| Project/Area Number |
15104003
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| Research Category |
Grant-in-Aid for Scientific Research (S)
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| Allocation Type | Single-year Grants |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ASAHI Koichiro Tokyo Institute of Technology, Graduate School of Science, Professor (80114354)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIDA Makoto Tokyo Institute of Technology, Graduate School of Science, Assistant Professor (90397042)
YOSHIMI Akihiro RIKEN, Nishina Accelerator Research Center, Scientist (40333314)
酒井 健二 東京工業大学, 大学院・理工学研究科, 助手 (40272661)
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| Project Period (FY) |
2003 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥98,800,000 (Direct Cost: ¥76,000,000、Indirect Cost: ¥22,800,000)
Fiscal Year 2007: ¥11,960,000 (Direct Cost: ¥9,200,000、Indirect Cost: ¥2,760,000)
Fiscal Year 2006: ¥18,720,000 (Direct Cost: ¥14,400,000、Indirect Cost: ¥4,320,000)
Fiscal Year 2005: ¥17,810,000 (Direct Cost: ¥13,700,000、Indirect Cost: ¥4,110,000)
Fiscal Year 2004: ¥22,360,000 (Direct Cost: ¥17,200,000、Indirect Cost: ¥5,160,000)
Fiscal Year 2003: ¥27,950,000 (Direct Cost: ¥21,500,000、Indirect Cost: ¥6,450,000)
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| Keywords | Electric dipole moment / CP violation / Standard model / Supersymmetric theory / Nuclear spin maser / Optical pumping / Nuclear physics / Spin polarization / 磁場の安定化 / 低周波核スピンメーザー / 磁気シールド / スピン歳差 |
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| Research Abstract |
Violation of CP invariance, known for more than 40 years in neutral K decay and recently confirmed also in B decay, remains one of vital subjects in contemporary particle physics. The standard Model (SM) includes the CP violation in a form of complex phase in the K-M matrix elements and well represents the observed flavor-changing K and B decays, but never provide a permanent electric dipole moment (EDM) of detectable size. On the other hand, models proposed beyond the SM, such as supersymmetric one, predict sizeable values for EDM, thus rendering EDM an exclusive position as a probe of physics beyond the SM. The present research has aimed at development of new scheme of nuclear spin maser that enables precision determination of spin precession frequency, in order to pave a route for ultrahigh-sensitivity search for an EDM in a ^<129>Xe atom.
^<129>Xe nuclear spins of Xe gas contained in a 22 mm-diameter glass cell were successfully polarized by spin exchange with optically pumped Rb vapor, their precession was detected by probe Laser light, and a self-sustaining precession by means of an artificial feedback was observed for the first time. The observed precision in frequency proved to improve as Δv ∝ 1/T^<1.5> as a function of the measurement time T until T = 3000 s, and then tended to be flattened. Following this result, we worked out several improvements in the setup, including the magnetic shielding, magnet current stabilization, Laser operation and wavelength stabilization, and cell temperature control, and finally attained Δv = 9.3 nHz (amounting to EDM sensitivity of Δd 〜 9×10^<-28> ecm) in a measurement time T = 30000 s. Also, a number of issues were identified that have decisive effects on the v precision and definitely deserve further work for improvement. We thus conclude that the present work has confirmed effectiveness of novel method for the atomic EDM search, and has clarified the directions that should enable the long awaited EDM precision.
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