolymer and the homopolymer matrix than between a diblock and the matrix. © 1994 John Wiley & Sons, Inc.     

光纤码分多址技术在城域接入网中的应用

分析了光纤码分多址技术O -CDMA在城域接入网中的应用。回顾了O -CDMA技术的发展历史 ,详细地介绍了O -CDMA技术的特点 ,其具有的公平性、灵活性、网络控制管理、对服务区处理能力以及高的安全性使O -CDMA技术成为较好的城域接入网技术。阐述了目前在应用中O -CDMA存在的一些技术方面的问题     

动态光散射实验

动态光散射技术是测量纳米及亚微米颗粒粒径的有效方法．本文介绍了动态光散射实验的原理、实验装置及方法，并测量了粒径为85nm的聚苯乙烯水溶液的粒径，分析了实验产生误差的原因．     

改进型迈克耳孙干涉仪

采用分光梭镜代替迈克耳孙干涉仪中的分束镜和补偿板，不仅消除了杂散光斑，且简化了仪器的结构．