| Project/Area Number |
04804016
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | National Laboratory for High Energy Physics(KEK) |
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Principal Investigator |
OHSHIMA Takayoshi National Laboratory for High Energy Physics(KEK), Assistant Professor, 物理研究部, 助教授 (00134651)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Hiroshi Physics Department, Kyoto University, Assistant Professor, 理学部・物理, 助教授 (80178574)
SHIRAI Junpei National Laboratory for High Energy Physics(KEK), Assistant, 物理研究部, 助手 (90171032)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1993: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1992: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | phi-Factory / CP violation / K-meson decay / PHIファクトリー / φ-ファクトリー |
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| Research Abstract |
A phi-factory is a 500 MeVx500 Mev e^+e^- colliding machine facility being considered for studying the nature's discrete space-time symmetries, especially CP and CPT violations, through precise measurements of kaon-decays. The scope of this work is to examine a detector system for such an experimentation.
It comprises only two main elements : a tracking chmber and a fine-sampling type shower counter. the system is made to be quite simple and would require very moderate performances : the momentum resolution is (〕SY.upper filled triangle.〔)p/p =3% for chrged particles ; the photon energy and impact position resolutions are sigma/E = 9%/(〕SY.sqroot.〔)and-1mm, respectively. The shoer counter functions also as a range counter and provides pi/mu/e separation with the separability of 1% and detection efficiency of (〕SY.gtoreq.〔)80%.
Peculiar kinematical features at a phi-factory are efficiently applied for discriminating signals very high purity. The latest samples are used to precisely calibrate the detector performances and to further subtract the background contaminations in selected signals.
It is concluded that with our detector system the most severe backgrounds such as 3piﾟ, pi^+pi^-piﾟ, piiotanu against the signals of 2piﾟ and pi^+pi^- can be suppressed below the level of (〕SY.upper filled triangle.〔)Re(epsilon'/epsilon) = (〕SY.+-.〔)1x10^<-4>. Also, direct CP violation of the charged kaon decays will be the first ever investigated with a sensitivity of better than 1x10^<-4> in terms of a double ratio among K^<(〕SY.+-.〔)> -> 3phi's.
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