2002 Fiscal Year Final Research Report Summary
Differential cross section measurement of first neutrons for the evaluation of Hiroshima and Nagasaki atomic-bomb dosimetry
| Project/Area Number |
12480140
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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 |
Nuclear engineering
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SHIZUMA Kiyoshi Hiroshima University, Graduate school of Engineering, Professor, 大学院・工学研究科, 教授 (10127657)
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| Co-Investigator(Kenkyū-buntansha) |
KOJIMA Yasuaki Hiroshima University, Graduate schoool of Engineering, Research Associate, 大学院・工学研究科, 助手 (80314730)
ENDO Satoru Hiroshima University, Graduate schoool of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (90243609)
HOSHI Masaharu Hiroshima University, Research Institute for Radiation Biology and Medicine, Professor, 原爆放射線医科学研究所, 教授 (50099090)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Neutron transport / Elastic cross section / Neutron / MCNP / Neutron dosimetry / A-bomb / Residual activity / DS86 |
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| Research Abstract |
The risk of radiation is mainly based on the radiation doses for Atomic-bomb survivors of Hiroshima and Nagasaki. Reevaluation of A-bomb doses of Hiroshima and Nagasaki started around 1980 both in US and Japan. Afterward, residual activity data of ^<152>Eu, ^<60>Co,^< 36>Cl and ^<63>Ni were gradually accumulated, and a systematic discrepancy has been revealed. A possible explanation of the discrepancy is neutron transport calculation in air, especially the validity of the cross section of nitrogen and oxygen. The experimental values of previous works are lacking at forward directions. The purpose of this work is to determine the differential cross sections of nitrogen and oxygen in detail.
Summary of present work is as follows.
(1) According to the neutron beam collimation experiment with 780 keV neutrons, collimator thickness of poliethylen block is necessary more than 20 cm. This result is in agreement with the Monte Carlo simulation results.
(2) To determine the differential cross sections of nitrogen and oxygen, Nitrogen oxide and Si oxide should be utilized and background should be subtracted to get enough counting statistics.
(3) According to the neutron scattering experiment with thin plastic scintillator as a target, thermal neutron scattering and scattered neutrons from carbon were observed. This result indicates the reduction of thermal neutron scattering is necessary to determine the cross section in the forward direction.
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Research Products
(10 results)
