Study of nuclear deformation along the neutron drip line via proton inelastic scattering

通过质子非弹性散射研究沿中子滴线的核变形

• 批准号: 15540257
• 负责人: NAKAMURA Takashi
• 金额: $ 2.37万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540257/
• 关键词: Radioactive Beam; Inelastic scattering; Drip-line nuclei; Nuclear Deformation; 中性子ハロー; 魔法数の破れ; 中性子ハロー核; 殻構造の変化

We have studied inelastic scatterings of drip-line nuclei, ^<11>Be, ^<14>Be, ^<15>B, ^<17>B, ^<18>C and ^<19>C on a proton target as well as on a carbon target. In this study we aimed at exciting primarily the first excited state, which has information of deformation of these nuclei. The deformation of such nuclei have attracted much attention since the extreme neutron to proton ratio may cause the change of nuclear shell structures represented by the magicity loss, or even the decoupling effect on the valence neutrons.In this study, not only the bound excited states which can be measured by in-beam gamma spectroscopy, but also the unbound states which can be reached by the invariant mass spectroscopy. For the latter, we have developed a new drift chamber which can measure angles of an ejectile with very high accuracy (less than 0.1 deg). We have also developed a new scheme of analyzing two-neutron events, which was essential to specify the excited state in two-neutron halo nucleus ^<1 … More 4>Be.A series of experiments were performed at RIKEN accelerator Research facility, where the intense radioactive beam is available. The drip-line nuclei were produced by the projectile, fragmentation and purified through the fragment separator RIPS. The excitation energy was obtained either by the method mentioned above.We have observed for the first time the 1^<st> excited state of ^<17>B in the bound excited state and that of ^<14>Be just above the particle decay threshold at Ex=1.56 MeV. The cross sections for producing the first excited states in ^<17>B and ^<15>B suggest that the effective charges for these nuclei are extremely small compared to the conventional value. This may be related to the decoupling effect which was found for the neighboring nucleus ^<16>C. As for ^<14>Be, the first excited states located at 1.56 MeV, lower than that of ^<12>Be at 2.1 MeV. This suggests that the ^<14>Be has even more melted shell structure than the case of 12Be, which was recently found as a magicity-lost nucleus. However, the deformation parameter extracted for ^<14>Be was smaller than that of 12Be. This may be understood as a restoration of shell stability. This interesting findings are to be further studied with theories including the shell melting or cluster nature of these nuclei. For other nuclei, we have also observed a new state as well.We are now planning to use the different probe of alpha target, an ideal isoscalar probe. This may clarify the shape difference between the neutron distribution and the proton distribution. For the very extreme neutron/proton ratios, we expect more decoupled situation where neutrons moves independently of protons. Studies of such very exotic excitation is important to understand the behavior of very neutron rich nuclei. Less

我们研究了滴水细胞核的非弹性散射， ^<11> be， ^<14> be， ^<17> b， ^<17>以及在这项研究中。激发态的e。不变性的伽马光谱法。在Tw-Neutron Halo nucleus ^<1中的状态…更多4> BE。在rikcelerator的易晶中进行了一系列实验，在该方法中，强烈的放射光束是弹丸，通过方法是通过方法。 ^<17> bin的1 ^<st> ^<14>的激发态在ex = 1.56 meV时为粒子衰减。 > B ^<15> B表明，与召集值相比，核的有效电荷非常小。 2.1 MEV。 s壳融化或其他核的核心，我们也观察到了新的状态。我们期望更多的脱钩质子对质子较少

项目成果

Y.Yanagisawa,..., T.Nakamura et al.: "The first excited state of 30Ne studied by proton inelastic scattering in reverse kinematics"Physics Letters B. 566. 84-89 (2003)

Y.Yanagisawa,..., T.Nakamura 等人：“通过反向运动学中的质子非弹性散射研究 30Ne 的第一激发态”物理快报 B. 566. 84-89 (2003)

Coulomb and nuclear breakup of halo nuclei

• DOI: 10.1016/j.nuclphysa.2004.01.057
• 发表时间: 2004-04
• 期刊: Nuclear Physics
• 作者: Takashi Nakamura

Sensitivity of r-process Nucleosynthesis to Light Element Nuclear Reactions

r 过程核合成对轻元素核反应的敏感性

• 发表时间: 2005
• 期刊: Astrophys.J 634
• 作者: T.Sasaqui;T.Kajino;G.J.Mathews;K.Otsuki;T.Nakamura
• 通讯作者: T.Nakamura

In-beam γ-ray spectroscopy of the neutron-rich boron isotopes ^<15,17>B via inelastic scattering on ^<12>C

通过 ^<12>C 上的非弹性散射对富中子硼同位素 ^<15,17>B 进行束内 γ 射线光谱分析

• 发表时间: 2005
• 期刊: Physical Review C (In press)
• 作者: Y.Kondo;T.Nakamura et al.
• 通讯作者: T.Nakamura et al.

Coulomb and nuclear breakup of a halo nucleus 11Be

• DOI: 10.1103/physrevc.70.054606
• 发表时间: 2004-09
• 期刊: Physical Review C
• 影响因子: 3.1
• 作者: N. Fukuda;T. Nakamura;N. Aoi;N. Imai;M. Ishihara;T. Kobayashi;H. Iwasaki;T. Kubo;A. Mengoni;M. Notani;H. Otsu;H. Sakurai;S. Shimoura;T. Teranishi;Y. Watanabe;K. Yoneda