Nuclear level density of 69Zn from gamma gated particle spectrum and its implication on 68Zn(n, γ)69Zn capture cross-section
Abstract
Evaporated α-spectra have been measured in coincidence with low energy discrete γ-rays from residual nucleus 68Zn populated in the reaction 64Ni(9Be,αn)68Zn at E(9Be) = 30 MeV producing 73Ge compound nucleus. Low energy γ-gated α-particle spectra, for the first time, have been used to extract the nuclear level density (NLD) for the intermediate 69Zn nucleus in the excitation energy range of E ≈ 5-20 MeV. The slope of NLD as a function of excitation energy for 69Zn matches nicely with the slope determined from RIPL estimates for NLD at low energies and the NLD from neutron resonance data. Extracted inverse NLD parameter (k = A/a) has been used to determine the nuclear level density parameter value a at neutron separation energy Sn for 69Zn. Total cross-section of 68Zn(n,γ) capture reaction as a function of neutron energy is then estimated employing the derived a(Sn) in the reaction code TALYS. It is found that the estimated neutron capture cross-section agrees well with the available experimental data without any normalization. The present result indicates that experimentally derived nuclear level density parameter can constrain the statistical model description of astrophysical capture cross-section and optimize the uncertainties associated with the astrophysical reaction rate