| Project/Area Number |
09440099
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | High Energy Accelerator Research Organization |
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Principal Investigator |
WADA Michiharu High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Research Associate, 素粒子原子核研究所, 助手 (50240560)
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| Co-Investigator(Kenkyū-buntansha) |
OHTANI Shunsuke University of Electro-Comm., Professor, レーザーセンター, 教授 (60023735)
KAWAKAMI Hirokane High Energy Accelerator Research Organization, Institute of Particle and Nuclear, 素粒子原子核研究所, 助手 (50013412)
KATAYAMA Ichirou Tokyo University, Dept.of Phisics, Professor, 大学院・理学系研究科, 教授 (30028237)
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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 |
¥14,600,000 (Direct Cost: ¥14,600,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥12,600,000 (Direct Cost: ¥12,600,000)
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| Keywords | Hyerfine anomaly / Be / Laser-microwave spectroscopy / RF-ionguide / RFイオンガイド / ベリリウム-7 / 超微細構造定数 / 超微細構造異常 / 価中性子 |
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| Research Abstract |
This research project aimed at developing an experimental method to perform nuclear laser spectroscopy of unstable Be isotopes. The hyperfine coupling constant A in the atomic hyperfine interaction shows a weak but finite isotope dependence called hyperfine anomaly, the main part of which stems from the finite size of the magnetization distribution in the nucleus (Bohr-Weisskopf effect). This effect affords a unique and interesting probe for valence neutron distribution in a nucleus, particularly in a so-called neutron halo nucleus such as Be-ll.
Various developments for the experimental technique have been carried out using the stable isotope of Be-9 trapped in a linear RE trap placed at a weak magnetic field. High sensitive detection of microwave-resonance was demonstrated using continuous irradiation method where laser and microwave radiations were continuously applied. A high S/N resonance signal was observed with in a few seconds of measurement. A high precision measurement was also tested using a pulsed method. By repeating the short cycle (a few ins) of alternative irradiation of laser and microwave radiation, reasonably high accuracy of 2*1O-7 was obtained.
Trial experiments for investigating the first unstable isotope of Be-7 have been carried out, however, no fluorescence signal was observed so far. The difficulty is considered to be due to the luck of knowledge in the resonant wave-length and to the fact that the number of Be-7 ions in the trap are critical. Various kind of improvements in the theoretical calculation of the specific isotope shift as well as in the experimental technique to increase the density of Be-7 ions in the trap are under progress.
For shorter lifetime isotopes, such as Be-ll, an on-line trapping method for energetic beams from a fragment isotope separator is also under development using a newly proposed RE-ionguide technique.
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