1992 Fiscal Year Final Research Report Summary
Structure of light neutron-rich instable nuclei and fragmentation reactions of intermediate energy heavy-ions
| Project/Area Number |
03640265
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | Niigata University |
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Principal Investigator |
SUZUKI Yasuyuki Niigata Univ.Faculty of Science.Professor, 理学部, 教授 (70018670)
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| Co-Investigator(Kenkyū-buntansha) |
YABANA Kazuhiro Niigata Univ.Faculty of Science.Assistant, 理学部, 助手 (70192789)
IKEDA Kiyomi Niigata Univ.Faculty of Science.Professor, 理学部, 教授 (40011548)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Neutron-rich nuclei / ^<11>Li / ^6He / Soft dipole mode / Eikonal approximation / Interaction cross sections / Fragmentation reactions / Optical potential |
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| Research Abstract |
The structure of ^<11>Li and He isotopes was studied in a cluster orbital shell model which takes into account loose coupling of the excess neutrons. A spatially extended density distribution chracteristic of halo structure was obtained for ^<11>Li. An importance of di-neutron type cluster configuration was emphasized as a binding mechanism of ^<11>Li. The same approach was extended to examine the dipole strength of the neutron-rich nuclei. The strength predicted at low excitation energy is related to the Coulomb dissociation cross section and was consistent with the experimentally extracted values.
A powerful and simple reaction theory was developed to analyze the fragmentation reaction cross sections and the momentum distribution of the fragments. In this theory the eikonal and adiabatic approximations were used in advantage and the validity of their approximations were tested satisfactorily. The theory was applied to predict the interaction cross section, the two-neutron removal cross section, and the elastic scattering cross section for ^<11>Li-^<12>C system. One important consequence of the analysis was the finding of significant effect of the breakup of the neutron-rich nuclei, which is due to the weak binding of the neutrons. The importance of the breakup effect led to significant modification of the optical potential of ^<11>Li. A new formula was derived which relates various fragmentation cross sections and its validity was confirmed experimentally.
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