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.

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.

Identifying the thermodynamic conditions marking the onset of fission cycling is crucial for modeling heavy-element production in the r-process. In this work, we develop a framework to determine this onset over the (T-9, n(n)) plane. We define a heavy-region condition band near N approximate to 184 and construct an equilibrium path band based on the effective neutron separation energy S-n (0)(T-9,n(n)) . We then compare the lifetimes of neutron-induced fission and beta-decay for nuclei with 94 <= Z <= 106 . Within this framework, we construct a continuous map of actinide nuclei along the equilibrium path band, identifying where neutron-induced fission first overtakes beta-decay. We find that, with increasing temperature and neutron density, the onset shifts toward nuclei with lower proton number (Z) and smaller mass number (A), transitioning from the Es-Cf region to the Am region. These results provide a quantitative benchmark for identifying the conditions under which fission cycling occurs in heavy r-process environments.

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.

A suitable Hamiltonian was designed for the Zr isotopes over the N = 50 shell by including shell model space between Ni-78 and Sn-132. The Hamiltonian is composed by the pairing-plus-multipole force and monopole correction terms. The single-particle energies (SPEs) were initially taken from the low-lying states of hole nuclei In-131 and Sn-131 (near the N = 82 shell closure). These SPEs were then modified by three monopole correction terms to better describe the low-lying states of Zr-91 (near the N = 50 shell closure). To test this Hamiltonian, the level spectra of Zr91-94 were investigated in both low-lying and high-spin excitations by large-scale shell-model calculations. Their wave functions were further tested by comparing the electromagnetic transition probabilities with given data. The good performance in both spectra and transitions probabilities makes the predicting calculations of the present interaction more dependable to be referred in further experimental researches of Zr isotopes.

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.

The L X - L UV relation serves as a cornerstone for extending the Hubble diagram to higher redshift by utilizing quasars as standard candles. However, the constancy of the L X - L UV relation has been embroiled in controversy recently. In this work, we discuss the possible physical origins of evolution in the luminosity relation and provide explicit forms for the redshift and Γ X dependences. By calibrating quasar distances with the baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument Data Release 2 in combination with the cosmic microwave background measurements from Planck, the parameters in different luminosity relations are constrained with a clean quasar sample. Our analysis indicates strongly that the L X - L UV relation varies simultaneously with redshift and Γ X , and this conclusion is robust under the cosmological model assumptions. Furthermore, the dependence on redshift and Γ X implies that the L X - L UV relation is influenced by the properties of accreting supermassive black holes.

The L-X-L-UV relation serves as a cornerstone for extending the Hubble diagram to higher redshift by utilizing quasars as standard candles. However, the constancy of the L-X-L-UV relation has been embroiled in controversy recently. In this work, we discuss the possible physical origins of evolution in the luminosity relation and provide explicit forms for the redshift and Gamma(X) dependences. By calibrating quasar distances with the baryon acoustic oscillation measurements from the Dark Energy Spectroscopic Instrument Data Release 2 in combination with the cosmic microwave background measurements from Planck, the parameters in different luminosity relations are constrained with a clean quasar sample. Our analysis indicates strongly that the L-X-L-UV relation varies simultaneously with redshift and Gamma(X), and this conclusion is robust under the cosmological model assumptions. Furthermore, the dependence on redshift and Gamma(X) implies that the L-X-L-UV relation is influenced by the properties of accreting supermassive black holes.

As a typical “intermediate p-nuclide,” ^112 Sn has a solar system abundance that normal p -process models have long failed to explain adequately, leading to the well-known “p-nuclide abundance problem.” In explosive astrophysical surroundings, due to a relatively low excitation energy of ^113m Sn, the isomer of ^113 Sn ( ^113m Sn, J ^π = 7/2 ^+ , E = 77.4 keV, T _1/2 = 21.4 minutes) and its ground state ( ^113g Sn, J ^π = 1/2 ^+ , T _1/2 = 115.08 days) could reach thermal equilibrium. In this work, we investigate through astrophysical network calculations how the thermalized astromer ^113m Sn impacts the abundance of ^112 Sn in a Type II supernova (SN II) model. The results show that after considering the thermalized ^113m,g Sn effect, the abundance of ^112 Sn increases by 342% (from 1.16 × 10 ^−11 to 5.12 × 10 ^−11 ) at the internal mass coordinate M _r = 2.9461 M _⊙ within the O/Ne burning zone of the 25 M _⊙ SN II model. The appearance of abundance increase also exists in the 15​​​​​​, 20, and 30 M _⊙ SN II models. This indicates that ^113m Sn can significantly affect the astrophysical nucleosynthesis of ^112 Sn. Accordingly, the normalized average overproduction factor 〈 F _i 〉/〈 F _0 〉 of ^112 Sn rises from 0.33 or 0.17 to 0.47. This value enters the accepted uncertainty range (approximately a factor of 3) relative to solar system abundance. We conclude that this study could help resolve the underestimation of ^112 Sn in SN II surroundings and meanwhile provides a new perspective for understanding the nucleosynthesis pathways of intermediate p-nuclei.

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 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.

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.

Neutrino-induced nuclear reactions play a crucial role in astrophysical nucleosynthesis. When a supernova explodes, the neutrino shockwave interacts with the outer material of the star to induce the neutrino-process (nu-process), which is essential for elucidating heavy element synthesis and the exotic abundance distribution of proton-rich nuclei. In this study, the cross sections of neutrino-nucleus reactions are deduced using the nuclear gross theory of beta decay (GTBD). The calculation results of C-12(nu(e),e(-))N-12(g.s)., O-16(nu(e),e(-))F-16, Fe-56(nu(e),e(-))Co-56, and Pb-208(nu(e),e(-))Bi-208 reactions are consistent with those predicted using the QRPA, Hybrid, RPA, and pnQRPA models within an order of magnitude. These results are reasonable given our current knowledge of neutrino-nucleus reactions. Building on this foundation, we propose a semi-empirical parametrization formula that describes the spectrum-weighted cross section of supernova neutrinos as a function of neutrino effective temperature. This formula is instrumental in the development of a convenient database for neutrino-nucleus reaction cross sections. Such a database is anticipated to streamline the process of accessing cross section data, thereby enhancing the efficiency of model calculations based on nuclear astrophysical networks.

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.

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.

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.

The angular distribution of elastic scattering is highly sensitive to the surface region of the nucleus, making it a powerful tool for measuring the neutron skin thickness. Utilizing the CDM3Y6 double-folding potential, we extracted the neutron skin thickness of Sn-124 from the( 12)C + Sn-124 elastic scattering angular distribution, obtaining values of 0.168(-0.019)(+0.025) fm (SLy4) and 0.177 +/- 0.022 fm (SLy7). These results are consistent with measurements from various other methods. Furthermore, through correlation analysis between the neutron skin thickness and nuclear symmetry energy slope parameter L, we determined the symmetry energy slope coefficients to be L=39.0(-16.5)(+20.8 )MeV (SLy4) and L=46.1 +/- 18.7 MeV (SLy7) based on the scattering data. These findings validate existing theoretical models and provide valuable insights for further studies on neutron stars and nuclear matter properties.