Neutron capture on the s-process branch point nucleus ⁶³Ni

The cosmic abundance distribution of elements and isotopes is related to the reaction rates of the different synthesis processes. It is important to know those rates under the different conditions found in the universe to explain the origin of this abundance pattern. Most of the elements heavier than iron have been and still are synthesized in neutron-induced reactions in stars of different stages. Nearly all of the observed abundances are either formed by the s- or the r-process in almost equal shares. Of special interest are branching point nuclei like ⁶³Ni, where the s-process path can take different ways. The neutron capture cross (CS) section of ⁶³Ni affects the abundances of other nuclei in this region. In order to determine the energy dependent neutron capture cross section in the astrophysical energy region (kT_astro ≈ 1⋯ 100 keV), an experiment at the Los Alamos National Laboratory has been performed using the calorimetric 4π BaF ₂ array DANCE. A preliminary result of the ⁶³Ni experiment is presented. The (n,γ) CS of ⁶³Ni has been determined relative to the known ⁶²Ni CS, which was also measured at Los Alamos [1]. Various possible ⁶³Ni resonances have been identified via the Q-value. The contribution of other isotopes in the sample could be identified.