1996 Fiscal Year Final Research Report Summary
EXPLORATORY STUDIES OF ANOMALOUSLY LONG-LIVED HADRONIC ATOMS
| Project/Area Number |
04101002
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Research Institution | INSTITUTE FOR NUCLEAR STUDY,UNIVERSITY OF TOKYO |
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Principal Investigator |
YAMAZAKI Toshimitsu INSTITUTE FOR NUCLEAR STUDY,UNIVERSITY OF TOKYO,PROFESSOR EMERITUS, 原子核研究所, 名誉教授 (80011500)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Yasuo RESEARCH CENTER FOR NUCLEAR SCIENCE & TECH,UNIVERSITY OF TOKYO,ASSOC.PROF., 原子力研究総合研究センター, 助教授 (40011150)
MORITA Norio INSTITUTE FOR MOLECULAR SCIENCE,UNIVERSITY OF TOKYO ASSOC.PROF., 分子科学研究所, 助教授 (30134654)
HAYANO Ryugo FACULTY OF SCIENCE,UNIVERSITY OF TOKYO,PROF., 大学院・理学系研究科, 教授 (30126148)
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| Project Period (FY) |
1992 – 1996
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| Keywords | ANTIPROTONS / LASER SPECTROSCOPY / HELIUM ATOM / PIONS / NUCLEUS |
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| Research Abstract |
(1) Extensitive experimental programs on long-lived antiprotons in helium media have been carried out by using the antiproton beam from LEAR at CERN.First, delayd annihilation time spectra of antiprotons were measured precisely. Not only in liquid phase but also in gas and solid phase 3% of stopped antiprotons were observed to have lifetimes about 3-4 microseconds. Secondly, laser resonance spectroscopy was developed to clarify the mechanism of this anomalous longevity. The method proposed was to induce stimulated transitions between a metastable state and a short-lived state using an intense pulsed laser and to detect the transition as a sharp spike in delayd annihilation time spectra. Successful observations of many resonance transitions came out. The resonance wavelengths observed agree with theoretical expectations, which established that the metastability arises from long-lived states of large angular momenta. The precise spectroscopy including the observation of hyperfine structure has provided important data on the particle-antiparticle symmetry and few-body theories. Various effects of surrounding helium and foregn atoms and molecules on the metastable atoms have also been found and studied by laser spectroscopy.
(2) Deeply-bound pionic states in 207Pb have been discocovered at GSI using the 208Pb (d, 3He) reaction at 600 MeV.
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