| Project/Area Number |
08504002
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | University of Tokyo |
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Principal Investigator |
TANABE Tetsumi University of Tokyo School of Science, Professor, 大学院・理学系研究科, 教授 (20013394)
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| Co-Investigator(Kenkyū-buntansha) |
NODA Kouji National Institute of Radiological Sciences, Division of Accelerator Physics and, 医用重粒子物理工学研究部, 主任研究官 (80228329)
CHIDA Katsuhisa High Energy Acceleraor Reseach Organization, Research Associate, 助手 (90013391)
KATAYAMA Ichiro University of Tokyo School of Science, Professor, 大学院・理学系研究科, 教授 (30028237)
菅井 勲 東京大学, 原子核研究所, 助手 (80150291)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥46,400,000 (Direct Cost: ¥46,400,000)
Fiscal Year 1997: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1996: ¥41,900,000 (Direct Cost: ¥41,900,000)
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| Keywords | Accelerator / Electron Cooling / Superconducting Magnet / Atomic Physics / Atomic Collisions / Dissociative Recombination |
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| Research Abstract |
An electron cooling method has widely been used in the atomic physics research as well as accelerator technology. The cooling time and the final accuracy in experiments are determined by the electron temperature. The electron beam has initially an energy width (or temperature) of about 100 meV,since electrons are emitted from a hot cathode. However, electron temperature can be reduced to a level less than the cathode temperature by expanding the electron beam adiabatically in a gradually decreasing solenoid field. This method is called 'adiabatic expansion method' and the electron temperature decreases in inverse proportion to an expansion factor. Based on this principle, we modified the existing electron system to the adiabatic expansion type. In the fiscal 1996, we designed and constructed an superconducting electron cooler with a magnetic field of 3.5 T and realized an expansion factor of 100 resulting in an electron temperature of 1 meV for the first time in the world. The supercon
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ducting magnet is liquid-helium free, which realized a compact design and a simple operation. The cooler opened the way to the super-fast beam cooling and extremely high-accuracy experiments. In the fiscal 1996-1997, highly accurate atomic collision experiments have been performed with this cooler. Dissociative recombination (DR) of molecular ions is one of the important processes in the upper atmosphere and the outer space. The DR of HeH^+ isotopes were studied with the extremely low-temperature electron beam of the order of 1 meV produced by the superconducting electron cooler at the storage ring TARN II.The DR spectra show a fine new structure and a clearisotope dependence in the low energy region. Those features are well reproduced by the theoretical calculations based on a multichannel quantum-defect theory. According to the theory, the newly observed structure is an evidence of a new indirect mechanism. These results on the cooler and the physics experiments have been presented at the domestic conferences in Osaka and at Kobe, and the foreign conferences in Vancouver, Vienna and Heidelberg. We also started the feasibility study of atomic collision experiments with the new cooler on many other ions. Less
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