Impact of nuclear level density and γ-ray strength function in (n,γ) and Maxwellian-averaged cross-section of ⁶⁹Zn nucleus

Abstract The present paper highlights the impact of nuclear level density (NLD) and γ-ray strength function (γ-SF) on (n,γ) and Maxwellian-averaged cross-section of 69Zn nucleus. At first, the existing NLD and γ-SF models (in TALYS statistical model code) have been utilized to understand the role of NLD and γ-SF in neutron capture reaction cross-section. It is seen that most of the combinations of existing NLDs and γ-SFs (phenomenological and/or microscopic) cannot explain the experimental data. Therefore, the microscopic EP+IPM (exact pairing plus independent particle model) and EP+PDM (exact pairing plus phonon damping model) have been carried
out to calculate the NLD and γ-SF of 69Zn nucleus, respectively, by employing the exact treatment of thermal pairing. It is seen that microscopic EP+IPM NLD and EP+PDM γ-SF explain the experimental data better than other combinations, indicating the impact of exact treatment of thermal pairing correlation. In addition, the inclusion of an up-bend (UB) structure in γ-SF further improves the comparison with the experimental data in the low energy region (∼ 0.01-0.15 MeV), indicating the possibility of having an UB structure in γ-SF of 69Zn. The 68Zn(n,γ)69Zn reaction cross-section obtained by utilizing the EP+IPM NLD and EP+PDM γ-SF including
UB structure is then used to predict the Maxwellian-averaged cross-sections, and the obtained results show reasonable agreement with all the available experimental data taken from the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars. The present results reflect the impact of microscopic NLD and γ-SF on the precise description and/or prediction of the astrophysical reaction cross-section.