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Reaction mechanism of Coulomb dissociation induced by high-speed heavy ions

高速重离子诱导库仑解离的反应机理

基本信息

批准号：
08454069
负责人：
MOTOBAYASHI Toru
金额：
$ 4.48万
依托单位：
RIKKYO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454069/
关键词：
Coulomb dissociation E2 component angular distribution ^7Be(P,gamma)^8B reaction ^8Be(P,gamma)^9B reaction large vacuum chamber solar neutrino hot pp mode クーロン分解反応放射捕獲反応 hot pp chain 不安定核角度相関バックグラウンド反応機構核力分解クラスターモデル /

项目摘要

Reaction mechanism of intermediate-energy Coulomb dissociation has been studied by precise measurements of angular distribution and angular correlation of the fragments. A large vacuum chamber has been constructed as a housing of a plastic scintillator hodoscopes. The chamber was installed in a experimental hail of RIKEN Accelerator Research Facility, and was used for experiments with radioactive nuclear beams. Background-free measurements become possible for the relative energy lower than 0.5 MeV.The ^<208>Pb(^8B, ^7Be p)^<208>Pb and ^<208>Pb(^9C, ^8B p) ^<208>Pb reactions were studied. The primary aim of the measurements are to determine the ^7Be (p, gamma)^8B and ^8B(p, gamma)^9C reactions. The former reaction produce high-energy solar-neutrinos, and the latter is a key reaction in the hot pp mode nuclear burning in stars. In the Coulomb dissociation method, a one-step El transition mechanism is assumed in the process of extracting the (p, gamma) cross section. However, possible small mixture of E2 transition had been pointed out. We notice that the fragments' angular distributions are different for El and E2 transitions. In the measurements, the scattering angle up to 100 was covered by the new setup to obtain complete distributions. The results suggested very small E2 components which do not affect the extracted (p, gamma) cross sections.

通过对碎片角分布和角关联的精确测量，研究了中能库仑离解的反应机理。一个大的真空室已被构造为塑料闪烁体hodoscope的外壳。该室被安装在RIKEN加速器研究设施的实验大厅中，用于放射性核束的实验。在相对能量低于0.5MeV时，无本底测量成为可能。研究了^<208>Pb（^8B，^7Be p）^<208>Pb和^<208>Pb（^9C，^8B p）^<208>Pb反应。测量的主要目的是确定^7Be（p，gamma）^8B和^8B（p，gamma）^9C反应。前者产生高能太阳中微子，后者是恒星热pp模式核燃烧的关键反应。在库仑解离方法中，在提取（p，γ）截面的过程中假设一步El转变机制。然而，已经指出了可能的E2跃迁的小混合物。我们注意到E1和E2跃迁的碎片角分布是不同的。在测量中，新的设置覆盖了高达100的散射角，以获得完整的分布。结果表明，E2分量非常小，不会影响提取的（p，伽马）截面。