Study of structure of unstable nuclei with the new method of beta-delayed spectroscopy

β延迟光谱新方法研究不稳定核结构

基本信息

批准号：
17540256
负责人：
SHIMODA Tadashi
金额：
$ 2.24万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17540256/
关键词：
beta decay spin polarization beta-delayed decay states in the daughter nucleus spin-parity neutron-rich nuclei magic number 娘核の準位ベータ遅発中性子崩壊中性子散乱

项目摘要

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.

已成功应用了一种新方法，用于研究11BE的外来结构。本方法的基本特征是使用自旋极化的放射性核核。 beta-decay不对称使我们能够分配Beta-Decay女儿状态的旋转率。在11BE中，已经针对七个州进行了稳定的旋转率分配，并且还确定了其详细的衰减路径。从这些证据中可以发现，各种类型的群集状态CO存在于11BE中。在过去的两年中，我们专注于低能中子数据分析。在11BE→10BE + N的β延迟中子衰减中，必须至少有两个与非常低的能量中子发射有关的衰减路径。我们使用五个6Li掺杂的玻璃闪烁体来检测中子的能量少于200 keV。为了在检测之前通过实验设备的材料评估中子散射的影响，已经进行了基于中子传输代码MCNP的蒙特卡洛模拟。通过模拟中子响应函数的帮助，已经仔细地分析了实验中子光谱。成功分配了具有16 keV和72 keV的动能的两个中子峰，并首次确定了两个中子衰减路径和强度。它计划将目前确定的方法应用于非常中子富含中子的MG同位素的结构研究。可行性已详细研究。在加拿大Triumf的实验提案已经完成。实验评估委员会建议将该提案作为具有高优先级的实验。实验将于2007年进行。