| Project/Area Number |
01460020
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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, Faculty of General Education |
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Principal Investigator |
SHIMODA Tadashi (1990) Osaka University Faculty of General Education Associate Professor, 教養部, 助教授 (70135656)
森信 俊平 (1989) 大阪大学, 核物理研究センター, 助教授 (50016078)
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| Co-Investigator(Kenkyū-buntansha) |
MORINOBU Shunpei Kyushu University Faculty of Science Professor, 理学部, 教授 (50016078)
MIYATAKE Hiroari Osaka University Faculty of General Education Research Associate, 教養部, 助手 (50190799)
下田 正 大阪大学, 教養部, 助手 (70135656)
片山 一郎 大阪大学, 核物理研究センター, 助教授 (30028237)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1989: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Keywords | Nuclear reaction recoil / Mass separation / Beta transition probability / Proton rich nuclei / M1 giant resonance / M1巨大共鳴 |
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| Research Abstract |
We have previously succeeded in commissioning the recoil separator CARP at the Research Center for Nuclear Physics, Osaka University. This device allows us to mass-separate nuclear reaction products and transport them into the detecting position in the form of a secondary beam. Considering the advantage of the use of the separator, the objective of the present investigation was set at the accurate measurement of the Gamow-Teller (GT) beta-transition rates of the proton rich T_z = -3/2 and -2 nuclei in the sd-shell. This was to promote deeper understanding of the quenching mechanism of the giant M1 resonance, by facilitating the detailed comparison of the GT-strength between the theory and experiment for a wide range of nuclei far off the beta-stability line.
In the early stage of the investigation, an emphasis was placed on the achievement of a large solid angle of the recoil separator for the reaction products and on the construction of a detector system which is highly sensitive to the beta-rays and associated radiations with the decay of the products but insensitive to the external background radiations. Following these developments of the apparatus, a gain of a factor of no smaller than 20 over the previous experimental set-up was found achieved in the overall collection efficiency of the data.
Taking account of the relatively large production cross sections of the T_z = -3/2 nuclei, the first experiment was determined to be carried out on ^<13>O, ^<21>Mg, ^<25>Si, ^<21>S, ^<37>Ca and ^<41>Ti. We have successfully completed the measurements for all these T_z = -3/2 nuclei by the time of preparing this report. The analysis of the data has been completed for ^<25>Si and the quenching factor of the GT-strength was determined. An unexpectedly large concentration of the GT-strength was found in the isobaric analog state of ^<25>Si in ^<25>Al. For the other nuclei, the data analysis is under way. The experiments for the T_z = -2 nuclei are about to start.
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