1998 Fiscal Year Final Research Report Summary
Experimental evaluation of the neutron- and gamma-ray doses from the Hiroshima atomic bomb
| Project/Area Number |
08309008
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | HIROSHIMA KOKUSAI GAKUIN UNIVERSITY |
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Principal Investigator |
HASAI Hiromi Faculty of Engineering, HIROSHIMA KOKUSAI GAKUIN UNIVERSITY,Professor, 工学部, 教授 (70034337)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANISHI Takashi Faculty of Science, Kanazawa University, Associate Professor, 理学部, 助教授 (00019499)
SHIBATA Tokushi High Energy Accelerator Research Organization, Professor, 加速器研究機構, 教授 (80028224)
SHIZUMA Kiyoshi Faculty of Engineering, Hiroshima University, Professor, 工学部, 教授 (10127657)
ENDO Satoru Research Institute for Radiation Biology and Medicine, Hiroshima University, Res, 原爆放射能研究所, 助手 (90243609)
HOSHI Masaharu Research Institute for Radiation Biology and Medicine, Hiroshima University, Pro, 原爆放射能研究所, 教授 (50099090)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Atomic bomb / Neutron / Gammaray / Dosimetry / Hiroshima / Neutronactivation |
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| Research Abstract |
The dosimetry system 1986 (DS86) has been used in Radiation Effects Research Foundation and Research Institute for Radiation Biology and Medicine, Hiroshima University. However, we found the discrepancy between the measured data from the atomic-bomb exposed rocks and the calculation based on DS86. Therefore, we have been studied the problem of its contradiction since 1987. The highest discrepancy is seen in the neutron activation data in Hiroshima. For example at 1.5 km, data are higher from 5-10 times than that of calculation. Therefore, we (1) had made re-measurements where the data have large errors or that the data themselves contradicted each other, (2) made benchmark test to verify the calculation and (3) made inter-comparison between US-groups. Based on the obtained new data, we can verify that the data in Hiroshima were correct and that the contradiction among the data themselves in Nagasaki are almost verified not to contradict with DS86. However the long distance data in Hiroshima still have problems. One of the collaborator in this project proposing the concept that the atomic bomb had a crack as if bottom of it was came off and bare fission neutrons leaked from through the cracking space. Thus the contradiction can be explained. This idea was presented at the workshop with US-groups this year and I had impression that they had a feeling that this model can explain the problem. Our proposal is (1) the bottom of the bomb came off and 3cm slit was produced and that fast neutrons leaked through this slit, (2) elevation of neutron emission point about lOOm and (3) increment of the yield about 20%. We would like to see future progress in this field.
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