Calibration study of the X-T relation for the BESⅢ drift chamber

Offline calibration plays an important role in BES offline data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BES drift chamber. This paper studies the time-to-distance relations, which are important calibration constants for track reconstruction. The parameterization of the time-to-distance relation, studies of left-right asymmetry and studies of variation with entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shift in measured momentum for tracks passing near dead cells. Finally we present the resolutions for barrel Bhabha events(|cos θ|< 0.8) from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 Ge V/c Bhabha tracks is 11.9 Me V/c.     

用NMR谱研究乙酸甲酯的水解反应

用ＮＭＲ谱研究乙酸甲酯的水解反应邵振忠，李卫东（北京师范大学化学系１００８７５）核磁共振除广泛用于有机化学、生物、医药等各个领域外，从６０年代开始在化学动力学方面显示身手，本文用目前很多高校具有的６０兆ＮＭＲ谱仪来测定乙酸甲酯在不同温度下水解反应速率...     

聚苯乙烯-乙丙共聚物两嵌段共聚物的组成分析

本文用红外光谱(IR)的工作曲线法及傅里叶变换红外光谱(FT-IR)差谱法,分析了多单体嵌段共聚物聚苯乙烯-乙丙共聚物PS-b-EPR的组成,包括聚苯乙烯段的含量和乙丙共聚物段的乙丙组成。     

Lewis酸性Mg(II)在有机合成中的应用

综述了Lewis酸性的Mg(II)及其配合物在有机官司能团转化和碳——碳键形成 反应中的应用。较强的Lewis酸性、较强的亲氧性和较高的配位数对Mg~(2+)独特的 催化反应活性起着关键的作用。     

呋喃西松烷型二萜内酯的研究进展

概述了呋喃西松烷型二萜内酯类化合物的分离、结构特点及其生理活性,总结了近十几年来几个研究小组进行的呋喃西松烷型二萜内酯类化合物的全合成研究进展及成果.     

Stability Diagrams of a Bose-Einstein Condensate in a Periodic Array of Quantum Wells

With the help of a set of exact closed-form solutions to the stationary Gross Pitaevskii equation, we compre-hensively investigate Landau and dynamical instabilities of a Bose-Einstein condensate in a periodic array of quantum wells. In the tight-binding limit, the anaiyticai expressions for both Landau and dynamical instabilities are obtained in terms of the compressibility and effective mass of the BEC system. Then the stability phase diagrams are shown to be similar to the one in the case of the sinusoidal optical lattice.     

Track reconstruction using the TSF method for the BESⅢ main drift chamber

We describe the algorithm to reconstruct the charged tracks for BESⅢ main drift chamber at BEPCⅡ, including the track finding and fitting. With a new method of the Track Segment Finder (TSF), the results of present study indicate that the algorithm can reconstruct the charged tracks over a wide range of momentum with high efficiency, while improving the robustness against the background noise in the drift chamber. The overall performances, including spatial resolution, momentum resolution and secondary vertices reconstruction efficiency, etc. satisfy the requirements of BESⅢ experiment.     

基于量子Fisher信息的量子计量进展

量子计量是超冷原子气体研究中的一个热点领域.超冷原子体系独特的量子性质(量子纠缠)和量子效应有助于大幅度提高待测物理量的测量精度,这已经成为量子精密测量中的共识.量子Fisher信息对该领域的发展起了非常重要的作用.本文首先介绍量子Fisher信息的基本概念和量子计量的主要内容;然后简要回顾这些理论在提高测量精度方面的应用,特别是多粒子量子纠缠态的产生及其判定;再介绍线性和非线性原子干涉仪的相关进展;最后论述量子测量过程中的统计方法的研究进展.     

Relative Phase with the Overlap Region of Two Bose—Einstein COndensates

We present an expression of the relative phase for two interacting Bose-Einstein condensates released from an isotropic trapping potential.We discuss the interference condition between condensates and the visibility of the interference pattern reflecting the interaction between the condensates.