The Moon provides a unique environment for investigating nearby astrophysical events such as supernovae. Lunar samples retain valuable information from these events, via detectable long-lived “fingerprint” radionuclides such as ^60Fe . In this work, we stepped up the development of an accelerator mass spectrometry (AMS) method for detecting ^60Fe using the HI-13 tandem accelerator at the China Institute of Atomic Energy (CIAE). Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph, a Wien filter with a maximum voltage of ± 60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide ^60Fe . A 1 m thick Si _3 N _4 foil was installed in front of the Q3D as an energy degrader. For particle detection, a multi-anode gas ionization chamber was mounted at the center of the focal plane of the spectrograph. Finally, an ^60Fe sample with an abundance of 1.125 × 10^-10 was used to test the new AMS system. These results indicate that ^60Fe can be clearly distinguished from the isobar ^60Ni . The sensitivity was assessed to be better than 4.3 × 10^-14 based on blank sample measurements lasting 5.8 h, and the sensitivity could, in principle, be expected to be approximately 2.5 × 10^-15 when the data were accumulated for 100 h, which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.

The ^{13}C(α,n)^{16}O reaction is the main neutron source for the slow-neutron-capture process in asymptotic giant branch stars and for the intermediate process. Direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray-induced background. We performed the first consistent direct measurement in the range of E_{c.m.}=0.24 to 1.9 MeV using the accelerators at the China Jinping Underground Laboratory and Sichuan University. Our measurement covers almost the entire intermediate process Gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing datasets, and provides a more reliable reaction rate for the studies of the slow-neutron-capture and intermediate processes along with the first direct determination of the alpha strength for the near-threshold state.

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 14 C（n,γ） 15 C reaction plays an important role in various astrophysical scenarios:（1） it is the slowest in the neutron induced CNO cycle which occurs in asymptotic giant branch（AGB） stars, and therefore controls this cycle [1];（2） it is one of the key reactions for predicting the primordial abundances of the heavy elements in the framework of inhomogeneous big-bang nucleosynthesis （IBBN）[2];（3） it is also important for the synthesis of heavier isotopes in neutrino driven wind

长寿命放射性核素26Al是星际介质、γ射线天文学和太阳系形成研究中最重要的核素之一.最可能合成26Al的三种天体场所都与25Mg(p,γ)26Al反应相关,因此精确测量其近阈能级的共振强度和天体物理反应率对人们认识宇宙26Al的来源具有重要意义.本文回顾了25Mg(p,γ)26Al反应的实验研究方法和最新研究进展,特别是介绍了我国对该反应的间接测量实验以及直接实验测量计划.当前的间接测量结果提升了25Mg(p,γ)26Al天体物理反应率的精度,也可以帮助我们估算直接测量的产额,并优化深地直接测量的实验设计.高能点的直接测量结果与国际上其它实验结果在误差范围内符合很好,表明本项目研制的探测装置工作状态良好,能够胜任锦屏深地核天体物理实验研究.

$^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ is the most important reaction in the Mg-Al cycle in the hydrogen burning regions of stars. Its cross sections at stellar energies are essential to understand the issues of radioactive $^{26}\mathrm{Al}$ in the galaxy and meteorites. The 57.7 keV resonance dominate the $^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ astrophysical reaction rates at relative low temperature, but it is very difficult to measure its resonance strength directly, and the indirect measurement results deviate by a factor of about 2 by far. In this work, the angular distributions of $^{25}\mathrm{Mg}(^{7}\mathrm{Li},^{6}\mathrm{He})^{26}\mathrm{Al}$ leading to 6.364 MeV and eleven low-lying states in $^{26}\mathrm{Al}$ have been measured by the Q3D magnetic spectrometer of the HI-13 tandem accelerator. The spectroscopic factors were derived and used to deduce the proton width and 57.7 keV resonance strength. The astrophysical $^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ reaction rates at stellar energies have been updated by using the present result.

>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.

Based on the accurate macroscopic-microscopic mass formula and the experimental data of β -decay half-lives of the nuclei with atomic number ranging from 20 to 190, a systematic formula has been proposed to calculate β -decay half-lives of neutron-rich nuclei. The formula is proved to reproduce the experimental β -decay half-lives of neutron-rich nuclei very well, and then is used to study the r-process nucleosynthesis in models of high-entropy mass outflows. The calculated abundances show a good agreement with the solar r-abundances around the third peak and the rare earth mass region.

The `lithium problem' in Big Bang Nucleosynthesis (BBN) has recently focused on the reactions involving $^7$Be. The $^6$Li($p, \gamma$)$^7$Be reaction can provide us not only the information for destroying $^6$Li but also the information for producing $^7$Be. In the present work, the proton spectroscopic factor in $^7$Be was extracted to be 0.70 $\pm$ 0.17 from the angular distribution of $^7$Be($d$, $^3$He)$^6$Li at $E_\mathrm{c.m.}$ = 6.7 MeV. The value was then used to compute the direct component of the astrophysical $^6$Li($p, \gamma$)$^7$Be$_\mathrm{g.s.}$ S(E) factors and determine the resonance parameters from the total S(E) factors.

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