| Project/Area Number |
12640397
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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 |
物理学一般
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| Research Institution | Tokyo University of Science, Yamaguchi |
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Principal Investigator |
SHIMIZU Tadao Tokyo University of Science, Yamaguchi Department of Electronics and Information Science, Professor, 基礎工学部, 教授 (90011668)
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| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Taro Himeji Institute of Technology Department of Material Science, Research Associate, 理学部, 助手 (80289305)
立川 真樹 明治大学, 理工学部, 助教授 (60201612)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2001: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | atomic physics / charge transfer collision / ion trap / laser cooling / レーザー冷却 / 衝突散乱断面積 / 電荷移動 / rfイオントラップ / 衝突散乱断面図 / atomic physics / collisional cross section / charge transfer / ion trap / laser cooling / frequency standards |
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| Research Abstract |
The charge transfer process between a laser cooled magnesium ion and a thermal barium atom is successfully observed in a radio frequency ion trap in extremely low energy regime. The merit of ion trap experiment is that the generated ion is also trapped and very high sensitivity is achieved. The production of barium ion is confirmed by observing the laser-induced fluorescence from the ion.
The cross section is estimated to be 10^<-4> nm^2. This well agrees with the value calculated from a theory in the reference (D. Rapp and W.E.Francis, J. Chem. Phys. 37, 2631(1962)).
The charge transfer process allows us to achieve sympathetic cooling of various ions. The magnesium ion is easily cooled by a single laser, because its energy level structure is simple. The charge and "cold temperature" of magnesium ion are transferred to guest ions through collisions. We observed the temperature of sympathetically cooled barium ion of 500K, which is much smaller than that of the ion cooled by Helium buffer gas (4000K). We have calculated the limiting temperatures achieved by the sympathetic cooling as functions of ion temperatures and ion masses. The experimental confirmation of our theoretical model is achieved in a pair of magnesium and barium ions. The theory predicts that when the temperature of host ion is low the heavier guest ions are cooled more efficiently, while the guest ion temperature increases rapidly with increasing mass in higher temperature region. The resonant oscillation modes of sympathetically cooled ions in a radio frequency trap are also investigated through charge transfer process in the trap. Tow types of collective oscillation are observed. The frequency of oscillation can be calculated by a theoretical model, which agrees well with the observation. Irrelevant ions can be removed from the trap by applying an rf-voltage resonant to the proper frequency of the ions.
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