| Project/Area Number |
01460019
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | Osaka University |
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Principal Investigator |
TAKAHASHI Noriaki Osaka University, College of General Education Professor., 教養部, 教授 (10028152)
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| Co-Investigator(Kenkyū-buntansha) |
BABA Hiroshi Osaka University, Faculty of Science, Professor, 理学部, 教授 (60156536)
ITAHASHI Takahisha Osaka University, Research Center for Nuclear Physics, Associate Professor, 核物理研究センター, 助教授 (20112071)
FUJITA Yoshitaka Osaka University, College of General Education, Research Associate, 教養部, 助手 (60093457)
MIYATAKE Hiroari Osaka University, College of General Education, Research Associate, 教養部, 助手 (50190799)
SHIMODA Tadashi Osaka University, College of General Education, Associate Professor, 教養部, 助教授 (70135656)
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| Project Period (FY) |
1989 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1989: ¥4,200,000 (Direct Cost: ¥4,200,000)
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| Keywords | Superfluid Helium / Impurity Ion / Snowball / Micro-cluster / Radioactive Beam / beta -Ray Detection Method / alpha -Particle Detection Method / Nuclear Moment / マイクロ クラスタ- / ベ-タ放射性核 / 不安定核ビ-ム |
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| Research Abstract |
Impurity ions introduced in liquid helium may behave as singly charl&ed entities with effective mass of 50-100 He atoms, which are referred to as snowballs. A snowball is, therefore, an aggregate, a micro-cluster of helium atoms by means of electrostriction around an impurity core ion admitted in liquid helium. Not only helium ions as first noticed but also any other alien ions do form snowballs. The method used in the study of polarization phenomena in heavy ion reactions enabled us to conceive renewed interests to approach individual snowballs through alpha- and beta-ray countings, which have been developed here.
While the snowball has been thought of a highly paramount solid entity, there are still doubt whether all the existing, evidences do decisively favour the picture of a solid core. The preservation of nuclear polarization in this research provided with an important clue to this issue, enabling us to test the inherent structure of snowballs directly as well as to peripheral problems of the above experiment.
Here, in this report, preservation of nuclear polarization of core ions ^<12>B (T^<1/2> = 20.4 ms, beta-radioacitve) and measurement of lifetime of ^8Li (T^<1/2> = 832 ms, beta- and alpha-radioactive) snowballs have been accomplished. It has been proved that the snowballs are far long-lived as compared to ^<12>B, namely, half-life of snowballs was obtained as 350 ms. This observed long lifetime supports the view that the snowballs constitute a suitable milieu for maintaining nuclear polarization of short-lived core ions throughout their lifetime, and the way is opened investigate nuclear moments of variety of unstable nuclei.
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