| Project/Area Number |
11640297
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | High Energy Accelerator Research Organization |
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Principal Investigator |
HIRAMATSU Shigenori High Energy Accelerator Research Organization, Accelerator Laboratory, Professor, 加速器研究施設, 教授 (00011742)
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| Co-Investigator(Kenkyū-buntansha) |
MASUZAWA Mika High Energy Accelerator Research Organization, Accelerator Laboratory, Research Associate, 加速器研究施設, 助手 (10290850)
FUKUMA Hitoshi High Energy Accelerator Research Organization, Accelerator Laboratory, Assistant Professor, 加速器研究施設, 助教授 (40150007)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | NMR / Nucler Magnetic Resonance / Spin-echo / Magnetic field measurement / Magnet / Accelerator / 核〓気共鳴 / フィールドメータ / 磁場測定 |
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| Research Abstract |
Until now it has been concerned impossible to apply the NMR technique to the precise measurement of high-gradient magnetic fields such as in quadrupole magnets use in accelerators. To overcome difficulties due to the field gradient, we have developed the spin-echo NMR technique for magnetic field measurement where the spin precession frequency in the spin-echo signal is detected.
Simulation studies of spin-echo signal detection and the theoretical signal-to-noise ratio of the spin-echo spectrum predict the possibility of spin-echo signal observation in a high-gradient magnetic field. In an experiment based on theoretical studies, we observed spin-echo signals clearly at a field strength of 2.35kG with a gradient of up to 0.55T/m using a simple fixed frequency spin-echo detector. This result can be scaled to a gradient of 5T/m at 10kG.The precession frequency of the recovered nuclear magnetization appearing in the spin-echo signal depends on the NMR sample size, except in the case of res
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onance where the rf frequency of the 180°-pulse coincides with the NMR frequency determined by the average field strength in the sample. We developed a variable frequency spin-echo detector to search the field strength and to eliminate the sample size effect with the support of a Grant-in-Aid for Scientific Research from the Ministry of Education. At this moment we are in the final stage of system tuning. In parallel with detector development, we studied methods for spectral analysis of the spin-echo signal for the field measurement. Applying an improved FFT analysis to the spin-echo signal, we obtained a resolution of 0.45G for the field measurement at 2.35kG, and we confirmed the sample size effect experimentally. This result indicates that we can realize a resolution smaller than 0.1G without serious difficulties.
After completion of detector tuning, we will perform a long term performance test in the gradient field of 〜15G/cm at a KEKB/LER bending magnet. In the final step, we will attempt field measurement of a quadrupole magnet of the KEKB accelerator with 〜10T/m field gradient. Less
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