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锦屏深地核天体物理实验(JUNA)的首个结果:25Mg(p,γ)26Al反应92 keV共振的精确测量(英文)
First result from the Jinping Underground Nuclear Astrophysics experiment JUNA: precise measurement of the 92 keV 25Mg(p, γ)26Al resonance
【摘要】 银河系星际介质中的26Al衰变发射的1.809 MeVγ射线是γ天文学的主要观测对象之一,是银河系中正在进行核合成的关键证据,也为核合成理论与天文观测进行比较提供一个重要基准.在大质量恒星氢燃烧中, 26Al主要通过25Mg(p,γ)26Al反应产生,因此该反应在1.809 MeVγ射线研究中起着重要的作用.在天体环境温度为0.1 GK左右时,25Mg(p,γ)26Al天体物理反应率主要由92 keV共振俘获过程决定.作为在中国锦屏地下实验室(CJPL)中锦屏核天体物理实验(JUNA)装置上进行的首个实验,本工作对25Mg(p,γ)26Al反应的92 keV共振进行了精确的实验测量,得到了该共振的共振强度为ωγ=(3.8 0.3) 10-10 eV,基态分支比为f0=0.66 0.04.与之前的工作相比,本工作大大提高了92 keV共振数据的精度.基于测量的92 keV共振参数和以前的间接测量结果,得到了精度最高的25Mg(p,γ)26Al天体物理反应率.结果表明,在0.1 GK左右时,新的反应率比REACLIB数据库中采用的反应率大2.4倍,这将导致26Al和宇宙1.809 MeVγ射线的产额提高.同时,新反应率也将对理解太阳系的形成、球状星团的元素丰度反相关等问题提供重要的数据支撑.
【Abstract】 The 25Mg(p, γ)26Al reaction plays an important role in the study of cosmic 1.809 MeV γ-ray as a signature of ongoing nucleosynthesis in the Galaxy. At astrophysical temperature around 0.1 GK, the 25Mg(p, γ)26Al reaction rates are dominated by the 92 keV resonance capture process. We report a precise measurement of the 92 keV 25Mg(p, γ)26Al resonance in the day-one experiment at Jinping Underground Nuclear Astrophysics experiment(JUNA) facility in the China Jinping Underground Laboratory(CJPL). The resonance strength and ground state feeding factor are determined to be 3.8 ± 0.3 ×10-10 eV and0.66 ± 0.04, respectively. The results are in agreement with those reported in the previous direct underground measurement within uncertainty, but with significantly reduced uncertainties. Consequently, we recommend new 25Mg(p, γ)26Al reaction rates which are by a factor of 2.4 larger than those adopted in REACLIB database at the temperature around 0.1 GK. The new results indicate higher production rates of 26gAl and the cosmic 1.809 MeV γ-ray. The implication of the new rates for the understanding of other astrophysical situations is also discussed.
【Key words】 Nuclear astrophysics; Underground laboratory; Cosmic γ ray; Resonance reaction; 26Al;
- 【文献出处】 Science Bulletin ,科学通报(英文版) , 编辑部邮箱 ,2022年02期
- 【分类号】P14
- 【被引频次】4
- 【下载频次】102