Study of CP Violation in Weak Interaction

弱相互作用中CP破坏的研究

• 批准号: 04402006
• 负责人: NAGASHIMA Yorikiyo
• 金额: $ 21.12万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04402006/
• 关键词: Weak interaction; CP violation; Neutral kaon; CsI,photomultiplier; Data acquisition system; Photon veto counter; ガンマ線検出器; 光電子増倍管; 稀崩壊; CsIカロリメータ

We have analyzed the data from Fermilab E731 experiment, and published the final result on the CP violation parameter, Re (epsilon'/epsilon). We have also analyzed the data from Fermilab E799-I experiment, whose purpose was to search for many rare K_L decays. We have published new results on K_L*pi^0ee, K_L*pi^0mumu, K_L*pi^0nunu, K_L*eeee, K_L*eegammagamma, K_L*pi^0pi^0gamma, pi^0*ee, and pi^0*mue. The first three decays are expeted to have a large direct CP violation amplitude.9.2.Preparation of Fermilab KTeV experimentFermilab KTeV experiment will begin in July of 1996, and will run for 2 years. The experiment will measure the CP violation parameter Re (epsilon'/epsilon) with 6 times better accuracy, to 1x10^<-4>. It will also search for many rare K_L decays with a sensitively improved by two orders of magnitudes. We have made the following contributions to the experiment.*We have worked UCLA and Hamamatsu Photonics to develop a new type of phototubes for the new CsI calorimeter. The tube was designed to have an excellent linearity. We built a new phototube testing system, and measured the linearity and rate dependence of the 2400 tubes with <0.2% accuracy.*We have collaborated with Fermilab to develop a new data acquisition system. The system consists of a large memory matrix and high performance computers. This system can read in and fully analyze 8kbyte events coming at 20kHz, and write out selected events to tape.*We have designed, tested, and produced a specialized photon veto counter to be placed around the beam holes in the CsI calorimeter.*We have estimated the sensitivity and background levels for various rare K_L decays by using Monte Carlo simulation. We have also developped analysis codes for the decays.

我们分析了Fermilab E731实验的数据，并公布了CP破坏参数Re（ε ′/ε）的最终结果。我们还分析了Fermilab E799-I实验的数据，该实验的目的是寻找许多罕见的K_L衰变。我们已经发表了关于K_L*pi^0ee，K_L*pi^0mumu，K_L *pi^0nunu，K_L*eeee，K_L*eegammagamma，K_L*pi^0pi^0gamma，pi^0*ee和pi^0*mue的新结果。9.2.费米实验室KTeV实验的准备费米实验室KTeV实验将于1996年7月开始，运行时间为2年。该实验将测量CP破坏参数Re（ε ′/ε ′），其精度提高6倍，达到1 × 10 - 4<-4>。它也将搜索许多稀有的K_L衰变，灵敏度提高了两个数量级。我们对实验作出了以下贡献。我们与UCLA和滨松光子学公司合作，为新的CsI量热计开发一种新型光电管。该管的设计具有出色的线性度。我们建立了一个新的光电管测试系统，并测量了2400管的线性度和速率依赖性，精度&lt;0.2%。我们与费米实验室合作开发了一种新的数据采集系统。该系统由一个大型存储矩阵和高性能计算机组成。该系统可以读入并全面分析以20 kHz频率传入的8 kbyte事件，并将选定的事件写入磁带。*我们设计、测试并制造了一个专门的光子否决计数器，放置在CsI量热计的束孔周围。本文用蒙特卡罗模拟方法估算了各种稀有K_L衰变的灵敏度和本底能级。我们还开发了衰变的分析代码。

项目成果

T. Nakaya, et al.: "Measurement of the Branching Ratio of K_L→e^+e^-γγ" Phys. Rev. Lett.73. 2169-2173 (1994)

T. Nakaya 等人：“K_L→e^+e^-γγ 的分支比的测量”Phys Rev. Lett.73 (1994)。

D.Roberts et al.: "Search for the decay K_L*pi^0pi^0gamma" Phys.Rev.D50. 1874-1878 (1994)

D.Roberts 等人：“搜索衰变 K_L*pi^0pi^0gamma”Phys.Rev.D50。

S.V.Somalwar et al.: "A Measurement of the Quadratic Slope Parameter in the K_L*3pi^0 Decay Dalitz Plot" Phys.Rev.Lett.68. 2580-2583 (1992)

S.V.Somalwar 等人：“K_L*3pi^0 衰变 Dalitz 图中二次斜率参数的测量”Phys.Rev.Lett.68。

K.S.McFarland: "A Measurement of the Branching Ratio of π^0e^+e^- Using Decays in Flight of K_L→π^0π^0π^0" Physical Review Letters. 71. 31-34 (1993)

K.S.McFarland：“使用 K_L→π^0π^0π^0 飞行中的衰变测量 π^0e^+e^- 的分支比”《物理评论快报》71. 31-34 (1993)。

M.B.Spencer,et al.: "Measurement of the Branching Ratio and Form-Factor of K_L→μ^+μ^-γ" Phys.Rev.Lett.74. 3323-3326 (1995)

M.B. Spencer 等人：“K_L→μ^+μ^-γ 的分支比和形状因子的测量”Phys.Rev.Lett.74 (1995)。