Abstract
The reaction plays a key role in the evolution of stars with masses of . The cross-section of the reaction within the Gamow window () is extremely small (about barn), which makes the direct measurement in a ground-based laboratory with existing techniques unfeasible. Up until now, the cross-sections at lower energies can only be extrapolated from the data at higher energies. However, two subthreshold resonances, located at and , make this extrapolation more complicated. In this work, the 6.917 MeV subthreshold resonance in the reaction was investigated via the reaction. The experiment was performed using the Q3D magnetic spectrograph at the HI-13 tandem accelerator. We measured the angular distribution of the transfer reaction leading to the 6.917 MeV state. Based on the finite-range distorted wave Born approximation (FRDWBA) and coupled-reaction-channel (CRC) analysis, we derived the asymptotic normalization coefficient (ANC) of the 6.917 MeV level in to be () , with which the reduced width was computed to be at the channel radius of 6.5 fm. Finally, we calculated the astrophysical factor of the ground-state transitions to be 46.2 7.7 keV b. The result for the astrophysical factor confirms the values obtained in various direct and indirect measurements and presents an independent examination of the most important data in nuclear astrophysics.
- Received 26 April 2017
- Revised 13 November 2018
DOI:https://doi.org/10.1103/PhysRevC.99.025805
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