[en] Systematic indirect measurements of nuclear astrophysical reactions using the unstable ion beam facility GIRAFFE in CIAE were performed. We have measured the angular distributions of transfer reactions, such as ⁸Li(d,p)⁹Li, ⁸Li(d,n)⁹Be and ⁸Li(p,d)⁷Li in inverse kinematics, and derived the astrophysical S-factors or reaction rates for ⁸Li(n,γ)⁹Li and ⁸Li(p,γ)⁹Be by using asymptotic normalization coefficient (ANC) or spectroscopic factor methods.

[en] Presented here was current progress of the study of nuclear astrophysical reaction and decay at CIAE. We studied astrophysical ¹²N(p,γ)¹³O reaction through the measurement of the ¹²N(d,n)¹³O angular distribution in inverse kinematics. Our result is in agreement with that from the ¹⁴N(¹²N,¹³O)¹³C reaction and two shell model calculations. We also measured the angular distributions of single neutron transfer reaction of ⁷Li(⁶Li,⁷Li)⁶Li, and derived the reaction cross section for ⁶Li(n,γ)⁷Li by using the present spectroscopic factor. The astrophysical reaction rate is found to be higher by a factor of 1.7 than the value adopted in previous reaction network calculations. In addition, half-life of ¹⁴⁷Sm in metal samarium and Sm₂O₃ was measured. No significant change has been observed within the experimental uncertainty.

[en] We present a new measurement of the α-spectroscopic factor (S_α) and the asymptotic normalization coefficient for the 6.356 MeV 1/2⁺ subthreshold state of ¹⁷O through the ¹³C(¹¹B, ⁷Li)¹⁷O transfer reaction and we determine the α-width of this state. This is believed to have a strong effect on the rate of the ¹³C(α, n)¹⁶O reaction, the main neutron source for slow neutron captures (the s-process) in asymptotic giant branch (AGB) stars. Based on the new width we derive the astrophysical S-factor and the stellar rate of the ¹³C(α, n)¹⁶O reaction. At a temperature of 100 MK, our rate is roughly two times larger than that by Caughlan and Fowler and two times smaller than that recommended by the NACRE compilation. We use the new rate and different rates available in the literature as input in simulations of AGB stars to study their influence on the abundances of selected s-process elements and isotopic ratios. There are no changes in the final results using the different rates for the ¹³C(α, n)¹⁶O reaction when the ¹³C burns completely in radiative conditions. When the ¹³C burns in convective conditions, as in stars of initial mass lower than ∼2 M_☉ and in post-AGB stars, some changes are to be expected, e.g., of up to 25% for Pb in our models. These variations will have to be carefully analyzed when more accurate stellar mixing models and more precise observational constraints are available.

[en] Several reactions have been experimentally studied, including the ¹²N(d,n)¹³O and the ones induced by the ³He+¹²C entrance channel. The former was carried out at the CRIB facility of University of Tokyo, aiming to indirectly determine the astrophysical reaction rates of the ¹²N(p,γ)¹³O reaction. For the ³He+¹²C entrance channel, many excited states of several nuclei are populated and the angular distribution of each state is being analyzed.