涉铅企业周边土壤和稻谷中铅的污染现状

对涉铅企业周边土壤和稻谷进行取样调查,分别测定并分析了土壤和谷物中铅的含量.结果表明,涉铅企业周边土壤存在不同程度铅污染,涉铅企业A尤为突出.参照《食品中污染物限量》,涉铅企业A周边稻谷中存在高铅污染风险.     

Periodic Motion of Atoms Near a Charged Wire

We study the classical motion of an atom in the vicinity of an infinite straight wire which carries an oscillating uniform charge. This system has been proposed as a mechanism for trapping cold neutral atoms. The parameters of the problem are the magnitude Q and frequency of oscillation of the charge, the mass M and polarizability of the atom, and the angular momentum L of the atom about the wire. For 0 and 2MQ ² greater than, but close to, L ², we prove that the atom's radial motion is periodic (with period 2/), and that the atom moves in a helical path around the wire. For 2MQ ² L ² we prove that the atom must either collide with the wire or else escape to infinity in the radial direction.     

赝火花脉冲电子束传输中束斑分析

通过赝火花强流脉冲电子束对酸敏变色片和单晶硅的轰击试验，结合束流自箍缩效应进行理论计算，对赝火花脉冲电子束传输中束斑的变形进行了研究与分析. 结果表明椭圆形轰击束斑是由通过旁路电容的瞬态电流产生的方位角磁场所引起的，并且提出了解决束斑变形的有效方法. 关键词： 脉冲电子束 赝火花放电 束斑 自箍缩效应     

维基(Wiki)网站在物理实验教学中的作用

实验中心的网站要求展现的知识点多、更新快、功能强,是物理教学的重要组成部分.文章介绍了复旦大学物理教学实验中心使用基于维基(Wiki)的网站系统［1］在建站、运行和维护等方面的经验,以及维基网站在物理实验教学中的作用.     

Rayleigh-Taylor不稳定性的Runge-Kutta间断有限元模拟

 采用发展后的间断有限元方法,对Rayleigh-Taylor不稳定性进行了数值模拟。在计算中采用Level-Set方法进行界面追踪,用虚拟流体方法（Ghost Fluid Method,GFM）对界面附近物理量进行等压装配。对两个典型的Rayleigh-Taylor不稳定性算例的数值研究结果表明,采用该方法计算含有接触间断的多介质流体力学问题是有效的,在交界面附近不出现伪振荡,具有较高的分辨率。     

脉冲放电弧光等离子体演示仪

介绍了一种脉冲放电弧光等离子体演示仪.该设备内置的测量电路可以直接显示放电电压、电流的大小和放电的持续时间,放电电流也可以通过附带的感应线圈来测量;结合光栅光谱仪,可以测出发光光谱,进而求出等离子体的温度、密度等参数.     

多次改变聚焦强度法测量束流发射度

就“多次改变聚焦强度法测量束流发射度”,讨论了测量技术和测量装置的优化,包括薄透镜近似的合理采用,多点最小二乘拟合,截面测量靶轴向位置的优化选择,和测量软件系统的改进等,以提高发射度测量的准确性和可靠性.已将上述优化技术,应用于BEPC直线加速器上新建和改建的发射度测量装置,获得了满意的测量结果     

Measurement and folding-potential analysis of the elastic α-scattering on light nuclei

Differential cross sections ofα-elastic scattering have been measured for the target nuclei¹¹B,¹²C,¹³C,¹⁴N,¹⁵N, and¹⁶O atE=48.7 and 54.1 MeV and for the nuclei¹⁷O,¹⁸O, and²⁰Ne atE=54.1 MeV. The experimental results were analysed in terms of the optical model using different complex potentials. Special emphasis is given to the application of the double-folding approach for the real part of the potential. The imaginary part is expressed in terms of Fourier-Bessel functions. Differential cross sections for theα-¹⁶O scattering over a wide energy range and for the elasticα-scattering for nuclei in the mass rangeA=11 up toA=24 atE=54.1 MeV are analysed by this method. A close correlation between the absorptive part of the potential and nuclear deformation is observed.     

Double folding model calculation applied to fusion reactions

The interaction potential between a spherical and a deformed nucleus is calculated within the double-folding model for deformed nuclei. We solve the double folding potential numerically by using the truncated multipole expansion method. The shape, separation and orientation dependence of the interaction potential, fusion cross section and barrier distribution of the system ¹⁶O+¹⁵⁴Sm are investigated by considering the quadrupole and hexadecapole deformations of ¹⁵⁴Sm. It is shown that the height and the position of the barrier depend strongly on the deformation and the orientation angles of the deformed nucleus. These are quite important quantities for heavy-ion fusion reactions, and hence produce great effects on the fusion cross section and barrier distribution.     

光盘结构及实验中的光学现象

用胶带将CD-R的数据记录层和树脂层分离,分别用扫描电子显微镜和光学实验方法研究了光盘数据记录层的结构,测量了光盘径向的光道间距,计算出光盘的容量.实验中观察到了衍射亮点,其成因是光在金属印刷层与树脂层之间的多次反射和衍射.