The 56Fe(α, γ) 60Ni reaction at excitation energies in the region of the giant dipole resonance

Abstract

Excitation functions for the 56Fe( α, γ 0) 60Ni and 56Fe( α, γ 1) 60Ni reactions have been measured at 90° to the beam direction over the bombarding energy range 8.0–17.6 MeV. Gamma-ray angular distributions were measured at ten bombarding energies. Excitation functions for the 59Co(p, γ 0) 60Ni and 59Co(p, γ 1) 60Ni reactions were measured over the range E x = 16.58–16.92 MeV and compared with the (α, γ) data. The angular distribution data indicate that the ( α, γ 0) and ( α, γ 1) reactions proceed through 1 −, and 1 − and 3 − states, respectively. The (α, γ) excitation functions are discussed with respect to isospin splitting of the 60Ni giant dipole resonance. The fine structure observed in the excitation functions is shown to be most probably due to Ericson fluctuations. The gross (α, γ) cross sections are shown to be in reasonable agreement with the results of calculations made using the theory of Hauser and Feshbach assuming excitation of the giant dipole resonance.