Electron-Positron Collision Experiment with SLAC・SLD Detector

为了对粒子物理中的“标准模型”进行详细的检验，在SLAC直线对撞机(SLC)的e^+e^-束撞点上建造并安装了SLAC大探测器(SLD)。实验的目标是积累10^4到10^5个Z^0粒子，其中“极化电子束”和“正电子束”的碰撞能量约为92GeV。1989年至1991年，日本团体与SLAC A组和B组合作，参与了中央漂移室(CDC)和克伦科夫环成像探测器(CRID)的建造和运行。这次实验的独特之处在于，首次利用了为电弱理论的关键参数Sin^2hita_W(Rheta_lt；W‘&gt；Weinberg角)提供100多倍灵敏度的“偏振电子束”，通过总截面的正反向不对称。与现有的其他探测器相比，SLD/SLC实验的优点是：碰撞点的束流尺寸较小，顶点确定…精确更多的是由顶点探测器(VTX)、中央漂移室(CDC)的FME轨迹确定、切伦科夫环成像探测器(CRID)良好的粒子识别以及液体Ar电磁(LAC)和气体采样强子量热仪(WIC)的良好量热。探测器于1990年春完工，并于1990年夏季至秋季用宇宙射线进行了全面测试，并于1991年2月转移到切割位置。第一次束流试验是在1999年4月至7月进行的。在这次试验中，加速器进行了调整，以提供更高的强度，而不是偏振束流。在这些试运行后，探测器的一些剩余部件已在夏季停机期间安装完毕。从10月中旬到1991年底，以每秒60个脉冲的束流工作模式成功地完成了工程运行。通过103小时的净数据采集，共获得363次Z^0事件，其中总的束流准时为170小时。实验结果表明，CDC跟踪分辨率局部位置分辨率为97 mm，整体分辨率为123 mm。后者可以通过进一步的微电池位置校准调整到35 mm。1991年8月，CRID获得了第一张宇宙粒子通过的切伦科夫环图像，驯服气体混合到复杂的气体循环系统中完全成功。我们希望从高强度开始的10^4 Z^0的修正是以50 Z^0 S/小时(重复频率120 HZ)进行的，计划在1992年3-7月和10-12月进行，光束偏振度约为35%。名古屋大学和东北大学的计算机安装和数据分析准备工作已经就绪。较少

To proceed a detailed examination of "the standard model" in particle physics, the SLAC Large Detector (SLD) has been constructed and installed in the e^+e^- beam-collision point in the SLAC Linear Collider (SLC). The goal of experiment is to accumulate 10^4 to 10^5 Z^0 events with collision of "polarized electron beam" and "positron beam" at around 92 GeV. Japanese Group took parts in the construction and operation of Central Drift Chamber (CDC) and Crrenkov Ring Imaging Detector (CRID) from 1989 to 1991 under the cooperation with SLAC Group A and Group B.The unique feature of this experiment is that the first utilization of "Polarized electron beam" which provides more than 100 times sensitivity for sin^2rheta_W (rheta_<W'>Weinberg-angle), a key parameter of the electroweak theory, through the forward-backward asymmetry of total crosssections. The vantages of SLD/SLC experiment over other existing detectors are : a smaller beam size at collision point, a precise vertex determination … More by Vertex Detector (VTX), fme track determination by Central Drift Chamber (CDC), good particle identification with Cerenkov Ring Imaging Detector (CRID) and good calorimetry with liquid argon electromagnetic (LAC) and gas-sampling hadron calorimeters (WIC).The detector was completed in the Spring of 1990 and thoroughly tested with cosmic-rays from Summer to Fall in 1990, and was moved into the hewn position in February 1991. First test runs with beam was made from April to July 199 1. In this run, accelerator was tuned to provide higher intensities without polarized beam. After these test runs, some remaining parts of the detector had been installed in the period of Summer shutdown. The engineering runs were successfully done from the middle of October to the end of 1991 with beams of 60 pulses per second operation mode. We obtained total of 363 Z^0 events by net data acquisition time of 103hr., where the total beam on time was 170hr. and detector on time was 130hr.From these experiments, CDC tracking resolutions were turned out to be 97mm in local position resolution and 123mm in overall resolutions. The latter could be tuned up to 35mm by further position calibrations of mini-cells. CRID obtained first Cerenkov ring image for passage of cosmic particles in August 1991 and TAME gas mixing into the complex gas-circulating system was fully successful. We hope correction of 10^4 Z^0s from the high intensity runs at 50 Z^0 s/hour rate (repetition rate of 12OHz) scheduled from March to July 1992 and from October to December 199 1, with the beam polarization of about 35%. Computer setup and preparation for data analysis are ready in Nagoya and Tohoku Universities. Less