Unexpected transparency in low energy90Zr(α,α0)scattering andα-cluster structure in94Mo

Abstract

We show that incomplete absorption in 90Zr(α,α0) scattering is responsible for the spectacular dip observed in the backward excitation function at low energy (Eα≃ 25 MeV), which we interpret as a destructive interference effect between the barrier and internal wave contributions to the scattering amplitude. Because of this transparency, an optical potential, which is in line with the higher energy data, can be extracted with good accuracy. The real part of this potential is found to support several rotational bands; the properties of the states of the first Pauli-allowed band, with N = 16, in particular the electromagnetic transition rates between the first states, are in good agreement with those of the states of the experimental 94Mo ground state band, suggesting that α-cluster structure is still an important feature in the A = 90 region.