| Project/Area Number |
09680483
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
エネルギー学一般・原子力学
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| Research Institution | The University of Tokushima |
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Principal Investigator |
KOORI Norihiko Univ of Tokushima, Fac.Integrated Arts & Sci.Prof., 総合科学部, 教授 (20038053)
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| Co-Investigator(Kenkyū-buntansha) |
FUSHIMI Ken-ichi Univ of Tokushima, Fac.Integrated Arts & Sci.Lect., 総合科学部, 講師 (90274191)
NAKAYAMA Shintaro Univ of Tokushima, Fac.Integrated Arts & Sci.Prof., 総合科学部, 教授 (70116846)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | scintillator / low background / GSO / scintillation mechanism / environmental neutron / Pulse shape analysis / 2重β崩壊 |
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| Research Abstract |
In this research, very low backgrounds are intended to be realized for measurements of environmental gamma-rays and neutrons with GSO (Gd_2SiO_5 : Ce) scintillators. It may be possible if events from contaminated radioactive elements in GSO scintillators are discriminated. Followings are the results from the present research.
(1) Low background measurement with a GSO scintillator : The very long half-life of Gd-152 and knowledge on the Onubetabeta decay from Gd-160 were obtained under very low background conditions. From the measurements contamination of these elements and U- and Th-series elements were estimated.
(2) Neutron detection with a GSO scintillator : The GSO scintillator response were observed for thermal neutrons. Gamma-rays of 79.5 keV from Gd-158 resulted by the thermal neutron capture were confirmed with a low intensity neutron source, and then a high detection efficiency of 14% was obtained for a 0.9" phi * 1" GSO crystal. Applications will be planed to measurement of very low flux of environmental neutrons will be possible.
(3) Pulse shape of scintillation from a GSO scintillator : In order to discriminate alpha-rays from the contaminated elements in GSO scintillators for very low background condition, scintillation pulse shapes were measured with a high speed digital oscilloscope. A pulse shape analyzing system were developed for this purpose, and measured the decay times of scintillation from GSO crystals of different Ce concentrations. No large difference in the decay times of scintillations for alpha-rays and gamma-rays. Further measurements for dependence to applied temperature will be needed.
The present research provides the knowledge about very low background condition with GSO scintillators.
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