The 60Ni(p, γ) 61Cu AND 62Ni(p, γ) 63 Cu cross sections

Abstract

The cross sections of 60Ni(p, γ) 61Cu and 60Ni(p, p'γ) 60Ni have been measured over the bombarding-energy range 1.0–4.0 MeV, and of 62Ni(p, γ) 63Cu and 62Ni(p, p'γ) 62Ni over the bombarding-energy range 1.02–4.42 MeV. The measurements were based on observation of the yields of 61,63Cu and 60,62Ni de-excitation γ-rays. The cross sections, and those for proton induced reactions on all other stable nickel isotopes, have been compared with the predictions of statistical- model calculations. A new prescription for the optical-model proton imaginary well depth, for use with nickel isotopes only, is presented, leading to agreement between theory and experiment at the factor of 1.5 level. Thermonuclear reaction rates at temperatures representative of those encountered in freeze-out from nuclear statistical equilibrium in supernovae have been calculated from the data and the significance of these for stellar nucleosynthesis calculations is discussed. The excitation energies and (p, γ) resonance strengths of fifty-four resonances in 60Ni(p, γ) 61Cu, which feature significant resonance to ground-state transitions, have been measured.