| Project/Area Number |
04455019
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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 |
広領域
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| Research Institution | Grant-in-Aid for Scientific Research (B) |
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Principal Investigator |
HASAI Hiromi Hiroshima Univ.Engineering, Professor, 工学部, 教授 (70034337)
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| Co-Investigator(Kenkyū-buntansha) |
SHIZUMA Kiyoshi Hiroshima Univ.Engineering, Associate Professor, 工学部, 助教授 (10127657)
IWATANI Kazuo Hiroshima Univ.Engineering, Associate Professor, 工学部, 助教授 (20034374)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1992: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Keywords | Atomic Bomb / Neutron dose / Europium 152 / Cobalt 60 / residual activity / Depth profile / low-background / Ge detector |
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| Research Abstract |
The specific activity ^<152>Eu/Eu was measured for 80 samples collected within 1500 m from the Hiroshima hypocenter. The residual activity ^<60>Co was also measured for irons and rocks exposed to the A-bomb neutrons. The results are as follows.
1.The directional distribution of emitted neutrons were investigated through the Eu activation. It was found that the activity yield in the direction of WSW decreased rapidly as the function of the distance compered to other directiond. This indicates that the neutron energy was low in this dirction.
2.It was shown that the measured ^<152>Eu and ^<60>Co activities were systematically lower than the calculation near the hypocenter and vice versa at long distances beyond 1000 m. These results are consistent with recent measurement of ^<36>Cl by means of accelerator mass spectroscopy.
3.Depth distribution of ^<152>Eu in stones are similar at distance 100 m (Motoyasu bridge)and at 500 m (Shirakami Shrine).
These results indicate that systematic errors exist in the DS86 neutrons concerning to the source-term spectrum, neutron transport calculation in air, and/or activation measurement.
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