Explosive Nucleosynthesis with Unstable Nuclei - Complementary Studies Using Low- and Intermediate-Energy Unstable Nuclear Beams -

不稳定核的爆炸性核合成 - 使用低能和中能不稳定核束的补充研究 -

• 批准号: 06044205
• 负责人: MOTOBAYASHI Tohru
• 金额: $ 6.66万
• 依托单位: Rikkyo University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044205/
• 关键词: Nuclear astrophysics; Coulomb dissociation; (p, gamma) reaction; Unstable nuclear beam; Solar neutrino; CNO cycle; Hot pp mode; Astrophysical S-factor; 天体核物理; 放射捕獲反応; ガンマ線測定器系

Using beams of unstable nuclei provided by RIKEN Ring Cyclotron with intermediate energies and by Cyclotron complex of Louvain la Neuve with low energies, explosive nuclear burning processes have been studied experimentally. The Coulomb dissociation method was employed at RIKEN for an extensive study of the process ^<208>Pb(^8B,^7Be, p)^<208>Pb, which simulate the ^7Be(p, gamma)^8B reaction, a key process for the solar neutrino problem. Our results suggest very small E2 component, which has been estimated theoretically to cause a serious problem for ^8B Coulomb dissociation results. A new determination of S_<17> will be achieved by the second experiment. We also performed an experiment of ^<12>N dissociation related to the hot pp mode burning process.A direct measurement of the reaction ^<19>Ne(p, gamma)^<20>Na was performed at Louvain la Neuve. This reaction was regarded as a key of mass flow from CNO to NeNa region. The experimental could only give an upper limit of the cross section, which is already much smaller than predictions. Another direct measurement was performed for the ^<13>N(p, gamma)^<14>O reaction, a key to ignite hot CNO cycle from the regular CNO cycle. This experiment was aimed at providing a fair and precise comparison between the Coulomb dissociation and direct capture methods by improving the accuracy of data, because both methods were once applied for the ^<13>N(p, gamma)^<14>O and the results agreed with each other within errors. A gamma-ray detection setup with a high efficiency was build at Rikkyo and brought to Louvain la Neuve to measure 5.17 MeV gamma-rays from the radiative capture reaction induced by radioactive ^<13>N beams with an hydrogen target. Analysis is in progress.

利用RIKEN环形回旋加速器提供的中能不稳定核束流和鲁汶中子回旋加速器提供的低能不稳定核束流，对爆炸核燃烧过程进行了实验研究。理化学研究所采用库仑离解方法对^<208>Pb（^8B，^7Be，p）^<208>Pb过程进行了广泛的研究，该过程模拟了太阳中微子问题的关键过程^7Be（p，gamma）^8B反应。我们的结果表明E2分量非常小，理论上估计这会给^8B库仑解离结果带来严重问题。第二次实验将实现对S_的新测定<17>。我们还进行了<12>与热pp模式燃烧过程相关的^ N解离实验，在Louvain la Neuve进行了^<19>Ne（p，gamma）^<20>Na反应的直接测量。该反应被认为是CNO区向NeNa区质量流动的关键。实验只能给出横截面的上限，这已经比预测小得多。对^<13>N（p，gamma）^<14>O反应进行了另一种直接测量，该反应是从常规CNO循环点燃热CNO循环的关键。该实验旨在通过提高数据的准确性来提供库仑解离和直接捕获方法之间的公平和精确的比较，因为这两种方法都曾被应用于^<13>N（p，gamma）^<14>O，并且结果在误差范围内彼此一致。在立教建造了一个高效率的伽马射线探测装置，并带到新鲁汶，用于测量放射性^ N束与氢靶引起的辐射俘获反应产生的5.17 MeV伽马射线<13>。分析正在进行中。

项目成果

T.Motobayashi et al.: "Coulomb Dissociation of ^8B and the ^7Be(ρ,γ)^8B Reaction at Low Energies" Physical Review Letters. 73. 2680-2683 (1994)

T. Motobayashi 等人：“低能量下 ^8B 的库仑解离和 ^7Be(ρ,γ)^8B 反应”物理评论快报 73. 2680-2683 (1994)。

T. Motobayashi et al.: "Coulomb Dissociation of ^8B and the ^7Be(p,γ)^8B Reaction at Low Energies" Physical Review Letters. 73. 2680-2683 (1994)

T. Motobayashi 等人：“低能量下 ^8B 的库仑解离和 ^7Be(p,γ)^8B 反应”物理评论快报 73. 2680-2683 (1994)。

S. Kubono: "Proton-Rich Unstable Nuclei in Explosive Hydrogen Burning" Nuclear Physics. A588. 305c-312c (1995)

S. Kubono：“爆炸性氢燃烧中的富质子不稳定核”核物理。

N. Iwasa et al.: "Study of the ^7Be(p,γ)^8B Reaction with Coulomb Dissociation Method" Journal of Physical Society of Japan. 65(印刷中). (1996)

N. Iwasa 等人：“用库仑解离法研究 ^7Be(p,γ)^8B 反应”，日本物理学会杂志 65（出版中）。

T. Motobayashi: "Coulomb Dissociation of ^8B and Solar Neutrino Problem" Nuclear Physics. A588. 319C-326C (1995)

T. Motobayashi：“^8B 的库仑解离和太阳中微子问题”核物理。