We investigate the sensitivity of calcium production to nuclear reaction rates of a 40 solar-mass Population III star using 1D multi-zone stellar models. A comprehensive nuclear reaction network was constructed, and all (p,γ) and (p,α) reaction rates were individually varied by a factor of 10 up and down, identifying 13 preliminary key reactions for calcium production. To propagate the reaction rate uncertainties on calcium production, two sets of Monte Carlo simulations were performed for these key reactions: one adopting STARLIB reaction rates and the other incorporating updated rates from recent experimental data and evaluations. Our results show that Monte Carlo simulations using the updated rates show good agreement with the observed calcium abundance of the extremely iron-poor star SMSS J031300.36-670839.3 within the 68 Additionally, comparisons between 20 solar-mass and 40 solar-mass Population III stellar models confirm that the latter, with updated reaction rates, is more capable of reproducing the observed Ca abundance and [Ca/Mg] ratio.

The -delayed neutron emission probability ( P_n ) is a key observable for characterizing the decay strength of very neutron-rich nuclei and the rapid neutron capture process in nuclear astrophysics. A Long Helium-3 Neutron Array (LHENA) has been developed at the Beijing Rare Isotope Facility (BRIF) to enable P_n measurements using Isotope Separator On Line (ISOL) pulsed beams. LHENA is designed to work in conjunction with a tape driver and auxiliary detectors, so that particles, -delayed neutrons and γ rays emitted from the implanted nuclei can be measured simultaneously in cyclic mode. LHENA consists of 21 long ^3 He proportional counters embedded in a polyethylene moderator with a two-ring configuration, which provides a flat neutron detection efficiency up to 3 MeV according to our Geant4 simulations. The detection efficiency has been experimentally determined to be 16.4( ± 0.4 ) ^51 V(p,n) ^51 Cr reaction for neutron energies in the 120–700 keV range. A good efficiency flatness and a very low background have been verified for LHENA, laying a solid foundation for the first P_n measurement using very neutron-rich Rb isotopes at BRIF.

This paper addresses a long-standing problem in astrophysics-the origin of the solar system abundance of the proton-rich isotope Mo-94 by proposing a valuable novel mechanism. The main contribution of this work is that it challenges the traditional view of "Mo-94 as a pure p-process nuclide". For the first time, it demonstrates that within the s-process environment of low-mass AGB stars, a new s-process path (Zr-93 -> Nb-93 -> Nb-94 -> Mo-94) for producing Mo-94 can be opened, enabled by the significant enhancement of the effective decay rates of Zr-93 and Nb-94 due to the high-temperature astrophysical environment. The results show that this s-process channel can contribute up to a maximum of approximately 10.6% to the solar system abundance of Mo-94. This work provides a new s-process perspective on the origin of Mo-94 and has implications for reevaluating the sources of other "shielded" p-nuclei.

Windowless gas targets avoid the beam-energy loss and straggling introduced by entrance foils and are therefore well suited for direct measurements of low-energy nuclear reactions. A windowless gas-target system designed for operation with milliampere beams has been developed for the Jinping Underground Nuclear Astrophysics facility (JUNA). The system combines three-stage differential pumping, closed-loop gas recovery and purification, a constant-temperature power-compensation calorimeter, and a position-resolved target-thickness monitor based on secondary elastic scattering. Stable operation was achieved over a target-pressure range of 1-3 mbar, with pressure fluctuations below 1

The 26Mg(p, γ)27Al reaction, as part of the Mg-Al cycle, is closely related to the abundance ratio of 26Al to 27Al in stars. It also has a direct connection to the Mg-Al anti-correlation observed in globular clusters (GCs). Its reaction rate is determined by multiple known and unknown low-energy resonances. In this work, we measured the angular distributions of the proton transfer reaction 26Mg(7Li, 6He)27Al populating three levels at excitation energies from 8.324 MeV to 8.597 MeV using the HI-13 tandem accelerator and a high-precision magnetic spectrograph. Proton spectroscopic factors were extracted from the angular distributions corresponding to three states, and the resonance strengths which make contributions to the reaction rate were updated. At the same time, the latest calculated reaction rate shows the result for the 52.8 keV resonance significantly increases the total reaction rate at T9 < 0.03.

Present and future rare isotope accelerator facilities provide new opportunities to explore the structure of unstable nuclei. We report the measurements of the elastic scattering angular distributions of 21Na and 22Na on the doubly magic 40Ca above the Coulomb barrier energies, using high-purity post-accelerated ISOL beams from Beijing Radioactive Ion Beam Facility (BRIF). Angular distributions were measured with a silicon detector telescope array, and relative cross sections were determined with a CaF2 target on Au backing. The data were well reproduced by optical model calculations with Woods–Saxon and USNP potentials, the latter giving better agreement. These results confirm the stable operation and performance of the BRIF ISOL production and post-acceleration system, demonstrate its capability to provide radioactive beams of useful intensity and purity for future investigations of reaction dynamics and astrophysically relevant processes involving proton-rich nuclei, and simultaneously extend proton-rich elastic scattering studies to heavier systems.

Type I X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars, involving hundreds of nuclei and thousands of reactions with larger uncertainties in reaction rates. To investigate the impact of nuclear reaction rate uncertainties on type I X-ray burst nucleosynthesis, comprehensive Monte Carlo simulations were performed with temperature-independent and -dependent variations in reaction rates using the REACLIB and STARLIB libraries, respectively. A total of 1711 (p, gamma), (p, alpha), (alpha, p), and (alpha, gamma) reaction rates are varied simultaneously along with their inverse reactions via detailed balance. For the first time, it has been found that Monte Carlo sampling with larger perturbations to these reaction rates may lead to multipeak abundance distributions for certain isotopes, such as 64Zn and 55Co. These multipeak structures arise not only from coupled reactions but also from single reactions in some cases. Our studies also confirm previously identified key reactions and provide more robust lists that deserve priority consideration in future studies.

20Na is a well-known β-delayed α emitter, owing to the large decay energy of 20Na above the α + 16O threshold in the A=5α daughter nucleus 20Ne. In this work, the decay property of 20Na is investigated in detail via the β-γ β-α and β-γ-α coincidence spectroscopy. As the day-one experiment of the Beijing Rare Isotope Facility (BRIF), the intense 20Na beam was produced using the Isotope Separator On Line (ISOL) technique through the 100 MeV proton bombarding a stack of MgO as a thick target. Specific interest was focused on the exotic decay mode of 20Na; the previously reported low-energy α lines at 713 and 846 keV were confirmed, and several weak β-γ-α decay sequences were clearly identified for the first time, thanks to the strong resolving power of α-γ coincidence spectroscopy. The decay properties of 20Na are compared to the shell model calculation, which agree reasonably well with the allowed β transition strengths and subsequent electro-magnetic transitions with the use of the sd shell-model space with the USDB interaction.

The unique resonance features in the ^12C+^12C fusion reaction lead to significant fluctuations in the branching ratio R_p/α=σ_p/σ_α, making it difficult to determine the R_p/α at astrophysical energies. By combining Hauser–Feshbach statistical-model calculations with constraints from direct charged-particle and gamma-ray measurements, we investigate the energy dependence of the averaged R_p/α and predict its behavior within the Gamow window. Owing to the strong energy dependence of R_p/α, the corresponding reaction-rate ratios, ⟨ σv ⟩_p / ⟨ σv ⟩_α, during core and shell carbon burning are determined to be 0.29, 0.45, and 0.52 at T_9 = 0.5, 1.0, and 1.2, respectively, significantly lower than the widely adopted CF88 constant value of 0.79. The implications of the revised ⟨ σv ⟩_p / ⟨ σv ⟩_α ratio for stellar nucleosynthesis and white-dwarf evolution are also discussed.

The Beijing Radioactive Ion-beam Facility (BRIF), based on the Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60 to 300 keV, and post-accelerated beams in the energy range from 3 to 10 MeV/u for nuclei with mass numbers of A < 80. For nuclei with A up to 170, energies are still able to reach 3 MeV/u. This facility offers opportunities to address key questions of current interest in nuclear astrophysics, nuclear structure and reactions of unstable nuclei. In this review we present a comprehensive introduction to the BRIF and the typical experimental instruments installed on it, and then summarize current experimental results on unstable Na and Rb isotopes and future plan for development of the BRIF to improve its performance.

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。

The C-12+C-12 fusion reaction at deep subbarrier energies is important for understanding the carbon burning process in massive star and explosive binary systems. However, its reaction rates are very difficult to measure directly or evaluate by simple extrapolation due to the extremely small cross sections and complex resonance structures near the Gamow window. In this work, we use one of its exit channels, i.e. Na-23 + p to populate the excited states of the compound nucleus Mg-24 via the conventional thick-target inverse kinematics method. By applying gamma-charged particle coincidence, we have obtained excitation functions for the proton and a emission channels, respectively, and derived the resonance parameters through a simultaneous multi-channel R-matrix analysis. It is clear that a series of discrete resonances exist in the most relevant excitation energy region of Mg-24. The astrophysical S-factor of the C-12+C-12 fusion reaction is evaluated by adopting a systematic reduced width for the entrance channel. In particular, branching ratios of the dominant four decay channels are estimated across the entire Gamow window of the C-12+C-12 fusion reactions. Significant fluctuations are shown that may have strong impacts on the final outcome of the carbon burning process.

Sm-146 is an important nuclide for both geochronological and astrophysical applications, its precise half-life value is essential for accurate geological applications. Nevertheless, significant discrepancies exist in the measured half-life values of Sm-146. A new experimental method has been proposed by merely measuring the total amount of Eu-146 and the decay of Sm-146, corresponding alpha and gamma spectrometers have been developed for the measurement. The preliminary experiment has been carried out in HI-13 tandem accelerator of China Institute of Atomic Energy. Based on alpha and gamma measurements, the half-life of Eu-147 has been double checked and the results agree well with existing values, which gives a verification for the reliability of our half-life measurement systems. The half-life of Eu-146 has been updated to 4.21 +/- 0.05 days, which is 9% lower than the value reported in the database. Based on our analysis, this difference has a significant impact on the determination of the number of Eu-146 atoms, and consequently has an equivalent impact on the measurement of Sm-146 half-life.

Nuclear β-decay plays a pivotal role at various stages of stellar evolution. However, the effective decay rates of nuclei in astrophysical environments may differ significantly from their laboratory values. This paper presents a detailed methodology for calculating nuclear half-life under the influence of temperature, electron density, ionization and incomplete thermal equilibrium. We analyze the impact of astrophysical conditions on the β-decay of 26 Al, 59 Fe, 79 Se and 205 Pb, revealing substantial variations in their effective half-lives within stellar environments. These changes lead to significant differences in nucleosynthetic yields, underscoring the critical importance of accounting for environmental effects when modeling nuclear decay rates.

A low-background γ spectrometer named the Gamma spectrometer for Nuclear Activation Studies (GNAS) was developed to detect scarce γ radioactivity, with a special focus on conducting activation experiments in nuclear astrophysics. It consisted of a well-type HPGe detector surrounded by optimized multi-layer shielding, which reduced the laboratory background counting rate by 99.5 γ line of ^7Be . The near 4π geometry of the HPGe detector introduces a severe true coincidence summing (TCS) effect along with its high detection efficiency. To determine the intrinsic detection efficiency and correct for the TCS effect, a Monte Carlo simulation method was developed with the Geant4 toolkit. The detector model was optimized by matching the simulated full energy peak (FEP) statistics with those of a ^137Cs monoenergetic source and calibrated ^55,57,58Co sources produced by low-energy proton beam bombardment of natural iron. The intrinsic detection efficiency curve was obtained, and an algorithm for the correction of the TCS effect was programmed using decay data from the ENSDF library and Nuclear Wallet Cards. The GNAS fulfills the requirements of the ongoing activation measurement of proton- and alpha-induced reactions in nuclear astrophysics on the ground and at the Jinping Underground Nuclear Astrophysics (JUNA) facility.

聚变三乘积（Fusiontriple product）是可自持核聚变反应的重要判据,它利用聚变堆中核燃料的原子核数密度n、等离子体能量约束时间τ E 、燃料温度T这三个物理量来判断聚变反应堆是否能满足实现自持核聚变的能量平衡条件。本研究探讨了以 6 Li-D作为核燃料的聚变反应系统,并考虑了相对论效应对轫致辐射的影响以及能量回收效率对能量增益因子Q的影响,计算了忽略回旋辐射条件下 6 Li-D聚变反应系统产生Q=1的能量增益时的聚变三乘积(n i Tτ E =4.9×10 23 m -3 ·keV·s)。结果表明, 6 Li-D可以作为核聚变燃料实现正的能量增益,但其实现自持核聚变的点火条件相对于D-T核聚变的点火条件来说更为困难。

Nuclear physics has been expanding rapidly to the limits of nuclear stability due to the increase of available rare isotopes[1].The nuclear binding energies of light loosely bound nuclei near the drip-lines are lower than those of stable isotopes located in the β-stability valley.Light loosely bound nuclei could exhibit exo-tic properties,such as neutron halo,neutron skin and two-proton emission.

To investigate the impact of nuclear reaction rate uncertainties on type I X-ray burst nucleosynthesis, comprehensive Monte Carlo simulations are performed with temperature-independent and -dependent variations in reaction rates using the REACLIB and STARLIB libraries, respectively. A total of 1,711 (p, γ), (p, α), (α, p), and (α, γ) reactions are varied simultaneously, along with their inverse reactions, via detailed balance. For the first time, it is found that Monte Carlo sampling with larger perturbations to these reaction rates may lead to multi-peaked abundance distributions for some isotopes. These multi-peak structures arise not only from coupled reactions but also, in some cases, from single reactions. Our study also confirmed previously identified key reactions and provides more robust lists. These reactions deserve priority consideration in future study.

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.