E1/E2 Ratio of ^<12>C(α, γ)^<16>O Reaction in Energy Regin of Astrophysical Interest

天体物理学能量区域中^<12>C(α, γ)^<16>O反应的E1/E2比率

• 批准号: 10440077
• 负责人: MORINOBU Shunpei
• 金额: $ 8.19万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10440077/
• 关键词: Nuclear astrophysics; He-burning; ^<12>C+γ; Recoil mass-analysis; γ-ray angular distribution; Accelerator development

Although the rate of the α-capture reaction, ^<12>C+α→^<16>O+γ, is of crucial importance in the scenario of evolution of main sequence stars, the experimental determination has long been hampered by great technical difficulties arising from extremely low cross section. The aim of the present investigation was to facilitate the rate measurement by detecting ^<16>O ions from the inverse kinematics reaction ^<12>C(^4He, ^<16>O) γ and to determine the E1/E2-capture ratio from the γ-ray angular distribution extracted from the analysis of the ^<16>O energy spectrum. In order to overcome the experimental difficulty, many technical developments were carried out both in the tandem accelerator and in the measuring system.1.Developments of the tandem acceleratorTo cope with very small cross section, the accelerator developments were carried out to make high-current beams with good quality available. A new acceleration mode of strong focusing principle was developed and a large aperture gas charge … More -stripper was installed. These altogether achieved 1000 times increase in the low energy ^<12>C beam intensity and 2-5 times improvement in the beam emittance. Beam pulsing was also made available by a newly developed buncher-chopper system.2.Development of the measuring systemIn order to separate ^<16>O ions from the high flux of beam particles, a new recoil separator was constructed and established as an excellent tool for the measurement by the detailed ion-optical investigation. A newly developed ^4He gas target was also installed. The method of measuring γ-ray angular distribution from the particle energy spectrum was examined using the ^<16>O (^<13>C, ^<12>C[2+])^<17>O and ^<16>O (^<ll>B, ^<12>C[2+] )^<15>N reactions and was found to work quite effectively in attaining the aim of the measurement.3.Test measurement and experimentThe test measurements were carried out and it was observed that three kinds of backgrounds were present in the particle spectrum. The origins were identified and two of them were successfully eliminated. To remove the last one, the beam line is being remodeled. The measurement has been started at a high energy of E_<cm>=2.4MeV, where the yield is expected relatively high. The energy of the measurement will be gradually reduced along with the repetition of test and improvement as above. Less

虽然α-俘获反应^<12>C+α→^<16>O+γ的速率在主序星的演化过程中至关重要，但由于反应截面极小，实验测定一直受到技术上的限制。本研究的目的是通过检测<16>来自逆运动学反应^<12>C（^4He，^<16>O）γ的^ O离子来促进速率测量，并从^ O能谱分析中提取的γ射线角分布来确定E1/E2俘获比<16>。为了克服实验上的困难，在串列加速器和测量系统方面进行了许多技术上的改进。1.串列加速器的改进为了科普非常小的截面，进行了加速器的改进，以获得高质量的强流束。提出了一种基于强聚焦原理的新型加速方式， ...更多信息 - 安装了剥离器。这些总共实现了低能12 C束流强度的1000倍增加<12>和束流发射度的2-5倍改善。2.测量系统的研制为了<16>从高通量的束流粒子中分离出2 O离子，我们研制了一种新型的反冲分离器，并通过详细的离子光学研究，建立了一种很好的测量工具。还安装了一个新开发的^4He气体靶。用^<16>O（^<13>C，^<12>C[2+]）^<17>O和^<16>O（^<ll>B，^<12>C [2 +]）^<15>N反应考察了从粒子能谱中测量γ射线角分布的方法，发现能有效地达到测量目的。3.测试测量和实验进行了测试测量，观察到粒子能谱中存在三种本底。找到了源头，成功排除了其中两个。为了删除最后一个，正在重新建模光束线。在E_2 =2.4MeV的高能量下开始测量<cm>，预期产额较高。测量的能量将随着上述试验和改进的重复而沿着逐渐降低。少

项目成果

N.Ikeda: "Role of Multi-Step Processes in ^<16>O(^<11>B, ^<12>C)^<15>N at 41.25 MeV"Kyushu University Tandem Accelerator Report, KUTL-7. 7. 32-34 (2000)

N.Ikeda：“41.25 MeV ^<16>O(^<11>B, ^<12>C)^<15>N 中多步过程的作用”九州大学串联加速器报告，KUTL-7。

K.Sagara: "Accel-Decel Strong Focus for a Tandem Accelerator"Kyushu University Tandem Accelerator Report, KUTL-7. 7. 146-150 (2000)

K.Sagara：“串联加速器的加减速强焦点”九州大学串联加速器报告，KUTL-7。

K.Turuta: "Construction of Recoil Mass Separator"Kyushu University Tandem Accelerator Report, KUTL-7. 7・. 102-103 (2000)

K.Turuta：“反冲质量分离器的构造”九州大学串联加速器报告，KUTL-7·102-103（2000）。

S.Kouda: "A new method of accurate polarization measurement on isobaric analog resonance to detect non-conservation" Nucl.Instr.and Meth.A. 420. 380-391 (1999)

S.Kouda：“一种对同量异位模拟共振进行精确偏振测量以检测非保守性的新方法”Nucl.Instr.and Meth.A。

Y.Tsubusaki: "Test of Beam Bunching System"Kyushu University Tendem Accelerator Report, KUTL-7. 7. 151-154 (2000)

Y.Tsubusaki：“束束系统的测试”九州大学Tendem加速器报告，KUTL-7。