| Project/Area Number |
07555188
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 試験 |
|---|
| Research Field |
Physical properties of metals
|
|---|
| Research Institution | Osaka University (1996)
Kyoto University (1995) |
|---|
Principal Investigator |
SHIRAI Yasuharu Department of Materials Science and Engineering, Osaka University, Professor, 工学部, 教授 (20154354)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NISHITANI Shigeto Department of Materials Science and Engineering, Kyoto University, Research Asso, 工学研究科, 助手 (50192688)
ARAKI Hideki Department of Materials Science and Engineering, Osaka University, Research Asso, 工学部, 助手 (20202749)
|
|---|
| Project Period (FY) |
1995 – 1996
|
| Project Status |
Completed (Fiscal Year 1996)
|
| Budget Amount *help |
¥8,700,000 (Direct Cost: ¥8,700,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥8,000,000 (Direct Cost: ¥8,000,000)
|
|---|
| Keywords | positron beam / positron lifetime / characterization of materials / lattice defect / 陽電子消滅 / 熱平衡空孔 |
|---|
| Research Abstract |
In order to achieve in-situ studies of condensed matter under extremeconditions, new beta^+-gamma conicidence lifetime spectrometer with the coincidence of energy-selected positron and the annihilation photon has been constructed. The whole apparatus is desk-top and low cost, since it does not need any accelerators but a small sealed positron-source and a pair of magnetic lenses. Specimens can be exposed to any extreme surrounding conditions without the risk of contamination by radioactive materials, since the specimen part is independent and well-separated from the sealed positron-source. In order to overcome the inevitable deterioration of time resolution due to the spread of TOF (time of flight) of positrons emitted from radioisotopes, positrons in a certain energy band are selected using magnetic field. The total efficiency (more than 10^<-3> of positrons from the source can be focused on a specimen) is much superior to that expected for the case of re-acceleration of moderated positrons. The time resolution of the whole system with a 10mCi^<22> Na positron source is about 385ps (FWHM) as yet, which is worse than that of the conventional gamma-gamma coincidence method (around 200ps FWHM typically) but bears comparison with former beta^+-gamma coincidence lifetime spectrometers using close geometry between the positron source and a specimen.
|
