Investigation into Inner Structure of Nucleon through International Collaboration

通过国际合作研究核子的内部结构

• 批准号: 12800008
• 负责人: HORIKAWA Naoaki
• 金额: $ 13.06万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Special Purposes
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12800008/
• 关键词: spin; structure of the nucleon spin; COMPASS; polarized target; gluon spin; COMPASS; クオークスピン; QCD; ミューオンビーム

The international collaboration research "COMPASS" is now going on as one of the international contributions from Japan to world wide activities in the field of science and engineering. COMPASS beam time has been scheduled on May 27, 2002, and started the measurement from middle July after the installation of the detectors which had not been prepared and the final tuning of all the equipments. The measurement has ended on September 23 after taking the physics data 5x10^9 events. Those data are now on the way of analysis. For the execution of the long term run, we sent two students for full time of the experiment and one student for two months for the start-up of the polarized target system. The staff members visited CERN alternately to take shifts of the experiment and to guide the students during their long term stay.(1) The construction of the polarized target system for COMPASS experiment :For the polarizing magnet, we used the old SMC magnet because the COMPASS magnet was not ready … More for the installation. We decided to move the COMPASS magnet to other company called Oxford Danphysik(OD), which is organized by the former Oxford staffs for the rewinding the solenoid coil, after the discussions among Nagoya-group, COMPASS CERN and Oxford Instrument Co. LTD. The solenoid will be reconstructed taking the advices given by the Japanese and French specialists of the superconducting magnet. By the reassemble of the magnet at OD, it has been made clear that there are some problems like insufficient impregnation of the coil and wiring and so on. After the summary of problems found on the coil, the new design will be prepared and the re-fabrication will start. We estimate the completion of the magnet in late autumn of 2003.(2) The fabrication and utilization of the scintillating fiber tracker :We constructed four sets of beam tracker detector composed of the scintillating fiber with a diameter of 0.5 mm and the photomultiplier with 16 channel photocathodes(Hamamatsu : H6568). The tracker worked very well under the beam condition of 160GeV and 1.4x10^8/ppp, which gives the counting rate 4MHz to the central one channel. Against this overwhelmingly severe condition, the tracker gave the satisfactory performance like, less than 500ps for time resolution, 130μm for position resolution, more than 96% for the detection efficiency and 1.01 for multiplicity. The reliable performance of the tracker has been used as a reference detector to other detectors for the timing tuning and efficiency tuning etc.(3) The execution of the measurementThe experimental run started about the middle of July and ended on September 23. During the experiment, we accumulated the data for the longitudinal polarization asymmetry by 57 days and obtained the events for 173kspills. For the transversity measurement, we took the data for 19 days and obtained the data for 52 kspills.The registered events reached to 5 Gevents.The D^0 events which contribute to the determination of gluon polarization are estimated to be 29,000 events, and the D^* events are estimated to be 3,800 events. We will report the ΔG/G result, as soon as possible, after the analysis. Less

国际合作研究“COMPASS”目前正在进行，这是日本对世界科学和工程领域活动的国际贡献之一。COMPASS束流时间安排在2002年5月27日，在安装了尚未准备好的探测器和所有设备的最后调试之后，从7月中旬开始测量。测量于9月23日结束，获得了5x10^9个事件的物理数据。这些数据正在分析中。为了长期运行的执行，我们派出两名学生进行实验的全职和一名学生两个月的极化目标系统的启动。工作人员轮流访问欧洲核子研究中心，轮流进行实验，并在学生长期逗留期间指导他们。(1)COMPASS实验中极化靶系统的构建：对于极化磁体，由于COMPASS磁体还没有准备好，我们使用了旧的SMC磁体 ...更多信息 为了安装。在名古屋集团、COMPASS CERN和Oxford Instrument Co. Ltd.讨论后，我们决定将COMPASS磁体转移到另一家名为Oxford Danphysik（OD）的公司，该公司由前牛津员工组织，用于重新缠绕螺线管线圈。通过OD处磁体的重新组装，已经明确存在线圈浸渍不足和布线等问题，在总结线圈上发现的问题后，将准备新的设计并开始重新制造。我们预计磁铁在2003年秋末完成。(2)光纤跟踪器的制作和应用：我们用直径为0.5mm的光纤和16通道光电阴极光电倍增管（Hamamatsu：H6568）组成了四套光束跟踪器探测器。在160 GeV和1.4 × 10 ~（^8）/ppp的束流条件下，跟踪器工作良好，中心一通道计数率为4 MHz。在这种极端恶劣的条件下，该跟踪器的时间分辨率小于500 ps，位置分辨率为130μm，探测效率大于96%，多重性为1.01。该跟踪器性能可靠，可作为其它检测器的定时调谐和效率调谐等参考检测器。(3)测量的执行实验运行大约从7月中旬开始，到9月23日结束。在实验过程中，我们积累了57天的纵向偏振不对称数据，并获得了173 kspls的事件。在横度测量中，我们进行了19天的观测，获得了52 ksplls的数据，记录的事件数达到了5 G个，对胶子极化有贡献的D^0事件估计为29，000个，D^* 事件估计为3，800个。我们将在分析后尽快报告ΔG/G结果。少

项目成果

堀川 直顕 他SMCメンバー: "Measurement of the SMC Muon Beam Polarization Using the Asymmetry in the Elastic Scattering off Polarized Electron"Nucl.Instrum.Methods in Phys.Research. A443. 1-19 (2000)

Naoaki Horikawa 和其他 SMC 成员：“利用极化电子弹性散射的不对称性测量 SMC Mu 子束极化”Nucl.Instrum.Methods in Phys.Research 1-19 (2000)。

S.Horikawa, et al.: "A Scintillating Fiber Tracker with High Time Resolution for High-Rate Experiments"IEEE Transactions on Nuclear Science. Vol. 49, No. 3. 950-956 (2002)

S.Horikawa 等人：“用于高速率实验的具有高时间分辨率的闪烁光纤跟踪器”IEEE Transactions on Nuclear Science。

T. Toeda, et al.: "Conditions database system of the COMPASS experiment"Computer Physics Communications. 152. 135-143 (2003)

T. Toeda 等人：“COMPASS 实验的条件数据库系统”计算机物理通讯。

S.Horikawa, et al.: "A Scintillating Fiber Tracker with High Time Resolution for High-Rate Experiments"IEEE Transactions on Nuclear Science. 49. 950-956 (2002)

S.Horikawa 等人：“用于高速率实验的具有高时间分辨率的闪烁光纤跟踪器”IEEE Transactions on Nuclear Science。

J.Ahrens, et al.: "The helicity amplitudes A_<1/2> and A_<3/2> for the D_<13> resonance obtained from the γ^^→p^^→→pπ^0 reaction"Phys. Rev. Lett.. 88. 232002 (2002)

J.Ahrens 等人：“从 γ^^→p^^→→pπ^0 反应获得的 D_<13> 共振的螺旋幅度 A_<1/2> 和 A_<3/2>”Phys Rev. Lett.. 88. 232002 (2002)