Yuwen Chen

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.

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.