2000 Fiscal Year Final Research Report Summary
Development of positron remoderator with solid rare-gas
| Project/Area Number |
10680490
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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 |
Nuclear engineering
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| Research Institution | Osaka University |
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Principal Investigator |
NISHIJIMA Shigehiro ISIR Osaka University Associate Professor, 産業科学研究所, 助教授 (00156069)
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| Co-Investigator(Kenkyū-buntansha) |
KIMURA Norio ISIR Osaka University Research Associate, 産業科学研究所, 助手 (80195370)
TAGAWA Seiichi ISIR Osaka University Professor, 産業科学研究所, 教授 (80011203)
HONDA Yoshihide ISIR Osaka University Research Associate, 産業科学研究所, 助手 (40209333)
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| Project Period (FY) |
1998 – 2000
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| Keywords | solid rare gas / positron / remoderator / S-parameter / crystalline / positron lifetime / free volume / molecular dynamics simulation |
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| Research Abstract |
To produce intense slow positron beam, a remoderator assembly using solid rare gas has been developed. We have used argon gas, which was solidified by a refrigerator. To produce solid argon remoderator with high reemission efficiency, the solid has to have little defects where a positron is trapped. By means of the calculation and the experiment, the structure of solid argon was studied, and the most appropriate condition for the remoderator was evaluated.
To evaluate the structure of the solid, the calculation of the positron lifetime was performed. By means of the molecular dynamics simulation the amorphous argon was made and the wave function of positron was calculated. The relationship between positron lifetime and mean free volume was obtained. It is thought that this calculation should be helpful to analyze the structural of the solid argon when the positron lifetime will be measured. S-parameter measurement was performed to evaluate the structure of the solid. As a result of S-parameter measurement, it was found that the thickness of the solid argon can be controlled to the deposition time.
The reemission efficiency of the solid argon which produced the most appropriate condition was measured The reemission efficiency of the solid argon remoderator with highest efficiency was 1.3 times larger than that of tungsten remoderator which had been used popularity.
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