对放射性核的弱r过程反应的首次测量
M Williams1, C Angus2,3, A M Laird2,3
1University of Surrey, School of Mathematics and Physics, Guildford, GU2 7XH, United Kingdom.
Physical review letters
|April 7, 2025
概括
这项研究首次使用放射性离子束测量了关键的核反应截面. 结果显示反应速率低于预测,影响了宇宙中的丰度.
科学领域:
- 核天体物理学 核天体物理学
- 核物理 核物理 核物理
- 太空化学 太空化学
背景情况:
- 了解重元素的起源需要精确了解核反应速率.
- 快速中子捕获过程 (r过程) 负责合成比铁更重的元素.
- 对于弱r过程反应,特别是那些涉及不稳定同位素的反应,实验数据很少.
研究的目的:
- 通过实验确定 ^{94}Sr(α,n) ^{97}Zr 和 ^{86}Kr(α,n) ^{89}Sr 反应的截面.
- 用放射性离子束提供了使用放射性离子束的弱r过程反应截面的首次测量.
- 将实验结果与理论预测进行比较,并评估它们对核合成模型的影响.
主要方法:
- 使用一种新的固体目标系统与薄膜.
- 使用放射性离子束进行Sr,α,n,Zr反应测量.
- 在5GK的Gamow窗口内,在特定的质量中心能量下测量反应产量.
- 通过快速的马射线检测确定反应产物,并与反弹质谱仪的重离子相吻合.
主要成果:
- 获得了Sr,Zr和Kr,N,Sr的第一个截面测量.
- 两种反应的测量截面都比理论预测要小得多.
- 对于{94}Sr(α,n) ^{97}Zr的反应速率降低了一个数量级,低于5 GK.
结论:
- 实验发现挑战了现有的核合成模型对r-process.
- 预计Sr,α,n,Zr的减少反应速率将改变预测的丰度.
- 这项工作强调了对不稳定的同位素的实验数据在理解宇宙元素丰度方面的重要性.
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