The thermonuclear reaction rate of 58Si(p,γ) 59Cu

Abstract

The cross sections of 58Ni(p, γ) 59Cu and 58Ni(p, p'γ) 58Ni have been measured over the bombarding energy range 1.18–4.20 MeV. The measurements were based on observation of the yields of 59Cu and 58Ni deexcitation γ-rays and also on observation of the yield of γ-rays associated with the β + decay of 59Cu. The agreement between the two methods used for 58Ni(p, γ) 59Cu is very good. The cross sections have been compared with the predictions of global statistical-model calculations. The calculations overestimated the 58Ni(p, γ) 59Cu cross section by a factor ∼ 2.5 and the 58Ni(p, p'γ) 58Ni cross section by a factor ∼ 1.5. The energies and (p, γ 0) resonance strengths of sixty-five resonances which feature significant resonance to ground-state transitions were measured. These energies and resonance strengths are compared with other results in the literature and good overall agreement is found. Thermonuclear reaction rates at temperatures representative of those encountered in freeze-out from nuclear statistical equilibrium in exploding stars have been calculated from the data and the results compared with those of four previous measurements reported in the literature, amongst which there is significant disagreement. The present results are in satisfactory agreement with those of the two previous measurements based on stopping-target activation measurements. The significance of the reaction rates for stellar nucleosynthesis calculations is discussed.