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.

Accurate reconstruction of the target atom depth distribution is essential for reliable nuclear reaction measurements. We present a comprehensive method to extract the depth distribution of target atoms from measured resonance yield curves by coupling an iterative non-linear Geant4-based transport model with the Bayesian Analysis Toolkit (BAT). Unlike previous linearized deconvolutions developed for trace-element ion beam analysis (IBA), the present framework is tailored to high-concentration targets typical of nuclear astrophysics experiments, and complements the existing IBA approach. As an example, the 19F depth distribution of two implanted targets has been reconstructed with quantified uncertainties by analyzing the resonance yield curves of the 19F(p, ay)16O reaction, which demonstrates the analysis power of this target diagnostics method.

The photodisintegration cross sections of the deuteron have been systematically measured over the photon energy range of 2.33-19.65 MeV at the Shanghai Laser Electron Gamma Source. By applying the well-established Baldin sum rule to the newly obtained data, the sum of the electric and magnetic dipole polarizabilities of the deuteron is extracted for the first time based solely on a dense and continuous experimental dataset, yielding α_{E}+β_{M}=0.719±0.009_{stat}±0.014_{algo}±0.023_{syst}  fm^{3}. With theoretical values of the magnetic polarizability β_{M} calculated from the pionless effective field theory, a new value of the electric polarizability is obtained as α_{E}=0.637±0.009_{stat}±0.014_{algo}±0.023_{syst}±0.004_{theo}  fm^{3}, which is in excellent agreement with current theoretical predictions. This result resolves the previous discrepancy between experimental measurements from elastic scattering and theory, providing a high-precision benchmark for nuclear interaction models.

The 14N(p,1)15O reaction plays a crucial role in studies of hydrogen burning. Irradiation-resistant nitride targets are essential for extending direct measurements of this reaction to lower energies. In this work, we fabricated nitride targets using filter cathodic vacuum arc (FCVA) and low-pressure chemical vapor deposition (LPCVD) techniques. The thickness and chemical composition of the targets, as well as the impurity levels of the TiN targets, were evaluated through corresponding reaction measurements. The results indicate that FCVAfabricated TiN targets exhibit the best comprehensive performance. The deterioration of the TiN targets under the bombardment of a similar to 2 mA proton beam was investigated by monitoring the yield curves. The reduction rates of the atomic areal density for these targets were found to be in the range of 0.084-0.16%/C. The prepared TiN targets successfully advanced the measurement of 14N(p,1)15O reaction to Ep = 110 keV in a ground laboratory, which will enable further extension to Ep = 70 keV at the Jinping Underground Nuclear Astrophysics facility (JUNA) in the future.

This work provides an overview of the origin of the p-nuclei in the cosmos, problems with p-process models, as well as possible solutions on the nuclear physics aspect. The Shanghai Laser Electron Gamma Source (SLEGS) based on Shanghai Light Source is the first experimental facility capable of generating quasi-monoenergetic gamma-ray beams in China. SLEGS can provide the unique experimental conditions for photonuclear reaction measurements. Based on the established detection systems for measuring various types of outgoing particles, this paper lists a series of photonuclear reaction experiments of p-process importance to be carried out. Such experimental studies will effectively constrain the theoretical statistical model of nuclear reactions, and provide reliable nuclear-physics inputs for understanding the origin of the rarest nuclides 180Tam and138La in the solar system, as well as the underproduction problem of p-nuclei, such as Mo and Ru.

Directly measuring key nuclear reactions within the Gamow window of stars is a critical frontier in modern nuclear astrophysics. The China Jinping Underground Laboratory (CJPL) offers an ultra-low-background environment, serving as the foundation for the China Jinping deep Underground Nuclear Astrophysics experimental platform (JUNA). By utilizing JUNA's high-intensity accelerator, efficient detectors, and advanced targets, several crucial nuclear reactions relevant to stellar evolution have been successfully measured within the energy ranges of relevant stars. These reactions include Mg-25(p,gamma)Al-26, F-19(p, alpha)O-16, C-13(alpha, n)O-16, and C-12(alpha, gamma)O-16, significantly enhancing our understanding of heavy element production in early and massive stars. The JUNA experiment has achieved internationally advanced levels in data statistics, measurement precision, and sensitivity. This article will summarize JUNA's key experimental results and compare them with current international advancements to highlight the platform's unique strengths. Additionally, it will offer an outlook on the future development of JUNA Run-2.

The precise determination of cross sections for key nuclear reactions within the Gamow window is crucial for advancing the study of stellar evolution and nucleosynthesis. However, extremely low reaction yields combined with the cosmic-ray-induced background make these measurements highly challenging, particularly for capture reactions. This work demonstrates the second configuration of the large-scale modular BGO detection array (LAMBDA-II) designed to capture reaction measurements and introduces a method for suppressing γ -ray detection background in ground laboratories. By employing active and passive shielding, the background of LAMBDA-II was significantly reduced by approximately two orders of magnitude, reaching 8.1×10^-3 and 1.0×10^-3 keV^-1h^-1 in the 6–11 and 11–20 MeV energy ranges, respectively. When combined with a mA-scale intensity beam, this reduced background enables the investigation of several capture reactions of astrophysical interest in ground laboratories.

This article reviews the development and achievements of the Jinping Underground Nuclear Astrophysics (JUNA) experimental platform and focuses on the direct measurement of reaction rates within or near the Gamow window in deep-underground astrophysical experiments. It discusses the advantages of conducting experiments in the deep-underground environment of the China Jinping Underground Laboratory (CJPL), which provides significant shielding from cosmic rays along with milliampere-level intensity from the JUNA accelerator. This shielding and the high beam intensity are crucial for accurately measuring very-low-cross-section nuclear reactions essential to understanding astrophysical processes, such as the synthesis of heavy elements in stars from neutron sources and CNO cycle leakage. The manuscript also covers technological achievements, including advancements in ion sources, accelerators, detectors, and targets used in the JUNA experiment. The physics results from these experiments provide valuable data for key reactions, such as neutron source reactions and radiative capture reactions, as well as for the production of heavy elements in early stars. Future plans for the JUNA experiment are also outlined.

^147,149Sm are slow neutron capture (s-process) nuclides in nuclear astrophysics, whose (n, γ ) cross sections are important input parameters in nucleosynthesis network calculations in the samarium (Sm) region. In addition, ^149Sm is a fission product of ^235U with a 1 ^147,149Sm (n, γ ) cross-sectional data within the energy range of 20–300 eV. In this study, tutron capture cross section of a natural samarium target was measured at the back-streaming white neutron beamline of the China Spallation Neutron Source. The neutron capture yield was obtained, and the neutron resonance parameters for ^147Sm at 107.0, 139.4, 241.7, and 257.3 eV and ^149Sm at 23.2, 24.6, 26.1, 28.0, 51.5, 75.2, 90.9, 125.3, and 248.4 eV were extracted using the SAMMY code based on R-matrix theory. For the parameters Γ _n and Γ _γ in these energies of ^147,149Sm , the percentages consistent with the results of the CENDL-3.2, ENDF/B-VIII.0, JEFF-3.3, JENDL-4.0, and BROND-3.1 database are 27 ^147,149Sm neutron capture resonance and helps clarify the differences between different evaluation databases at the above energies.

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.

KV Vel is a noneclipsing short-period (P = 0.3571 days) close binary containing a very hot subdwarf primary (77,000 K) and a cool low-mass secondary star (3400 K) that is located at the center of the planetary nebula DS 1. The changes in the orbital period of the close binary were analyzed based on 262 new times of light maximum together with those compiled from the literature. It is discovered that the O - C curve shows a small-amplitude (0.(d)0034) cyclic period variation with a period of 29.55 yr. The explanation by the solar-type magnetic activity cycles of the cool component is ruled out because the required energies are much larger than the total radiant energy of this component in a whole cycle. Therefore, the cyclic variation was plausibly explained as the light-travel time effect via the presence of a tertiary component, which is supported by the periodic changes of the O - C curve and the rather symmetric and stable light curves obtained by the Transiting Exoplanet Survey Satellite. The mass of the tertiary companion is determined to be M-3 sini '=0.060(+/- 0.007) M-circle dot. If the third body is coplanar with the central binary (i.e., i '=62.degrees 5 ), the mass of the tertiary component is computed as M-3 similar to 0.068 M-circle dot, and thus it would be below the stable hydrogen-burning limit and is a brown dwarf. The orbital separation is shorter than 9.35 au. KV Vel together with its surrounding planetary nebula and the brown-dwarf companion may be formed through the common-envelope evolution after the primary filled its Roche lobe during the early asymptotic giant branch stage.

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.

Big Bang nucleosynthesis (BBN) theory predicts the primordial abundances of the light elements ^2 H (referred to as deuterium, or D for short), ^3 He, ^4 He, and ^7 Li produced in the early universe. Among these, deuterium, the first nuclide produced by BBN, is a key primordial material for subsequent reactions. To date, the uncertainty in predicted deuterium abundance (D/H) remains larger than the observational precision. In this study, the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium abundance. We found that the reaction rate uncertainties of the four reactions d(d,n) ^3 He, d(d,p)t, d(p,γ )^3 He, and p(n,γ)d had the largest influence on the calculated D/H uncertainty. Currently, the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^3 He rate. From the nuclear physics aspect, there is still room to largely reduce the reaction-rate uncertainties; hence, further measurements of the important reactions involved in BBN are still necessary. A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ )d .

In thermonuclear reactions of nuclear astrophysical interest,some can produce short-lived products that emit positrons.These positrons will annihilate with electrons in the target and then produce a pair of 511 keV γ-rays,which can be used to determine the reaction yield and calculate the cross-section as well as the astrophysical S-factor.Recently,an in situ measurement method for positron annihilation on experimental terminals has been proposed.This method takes advantage of the characteristic opposite direction of the 511 keV γ-ray pairs and uses the opposite units in the detection array for spatial co-incidence measurements to suppress background.In this study,we investigated this method using the newly developed large modular BGO detector array LAMBDA-Ⅱ.The results show that the detection efficiency of LAMBDA-Ⅱ for in situ β+decay of reaction products is(7.6±0.2)％,which is in good agreement with the value given by Monte Carlo simulations.The yield of the 14N(p,γ)15O 259 keV resonance determined by in situ measurement agrees well with that derived from prompt γ-ray meas-urement,verifying the reliability of this method and providing a solid foundation for its further application in nuclear astro-physics research.

22Na(p,γ)23Mg and 19Ne(α,p)22Na are two crucial reactions in the so-called NeNa-MgAl cycle and the rapid-pro-ton process,their astrophysical reaction rates are indispensable inputs in understanding the outburst mechanism and element synthesis of novae.Since many proton resonance levels in odd-A compound nucleus 23Mg may be involved at nova temperat-ure,existing measurements can only provide partial effective information on the 22Na(p,γ)23Mg reaction,large discrepancies still exist in the astrophysical reaction rates of the two reactions.In the present work,22Na+p resonance scattering via thick target inverse kinematics was studied at RIBLL1 radioactive beam line in the HIRFL national laboratory at Lanzhou.Excita-tion functions of 22Na(p,p)are obtained in the energy range of Ec.m.=1.5 to 4 MeV.Obvious resonance structure is observed in the 23Mg compound nucleus,resonance parameters are deduced for 22 proton resonance states in 23Mg via R-matrix analys-is,which will be used for the evaluation of the astrophysical reaction rates of 22Na(p,γ)23Mg and 19Ne(α,p)22Na.

This report presents experimental differential cross section measurements at α0-particles' eight outgoing angles of 50o, 70o, 90o, 106o, 120o, 130o, 150o, and 160o from 11B(p, α0)8Be reaction induced by 2.5 MeV proton beam bombarding on a natural boron target. The proton beams were accelerated by the 5SDH-2 pelletron at the University of Science - Hanoi National University (HUS). A good agreement has been observed between the obtained results and those from the literature. The importance of the data in a widely angular range is evidenced for the precise determination of the total integrated cross section.

Total absorption gamma-ray spectroscopy (TAGS) is a powerful tool for measuring complex γ transitions, which has been effectively applied to the study of reactor decay heat. This paper presents the design of a new TAGS detector, the large-scale modular BGO detection array (LAMBDA), tailored for measuring β -decay intensity distributions of fission products. The modular design allows the LAMBDA detectors to be assembled in various configurations. The final version of LAMBDA consists of 102 identical 60 mm × 60 mm × 120 mm BGO crystals and exhibits a high full-energy peak efficiency exceeding 80 ∼ 8 MeV based on a Monte Carlo simulation. Currently, approximately half of the LAMBDA modules have been manufactured. Tests using γ -ray sources and nuclear reactions demonstrated favorable energy resolution, energy linearity, and efficiency uniformity across the modules. Forty-eight modules have been integrated into the prototype LAMBDA-I. The capability of LAMBDA-I in β -delayed γ -decay experiments was evaluated by commissioning measurements using the ^152 Eu source.

This paper introduces a new platform established for nuclear astrophysics studies on Hefei Facility in China. Currently, the high-voltage accelerator can deliver a proton beam with current up to approximately 5 mA in the energy range of & SIM;50-350 keV. The proton beam energy and its spread were calibrated with two resonant reactions, and satisfy the experimental beam requirements for nuclear astrophysics studies. At the 90 degrees beamline of this platform, we have installed a new setup (including target chamber, cold trap, silicon detectors, preamplifiers and DAQ), which is specifically designed for charged-particle measurements. Based on a careful background study of the target chamber, the charged-particle measurement of the19F(p, ⠋0)16O reaction can be performed down to the low-energy region of astrophysical interest with this setup. Some other astrophysical experiments are also prospected.

26Al with a half-life of 7.17x105 years is one of the most significant nuclides in & gamma;-ray astronomy and presolar grains of meteorites. Its main production mechanism in the H-burning MgAl cycle is the 25Mg(p, & gamma;)26Al reaction. In the temperature region of 0.05-0.3 GK of astrophysical interest, the astrophysical 25Mg(p, & gamma;) 26Al reaction rate is dominated by the resonant capture of several low-energy resonances. In this work, we report the results of a complete experimental investigation of the Ec.m. = 92, 130, and 189 keV resonances in the 25Mg(p , & gamma;)26Al reaction with the Jinping Underground Nuclear Astrophysics Experimental Facility. The up-dated thermonuclear 25Mg(p, & gamma; ) 26Al reaction rate is (32-39)% higher than that obtained at the Laboratory for Underground Nuclear Astrophysics around 0.07-0.09 GK, mainly due to the 32% enhancement of the 92-keV resonance strength. The astrophysical impact of our new rate on the 26Al yield in a 5 Mo low-metallicity asymptotic giant branch star is investigated, in which an increase of (45-79)% in the 26Al yield is found by adopting our new 25Mg(p, & gamma; ) 26Al rates.

X-ray bursts are among the brightest stellar objects frequently observed in the sky by space-based telescopes. A type-I X-ray burst is understood as a violent thermonuclear explosion on the surface of a neutron star, accreting matter from a companion star in a binary system. The bursts are powered by a nuclear reaction sequence known as the rapid proton capture process (rp process), which involves hundreds of exotic neutron-deficient nuclides. At so-called waiting-point nuclides, the process stalls until a slower β + decay enables a bypass. One of the handful of rp process waiting-point nuclides is 64 Ge, which plays a decisive role in matter flow and therefore the produced X-ray flux. Here we report precision measurements of the masses of 63 Ge, 64,65 As and 66,67 Se—the relevant nuclear masses around the waiting-point 64 Ge—and use them as inputs for X-ray burst model calculations. We obtain the X-ray burst light curve to constrain the neutron-star compactness, and suggest that the distance to the X-ray burster GS 1826–24 needs to be increased by about 6.5% to match astronomical observations. The nucleosynthesis results affect the thermal structure of accreting neutron stars, which will subsequently modify the calculations of associated observables.