1991 Fiscal Year Final Research Report Summary
Study of Giant resonances in Hot Nuclei produced in Heavy Ion Fusion Reactions
| Project/Area Number |
02640219
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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 | Tokyo Institute of Technology |
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Principal Investigator |
KASAGI Jirohta Tokyo Inst. of Tech., Ass. Professor, 理学部, 助教授 (10016181)
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| Co-Investigator(Kenkyū-buntansha) |
MURAKAMI Takeshi Tokyo Inst. of Tech, Research Ass., 理学部, 助手 (20166250)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Giant Resonance / Hot Nuclei / Heavy Ion Reaction / Fusion Reaction / High Energy gamma rays / Level Density / Limiting Temperature / Statistical Model |
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| Research Abstract |
1. We have studied properties of hot nuclei by using ^<40>Ar+Ni, ^<92>Mo, and ^<122>Sn reactions with E/A=21 and 26 MeV by using the RIKEN Ring Cyclotron. Fusion reaction process was selected to study level densities and giant dipole resonances in hot nuclei. It was found that neutron energy spectra measured in coincidence with fusion residues were reproduced with the level density parameter a=A/(9<plus-minus>1). However, yields of the GDR decay gamma rays do not increase above E_x-250 MeV. The limiting temperature for the GDR gamma -ray decay were deduced as T_c-17A^<-1/3> for 80 < A < 150. It is highly desirable to continue the systematic study in order to answer the question whether the collective motion of the nucleus disappears at the high temperature or the hot nucleus is cooled down by particle evaporations before it emitts gamma rays.
2. In order to investigate the dependence of giant dipole resonances on the excitation energy and the angular momentum, high energy gamma rays were measured in ^<100>Mo+^<32>S reaction with E=150, 180 and 210 MeV using the tandem accelerator at JAERI. The result shows that the GDR width depends strongly on the thermal excitation energy for E_x > 100 MeV and an empirical formula GAMMA =4.5+0.035E_x+1.6x10^<-8>E_x^4 obtained in the previous work at RIKEN can explain the data very well.
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[Publications] J. Kasagi, K. Yoshida, H. Hama, M. Sakurai, M. Kodama, K. Furutaka, K. Ieki, W. Galster, T. Kubo, M. Ishihara and A. Galonsky: ""Gamma-Ray and Neutron Emission from Hot Nuclei"" Proc. of the 2nd IN2P3-Riken Symposium on Heavy Ion Collisions, Obernai, France. World Scientific Pub. 304-313 (1990)
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「研究成果報告書概要(欧文)」より
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[Publications] J. Kasagi, K. Furutaka, T. Murakami, A. Yajima, M. Ohshima, S. Niiya, H. Tominaga, K. Yoshida, H. Hama, K. Ieki, W. Galster, T. Kubo, M. Ishihara and A. Galonsky: ""Excitation Energy and Spin Dependence of the Giant Dipole Resonance at Finite Temperature"" Nucl. Phys.(1992)
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「研究成果報告書概要(欧文)」より
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[Publications] K. Yoshida, J. Kasagi, H. Hama, M. Sakurai, M. Kodama, K. Furutaka, K. Ieki, W. Galster, T. Kubo, M. Ishihara and A. Galonsky: ""Neutron Emission for the Fusion of ^<40>Ar+Ni, ^<92>Mo, ^<122>Sn Reactions at E/A=26 MeV"" Phys. Rev. C.
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