| Project/Area Number |
07554006
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
MASAIKE Akira Kyoto Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (40022587)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Hirohiko The Institute of Physical and Chemical Reserach, Research Assoicate, 研究員 (50249900)
FUNAHASHI Haruhiko Kyoto Univ., Graduate School of Science, Research Assoicate, 大学院・理学研究科, 助手 (00283581)
ENYO Hideto Kyoto Univ., Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (30213606)
TERASHIMA Masahide Kyoto Univ., Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00188674)
HIROTA Noboru Kyoto Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90093301)
石川 潔 京都大学, 大学院・理学研究科, 助手 (00212837)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥18,900,000 (Direct Cost: ¥18,900,000)
Fiscal Year 1997: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1996: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1995: ¥9,200,000 (Direct Cost: ¥9,200,000)
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| Keywords | polarized proton / triplet state / naphthalene / pentacene / dye-laser / solid sffect / relaxation time / 常温陽子偏極 / 偏極標的 / トリプレット状態 / レーザーによる偏極 |
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| Research Abstract |
We have polarized protons in molecular crystals of naphthalene doped with pentacene using a dye laser in 3 KGauss at the temperature higher than 77 Kelvin. In this new method electrons are excited to high singlet states with the laser beam, where the spin-orbit interaction causes the transition from singlet states to intermediate triplet states. The populations of the Zeeman sublevels of the lowest triplet states with Z-components of the total electron spin+1,0, -1 are 12,76 and 12% respectively. During the lifetime of the triplet state (some 20 microsec) microwave irradiation occurs and the external field is swept simultaneously to transfer the population difference of electrons between two Zeeman sublevels to the proton polarization by means of the integrated solid effect. Electrons on the triplet states decay to the ground state, where the proton spin remains polarized for a long time.
We have tried to polarize protons in naphthalene doped with pentacene (0.01 mol%) with a high-power pulsed dye-laser (lambda=590-605nm) and got about 34% polarization at liquid nitrogen temperature. The enhancement factor corresponding to this value is 8*10^4. The relaxation times of protons are about 1,000 and 160 minutes in hte field of 3KG and 7G respectively. The method is applicable to the wide fields of spin physics. Since the target has no heating problem and no serious problem of radiation damage, it can be used for high-intensity beams of hadrons and electrons. Secondly, the target is useful for experiments with very low-momentum charged particles, since the necessary magnetci field to keep the polatization is extremely low.
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