近二十年来，中子星表面由 12 C+ 12 C熔合反应触发的超级X-射线暴天文观测结果，无法用现有的基于外推得到的 12 C+ 12 C熔合反应率解释，因此对极低库仑势垒能量下 12 C+ 12 C熔合反应截面进行测量成为了核天体物理研究的一个热点。然而，超级暴典型的 12 C+ 12 C熔合反应伽莫夫窗口为1.5±0.3 MeV，远低于熔合反应库仑势垒。这使得用直接测量方法对该能区内极低的熔合反应截面进行研究成为一个巨大的挑战。特洛伊木马方法实验（THM）是目前唯一能给出伽莫夫窗口内各出射道激发函数的带电粒子测量实验，然而其结果目前仍存在很大争议。本工作回顾了 12 C+ 12 C熔合反应直接测量实验的研究现状，并对THM的数据分析结果提出了新的解读。结合全同玻色子体系理论对THM提取的复合核 24 Mg激发态进行讨论，首次给出 12 C+ 12 C熔合反应入射道无量纲约化宽度推荐平均值θ 2 =0.031，与反对称分子动力学模型（AMD）在相应能区的理论预言相一致。

Nuclear astrophysics is a rapidly developing interdisciplinary field of research that has received extensive attention from the scientific community since the mid-twentieth century. Broadly, it uses the laws of extremely small atomic nuclei to explain the evolution of the universe. Owing to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments, several critical astrophysical problems remain unsolved. To achieve a better understanding of astrophysics, it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical models. Direct measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions influence stellar evolution. Given the challenges involved in measuring the extremely low cross sections of nuclear reactions in the Gamow peak and preparing radioactive targets, indirect methods, such as the transfer reaction, coulomb dissociation, and surrogate ratio methods, have been developed over the past several decades. These are powerful tools in the investigation of, for example, neutron-capture (n, γ ) reactions with short-lived radioactive isotopes. However, direct measurement is still preferable, such as in the case of reactions involving light and stable nuclei. As an essential part of stellar evolution, these low-energy stable nuclear reactions have been of particular interest in recent years. To overcome the difficulties in measurements near or deeply within the Gamow window, the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal solution. Therefore, underground experiments have emerged as a new and promising direction of research. In addition, to better simulate the stellar environment in the laboratory, research on nuclear physics under laser-driven plasma conditions has gradually become a frontier hotspot. In recent years, the CIAE team conducted a series of distinctive nuclear astrophysics studies, relying on the Jinping Underground Nuclear Astrophysics platform and accelerators in Earth’s surface laboratories, including the Beijing Radioactive Ion beam Facility, as well as other scientific platforms at home and abroad. This research covered nuclear theories, numerical models, direct measurements, indirect measurements, and other novel approaches, achieving great interdisciplinary research results, with high-level academic publications and significant international impacts. This article reviews the above research and predicts future developments.

The ^12C+ ^12C fusion is one of the most important reactions in modern nuclear astrophysics. The trend and magnitude of the reaction rate within the Gamow window strongly influence various astrophysical processes. However, direct measurement of this reaction is extremely difficult, which makes it necessary to develop indirect methods. In this study, the ^23Na+p reaction system was used to study the compound nucleus ^24Mg . We employed a thick-target inverse kinematics method combined with the γ -charged-particle coincidence technique to measure the proton and α exit channels of ^24Mg . Technical details of the ^23Na+p thick-target inverse kinematics experiment and analysis are presented herein.

We present a precise measurement of the asymptotic normalization coefficient (ANC) for the 16 O ground state (GS) through the 12 C( 11 B, 7 Li) 16 O transfer reaction using the Quadrupole‐3‐Dipole (Q3D) magnetic spectrograph. The present work sheds light on the existing discrepancy of more than 2 orders of magnitude between the previously reported GS ANC values. This ANC is believed to have a strong effect on the 12 C( α , γ ) 16 O reaction rate by constraining the external capture to the 16 O ground state, which can interfere with the high-energy tail of the 2 + subthreshold state. Based on the new ANC, we determine the astrophysical S -factor and the stellar rate of the 12 C( α , γ ) 16 O reaction. An increase of up to 21% in the total reaction rate is found within the temperature range of astrophysical relevance compared with the previous recommendation of a recent review. Finally, we evaluate the impact of our new rate on the pair-instability mass gap for black holes (BH) by evolving massive helium core stars using the MESA stellar evolution code. The updated 12 C( α , γ ) 16 O reaction rate decreases the lower and upper edges of the BH gap about 12% and 5%, respectively.

16 N的β延迟α衰变能谱在Ec.m.≈1.2 MeV处有一低能峰,该α峰的形状和高度可用于约束12 C(α,γ)16 O反应截面的E1部分,对其进行测量具有重要意义.本工作尝试采用重离子注入法对其进行测量,在兰州重离子加速器国家实验室RIBLL1放射性束流线上产生了16 N放射性束流并将其注入到双面硅微条探测器(DSSD)中,利用DSSD对其β延迟α能谱进行了测量.通过选用薄的DSSD探测器、DSSD正反面能量符合关系以及DSSD点火数约束等方法,显著减小了16 N衰变产生的电子对α能谱测量的干扰,将α能谱的测量阈值降低到800 keV左右,成功观测到了Ec.m.≈1.2 MeV处的低能峰.该方法为间接研究12 C(α,γ)16 O反应率开辟了一条新的实验方法.

22Ne(α,n)25Mg is one of the main neutron sources of the s process. 22Ne is produced by the 14N(α, γ)18F(β+)18O(α, γ)22Ne reaction chain in the helium burning, thus, the production rate of 22Ne is dominated by 14N(α,γ)18F and 18O(α,γ)22Ne. At the astrophysical relevant temperatures, the 18O(α,γ)22Ne reaction rates are determined by several low-energy resonances. In this work, the 18O(α,γ)22Ne reaction was measured at the 400 kV accelerator of Jinping Underground Nuclear Astrophysics experiment (JUNA). The γ-ray yields of the resonances between 470 to 770 keV were obtained.

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 reso-nance strength and ground state feeding factor are determined to be 3.8±0.3 ×10-10 eV and 0.66 ± 0.04,respectively.The results are in agreement with those reported in the previous direct under-ground 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.

The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest. Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei. The development of rare isotope accelerators offers opportunities for such studies. To date, many relevant measurements have been performed at accelerators using the projectile fragmentation technique, while the measurements at accelerators using isotope separator on-line (ISOL) systems are still quite scarce. In this work, we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility (BRIF) by measuring the angular distribution of elastic scattering for the stable nucleus $$^{23}$$ Na from the doubly magic nucleus $$^{40}$$ Ca at energies above the Coulomb barrier. The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3D magnetic spectrograph using the non-ISOL beam at nearly the same energy. This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.

Proton capture reactions on Mg isotopes are significant in the Mg-Al cycle in stellar H-burning. In particular, the resonance strengths and branching ratios of low-energy resonances in Mg-25(p, gamma)Al-26 reactions determine the production of Al-26, which is one of the most important long-lived radioactive nuclei in nuclear astrophysics. In this article, we report our first experiment using the intense proton beam of approximately 2 mA provided by the JUNA accelerator ground laboratory and a new technique that can minimize the composition change of targets under intense beam irradiation. The resonance strengths and branching ratios of E = 214, 304, and 326 keV resonances in the reactions of Mg-24( p, gamma)Al-25, Mg-25(p, gamma)Al-26, and Mg-26(p, gamma)Al-27, respectively, were measured with high accuracy. The success of this experiment provides a good calibration for the nuclear astrophysical experiment at the Jinping underground laboratory.

The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest. Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei. The development of rare isotope accelerators offers opportunities for such studies. To date, many relevant measurements have been performed at accelerators using the projectile fragmentation technique, while the measurements at accelerators using isotope separator on-line(ISOL) systems are still quite scarce. In this work, we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility(BRIF) by measuring the angular distribution of elastic scattering for the stable nucleus 23 Na from the doubly magic nucleus 40 Ca at energies above the Coulomb barrier.The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3 D magnetic spectrograph using the nonISOL beam at nearly the same energy. This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.