2006 Fiscal Year Final Research Report Summary
Study of structure of unstable nuclei with the new method of beta-delayed spectroscopy
| Project/Area Number |
17540256
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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 |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Osaka University |
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Principal Investigator |
SHIMODA Tadashi Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (70135656)
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| Co-Investigator(Kenkyū-buntansha) |
ATSUKO Odahara Osaka University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (30264013)
HIROARI Miyatake High energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Professor, 素粒子原子核研究所, 教授 (50190799)
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| Project Period (FY) |
2005 – 2006
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| Keywords | beta decay / spin polarization / beta-delayed decay / states in the daughter nucleus / spin-parity / neutron-rich nuclei / magic number |
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| Research Abstract |
A new method in beta-delayed decay spectroscopy has been successfully applied to investigate the exotic structure of 11Be. The essential feature of the present method is a use of spin-polarized radioactive nucleus. The beta-decay asymmetry enables us to assign the spin-parity of the beta-decay daughter state. Firm spin-parity assignments have been made for seven states in 11Be, and their detailed decay paths have also been determined. From these evidences it was found that various types of cluster states co exist in 11Be.
In the last two years we have focused on the low energy neutron data analysis. In the beta-delayed neutron decay of 11Be →10Be + n there must be at least two decay paths associated with very low energy neutron emission. We used five 6Li-doped glass scintillators to detect the neutrons with energies of less than 200 keV. In order to assess the effects of the neutron scattering, prior to the detection, by material of the experimental apparatus, Monte Carlo simulations based on the neutron transport code MCNP have been performed. The experimental neutron spectra have been carefully analyzed by the help of the simulated neutron response function. Two neutron peaks with the kinetic energies of 16 keV and 72 keV were successfully assigned and the two neutron decay paths and intensities have been determined for the first time.
It was planned to apply the presently established method to the structure studies of the very neutron-rich Mg isotopes. The feasibility has been investigated in detail. A proposal for the experiment at TRIUMF, Canada has been finished. The proposal was recommended as the experiment with high priority by the experiment evaluation committee. The experiment will be performed in 2007.
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Research Products
(4 results)
