锦屏深地核天体实验探究AGB星氟超丰问题  

Examining the fluorine overabundance problem by conducting Jinping deep underground experiment

作　　者：陈银吉 张立勇 CHEN Yinji;ZHANG Liyong(Key Laboratory of Beam Technology of Ministry of Education,College of Nuclear Science and Technology,Beijing Normal University,Beijing 100875,China;Institute of Radiation Technology,Beijing Academy of Science and Technology,Beijing 100875,China)

机构地区：[1]北京师范大学核科学与技术学院教育部离子束技术重点实验室,北京100875 [2]北京市科学与技术研究院辐射技术研究所,北京100875

出　　处：《核技术》2023年第11期49-54,共6页Nuclear Techniques

基　　金：国家自然科学基金(No.12075027,No.11490562)资助。

摘　　要：氟是核天体物理学中最感兴趣的元素之一。长期以来,渐近巨星分支(Asymptotic Giant Branch,AGB)中的氟超丰问题一直难以用天体物理标准模型来解释。基于锦屏深地核天体物理实验装置(Jinping Underground laboratory for Nuclear Astrophysics,JUNA),利用强流加速器和高效的4πBGO探测器直接测量了AGB星中氟破坏反应^(19F)(p,αγ)^(16)O。将19F(p,αγ)^(16)O反应的测量推进到有史以来最低的72.4 keV,测量结果覆盖了整个天体物理感兴趣的伽莫夫能区,与之前的理论外推差异很大,且不确定度得到了极大降低,为天体物理模型计算提供了可靠的核物理输入量。[Background]Nuclear reactions have been crucial in the evolution of the universe since the big bang.The cross section of nuclear reaction that occurs during the early evolution of the star is extremely low,so it cannot be accurately measured in a ground laboratory.The China Jinping Underground Laboratory(CJPL),which is the deepest operational underground laboratory in the world,offers unique ultra-low background conditions that facilitate the direct evaluation of the nuclear reactions occurring during the early evolution of stars.[Purpose]Asymptotic giant branch(AGB)stars are thought to be the major contributor to Galactic fluorine production.However,the astronomical fluorine overabundance cannot be explained by using the current standard AGB models.Direct measurements of^(19)F(p,αγ)^(16)O reactions can help solve this problem.[Methods]Experiments were conducted on a high-current 400-kV JUNA(Jinping Underground laboratory for Nuclear Astrophysics)accelerator at the CJPL.A 4πBGO detector array was specially designed for the JUNA project.[Results]The astrophysical S factors in the energy region of 72.4~188.8 keV were experimentally derived for the first time,covering the astrophysical Gamow window.The thermonuclear^(19)F(p,αγ)^(16)O rate was determined at a low temperature of about 0.05 GK for astrophysical modeling.The present low-energy S factors significantly deviated from previous theoretical predictions,and the associated uncertainties were considerably reduced.

关 键 词：锦屏深地核天体物理 氟超丰 核反应 天体物理S因子 

分 类 号：TL8[核科学技术—核技术及应用]