Statistical γ -decay properties of Ni 64 and deduced (n,γ) cross section of the s -process branch-point nucleus Ni 63

Particle-γ coincidence data have been analyzed to obtain the nuclear level density and the γ-strength function of Ni64 by means of the Oslo method. The level density found in this work is in very good agreement with known energy levels at low excitation energies as well as with data deduced from particle-evaporation measurements at excitation energies above Ex≈5.5 MeV. The experimental γ-strength function presents an enhancement at γ energies below Eγ≈3 MeV and possibly a resonancelike structure centered at Eγ≈9.2 MeV. The obtained nuclear level density and γ-strength function have been used to estimate the (n,γ) cross section for the s-process branch-point nucleus Ni63, of particular interest for astrophysical calculations of elemental abundances. © 2016 American Physical Society