Structure of low-lying states of 56,58Fe nuclei by α-particle inelastic scattering

Abstract

Differential cross sections for elastic and inelastic scattering of α-particles to various levels in 56,58Fe have been measured at incident α-particle energy of 25 MeV and have been analyzed in the framework of the coupled-channels formalism in terms of two collective models: the harmonic vibrational model and the asymmetric rotor model. The vibrational model describes well the data of the levels analyzed, but it was necessary to include a one-phonon component in the wave function of these states in order to reproduce the 2 2 + state angular distributions. The asymmetric rotor model predictions reproduce satisfactorily the 0 1 + − 2 1 + −2 2 +−4 1 + state angular distributions but the 4 2 +, 6 1 + and 6 2 + state data were underestimated by the model. Fits to these states were improved by including a β 4 deformation term in the potential. Evidence of an underestimation of the 4 + 2 → 2 + 1 and 6 + 2 → 4 + 2 elements by the model has been shown, that is corrected by the introduction of a hexadecapole term in the potential.