α-decay of giant electric quadrupole resonances

Absolute probabilities of the direct α decay of giant quadrupole resonances (GQR) in 16O and 40Ca nuclei have been calculated on the basis of integral formulae for the α widths and using the shell model spectroscopic factors for α particles. An importance of an accounting for an interference of diagonal and non-diagonal α-decay mechanisms is shown for 16O. It is shown that an additional account for the statistical mechanism enables to describe the experimental probabilities of the α decay of GQR. It is concluded that the contributions from the direct and statistical mechanisms are comparable in all the cases investigated. Calculated partial yields of different α-decay modes of GQR and the integral spectra of α particles agree with the experimental data. Estimates are presented for the direct α-decay probabilities of the E2 resonances in nuclei 58-62Ni