1987 Fiscal Year Final Research Report Summary
Precision Measurement of the <beta>+ Decay Strength of Short-Lived Nuclei Using On-Line Mass Separation
| Project/Area Number |
61460012
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
FUJIOKA Manabu Cyclotron and Radioisotope Center, Tohoku University, サイクロトロン・ラジオアイソトープセンター, 助手 (70016111)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAI Yasuki Department of Applied Physics, Tokyo Institute of Technology, 理学部応用物理学科, 助教授 (80028240)
SHINOZUKA Tsutomu Cyclotron and Radilisotope Center, Tohoku University, サイクロトロン・ラジオアイソトープセンター, 助手 (10134066)
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| Project Period (FY) |
1986 – 1987
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| Keywords | ultra-low background / <gamma>-ray detector / <beta>^+ branching / barium fluoride detector / detection of annihilation radiation / mirror <beta>-decay / Gamow-Teller matrix element / quenching / tape transport / on-line mass separation / ion guide / ^<54>Cu |
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| Research Abstract |
The present project aims at construction of an ultra-low-background <gamma>-ray detector system, with which to measure weak <gamma>-ray branchings of <beta>-decays of short-lived nuclei for deriving precise values of <beta>-decay matrix elements.
In the 1st fiscal year the <gamma>-ray detector system based on gating a Ge detector by a plastic <beta>^+ detector and a BaF_2 system consisting of eight crystals to register two annihilation radiations. The performance of the detector system was tested using a ^<22>Na and other standard sources, showing a background suppression factor <greater than or similar> 10^<-4>.
In the 2nd fiscal year the detector system was installed into a tape-transport system connected to an IGISOL (Ion-Guide Isotope Separator On-Line), and the maximum velocity of tape transport was improved both in hardware and software by a factor of <greater than or similar> 1.6. An on-line experiment was made for the decay of ^<57>Cu, a mirror nucleus of p_<3/2-> shell region, and the 1111.6 keV <gamma>-ray was detected for the first time for mass- separated ^<57>Cu (T_<1/2> = 0.200 s).
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