Coolant choice for the central beryllium pipe of the BESⅢ beam pipe

In order to take away much more heat on the BESⅢ beam pipe to guarantee the normal particle detection,EDM-1(oil No.1 for electric discharge machining),with good thermal and flow properties was selected as the candidate coolant for the central beryllium pipe of the BESⅢ beam pipe.Its cooling character was studied and dynamic corrosion experiment was undertaken to examine its corrosion on beryllium.The experiment results show that EDM-1 would corrode the beryllium 19.9 μm in the depth in 10 years,which is weak and can be neglected.Finite element simulation and experiment research were taken to check the cooling capacity of EDM-1.The results show that EDM-1 can meet the cooling requirement of the central beryllium pipe.Now EDM-1 is being used to cool the central beryllium pipe of the BESⅢ beam pipe.     

BES Physical Analyzing Environment Composed of PC Farm

This note describes the construction of hardware and software of the BESPC-FARM and BES offline data analysis environment in Linux platform.The job management packages NQS is described.The performance of the BESPCFARM also be presented.     

Online measurement of the BEPC Ⅱ background using RadFET dosimeters

To monitor the integral dose deposited in the BESⅢ electromagnetic calorimeter whose perfor-mance degrades due to exposure to the BEPCⅡ background, a 400 nm IMPL RadFET dosimeter-based integral dose online monitor system is built. After calibration with the 60Co source and verification with TLD in the pulse radiation fields, an experiment was arranged to measure the BEPC Ⅱ background online. The results are presented.     

A Model of BES Data Storage Management System

In this article we will introduce the system structure of a model built for BES data management and storage as well as the basic methods on how to establish the system.Additionally the analysis of the data structure,the data process,the selection of experimental program,the image manipulation and the key techniques will be discussed in detail,The model implements the setup of the system environment and all those functions from data loading,database cresting,data accessing,remote data process to data figuring.     

北京谱仪Ds物理研究新进展

简要介绍了北京谱仪Ｄｓ物理研究的背景,北京谱仪和北京正负电子地撞机已取得的几项物理结果的内容,及其对国际粒子物理研究的贡献。     

“伏—安法测电阻”实验的改进

1　伏安法测电阻实验的改进1.1　改进后的电路图如图 1所示1.2　改进实验的思路 :1如图 1a所示是电流计外接法的改装电路图 ,把原来的电压计换成一个微安计和一个电阻 Rf 的串联 ,实际上就是经过改装的电压计 ,利用此电路可直接在微安计中读出分路电流 IV,在改装后的刻度中读出     

北京谱仪（BESⅡ）上p和p^－鉴别的研究

以北京谱仪(BES)上常用的3种粒子鉴别方法为基础，充分利用BESⅡ所获取的R值扫描、J／ψ和ψ’数据中p，p^-以及其他带电粒子样本，对动量范围在0．3-1．2GeV的p和p鉴别方法进行分析研究．找到BESⅡ上p和p^-的最佳鉴别方法：动量低于0．6GeV只用dE／dx实现粒子鉴别，动量高于0．6GeV可用TOF或联合鉴别的方法，并给出p，p^-的鉴别效率以及本底的混入比例．     

LP—1激光功率计原理及其在物理实验中的应用

在光学实验中有很多需要测量光强的实验,如光度测量、光学成象系统的照度、菲涅耳衍射的光强分布、偏振光的研究、迈克尔逊干涉仪测量光源的相干长度、菲涅耳公式的研究等。常用的测光元件有光敏电阻、硒光电池、硅光电二极管和光电倍增管。光敏电阻的线性较差,仅在弱光和小范围(如一个数量级)内光电导和照度之间可作线性     

用PC—1500制作的高精度数据采集与处理单元

一、前言数据采集是控制系统的第一道大门,也是实验室实现自动化的第一关。在物理实验中的许多场合,会遇到要求能分辨到点几毫伏的电信号,通常一些学校都是用较好一点的电位差计或数字电压表进行测量。由于测量速度低,这就大大限制了学生对物理对象进行深入探索和研究的积极性。为了使学生把主要精力放在考查物理现象或过程的本质和规律方而,增加他们发挥主观能动性和创造性的机会,培养他们对物理实验的兴趣,本文提供一个用PC—1500制作的高精度数据采集与处理单元。 PC—1500计算机是一种8位并行运算     

K*(892)电磁质量反常(英文)

电中性的 K* (892 )电磁质量可以大于带电荷的 K* (892 ) .这是异乎寻常的现象 ,将被称为K* -电磁质量反常 .评述了这个课题 ,并指出 K* 的质量劈裂可以在北京谱仪 (BES)上作精密测量. Electromagnetic masses of neutral K *(892) may be larger than one of charged K *(892). It is unusual and is called K *-EM-mass anomaly. We review the studies on this issue, and point out that K *-mass splitting can be measured in BES accurately.     

在BES实验中用神经元网络法鉴别e,μ,π

研究了两种不同的神经元网络法,BP网络和LVQ网络,对北京谱仪(BES)实验中e,μ,π粒子的鉴别,取得了较常规方法要好的结果.用于训练和检验的μ子样本来自宇宙线事例,e和π粒子则是由真实实验数据精选的,虽然样本本身具有非均匀的动量谱,但BP网络的检验结果给出的粒子选择效率在整个动量区间却仍然具有相当均匀的分布,LVQ网络稍逊之.至少是在我们研究的这一课题中证明了BP网络的模式识别功能要优于LVQ网络.     

Charmonium results from BES

Using ～14×106ψ(2S) and ～58×106J/ψ data collected at BESⅡ/BEPC,the branching fraction of ψ(2S) →Ω+Ωˉ+ is measured with about 5σ statistical significance.The Λ electric dipole and Λ decay parameter are studied using the decay J/ψ→ΛΛ→ ppˉπ+π-.Using(106±3)×106 ψ(2S) decays collected at BESⅢ/BEPCⅡ,we have obtained some interesting physics results.The branching fractions of χcJ →π0π0,ηη are measured with precision improved.The mass and width of hc(11P1) state,together with the branching fractions of Br(ψ(2S) →π0hc) and Br(hc →γηc) are the first measurements.Surprisingly,the decays of χc1 →φφ,ωω,and ωφ are firstly observed in BESⅢ data.     

法布里—珀罗干涉仪实验中几个问题的讨论

一、引言法布里一拍罗于涉仪实验（以下简称F－P实验）是一个典型的等倾干涉实验，其干涉花样比牛顿环实验更清晰、更细锐．因其调节有一定难度，某些实验者往往将精力主要集中于调节上，忽略了一些值得讨论的问题．本文现对以下三个问题进行讨论：1．干涉环的宽度；2．测量误差；3．从第几圈干涉花样开始测量比较合理，以及至何时第一圈干涉花样算形成完整．二、F－P实验中的光强分布因为光的干涉花样是光强分市的表现，所以，对上述三个问题的讨论应从光强分布公式”‘的讨论入手，式中I0为入射光强，R为F－P标准具镀银面的反射系数；…     

α粒子散射实验与原子核的发现——"最美丽"的十大物理实验之三

1实验背景 自1897年汤姆孙(J.J.Thomson 1856～1940年)从实验中发现电子;1896年亨利·贝克勒(H.A.Becquere1 1852～1908年)发现铀的放射性现象;1898年居里夫人(M.Curie 1867～1934年)发现镭的放射性现象;1897年卢瑟福(E.Rutherford 1871～1937年,英藉新西兰人)发现放射性中的α射线和β射线;1900年维拉德(P.U.Villard 1860～1934年)发现放射性中第三种射线--γ射线以后,使人们认识到原子是可分的,原子是有结构的.因此,各国物理学家们便开始探索原子的复杂结构.     

Event generators at BESⅢ

We present a brief remark and introduction to event generators for tau-charm physics currently used at BESⅢ,including KKMC,BesEvtGen,Bhlumi,Bhwide,Babayaga and inclusive Monte-Carlo event generators.This paper provides basic information on event generators for BESⅢ users.     

RL—C并联谐振实验深入研究

针对电磁学实验中RL－C并联谐振实验，谐振时实际测量的频率与理论计算结果总是存在着一定偏差，系统地分析了其起因。     

Calibration of RPC-based muon detector at BESⅢ

The calibration algorithm for RPC-based muon detector at BESⅢ has been developed. The calibration method, calibration error and algorithm performance are studied. The primary results of efficiency and noise at layer, module and strip levels have been calibrated with cosmic ray data. The calibration constants are available for simulation and reconstruction tuning. The results of Monte Carlo and data are also compared to check the validation and reliability of the algorithm.     

Lagrange multiplier method used in BESⅢ kinematic fitting

In this paper,the kinematic fitting with the Lagrange multiplier method has been studied for BESⅢ experiment.First we introduce the Lagrange multiplier method and implement kinematic constraints.Then we present the performance of the kinematic fitting algorithm.With the kinematic fitting,we can improve the resolution of track parameters and reduce the background.