Radiative neutron capture reaction rates for nucleosynthesis: The creation of the first r-process peak

In neutron star merger events, the occurrence of rapid neutron capture process (r-process) has been established. About half of the elements beyond iron are synthesised in stars by r-process. In stellar environments, very high neutron flux in a short time (similar to a few seconds) can be attained, leading to the creation of progressively neutron-rich nuclei until the waiting point is reached. At this point, further neutron capture reactions cannot happen and highly neutron-rich nuclei become stable via beta(-) decay. A detailed understanding of the r-process remains illusive. In the present work, the theoretical predictions of radiative neutron capture (n,gamma) cross-sections of astrophysical importance and the reaction rates using the Hauser-Feshbach statistical model formalism have been investigated for Fe, Co, Ni, Cu, Zn, Ga, Ge, As and Se isotopes (around the first r-process peak near mass = 80). These calculations have been compared with the JINAREACLIB reaction rates. The inherent uncertainties remain large in neutron-rich nuclei. When there is low-energy enhancement, a significant increase in the reaction rate occurs for neutron capture.