Indirect Measurement For The Astrophysical Reaction Rates Of ¹⁵N?p,??¹⁶O Using ?⁷Li,⁶He?

The synthesis of oxygen during the evolution of the universe has always been a concern in the field of nuclear astrophysics.As the basic element of life,the study on the synthesis and abundance of oxygen in the interstellar environment is of great help to explore the origin and evolution of life on earth.It was found that the main pathway of oxygen synthesis in the interstellar environment was the ¹⁵N?p,??¹⁶O reaction in the CNO cycle.In the CNO cycle,the first sub-cycle enters the second sub-cycle through the ¹⁵N?p,??¹⁶O reaction,where the ¹⁵N??,??¹²C reaction competes with the ¹⁵N?p,??¹⁶O reaction.According to the existing research results,the first sub-cycle runs about 2000 times and the second sub-cycle runs once.Although the second sub-cycle makes a small contribution to the energy generation in the CNO cycle,it is of great significance to the subsequent nuclide synthesis such as ¹⁶O andInfluenced by coulomb barrier,interested in astrophysics energy region?p,??reaction cross section is small.At present,the minimum energy directly measured is about 100ke V,which is much different from the astrophysical energy range of interest??23.44ke V?.Therefore,the zero-energy astrophysical S factor of this reaction can only be obtained by extrapolation,and the extrapolation results are generally uncertain.The main contribution of the ¹⁵N?p,??¹⁶O reaction cross section is thethe coherence effect between the direct capture and the two resonances.Usually direct capture is determined by spectroscopic factor extracted from the transfer reaction angle distribution or by the method of asymptotic normalization coefficient?ANC?.At present,the reaction has been studied by several experimental groups using?p,??,?d,n?and?³He,d?.However,there was a several-fold difference between the ¹⁶O proton ANC measured in these groups.Although the zero-energy astrophysical S factor obtained by fitting extrapolation is basically consistent within the error range,the resonance parameters of the two resonant states obtained by fitting are several-fold different.Therefore,it is necessary to adopt the new transfer reaction to make a new indirect measurement of the reaction and to fit the resonance parameters of the two resonant states.In this work,44Me V ⁷Li beam generated by Beijing HI-13 tandem accelerator was used to hit ¹⁵N target,and the elastic scattering angular distribution of¹⁵N?⁷Li,⁷Li?¹⁵N reaction and transfer reaction ¹⁵N?⁷Li,⁶He?¹⁶O reaction was measured on Q3D magnetic spectrograph.By fitting the angle distribution of elastic scatteringincident channel and exit channel are extracted.The proton spectroscopic factor and ANC of the ¹⁶O ground state were obtained by DWBA calculation of the angle distribution of transfer reaction ¹⁵N?⁷Li,⁶He?¹⁶O reaction.Through R matrix analysis of ¹⁵N?p,??¹⁶O direct measurement data,the resonance parameters of ¹⁶O 1^-resonance are obtained,and then the astrophysical S?0?factor at zero energy and astrophysical reaction rate are obtained.At the temperature of stellar hydrogen combustion 0.01?T₉?0.1,the astrophysical reaction rate of our calculation is?0.55 times lower than NACRE.