Effect of local atomic disorder on the half-metallicity of full-Heusler Co2FeSi alloy: a first-principles study

This paper investigates the effect of atomic disorder on the electronic structure, magnetism, and half-metallicity of full-Heusler Co2FeSi alloy by using the full-potential linearized augmented plane wave method within the generalized gradient approximation (GGA) and GGA+U schemes. It considers three types of atomic disorders in Co2FeSi alloy: the Co-Fe, Co-Si, and Fe-Si disorders. Total energy calculations show that of the three types of disorders, the Fe-Si disorder is more likely to occur. It finds that for the Co-Si disorder, additional states appear in the minority band-gap at the EF and the half-metallcity is substantially destroyed, regardless of the disorder level. On the other hand, the Co-Fe and Fe-Si disorders have little effect on the half-metallicity at a low disorder level. When increasing the disorder levels, the half-metallcity is destroyed at about 9 % of the Co-Fe disorder level, while that stays at 25 % of the Fe-Si disorder level.     

加速器控制系统及其进展

目前加速器控制系统普遍采用了分布式体系结构, 使用系统集成工具进行开发, 当前加速器界主流的系统集成工具有EPICS、TANGO和商业SCADA产品. 在硬件方面, FPGA、DSP芯片广泛地用于硬件模块中实现数字化控制, 嵌入式EPICS IOC智能控制器是当今研究的一个热点. 软件方面, 除系统集成工具之外, 各大实验室都建立了自己的软件开发环境, 对软件开发进行标准化管理, 其中开放的软件平台Eclips, Abeans活跃在控制系统软件开发中. 目前具有挑战性的课题是系统高可用性研究. 本文将介绍加速器控制系统及技术方面的现状和进展.     

96MeV 16O+64Ni反应机制的研究

在96MeV ¹⁶O离子轰击下,测量了¹⁶O+⁶⁴Ni反应出射碎片(α直至O元素)的Wilczynski图和角分布,并提出DIC截面和反应时间等物理量;讨论了反应的DIC特征;看到了出射碎片α和Li主要来源于复合核蒸发的迹象.     

80.6MeV 16O轰击27Al反应的弛豫过程的研究

从80.6MeV ¹⁶O+²⁷Al出射类弹碎片的测量实验结果导出了角分布衰减系数、电荷分布及电荷分布的一次矩和二次矩随TKEL的变化. 对该反应中的弛豫过程进行了分析. 并讨论了势能面对电荷分布的一次矩和二次矩的影响.     

中重核14.5MeV (n,2n),(n,3n)反应截面的系统学计算

本文从中子核反应机制出发,讨论(n,2n),(n,3n)反应过程,给出约化截面的计算公式.按照系统学方法计算z=58—83的53个中重核的14.5MeV (n,2n),(n,3n)反应截面,计算结果与实验值符合较好.     

Trapping of Neutral^87Rb Atoms on an Atomchip

We report an experiment of trapping of neutral ^87Rb atoms on a self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We collect 3×10^6 ^87Rb atoms in the mirror magneto-optical trap （MOT） using the external MOT coils, and 1×10^5 ^87 Rb atoms are transferred to U-MOT using U-shaped wire in chip and a pair of bias coils.     

Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

In Fourier transform profilometry (FTP), we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device (CCD) and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical explanation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.     

导体旋转椭球电学量的一种计算方法

用一种新方法，计算了孤立导体旋转椭球的面电荷密度、电容、电势和电场强度，并得出相应的解析表达式。     

亚波长光栅的偏振闪耀特性

 使用琼斯矩阵的方法推导了连续结构亚波长光栅的衍射方程,给出了光栅衍射效率表达式,对偏振特性与衍射特性进行了研究。发现连续结构亚波长光栅仅存在３个衍射级,总衍射效率为100%,且衍射效率可在衍射级间任意分配,0级的偏振态与入射光的偏振态相同,±1级衍射光偏振态与入射光无关,－1级为左旋圆偏振光,＋1级为右旋圆偏振光。通过设置入射光偏振态与光栅相位延迟等参数,可使光栅具有闪耀特性,据此可用于设计高效偏振光分束器和偏振光开关。