原子受激态的Stokes参数分析

根据密度矩阵理论,导出了受激原子态P态密度矩阵元和P态退激辐射的光子密度矩阵元的Stokes参数,它们之间存在一种非常简单直接的关系,说明在电子-光子符合散射实验中,通过测量光子的Stokes参数,就可以描述受激P态电荷云分布和散射过程的动力学。According to the density matrix theory, the density matrix of photon emitted from excited atom P state and of P state were introdued in this paper. There were a simple direct relation between the two density matrices, which shows that the electron cloud shape of excited atomic state and scattering dynamics can be described through the observable Stokes parameters of photon in electron-photon coincidence experiment.     

Passive magnetic shielded spin polarized electron source with optical electron polarimeter

A new GaAs(100) spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel--iron--molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5×10^-7,T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95cm distance through an 1mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8\pm3.5% measured with a He optical polarimeter.     

Characterization of large area photomultiplier ETL 9357FLB for liquid argon detector

The China Dark Matter Experiment (CDEX) Collaboration will carry out a direct search for weakly interacting massive particles with germanium detectors. Liquid argon will be utilized as an anti-Compton and cooling material for the germanium detectors. A low-background and large-area photomultiplier tube (PMT) immersed in liquid argon will be used to read out the light signal from the argon. In this paper we have carried out a careful evaluation on the performance of the PMT operating at both room and cryogenic temperatures. Based on the single photoelectron response model, the absolute gain and resolution of the PMT were measured. This has laid a foundation for PMT selection, calibration and signal analysis in the forthcoming CDEX experiments.     

核工程类专业引导课中的大学物理图解

核工程类专业是基于核科学与技术学科,面向核能与核技术行业领域人才培养需要而设置的本科类专业.物理学是核科学与技术的起源,大学物理是核工程类专业的重要基础课程.为此,在核工程类专业引导课上,构思和设计大学物理知识的溯源、建立与发展的图解,以帮助学生建立大学物理的知识框架,激发学习兴趣,科学合理规划学习安排.     

生物物理的发展与前景

 物理学是研究自然界物质结构及运动规律的学科,是自然科学的基础,是一门既古老又“摩登”的学科。     

B2H6分子结构和振动频率的DFT研究

用密度泛函理论(DFT)方法研究B2H6分子的几何结构、空间电子密度分布和轨道动量分布以及振动频率等基本性质.取DFT理论中的B3LYP方法和6-311++G* *基组对乙硼烷分子的几何构型进行全优化计算后分析其空间电子密度分布.利用不同方法和基组得到了轨道动量分布.在B3LYP/6-311++G* *基础上对优化后的结构进行正则振动频率分析.     

基于电子动量谱学的正戊烷分子构象分析

本文对正戊烷(n-pentane)分子构象进行了理论研究，给出了不同构象分子价轨道的能级分布和电子动量分布，进而分析引入电子动量谱学(EMS)作为一种新的实验探测手段，把电子动量谱学推向有机分子构象研究领域。     

奇妙的光学陷阱

 科技的迅猛发展给地球上的人类生活带来令人眩目的变化,古人的梦想例如“千里眼,千里耳”在今天已经实现。现在的人类梦想在将来也许有一天会实现。科幻小说伽莫夫的《物理世界奇遇记》里描述的一段:汤普金斯先生来到一座神奇的城市,由于这城市的光速异乎寻常的小,当他骑自行车高速行驶时,发现周围的一切都变扁了。自从爱因斯坦的狭义相对论成立以来,上面的描述被认为是正确的。但它的前提是光速非常小,自行车速都能超过,这看起来有点玄乎。据最近报道,英国皇家科学院的科学家用光学陷阱里的冷原子来捕获光子,使光速减慢为17ｍｓ,是真空中的光速3×108ｍｓ的2亿分之一,简直不可思议。     

椭偏技术研究肌纤维运动分子动力学

肌肉细胞即肌纤维,含大量纵向排列的肌原纤维,由粗肌丝和细肌丝(主要成分是肌球蛋白和肌动蛋白分子)组成的肌原纤维具有特征性的带状结构,呈各向异性,伸缩时具有变化的双折射性.线偏振光通过肌纤维,会退偏为椭偏光,根据退偏的程度,可以研究肌纤维结构的变化.     

物理学志愿者——核物理学家迈耶

 玛丽亚·戈伯特·迈耶,著名物理学家,诺贝尔物理学奖获得者.本文记述了她的生平以及在受到歧视几十年里对科学的执着追求.为当代物理学的发展作出了杰出的贡献,成为世界妇女的楷模.