Based on the generalized reduced $R$-matrix theory, the $R$-matrix analysis code (RAC) program is employed to analyze all reaction channels associated with the ${}^7\mathrm{Be}$ system. The present calculations provide reliable evaluation data, which shows overall good agreement with available experimental measurements. Benefiting from the multichannel and multienergy fitting procedure, the resulting evaluation is internally self-consistent. The uncertainties of the evaluated cross sections and the covariance matrix are determined using the generalized least-squares method with rigorous uncertainty propagation theory. Compared with existing evaluated nuclear data libraries, the present evaluations are the most comprehensive for the ${}^7\mathrm{Be}$ system, effectively supplementing gaps in current evaluations. For the ${}^6\mathrm{Li}(\mathrm{p},{}^3\mathrm{He}){}^4\mathrm{He}$ reaction, the RAC analysis indicates that the resonance at $E_p \approx 1.8\mathrm{MeV}$ is predominantly associated with the $5/2^{-}$ state of ${}^7\mathrm{Be}$ compound nucleus. In addition, the astrophysical $S$ factor for the ${}^3\mathrm{He}({}^4\mathrm{He},\gamma ){}^7\mathrm{Be}$ reaction is calculated based on the present evaluation and the $S_{34}\left(0\right)$ is determined as $0.{563}_{-0.022}^{+0.022}\mathrm{keV}\mathrm{b}$ . These results are significant for future updates of evaluated nuclear data libraries and have important implications for nuclear astrophysics and the nucleosynthesis studies. The present analysis also highlights the limitations of existing experimental data for the ${}^7\mathrm{Be}$ system and the need for further high-precision measurements.

Close

PrevNext

View figure in article

• Nuclear astrophysics
• Nuclear reactions
• Nuclear structure & decays
• 6 ≤ A ≤ 19