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在BEPCⅡ/BESⅢ上寻找η′_c和~1P_1的Monte Carlo研究
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作者 李刚 朱永生 +1 位作者 张达华 刘怀民 《高能物理与核物理》 CSCD 北大核心 2002年第7期645-651,共7页
使用SimBes(探测器模拟软件 )和UGNT(物理事例产生器 )模拟了在即将建造的BEPCⅡ BESⅢ上寻找 η′c 和1 P1 的过程 .初步结论是如果收集到 3× 1 0 9ψ( 2S) 事例 ,就有能力寻找这两个粒子 ,而且 ,寻找 η′c 比寻找1 P1 需要更少... 使用SimBes(探测器模拟软件 )和UGNT(物理事例产生器 )模拟了在即将建造的BEPCⅡ BESⅢ上寻找 η′c 和1 P1 的过程 .初步结论是如果收集到 3× 1 0 9ψ( 2S) 事例 ,就有能力寻找这两个粒子 ,而且 ,寻找 η′c 比寻找1 P1 需要更少的ψ( 2S) 展开更多
关键词 bePCⅱ/besⅲ MONTE CARLO模拟 粲偶素S波自旋单态η′ 粲偶素P波自旋单态^1P1 粒子研究 北京电子对撞机
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在BEPCⅡ/BESⅢ上寻找胶子球的Monte Carlo研究
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作者 朱莹春 沈肖雁 郑志鹏 《高能物理与核物理》 CSCD 北大核心 2003年第7期559-563,共5页
在即将建造的BEPCⅡ BESⅢ上利用MonteCarlo模拟研究了J ψ→γX→γηη′(η′→γρ0 ,ρ0 →π+ π-,η→γγ)过程 .研究显示BESⅢ的良好性能和大统计量的J ψ事例样本为寻找胶子球态的一些候选者并确认其存在提供了可能 .基于所... 在即将建造的BEPCⅡ BESⅢ上利用MonteCarlo模拟研究了J ψ→γX→γηη′(η′→γρ0 ,ρ0 →π+ π-,η→γγ)过程 .研究显示BESⅢ的良好性能和大统计量的J ψ事例样本为寻找胶子球态的一些候选者并确认其存在提供了可能 .基于所研究的衰变道 ,为BESⅢ电磁量能器晶体BGO和CsI的选择及磁场强度的选择提供了数据 . 展开更多
关键词 胶子球 MONTECARLO 蒙特卡罗模拟 QCD bePCⅱ/besⅲ 量子色动力学
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STRUCTURE DESIGN OF THE BEIJING SPECTROMETERⅢBEAM PIPE 被引量:3
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作者 ZHENG Lifang JI Quan +5 位作者 WANG Li LI xunfeng XU Shaowang DONG Sujun ZHAO Libin LIU Jianping 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第3期1-6,共6页
The Beijing spectrometer Ⅲ (BESⅢ) beam pipe is in the center of the BESⅢ, which is the detector of the upgrade project of Beijing electron and positron collider (BEPC Ⅱ). Electrons and positrons collide in the... The Beijing spectrometer Ⅲ (BESⅢ) beam pipe is in the center of the BESⅢ, which is the detector of the upgrade project of Beijing electron and positron collider (BEPC Ⅱ). Electrons and positrons collide in the BESⅢ beam pipe. According to the demands of the BEPC Ⅱ, a key program of Chinese Academy of Sciences, the BESⅢ beam pipe is designed based on the finite elements analysis. The BESIII beam pipe is installed in the inner cylinder of the BESⅢ drift chamber. As a vacuum tube, the BESIII beam pipe is designed as 1 000 mm in length, 63 mm in inner diameter and 114 mm in outer diameter, respectively. The BESIII beam pipe consists of a central beryllium pipe cooled by EDM-1, the oil No.1 for electric discharge machining, and two extended copper pipes cooled by deionized water (DW). The three parts are jointed by vacuum welding. Factors taken into account in the design are as follows. ① The wall thickness of the central beryllium pipe should be designed as small as possible to reduce the multi-scattering and improve the particle momentum resolution. And the wall thickness of the extended copper pipe should be designed as large as possible to protect the detectors from the backgrounds. ②The BESⅢ beam pipe must be sufficiently cooled to avoid the damage and prevents its influence to the BESⅢ drift chamber (DC) operation. The inner surface temperature of the DC inner cylinder must be maintained at 293±2 K. ③ The magnetic permeability of the materials used in the BESⅢ beam pipe must be less than 1.05 H/m to avoid large magnetic field distortions. ④ The static pressure of the vacuum chamber of the BESⅢ beam pipe must be less than 800 μPa. The simulating results show that the designed structure of the BESⅢ beam pipe satisfies the requirements mentioned above. The structure design scheme is evaluated and adonted hv the headouarters of BEPCⅡ. 展开更多
关键词 beam pipe beijing spectrometer Structure design beijing electron and positron collider bes
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Charmonium results from BES
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作者 平荣刚 《Chinese Physics C》 SCIE CAS CSCD 2010年第6期626-631,共6页
Using ~ 14 × 10^6 ψ(2S) and ~ 58 × 10^ J/ ψ data collected at BES Ⅱ/BEPC, the branching fraction of ψ(2S)→Ω-Ω^+ is measured with about 5a statistical significance. The A electric dipole and ∧... Using ~ 14 × 10^6 ψ(2S) and ~ 58 × 10^ J/ ψ data collected at BES Ⅱ/BEPC, the branching fraction of ψ(2S)→Ω-Ω^+ is measured with about 5a statistical significance. The A electric dipole and ∧ decay parameter are studied using the decay J/ψ →∧∧→ ppπ^+π^-. Using (106±3)× 10^6 ψ(2S) decays collected at BESⅢ/BEPC Ⅱ, we have obtained some interesting physics results. The branching fractions of XcJ→π^0π^0, ηη are measured with precision improved. The mass and width of he(l^1P1) state, together with the branching fractions of Br(ψ(2S) →π^0hc) and Br(hc →γηc) are the first measurements. Surprisingly, the decays of Xc1→φφ, ωω, and ωφ are firstly observed in BESⅢ data. 展开更多
关键词 charmonium decays J/Ψ XcJ ψ(2S) bes ⅱ/besⅲ experiment
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Online measurement of the BEPCⅡ background using RadFET dosimeters
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作者 宫辉 李金 +3 位作者 龚光华 李裕熊 侯磊 邵贝贝 《Chinese Physics C》 SCIE CAS CSCD 2009年第9期774-776,共3页
To monitor the integral dose deposited in the BESⅢ electromagnetic calorimeter whose performance degrades due to exposure to the BEPC Ⅱ background, a 400 nm IMPL RadFET dosimeter-based integral dose online monitor s... To monitor the integral dose deposited in the BESⅢ electromagnetic calorimeter whose performance degrades due to exposure to the BEPC Ⅱ 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. 展开更多
关键词 bePC background bes EMC 400 nm IMPL RadFET dosimeter TLD
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