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.

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.

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.

Calcium production and the stellar evolution of first-generation stars remain fascinating mysteries in astrophysics. As one possible nucleosynthesis scenario, break-out from the hot carbon–nitrogen–oxygen (HCNO) cycle was thought to be the source of the calcium observed in these oldest stars. However, according to the stellar modeling, a nearly tenfold increase in the thermonuclear rate ratio of the break-out ^19 F(p, γ ) ^20 Ne reaction with respect to the competing ^19 F(p, α ) ^16 O back-processing reaction is required to reproduce the observed calcium abundance. We performed a direct measurement of this break-out reaction at the China Jinping underground laboratory. The measurement was performed down to the low-energy limit of E_c.m. = 186 keV in the center-of-mass frame. The key resonance was observed at 225.2 keV for the first time. At a temperature of approximately 0.1 GK, this new resonance enhanced the thermonuclear ^19 F(p, γ ) ^20 Ne rate by up to a factor of ≈ 7.4, compared with the previously recommended NACRE rate. This is of particular interest to the study of the evolution of the first stars and implies a stronger breakdown in their “warm” CNO cycle through the ^19 F(p, γ ) ^20 Ne reaction than previously envisioned. This break-out resulted in the production of the calcium observed in the oldest stars, enhancing our understanding of the evolution of the first stars.

The neutron capture measurement of natural rhenium was performed with the time -of -flight technique at the Back -n facility of the China Spallation Neutron Source in the energy range from 1 to 500 eV of the resolved resonance region (RRR) and from 5 to 400 keV in the unresolved resonance region (URR). Prompt gamma-rays originating from neutron -induced capture events were detected by four C6D6 detectors. The pulse height weighting technique and the double -bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background subtraction, normalization, and corrections were carefully considered. The multilevel R -matrix Bayesian code SAMMY was used to extract the resonance parameters in the RRR. An absence of resonance near 392 eV is observed in our measurement, which has been observed in previous works. The average cross sections in the URR of natural rhenium relative to 197Au were obtained in logarithmical equidistant energy bins with 20 bins per energy decade. The TALYS code was used to describe the average cross sections in the URR; the Maxwellian-averaged cross sections (MACSs) of 185Re and 187Re are given from kT = 5 to 100 keV. At a thermal energy of kT = 30 keV, the MACS value for 185Re (1469 +/- 127 mb) is in good agreement with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNIS) recommended value (1535 +/- 62 mb) within the error bars. By contrast, the value of 1361 +/- 118 mb for 187Re shows a discrepancy with the KADONIS recommended value (1160 +/- 57 mb).

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.

In nuclear astrophysics, 141Pr is mainly produced by an s process, which has a neutron magic number (N = 82) leading to its low capture cross section and strongly affecting the s process. Its neutron capture cross section is an important input parameter for nuclear astrophysical network calculations. According to the EXFOR database, the measurement precision for the 141Pr(n, gamma) cross section should be improved in the resolved and unresolved reso-nance region. The (n, gamma) cross section of 141Pr was measured between 1 eV and 500 keV at the Back-n facility of the Chinese Spallation Neutron Source using the time-of-flight (TOF) method. The prompt gamma rays were detected by four C6D6 liquid scintillator detectors, and the data was analyzed using the pulse-height weighting technique (PHWT). The majority of results are in agreement with the evaluated data libraries ENDF/B-VIII.0, JENDL-5.0, and TENDL-2021, with some significant exceptions for small resonances. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters of 141Pr in the resolved resonance region. And the Maxwell average cross section (MACS) from kT = 5 to 100 keV is calculated in the temperature range of the s-process nucleosynthesis model. In particular, at kT = 30 keV the MACS value of 141Pr is 145.0 +/- 13.7 mb, which shows an obvious discrepancy with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) recommended value 111.4 +/- 1.4 mb.

Proposed mechanisms for the production of calcium in the first stars (population III stars)—primordial stars that formed out of the matter of the Big Bang—are at odds with observations1. Advanced nuclear burning and supernovae were thought to be the dominant source of the calcium production seen in all stars2. Here we suggest a qualitatively different path to calcium production through breakout from the 'warm' carbon–nitrogen–oxygen (CNO) cycle through a direct experimental measurement of the 19F(p, γ)20Ne breakout reaction down to a very low energy point of 186 kiloelectronvolts, reporting a key resonance at 225 kiloelectronvolts. In the domain of astrophysical interest2, at around 0.1 gigakelvin, this thermonuclear 19F(p, γ)20Ne rate is up to a factor of 7.4 larger than the previous recommended rate3. Our stellar models show a stronger breakout during stellar hydrogen burning than previously thought1,4,5, and may reveal the nature of calcium production in population III stars imprinted on the oldest known ultra-iron-poor star, SMSS0313-67086. Our experimental result was obtained in the China JinPing Underground Laboratory7, which offers an environment with an extremely low cosmic-ray-induced background8. Our rate showcases the effect that faint population III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, which are key mission targets of the James Webb Space Telescope9. Observation of a new resonance in the 19-fluorine to 20-neon thermonuclear reaction at the China JinPing Underground Laboratory (over 2 km below ground) may provide clues to observed discrepancies in calcium production in the evolution of the first stars.

The cosmic 1.809 MeV γ-ray emitted by the radioactive nucleus 26Al in the Galaxy is one of the key observation targets of the γ-ray astronomy. The 26Al is mainly produced by the 25Mg(p,γ)26Al reaction in the stellar Mg-Al reaction cycle. At the astrophysical relevant temperatures, the reaction rates of 25Mg(p,γ)26Al are dominated by several narrow resonances at low energy. This work reports a measurement of the low energy 25Mg(p,γ)26Al resonances at Jinping Underground Nuclear Astrophysics experimental facility (JUNA) in the China Jinping Underground Laboratory (CJPL).

In nuclear astrophysics, the nuclides ^151 Eu and ^153 Eu are both in the path of the s-process, and their (n, γ ) cross sections are important input parameters for the calculation of the nuclear astrophysics network. According to the EXFOR database, the neutron capture cross section of natural europium in the resonance region has not been fully measured. The (n, γ ) cross section of ^nat Eu was measured using the time-of-flight (TOF) technique at the Back-n white neutron source facility of the China Spallation Neutron Source (CSNS) in the 1 eV–to 500 keV range. Four C _6 D _6 liquid scintillator detectors and pulse height weighting techniques were used to measure prompt γ rays and analyze the data. The results of the analysis were compared with the evaluated data of ENDF/B-VIII.0 and JENDL-5.0. It shows that there are some differences between the measurement results and different evaluated data libraries. The resonance parameters of ^151 Eu and ^153 Eu were extracted in the 1 eV–150 eV region using the R-Matrix code SAMMY. The accurate Maxwellian-averaged capture cross section (MACS) is derived over the temperature range of the s-process nucleosynthesis model. The result shows that at kT=30 keV, the MACS value of ^151 Eu is 3417 ± 297 mb and the value of ^153 Eu is 2718 ± 237 mb.

Underground Nuclear Astrophysics Experiment in China (JUNA) has been commissioned by taking the advantage of the ultra-low background in Jinping underground lab. High current mA level 400 KV accelerator with an ECR source and BGO detectors were commissioned. JUNA studies directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. In the first quarter of 2021, JUNA performed the direct measurements of 25Mg(p,γ)26Al, 19F(p,α)16O, 13C(α,n)16O and 12C(α,γ)16O near the Gamow window. The experimental results reflect the potential of JUNA with higher statistics, precision and sensitivity of the data. The preliminary results of JUNA experiment and future plan are given.

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 cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and of this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging. Due to their radioactive lifetime of million years, the 26Al and 60Fe isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of 26Al and 60Fe, the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. We connect the theoretical astrophysical aspects to the variety of astronomical messengers, from stardust and cosmic-ray composition measurements, through observation of gamma rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of 26Al to 60Fe eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution.

Experimental elastic scattering angular distributions of B-11, C-12, and O-16 + heavy-ions are used to study the Woods-Saxon potential parameters. Best fitted values of the diffuseness parameters are found for each system, and a linear relationship is expressed between the diffuseness parameters and A(1)(1/3) + A(2)(1/3). The correlation of the potential depth and radius parameters with A(1)(1/3) + A(2)(1/3) is also revealed within the limitations of the diffuseness parameter formula. Because the incident energies of most of the analyzed reactions are below or around the Coulomb barrier, the energy dispersion relation between the real and imaginary potentials is considered in order to investigate the ratio between the imaginary and real potential well depths, resulting in an expression of W/V. Within the limitation of the volume integrals calculated with the Sao Paulo potential, parameterized formulas for the depth and radius parameters are obtained. The systematic Woods-Saxon potential parameters derived in the present work can reproduce not only the experimental data of elastic scattering angular distributions induced by B-11, C-12, and O-16 but also some elastic scattering induced by other heavy-ions.

16F是质子滴线附近的奇特原子核,它的所有态均不稳定,会发生质子衰变.目前16F前4个态的自旋宇称及激发能已通过实验精确测定,但能级宽度仍存在较大分歧.本工作通过15N(d,p)16N反应角分布的高精度测量,确定了 16N基态和前3个激发态的谱因子;进而根据镜像核的电荷对称性,用16N的中子谱因子导出了 16F基态和前3 个激发态的质子宽度分别为(29.9±4.1)keV、(108±13)keV、(5.04±0.48)keV和(14.5±1.4)keV.本工作通过一个独立的实验方法为16F的质子宽度提供了一个重要的交叉检验.

>Spectroscopic factor elucidates the overlap between the initial and final states as well as the occupancy of a given singleparticle orbit. It plays an important role in nuclear reactions and nuclear astrophysics. Single-nucleon transfer reactions such as (d, p) and (d, n) have been used extensively to extract the spectroscopic information of the single-nucleon orbits in nuclei located at or near the stability line [1-3], by comparing

The ’lithium problem, in Big Bang nucleosynthesis（BBN） has recently focused on reactions involving ~7 Be.The ~6 Li（p,γ）~7 Be reaction can provide us not only with information about ~6 Li destruction but also with information about ~7 Be production. In the present work, the proton spectroscopic factor in ~7 Be is extracted to be 0.70 ± 0.17 from the angular distribution of ~7 Be（d, ~3 He）~6 Li at E c.m. = 6.7 MeV. This value is then used to compute the direct component of the astrophysical ~6 Li（p,γ）~7 Be g.s. S（E） factors and determine the resonance parameters from the total S（E） factors.

In the standard Big Bang nucleosynthesis（SBBN） model, the lithium puzzle has attracted intense interest over the past few decades, but still has not been solved. Conventionally, the approach is to include more reactions flowing into or out of lithium, and study the potential effects of those reactions which were not previously considered.~7Be（d,~3He）~6Li is a reaction that not only produces~6Li but also destroys~7Be, which decays to~7Li, thereby affecting~7Li indirectly. Therefore, this reaction could alleviate the lithium discrepancy if its reaction rate is sufficiently high.However, there is not much information available about the~7Be（d,~3He）~6Li reaction rate. In this work, the angular distributions of the~7Be（d,~3He）~6Li reaction are measured at the center of mass energies Ecm = 4.0 Me V and 6.~7Me V with secondary~7Be beams for the first time. The excitation function of the~7Be（d,~3He）~6Li reaction is first calculated with the computer code TALYS and then normalized to the experimental data, then its reaction rate is deduced. A SBBN network calculation is performed to investigate its influence on the~6Li and~7Li abundances. The results show that the~7Be（d,~3He）~6Li reaction has a minimal effect on~6Li and~7Li because of its small reaction rate. Therefore,the~7Be（d,~3He）~6Li reaction is ruled out by this experiment as a means of alleviating the lithium discrepancy.